Search Results (173)

The herpes simplex virus 1 (HSV-1) US3 is a multifunctional serine/threonine kinase that promotes HSV-1 replication and spread. But its role and the mechanisms by which US3 regulates actin cytoskeletal remodeling remain poorly defined. We combined flow cytometry, confocal microscopy, immunoprecipitation-mass spectrometry (IP-MS), protein complex mapping, and machine learning to characterize US3-mediated F-actin dynamics. Flow cytometry and confocal microscopy showed that wild-type HSV-1 induces significant F-actin remodeling, while the ΔUS3 mutant displays F-actin levels comparable to uninfected cells, identifying US3 as a key regulator. IP-MS identified 47 high-confidence US3 interactors enriched in conserved actin regulatory complexes, including Arp2/3 nucleation machinery, formin-associated assemblies, cofilin severing complexes, and Rho-family GTPase modules. Mapping interactors to the CORUM database revealed clustering within actin nucleation, polymerization, and severing complexes, indicating that US3 operates through organized cellular machines. Machine-learning classifiers trained on label-independent mass-spectrometry features were used to prioritize interactors resembling known actin regulators; under protein-group-aware cross-validation, logistic regression performed best (average precision 0.24; ROC-AUC 0.66), and the analysis was interpreted as prioritization rather than de novo discovery. Pharmacological inhibition of Arp2/3 and formin pathways significantly attenuated US3-dependent F-actin remodeling, supporting the functional involvement of these pathways. Together, these findings are consistent with an inferred hierarchical axis in which US3 modulates Rho GTPase signaling and cofilin activation to promote F-actin disassembly, coordinating cytoskeletal remodeling required for efficient viral egress and spread. Full article

Rho GTPase-activating proteins (RhoGAPs) are characterized by a conserved RhoGAP domain and function as negative regulators of Rho GTPases, playing important roles in plant growth, development, and responses to environmental stimuli. In this study, 19 GmRhoGAP genes were identified in the soybean genome and found to be unevenly distributed across 11 chromosomes. Comprehensive analyses were performed, including gene structure, conserved motifs, protein domains, gene duplication, synteny, cis-acting elements, tissue-specific expression, and quantitative real-time PCR under rhizobial infection. Structural analysis revealed substantial diversity in intron-exon organization but high conservation of motif composition, with all members containing the conserved RhoGAP domain. A total of 20 segmentally duplicated gene pairs were identified, indicating expansion of the GmRhoGAP family in soybean. Inter-species synteny analysis showed closer evolutionary relationships with Arabidopsis than with rice, and Ka/Ks analysis suggested strong purifying selection during evolution. Promoter analysis indicated potential involvement in development, phytohormone signaling, stress responses, and light responsiveness. Expression profiling demonstrated distinct tissue-specific patterns. qRT-PCR further showed that GmRhoGAP genes respond differentially to rhizobial infection, with 10 generally upregulated genes and 4 downregulated genes. These analyses provide a framework for understanding this gene family and identify candidate genes for future research. Full article

Neuroinflammation plays an essential role in the pathogenesis of several associated brain diseases, including neurodegenerative disorders (Alzheimer’s disease (AD), Parkinson’s disease (PD), multiple sclerosis (MS)), and traumatic brain injury (TBI). In these diseases, persistent microglial and astrocyte aggregates, elevated proinflammatory cytokines, and oxidative stress drive neuronal injury and cognitive disability. Rho GTPases, in particular the Rho family members Ras homolog family member A (RhoA), Ras-related C3 botulinum toxin substrate 1 (Rac1), and cell division control protein 42 homolog (CDC42), regulate neuroinflammation, cytoskeletal dynamics, immune responses, and the maintenance of BBB integrity. These proteins are involved in many neuropathological diseases due to dysregulation, making them interesting therapeutic targets. Bioactives used in herbal care have attracted interest for their ability to influence neuroinflammation and even their anti-neurodegenerative activity. Studies show that flavonoids, alkaloids, polyphenols, and other botanical compounds alter Rho GTPase activity, which, in turn, leads to decreased inflammation. This review critically summarizes current evidence regarding phytochemical regulation of Rho GTPase signaling in neurodegenerative disorders such as Alzheimer’s disease (AD) and Parkinson’s disease (PD), with particular emphasis on the underlying molecular mechanisms, context-dependent signaling responses, and current translational challenges. Furthermore, existing knowledge gaps and future research priorities are discussed to facilitate the development of mechanism-based therapeutic strategies targeting Rho GTPases. Full article

