Search Results (413)

The proliferation and migration of pulmonary artery smooth muscle cells (PASMCs) are key pathological features of vascular remodeling during pulmonary hypertension. Platelet-derived growth factor (PDGF) signaling is a major contributor to these processes. Given the importance of microRNA (miRNA) regulation in the PDGF signaling pathway in PASMCs, we hypothesized that imatinib, a tyrosine kinase inhibitor, modulates the expression levels of miRNAs responsive to PDGF signaling to ameliorate the PDGF signaling-induced PASMC phenotype. In this study, we investigated the role of miR-335-5p in PDGF signaling-induced PASMC proliferation and migration, as well as the involvement of imatinib in the regulatory network of miR-335-5p. miR-335-5p was identified as a critical negative regulator of PDGF signaling. Functional assays revealed that miR-335-5p significantly inhibits PASMC proliferation and migration. Through target prediction and validation, Rho GTPase Activating Protein 18 (ARHGAP18) was identified as a novel direct target of miR-335-5p. In addition, ARHGAP18 was found to play an essential role in regulating PASMC proliferation and migration. Although miR-335-5p was downregulated upon PDGF-BB stimulation, its expression was restored by imatinib. These findings highlight the important role of the imatinib–miR-335-5p–ARHGAP18 axis as a potential therapeutic target for pathological vascular remodeling. Full article

RAC3 encodes a small Rho-family GTPase essential for cytoskeletal regulation and neurodevelopment, and de novo RAC3 variants typically act as gain-of-function alleles that cause severe neurodevelopmental disorders. In this study, we analyzed a fetus with multisystem congenital anomalies and identified a de novo RAC3 p.(T17R) variant by genome sequencing. To elucidate the pathogenicity of this variant, we combined in silico variant prioritization, structural and energetic modeling, and pathogenicity prediction with in vitro biochemical assays, including GDP/GTP exchange, GTP hydrolysis, effector pull-down, and luciferase reporter analyses in COS7 cells, as well as morphological analysis of primary hippocampal neurons. Furthermore, we performed in vivo analyses using a mouse in utero electroporation to assess cortical neuron migration, axon extension, and dendritic development. Our biochemical results suggest that RAC3-T17R exhibits markedly increased GDP/GTP exchange, with a preference for GDP binding, and undetectable GTP hydrolysis. The mutant displayed minimal binding to canonical RAC effectors (PAK1, MLK2, and N-WASP) and failed to activate SRF-, NFκB-, or AP1-dependent transcription. Neuronal overexpression of RAC3-T17R impaired axon formation in vitro, while in vivo expression delayed cortical neuron migration and axon extension and reduced dendritic arborization. Clinically, the fetus exhibited corpus callosum agenesis, microcephaly, organomegaly, and limb contractures. Collectively, these findings indicate that the RAC3 p.(T17R) variant may represent a signaling-deficient allele with pleiotropic, variant-specific mechanisms that disrupt corticogenesis and broader organogenesis. Our multi-tiered in silico–in vitro–in vivo approach demonstrates that noncanonical RAC3 variants can produce complex, multisystem developmental phenotypes beyond previously recognized RAC3-related neurodevelopmental disorders. Full article

Background: Lipoprotein(a) [Lp(a)]-induced inflammation contributes to coronary artery spasm (CAS) by the contraction of vascular smooth muscle cells. However, the interaction between Lp(a) and soluble CD36 (sCD36)/interleukin (IL)-6/RAS Homolog Family Member A (RhoA)-GTP signaling pathway has not been evaluated. Methods: We investigated the relevance of Lp(a)/CD36 signaling in CAS patient monocyte-derived macrophages (PMDMs) and a human coronary artery smooth muscle cell (HCASMC) line using expression profile correlation analyses, molecular docking, RNA sequencing, flow cytometry, immunoblotting, and quantitative reverse transcription polymerase chain reaction. Results: Plasma Lp(a) and sCD36 levels in 41 CAS patients were significantly higher (p = 0.001) and positively correlated (r² = 0.3145, p < 0.001), a trend not observed in 36 non-CAS controls. RNA sequencing indicated a significant co-overexpression of CD36 and RhoA in Lp(a)-treated CAS PMDMs and HCASMCs, of which the mRNA and protein expression of CD36 and RhoA were significantly enhanced (p < 0.001) dose-dependently. Lp(a) rather than LDL preferentially induced CD80+ PMDM (M1) polarization. In HCASMCs, the CD36 knockdown using either short hairpin RNA or natural biflavonoid amentoflavone suppressed Lp(a)-upregulated protein expression of CD36, RhoA-GTP, IL-6, tumor necrosis factor (TNF)-α, nuclear factor (NF)-κB, and CD80; however, overexpressed CD36 increased their levels. Lp(a) decreased and amentoflavone increased the epigenetic expression of CD36 inhibitors, miR-335-5p, and miR-448, respectively. Reciprocally, an miRNA inhibitor or mimic could magnify or diminish Lp(a)-induced CD36, TNF-α, NF-κB and IL-6 expressions in HCASMCs, respectively. Conclusions: Elevated Lp(a) levels upregulate the CD36-dependent TNF-α/NF-κB/IL-6/RhoA-GTP signaling pathway in CAS PMDMs and HCASMCs, indicating that Lp(a)/CD36 inflammatory signaling, HCASMC activation, and macrophage M1 polarization mediate CAS development. Full article

