Rho GTPases Research Articles

Interplay between Rac1/RhoA and actin waves in giant epithelial cells: experiment and theory.

How can a cell navigate its environment without any external cues? Since such cues are not always present in the environment, cells rely on internal machinery to explore their surroundings. Although Rho GTPases are known for orchestrating cell motility, the intrinsic Rho GTPase-effector mechanisms governing spontaneous migration remain incompletely understood. Here we show an imaging-based method that profiles protein-protein interactions (PPIs) through phase-separated condensates. By applying this method to hundreds of interaction profiles between Rho small GTPases and their effector proteins, we uncovered two intrinsic mechanisms governing cell migration. Formin-like protein (FMNL) determines the front of the cell by restricting Cdc42 activity, establishing front-rear polarity. In contrast, Rac1-ROCK-interaction-mediated arc stress fiber formation at the front inherently enables spontaneous directional changes and enhances cellular responses to external cues. Our findings elucidate the intricate roles of the Rho GTPase-effector ensemble that governs cell migration behavior, revealing an intrinsic program for efficient motility strategies.

BRI3BP, an RNA-binding protein upregulated in multiple cancers, plays an undefined role in hepatocellular carcinoma (HCC). This study investigates its diagnostic and prognostic potential in HCC. Multi-omics analysis of TCGA and GEO data identified BRI3BP-interacting genes and enriched pathways. Genomic and epigenetic alterations were assessed using cBioPortal and MethSurv. Immune infiltration was profiled via ssGSEA and TIMER 2.0. Prognostic relevance was validated through survival analysis, Cox regression, and experimental assays. BRI3BP was overexpressed in HCC and correlated with advanced tumor stage, shorter overall survival (OS), and disease-free survival (DFS). Functional enrichment linked BRI3BP to cell cycle regulation, Rho GTPase activity, and copper homeostasis. Analysis of transcriptomic data revealed that BRI3BP expression also significantly correlated with immune cell infiltration and an immunosuppressive microenvironment, validated by immunohistochemistry showing reduced CD8 + and increased CD68 + cells in high-BRI3BP samples. In vitro, BRI3BP overexpression promoted HCC cell migration and invasion and activated the ROCK signaling pathway, suggesting potential involvement in tumor progression. Drug sensitivity assays confirmed lower lapatinib IC50 in overexpression models. High BRI3BP expression correlates with aggressive HCC phenotypes, poorer survival, and dysregulated oncogenic pathways, supporting its role as a prognostic biomarker and candidate therapeutic target.Supplementary InformationThe online version contains supplementary material available at 10.1038/s41598-025-22072-5.

Glioblastoma (GBM) is a highly aggressive tumor primarily treated through surgery, radiotherapy, and chemotherapy. GBM radioresistance involves the activation of the Rho GTPase pathway, actin cytoskeleton polymerization, and the cytoplasmic retention of wild-type p53. Activation of DNA damage response (DDR) pathways and double-strand break (DSB) repair depends on the cytoplasmic availability of G-actin and its nuclear translocation, which facilitates p53 nuclear transport. In this study, we investigated whether DNA damage repair pathways induced by cisplatin (CP) and temozolomide (TMZ) are dependent on Rho pathway activity and actin cytoskeleton dynamics by generating chemoresistant GBM sublines. GBM cells expressing wild-type p53 displayed activation of the Rho pathway and actin polymerization when treated with TMZ or CP, but showed reduced activation of DNA repair signaling, as well as lower levels of p-p53 (Ser15), and p21Cip1. TMZ-resistant clones exhibited constitutive Rho pathway activity, elevated p53 levels, and activation of DDR and DSB repair pathways, but displayed reduced levels of mismatch repair (MMR) proteins. Notably, inhibition of Rho GTPases restored the sensitivity of TMZ- and CP-resistant clones, reversing either transient or permanent chemoresistance in a process entirely dependent on wild-type p53. GBM cells harboring mutant p53 treated with PRIMA-1 also regained sensitivity to chemotherapy following Rho pathway inhibition. These findings were corroborated in GBM spheroid tumor models treated with TMZ and CP under actin cytoskeleton polymerization inhibition. In summary, modulating Rho pathway activity and actin cytoskeleton dynamics is crucial for both the development and reversal of chemoresistance in GBM.