Based on their domain organisation, four proteins from the protist Dictyostelium discoideum have been assigned to the IQGAP family of scaffold proteins. Although these proteins are shorter than animal IQGAPs, their involvement in the regulation of the actin cytoskeleton in cell motility, macroendocytosis, cytokinesis, and adhesion appears to be broadly conserved between these evolutionarily distant organisms. In this article, we show that the putative three-dimensional structure of Dictyostelium IQGAP-related proteins, as predicted by AlphaFold 3, closely corresponds to the C-terminal half of human IQGAP1, thus supporting their common origin. IqgD is the largest IQGAP-related protein in Dictyostelium, with an overall domain organisation similar to human IQGAPs. IqgD is localised in the cell cortex, interacts with F-actin and Rac1 GTPases, and primarily supports cell adhesion to the underlying surface and cell growth on bacterial lawns. DGAP1 and GAPA are truncated proteins that have retained a 700-residue-long C-terminal region of homology compared to their animal relatives. They play important, yet opposite, roles in regulating contractile cortical assemblies comprising F-actin, myosin II, and the actin-bundling proteins cortexillins, which are especially important for cytokinesis and epithelial morphogenesis. Finally, IqgC, although structurally resembling other IQGAPs, turns out to be more closely related to GAP1 proteins from fungi. This multifaceted protein carries RasGAP activity, interacts with several other small GTPases, and positively regulates macroendocytosis and cell–substratum adhesion. Full article

Toxin A and B from Clostridioides difficile are the main pathogenicity factors for clinical symptoms of C. difficile infections. Receptor-mediated endocytosis and endosomal escape are required for targeting substrate proteins of the Rho-GTPase family. We previously reported that Toxin B (TcdB) affects endo-lysosomal transport and autophagic flux of target cells. These effects are independent from pathogenic Rho inhibition. Here, we aimed at further characterization of this event by immunofluorescent characterization of the vesicular structures that are affected. We found large aggregates of damaged endolysosomal structures positive for EEA1, LAMP1, CHMP4B and TcdB, as well as an increase in perinuclear concentration of non-mature autophagosomes (amphisomes) positive for SQSTM, Rab7, and LC3B. We investigated whether Rab7, a regulator of late endosome transport, is causative for decreased lysosome function. Although TcdB induced an increase in active Rab7, as tested by an RILP pull-down assay, inhibition of Rab7 did not prevent TcdB-induced decrease in cathepsin D as a surrogate for lysosome dysfunction. It also indicates that the observed increase in Rab7 positive amphisomes is secondary to lysosomal dysfunction. By applying an autoproteolytic deficient mutant of TcdB we proved that the release of the glucosyltransferase domain is mandatory for triggering all of these effects. This suggests that after membrane perforation the toxin remnants leave an open leak in endolysosomes affecting ion homeostasis. Investigation of all large clostridial glucosyltransferases and other toxins revealed lysosomal dysfunction as a general effect of many but not of all toxins that integrate into the endosome membrane. Full article

Oligodendroglial cells are the myelinating glial cells of the central nervous system (CNS), and their morphological differentiation is a prerequisite for efficient myelin formation, which is essential for proper neuronal function. While oligodendroglial morphological changes normally proceed through tightly regulated developmental transitions, disruption of the underlying molecular mechanisms can lead to aberrant cellular phenotypes characterized by either premature, insufficient, or excessive differentiation. Although the phosphatidylinositol 3-kinase (PI3K) and its downstream Akt kinase signaling are well established as major drivers of oligodendrocyte morphological differentiation, myelination, and CNS white matter formation, how its negative regulator, phosphatase and tensin homolog (PTEN), is involved in the regulation of oligodendroglial morphogenesis remains incompletely understood. Recent genetic studies have highlighted a spectrum of disorders caused by PTEN dysfunction, conceptually established but currently evolving as PTENopathy, which has been partially associated with white matter abnormalities. Here, we report that, in an experimental model using the FBD-102b cell line, a well-established model of oligodendroglial cell differentiation, chemical inhibition of PTEN enhances pronounced morphological changes characterized by widespread membranes, accompanied by increased expression of differentiation and/or myelin marker proteins. We then focused on Rho family small GTPases, central regulators of cell morphogenesis, and examined their potential involvement downstream of this signaling. Expression of the RhoG-binding domain (RBD) of engulfment and cell motility 1 (ELMO1) attenuated the increased morphological changes. Similarly, inhibition of downstream Akt signaling also reversed these changes. Taken together, these results provide insight into how balanced regulation between PTEN and downstream signaling molecules governs oligodendroglial cell differentiation and suggest that dysregulation of this signaling equilibrium may contribute to cellular phenotypes relevant to disease-associated cellular alterations. Full article