RHOA, a member of the Rho family of small GTPases, harbors recurrent mutations in diverse cancers, but how these mutations cause their cellular effects remains poorly understood. To investigate their cellular consequences, we expressed oncogenic RHOA variants (R5Q, G17V, C16R, and A161P) in Saccharomyces cerevisiae, substituting for the essential yeast homologue RHO1. While the E40Q variant failed to complement RHO1 deletion, other mutants supported viability and enabled phenotypic characterization. All four variants conferred myriocin resistance, suggesting activation of the membrane stress response pathway, but induced no major changes in growth or caspofungin sensitivity. Using high-dimensional image analysis, we quantified 501 morphological parameters and applied principal component analysis and linear discriminant analysis to determine distinct phenotypic profiles. Gain-of-function (C16R and A161P) and loss-of-function (R5Q and G17V) mutants formed separate morphological clusters, indicating functional divergence. Our yeast model enabled systematic dissection of the functions of RHOA mutants and highlighted the utility of morphology-based approaches to characterize context-dependent mechanisms of oncogenesis. Full article

Background/Objectives: Mass-forming chronic pancreatitis (MFP) and pancreatic ductal adenocarcinoma (PDAC) can present with overlapping radiological, clinical, and serological features in patients with underlying chronic pancreatitis (CP), making differential diagnosis particularly challenging. Current diagnostic tools, including CA19-9 and endoscopic ultrasound (EUS) imaging, often lack the specificity needed to reliably distinguish between these conditions. The objective of this study was to investigate whether the proteomic profiling of endoscopic ultrasound-guided fine-needle aspiration (EUS-FNA) samples could provide molecular-level discrimination between MFP and PDAC in patients with CP. Methods: Thirty CP patients with solid pancreatic lesions were prospectively enrolled: 15 with histologically confirmed PDAC and 15 with MFP. Traditional diagnostic parameters, including CA19-9 levels and EUS characteristics, were recorded but found insufficient for differentiation. EUS-FNA samples were analyzed using label-free mass spectrometry. A total of 928 proteins were identified in PDAC samples and 555 in MFP samples. Differential abundance analysis and pathway enrichment were performed. Results: Overall, 88 proteins showed significant differential abundance between PDAC and MFP samples, of which 26 met stringent statistical thresholds. Among these, Carboxylesterase 2 (CES2), Carcinoembryonic Antigen-Related Cell Adhesion Molecule 1 (CEACAM1), Lumican (LUM), Transmembrane Protein 205 (TMEM205), and NAD(P)H Quinone Dehydrogenase 1 (NQO1) emerged as key discriminatory proteins. Pathway enrichment analysis revealed distinct biological processes between the groups, including mitochondrial fatty acid β-oxidation, Rho GTPase signaling, and platelet degranulation. Conclusions: Proteomic signatures derived from EUS-FNA samples offer a promising molecular approach to distinguish inflammatory pseudotumoral lesions from malignant pancreatic tumors in CP patients. This minimally invasive strategy could enhance diagnostic accuracy where current methods fall short. Further validation in larger, multicenter cohorts is warranted to confirm these findings and evaluate their clinical applicability. Full article

