The study of the structure and function of metalloproteins is a central subject of inorganic biochemistry. Starting from the 2000s, computational methods have flanked experimental research by exploiting the ever-increasing computing power and the huge amount of data produced by omics technologies. In this article, we retrace the major advancements that brought bioinformatics from being of minor relevance to being an essential tool for today's inorganic biochemists, focusing on the contributions coming from the Magnetic Resonance Center (CERM) of Florence, where we have been developing for twenty years methods and resources to investigate metalloproteins with computational approaches.

Zn2+ is essential for neuronal signaling, but imbalance cause cell death and neurodegenerative disorders. While the buffering system maintains low cytosolic Zn2+ concentration ([Zn2+]i), the details on physiological stimuli elevating [Zn2+]i for neuronal processes remain limited. Our previous reports have demonstrated that dopamine elevates [Zn2+]i through the cAMP-NO pathway, activating autophagy and inflammation in neurons. In this study, we adopted the Zn2+ imaging technique to verify how glutamate elevated [Zn2+]i in cultured cortical neurons and examined the inflammatory response. Our results showed that glutamate elevates the [Zn2+]i, by activating ionotropic glutamate receptors. Inhibitors of calmodulin (CaM), CaM-dependent protein kinase II (CaMKII), and NO synthase (NOS) blocked the glutamate-induced Zn2+ response. High-K+ buffer induced-membrane depolarization significantly elevated the intracellular Ca2+ concentration ([Ca2+]i) but only slightly increased [Zn2+]i and NO production. Glutamate also transiently increased NOS phosphorylation at Ser1417 within 15 min. The Zn2+ chelator, TPEN suppressed glutamate-induced inflammasome formation. These results indicate that glutamate-induced local increment in [Ca2+]i via the ionotropic glutamate receptors activates the CaM-CaMKII-NOS complex to produce NO and elevate [Zn2+]i. which trigger inflammation in cultured neurons. Henceforth, this novel glutamate-Zn2+ signaling pathway after glutamate depolarization elevates [Ca2+]i indicates the involvement of Zn2+ in modulating long-term neuronal activities.

In assisted reproduction, many factors in the culture environment, including light, temperature, pH, and culture media, can reduce preimplantation embryo viability. Laboratory glassware is also a known risk factor for in vitro embryos; however, the underlying mechanisms that disrupt embryonic development remain unclear. We identified Zn eluted from glassware as an embryotoxic substance. In mouse embryos, Zn induced delayed development, abnormalities in chromosome segregation, cytokinesis, zygotic gene activation (e.g. Zscan4a and murine endogenous retrovirus with leucine, also known as MERVL), and aberrantly upregulated developmental gene expression (e.g. Hoxa1, Hoxb9, T, and Fgf8) that could be mediated through metal regulatory transcription factors (e.g. Mtf1). Subsequently, Zn exposure led to significantly reduced blastocyst formation. Post-implantation, Zn-exposed embryos were associated with normal birth rates, however, the birth weight increased by an average of 18% compared with embryos cultured without Zn. Furthermore, Zn exposure affected the development of bovine and human embryos, with species-based variation in the strength and timing of these effects. To mitigate these embryotoxic effects, we identified a method to prevent glass toxicity using chelating agents. This research not only highlights the importance of risk control in embryo culture but also facilitates the development of safe and effective methods for assisted reproduction.

The imbalance in cellular ionic homeostasis represents a hallmark of several neurodegenerative diseases, including Amyotrophic Lateral Sclerosis (ALS). Zinc Transporter 1 (ZnT1), the first described member of the ZnT family, stands out as the sole member of the SLC30 family responsible for exporting cytosolic zinc to the extracellular space. While ZnT1 is expressed across all tissues and cell types studied, it exhibits the highest prominence within the central nervous system. In ALS SOD1G93A mice, a reduction in ZnT1 expression consistent with disease progression has been observed, prompting our investigation into its role in ALS pathophysiology. Remarkably, through the use of a sequence complementary to the microRNA let-7a (anti-Let-7a) able to modulate ZnT1 expression, we demonstrated in ALS mice its capability to: (1) prevent the reduction in ZnT1 levels in the spinal cord; (2) preserve motor neuron survival in the ventral spinal horn; (3) decrease astroglial and microglial activation while sparing resident microglial cells in the spinal cord; and (4) improve the lifespan and alleviate motor symptoms.

We designed a minimalistic zinc(II)-binding peptide featuring the Cys2His2 zinc-finger motif. To this aim, several tens of thousands of (His/Cys)-Xn-(His/Cys) protein fragments (n=2-20) were first extracted from the 3D protein structures deposited in Protein Data Bank (PDB). Based on geometrical constraints positioning two Cys (C) and two His (H) side chains at the vertices of a tetrahedron, approximately 22 000 sequences of the (H/C)-Xi-(H/C)-Xj-(H/C)-Xk-(H/C) type, satisfying Nmetal-binding H=Nmetal-binding C=2, were processed. Several other criteria, such as the secondary structure content and predicted fold stability, were then used to select the best candidates. To prove the viability of the computational design experimentally, three peptides were synthesized and subjected to isothermal calorimetry (ITC) measurements to determine the binding constants with Zn2+, including the entropy and enthalpy terms. For the strongest Zn2+ ions binding peptide, P1, the dissociation constant was shown to be in the nanomolar range (KD=~220 nM; corresponding to ΔGbind=-9.1 kcal mol-1). In addition, ITC showed that the [P1 : Zn2+] complex forms in 1 : 1 stoichiometry and two protons are released upon binding, which suggests that the zinc coordination involves both cysteines. NMR experiments also indicated that the structure of the [P1 : Zn2+] complex might be quite similar to the computationally predicted one. In summary, our proof-of-principle study highlights the usefulness of our computational protocol for designing novel metal-binding peptides.

Metal ions, as abundant and vital cofactors in numerous proteins, are crucial for enzymatic activities and protein interactions. Given their pivotal role and catalytic efficiency, accurately and efficiently identifying metal-binding sites is fundamental to elucidating their biological functions and has significant implications for protein engineering and drug discovery. To address this challenge, we present SuperMetal, a generative AI framework that leverages a score-based diffusion model coupled with a confidence model to predict metal-binding sites in proteins with high precision and efficiency. Using zinc ions as an example, SuperMetal outperforms existing state-of-the-art models, achieving a precision of 94 % and coverage of 90 %, with zinc ions localization within 0.52 ± 0.55 Å of experimentally determined positions, thus marking a substantial advance in metal-binding site prediction. Furthermore, SuperMetal demonstrates rapid prediction capabilities (under 10 seconds for proteins with ∼ 2000 residues) and remains minimally affected by increases in protein size. Notably, SuperMetal does not require prior knowledge of the number of metal ions-unlike AlphaFold 3, which depends on this information. Additionally, SuperMetal can be readily adapted to other metal ions or repurposed as a probe framework to identify other types of binding sites, such as protein-binding pockets.

