The Smad transcription factors are well known for their role at the core of transforming growth factor-β (TGF-β) signalling. However, recent evidence shows that the Smad transcription factors play a vital role downstream of other classes of receptors including G protein-coupled receptors (GPCR). The versatility of Smad transcription factors originated from the two regions that can be differently activated by the TGF-β receptor superfamily or through the recruitment of intracellular kinases stimulated by other receptors classes such as GPCRs. The classic GPCR signalling cascade is further expanded to conditional adoption of the Smad transcription factor under the stimulation of Akt, demonstrating the unique involvement of the Smad transcription factor in GPCR signalling pathways in disease environments. In this review, we provide a summary of the signalling pathways of the Smad transcription factors as an important downstream mediator of GPCRs, presenting exciting opportunities for discovering new therapeutic targets for diseases.

The dysregulation of the transforming growth factor β (TGF-β) signaling pathway plays a critical role in the onset and progression of several diseases, including cancer. Notably, TGF-β has emerged as a significant barrier to effective outcomes in cancer immunotherapies, particularly those using immune checkpoint inhibitors. In response to this challenge, small-molecule inhibitors targeting the TGF-β receptor I (TGF-βRI) have garnered attention as promising candidates for modulating the TGF-β signaling pathway. This comprehensive review focuses on the development of small-molecule inhibitors targeting TGF-βRI. We provide a detailed analysis of the structural biology of TGF-βRI, highlighting key binding interactions and structural insights derived from high-resolution X-ray crystal structures. Additionally, we review the current landscape of TGF-βRI inhibitors in clinical trials, including eight promising inhibitors, and discuss their mechanisms of action, selectivity, and therapeutic potential. Our investigation extends to the patent literature, summarizing over 2 decades of innovation from leading pharmaceutical companies, spanning January 2000-May 2024. This consolidated structural and biochemical knowledge aims to facilitate the design of next-generation TGF-βRI inhibitors, addressing unmet clinical needs in oncology and fibrosis treatment. The synergistic potential of combining TGF-βRI and immune checkpoint inhibitors is also explored, offering promising avenues for enhancing cancer immunotherapy efficacy.

The activation of hepatic stellate cells (HSCs) from a quiescent state is a cause of liver fibrosis and a therapeutic target. HSCs are resident mesenchymal cells located in the space of Disse, exhibiting specialized morphological characteristics such as a stellate shape, large lipid droplets, and direct adhesions to hepatocytes via microprojections called HSC spines. Morphological alterations in HSCs play a crucial role in initiating their activation. However, the mechanisms regulating these changes remain unexplored. In this study, we analyzed the morphological alterations associated with HSC activation in vivo using carbon tetrachloride treatment and identified the key factors regulating these changes in vitro. Following carbon tetrachloride treatment, HSCs exhibited shortened cell processes and HSC spines, adopting an oval shape. Subsequently, the HSCs underwent further morphological changes into two activated forms: flattened and complex shapes. In vitro, activation of cell division cycle 42 (Cdc42) maintained the morphological characteristics of quiescent HSCs. Cdc42 activation in HSC cell lines inhibited the expression of markers associated with activated HSCs. Cdc42 inhibitor treatment in vivo prevented quiescent HSCs from maintaining their morphological characteristics and hindered activated HSCs from reverting to the quiescent state. In addition, HSCs around fibrotic areas in the human liver exhibited morphological alterations indicative of early activation. These findings demonstrate that Cdc42 is a crucial regulator of morphological and molecular alterations associated with HSC activation, identifying it as a novel target for the development of therapeutic agents against liver fibrosis.NEW & NOTEWORTHY The activation of hepatic stellate cells from a quiescent state is a cause and a therapeutic target for liver fibrosis. Morphological alterations in the hepatic stellate cells play a critical role in initiating their activation. However, the mechanisms that regulate these alterations remain unexplored. Our results indicate that cell division cycle 42 is a crucial regulator of hepatic stellate cell activation and a novel target for the development of therapeutic agents against liver fibrosis.

TGM6 is a natural antagonist of mammalian TGF-β signaling produced by the murine helminth parasite Heligmosomoides polygyrus. It differs from the previously described agonist, TGM1 (TGF-β Mimic-1), in that it lacks domains 1/2 that bind TGFBR1. It nonetheless retains TGFBR2 binding through domain 3 and potently inhibits TGF-β signaling in fibroblasts and epithelial cells, but does not inhibit TGF-β signaling in T cells, consistent with divergent domains 4/5 and an altered co-receptor binding preference. The crystal structure of TGM6 bound to TGFBR2 reveals an interface remarkably similar to that of TGF-β with TGFBR2. Thus, TGM6 has adapted its structure to mimic TGF-β, while engaging a distinct co-receptor to direct antagonism to fibroblasts and epithelial cells. The co-expression of TGM6, along with immunosuppressive TGMs that activate the TGF-β pathway, may minimize fibrotic damage to the host as the parasite progresses through its life cycle from the intestinal lumen to submucosa and back again. The co-receptor-dependent targeting of TGFBR2 by the parasite provides a template for the development of therapies for targeting the cancer- and fibrosis-promoting activities of the TGF-βs in humans.

Cancer persists as a ubiquitous global challenge despite the remarkable advances. It is caused by uncontrolled cell growth and metastasis. The Transforming Growth Factor-beta (TGF-β) signaling pathway is considered a primary regulator of various normal physiological processes in the human body. Recently, factors determining the nature of TGF-β response have received attention, specifically its signaling pathway which can be an attractive therapeutic target for various cancer treatments. The TGF-β receptor is activated by its ligands and undergoes transduction of signals via canonical (SMAD dependent) or non-canonical (SMAD independent) signaling pathways regulating several cellular functions. Furthermore, the cross talk of the TGF-β signaling pathway cross with other signaling pathways has shown the controlled regulation of cellular functions. This review highlights the cross talk between various major signaling pathways and TGF-β. These signaling pathways include Wnt, NF-κB, PI3K/Akt, and Hedgehog (Hh). TGF-β signaling pathway has a dual role at different stages. It can suppress tumor formation at early stages and promote progression at advanced stages. This complex behaviour of TGF-β has made it a promising target for therapeutic interventions. Moreover, many strategies have been designed to control TGF-β signaling pathways at different levels, inhibiting tumor-promoting while enhancing tumor-suppressive effects, each with unique molecular mechanisms and clinical implications. This review also discusses various therapeutic inhibitors including ligand traps, small molecule inhibitors (SMIs), monoclonal antibodies (mAbs), and antisense oligonucleotides which target specific components of TGF-β signaling pathway to inhibit TGF-β signaling and are studied in both preclinical and clinical trials for different types of cancer. The review also highlights the prospect of TGF-β signaling in normal physiology and in the case of dysregulation, TGF-β inhibitors, and different therapeutic effects in cancer therapy along with the perspective of combinational therapies to treat cancer.

