This is a commentary on how C.H. Waddington's experiments in the 1950's, first published in 1953 in a provocatively titled paper "Genetic assimilation of an acquired character," laid the foundation for the field of phenotypic plasticity, and how the ideas he developed eventually led to new ways of understanding phenotypic robustness, plasticity, and how novel traits develop and evolve. The "acquired characters" that Waddington worked with were based on Goldschmidt's ideas of "phenocopies": new phenotypes that develop after an environmental stress that resemble the phenotypes of known mutations. The idea behind genetic assimilation, first outlined by Waddington in 1942, is that existing developmental pathways can be rearranged and redirected through selection to stabilize the phenocopy phenotype, without requiring new mutations. In the short term, Waddington's work led to the discovery of heat shock proteins and the role of Hsp90 in masking defective proteins and allowing the accumulation of cryptic genetic variation. Subsequent studies revealed a host of stabilizing systems that operate at all levels of biological organization that make phenotypes robust to genetic and environmental variation. Many of these resemble homeostatic mechanisms that don't require a stress shock but operate under normal physiological conditions and allow for the accumulation of large amounts of cryptic genetic variation. This cryptic genetic variation can be revealed by mutations or environmental factors that destabilize a homeostatic mechanism. Selection can then act on the phenotypic variants that are produced. This scenario corresponds to the modern phenotype-first hypothesis for the evolution of novel traits that was foreseen by Waddington as early as 1942.

Pre-eclampsia, placental abruption, and fetal growth restriction (FGR) are collectively referred to as placental ischemic disease (PID). Heat shock proteins (HSPs), originally considered as a response to the heat shock, have a central role in regulating the cellular functions by quality controlling the newly synthesized proteins. The aim of the present review is to investigate the expression of the HSPs in PID and their potential role as biomarkers, based on the available data in the literature. A considerable amount of research has been conducted in order to determine the significance of HSPs in placental pathology and insufficiency, using both immunochemistry and circulating mRNA approaches. HSPs seem to be promising biomarkers that could be used for screening and monitoring the cellular stress of the placenta and its dysfunction. Yet, in order to be able to reach more solid evidence and draw a safer conclusion regarding their utility in clinical practice there is still a long way to go and further well-designed greater scale studies are required.

This review summarizes the structure, function, expression, and inhibitors of HSP90, the chaperone, in cancers. It systematically investigates the effects of HSP90 inhibitors, including AUY922, B11B021, CCT-018159, D7-gedunin, geldanamycin, and gedunin, across a range of cancer cell lines (HCC151, HT29, MCF7, PC3, VCAP, and A375) and a normal HA1E cell line, using data from the CLUE database. Our analysis reveals that treatment with these HSP90 inhibitors induces significant stress responses in tumor cells, initiating intrinsic and extrinsic apoptotic pathways. The HSP90AA1, HSP90AB1, HSP27, HSP70, VEGF, and NOTCH exhibited notable upregulation at 24 h post-treatment compared to 6 h, indicating a time-dependent increase in cellular stress (heat shock response) and activation of pro-survival signaling mechanisms. Additionally, the study highlights a significant upregulation of immune-related pathways, including those involving IL10, IL3, and IL7, following HSP90 inhibition, indicating that these inhibitors not only directly affect tumor cell viability but also modulate the tumor microenvironment by enhancing immune cell activation and cytokine release. The elevated levels of IL10 point to a dual role, where immune suppression mechanisms are also at play, potentially facilitating immune evasion by the tumor. The findings suggest that HSP90 inhibitors exhibit varying mechanisms of action across different cancer cell lines despite the presence of some common targets. These insights highlight the need for further investigation into the precise mechanisms of HSP90 inhibitors to optimize their therapeutic potential in different cancers.

Cells respond to many different types of stresses by overhauling gene expression patterns, both at the transcriptional and translational levels. Under heat stress, global transcription and translation are inhibited, while the expression of chaperone proteins is preferentially favored. As the direct link between mRNA transcription and protein translation, transfer RNA (tRNA) expression is intricately regulated during the stress response. Despite extensive research into the heat shock response (HSR), the regulation of tRNA expression by RNA polymerase III (Pol III) transcription has yet to be fully elucidated in mammalian cells. Here, we examine the regulation of Pol III transcription during different stages of heat shock stress in mouse embryonic stem cells. We observe that Pol III transcription is downregulated after 30 min of heat shock, followed by an overall increase in transcription after 60 min of heat shock. This effect is more evident in tRNAs, although other Pol III gene targets are also similarly affected. Notably, we show that the downregulation at 30 min of heat shock is independent of HSF1, the master transcription factor of the HSR, but that the subsequent increase in expression at 60 min requires HSF1. Taken together, these results demonstrate an adaptive RNA Pol III response to heat stress and an intricate relationship between the canonical HSR and tRNA expression.

Under stress, cells orchestrate a complex regulatory response to maintain protein homeostasis, leveraging differential translational regulation for constitutively expressed mRNAs and the transcriptionally induced heat shock protein HSP70 transcripts. Constitutive mRNAs typically experience partial translational suppression, consistent with their partitioning into stress-induced phase-separated condensates and the global reduction in protein synthesis. In contrast, inducible HSP70 mRNAs bypass this repression to remain in the cytosol where they recruit the available components of the translational machinery to ensure the rapid synthesis of HSP70. Although the components involved in the preferential translation of HSP70 mRNA during heat stress have not been fully elucidated, differences in the mRNA and translation factors between yeast and mammals suggest organism-specific mechanisms of HSP70 mRNA translation. In this review, we consider these differences to discuss the current knowledge on heat shock regulation of translation. We extend the discussion to go beyond the cytosolic needs of HSP70 to ponder the important interplay between the cytosol and mitochondria in activating HSP70 accumulation, which becomes vital for preserving intercompartmental proteostasis and cell survival.