It has previously been reported that the RhoA/Rho-associated kinase (ROCK) pathway is involved in depolarization-induced contraction triggered by high [K⁺] stimulation in rat caudal arterial smooth muscle. Furthermore, we reported that activation of the upstream Ca²⁺-dependent proline-rich tyrosine kinase 2 (Pyk2) leads to phosphorylation of myosin targeting subunit of myosin light chain phosphatase (MYPT1) and 20 kDa myosin light chain (LC₂₀). These findings suggest that Rho guanine nucleotide exchange factors (RhoGEFs) or Rho GTPase-activating proteins (RhoGAPs) may mediate RhoA activation downstream of Pyk2, thereby contributing to depolarization-induced contraction. However, it remains unclear whether Pyk2 directly interacts with RhoGEFs or RhoGAPs. In this study, we investigated the interaction between Pyk2 and RhoGEFs or RhoGAPs during depolarization stimulation of rat caudal arterial smooth muscle. We examined the interaction between Pyk2 and RhoGEFs or RhoGAPs, which previously were identified in smooth muscle, specifically in rat caudal arterial smooth muscle, in response to 60 mM K⁺ stimulation by immunoprecipitation analysis. ArhGEF11, ArhGEF12, phosphorylated ArhGAP42 at Tyr792 (pTyr792-ArhGAP42) and phosphorylated ArhGAP42 at Tyr376 (pTyr376-ArhGAP42) co-immunoprecipitated with Pyk2. The co-immunoprecipitation of pTyr792-ArhGAP42, but not pTyr376-ArhGAP42, with Pyk2 was inhibited by a Pyk2 inhibitor, sodium salicylate. Furthermore, 60 mM K⁺ stimulation increased ArhGAP42 phosphorylation at Tyr792, which was also suppressed by sodium salicylate. These findings indicate that Pyk2-mediated phosphorylation of ArhGAP42 at Tyr792 may play a role in depolarization-induced contraction of rat caudal arterial smooth muscle. Full article

Small (monomeric) GTP-binding proteins (smgs; Cdc42 and Rac1) play requisite roles in islet beta cell function, including glucose-stimulated insulin secretion. In addition, emerging evidence suggests that sustained (constitutive) activation of smgs (e.g., Rac1) culminates in the genesis of islet beta cell dysfunction under the duress of chronic hyperglycemia. It is noteworthy that functions (i.e., activation–deactivation) of smgs in many cells, including the islet beta cell, have been shown to be under the regulatory control of at least three factors, namely the guanine nucleotide exchange factors (GEFs), the GTPase-activating proteins (GAPs), and the GDP-dissociation inhibitors (GDIs). The overall objective of this review is to highlight our current understanding of the regulatory roles of the RhoGDIβ-Rac1-CARD9 signalome in the pathology of beta cell dysfunction under chronic hyperglycemic stress. For brevity, this review is structured by an overview of smgs and their regulatory proteins/factors in the beta cell, followed by a discussion of potential roles of the RhoGDIβ-Rac1-CARD9 axis in the onset of cellular dysfunction under the duress of metabolic stress. Overall conclusions, potential knowledge gaps, and opportunities for future research in this field of islet biology are highlighted in the last section. Full article

Respiratory syncytial virus (RSV) is a major human respiratory pathogen, particularly affecting infants, the elderly, and immunocompromised individuals. RSV exists in both spherical and filamentous forms, with the filamentous morphology associated with enhanced infectivity and cell-to-cell spread. Here, we demonstrate that RhoA, a small GTPase involved in cytoskeletal regulation, is essential for filamentous RSV morphogenesis through its role in organizing lipid raft microdomains. Rhosin, a selective RhoA inhibitor developed through structure-guided screening, disrupts GEF–RhoA interactions to block RhoA activation. The pharmacological inhibition of RhoA with Rhosin significantly reduced filamentous virion formation, disrupted RSV fusion (F) protein colocalization with lipid rafts, and diminished cell-to-cell fusion, without affecting overall viral replication. Scanning electron microscopy revealed that Rhosin-treated infected HEp-2 cells exhibited fewer and shorter filamentous projections compared to the extensive filament formation seen in untreated cells. β-galactosidase-based fusion assays confirmed that reduced filamentation corresponded with decreased cell-to-cell fusion. The biophysical separation of RSV spherical and filamentous particles by sucrose gradient velocity sedimentation, coupled with fluorescence and transmission electron microscopy, showed that Rhosin treatment shifted virion morphology toward spherical forms. This suggests that RhoA activity is critical for filamentous virion assembly, which may enhance viral spread. Immunofluorescence microscopy using lipid raft-selective dyes (DiIC₁₆) and fusion protein-specific antibodies revealed the strong co-localization of RSV proteins with lipid rafts. Importantly, the pharmacological inhibition of RhoA with Rhosin disrupted F protein partitioning into raft domains, underscoring the requirement for intact lipid rafts in assembly. These findings highlight a novel role for host RhoA signaling in regulating viral assembly through raft microdomain organization, offering a potential target for host-directed antiviral intervention aimed at altering RSV structural phenotypes and limiting pathogenesis. Full article