Non-Small Cell lung cancer (NSCLC) is known for its fast progression, metastatic potency, and a leading cause of mortality globally. At diagnosis, approximately 30-40% of NSCLC patients already present with metastasis. Epithelial to mesenchymal transition (EMT) is a developmental program implicated in cancer progression and metastasis. Transforming Growth Factor-β (TGFβ) and its signalling plays a prominent role in orchestrating the process of EMT and cancer metastasis. In present study, a comprehensive molecular interaction map of TGFβ induced EMT in NSCLC was developed through an extensive literature survey. The map encompasses 394 species interconnected through 554 reactions, representing the relationship and complex interplay between TGFβ induced SMAD dependent and independent signalling pathways (PI3K/Akt, Wnt, EGFR, JAK/STAT, p38 MAPK, NOTCH, Hypoxia). The map, built using Cell Designer and compliant with SBGN and SBML standards, was subsequently translated into a logical modelling framework using CaSQ and dynamically analysed with Cell Collective. These analyses illustrated the complex regulatory dynamics, capturing the known experimental outcomes of TGFβ induced EMT in NSCLC including the co-existence of hybrid EM phenotype during transition. Hybrid EM phenotype is known to contribute for the phenotypic plasticity during metastasis. Network-based analysis identified the crucial network level properties and hub regulators, while the transcriptome-based analysis cross validated the prognostic significance and clinical relevance of key regulators. Overall, the map developed and the subsequent analyses offer deeper understanding of the complex regulatory network governing the process of EMT in NSCLC.

Transforming growth factor-beta (TGF-β) plays a pivotal role in breast development by modulating tissue composition during the developmental phase. The TGFβ type II receptor (TGFβ RII) is implicated in breast cancer and represents a valuable therapeutic target. Due to the off-target side effects of many existing TGFβI/TGFβ RII inhibitors, a more targeted approach to drug discovery is necessary. This study used computational modeling and molecular dynamics simulations to screen the ChemBridge small molecule library against TGFβ RII.

This study employed high-throughput virtual screening, molecular dynamics simulations, and binding free energy calculations to identify potential inhibitors targeting TGF-β RII. MDA-MB 231 and MCF-7 breast cancer cells were used in anti-proliferative, tans-endothelial migration, and flow cytometric assays for in vitro validations.

We identified 8-(2-methylphenyl)-9H-benzo[f]indeno[2,1-c]quinolin-9-one (C-5635020) as a potent and selective inhibitor. Protein-ligand modeling analysis revealed that C-5635020 targets the kinase domain of TGFβ RII with superior binding affinities compared to the standard drug, staurosporine. Computational results suggest that C-5635020 selectively binds and inhibits TGFβ RII activity, thereby controlling cell proliferation in breast cancer. In vitro, experiments corroborated these predictions, where C-5635020 inhibited TGFβ RII and p-Smad 2/3 positive population in MDAMB-231 and MCF-7 cells. The compound dose-dependently inhibited cell proliferation, trans-endothelial migration, and increased apoptosis in both breast cancer cell lines.

The strong binding affinity, stability, and favorable thermodynamics of C-5635020 with established in vitro efficacy highlight its potential as a lead compound for further preclinical and clinical developments for breast cancer treatment.

Smads and their transcription factor partners mediate the transcriptional responses of target cells to secreted ligands of the transforming growth factor-β (TGF-β) family, including those of the conserved bone morphogenetic protein (BMP) family, yet only a small number of direct target genes have been well characterized. In C. elegans, the BMP2/4 ortholog DBL-1 regulates multiple biological functions, including body size, via a canonical receptor-Smad signaling cascade. Here, we identify functional binding sites for SMA-3/Smad and its transcriptional partner SMA-9/Schnurri based on ChIP-seq peaks (identified by modEncode) and expression differences of nearby genes identified from RNA-seq analysis of corresponding mutants. We found that SMA-3 and SMA-9 have both overlapping and unique target genes. At a genome-wide scale, SMA-3/Smad acts as a transcriptional activator, whereas SMA-9/Schnurri direct targets include both activated and repressed genes. Mutations in sma-9 partially suppress the small body size phenotype of sma-3, suggesting some level of antagonism between these factors and challenging the prevailing model for Schnurri function. Functional analysis of target genes revealed a novel role in body size for genes involved in one-carbon metabolism and in the endoplasmic reticulum (ER) secretory pathway, including the disulfide reductase dpy-11. Our findings indicate that Smads and SMA-9/Schnurri have previously unappreciated complex genetic and genomic regulatory interactions that in turn regulate the secretion of extracellular components like collagen into the cuticle to mediate body size regulation.

The incidence of early-onset colorectal cancer (EOCRC) has been rising at an alarming rate in the USA, and EOCRC disproportionately affects racial/ethnic minorities. Here, we construct comprehensive profiles of EOCRC DNA methylomes at base-pair resolution for a cohort of Hispanic and African American patients.

We show the epigenetic landscape of these EOCRC patients differs from that of late-onset colorectal cancer patients, and methylation canyons in EOCRC tumor tissue preferentially overlapped genes in cancer-related pathways. Furthermore, we identify epigenetic alterations in metabolic genes that are specific to our racial/ethnic minority EOCRC cohort but not Caucasian patients from TCGA. Top genes differentially methylated between these cohorts included the obesity-protective MFAP2 gene as well as cancer risk susceptibility genes APOL3 and RNASEL.

In this study, we provide to the scientific community high-resolution DNA methylomes for a cohort of EOCRC patients from underrepresented populations. Our exploratory findings in this cohort highlight epigenetic mechanisms underlying the pathogenesis of EOCRC and nominate novel biomarkers for EOCRC in underrepresented populations.