Heat shock proteins (HSPs) play a pivotal role in maintaining cellular homeostasis and mediating stress responses across diverse organisms. Among them, the HSP70 family is crucial for protein folding and stress regulation. However, its functions remain underexplored in mosquito species, particularly in major Indian malaria vectors such as Anopheles culicifacies (Ac). This study aims to contribute to mosquito control by investigating the role of HSP70 in An. culicifacies. Given the persistent global challenge posed by malaria, understanding the regulatory mechanisms of HSP70 is essential for developing effective control strategies. In this study, we identified seven HSP70 genes in An. culicifacies and analyzed their expression profiles across different life stages. Six of these HSP70 genes (1, 2, 3, 5, 6, and 7) exhibited significant upregulation during the third instar larval stage, emphasizing their critical role in larval development. Using specific HSP70 inhibitors, quercetin and KNK437, we observed that KNK437 displayed potent larvicidal activity, comparable to the widely used insecticide temephos. Additionally, we successfully purified and characterized recombinant AcHSP70-1, which demonstrated unique interactions with adenosine triphosphate (ATP) and its co-chaperone AcHSP40, distinguishing it from other HSP70 systems. Through a combination of confocal microscopy, qRT-PCR analysis, and inhibitor assays, we further established the essential role of HSP70 in both larval development and adult female mosquitoes during blood meal acquisition. These findings provide novel insights into the functional diversification and regulatory mechanisms of HSP70 genes in An. culicifacies. This study not only enhances our understanding of their developmental roles but also highlights innovative targets for the development of mosquito control strategies.

Heat shock proteins (HSPs) function as molecular chaperones to maintain protein homeostasis and repair denatured proteins, counteracting abiotic stresses. Despite their functional importance, a systematic bioinformatics analysis of the HSP gene family was lacking in Poaceae. In this study, we revealed that HSPs are widely distributed from algae to eudicots, with varying numbers in Poaceae including Oryza, Triticum, and Panicum. Gene duplication events, particularly dispersed duplication (DSD), tandem duplication (TD), and genome polyploidization, have probably driven the increased number of HSP genes and the expansion of HSP family proteins. Gene Ontology (GO) annotation analyses suggested their conserved functions. Promoter cis-acting element analyses indicated that their expression levels were tightly regulated by abiotic stresses. We validated that many collinear HSP genes are indeed regulated by the cold stress by analyzing the published RNA-seq data in rice, maize, and wheat, and performing RT-qPCR in rice. Our findings shed light on the role of HSPs in the abiotic stress response, laying the groundwork for further exploration of HSP functions in Poaceae.

The beta isoform of 90 kDa heat shock protein (Hsp90β) plays a critical role in maintaining cellular proteostasis by assisting in the folding and refolding of proteins, which is essential for both normal cellular function and stress response. It is constitutively expressed in mammalian cells, differentiating it from the inducible Hsp90α isoform. Hsp90β's involvement in diverse cellular processes, such as signal transduction, cell cycle control, and apoptosis, underscores its significant role in various diseases, including cancer and neurodegenerative disorders. The isoform-specific functions of Hsp90β and its interaction with unique client proteins make it a promising target for therapeutic intervention, particularly in the development of selective inhibitors that avoid the adverse effects observed with pan-Hsp90 inhibitors. This review delves into the structural and functional intricacies of Hsp90β, its role in disease, and the potential for selective drug development.

Therapy resistance is a major barrier to achieving a cure in cancer patients, often resulting in relapses and mortality. Heat shock proteins (HSPs) are a group of evolutionarily conserved proteins that play a prominent role in the progression of cancer and drug resistance. HSP synthesis is upregulated in cancer cells, facilitating adaptation to various tumor microenvironment (TME) stressors, including nutrient deprivation, exposure to DNA-damaging agents, hypoxia, and immune responses. In this review, we present background information about HSP-mediated cancer therapy resistance. Within this context, we emphasize recent progress in the understanding of HSP machinery, exploring the therapeutic potential of HSPs in cancer treatment.

Heat shock factor 1 (HSF1) is the master orchestrator of the heat shock response (HSR), a critical process for maintaining cellular health and protein homeostasis. These effects are achieved through rapid expression of molecular chaperones, the heat shock proteins (HSPs), which ensure correct protein folding, repair, degradation and stabilization of multiprotein complexes. In addition to its role in the HSR, HSF1 influences the cell cycle, including processes such as S phase progression and regulation of the p53 pathway, highlighting its importance in cellular protein synthesis and division. While HSF1 activity offers neuroprotective benefits in neurodegenerative diseases, its proteome-stabilizing function may also reinforce tumorigenic transformation. HSF1 overexpression in many types of cancer reportedly enhances cell growth enables survival, alters metabolism, weakens immune response and promotes angiogenesis or epithelial-mesenchymal transition (EMT) as these cells enter a form of "HSF1 addiction". Furthermore, the client proteins of HSF1-regulated chaperones, particularly Hsp90, include numerous key players in classical tumorigenic pathways. HSF1 thus presents a promising therapeutic target for cancer treatment, potentially in combination with HSP inhibitors to alleviate typical initiation of HSR upon their use.

Molecular chaperones, a class of complex client regulatory systems, play significant roles in the prevention of protein misfolding and abnormal aggregation, the modulation of protein homeostasis, and the protection of cells from damage under constantly changing environmental conditions. As the understanding of the biological mechanisms of molecular chaperones has increased, their link with the occurrence and progression of disease has suggested that these proteins are promising targets for therapeutic intervention, drawing intensive interest. Here, we review recent advances in determining the structures of molecular chaperones and heat shock protein 90 (HSP90) chaperone system complexes. We also describe the features of molecular chaperones and shed light on the complicated regulatory mechanism that operates through interactions with various co-chaperones in molecular chaperone cycles. In addition, how molecular chaperones affect diseases by regulating pathogenic proteins has been thoroughly analyzed. Furthermore, we focus on molecular chaperones to systematically discuss recent clinical advances and various drug design strategies in the preclinical stage. Recent studies have identified a variety of novel regulatory strategies targeting molecular chaperone systems with compounds that act through different mechanisms from those of traditional inhibitors. Therefore, as more novel design strategies are developed, targeting molecular chaperones will significantly contribute to the discovery of new potential drugs.

Plants are able to sense and remember heat stress. An initial priming heat stress enables plants to acclimate so that they are able to survive a subsequent higher temperature. The heat shock transcription factors (HSFs) play a crucial role in this process, but the mechanisms by which plants sense heat stress are not well understood. By comprehensively analyzing the binding targets of all the HSFs, we found that HSFs act in a network, with upstream sensory HSFs acting in a transcriptional cascade to activate downstream HSFs and protective proteins. The upstream sensory HSFs are activated by heat at the protein level via a modular prion-like domain (PrD) structure. PrD1 enables HSF sequestration via chaperone binding, allowing release under heat shock. Activated HSFs are recruited into transcriptionally active foci via PrD2, enabling the formation of DNA loops between heat-responsive promoters and enhancer motifs, boosting gene expression days after a priming heat stress. The ability of HSFs to respond rapidly to heat via a protein phase-change response is likely a conserved mechanism in eukaryotes.