The ubiquitous, evolutionarily oldest RNAs and proteins exclusively use rather rare zinc as transition metal cofactor and potassium as alkali metal cofactor, which implies their abundance in the habitats of the first organisms. Intriguingly, lunar rocks contain a hundred times less zinc and ten times less potassium than the Earth's crust; the Moon is also depleted in other moderately volatile elements (MVEs). Current theories of impact formation of the Moon attribute this depletion to the MVEs still being in a gaseous state when the hot post-impact disk contracted and separated from the nascent Moon. The MVEs then fell out onto juvenile Earth's protocrust; zinc, as the most volatile metal, precipitated last, just after potassium. According to our calculations, the top layer of the protocrust must have contained up to 1019 kg of metallic zinc, a powerful reductant. The venting of hot geothermal fluids through this MVE-fallout layer, rich in metallic zinc and radioactive potassium, both capable of reducing carbon dioxide and dinitrogen, must have yielded a plethora of organic molecules released with the geothermal vapor. In the pools of vapor condensate, the RNA-like molecules may have emerged through a pre-Darwinian selection for low-volatile, associative, mineral-affine, radiation-resistant, nitrogen-rich, and polymerizable molecules.

Neural tube defects (NTDs) are leading congenital malformations. Its global prevalence is one in 1000 pregnancies and it has high morbidity and mortality. It has multiple risk factors like genetic errors and environmental stressors like maternal malnutrition and in utero exposure to pollutants like chemicals. The genetic program determines neural tube development based on timely expression of many genes involved in developmental signaling pathways like BMP, PCP and SHH. BMP expression defines ectoderm. SOX represses BMP in ectoderm and convertes to the neuroectoderm. Subsequently, PCP molecules define the tissue patterning for convergent-extension, a critical step in neural tube genesis. Further, SHH sets spatial patterning of the neural tube. Nutrients are the essential major environmental input for embryogenesis. But it may also carry risk factors. Malnutrition, especially folate deficiency, during embryogenesis is a major cause for NTDs. Folate is integral in the One Carbon metabolic pathway. Its deficiency and error in the pathway are implicated in NTDs. Folate supplementation alone is insufficient to prevent NTDs. Thus, a comprehensive understanding of the various risk factors is necessary to strategize reduction of NTDs. We review the current knowledge of various risk factors, like genetic, metabolic, nutritional, and drugs causing NTDs and discuss the steps required to identify them in the early embryogenesis to avoid NTDs.

Early and accurate diagnosis of sepsis and the ensuing organ dysfunction remain a challenge in the postoperative setting. Susceptibility to infections, as well as the subsequent immunological response, are driven to some extent by the genetic predisposition of the patient. The purpose of this study was to identify novel genetic variants associated with postoperative sepsis (POS) and surgical site infections (SSIs).

We conducted genome-wide association studies for POS and SSIs in the Electronic Medical Records and Genomics Network database. All patients with surgical and genomic information in Electronic Medical Records and Genomics were identified. Patients with a new diagnosis of sepsis/SSIs after surgery were classified as cases, and those without as controls. Analyses were performed using PLINK 2.0's logistic regression function. A p value of <5 × 10 -8 was considered statistically significant.

A total of 59,755 participants were included in the analysis. Genetic regions on chromosomes 9 and 14 reached statistical significance for POS ( p < 5 × 10 -8 ). The most significant single-nucleotide polymorphisms (SNPs) were rs9413988 ( p = 5.59 × 10 -12 ) on chromosome 9 and rs35407594 ( p = 1.43 × 10 -10 ) on chromosome 14. The rs9413988 region is downstream to the phosphoglucomutase 5 pseudogene ( PGM5P2 ) and Zn-regulated GTPase metalloprotein activator 1F ( ZNGF1 ) and likely plays a role in transcription regulation, while rs35407594 corresponds to the olfactory receptor gene family, OR11 . Similar SNPs were also associated with SSIs.

We have identified two genetic regions containing SNPs associated with POS and SSIs. These findings provide new avenues for investigation, which may help identify and guide point-of-care management for at-risk patients.

Prognostic and Epidemiological; Level III.

This perspective discusses the essential micronutrient zinc, which functions in >3000 human proteins (the zinc proteome), and the implications of three aspects to ascertain an adequate zinc status for human health. First, the advent of highly sensitive fluorescent (bio)chemicals revealed cellular pools of zinc ions involved in signaling and secretion from cells for paracrine, autocrine, and possibly endocrine functions. Zinc signaling adds a yet unaccounted number of targeted proteins to the already impressive number of zinc proteins. Second, cellular zinc concentrations are remarkably high in the order of the concentrations of major metabolites and, therefore, at the cellular level zinc is not a trace element. Zinc is also not an antioxidant because zinc ions are redox-inactive in biology. However, zinc can express indirect pro-oxidant or proantioxidant effects depending on how cellular zinc is buffered. Zinc sites in proteins and other biomolecules can become redox-active when zinc is bound to the redox-active sulfur donor atom of cysteine. This interaction links zinc and redox metabolism, confers mobility on tightly bound zinc, and has implications for treating zinc deficiency. Third, the concept of zinc deficiency in blood as the only measure of an inadequate zinc status needs to be extended to zinc dyshomeostasis in cells because overwhelming the mechanisms controlling cellular zinc homeostasis can result in either not enough or too much available zinc. We need additional biomarkers of zinc status that determine cell-specific changes and perturbations of the system regulating cellular zinc, including functional deficits, and address the multiple genetic and environmental factors that can cause a conditioned zinc deficiency or overload. Considering the wider context of altered zinc availability in different organs, cells, and organelles impinges on whether zinc supplementation will be efficacious and adds another dimension to the already high health burden of zinc deficiency and its sequelae worldwide.