Smads and their transcription factor partners mediate the transcriptional responses of target cells to secreted ligands of the Transforming Growth Factor-β (TGF-β) family, including those of the conserved bone morphogenetic protein (BMP) family, yet only a small number of direct target genes have been well characterized. In C. elegans, the BMP2/4 ortholog DBL-1 regulates multiple biological functions, including body size, via a canonical receptor-Smad signaling cascade. Here, we identify functional binding sites for SMA-3/Smad and its transcriptional partner SMA-9/Schnurri based on ChIP-seq peaks (identified by modEncode) and expression differences of nearby genes identified from RNA-seq analysis of corresponding mutants. We found that SMA-3 and SMA-9 have both overlapping and unique target genes. At a genome-wide scale, SMA-3/Smad acts as a transcriptional activator, whereas SMA-9/Schnurri direct targets include both activated and repressed genes. Mutations in sma-9 partially suppress the small body size phenotype of sma-3, suggesting some level of antagonism between these factors and challenging the prevailing model for Schnurri function. Functional analysis of target genes revealed a novel role in body size for genes involved in one-carbon metabolism and in the endoplasmic reticulum (ER) secretory pathway, including the disulfide reductase dpy-11. Our findings indicate that Smads and SMA-9/Schnurri have previously unappreciated complex genetic and genomic regulatory interactions that in turn regulate the secretion of extracellular components like collagen into the cuticle to mediate body size regulation.

Cross talk between tumor cells and immune cells enables tumor cells to escape immune surveillance and dictate responses to immunotherapy. Previous studies have identified that downregulation of the glycolytic enzyme fructose-1,6-bisphosphate aldolase B (ALDOB) in tumor cells orchestrated metabolic programming to favor HCC. However, it remains elusive whether and how ALDOB expression in tumor cells affects the tumor microenvironment in HCC.

We found that ALDOB downregulation was negatively correlated with CD8 + T cell infiltration in human HCC tumor tissues but in a state of exhaustion. Similar observations were made in mice with liver-specific ALDOB knockout or in subcutaneous tumor models with ALDOB knockdown. Moreover, ALDOB deficiency in tumor cells upregulates TGF-β expression, thereby increasing the number of Treg cells and impairing the activity of CD8 + T cells. Consistently, a combination of low ALDOB and high TGF-β expression exhibited the worst overall survival for patients with HCC. More importantly, the simultaneous blocking of TGF-β and programmed cell death (PD) 1 with antibodies additively inhibited tumorigenesis induced by ALDOB deficiency in mice. Further mechanistic experiments demonstrated that ALDOB enters the nucleus and interacts with lysine acetyltransferase 2A, leading to inhibition of H3K9 acetylation and thereby suppressing TGFB1 transcription. Consistently, inhibition of lysine acetyltransferase 2A activity by small molecule inhibitors suppressed TGF-β and HCC.

Our study has revealed a novel mechanism by which a metabolic enzyme in tumor cells epigenetically modulates TGF-β signaling, thereby enabling cancer cells to evade immune surveillance and affect their response to immunotherapy.

Bone homeostasis relies on several contributing factors, encompassing growth factors and mechanical stimuli. While bone morphogenetic protein (BMP) signaling is acknowledged for its essential role in skeletal development, its specific impact on mandibular morphogenesis remains unexplored. Here, we investigated the involvement of BMP signaling and mechanical loading through mastication in postnatal mandibular morphogenesis.

We employed conditional deletion of Bmpr1a in osteoblasts and chondrocytes via Osterix-Cre. Cre activity was induced at birth for the 3-week group and at three weeks for the 9-week and 12-week groups, respectively. The conditional knockout (cKO) and control mice were given either a regular diet (hard diet, HD) or a powdered diet (soft diet, SD) from 3 weeks until sample collection, followed by micro-CT and histological analysis.

The cKO mice exhibited shorter anterior lengths and a posteriorly inclined ramus across all age groups compared to the control mice. The cKO mice displayed an enlarged hypertrophic cartilage area along with fewer osteoclast numbers in the subchondral bone of the condyle compared to the control group at three weeks, followed by a reduction in the cartilage area in the posterior region at twelve weeks. Superimposed imaging and histomorphometrical analysis of the condyle revealed that BMP signaling primarily affects the posterior part of the condyle, while mastication affects the anterior part.

Using 3D landmark-based geometric morphometrics and histological assessments of the mandible, we demonstrated that BMP signaling and mechanical loading reciprocally contribute to the morphological alterations of the mandible and condyle during postnatal development.

Human papillomavirus (HPV) is involved in virtually all cases of cervical cancer. However, HPV alone is not sufficient to cause malignant development. The effects of chronic inflammation and the interaction of immune components with the microenvironment infected with the high-risk HPV type (HR) may contribute to cancer development. Transforming growth factor β (TGFB) appears to play an important role in cervical carcinogenesis. Protein and mRNA levels of this cytokine gradually increase as normal tissue develops into malignant tissue and are closely related to the severity of HPV infection. At the onset of infection, TGFB can inhibit the proliferation of infected cells and viral amplification by inhibiting cell growth and downregulating the transcriptional activity of the long control region (LCR) of HPV, thereby reducing the expression of early genes. When infected cells progress to a malignant phenotype, the response to the cell growth inhibitory effect of TGFB1 is lost and the suppression of E6 and E7 expression decreases. Subsequently, TGFB1 expression is upregulated by high levels of E6 and E7 oncoproteins, leading to an increase in TGFB1 in the tumor microenvironment, where this molecule promotes epithelial-to-mesenchymal transition (EMT), cell motility, angiogenesis, and immunosuppression. This interaction between HPV oncoproteins and TGFB1 is an important mechanism promoting the development and progression of cervical cancer.

Activin receptor type 1 (ACVR1; ALK2) and activin receptor like type 1 (ACVRL1; ALK1) are transforming growth factor beta family receptors that integrate extracellular signals of bone morphogenic proteins (BMPs) and activins into Mothers Against Decapentaplegic homolog 1/5 (SMAD1/SMAD5) signaling complexes. Several activating mutations in ALK2 are implicated in fibrodysplasia ossificans progressiva (FOP), diffuse intrinsic pontine gliomas, and ependymomas. The ALK2 R206H mutation is also present in a subset of endometrial tumors, melanomas, non-small lung cancers, and colorectal cancers, and ALK2 expression is elevated in pancreatic cancer. Using DNA-encoded chemistry technology, we screened 3.94 billion unique compounds from our diverse DNA-encoded chemical libraries (DECLs) against the kinase domain of ALK2. Off-DNA synthesis of DECL hits and biochemical validation revealed nanomolar potent ALK2 inhibitors. Further structure-activity relationship studies yielded center for drug discovery (CDD)-2789, a potent [NanoBRET (NB) cell IC50: 0.54 μM] and metabolically stable analog with good pharmacological profile. Crystal structures of ALK2 bound with CDD-2281, CDD-2282, or CDD-2789 show that these inhibitors bind the active site through Van der Waals interactions and solvent-mediated hydrogen bonds. CDD-2789 exhibits high selectivity toward ALK2/ALK1 in KINOMEscan analysis and NB K192 assay. In cell-based studies, ALK2 inhibitors effectively attenuated activin A and BMP-induced Phosphorylated SMAD1/5 activation in fibroblasts from individuals with FOP in a dose-dependent manner. Thus, CDD-2789 is a valuable tool compound for further investigation of the biological functions of ALK2 and ALK1 and the therapeutic potential of specific inhibition of ALK2.