There is increasing evidence indicating that global temperatures are rising significantly, a phenomenon commonly referred to as 'global warming', which in turn is believed to be causing drastic changes to the global climate. Global warming (GW) directly impacts animal health, reproduction, production, and welfare, presenting several challenges to livestock enterprises. Thermal stress (TS) is one of the key consequences of GW, and all animal species, including livestock, have diverse physiological, epigenetic and genetic mechanisms to respond to TS. As a result, TS can significantly affect an animals' health, immune responsiveness, metabolic pathways etc. which can also influence the productivity, performance, and welfare of animals. Moreover, prolonged exposure to TS can lead to transgenerational and intergenerational changes that are mediated by epigenetic changes. For example, in several animal species, the effects of TS are encoded epigenetically during the animals' growth or productive stage, and these epigenetic changes can be transmitted intergenerationally. Such epigenetic changes can affect animal productivity by changing the phenotype so that it aligns with its ancestors' environment, irrespective of its immediate environment. Furthermore, epigenetic and genetic changes can also help protect cells from the adverse effects of TS by modulating the transcriptional status of heat-responsive genes in animals. This review focuses on the genetic and epigenetic modulation and regulation that occurs in TS conditions via HSPs, histone alterations and DNA methylation.

Heat shock proteins are molecular chaperones that play crucial roles in the folding and unfolding of complex polypeptides within the cellular system. These molecules are involved in various processes, including vesicular transport, prevention of protein aggregation in the cytosol, and cell signaling. They are also linked to autoimmunity, infection immunity, and tumor immunology. Stressors like heat shock, exposure to heavy metals, cytokines, reactive oxygen species, inflammation, and viruses can influence the production of these molecules. In complex diseases such as cancer, malaria, and COVID-19, heat shock proteins are considered both biomarkers and drug targets. The upregulation of small heat shock proteins like hsp27 and major heat shock proteins 70/90 has been recognized as crucial biomarkers and therapeutic targets for cancer. Additionally, it has been reported that the invasion of Plasmodium falciparum, the causative agent of malaria, leads to the upregulation of heat shock proteins such as hsp40, hsp70, and hsp90. This sudden increase is a protective mechanism from the human host and enhances the parasite's growth, making these proteins significant as biomarkers and malarial drug targets. The presence of the SARS-CoV-2 virus in the human cellular system correlates with a substantial increase in heat shock protein 70 production from host cells. Furthermore, our research group has demonstrated that SARS-CoV-2 hijacks the host's heat shock proteins, and we are currently developing tools to prevent the virus from utilizing the host's protein folding system. This review aims to highlight the role of heat shock proteins as biomarkers and therapeutic targets for selected refractory diseases, focusing on cancer, malaria, and COVID-19. A fundamental molecular docking study was performed to investigate the interaction between a non-structural complex from SARS-CoV-2 and chosen small molecules, which is emphasized in this review.

Heat shock proteins (HSPs), particularly HSP90, play a vital role in insect responses to environmental and biotic stresses by maintaining protein stability and supporting immune defenses. This study explores HSP90 regulation in Galleria mellonella larvae following exposure to the nematode Steinernema carpocapsae and its symbiotic bacterium Xenorhabdus nematophila. Exposure to live nematodes caused slight changes in HSP90 expression, while non-viable nematodes had no effect, suggesting that nematode secretions or symbiotic bacteria do not directly influence HSP90 levels. However, nematodes with altered surface properties significantly increased HSP90 expression. X. nematophila also moderately elevated HSP90 levels but this effect disappeared when weakly bound surface proteins were removed. Interestingly, under thermal stress, live nematodes reduced heat-induced HSP90 expression, whereas surface-treated nematodes enhanced it. These findings suggest that HSP90 modulation is influenced by biological control agents, highlighting a potential link between HSP90 and immune detection of invaders. This interaction may be crucial in adapting biological control strategies in response to climate change. Further research is needed to clarify HSP activation pathways, host immune interactions, and mechanisms of entomopathogen immune evasion, particularly under varying environmental temperatures, to enhance bioinsecticide efficacy.

Aphis gossypii is a highly polyphagous pest that causes substantial agricultural damage. Temperature and insecticides are two major abiotic stresses affecting their population abundance. Heat shock proteins play an essential role in cell protection when insects are exposed to environmental stresses. Three ApHsp70 genes were cloned from A. gossypii, and characterized their molecular features and expression profiles in response to temperature and insecticide stress. The deduced amino acid sequences of these proteins exhibited characteristic Hsp70 family signatures, and their tissue-specific expression patterns revealed their highest activity to be in the salivary glands under 35 °C. The temperature inductive assay further indicated that the expression of the three ApHsp70 genes was markedly upregulated under heat stress but not under cold shock. Furthermore, exposure to LC25 and LC50 concentrations of three insecticides triggered the upregulation of these ApHsp70 genes. The RNA interference (RNAi)-mediated suppression of ApHsp68 expression heightened cotton aphid's susceptibility to insecticides (acetamiprid and sulfoxaflor). Moreover, our study found that the sulfoxaflor-resistant strain of A. gossypii (Sul-R) displayed a higher survival rate compared with the sulfoxaflor-sensitive strain (Sul-S) under heat shock conditions. These results suggest that these three ApHsp70 genes play an essential role in response to both heat and insecticide stress.