Zinc is an essential micronutrient that regulates a wide range of physiological processes, most often through zinc binding to protein cysteine residues. Despite being critical for modulation of protein function, the cysteine sites in the majority of the human proteome that are subject to zinc binding remain undefined. Here, we develop ZnCPT, a deep and quantitative mapping of the zinc-binding cysteine proteome. We define 6,173 zinc-binding cysteines, uncovering protein families across major domains of biology that are subject to constitutive or inducible zinc binding. ZnCPT enables systematic discovery of zinc-regulated structural, enzymatic, and allosteric functional domains. On this basis, we identify 52 cancer genetic dependencies subject to zinc binding and nominate malignancies sensitive to zinc-induced cytotoxicity. We discover a mechanism of zinc regulation over glutathione reductase (GSR), which drives cell death in GSR-dependent lung cancers. We provide ZnCPT as a resource for understanding mechanisms of zinc regulation of protein function.

Food security is defined as uninterrupted access to food that meets people's dietary needs. One essential trace element of a complete diet is zinc, which is vital for various processes, including growth, development, and the immune response. The estimated global prevalence of zinc deficiency is around 30%. Meat and meat products provide an abundant and also bioavailable source of zinc. However, in developing countries, access to meat is restricted, and in developed countries, meat consumption has declined for ethical and environmental reasons. The potential for zinc deficiency arises from (i) low concentrations of this element in plant-based diets, (ii) poor zinc absorption from plant-based food in the human intestine, and (iii) the risk of uptake of toxic metals together with essential ones. This review summarises the current knowledge concerning type 4 metallothioneins, which represent promising targets for zinc biofortification. We describe their place in the zinc route from soil to seed, their expression patterns, their role in plants, and their three-dimensional protein structure and how this affects their selectivity towards zinc. This review aims to provide a comprehensive theoretical basis for the potential use of type 4 plant metallothioneins to create zinc-biofortified crops.

Clostridioides difficile has been recognized as an important nosocomial pathogen that causes diarrheal disease as a consequence of antibiotic exposure and costs the healthcare system billions of dollars every year. C. difficile enters the host gut as dormant spores, germinates into vegetative cells, colonizes the gut, and produces toxins TcdA and/or TcdB, leading to diarrhea and inflammation. Spores are the primary transmission vehicle, while the toxins A and B directly contribute to the disease. Thus, toxin production and sporulation are the key traits that determine the success of C. difficile as a pathogen. Both toxins and spores are produced during the late stationary phase in response to various stimuli. This review provides a comprehensive analysis of the current knowledge on the molecular mechanisms, highlighting the regulatory pathways that interconnect toxin gene expression and sporulation in C. difficile. The roles of carbohydrates, amino acids and other nutrients and signals, in modulating these virulence traits through global regulatory networks are discussed. Understanding the links within the gene regulatory network is crucial for developing effective therapeutic strategies against C. difficile infections, potentially leading to targeted interventions that disrupt the co-regulation of toxin production and sporulation.

Chronic kidney disease (CKD) is now the world's top seventh cause of death from a non-communicable disease, and its incidence is projected to increase further as its major risk factors, including obesity, diabetes, hypertension, and non-alcoholic fatty liver disease (NAFLD), continue to rise. Current evidence has linked the increased prevalence of CKD, diabetes, hypertension, and NAFLD to chronic exposure to the metal pollutant cadmium (Cd). Exposure to Cd is widespread because diet is the main exposure route for most people. Notably, however, the health risk of dietary Cd exposure is underappreciated, and the existing tolerable exposure guidelines for Cd do not afford health protection. New health-protective exposure guidelines are needed. From one's diet, Cd is absorbed by the intestinal epithelium from where it passes through the liver and accumulates within the kidney tubular epithelial cells. Here, it is bound to metallothionine (MT), and as it is gradually released, it induces tubular damage, tubulointerstitial inflammation and fibrosis, and nephron destruction. The present review provides an update on our knowledge of the exposure levels of Cd that are found to be associated with CKD, NAFLD, and mortality from cardiovascular disease. It discusses the co-existence of hypertension and CKD in people environmentally exposed to Cd. It highlights nuclear and mitochondrial targeting and zinc deficiency as the universal cytotoxic mechanisms of Cd. Special emphasis is placed on the novel antioxidative function of zinc involving de novo heme biosynthesis and the induced expression of heme oxygenase-1 (HO-1). Other exogenous biomolecules with promising anti-Cd toxicity are highlighted.

The aim of this study was to explore the role of the ZnT9 protein in obesity-induced sperm maturation disorders in men. We generated a mouse model of obesity-induced weak spermatogenesis via a high-fat diet (HFD) for 10 weeks. In addition to the HFD, a 5-week intervention of salubrinal (SAL) (an inhibitor of endoplasmic reticulum stress) (1 mg/kg/day), ZnSO4 (15 mg/kg/day), and their combination was started at week 6, after which sperm viability and epididymal tissue damage were assessed. To investigate the role of the ZnT9 protein in spermatogenesis, the expression levels of the ZnT9 protein, endoplasmic reticulum stress (ERS)-related protein, Wnt pathway protein, and apoptosis-related protein in epididymal tissue were measured. Compared with those in the normal (N) group, the mice in the HFD group presented decreased sperm motility, damaged epididymal tissue, epididymal tissue showed decreased expression of ZnT9, β-catenin, LEF protein and mRNA, and increased expression of total cholesterol (TC) and triglycerides (TG), GRP78, Caspase-3, BAX protein and mRNA, as well as increased apoptosis as shown by TUNEL staining. Compared with the HFD group, HFD + ZnSO4 group, HFD + SAL group, and HFD + ZnSO4 + SAL groups resulted in reduced epididymal damage, improved decreased total cholesterol (TC) and triglycerides (TG), sperm viability, increased expression of ZnT9, β-catenin, LEF protein and mRNA, and decreased expression of GRP78, Caspase-3, and BAX protein and mRNA, as well as decreased apoptosis as shown by TUNEL staining in epididymal tissues. According to this study, obesity leads to elevated ERS and affects ZnT9 protein synthesis. Inhibition of the Wnt pathway ultimately leads to cell death and damage in epididymal tissue and decreased sperm viability.