Arrhythmogenic cardiomyopathy (ACM) is an inherited heart disease marked by progressive fattyfibro replacement of the ventricular myocardium, life-threatening arrhythmias, and sudden cardiac death. To dissect epicardial contributions to ACM pathogenesis, we generated iPSC lines from patients carrying plakophilin 2 (PKP2) 1849C > T or PKP2 2013delC mutations, their CRISPR/Cas9–corrected isogenic controls, and a PKP2 knockout line. Epicardial cells (hPSC-EPCs) differentiated from mutant and knockout backgrounds exhibit enhanced epithelial-to-mesenchymal transition characteristics, increased lipid accumulation, and a pronounced fibrotic phenotype. RNA-seq performed on ACM hPSC-EPCs reveals dysregulation of Wnt, interferon, and Rho GTPase signaling, including an upregulation of insulin growth factor 2 (IGF2) and a key adipogenic transcription factor, CEBPA. Subsequent treatment of control and PKP2KO hPSC-EPCs with recombinant IGF2 enhances CEBPA expression, suggesting that insulin growth factor signaling contributes to ACM fattyfibro remodeling.

BackgroundThe Rho GTPase-activating protein (RhoGAP) family represents a large and diverse group of proteins that act as key regulators of Rho GTPases, small GTP-binding proteins involved in cellular signaling. Tight regulation of Rho GTPase activity is essential for fundamental biological processes, including cell motility, contractility, growth, differentiation, and development. Despite their biological importance, the roles of RhoGAPs in cancer remain largely undefined.MethodsBioinformatics analysis was performed using data from The Cancer Genome Atlas (TCGA), covering over 10,000 samples across 33 cancer types. The role of ARHGAP11A in the DNA damage response was evaluated through single-cell sequencing, western blotting, and colony formation assays.ResultsPan-cancer analysis of RhoGAP family genes identified ARHGAP11A as the most significantly overexpressed member in tumors compared to adjacent normal tissues. ARHGAP11A expression was found to be elevated in most cancer types and was associated with DNA repair activity. Furthermore, its expression positively correlated with tumor mutational burden (TMB), a recognized predictive biomarker for immunotherapy. Intriguingly, it also correlated with increased infiltration of regulatory T (Treg) cells, which are known to suppress anti-tumor immunity. Consistent with these observations, high ARHGAP11A expression was concurrently linked to poor patient survival outcomes across multiple cancers. We also observed a positive correlation between ARHGAP11A and CHK1, suggesting a functional collaboration. In vitro experiments further demonstrated that ARHGAP11A confers resistance to DNA damage induced by CHK1 inhibitors.ConclusionARHGAP11A is a promising prognostic marker in cancer, with potential therapeutic implications through targeting DNA repair pathways and modulating the tumor immune microenvironment.Supplementary InformationThe online version contains supplementary material available at 10.1186/s12885-025-15106-8.

Acute myeloid leukemia (AML) is a heterogeneous hematologic malignancy associated with poor clinical outcomes. RHOBTB2, an atypical member of the Rho-GTPase family, contains a conserved GTPase domain at its N-terminus. While previous studies have implicated RHOBTB2 in AML progression, its underlying mechanisms remain inadequately defined. In this study, bioinformatics analyses revealed that RHOBTB2 is markedly upregulated in AML and correlates with unfavorable prognosis. To elucidate its functional role, we overexpressed or silenced RHOBTB2 in human AML cell lines KG-1 and MOLM-13. Functional assays, including CCK-8, Transwell, and Annexin V/PI staining, demonstrated that RHOBTB2 overexpression enhanced proliferation and migration, suppressed apoptosis, and shortened G0/G1 phase. Conversely, RHOBTB2 silencing exerted opposing effects. In addition, a direct interaction between RHOBTB2 and KLHL13 was identified through STRING database predictions and validated by co-immunoprecipitation. Western blot analysis confirmed that RHOBTB2 upregulates KLHL13 protein expression levels. Notably, KLHL13 downregulation induced by RHOBTB2 knockdown was reversed upon treatment with the proteasome inhibitor MG132, indicating that RHOBTB2 stabilizes KLHL13 by inhibiting its proteasomal degradation. Collectively, our findings highlight the RHOBTB2/KLHL13/Hippo pathway as a critical regulatory mechanism in AML malignancy and suggest RHOBTB2 as a potential therapeutic target.Supplementary InformationThe online version contains supplementary material available at 10.1038/s41598-025-20492-x.

Charcot-Marie-Tooth Disease is a clinically and genetically heterogeneous group of hereditary neuropathies. Despite progress in genetic sequencing, around a quarter of patients remain unsolved. Here, we identify 16 recessive variants in the RhoGTPase activating protein 19 gene (ARHGAP19) causing motor-predominant neuropathy in 25 individuals from 20 unrelated families. The ARHGAP19 protein acts as a negative regulator of the RhoA GTPase. In vitro biochemical and cellular assays revealed that patient variants impair the GTPase-activating protein (GAP) activity of ARHGAP19 and reduce ARHGAP19 protein levels. Combined in vitro and in vivo studies reveal that human ARHGAP19, and conserved ARHGAP19 orthologs in Drosophila and Zebrafish, influence motoneuron morphology and promote locomotor capacity. Transcriptomic studies further demonstrate that ARHGAP19 regulates cellular pathways associated with motor proteins and the cell cycle. Taken together, our findings establish ARHGAP19 variants as a cause of inherited neuropathy acting through a loss-of-function mechanism.