Microbes play an essential role in soil fertility by replenishing the nutrients; they encounter various biotic and abiotic stresses disrupting their cellular homeostasis, which expedites activating a conserved signaling pathway for transient over-expression of heat shock proteins (HSPs). In the present study, a versatile soil bacterium Bacillus subtilis strain PSK.A2 was isolated and characterized. Further, the isolated bacterium was exposed with several stresses, viz., heat, salt, acid, alkaline, and antibiotics. Stress-attributed cellular morphological modifications such as swelling, shrinkage, and clump formation were observed under the scanning electron microscope. The comparative protein expression pattern was studied by SDS-PAGE, relative protein stabilization was assessed by protein aggregation assay, and relative survival was mapped by single spot dilution and colony-counting method under control, stressed, lethal, and stressed lethal conditions of the isolate. The findings demonstrated that bacterial stress tolerance was maintained via the activation of various HSPs of molecular weight ranging from 17 to 115 kD to respective stimuli. The treatment of subinhibitory dose of antibiotics not interfering protein synthesis (amoxicillin and ciprofloxacin) resulted in the expression of eight HSPs of molecular weight ranging from 18 to 71 kD. The pre-treatment of short stress dosage showed endured overall tolerance of bacterium to lethal conditions, as evidenced by moderately enhanced total soluble intracellular protein content, better protein stabilization, comparatively over-expressed HSPs, and relatively enhanced cell survival. These findings hold an opportunity for developing novel approaches towards enhancing microbial resilience in a variety of conditions, including industrial bioprocessing, environmental remediation, and infectious disease management.

Lettuce is a crop particularly vulnerable to drought. A transcriptomic study in the variety 'Romired' and the wild relative Lactuca homblei was conducted to understand the increase in anthocyanins (only significant in L. homblei) in response to drought previously observed. RNA-seq revealed more differentially expressed genes (DEGs), especially upregulated, in the wild species, in which the most abundant and significant GO terms were involved in regulatory processes (including response to water). Anthocyanin synthesis was triggered in L. homblei in response to drought, with 17 genes activated out of the 36 mapped in the phenylpropanoid-flavonoid pathway compared to 7 in 'Romired'. Nineteen candidate DEGs with the strongest change in expression and correlation with both anthocyanin content and drought were selected and validated by qPCR, all being differentially expressed only in the wild species with the two techniques. Their functions were related to anthocyanins and/or stress response and they harboured 404 and 11 polymorphisms in the wild and cultivated species, respectively. Some wild variants had high or moderate predicted impacts on the respective protein function: a transcription factor that responds to abiotic stresses, a heat shock protein involved in stomatal closure, and a phospholipase participating in anthocyanin accumulation under abiotic stress. These genetic variants could explain the differences in the gene expression patterns between the wild (significantly up/downregulated) and the cultivated (no significant changes) species. The diversity of this crop wild relative for anthocyanin-related genes involved in the response to drought could be exploited to improve lettuce resilience against some adverse climate effects.

Pathogenic bacteria can detect a variety of environmental signals, including temperature changes. While sudden and significant temperature variations act as danger signals that trigger a protective heat-shock response, minor temperature fluctuations typically signal to the pathogen that it has moved from one environment to another, such as entering a specific niche within a host during infection. These latter temperature fluctuations are utilized by pathogens to coordinate the expression of crucial virulence factors. Here, we elucidate the critical role of temperature in governing the expression of virulence factors in bacterial pathogens. Moreover, we outline the molecular mechanisms used by pathogens to detect temperature fluctuations, focusing on systems that employ proteins and nucleic acids as sensory devices. We also discuss the potential implications and the extent of the risk that climate change poses to human pathogenic diseases.

Major depressive disorder (MDD) is characterized by high rates of disability and death and has become a public health problem that threatens human life and health worldwide. HPA axis disorder and neuroinflammation are two common biological abnormalities in MDD patients. Hsp90 is an important molecular chaperone that is widely distributed in the organism. Hsp90 binds to the co-chaperone and goes through a molecular chaperone cycle to complete its regulation of the client protein. Numerous studies have demonstrated that Hsp90 regulates how the HPA axis reacts to stress and how GR, the HPA axis' responsive substrate, matures. In addition, Hsp90 exhibits pro-inflammatory effects that are closely related to neuroinflammation in MDD. Currently, Hsp90 inhibitors have made some progress in the treatment of a variety of human diseases, but they still need to be improved. Further insight into the role of Hsp90 in MDD provides new ideas for the development of new antidepressant drugs targeting Hsp90.

Understanding physiological mechanisms of tolerance to heat exposure, and potential ways to improve such tolerance, is increasingly important in the context of ongoing climate change. We discuss the concept of heat tolerance in humans and experimental models (primarily rodents), including intracellular mechanisms and improvements in tolerance with heat acclimation.

Molecular chaperones are vital proteins that maintain protein homeostasis by assisting in protein folding, activation, degradation, and stress protection. Among them, heat-shock protein 90 (Hsp90) stands out as an essential proteostasis hub in eukaryotes, chaperoning hundreds of 'clients' (substrates). After decades of research, several 'known unknowns' about the molecular function of Hsp90 remain unanswered, hampering rational drug design for the treatment of cancers, neurodegenerative, and other diseases. We highlight three fundamental open questions, reviewing the current state of the field for each, and discuss new opportunities, including single-molecule technologies, to answer the known unknowns of the Hsp90 chaperone.

Heat shock proteins 70 KDa (Hsp70s) engage in a broad spectrum of cellular functions in response to various stressors. Marine bivalves face substantial threats from the rising seawater temperature attributed to global warming. In the present study, expression patterns of Hsp70s in Zhikong scallop Chlamys farreri (CfHsp70s) were determined in embryos and larvae at all developmental stages, in healthy adult tissues, and across four various tissues exposed to high temperature for acute and chronic periods through in silico analysis. Spatiotemporal expressions suggested CfHsp70s performed specific functional differentiations in scallop's development and growth. Regulatory expression patterns of CfHsp70s, characterized by predominant down-regulation in the mantle, gill and hemocytes, as well as contrasting up-regulation in the heart, suggest differential functional allocation of CfHsp70s among tissues in response to heat stress. Particularly, a core set of 14 CfHsp70s, especially the nine members of the Hsp70B2s, characterized by gene expansion, intron-less structure, shorter gene length, preference for hydrophilic amino acids, and coordinated expression profiles, was predominantly responsible for the inducible up-regulations observed across all four tissue types. Collectively, the tissue-specific, temporal and core gene-dependent expression patterns of CfHsp70s illustrate the functional allocation and molecular evolution of Hsp70 family members in Zhikong scallops.