Ran-binding domain-containing protein 2 (ZRANB2) is a zinc finger (ZF) protein that plays a key role in alternative splicing. ZRANB2 is composed of two ZF domains that contain four invariant cysteine residues per domain. ZRANB2 binds RNA targets that contain AGGUAA sequence motifs. Three constructs of ZRANB2, ZRANB2-ZF1 (first ZF domain), ZRANB2-ZF2 (second ZF domain), and ZRANB2-2D (both ZF domains), were isolated in the apo form and shown to bind Zn(II) via UV-visible-monitored competitive titrations with Co(II) as a spectroscopic probe. Zn binding to each construct led to the adoption of a limited secondary structure of each domain, as measured by circular dichroism (CD). Hydrogen-deuterium exchange coupled with mass spectrometry (HDX-MS) of the two-domain construct, ZRANB2-2D, revealed that both ZF domains adopt a more rigid structure upon Zn binding. Zn binding to the first ZF domain resulted in a greater decrease in the conformational dynamics than Zn binding to the second ZF domain. RNA binding to TRA2B pre-mRNA, a physiological splicing target, was measured by fluorescence anisotropy (FA), and high-affinity RNA binding was found to require Zn coordination to both domains. HDX-MS of ZRANB2-2D with TRA2B RNA as well as two optimized RNA sequences that contain a single and double AGGUAA hexamer revealed additional protection from H/D exchange for ZRANB2 in the presence of RNA. Here, greater protection was observed for the second ZF of ZRANB2-2D, suggesting a larger effect on conformational dynamics. A model for zinc-mediated RNA binding of ZRANB2 is proposed.

All 11 metallothionein protein-coding genes are located on human chromosome 16q13. It is unique among human genetics to have an entire pathway's genes clustered in a short chromosomal region. Since solid tumors, particularly high-grade serous ovarian cancer (HGSC), exhibit high rates of monoallelic aneuploidy, this region is commonly lost. Studies have not yet been performed to determine what vulnerability may be created in cancer cells with low metallothionein expression. Here, a screen of FDA-approved cancer small molecule drugs for those best targeting low metallothionein ovarian cancer was completed.

Screening methods were tested and compared using vehicle-treated negative controls and cadmium chloride, a positive control for cell loss selective for low metallothionein cells. CAOV3 cells, which are unique in their expression of only two metallothionein isoforms, were used, with or without shRNA knockdown of the predominantly expressed MT2A gene. A library of FDA-approved molecules was then screened.

The optimal assay utilized Hoechst 33342 nuclear staining and mechanized fluorescent microscope counting of cell content. Encorafenib, an RAF inhibitor, was identified as the most selective for enhanced cytotoxicity in MT2A knockdown cells compared to scrambled controls.

The nuclear stain Hoechst 33342, assessed by fluorescence microscopy, provides a low variance, moderate throughput platform for cancer cell loss screens. Low metallothionein ovarian cancer cells exhibit a vulnerability to the RAF inhibitor encorafenib.

Zinc is a vital trace element, yet its deficiency is common in various populations. This study addresses the gap in understanding zinc intake and its relationship with key nutritional parameters in a Colombian population. We analyzed data from 12,987 individuals, focusing on the daily intake of zinc, phytate, protein, and calcium, and used the phytate/zinc molar ratio as an input parameter in the Miller et al. (2013) model. This model was employed to estimate the total absorbed zinc (TAZ) and the fractional absorption of zinc (FAZ). Our findings highlight a general trend towards insufficient intake compared to the standards of the Institute of Medicine (IOM) and Colombia, with a significant percentage of the population falling below the estimated average requirement (EAR) and recommended daily allowance (RDA) for zinc, underscoring the need for targeted nutritional strategies. Our study contributes to a broader understanding of zinc nutrition and public health implications in Colombia, providing a basis for future dietary guidelines and health interventions.

Neurodegenerative diseases pose a significant health challenge for the elderly. The escalating presence of toxic metals and chemicals in the environment is a potential contributor to central nervous system dysfunction and the onset of neurodegenerative conditions. Transition metals play a crucial role in various pathophysiological mechanisms associated with prevalent neurodegenerative diseases such as Alzheimer's and Parkinson's. Given the ubiquitous exposure to metals from diverse sources in everyday life, the workplace, and the environment, most of the population faces regular contact with different forms of these metals. Disturbances in the levels and homeostasis of certain transition metals are closely linked to the manifestation of neurodegenerative disorders. Oxidative damage further exacerbates the progression of neurological consequences. Presently, there exists no curative therapy for individuals afflicted by neurodegenerative diseases, with treatment approaches primarily focusing on alleviating pathological symptoms. Within the realm of biologically active compounds derived from plants, flavonoids and curcuminoids stand out for their extensively documented antioxidant, antiplatelet, and neuroprotective properties. The utilization of these compounds holds the potential to formulate highly effective therapeutic strategies for managing neurodegenerative diseases. This review provides a comprehensive overview of the impact of abnormal metal levels, particularly copper, iron, and zinc, on the initiation and progression of neurodegenerative diseases. Additionally, it aims to elucidate the potential of fisetin and curcumin to inhibit or decelerate the neurodegenerative process.

Zinc is an essential element and important for inflammatory bowel disease patients. Herein, we aimed to elucidate the correlation between serum zinc concentration and various parameters, especially the disease activity index and endoscopic scores, in these patients. We measured serum zinc concentrations in 37 patients with Crohn's disease and 64 with ulcerative colitis and retrospectively analyzed patient characteristics, blood test values, disease activity, and endoscopic scores. Hypozincemia (<80 ‍μg/dl) was observed in 45.9% and 29.7% of patients with Crohn's disease and ulcerative colitis, respectively. Serum zinc concentration showed a weak negative correlation with Crohn's Disease Activity Index and C-reactive protein levels in Crohn's disease patients, and a weak negative correlation with white blood cell count in ulcerative colitis patients. The zinc concentrations in ulcerative colitis patients were significantly lower in Mayo endoscopic sub-score grade 2 than in grades 0 and 1. The simple endoscopic score for Crohn's disease moderately correlated with zinc concentration. In addition, serum zinc concentration showed a moderate correlation with serum albumin and Onodera's prognostic nutritional index in both Crohn's disease and ulcerative colitis patients. Serum zinc concentration clearly correlated with inflammatory bowel disease activity, endoscopy scores, and immunonutritional parameters, suggesting the importance of monitoring zinc levels.

Recent insights into the influence of nutrition on immune system components have driven the development of dietary strategies targeting the prevention and management of major metabolic-inflammatory diseases. This review summarizes the bidirectional relationship between nutrition and immunocompetence, beginning with an overview of immune system components and their functions. It examines the effects of nutritional status, dietary patterns, and food bioactives on systemic inflammation, immune cell populations, and lymphoid tissues, as well as their associations with infectious and chronic disease pathogenesis. The mechanisms by which key nutrients influence immune constituents are delineated, focusing on vitamins A, D, E, C, and B, as well as minerals including zinc, iron, and selenium. Also highlighted are the immunomodulatory effects of polyunsaturated fatty acids as well as bioactive phenolic compounds and probiotics, given their expanding relevance. Each section addresses the implications of nutritional and nutraceutical interventions involving these nutrients within the broader context of major infectious, metabolic, and inflammatory diseases. This review further underscores that, while targeted nutrient supplementation can effectively restore immune function to optimal levels, caution is necessary in certain cases, as it may increase morbidity in specific diseases. In other instances, dietary counseling should be integrated to ensure that therapeutic goals are achieved safely and effectively.