Idiopathic pulmonary fibrosis (IPF) is a prevalent chronic pulmonary fibrosis disease characterized by alveolar epithelial cell damage, fibroblast proliferation and activation, excessive extracellular matrix deposition, and abnormal epithelial-mesenchymal transition (EMT), resulting in tissue remodeling and irreversible structural distortion. The mortality rate of IPF is very high, with a median survival time of 2-3 years after diagnosis. The exact cause of IPF remains unknown, but increasing evidence supports the central role of epigenetic changes, particularly microRNA (miRNA), in IPF. Approximately 10% of miRNAs in IPF lung tissue exhibit differential expression compared to normal lung tissue. Diverse miRNA phenotypes exert either a pro-fibrotic or anti-fibrotic influence on the progression of IPF. In the context of IPF, epigenetic factors such as DNA methylation and long non-coding RNAs (lncRNAs) regulate differentially expressed miRNAs, which in turn modulate various signaling pathways implicated in this process, including transforming growth factor-β1 (TGF-β1)/Smad, mitogen-activated protein kinase (MAPK), and phosphatidylinositol-3-kinase/protein kinase B (PI3K/AKT) pathways. Therefore, this review presents the epidemiology of IPF, discusses the multifaceted regulatory roles of miRNAs in IPF, and explores the impact of miRNAs on IPF through various pathways, particularly the TGF-β1/Smad pathway and its constituent structures. Consequently, we investigate the potential for targeting miRNAs as a treatment for IPF, thereby contributing to advancements in IPF research.

Soluble transforming growth factor beta receptor 3 (sTGFBR3) antagonist is a new focus in the research and development of Alzheimer's disease (AD) drugs. Our previous studies have identified sTGFBR3 as a promising new target for AD, with few targeted antagonists identified. In this study, we performed structural modeling of sTGFBR3 using AlphaFold2, followed by high-throughput virtual screening and surface plasmon resonance assays. which collectively identified Xanthone as potential compounds for targeting sTGFBR3. After optimizing the sTGFBR3-Xanthone complex using molecular dynamics (MD) simulations, we prepared a series of novel Xanthone derivatives and evaluated their anti-inflammatory activity, toxicity, and structure-activity relationship in BV2 cell model induced by lipopolysaccharides (LPS) or APP/PS1/tau mouse brain extract (BE). Several derivatives with the most potent anti-inflammatory activity were tested for blood-brain barrier permeability and sTGFBR3 affinity. Derivative P24, selected for its superior properties, was further evaluated in vitro. The results indicated that P24 increased the activation of TGF-β signaling and decreased the activation of IκBα/NF-κB signaling by targeting sTGFBR3, thereby regulating the inflammation-phagocytosis balance in microglia. Moreover, the low acute toxicity, long half-life, and low plasma clearance of P24 suggest that it can be sustained in vivo. This property may render P24 a more effective treatment modality for chronic diseases, particularly AD. The study demonstrates P24 serve as potential novel candidates for the treatment of AD via antagonizing sTGFBR3.

The TGF-β signaling pathway plays an important role in wound healing and immune response. In this study, a TGF-β type I receptor (TGF-βRI) homolog was cloned and characterized from freshwater mussel Hyriopsis cumingii. The full-length cDNA of the TGF-β RI gene was 2017 bp, with a 1554 bp open reading frame (ORF), and encoded 517 amino acids. The predictive analysis further identified distinct regions within the TGF-βRI protein: a signal peptide, a membrane outer region, a transmembrane region, and an intracellular region. Real-time quantitative PCR results showed that the TGF-β RI gene was expressed in all tissues of healthy mussels. The transcripts of TGF-β RI in hemocytes and hepatopancreas were significantly up-regulated at different periods after stimulation with Aeromonas hydrophila and peptidoglycan (PGN) (P < 0.05). The mRNA expression of TGF-β RI progressively increased from day 1 to day 10 after trauma (P < 0.05), and it returned to the initial level by day 15. The expression levels of TGF-β , Smad5, MMP1/19, and TIMP1/2, but not Smad3/4, were significantly up-regulated at different time points after trauma. However, the expression levels of TGF-β , MMP1/19, and TIMP2 were decreased after treatment with the inhibitor SB431542. Furthermore, the recombinant TGF-βRI proteins were expressed in vitro and existed in the form of inclusion bodies. Western blotting results showed that TGF-βRI proteins were expressed constitutively in various tissues of mussels, and their expression was up-regulated after trauma, which was consistent with the mRNA expression trend. These results indicate that TGF-β RI is involved in the process of wound repair and immune response.

Untreated primary carcinomas often lead to progression, invasion and metastasis, a process that involves the epithelial-to-mesenchymal transition (EMT). Several transcription factors (TFs) mediate the development of EMT, including SNAIL1/SNAIL2, TWIST1/TWIST2 and ZEB1/ZEB2, which are overexpressed in various carcinomas along with the under expression of the metastasis suppressor Raf Kinase Inhibitor Protein (RKIP). Overexpression of RKIP inhibits EMT and the above associated TFs. We, therefore, hypothesized that there are inhibitory cross-talk signaling pathways between RKIP and these TFs. Accordingly, we analyzed the various properties and biomarkers associated with the epithelial and mesenchymal tissues and the various molecular signaling pathways that trigger the EMT phenotype such as the TGF-β, the RTK and the Wnt pathways. We also presented the various functions and the transcriptional, post-transcriptional and epigenetic regulations for the expression of each of the EMT TFs. Likewise, we describe the transcriptional, post-transcriptional and epigenetic regulations of RKIP expression. Various signaling pathways mediated by RKIP, including the Raf/MEK/ERK pathway, inhibit the TFs associated with EMT and the stabilization of epithelial E-Cadherin expression. The inverse relationship between RKIP and the TF expressions and the cross-talks were further analyzed by bioinformatic analysis. High mRNA levels of RKIP correlated negatively with those of SNAIL1, SNAIL2, TWIST1, TWIST2, ZEB1, and ZEB2 in several but not all carcinomas. However, in these carcinomas, high levels of RKIP were associated with good prognosis, whereas high levels of the above transcription factors were associated with poor prognosis. Based on the inverse relationship between RKIP and EMT TFs, it is postulated that the expression level of RKIP in various carcinomas is clinically relevant as both a prognostic and diagnostic biomarker. In addition, targeting RKIP induction by agonists, gene therapy and immunotherapy will result not only in the inhibition of EMT and metastases in carcinomas, but also in the inhibition of tumor growth and reversal of resistance to various therapeutic strategies. However, such targeting strategies must be better investigated as a result of tumor heterogeneities and inherent resistance and should be better adapted as personalized medicine.