Heat shock protein 20 (HSP20) is a diverse and functionally important protein family that plays a crucial role in plants' tolerance to various abiotic stresses. In this study, we systematically analyzed the structural and functional characteristics of the HSP20 gene family within the Zea pan-genome. By identifying 56 HSP20 pan-genes, we revealed the variation in the number of these genes across different maize inbreds or relatives. Among those 56 genes, only 31 are present in more than 52 inbreds or relatives. Further phylogenetic analysis classified these genes into four major groups (Class A, B, C, D) and explored their diversity in subcellular localization, physicochemical properties, and the terminal structures of those HSP20s. Through collinearity analysis and Ka/Ks ratio calculations, we found that most HSP20 genes underwent purifying selection during maize domestication, although a few genes showed signs of positive selection pressure. Additionally, expression analysis showed that several HSP20 genes were significantly upregulated under high temperatures, particularly in tassels and leaves. Co-expression network analysis revealed that HSP20 genes were significantly enriched in GO terms related to environmental stress responses, suggesting that HSP20 genes not only play key roles in heat stress but may also be involved in regulating various other biological processes, such as secondary metabolism and developmental processes. These findings expand our understanding of the functions of the maize HSP20 family and provide new insights for further research into maize's response mechanisms to environmental stresses.

Heat shock proteins are essential molecular chaperones that play crucial roles in stabilizing protein structures, facilitating the repair or degradation of damaged proteins, and maintaining proteostasis and cellular functions. Extensive research has demonstrated that heat shock proteins are highly expressed in cancers and closely associated with tumorigenesis and progression. The "Hallmarks of Cancer" are the core features of cancer biology that collectively define a series of functional characteristics acquired by cells as they transition from a normal state to a state of tumor growth, including sustained proliferative signaling, evasion of growth suppressors, resistance to cell death, enabled replicative immortality, the induction of angiogenesis, and the activation of invasion and metastasis. The pivotal roles of heat shock proteins in modulating the hallmarks of cancer through the activation or inhibition of various signaling pathways has been well documented. Therefore, this review provides an overview of the roles of heat shock proteins in vital biological processes from the perspective of the hallmarks of cancer and summarizes the small-molecule inhibitors that target heat shock proteins to regulate various cancer hallmarks. Moreover, we further discuss combination therapy strategies involving heat shock proteins and promising dual-target inhibitors to highlight the potential of targeting heat shock proteins for cancer treatment. In summary, this review highlights how targeting heat shock proteins could regulate the hallmarks of cancer, which will provide valuable information to better elucidate and understand the roles of heat shock proteins in oncology and the mechanisms of cancer occurrence and development and aid in the development of more efficacious and less toxic novel anticancer agents.

As the first member of the solute carrier 6 (SLC6) protein family, the γ-aminobutyric acid (GABA) transporter 1 (GAT1, SLC6A1), plays a pivotal role in the uptake of GABA from the synaptic cleft into neurons and astrocytes. This process facilitates the subsequent storage of GABA in presynaptic vesicles. The human SLC6A1 gene is highly susceptible to missense mutations, leading to severe clinical outcomes, such as epilepsy, in the afflicted patients. The molecular mechanisms of SLC6A1-associated disorders are discerned to some degree; many SLC6A1 mutations are now known to impair protein folding, and consequently fail to reach the plasma membrane. Inherently, once inside the endoplasmic reticulum (ER), GAT1 abides by a complex cascade of events that enable efficient intracellular trafficking. This involves association with specialized molecular chaperones responsible for steering the protein folding process, oligomerization, sorting through the Golgi apparatus, and ultimately delivery to the cell surface. The entire process is subject to stringent quality control mechanisms at multiple checkpoints. While the majority of the existing loss-of-function SLC6A1 variants interfere with folding and membrane targeting, certain mutants retain abundant surface expression. In either scenario, suppressed GAT1 activity disrupts GABAergic neurotransmission, preceding the disease manifestation in individuals harboring these mutations. The nervous system is enthralling and calls for systematic, groundbreaking research efforts to dissect the precise molecular factors associated with the onset of complex neurological disorders, and uncover additional non-canonical therapeutic targets. Recent research has given hope for some of the misfolded SLC6A1 variants, which can be salvaged by small molecules, i.e., chemical and pharmacological chaperones, acting on multiple upstream targets in the secretory pathway. We here highlight the significance of pharmacochaperoning as a therapeutic strategy for the treatment of SLC6A1-related disorders.

In organisms with complex life cycles, life stages that are most susceptible to environmental stress may determine species persistence in the face of climate change. Early embryos of Drosophila melanogaster are particularly sensitive to acute heat stress, yet tropical embryos have higher heat tolerance than temperate embryos, suggesting adaptive variation in embryonic heat tolerance. We compared transcriptomic responses to heat stress among tropical and temperate embryos to elucidate the gene regulatory basis of divergence in embryonic heat tolerance. The transcriptomes of tropical and temperate embryos differed in both constitutive and heat-stress-induced responses of the expression of relatively few genes, including genes involved in oxidative stress. Most of the transcriptomic response to heat stress was shared among all embryos. Embryos shifted the expression of thousands of genes, including increases in the expression of heat shock genes, suggesting robust zygotic gene activation and demonstrating that, contrary to previous reports, early embryos are not transcriptionally silent. The involvement of oxidative stress genes corroborates recent reports on the critical role of redox homeostasis in coordinating developmental transitions. By characterizing adaptive variation in the transcriptomic basis of embryonic heat tolerance, this study is a novel contribution to the literature on developmental physiology and developmental genetics.

The heat shock response (HSR) is a gene regulatory program controlling expression of molecular chaperones implicated in aging, cancer, and neurodegenerative disease. Long presumed to be activated by toxic protein aggregates, recent work suggests a new functional paradigm for the HSR in yeast. Rather than toxic aggregates, adaptive biomolecular condensates comprised of orphan ribosomal proteins (oRP) and stress granule components have been shown to be physiological chaperone clients. By titrating away the chaperones Sis1 and Hsp70 from the transcription factor Hsf1, these condensates activate the HSR. Upon release from Hsp70, Hsf1 forms spatially distinct transcriptional condensates that drive high expression of HSR genes. In this manner, the negative feedback loop controlling HSR activity - in which Hsf1 induces Hsp70 expression and Hsp70 represses Hsf1 activity - is embedded in the biophysics of the system. By analogy to phosphorylation cascades that transmit information via the dynamic activity of kinases, we propose that the HSR is organized as a condensate cascade that transmits information via the localized activity of molecular chaperones.