Axon guidance, a fundamental process in neural circuit formation, is intricately regulated by Fibroblast Growth Factors (FGFs) and their receptors (FGFRs) through dynamic cytoskeletal remodeling. FGF signaling, mediated by heparan sulfate proteoglycans or Klotho co-factors, activates key downstream pathways: PI3K-Akt, JAK-STAT, PLCγ, and RAS-MAPK. These pathways orchestrate actin filament dynamics, microtubule stability, and the organization of intermediate filaments. These pathways converge on Rho GTPases, cofilin, profilin, and tau to balance the cytoskeletal assembly−disassembly cycles, enabling growth cone navigation. Unresolved questions, such as the mechanisms underlying FGF-mediated growth cone steering, highlight critical future research directions. This review integrates structural, molecular, and functional insights into how FGF-FGFR interactions regulate axon pathfinding, emphasizing the crosstalk between signaling cascades and cytoskeletal plasticity. Elucidating these mechanisms not only advances our understanding of neural development but also opens therapeutic avenues for neuro-developmental disorders, nerve injury, and neurodegenerative diseases by targeting FGF-driven cytoskeletal dynamics. Full article

The neurotrophic system includes neurotrophins, such as brain-derived neurotrophic factor (BDNF) and its precursor proBDNF, which play conflicting roles in neuronal survival and apoptosis, with their balance having a significant impact on neurodegenerative outcomes. While BDNF is widely acknowledged as a potent neurotrophin that promotes neuronal survival and differentiation, its precursor, proBDNF, has the opposite effect, promoting apoptosis and neuronal death. This review highlights the new and unique aspects of BDNF/proBDNF interaction in the modulation of neuronal apoptotic pathways in neurodegenerative disorders. It systematically discusses the cross-talk in apoptotic signaling at the molecular level, whereby BDNF activates survival pathways such as PI3K/Akt and MAPK/ERK, whereas proBDNF activates p75NTR and sortilin to induce neuronal apoptosis via JNK, RhoA, NFkB, and Rac-GTPase pathways such as caspase activation and mitochondrial injury. Moreover, this review emphasizes the factors that affect the balance between proBDNF and BDNF levels within the context of neurodegeneration, including proteolytic processing, the expression of TrkB and p75NTR receptors, and extrinsic gene transcription regulators. Cellular injury, stress, or signaling pathway alterations can disrupt the balance of BDNF/proBDNF, which may be involved in apoptotic-related neurodegenerative diseases like Alzheimer’s, Parkinson’s, and Huntington’s diseases. This review provides a comprehensive framework for targeting neurotrophin signaling in the development of innovative therapies for neuronal survival and managing apoptotic-related neurodegenerative disorders, addressing the mechanistic complexity and clinical feasibility of BDNF/proBDNF interaction. Full article

The Arhgap29 gene encodes Rho-GTPase-activating protein 29 (Arhgap29), which plays a crucial role in embryonic tissue development. Mutations in the Arhgap29 gene are significantly associated with non-syndromic cleft lip and palate (NSCL/P). Our study demonstrated that the deletion of Arhgap29 leads to syndromic cleft lip and palate (SCL/P) characteristics in mice, where, in addition to cleft palate, the mice exhibit craniofacial and systemic skeletal abnormalities. However, the mechanisms underlying these skeletal abnormalities remain unclear. Through micro-CT imaging, histological analysis, and transcriptomic methods, we discovered that the knockout of Arhgap29 delays the fusion of Meckel’s cartilage, widens cranial sutures, reduces bone quality, and alters the expression of osteoblasts and osteoclasts in the mandible. Digit defects, including ectrodactyly and impaired endochondral ossification, were also observed. Immunohistochemical analysis demonstrated the expression of Arhgap29 in both osteoblasts and osteoclasts, indicating its dual role in maintaining matrix homeostasis and regulating bone resorption equilibrium. Transcriptomic analysis revealed disrupted calcium and MAPK signaling pathways, while in vitro studies demonstrated impaired osteogenesis in Arhgap29-deficient calvarial cells, mirroring the in vivo defects. Furthermore, spatial transcriptomics linked the loss of Arhgap29 to defective bone differentiation and protein synthesis. Our findings underscore the critical role of Arhgap29 in the development of the mandible and digits, suggesting its potential as a pathogenic gene associated with syndromic cleft lip and palate (SCL/P). Full article