Breast cancer has surpassed lung cancer as the most prevalent malignancy affecting women worldwide. Triple-negative breast cancer (TNBC) is the type of breast cancer with the worst prognosis. As a heterogeneous disease, TNBC has a pathogenesis that involves multiple oncogenic pathways, including involvement of gene mutations and alterations in signaling pathways. MicroRNAs (miRNAs) are small endogenous, single-stranded non-coding RNAs that bind to the 3' untranslated region of target cell mRNAs to negatively regulate the gene expression of these specific mRNAs. Therefore, miRNAs are involved in cell growth, development, division and differentiation stages. miRNAs are also involved in gene targeting in tumorigenesis, tumor growth and the regulation of metastasis, including in breast cancer. Meanwhile, miRNAs also regulate components of signaling pathways. In this review, the role of miRNAs in the TNBC signaling pathway discovered in recent years is described in detail. The new concept of bi-targeted therapy for breast cancer using miRNA and artificial intelligence is also discussed.

Transforming growth factor β (TGF-β) is a ubiquitous molecule that is extremely conserved structurally and plays a systemic role in human organism. TGF-β is a homodimeric molecule consisting of two subunits joined through a disulphide bond. In mammals, three genes code for TGF-β1, TGF-β2, and TGF-β3 isoforms of this cytokine with a dominating expression of TGF-β1. Virtually, all normal cells contain TGF-β and its specific receptors. Considering the exceptional role of fine balance played by the TGF-β in anumber of physiological and pathological processes in human body, this cytokine may be proposed for use in medicine as an immunosuppressant in transplantology, wound healing and bone repair. TGFb itself is an important target in oncology. Strategies for blocking members of TGF-β signaling pathway as therapeutic targets have been considered. In this review, signalling mechanisms of TGF-β1 action are addressed, and their role in physiology and pathology with main focus on carcinogenesis are described.

Lung fibroblasts play a central role in maintaining lung homeostasis and facilitating repair through the synthesis and organization of the extracellular matrix (ECM). This study investigated the cross-talk between interleukin-1 alpha (IL-1α) and transforming growth factor-β (TGF-β) signaling, two key regulators in tissue repair and fibrosis, in the context of lung fibroblast repair in the healthy lung.

Stimulation of lung fibroblasts with TGF-β1 and TGF-β2 induced collagen-I and fibronectin protein expression (p < 0.05), a response inhibited with co-treatment with IL-1α (p < 0.05). Additionally, TGF-β1 and TGF-β2 induced myofibroblast differentiation, and collagen-I gel contraction, which were both suppressed by IL-1α (p < 0.05). In contrast, interleukin (IL)-6, IL-8 and thymic stromal lymphopoietin induced by IL-1α, were unaffected by TGF-β1 or TGF-β2. Mechanistically, IL-1α administration led to the suppression of TGF-β1 and TGF-β2 signaling, through downregulation of mRNA and protein for TGF-β receptor II and the downstream adaptor protein TRAF6, but not through miR-146a that is known to be induced by IL-1α.

IL-1α acts as a master regulator, modulating TGF-β1 and TGF-β2-induced ECM production, remodeling, and myofibroblast differentiation in human lung fibroblasts, playing a vital role in balancing tissue repair versus fibrosis. Further research is required to understand the dysregulated cross-talk between IL-1α and TGF-β signaling in chronic lung diseases and the exploration of therapeutic opportunities.

Primary human lung fibroblasts (PHLF) were treated with media control, or 1 ng/ml IL-1α with or without 50 ng/ml TGF-β1 or TGF-β2 for 1, 6 and 72 h. Cell lysates were assessed for the expression of ECM proteins and signaling molecules by western blot, miRNA by qPCR, mRNA by RNA sequencing and cell supernatants for cytokine production by ELISA. PHLFs were also seeded in non-tethered collagen-I gels to measure contraction, and myofibroblast differentiation using confocal microscopy.

The regeneration of tendon-bone interface tissue has become a topic of great interest in recent years. However, the complex nature of this interface has posed challenges in finding suitable solutions. Tissue engineering, with its potential to improve clinical outcomes and play a crucial role in musculoskeletal function, has been increasingly explored for tendon-bone interface regeneration. This review focuses on the research advancements of electrospinning technology in interface tissue engineering. By utilizing electrospinning, researchers have been able to fabricate scaffolds with tailored properties to promote the regeneration and integration of tendon and bone tissues. The review discusses the unique structure and function of the tendon-bone interface, the mechanisms involved in its healing, and the limitations currently faced in achieving successful regeneration. Additionally, it highlights the potential of electrospinning technology in scaffold fabrication and its role in facilitating the development of functional and integrated tendon-bone interface tissues. Overall, this review provides valuable insights into the application of electrospinning technology for tendon-bone interface tissue engineering, emphasizing its significance in addressing the challenges associated with regeneration in this complex interface.

Focal segmental glomerulosclerosis (FSGS), a clinicopathological condition characterized by nephrotic-range proteinuria, has a high risk of progression to end-stage renal disease (ESRD). Meanwhile, the recurrence of FSGS after renal transplantation is one of the main causes of graft loss. The diagnosis of recurrent FSGS is mainly based on renal puncture biopsy transplants, an approach not widely consented by patients with early mild disease. Therefore, there is an urgent need to find definitive diagnostic markers that can act as a target for early diagnosis and intervention in the treatment of patients. In this review, we summarize the domestic and international studies on the pathophysiology, pathogenesis and earliest screening methods of FSGS and describe the functions and roles of specific circulating factors in the progression of early FSGS, in order to provide a new theoretical basis for early diagnosis of FSGS recurrence, as well as aid the exploration of therapeutic targets.