Heat shock protein 20 (Hsp20) plays a very important role in response to abiotic stressors such as drought; however, in lettuce (Lactuca sativa L.), this gene family is poorly understood. This study used bioinformatics methods to identify 36 members of the lettuce Hsp20 family, which were named LsHsp20-1~LsHsp20-36. Subcellular localization results revealed that 26 members of the LsHsp20 protein family localized to the cytoplasm and nucleus. Additionally, 15 conserved domains were identified in the LsHsp20 protein family, with the number of amino acids ranging from 8 to 50. Gene structure analysis revealed that 15 genes (41.7%) had no introns, and 20 genes (55.5%) had one intron. The proportion of the LsHsp20 secondary structure was random coil > alpha helix > extended strand > beta turn. Chromosome positioning analysis indicated that 36 genes were unevenly distributed on nine chromosomes, and four pairs of genes were collinear. The Ka/Ks ratio of the collinear genes was less than 1, indicating that purifying selection dominated during L. sativa evolution. Thirteen pairs of genes were collinear in lettuce and Arabidopsis, and 14 pairs of genes were collinear in lettuce and tomato. A total of 36 LsHsp20 proteins were divided into 12 subgroups based on phylogenetic analysis. Three types of cis-acting elements, namely, abiotic and biotic stress-responsive, plant hormone-responsive, and plant development-related elements, were identified in the lettuce LsHsp20 family. qRT-PCR was used to analyze the expression levels of 23 LsHsp20 genes that were significantly upregulated on the 7th or 14th day of drought treatment, and the expression levels of two genes (LsHsp20-12 and LsHsp20-26) were significantly increased by 153-fold and 273-fold on the 14th and 7th days of drought treatment, respectively. The results of this study provide comprehensive information for research on the LsHsp20 gene family in lettuce and lay a solid foundation for further elucidation of Hsp20 biological functions, providing valuable information on the regulatory mechanisms of the LsHsp20 family in lettuce drought resistance.

Climate change is an increasing concern of stakeholders worldwide. The intestine is severely impacted by the heat stress. This study aimed to investigate the alleviating effects of methionine on the intestinal damage induced by heat stress in mice. The mice were divided into four groups: control group (C), methionine deficiency group (MD), methionine + heat stress group (MH), and methionine deficiency + heat stress group (MDH). Histopathological techniques, PAS-Alcian blue staining, immunohistochemistry method, biochemical quantification method, ELISA, and micro method were used to study the changes in the intestinal mucosal morphology, the number of goblet cells, the expression of tight junction proteins, the peroxide product contents and antioxidant enzyme activities, the intestinal mucosal damage, the content of immunoglobulins and HSP70, the activity of Na+/K+-ATPase. The results showed that methionine can improve intestinal mucosal morphology (increase the villi height, V/C value, and muscle layer thickness, decrease crypt depth), increase the expression of tight junction proteins (Claudin-1, Occludin, ZO-1) and the content of DAO, decrease the content of intestinal mucosa damage markers (ET, FABP2) and peroxidation products (MDA), increase the activity of antioxidant enzymes (GR, GSH-Px, SOD), the number of goblet cells, the contents of immunoglobulins (sIgA, IgA, IgG, IgM) and stress protein (HSP70), and the activity of Na+/K+-ATPase. It is suggested that methionine can alleviate intestinal damage in heat-stressed mice.

More than 99% of the mitochondrial proteome is encoded by the nucleus and requires refolding following import. Therefore, mitochondrial proteins require the coordinated action of molecular chaperones for their folding and activation. Several heat shock protein (Hsp) molecular chaperones, including members of the Hsp27, Hsp40/70, and Hsp90 families, as well as the chaperonin complex Hsp60/10 have an established role in mitochondrial protein import and folding. The "Chaperone Code" describes the regulation of chaperone activity by dynamic post-translational modifications; however, little is known about the post-translational regulation of mitochondrial chaperones. Dissecting the regulation of chaperone function is essential for understanding their differential regulation in pathogenic conditions and the potential development of efficacious therapeutic strategies. Here, we summarize the recent literature on post-translational regulation of mitochondrial chaperones, the consequences for mitochondrial function, and potential implications for disease.

Autophagy mediates the degradation of intracellular macromolecules and organelles within lysosomes. There are three types of autophagy: macroautophagy, microautophagy, and chaperone-mediated autophagy. Heat shock protein 70.1 (Hsp70.1) exhibits dual functions as a chaperone protein and a lysosomal membrane stabilizer. Since chaperone-mediated autophagy participates in the recycling of ∼30% cytosolic proteins, its disorder causes cell susceptibility to stress conditions. Cargo proteins destined for degradation such as amyloid precursor protein and tau protein are trafficked by Hsp70.1 from the cytosol into lysosomes. Hsp70.1 is composed of an N-terminal nucleotide-binding domain (NBD) and a C-terminal domain that binds to cargo proteins, termed the substrate-binding domain (SBD). The NBD and SBD are connected by the interdomain linker LL1, which modulates the allosteric structure of Hsp70.1 in response to ADP/ATP binding. After the passage of the Hsp70.1-cargo complex through the lysosomal limiting membrane, high-affinity binding of the positive-charged SBD with negative-charged bis(monoacylglycero)phosphate (BMP) at the internal vesicular membranes activates acid sphingomyelinase to generate ceramide for stabilizing lysosomal membranes. As the integrity of the lysosomal limiting membrane is critical to ensure cargo protein degradation within the acidic lumen, the disintegration of the lysosomal limiting membrane is lethal to cells. After the intake of high-fat diets, however, β-oxidation of fatty acids in the mitochondria generates reactive oxygen species, which enhance the oxidation of membrane linoleic acids to produce 4-hydroxy-2-nonenal (4-HNE). In addition, 4-HNE is produced during the heating of linoleic acid-rich vegetable oils and incorporated into the body via deep-fried foods. This endogenous and exogenous 4-HNE synergically causes an increase in its serum and organ levels to induce carbonylation of Hsp70.1 at Arg469, which facilitates its conformational change and access of activated μ-calpain to LL1. Therefore, the cleavage of Hsp70.1 occurs prior to its influx into the lysosomal lumen, which leads to lysosomal membrane permeabilization/rupture. The resultant leakage of cathepsins is responsible for lysosomal cell death, which would be one of the causative factors of lifestyle-related diseases.