Leaves are built from multiple cell types and are structured to enable the conversion of carbon dioxide and water into sugars in the process of photosynthesis. Understanding how cell architecture impacts the movement of CO2 within leaves may provide means to improve photosynthesis. Here, we examined the impact of mesophyll cell architecture on air networks and air permeability by employing high-resolution tomography data in leaves of Arabidopsis thaliana wild-type plants and in plants with altered Rho of Plant (ROP)-GTPase-related activities. We employed high-resolution tomography to characterise leaf cell architecture and associated air space networks. The image data were segmented and analysed using machine learning, and combined with leaf gas exchange measurements to evaluate photosynthesis-related traits. We found that changes in the ROP-GTPase pathway substantially altered the leaf cell architecture, causing disruptions in the air space network associated with higher tortuosity. In addition, changes in ROP-GTPase activity resulted in reduced mesophyll conductance. Our observations underscore how changes in leaf cell architecture potentially drive alterations in photosynthesis-related traits, highlighting a mechanistic link between mesophyll geometry, air space organisation, and CO2 diffusion.

Auxin plays a critical role throughout plant development. We have established earlier that auxin activates the ROP (plant RHO GTPase) molecular switch, and that guanine nucleotide exchange factors ROPGEFs, which activate ROPs, are important regulators for myriad auxin-regulated processes. Here we show that auxin induces phosphorylation of RopGEF1 and that four receptor-like cytoplasmic kinases (RLCKs), named RopGEF1-activating kinases 1/2/3/4 (RAK1/2/3/4), mediate this process. We show that RAKs interact with RopGEFs and specifically phosphorylate S488 on RopGEF1, promoting its stability and recruitment to the cell membrane, and enhance ROP activation. Knockout of these RLCKs blocked auxin-stimulated RopGEF1 phosphorylation, reduced ROP activation and led to defects in PIN-FORMED (PIN)-mediated auxin distribution and multiple developmental processes. Phospho-mimic RopGEF1 (S488D) shows enhanced guanine nucleotide exchange activity in vitro, and its expression in rak quadruple mutants reverses their phenotypes. The RLCK-RopGEF linkage represents an important functional node and elucidates a critical missing link in ROP-meditated auxin signaling.

BackgroundDistant metastasis is a primary factor contributing to the significantly shorter survival time of patients with advanced lung adenocarcinoma. The transcription factor Kruppel-like factor 5 (KLF5) facilitates the progression of lung adenocarcinoma. However, the specific mechanism by which KLF5 is involved in the tumor metastasis of lung adenocarcinoma metastasis remains largely unclear.MethodsUsing bioinformatic analysis, Rhophilin Rho GTPase Binding Protein 2 (RHPN2) was identified as a potential downstream target gene for KLF5; it plays a crucial role in the regulation of the epithelial-mesenchymal transformation pathway in lung adenocarcinoma. Western blotting and immunohistochemistry were performed to examine RHPN2 expression in lung adenocarcinoma. In vivo and in vitro experiments were conducted to explore the regulatory role of RHPN2 on the cell growth and metastasis of lung adenocarcinoma. Chromatin immunoprecipitation sequencing was used to analyze the direct binding activity between KLF5 and RHPN2 promoter regions. Luciferase activity assay was performed to verify the transcriptional activation effect of KLF5 on RHPH2.ResultsRHPN2 was highly expressed in lung adenocarcinoma; patients with lung adenocarcinoma who showed high RHPN2 expression had a poor prognosis. In vivo and in vitro experiments showed that RHPN2 promoted cell growth and metastasis and activated the epithelial-mesenchymal transformation pathway in lung adenocarcinoma. KLF5 directly bound to the promoter region of RHPN2 and upregulated its expression in lung adenocarcinoma through transcriptional activation. In addition, rescue experiments confirmed that KLF5 facilitated the progression of lung adenocarcinoma in an RHPN2-dependent manner.ConclusionOur study offers insights into the potential mechanisms of metastasis in lung adenocarcinoma and highlights RHPN2 as a potential therapeutic target.Supplementary InformationThe online version contains supplementary material available at 10.1186/s12967-025-07150-6.