Phagocytosis and migration in macrophages share key regulators, including Rho family GTPases; however, whether phagocytic membrane extension generates a transient, whole-cell polarity that coordinates migration and spatial prioritization of engulfment remains unclear. Here, we investigated the spatiotemporal coupling between membrane extension and cell migration using opsonized microneedles, which enable controlled stimulation together with long-range membrane extension and backtracking dynamics. During single-needle stimulation, membrane extension was tightly coupled to directional migration, whereas membrane retraction showed weaker coupling. In sequential stimulation with two microneedles, ongoing phagocytosis suppressed competing membrane extension at spatially opposite locations, and a reversal in migration direction was accompanied by initiation of membrane extension toward the second needle. Third-needle experiments further revealed a polarized spatial distribution of phagocytic responsiveness across the cell surface. Consistently, uniform stimulation with multiple opsonized microbeads demonstrated sequential, one-at-a-time engulfment even under near-simultaneous target attachment. These results support a model in which phagocytic membrane extension establishes transient, whole-cell polarity that spatially gates engulfment and coordinates whole-cell migration. The microneedle manipulation platform provides a powerful approach for dissecting the spatiotemporal regulation of phagocytosis and for understanding macrophages as adaptive living micromachines integrating mechanical inputs, transient polarity formation, and sequential target processing. Full article

Background: Glabridin, a natural compound derived from Glycyrrhiza glabra L., possesses skin-lightening effects. This study aims to further elucidate the depigmentation mechanism of glabridin by investigating its effects on melanogenesis and melanin transfer. Methods: We initially confirmed the anti-melanogenic effects of glabridin in MNT-1 human melanoma cells. Then, we investigated the mechanism of its anti-melanogenic effect by evaluating the protein expression of β-catenin and MITF via Western blot. To investigate melanin transfer, we compared glabridin’s efficacy with that of niacinamide, a recognized inhibitor of melanosome transfer and employed two complementary experimental models: (1) α-melanocyte-stimulating hormone (α-MSH)-stimulated MNT-1 cells to analyze dendrite formation, and (2) a UVB-irradiated co-culture system of MNT-1 cells and HaCaT keratinocytes to evaluate melanin transfer. Results: By measuring glabridin’s effects on melanin content, tyrosinase activity, and melanogenesis-related protein expression confirmed its inhibition of melanin synthesis. Further investigation demonstrated that glabridin suppresses melanogenesis by downregulating β-catenin and MITF, indicating inhibition of the Wnt/β-catenin pathway. Furthermore, in α-MSH-treated MNT-1 cells, both glabridin and niacinamide were found to suppress dendrite formation and elongation. In a UVB-exposed co-culture system, both glabridin and niacinamide inhibited melanin transfer to keratinocytes. Mechanistically, these effects were linked to the regulation of Rho GTPases (Rac1, RhoA, Cdc42) and suppression of F-actin reorganization. Conclusions: This study provides, for the first time, evidence that the skin-lightening effect of glabridin involves two complementary mechanisms: inhibition of melanogenesis through suppression of the Wnt/β-catenin pathway, and attenuation of both dendricity and melanin transfer via the influence of Rho family GTPases expression. Full article