Since domestication, both evolutionary forces and human selection have played crucial roles in producing adaptive and economic traits, resulting in animal breeds that have been selected for specific climates and different breeding goals. Pakistani goat breeds have acquired genomic adaptations to their native climate conditions, such as tropical and hot climates. In this study, using next-generation sequencing data, we aimed to assess the signatures of positive selection in three native Pakistani goats, known as milk production breeds, that have been well adapted to their local climate.

To explore the genomic relationship between studied goat populations and their population structure, whole genome sequence data from native goat populations in Pakistan (n = 26) was merged with available worldwide goat genomic data (n = 184), resulting in a total dataset of 210 individuals. The results showed a high genetic correlation between Pakistani goats and samples from North-East Asia. Across all populations analyzed, a higher linkage disequilibrium (LD) level (- 0.59) was found in the Pakistani goat group at a genomic distance of 1 Kb. Our findings from admixture analysis (K = 5 and K = 6) showed no evidence of shared genomic ancestry between Pakistani goats and other goat populations from Asia. The results from genomic selection analysis revealed several candidate genes related to adaptation to tropical/hot climates (such as; KITLG, HSPB9, HSP70, HSPA12B, and HSPA12B) and milk production related-traits (such as IGFBP3, LPL, LEPR, TSHR, and ACACA) in Pakistani native goat breeds.

The results from this study shed light on the structural variation in the DNA of the three native Pakistani goat breeds. Several candidate genes were discovered for adaptation to tropical/hot climates, immune responses, and milk production traits. The identified genes could be exploited in goat breeding programs to select efficient breeds for tropical/hot climate regions.

Light and temperature sensing are important features of many organisms. Light may provide energy but may also be used by non-photosynthetic organisms for orientation in the environment. Recent evidence suggests that plant and fungal phytochrome and plant phototropin serve dual functions as light and temperature sensors. Here we characterized the fungal LOV-domain blue-light receptor LreA of Alternaria alternata and show that it predominantly contains FAD as chromophore. Blue-light illumination induced ROS production followed by protein agglomeration in vitro. In vivo ROS may control LreA activity. LreA acts as a blue-light photoreceptor but also triggers temperature-shift-induced gene expression. Both responses required the conserved amino acid cysteine 421. We therefore propose that temperature mimics the photoresponse, which could be the ancient function of the chromoprotein. Temperature-dependent gene expression control with LreA was distinct from the response with phytochrome suggesting fine-tuned, photoreceptor-specific gene regulation.

Proteostasis is essential for normal function of proteins and vital for cellular health and survival. Proteostasis encompasses all stages in the "life" of a protein, that is, from translation to functional performance and, ultimately, to degradation. Proteins need native conformations for function and in the presence of multiple types of stress, their misfolding and aggregation can occur. A coordinated network of proteins is at the core of proteostasis in cells. Among these, chaperones are required for maintaining the integrity of protein conformations by preventing misfolding and aggregation and guide those with abnormal conformation to degradation. The ubiquitin-proteasome system (UPS) and autophagy are major cellular pathways for degrading proteins. Although failure or decreased functioning of components of this network can lead to proteotoxicity and disease, like neuron degenerative diseases, underlying factors are not completely understood. Accumulating misfolded and aggregated proteins are considered major pathomechanisms of neurodegeneration. In this chapter, we have described the components of three major branches required for proteostasis-chaperones, UPS and autophagy, the mechanistic basis of their function, and their potential for protection against various neurodegenerative conditions, like Alzheimer's, Parkinson's, and Huntington's disease. The modulation of various proteostasis network proteins, like chaperones, E3 ubiquitin ligases, proteasome, and autophagy-associated proteins as therapeutic targets by small molecules as well as new and unconventional approaches, shows promise.

Cells must sense and respond to sudden maladaptive environmental changes-stresses-to survive and thrive. Across eukaryotes, stresses such as heat shock trigger conserved responses: growth arrest, a specific transcriptional response, and biomolecular condensation of protein and mRNA into structures known as stress granules under severe stress. The composition, formation mechanism, adaptive significance, and even evolutionary conservation of these condensed structures remain enigmatic. Here we provide a remarkable view into stress-triggered condensation, its evolutionary conservation and tuning, and its integration into other well-studied aspects of the stress response. Using three morphologically near-identical budding yeast species adapted to different thermal environments and diverged by up to 100 million years, we show that proteome-scale biomolecular condensation is tuned to species-specific thermal niches, closely tracking corresponding growth and transcriptional responses. In each species, poly(A)-binding protein-a core marker of stress granules-condenses in isolation at species-specific temperatures, with conserved molecular features and conformational changes modulating condensation. From the ecological to the molecular scale, our results reveal previously unappreciated levels of evolutionary selection in the eukaryotic stress response, while establishing a rich, tractable system for further inquiry.

The presence of HSPs in female reproductive and their relationship with the steroid hormone fluctuation have been reported in several mammals but not in non-human primates. The present research dealt with the oviductal expression and localization of the more studied HSPs (60, 70, and 90) as well as the morphological changes in the Hamadryas baboon (Papio hamadryas) during the follicular, preovulatory, and luteal phases of the menstrual cycle. Therefore, western blots, histomorphological, and immunohistochemical analyses were carried out. The results of western blot analysis displayed the lowest HSP expression in the luteal phase. The histomorphology showed that the mucosal epithelium consisted of undifferentiated cuboidal cells in follicular and luteal phases and well-distinguishable columnar ciliated and non-ciliated cells during the preovulatory phase. Immunohistochemistry evidenced that the mucosal epithelium contained cytoplasmic and nuclear HSP60, 70, and 90 immunostaining in the follicular and luteal phases. During the preovulatory phase, the non-ciliated cells showed: (i) cytoplasmic HSP60; (ii) nuclear and cytoplasmic HSP90. Ciliated cells showed cytoplasmic and ciliary HSP70 and ciliary HSP90. The stromal cells and myocytes of muscular layer displayed a decreased cytoplasmic HSP60 in the preovulatory phase and nuclear and low cytoplasmic HSP70 throughout the menstrual cycle. Nuclear HSP90 decreased in ampulla stromal cells and the follicular phase myocytes. These findings indicate that the expression pattern of HSP60,70, and 90 is related to the morphofunctional features of the baboon oviductal ampulla during the menstrual cycle and could represent a referent point for further studies in the oviduct of Primates.