Metastatic melanoma, a deadly form of skin cancer, often develops resistance to the BRAF inhibitor drug vemurafenib, highlighting the need for understanding the underlying mechanisms of resistance and exploring potential therapeutic strategies targeting integrins and TGF-β signalling. In this study, the role of integrins and TGF-β signalling in vemurafenib resistance in melanoma was investigated, and the potential of combining vemurafenib with cilengitide as a therapeutic strategy was investigated. In this study, it was found that the transcription of PAI1 and p21 was induced by acquired vemurafenib resistance, and ITGA5 levels were increased as a result of this resistance. The transcription of ITGA5 was mediated by the TGF-β pathway in the development of vemurafenib resistance. A synergistic effect on the proliferation of vemurafenib-resistant melanoma cells was observed with the combination therapy of vemurafenib and cilengitide. Additionally, this combination therapy significantly decreased invasion and colony formation in these resistant cells. In conclusion, it is suggested that targeting integrins and TGF-β signalling, specifically ITGA5, ITGB3, PAI1, and p21, may offer promising approaches to overcoming vemurafenib resistance, thereby improving outcomes for metastatic melanoma patients.

Pulmonary hypertension (PH) is a complex cardiopulmonary disorder impacting the lung vasculature, resulting in increased pulmonary vascular resistance that leads to right ventricular dysfunction. Pulmonary hypertension comprises of 5 groups (PH group 1 to 5) where group 1 pulmonary arterial hypertension (PAH), results from alterations that directly affect the pulmonary arteries. Although PAH has a complex pathophysiology that is not completely understood, it is known to be a multifactorial disease that results from a combination of genetic, epigenetic and environmental factors, leading to a varied range of symptoms in PAH patients. PAH does not have a cure, its incidence and prevalence continue to increase every year, resulting in higher morbidity and mortality rates. In this review, we discuss the different pathologic mechanisms with a focus on epigenetic modifications and their roles in the development and progression of PAH. These modifications include DNA methylation, histone modifications, and microRNA dysregulation. Understanding these epigenetic modifications will improve our understanding of PAH and unveil novel therapeutic targets, thus steering research toward innovative treatment strategies.

Cardiac fibrosis is a significant contributor to heart failure, a condition that continues to affect a growing number of patients worldwide. Various cardiovascular comorbidities can exacerbate cardiac fibrosis. While fibroblasts are believed to be the primary cell type underlying fibrosis, recent and emerging data suggest that other cell types can also potentiate or expedite fibrotic processes. Over the past few decades, clinicians have developed therapeutics that can blunt the development and progression of cardiac fibrosis. While these strategies have yielded positive results, overall clinical outcomes for patients suffering from heart failure continue to be dire. Herein, we overview the molecular and cellular mechanisms underlying cardiac tissue fibrosis. To do so, we establish the known mechanisms that drive fibrosis in the heart, outline the diagnostic tools available, and summarize the treatment options used in contemporary clinical practice. Finally, we underscore the critical role the immune microenvironment plays in the pathogenesis of cardiac fibrosis.

Transforming growth factor-β (TGF-β) signaling is initiated by activation of transmembrane TGF-β receptors (TGFBR), which deploys Smad2/3 transcription factors to control cellular responses. Failure or dysregulation in the TGF-β signaling pathways leads to pathological conditions. TGF-β signaling is regulated at different levels along the pathways and begins with the liberation of TGF-β ligand from its latent form. The mechanisms of TGFBR activation display selectivity to cell types, agonists, and TGF-β isoforms, enabling precise control of TGF-β signals. In addition, the cell surface compartments used to release active TGF-β are surprisingly vibrant, using thrombospondins, integrins, matrix metalloproteinases and reactive oxygen species. The scope of TGFBR activation is further unfolded with the discovery of TGFBR activation initiated by other signaling pathways. The unique combination of mechanisms works in series to trigger TGFBR activation, which can be explored as therapeutic targets. This comprehensive review provides valuable insights into the diverse mechanisms underpinning TGFBR activation, shedding light on potential avenues for therapeutic exploration.

Twisted gastrulation (TWSG1) is an evolutionarily conserved secreted glycoprotein which controls signaling by Bone Morphogenetic Proteins (BMPs). TWSG1 binds BMPs and their antagonist Chordin to control BMP signaling during embryonic development, kidney regeneration and cancer. We report crystal structures of TWSG1 alone and in complex with a BMP ligand, Growth Differentiation Factor 5. TWSG1 is composed of two distinct, disulfide-rich domains. The TWSG1 N-terminal domain occupies the BMP type 1 receptor binding site on BMPs, whereas the C-terminal domain binds to a Chordin family member. We show that TWSG1 inhibits BMP function in cellular signaling assays and mouse colon organoids. This inhibitory function is abolished in a TWSG1 mutant that cannot bind BMPs. The same mutation in the Drosophila TWSG1 ortholog Tsg fails to mediate BMP gradient formation required for dorsal-ventral axis patterning of the early embryo. Our studies reveal the evolutionarily conserved mechanism of BMP signaling inhibition by TWSG1.

Aim of the study: Activating Transforming factor 3 (ATF3) is a stress induced gene and closely associated with neuro-inflammation while Transforming growth Factor Beta (TGFβ) signalling is also reported to be involved in neuro-inflammation and hyper-excitability associated with drug resistant epilepsy. Animal model studies indicate the involvement of ATF3 and TGFβ receptors to promote epileptogenesis. Human studies also show that TGFβ signalling is activated in MTLE-HS. However, lack of studies on ATF3 and TGFβRI expression in MTLE-HS patients exists. We hypothesize that ATF3 and TGFβRI might be expressed in hippocampi of patients with MTLE-HS and playing role in epileptogenesis. Materials & methods: Protein expression of ATF3 and TGFβRI was performed by western blotting. Localisation of ATF3 was performed by immunohistochemistry and immunoflorescence. Results: Protein expression of ATF3 and TGFβRI was significantly up-regulated in hippocampi of patients as compared to controls. Also ATF3 IR was significantly expressed in hippocampi of patients and ATF3 was expressed predominantly in cytoplasm as compared to nucleus. No correlation was found between ATF3 expression and epilepsy duration and seizure frequency. Conclusions: ATF3 and TGFβRI are both important players in neuro-inflammation and might potentiate epileptogenesis in these patients.