Chronic obstructive pulmonary disease (COPD) is a leading cause of mortality worldwide, yet only a fraction of smokers develops the disease, suggesting protective mechanisms in resilient individuals. Identifying airway-localized molecular signatures may improve our understanding of disease pathomechanisms and support hypothesis generation for biomarker research. In this pilot study, induced sputum from smokers with COPD (n = 28) and smokers without COPD (n = 16; Global Initiative for Chronic Obstructive Lung Disease (GOLD)-defined pre-COPD) was analyzed by untargeted proteomics, metabolomics, and lipidomics. After quality control, 1180 proteins, 187 metabolites, and 1234 lipids were retained. Analyses included univariate models with false discovery rate adjustment and multivariate analyses (PCA, PLS-DA), followed by pathway enrichment and protein interaction network analysis. While few features remained significant after FDR correction, consistent cross-omics patterns were observed. COPD was characterized by ↑ glutathione, creatine, and L-arginine; ↓ CCDC88A and ↑ STAT3 and SYDE2; and broad lipid remodeling involving phosphatidylcholines, sphingolipids, and eicosanoids. Network analysis highlighted STAT3 as a highly connected node linking COPD-related genes. These findings suggest that the multi-omic profiling of induced sputum can capture coherent airway-localized molecular signatures such as oxidative stress, cytoskeletal remodeling, and Rho-family GTPase signaling. However, the results should be interpreted as exploratory and require validation in functional studies. Full article

Maternal nutrient restriction (MNR) heightens disease susceptibility in offspring through epigenetic modifications that alter the development of essential organs. This study investigates how restriction alters the fetal sheep hepatic methylome and its potential regulatory influence on gene expression. Using a monozygotic twin model generated through embryo splitting, we examined hepatic DNA methylation responses to maternal nutrient restriction (50% vs. 100% NRC nutritional requirements; n = 4 per group) from gestational day (GD) 35 to 135 in pregnant sheep. At GD 135, conceptus (fetal–placental unit) development was assessed; although fetal weight was unaffected (p > 0.10), restricted fetuses exhibited reduced liver mass (p < 0.05). Whole-genome bisulfite sequencing (WGBS) of fetal liver identified 1,636,305 differentially methylated CpG sites (dmCpGs) in the Group-Level Analyses and 42,231 dmCpGs in the Twin-Pair Analyses. At the Group-Level, 40,533 promoter, 126,667 exonic, and 785,381 intronic sites were identified, whereas the Twin-Pair subset contained 1314, 7116, and 22,239, respectively. Site-level shifts and functional enrichment across features highlighted GPCR–cAMP/calcium–PI3K/AKT signaling, phosphoinositide metabolism, ECM/integrin–focal adhesion networks, thyroid hormone signaling, and Rho-family GTPases. These findings indicate that maternal nutrient restriction modifies the fetal hepatic methylome through coordinated signaling, metabolic, and structural reconfigurations that create conditions conducive to metabolic disease. Full article

RhoA (Ras homolog A) is a prominent member of the Rho GTPase family, playing a key role in various cellular processes such as cytoskeletal dynamics, cell migration, and immune responses. However, its function in red swamp crayfish remains unclear. In this study, it is proposed that RhoA may regulate the innate immune response in P. clarkii. The gene was fully characterized as PcRhoA in P. clarkii. The results showed that the open reading frame (ORF) of PcRhoA is 663 bp, encoding a 220-amino acid protein with a conserved Rho domain of 174 amino acids. Phylogenetic analysis placed PcRhoA close to Cherax quadricarinatus RhoA. RT-qPCR analysis revealed high expression levels of the PcRhoA gene in the hepatopancreas, muscle, heart, ovary, and stomach, with lower expression in the blood, intestine, gills, and tentacle gland. Furthermore, PcRhoA mRNA transcript was significantly upregulated in the intestine following LPS and Poly I:C challenges. Knockdown of PcRhoA suppressed the expression of downstream genes in the immune signaling pathway. These results indicate that PcRhoA appears to play a pivotal role in regulating the immune response of crayfish. Full article