In the context of acute brain injuries, where zinc neurotoxicity and oxidative stress are acknowledged contributors to neuronal damage, we investigated the pivotal role of lysosomes as a potential protective mechanism. Our research commenced with an exploration of epidermal growth factor (EGF) and its impact on lysosomal dynamics, particularly its neuroprotective potential against zinc-induced cytotoxicity. Using primary mouse cerebrocortical cultures, we observed the rapid induction of EGFR endocytosis triggered by EGF, resulting in a transient increase in lysosomal vesicles. Furthermore, EGF stimulated lysosomal biogenesis, evident through elevated expression of lysosomal-associated membrane protein 1 (LAMP-1) and the induction and activation of prominent lysosomal proteases, particularly cathepsin B (CTSB). This process of EGFR endocytosis was found to promote lysosomal augmentation, thus conferring protection against zinc-induced lysosomal membrane permeabilization (LMP) and subsequent neuronal death. Notably, the neuroprotective effects and lysosomal enhancement induced by EGF were almost completely reversed by the inhibition of clathrin-mediated and caveolin-mediated endocytosis pathways, along with the disruption of retrograde trafficking. Furthermore, tyrosine kinase inhibition of EGFR nullified EGFR endocytosis, resulting in the abrogation of EGF-induced lysosomal upregulation and neuroprotection. An intriguing aspect of our study is the successful replication of EGF's neuroprotective effects through the overexpression of LAMP-1, which significantly reduced zinc-induced LMP and cell death, demonstrated in both primary mouse cerebrocortical neuronal cultures and human embryonic kidney (HEK) cells. Our research extended beyond zinc-induced neurotoxicity, as we observed EGF's protective effects against other oxidative stressors linked to intracellular zinc release, including hydrogen peroxide (H2O2) and 1-methyl-4-phenylpyridinium ion (MPP+). Collectively, our findings unveil the intricate interplay between EGF-triggered EGFR endocytosis, lysosomal upregulation, an increase in the regulatory capacity for zinc homeostasis, and the subsequent alleviation of zinc-induced neurotoxicity. These results present promising avenues for therapeutic interventions to enhance neuroprotection by targeting lysosomal augmentation.

Metalloproteins widely exist in biology, playing pivotal roles in diverse life processes. Meanwhile, molecular dynamics (MD) simulations based on classical force fields has emerged as an important tool in scientific research. Partial charges are critical parameters within classical force fields and usually derived from quantum mechanical (QM) calculations. However, QM calculations are often time-consuming and prone to basis set dependence. Alternatively, fluctuating charge (FQ) models offer another avenue for partial charge derivation, which has significant speed advantages and can be used for large-scale screening. Building upon our previous work, which introduced an FQ model for zinc-containing complexes, herein we extend this model to include additional 3d transition metals which are important to the life sciences, namely chromium, manganese, iron, cobalt, and nickel. Employing CM5 charges as target for parametrization, our FQ model accurately reproduces partial charges for 3d metal complexes featuring biologically relevant ligands. Furthermore, by using atomic charges derived by our FQ model, MD simulations have been performed. These charges showed excellent performance in simulating proteomic metal sites housing multiple metal ions, specifically, a metalloprotein containing an iron-sulfur cluster and another containing a dimanganese metal site, showcasing comparable performance to those of RESP charges. We anticipate that our study can accelerate the parametrization of atomic charges for metalloproteins featuring 3d transition metals, thereby facilitating simulations of relevant systems.

Selenium and zinc are essential trace elements known to regulate cellular processes including redox homeostasis. During inflammation, circulating selenium and zinc concentrations are reduced in parallel, but underlying mechanisms are unknown. Accordingly, we modulated the zinc and selenium supply of HepG2 cells to study their relationship.

HepG2 cells were supplied with selenite in combination with a short- or long-term zinc treatment to investigate intracellular concentrations of selenium and zinc together with biomarkers describing their status. In addition, the activation of the redox-sensitive transcription factor NRF2 was analyzed.

Zinc not only increased the nuclear translocation of NRF2 after 2 to 6 h but also enhanced the intracellular selenium content after 72 h, when the cells were exposed to both trace elements. In parallel, the activity and expression of the selenoprotein thioredoxin reductase 1 (TXNRD1) increased, while the gene expression of other selenoproteins remained unaffected or was even downregulated. The zinc effects on the selenium concentration and TXNRD activity were reduced in cells with stable NRF2 knockdown in comparison to control cells.

This indicates a functional role of NRF2 in mediating the zinc/selenium crosstalk and provides an explanation for the observed unidirectional behavior of selenium and zinc.

In addition to the essential structural and catalytic functions of zinc, evolution has adopted synaptic zinc as a neuromodulator. In the brain, synaptic zinc is released primarily from glutamatergic neurons, notably in the neocortex, hippocampus, amygdala, and auditory brainstem. In these brain areas, synaptic zinc is essential for neuronal and sensory processing fine-tuning. But what niche does zinc fill in neural signaling that other neuromodulators do not? Here, we discuss the evolutionary history of zinc as a signaling agent and its eventual adoption as an essential neuromodulator in the mammalian brain. We then attempt to describe the unique roles that zinc has carved out of the vast and diverse landscape of neuromodulators.

This article describes intracellular zinc-induced excimer emission and tuning of self-assembly from L-tryptophan-pyrene conjugate (1). The zinc-guided excimer formation is due to the interaction of the pyrene moiety in an excited state. AFM studies show the structural modification in the supramolecular nano-assembly of 1 from dome-shaped to porous surface after complexation with zinc ions. Further, the interaction of 1 with Zn(II) ion is also studied using DFT, Job's plot, NMR titration and HRMS. The results of Zn(II) ion determination in natural water samples and RAW 264.7 cells demonstrate the practical utility of 1.