The aim of this work is to highlight the beneficial effects of bioactive peptides present in fermented whey (FW) and carotenoids from pumpkin (P) against the pro-oxidant effects of aflatoxin B1 and ochratoxin A at the neuronal level. For this purpose, SH-SY5Y human neuroblastoma differentiated cells were exposed to (A) mycotoxins, (B) the digesta of mycotoxin-contaminated bread formulated with P, or (C) bread enriched with FW + P. A proteomic approach using HPLC-MS/MS-QTOF was then employed to characterize the metabolic pathways affected by the presence of these components, as well as their ability to modulate the toxic effects exacerbated by mycotoxins. Gene ontology functional analysis revealed proteins primarily associated with nucleosome structure, such as the H3-H4 tetramer, H2A-H2B dimer, and HIRA, which were overexpressed in the presence of mycotoxins and, interestingly, downregulated with the addition of the functional ingredients. Additionally, important metabolic pathways associated with the RHO GTPase family, estrogen-dependent gene expression, and androgen receptor transcription stimulated by PKN1 activation were discovered. Network interaction analysis highlighted the modulation of cytoskeletal dynamics, cell migration, and stress responses. These findings provide novel insights into the neuroprotective potential of functional food components, supporting their use in mitigating mycotoxin-induced neuronal damage and opening new avenues for dietary-based neuroprotection strategies. Full article

Chronic liver diseases are marked by persistent inflammation and can evolve into liver fibrosis, cirrhosis, and hepatocellular carcinoma. In an affected liver, hepatic stellate cells (HSCs) transition from a quiescent to an activated state and adopt a myofibroblast-like cell phenotype. While these activated cells play a role in supporting liver regeneration, they can also have detrimental effects on liver function as the disease progresses to fibrosis and cirrhosis. These findings highlight the dynamic switching between different signaling pathways involving Ras, Rho GTPases, and Notch signaling. Notably, two specific members of the Ras and Rho GTPases, Eras and Rnd3, are predominantly expressed in quiescent HSCs, while Mras and Rhoc are more abundant in their activated forms. In addition, this study highlights the critical role of cytosolic Notch1 in quiescent HSCs and Rock in activated HSCs. We hypothesize that distinct yet interdependent intracellular signaling networks regulate HSC fate decisions in two key ways: by maintaining HSC quiescence and homeostasis and by facilitating HSC activation, thereby influencing processes such as proliferation, transdifferentiation, and mesenchymal transition. The proposed signaling model, combined with specific methodological tools for maintaining HSCs in a quiescent state, will deepen our understanding of the mechanisms underlying chronic liver disease and may also pave the way for innovative therapies. These therapies could include small molecule drugs targeting Ras- and Rho-dependent pathways. Full article

The p21-activated kinases (PAKs) are a group of evolutionarily conserved serine/threonine protein kinases and serve as a downstream target of the small GTPases Rac and Cdc42, both of which belong to the Rho family. PAKs play pivotal roles in various physiological processes, including cytoskeletal rearrangement and cellular signal transduction. Group II PAKs (PAK4-6) are particularly closely linked to human tumors, such as breast and pancreatic cancers, while Group I PAKs (PAK1-3) are indispensable for normal physiological functions such as cardiovascular development and neurogenesis. In recent years, the association of PAKs with diseases like cancer and the rise of small-molecule inhibitors targeting PAKs have attracted significant attention. This article focuses on the analysis of PAKs’ role in tumor progression and immune infiltration, as well as the current small-molecule inhibitors of PAKs and their mechanisms. Full article

Male infertility is often linked to sperm quality issues; however, the mechanisms behind these alterations remain unclear in certain contexts. This study investigates the impact of anomalous Rho GTPase activation—a process triggered by bacterial toxins—on human sperm structure and function. Human spermatozoa were exposed in vitro to a Rho GTPase activator derived from Escherichia coli under both capacitating and non-capacitating conditions. The results showed increased RhoA GTPase activity in non-capacitating conditions, without affecting viability or mitochondrial membrane potential. However, progressive motility decreased across both conditions, while non-progressive motility and acrosome reaction rates increased. Additionally, intracellular calcium levels rose exclusively in non-capacitating conditions. Structural analysis revealed an increase in abnormal sperm morphology, particularly vacuoles in the sperm head. These findings highlight that anomalous Rho GTPase activation disrupts essential processes like motility and capacitation, which are crucial for successful fertilization. This study provides novel insights into how bacterial infections may induce sperm damage, proposing that Rho GTPase activity could serve as a biomarker for evaluating sperm quality in cases of infertility linked to urogenital infections. Understanding these mechanisms may improve diagnostic and therapeutic approaches for male infertility associated with bacterial pathogens. Human spermatozoa were exposed in vitro to a Rho GTPase activator derived from Escherichia coli under both capacitating and non-capacitating conditions. Full article