Polyploid cells contain multiple genome copies and arise in many animal tissues as a regulated part of development. However, polyploid cells can also arise due to cell division failure, DNA damage or tissue damage. Although polyploidization is crucial for the integrity and function of many tissues, the cellular and tissue-wide consequences of polyploidy can be very diverse. Nonetheless, many polyploid cell types and tissues share a remarkable similarity in function, providing important information about the possible contribution of polyploidy to cell and tissue function. Here, we review studies on polyploid cells in development, underlining parallel functions between different polyploid cell types, as well as differences between developmentally-programmed and stress-induced polyploidy.

AbstractTropical ectotherms are thought to be especially vulnerable to climate change because they have evolved in temporally stable thermal environments and therefore have decreased tolerance for thermal variability. Thus, they are expected to have narrow thermal tolerance ranges, live close to their upper thermal tolerance limits, and have decreased thermal acclimation capacity. Although models often predict that tropical forest ectotherms are especially vulnerable to rapid environmental shifts, these models rarely include the potential for plasticity of relevant traits. We measured phenotypic plasticity of thermal tolerance and thermal preference as well as multitissue transcriptome plasticity in response to warmer temperatures in a species that previous work has suggested is highly vulnerable to climate warming, the Panamanian slender anole lizard (Anolis apletophallus). We found that many genes, including heat shock proteins, were differentially expressed across tissues in response to short-term warming. Under long-term warming, the voluntary thermal maxima of lizards also increased, although thermal preference exhibited only limited plasticity. Using these data, we modeled changes in the activity time of slender anoles through the end of the century under climate change and found that plasticity should delay declines in activity time by at least two decades. Our results suggest that slender anoles, and possibly other tropical ectotherms, can alter the expression of genes and phenotypes when responding to shifting environmental temperatures and that plasticity should be considered when predicting the future of organisms under a changing climate.

Exposure to both antibiotics and temperature changes can induce similar physiological responses in bacteria. Thus, changes in growth temperature may affect antibiotic resistance. Previous studies have found that evolution under antibiotic stress causes shifts in the optimal growth temperature of bacteria. However, little is known about how evolution under thermal stress affects antibiotic resistance. We examined 100+ heat-evolved strains of Escherichia coli that evolved under thermal stress. We asked whether evolution under thermal stress affects optimal growth temperature, if there are any correlations between evolving in high temperatures and antibiotic resistance, and if these strains' antibiotic efficacy changes depending on the local environment's temperature. We found that: (1) surprisingly, most of the heat-evolved strains displayed a decrease in optimal growth temperature and overall growth relative to the ancestor strain, (2) there were complex patterns of changes in antibiotic resistance when comparing the heat-evolved strains to the ancestor strain, and (3) there were few significant correlations among changes in antibiotic resistance, optimal growth temperature, and overall growth.

The heat shock response (HSR) is a crucial biochemical pathway that orchestrates the resolution of inflammation, primarily under proteotoxic stress conditions. This process hinges on the upregulation of heat shock proteins (HSPs) and other chaperones, notably the 70 kDa family of heat shock proteins, under the command of the heat shock transcription factor-1. However, in the context of chronic degenerative disorders characterized by persistent low-grade inflammation (such as insulin resistance, obesity, type 2 diabetes, nonalcoholic fatty liver disease, and cardiovascular diseases) a gradual suppression of the HSR does occur. This work delves into the mechanisms behind this phenomenon. It explores how the Western diet and sedentary lifestyle, culminating in the endoplasmic reticulum stress within adipose tissue cells, trigger a cascade of events. This cascade includes the unfolded protein response and activation of the NOD-like receptor pyrin domain-containing protein-3 inflammasome, leading to the emergence of the senescence-associated secretory phenotype and the propagation of inflammation throughout the body. Notably, the activation of the NOD-like receptor pyrin domain-containing protein-3 inflammasome not only fuels inflammation but also sabotages the HSR by degrading human antigen R, a crucial mRNA-binding protein responsible for maintaining heat shock transcription factor-1 mRNA expression and stability on heat shock gene promoters. This paper underscores the imperative need to comprehend how chronic inflammation stifles the HSR and the clinical significance of evaluating the HSR using cost-effective and accessible tools. Such understanding is pivotal in the development of innovative strategies aimed at the prevention and treatment of these chronic inflammatory ailments, which continue to take a heavy toll on global health and well-being.

Preserving and regulating cellular homeostasis in the light of changing environmental conditions or developmental processes is of pivotal importance for single cellular and multicellular organisms alike. To counteract an imbalance in cellular homeostasis transcriptional programs evolved, called the heat shock response, unfolded protein response, and integrated stress response, that act cell-autonomously in most cells but in multicellular organisms are subjected to cell-nonautonomous regulation. These transcriptional programs downregulate the expression of most genes but increase the expression of heat shock genes, including genes encoding molecular chaperones and proteases, proteins involved in the repair of stress-induced damage to macromolecules and cellular structures. Sixty-one years after the discovery of the heat shock response by Ferruccio Ritossa, many aspects of stress biology are still enigmatic. Recent progress in the understanding of stress responses and molecular chaperones was reported at the 12th International Symposium on Heat Shock Proteins in Biology, Medicine and the Environment in the Old Town Alexandria, VA, USA from 28th to 31st of October 2023.

Heat shock proteins (HSPs) are a class of protective proteins in response to abiotic stress in plants, and HSP20 plays an essential role in response to temperature stress. However, there are few studies on HSP20 in Dendrobium catenatum. In this study, 18 DcHSP20 genes were identified from the D. catenatum genome. Phylogenetic analysis showed that DcHSP20s could be classified into six subgroups, each member of which has similar conserved motifs and gene structures. Gene expression analysis of 18 DcHSP20 genes revealed that they exhibited variable expression patterns in different plant tissues. Meanwhile, all 18 DcHSP20 genes were induced to be up-regulated under high temperature, while six genes (DcHSP20-2/9/10/12/16/17) were significantly up-regulated under low temperature. Moreover, combining gene expression under high and low temperature stress, the DcHSP20-12 gene was cloned for functional analysis. The germination ratios, fresh weights, root lengths of two DcHSP20-12-overexpressing transgenic Arabidopsis thaliana lines were significantly higher, but MDA contents were lower than that of wild-type (WT) plants under heat and cold stresses, displayed enhanced thermotolerance and cold-resistance. These results lay a foundation for the functional characterization of DcHSP20s and provide a candidate gene, DcHSP20-12, for improving the tolerance of D. catenatum to temperature stress in the future.