Zinc (Zn) is an essential trace element; it exhibits a plethora of physiological properties and biochemical functions. It plays a pivotal role in regulating the cell cycle, apoptosis, and DNA organization, as well as in protein, lipid, and carbohydrate metabolism. Among other important processes, Zn plays an essential role in reproductive health. The ZIP and ZnT proteins are responsible for the mobilization of Zn within the cell. Zn is an inert antioxidant through its interaction with a variety of proteins and enzymes to regulate the redox system, including metallothioneins (MTs), metalloenzymes, and gene regulatory proteins. The role of Zn in the reproductive system is of great importance; processes, such as spermatogenesis and sperm maturation that occur in the testicle and epididymis, respectively, depend on this element for their development and function. Zn modulates the synthesis of androgens, such as testosterone, for these reproductive processes, so Zn deficiency is related to alterations in sperm parameters that lead to male infertility.

Diabetes mellitus is a global health problem and a major contributor to mortality and morbidity. The management of this condition typically involves using oral antidiabetic medication, insulin, and appropriate dietary modifications, with a focus on macronutrient intake. However, several human studies have indicated that a deficiency in micronutrients, such as zinc, can be associated with insulin resistance as well as greater glucose intolerance. Zinc serves as a chemical messenger, acts as a cofactor to increase enzyme activity, and is involved in insulin formation, release, and storage. These diverse functions make zinc an important trace element for the regulation of blood glucose levels. Adequate zinc levels have also been shown to reduce the risk of developing diabetic complications. This review article explains the role of zinc in glucose metabolism and the effects of its inadequacy on the development, progression, and complications of diabetes mellitus. Furthermore, it describes the impact of zinc supplementation on preventing diabetes mellitus. The available information suggests that zinc has beneficial effects on the management of diabetic patients. Although additional large-scale randomized clinical trials are needed to establish zinc's clinical utility further, efforts should be made to increase awareness of its potential benefits on human health and disease.

For continuous pumping of blood, the heart needs a constant supply of energy (ATP) that is primarily met via oxidative phosphorylation in the mitochondria of cardiomyocytes. However, sustained high rates of electron transport for energy conversion redox reactions predisposes the heart to the production of reactive oxygen species (ROS) and oxidative stress. Mitochondrial ROS are fundamental drivers of responses to environmental stressors including metals but knowledge of how combinations of metals alter mitochondrial ROS homeodynamics remains sparse. We explored the effects and interactions of binary mixtures of copper (Cu), cadmium (Cd), and zinc (Zn), metals that are common contaminants of aquatic systems, on ROS (hydrogen peroxide, H2O2) homeodynamics in rainbow trout (Oncorhynchus mykiss) heart mitochondria. Isolated mitochondria were energized with glutamate-malate or succinate and exposed to a range of concentrations of the metals singly and in equimolar binary concentrations. Speciation analysis revealed that Cu was highly complexed by glutamate or Tris resulting in Cu2+ concentrations in the picomolar to nanomolar range. The concentration of Cd2+ was 7.2-7.5 % of the total while Zn2+ was 15 % and 21 % of the total during glutamate-malate and succinate oxidation, respectively. The concentration-effect relationships for Cu and Cd on mitochondrial H2O2 emission depended on the substrate while those for Zn were similar during glutamate-malate and succinate oxidation. Cu + Zn and Cu + Cd mixtures exhibited antagonistic interactions wherein Cu reduced the effects of both Cd and Zn, suggesting that Cu can mitigate oxidative distress caused by Cd or Zn. Binary combinations of the metals acted additively to reduce the rate constant and increase the half-life of H2O2 consumption while concomitantly suppressing thioredoxin reductase and stimulating glutathione peroxidase activities. Collectively, our study indicates that binary mixtures of Cu, Zn, and Cd act additively or antagonistically to modulate H2O2 homeodynamics in heart mitochondria.

(1) Background: Multiple sclerosis (MS) is a chronic, complex, and demyelinating disease closely associated with altered levels of trace elements. Although the first studies into the role of trace elements in MS were published in the 1970s, for five decades it has remained unknown whether trace elements can be part of this heterogeneous neurological disease. (2) Materials and methods: To drive toward at a potential solution, we conducted a systematic review and meta-analysis to elucidate whether there were differences in circulating levels of neurologically important essential trace elements (Zn, Fe, Co, Cu, Mn, and Se) between MS cases and controls. (3) Results: This study revealed significantly lower serum/plasma Zn and Fe levels and higher Cu levels in MS-affected individuals compared to controls. At the same time, no significant differences were found between the MS cases and controls regarding their serum/plasma levels of Co, Mn, or Se. Thus, the loss of Fe and Zn should be considered in supplementation/nutrition strategies for MS patients. On the other hand, since high serum Cu levels indicate a burden on the bloodstreams of MS patients, Cu should be excluded from mineral supplement strategies. Furthermore, all three trace elements (Fe, Zn, and Cu) should be considered from an etiological point of view, and, most importantly, their levels in the bloodstreams of MS patients should be monitored. (4) Conclusions: This study highlights the way for personalized and targeted strategies in the management of MS.

The gasotransmitter hydrogen sulfide (H2S) is thought to be involved in the post-translational modification of cysteine residues to produce reactive persulfides. A persulfide-specific chemoselective proteomics approach with mammalian cells has identified a broad range of zinc finger (ZF) proteins as targets of persulfidation. Parallel studies with isolated ZFs show that persulfidation is mediated by ZnII, O2, and H2S, with intermediates involving oxygen- and sulfur-based radicals detected by mass spectrometry and optical spectroscopies. A small molecule ZnII complex exhibits analogous reactivity with H2S and O2, giving a persulfidated product. These data show that ZnII is not just a biological structural element, but also plays a critical role in mediating H2S-dependent persulfidation. ZF persulfidation appears to be a general post-translational modification and a possible conduit for H2S signaling. This work has implications for our understanding of H2S-mediated signaling and the regulation of ZFs in cellular physiology and development.

Giardiasis and zinc deficiency have been identified as serious health problems worldwide. Although Zn depletion is known to occur in giardiasis, no work has investigated whether changes occur in brain structures.

Three groups of gerbils were used: control (1), orogastrically inoculated on day 3 after birth with trophozoites of two isolates of Giardia intestinalis (HGINV/WB) group (2 and 3). Estimates were made at five ages covering: establishment of infection, Giardia population growth, natural parasite clearance and a post-infection age. QuantiChrome zinc assay kit, cresyl violet staining and TUNEL technique were used.