The present review aims to provide a comprehensive overview of the current literature on Adams–Oliver syndrome (AOS), synthesizing information on its clinical features, genetic and molecular underpinnings, nutritional aspects, and key nursing care considerations. AOS is a rare congenital disorder. Its genetic basis is heterogeneous, involving mutations in at least six key genes (ARHGAP31, RBPJ, NOTCH1, DLL4, DOCK6, and EOGT), which primarily affect vascular development through pathways like Notch signaling and Rho GTPase regulation. The management of AOS is complex and requires a multidisciplinary approach. The clinical presentation of AOS is highly variable, ranging from mild to severe and includes a wide spectrum of clinical manifestations, most notably aplasia cutis congenita and terminal transverse limb defects. The underlying molecular mechanisms predominantly point towards vasculopathy, disrupting embryonic development. Emerging evidence also highlights the presence of nutritional issues, such as poor feeding and growth failure, which are often overlooked. Management demands an integrated, multidisciplinary management approach, requiring coordinated effort from specialists in pediatrics, genetics, molecular biology, cardiology, surgery, and nutrition. Specialized nursing care is crucial for managing complex symptoms, particularly wound care for aplasia cutis, and for providing family support. Full article

Extracellular vesicles (EVs) secreted by Fusarium oxysporum play an important role in the process of its infestation of the host, but the in vitro research system for EVs of F. oxysporum (Fo-EVs) has not yet been improved, and the mechanism of its action remains unclear. In this study, particle size distribution, particle concentration, number of particles per unit of protein, number of particles per unit of mycelial biomass, and concentration of contaminated proteins were used as indicators to evaluate the yield and purity of Fo-EVs. The optimal method for Fo-EV preparation and extraction was screened by comparing liquid culture, solid culture, and solid culture with enzymatic cell wall hydrolysis. The optimal system for Fo-EVs separation and purification was screened by a pairwise combination of three primary methods (Ultracentrifugation (UC), Ultrafiltration (UF), and Polyethylene glycol precipitation method (PEG)) and two secondary methods (Size-exclusion chromatography (SEC) and Aqueous two-phase system (ATPS)), respectively. The protein composition was identified via mass spectrometry technology, followed by GO annotation and GO enrichment analysis using whole-genome proteins as the background. Based on these steps, a Fo-EV protein library was constructed to reveal Fo-EV’s most active biological functions. The results showed that solid culture combined with the UC-SEC method could effectively enrich Fo-EVs with a typical cup-shaped membrane structure. The obtained Fo-EVs had an average particle size of 253.50 nm, a main peak value of 200.60 nm, a particle concentration of 2.04 × 10¹⁰ particles/mL, and a particle number per unit protein of 1.09 × 10⁸ particles/μg, which were significantly superior to those of other combined methods. Through proteomic analysis, 1931 proteins enriched in Fo-EVs were identified, among which 350 contained signal peptides and 375 had transmembrane domains. GO enrichment analysis revealed that these proteins were mainly involved in cell wall synthesis, vesicle transport, and pathogenicity-related metabolic pathways. Additionally, 9 potential fungal EV markers, including Hsp70, Rho GTPase family, and SNARE proteins, were screened. This study constructed an isolation system and a marker database for Fo-EVs, providing a methodological and theoretical basis for in-depth analysis of the biological functions of Fo-EVs. Full article

Background/Objectives: Rho small GTPases (RSG), which regulates metastasis, constitute eight subfamilies—“classical” Rho, Rac, cdc42, and “atypical” Rif, Rnd, Wrch, RhoH, and RhoBTB. Their downstream signaling requires switching between GTP-bound active and GDP-bound inactive forms. Classical RSGs, but not atypical RSGs, require regulation by guanine nucleotide exchange factors (GEF), GTPase-activating proteins (GAP) and guanine nucleotide dissociation inhibitors (GDI) to achieve this switch. The objective of this review is to summarize the roles of RSGs in metastatic prostate cancer (mPCa) and their interaction with the androgen receptor (AR), which regulates this disease. Methods: We summarize the literature that describes the role of RSGs in mPCa, and their interaction with the AR. Results: Classical RSGs mostly promote metastasis (except RhoB), whereas atypical RSGs, with exceptions, mostly prevent it. Their role, however, is context-dependent—e.g., RhoB is tumor-suppressive in AR-null PCa but oncogenic in AR-positive tumors. The AR modulates RSG expression transcriptionally, but also affects their function through modulation of GEFs, GAPs, and GDIs. In turn, RSGs also regulate AR transcriptional activity. Interestingly, RSGs and the AR have non-genomic interactions via membrane-localized AR (mAR) not affected by AR inhibitors. Conclusions: Drugs that target RSGs are needed along with AR inhibitors to prevent mPCa progression. 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