The Transforming Growth Factor beta (TGF-β) family consists of numerous secreted peptide growth factors that play significant roles in cell function, tissue patterning, and organismal homeostasis, including wound repair and immunity. Typically studied as homodimers, these ligands have the potential to diversify their functions through ligand interactions that may enhance, repress, or generate novel functions. In the nematode Caenorhabditis elegans, there are only five TGF-β ligands, providing an opportunity to dissect ligand interactions in fewer combinations than in vertebrates. As in vertebrates, these ligands can be divided into bone morphogenetic protein (BMP) and TGF-β/Activin subfamilies that predominantly signal through discrete signaling pathways. The BMP subfamily ligand DBL-1 has been well studied for its role in the innate immune response in C. elegans. Here we show that all five TGF-β ligands play a role in survival on bacterial pathogens. We also demonstrate that multiple TGF-β ligand pairs act nonredundantly as part of this response. We show that the two BMP-like ligands-DBL-1 and TIG-2-function independently of each other in the immune response, while TIG-2/BMP and the TGF-β/Activin-like ligand TIG-3 function together. Structural modeling supports the potential for TIG-2 and TIG-3 to form heterodimers. Additionally, we identify TIG-2 and TIG-3 as members of a rare subset of TGF-β ligands lacking the conserved cysteine responsible for disulfide linking mature dimers. Finally, we show that canonical DBL-1/BMP receptor and Smad signal transducers function in the response to bacterial pathogens, while components of the DAF-7 TGF-β/Activin signaling pathway do not play a major role in survival. These results demonstrate a novel potential for BMP and TGF-β/Activin subfamily ligands to interact and may provide a mechanism for distinguishing the developmental and homeostatic functions of these ligands from an acute response such as the innate immune response to bacterial pathogens.

Mesenchymal stem cells (MSCs) are multipotent cells that can differentiate into cells of different lineages to form mesenchymal tissues, which are promising in regard to treatment for bone diseases. Their osteogenic differentiation is under the tight regulation of intrinsic and extrinsic factors. Transforming growth factor β (TGF-β) is an essential growth factor in bone metabolism, which regulates the differentiation of MSCs. However, published studies differ in their views on whether TGF-β signaling regulates the osteogenic differentiation of MSCs positively or negatively. The controversial results have not been summarized systematically and the related explanations are required. Therefore, we reviewed the basics of TGF-β signaling and summarized how each of three isoforms regulates osteogenic differentiation. Three isoforms of TGF-β (TGF-β1/β2/β3) play distinct roles in regulating osteogenic differentiation of MSCs. Additionally, other possible sources of conflicts are summarized here. Further understanding of TGF-β signaling regulation in MSCs may lead to new applications to promote bone regeneration and improve therapies for bone diseases.

Breast cancer is one of the prevailing cancers globally, with a high mortality rate. Metastatic breast cancer (MBC) is an advanced stage of cancer, characterised by a highly nonlinear, heterogeneous process involving numerous singling pathways and regulatory interactions. Epithelial-mesenchymal transition (EMT) emerges as a key mechanism exploited by cancer cells. Transforming Growth Factor-β (TGFβ)-dependent signalling is attributed to promote EMT in advanced stages of breast cancer. A comprehensive regulatory map of TGFβ induced EMT was developed through an extensive literature survey. The network assembled comprises of 312 distinct species (proteins, genes, RNAs, complexes), and 426 reactions (state transitions, nuclear translocations, complex associations, and dissociations). The map was developed by following Systems Biology Graphical Notation (SBGN) using Cell Designer and made publicly available using MINERVA ( http://35.174.227.105:8080/minerva/?id=Metastatic_Breast_Cancer_1 ). While the complete molecular mechanism of MBC is still not known, the map captures the elaborate signalling interplay of TGFβ induced EMT-promoting MBC. Subsequently, the disease map assembled was translated into a Boolean model utilising CaSQ and analysed using Cell Collective. Simulations of these have captured the known experimental outcomes of TGFβ induced EMT in MBC. Hub regulators of the assembled map were identified, and their transcriptome-based analysis confirmed their role in cancer metastasis. Elaborate analysis of this map may help in gaining additional insights into the development and progression of metastatic breast cancer.

Salivary gland damage and hypofunction result from various disorders, including autoimmune Sjögren's disease (SjD) and IgG4-related disease (IgG4-RD), as well as a side effect of radiotherapy for treating head and neck cancers. There are no therapeutic strategies to prevent the loss of salivary gland function in these disorders nor facilitate functional salivary gland regeneration. However, ongoing aquaporin-1 gene therapy trials to restore saliva flow show promise. To identify and develop novel therapeutic targets, we must better understand the cell-specific signaling processes involved in salivary gland regeneration. Transforming growth factor-β (TGF-β) signaling is essential to tissue fibrosis, a major endpoint in salivary gland degeneration, which develops in the salivary glands of patients with SjD, IgG4-RD, and radiation-induced damage. Though the deposition and remodeling of extracellular matrix proteins are essential to repair salivary gland damage, pathological fibrosis results in tissue hardening and chronic salivary gland dysfunction orchestrated by multiple cell types, including fibroblasts, myofibroblasts, endothelial cells, stromal cells, and lymphocytes, macrophages, and other immune cell populations. This review is focused on the role of TGF-β signaling in the development of salivary gland fibrosis and the potential for targeting TGF-β as a novel therapeutic approach to regenerate functional salivary glands. The studies presented highlight the divergent roles of TGF-β signaling in salivary gland development and dysfunction and illuminate specific cell populations in damaged or diseased salivary glands that mediate the effects of TGF-β. Overall, these studies strongly support the premise that blocking TGF-β signaling holds promise for the regeneration of functional salivary glands.

The TGF-β family is a group of 25 kDa secretory cytokines, in mammals consisting of three dimeric isoforms (TGF-βs 1, 2, and 3), each encoded on a separate gene with unique regulatory elements. Each isoform plays unique, diverse, and pivotal roles in cell growth, survival, immune response, and differentiation. However, many researchers in the TGF-β field often mistakenly assume a uniform functionality among all three isoforms. Although TGF-βs are essential for normal development and many cellular and physiological processes, their dysregulated expression contributes significantly to various diseases. Notably, they drive conditions like fibrosis and tumor metastasis/progression. To counter these pathologies, extensive efforts have been directed towards targeting TGF-βs, resulting in the development of a range of TGF-β inhibitors. Despite some clinical success, these agents have yet to reach their full potential in the treatment of cancers. A significant challenge rests in effectively targeting TGF-βs' pathological functions while preserving their physiological roles. Many existing approaches collectively target all three isoforms, failing to target just the specific deregulated ones. Additionally, most strategies tackle the entire TGF-β signaling pathway instead of focusing on disease-specific components or preferentially targeting tumors. This review gives a unique historical overview of the TGF-β field often missed in other reviews and provides a current landscape of TGF-β research, emphasizing isoform-specific functions and disease implications. The review then delves into ongoing therapeutic strategies in cancer, stressing the need for more tools that target specific isoforms and disease-related pathway components, advocating mechanism-based and refined approaches to enhance the effectiveness of TGF-β-targeted cancer therapies.