A significant decrease (p<0.01) in tissue zinc was observed and persisted after infection. Cytoarchitectural changes were observed in 75% of gerbils in the HGINV or WB groups. Ectopic pyramidal neurons were found in the cornus ammonis (CA1-CA3). At 60 and 90 days of age loss of lamination was clearly visible in CA1. In the dentate gyrus (DG), thinning of the dorsal lamina and abnormal thickening of the ventral lamina were observed from 30 days of age. In the cerebellum, we found an increase (p<0.01) in the thickness of the external granular layer (EGL) at 14 days of age that persisted until day 21 (C 3 ± 0.3 μm; HGINV 37 ± 5 μm; WB 28 ± 3 μm); Purkinje cell population estimation showed a significant decrease; a large number of apoptotic somas were observed scattered in the molecular layer; in 60 and 90 days old gerbils we found granular cell heterotopia and Purkinje cell ectopia. The pattern of apoptosis was different in the cerebellum and hippocampus of parasitized gerbils.

The morphological changes found suggest that neuronal migration is affected by zinc depletion caused by giardiasis in early postnatal life; for the first time, the link between giardiasis-zinc depletion and damaged brain structures is shown. This damage may explain the psychomotor/cognitive delay associated with giardiasis. These findings are alarming. Alterations in zinc metabolism and signalling are known to be involved in many brain disorders, including autism.

Zinc is a ubiquitous contaminant in many buffers, purified products and common labware that has previously been suggested to impact on the results of functional GlyR studies and may inadvertently cause the effectiveness of some GlyR modulators to be over-estimated. This could greatly impact the assessment of potential drug-candidates and contribute to the reduced effectiveness of compounds that reach clinical stages. This is especially true for GlyR modulators being developed for pain therapeutics due to the changes in spinal zinc concentrations that have been observed during chronic pain conditions. In this study we use two-electrode voltage clamp electrophysiology to evaluate the metal chelators tricine and Ca-EDTA, and show that tricine produces inhibitory effects at GlyRα1 that are not mediated by zinc. We also utilized the zinc insensitive W170S mutation as a tool to validate metal chelators and confirm that zinc contamination has not impacted the examination of lipid modulators previously developed by our lab. This study helps to further develop methods to negate the impact of contaminating zinc in functional studies of GlyRs which should be incorporated into future studies that seek to characterize the activity of novel modulators at GlyRs.

Zinc (Zn2+) plays roles in structure, catalysis, and signaling. The majority of cellular Zn2+ is bound by proteins, but a fraction of total Zn2+ exists in a labile form. Here, we present a protocol for measuring labile cytosolic Zn2+ using an in situ calibration of a genetically encoded Förster resonance energy transfer (FRET) sensor. We describe steps for producing buffered Zn2+ solutions for performing an imaging-based calibration and analyzing the imaging data generated to determine labile Zn2+ concentration in single cells. For complete details on the use and execution of this protocol, please refer to Rakshit and Holtzen et al.1.

The exchangeable Zn2+ pool in cells is not static but responds to perturbations as well as fluctuates naturally through the cell cycle. Here, we present a protocol to carry out long-term live-cell imaging of cells expressing a cytosolic Zn2+ sensor. We then describe how to track cells using the published pipeline EllipTrack and how to analyze the single-cell traces to determine changes in labile Zn2+ in response to perturbation. For complete details on the use and execution of this protocol, please refer to Rakshit and Holtzen et al.1.

Carcass traits are essential economic traits in the commercial pig industry. However, the genetic mechanism of carcass traits is still unclear. In this study, we performed a genome-wide association study (GWAS) based on the specific-locus amplified fragment sequencing (SLAF-seq) to study seven carcass traits on 223 four-way intercross pigs, including dressing percentage (DP), number of ribs (RIB), skin thinkness (ST), carcass straight length (CSL), carcass diagonal length (CDL), loin eye width (LEW), and loin eye thickness (LET).

A total of 227,921 high-quality single nucleotide polymorphisms (SNPs) were detected to perform GWAS. A total of 30 SNPs were identified for seven carcass traits using the mixed linear model (MLM) (p < 1.0 × 10- 5), of which 9 SNPs were located in previously reported quantitative trait loci (QTL) regions. The phenotypic variation explained (PVE) by the significant SNPs was from 2.43 to 16.32%. Furthermore, 11 candidate genes (LYPLAL1, EPC1, MATN2, ZFAT, ZBTB10, ZNF704, INHBA, SMYD3, PAK1, SPTBN2, and ACTN3) were found for carcass traits in pigs.

The GWAS results will improve our understanding of the genetic basis of carcass traits. We hypothesized that the candidate genes associated with these discovered SNPs would offer a biological basis for enhancing the carcass quality of pigs in swine breeding.

Hydrogen sulfide (H2S) is an endogenous gasotransmitter that signals via persulfidation. There is evidence that the cysteine residues of certain zinc finger (ZF) proteins, a common type of cysteine rich protein, are modified to persulfides by H2S. To determine how frequently ZF persulfidation occurs in cells and identify the types of ZFs that are persulfidated, persulfide specific proteomics data were evaluated. 22 datasets from 16 studies were analyzed via a meta-analysis approach. Persulfidated ZFs were identified in a range of eukaryotic species, including Homo sapiens, Mus musculus, Rattus norvegicus, Arabidopsis thaliana, and Emiliania huxley (single-celled phytoplankton). The types of ZFs identified for each species encompassed all three common ZF ligand sets (4-cysteine, 3-cysteine-1-histidine, and 2-cysteine-2-hisitidine), indicating that persulfidation of ZFs is broad. Overlap analysis between different species identified several common ZFs. GO and KEGG analysis identified pathway enrichment for ubiquitin-dependent protein catabolic process and viral carcinogenesis. These collective findings support ZF persulfidation as a wide-ranging PTM that impacts all classes of ZFs.

The stable isotope composition of zinc (δ66Zn), which is an essential trace metal for many biological processes in vertebrates, is increasingly used in ecological, archeological, and paleontological studies to assess diet and trophic level discrimination among vertebrates. However, the limited understanding of dietary controls and isotopic fractionation processes on Zn isotope variability in animal tissues and biofluids limits precise dietary reconstructions. The current study systematically investigates the dietary effects on Zn isotope composition in consumers using a combined controlled feeding experiment and box-modeling approach. For this purpose, 21 rats were fed one of seven distinct animal- and plant-based diets and a total of 148 samples including soft and hard tissue, biofluid, and excreta samples of these individuals were measured for δ66Zn. Relatively constant Zn isotope fractionation is observed across the different dietary groups for each tissue type, implying that diet is the main factor controlling consumer tissue δ66Zn values, independent of diet composition. Furthermore, a systematic δ66Zn diet-enamel fractionation is reported for the first time, enabling diet reconstruction based on δ66Zn values from tooth enamel. In addition, we investigated the dynamics of Zn isotope variability in the body using a box-modeling approach, providing a model of Zn isotope homeostasis and inferring residence times, while also further supporting the hypothesis that δ66Zn values of vertebrate tissues are primarily determined by that of the diet. Altogether this provides a solid foundation for refined (paleo)dietary reconstruction using Zn isotopes of vertebrate tissues.

N-(9-anthracenylmethyl)-N-(2-pyridinylmethyl)-2-pyridinemethanamine (ADPA) as a specific ion sensor for Zn2+ has been widely applied. Although the photo-induced electron transfer (PET) mechanism was proposed previously, its fluorescence-enhanced effect still remains somewhat ambiguous, according to unknown influences of non-radiative energy decay pathways, such as intersystem crossing and internal conversion. Herein, a thorough study using density functional theory has been performed for low-lying electronic states of the ADPA monomer and hydrated ADPA-Zn2+ complex. Based on interfragment charge transfer analyses, we quantitatively calculated the amount of transferred electrons in the monomer and complex, providing solid evidences for the PET mechanism and in line with the conclusion of frontier molecular orbital analyses. Moreover, the ISC process of S1→T2 was confirmed to play a considerable role in the excitation energy relaxation process of the ADPA monomer, but this influence was significantly suppressed in the hydrated ADPA-Zn2+ complex. These results provide additional clues for the design of new metal ion-specific fluorescence probes.

Zinc serves critical catalytic, regulatory, and structural roles. Hosts and their resident gut microbiota both require zinc, leading to competition, where a balance must be maintained. This systematic review examined evidence on dietary zinc and physiological status (zinc deficiency or high zinc/zinc overload) effects on gut microbiota. This review was conducted according to PRISMA (Preferred Reporting Items for Systematic reviews and Meta-Analyses) guidelines and registered in PROSPERO (CRD42021250566). PubMed, Web of Science, and Scopus databases were searched for in vivo (animal) studies, resulting in eight selected studies. Study quality limitations were evaluated using the SYRCLE risk of bias tool and according to ARRIVE guidelines. The results demonstrated that zinc deficiency led to inconsistent changes in α-diversity and short-chain fatty acid production but led to alterations in bacterial taxa with functions in carbohydrate metabolism, glycan metabolism, and intestinal mucin degradation. High dietary zinc/zinc overload generally resulted in either unchanged or decreased α-diversity, decreased short-chain fatty acid production, and increased bacterial metal resistance and antibiotic resistance genes. Additional studies in human and animal models are needed to further understand zinc physiological status effects on the intestinal microbiome and clarify the applicability of utilizing the gut microbiome as a potential zinc status biomarker.

The relationship of exposure to benzo[a]pyrene (BaP) with lung cancer risk has been firmly established, but whether this association could be modified by other environmental or genetic factors remains to be explored. To investigate whether and how zinc (Zn) and genetic predisposition modify the association between BaP and lung cancer, we performed a case-cohort study with a 5.4-year median follow-up duration, comprising a representative subcohort of 1399 participants and 359 incident lung cancer cases. The baseline concentrations of benzo[a]pyrene diol epoxide-albumin adduct (BPDE-Alb) and Zn were quantified. We also genotyped the participants and computed the polygenic risk score (PRS) for lung cancer. Our findings indicated that elevated BPDE-Alb and PRS were linked to increased lung cancer risk, with the HR (95%CI) of 1.54 (1.36, 1.74) per SD increment in ln-transformed BPDE-Alb and 1.27 (1.14, 1.41) per SD increment in PRS, but high plasma Zn level was linked to a lower lung cancer risk [HR (95%CI)=0.77 (0.66, 0.91) per SD increment in ln-transformed Zn]. There was evidence of effect modification by Zn on BaP-lung cancer association (P for multiplicative interaction = 0.008). As Zn concentrations increased from the lowest to the highest tertile, the lung cancer risk per SD increment in ln-transformed BPDE-Alb decreased from 2.07 (1.48, 2.89) to 1.33 (0.90, 1.95). Additionally, we observed a significant synergistic interaction of BPDE-Alb and PRS [RERI (95%CI) = 0.85 (0.03, 1.67)], with 42% of the incident lung cancer cases among individuals with high BPDE-Alb and high PRS attributable to their additive effect [AP (95%CI) = 0.42 (0.14, 0.69)]. This study provided the first prospective epidemiological evidence that Zn has protective effect against BaP-induced lung tumorigenesis, whereas high genetic risk can enhance the harmful effect of BaP. These findings may provide novel insight into the environment-environment and environment-gene interaction underlying lung cancer development, which may help to develop prevention and intervention strategies to manage BaP-induced lung cancer.

Zinc (Zn) is the second most abundant metal in the human body and is essential for the function of 10% of all proteins. As metals cannot be synthesized or degraded, they must be assimilated from the diet by specialized transport proteins, which unfortunately also provide an entry route for the toxic metal pollutant cadmium (Cd). The intestinal absorption of Zn depends on the composition of food that is consumed, firstly the amount of Zn itself and then the quantity of other food constituents such as phytate, protein, and calcium (Ca). In cells, Zn is involved in the regulation of intermediary metabolism, gene expression, cell growth, differentiation, apoptosis, and antioxidant defense mechanisms. The cellular influx, efflux, subcellular compartmentalization, and trafficking of Zn are coordinated by transporter proteins, solute-linked carriers 30A and 39A (SLC30A and SLC39A), known as the ZnT and Zrt/Irt-like protein (ZIP). Because of its chemical similarity with Zn and Ca, Cd disrupts the physiological functions of both. The concurrent induction of a Zn efflux transporter ZnT1 (SLC30A1) and metallothionein by Cd disrupts the homeostasis and reduces the bioavailability of Zn. The present review highlights the increased mortality and the severity of various diseases among Cd-exposed persons and the roles of Zn and other transport proteins in the manifestation of Cd cytotoxicity. Special emphasis is given to Zn intake levels that may lower the risk of vision loss and bone fracture associated with Cd exposure. The difficult challenge of determining a permissible intake level of Cd is discussed in relation to the recommended dietary Zn intake levels.

Zinc ions (Zn2+) play a key role in maintaining and regulating protein structures and functions. To better understand the intracellular Zn2+ homeostasis and signaling role, various fluorescent sensors have been developed that allow the monitoring of Zn2+ concentrations and bioimaging in live cells in real time. This review highlights the recent development of organic fluorescent probes for the detection and imaging of intracellular Zn2+, including the design and construction of the probes, fluorescent response mechanisms, and their applications to intracellular Zn2+ detection and imaging on-site. Finally, the current challenges and prospects are discussed.