The transforming growth factor beta (TGF-β) signaling pathway is believed to play essential roles in several physiological activities, including cancer. TGF-β receptor type I (TBR-I) is a key membrane receptor protein in the TGF-β signaling pathway, which relates to many intracellular biological effects. In recent years, cold atmospheric plasma (CAP) has been found to have promising prospects in selective anticancer therapy and has confirmed its essential role in the TGF-β signaling pathway. However, the ambiguous effect of CAP-induced electric field (EF) on TBR-I still limits the application of CAP in clinical therapy. Molecular dynamics is applied to assess the effect of EF on the structure of the extracellular domain of TBR-I using a series of indicators and methods, and then we discuss the ligand binding ability of TBR-I. Results show that moderate EF intensities' structural restraints may contribute to the structural stability and ligand-binding ability of TBR-I, but an EF higher than 0.1 V/nm will be harmful. What's more, EF induces a change in the docking interface of TBR-I, showing the conformation and position of special sequences of residues decide the ligand binding surface. The relevant results suggest that CAP-induced EF plays a crucial role in receptor-receptor interaction and provides significant guidelines for EF-related anticancer therapy.

BMP9 and BMP10 are two major regulators of vascular homeostasis. These two ligands bind with high affinity to the endothelial type I kinase receptor ALK1, together with a type II receptor, leading to the direct phosphorylation of the SMAD transcription factors. Apart from this canonical pathway, little is known. Interestingly, mutations in this signaling pathway have been identified in two rare cardiovascular diseases, hereditary hemorrhagic telangiectasia and pulmonary arterial hypertension.

To get an overview of the signaling pathways modulated by BMP9 and BMP10 stimulation in endothelial cells, we employed an unbiased phosphoproteomic-based strategy. Identified phosphosites were validated by western blot analysis and regulated targets by RT-qPCR. Cell cycle analysis was analyzed by flow cytometry.

Large-scale phosphoproteomics revealed that BMP9 and BMP10 treatment induced a very similar phosphoproteomic profile. These BMPs activated a non-canonical transcriptional SMAD-dependent MAPK pathway (MEKK4/P38). We were able to validate this signaling pathway and demonstrated that this activation required the expression of the protein GADD45β. In turn, activated P38 phosphorylated the heat shock protein HSP27 and the endocytosis protein Eps15 (EGF receptor pathway substrate), and regulated the expression of specific genes (E-selectin, hyaluronan synthase 2 and cyclooxygenase 2). This study also highlighted the modulation in phosphorylation of proteins involved in transcriptional regulation (phosphorylation of the endothelial transcription factor ERG) and cell cycle inhibition (CDK4/6 pathway). Accordingly, we found that BMP10 induced a G1 cell cycle arrest and inhibited the mRNA expression of E2F2, cyclinD1 and cyclinA1.

Overall, our phosphoproteomic screen identified numerous proteins whose phosphorylation state is impacted by BMP9 and BMP10 treatment, paving the way for a better understanding of the molecular mechanisms regulated by BMP signaling in vascular diseases.

Retinal degeneration, characterized by Müller cell gliosis and photoreceptor apoptosis, is considered an early event in diabetic retinopathy (DR). Our previous study proposed that GMFB may mediate diabetic retinal degeneration. This study identified GMFB as a sensitive and functional gliosis marker for DR. Compared to the wild type (WT) group, Gmfb knockout (KO) significantly improved visual function, attenuated gliosis, reduced the apoptosis of neurons, and decreased the mRNA levels of tumor necrosis factor α (Tnf-α) and interleukin-1β (Il-1β) in diabetic retinas. Tgf-β3 was enriched by hub genes using RNA sequencing in primary WT and KO Müller cells. Gmfb KO significantly upregulated the transforming growth factor (TGF)-β3 protein level via the AKT pathway. The protective effect of TGF-β3 in the vitreous resulted in significantly improved visual function and decreased the number of apoptotic cells in the diabetic retina. The protection of Gmfb KO in primary Müller cells against high glucose (HG)-induced photoreceptor apoptosis was partially counteracted by TGF-β3 antibody and administration of TGFBR1/2 inhibitors. Nuclear receptor subfamily 3 group C member 1 (NR3C1) binds to the promoter region of Gmfb and regulates Gmfb mRNA at the transcriptional level. NR3C1 was increased in the retinas of early diabetic rats but decreased in the retinas of late diabetic rats. N'-[(1E)-(3-Methoxyphenyl)Methylene]-3-Methyl-1H-Pyrazole-5-Carbohydrazide (DS-5) was identified as an inhibitor of GMFB, having a protective role in DR. We demonstrated that GMFB/AKT/TGF-β3 mediated early diabetic retinal degeneration in diabetic rats. This study provides a novel therapeutic strategy for treating retinal degeneration in patients with DR.

Neuropilin-1 (NRP1) is a transmembrane glycoprotein expressed by several cell types including, neurons, endothelial cells (ECs), smooth muscle cells, cardiomyocytes and immune cells comprising macrophages, dendritic cells and T cell subsets. Since NRP1 discovery in 1987 as an adhesion molecule in the frog nervous system, more than 2300 publications on PubMed investigated the function of NRP1 in physiological and pathological contexts. NRP1 has been characterised as a coreceptor for class 3 semaphorins and several members of the vascular endothelial growth factor (VEGF) family. Because the VEGF family is the main regulator of blood and lymphatic vessel growth in addition to promoting neurogenesis, neuronal patterning, neuroprotection and glial growth, the role of NRP1 in these biological processes has been extensively investigated. It is now established that NRP1 promotes the physiological growth of new vessels from pre-existing ones in the process of angiogenesis. Furthermore, several studies have shown that NRP1 mediates signalling pathways regulating pathological vascular growth in ocular neovascular diseases and tumour development. Less defined are the roles of NRP1 in maintaining the function of the quiescent established vasculature in an adult organism. This review will focus on the opposite roles of NRP1 in regulating transforming growth factor β signalling pathways in different cell types, and on the emerging role of endothelial NRP1 as an atheroprotective, anti-inflammatory factor involved in the response of ECs to shear stress.