The CNF1 toxin from extraintestinal pathogenic Escherichia coli (ExPEC) deamidates glutamine 61 of Rac1 small GTPase, as well as its equivalents in RhoA and Cdc42 into glutamic acid. This post-translational modification of Rho proteins abrogates the hydrolysis of GTP into GDP, thereby enhancing signal transduction. Meanwhile, the sustained GTP-loading of Rac1 Q61E sensitizes it to ubiquitin-mediated proteasomal degradation catalyzed by the HACE1 E3 ligase rate-limiting factor, leading to a cellular depletion of Rac1 over time. We report data from a quantitative genome-wide screen of siRNAs inhibiting CNF1-mediated cellular depletion of Rac1 in primary human cells. As best hits, we identified a group of three siRNAs targeting the Sec61A1 subunit of the Sec61 translocon, as well as HACE1 and the Lu/BCAM host cell receptor of CNF1. We extend these findings by identifying a group of siRNAs targeting genes involved in ER and Golgi homeostasis and trafficking. Functional studies showed that both chemical and genetic inhibition of Sec61A1 dampens GTP-loading and membrane association of Rac1 in CNF1-intoxicated cells, while the proper deamidation of RhoA provides a control of CNF1 cytosolic action. Finally, we extend these findings by showing that inhibition of N-glycosylation of neo-synthesized proteins in the ER abrogates Rac1 GTP-loading in CNF1-treated cells. Collectively, these data point to a control of Rac1 signaling operated by protein biosynthesis and N-glycosylation in the ER.IMPORTANCEThe remarkable evolutionary convergence of bacterial effectors from pathogens toward the host small GTPase Rac1, the master regulator of the actin cytoskeleton, confers to these microbes an enhanced capacity to invade host cells and tissues. The CNF1 toxin, a colonization factor of the gastrointestinal tract produced by pathogenic strains of Escherichia coli, has been instrumental in deciphering the regulation and function of Rac1. By performing a whole-genome screen based on CNF1 action, we establish the key requirement of Sec61 translocon-dependent protein biosynthesis and N-glycosylation at the endoplasmic reticulum for proper activation of Rac1 in intoxicated cells. Our data connect the Sec61 translocon and N-glycosylation of neo-synthesized proteins at the endoplasmic reticulum in the control of the activity of Rac1 and other Rho GTPases.

Syphilis, caused by Treponema pallidum subsp. pallidum, is an urgent global public health threat. Syphilis vaccine development has been impeded by limited understanding of the molecular mechanisms that enable T. pallidum to establish and maintain infection. The vascular endothelium is critical for T. pallidum attachment, dissemination, and host immune response initiation; however, the molecular details of T. pallidum-endothelial interactions are incompletely understood. To enhance understanding, we performed time-course transcriptomic profiling on T. pallidum-exposed brain microvascular endothelial cells. These analyses showed T. pallidum exposure altered pathways related to extracellular matrix, growth factors, integrins, and Rho GTPases. The induced transcriptional response was consistent with endothelial to mesenchymal transition, a process involved in fetal development and vascular dysfunction. In cells exposed to T. pallidum, the primary transcription factor associated with this process (Snail) was increased at both the transcript and protein levels, and microscopy analyses demonstrate F-actin cellular contraction. This study provides a comprehensive understanding of the molecular responses of endothelial cells to T. pallidum and identified the host pathways that might cause syphilis disease symptoms, information that could aid in syphilis vaccine design.

A highly sensitive and stable biosensor was crucial for the early screening and treatment of diseases. As one of the most promising and powerful platforms, AlGaN/GaN HEMT biosensors have enormous potential owing to their distinctive 2DEG channel features. While gold nanomaterials offer great potential for creating highly sensitive sensing surfaces due to their nanoscale size, their lack of robustness and inconsistent concentration on the HEMT surface hinders the reliability and reproducibility of biosensors. Herein, gold nanoislands (AuNis) are utilized for the first time as a sensing membrane on AlGaN/GaN HEMT devices for biosensing applications. The high sensitivity for pH detection verified the excellent AuNis sensing capability. For biosensing applications, glutathione S-transferase–p21-activated kinase1–GTPase-binding domain (GST-PAK1-GBD; residues 56–272) served as a bioreceptor for small Rho GTPases in Jurkat T-cell lysate detection, achieving high current and voltage sensitivities of 9.10% and 33.00% at 3 × 10⁻⁷ g/mL, respectively. Benefitting from the large surface binding site of the AuNis sensing surface, a wider range of Jurkat T-cell lysate detection from 3 × 10−16 to 3 × 10−7 g/mL and an ultra-low limit of detection of 3 × 10−16 g/mL are obtained. Furthermore, excellent reproducibility with a reported correlation coefficient (R2 ≥ 0.950) across multiple sensors and > 98% signal recovery after regeneration cycles further validates the sensor’s performance and reusability. The modification of the sensing surface with AuNis marks a significant advancement toward the development of robust and reproducible biosensors.

Metabolic disorders are common in women with breast cancer, raising mortality and recurrence rates, but their causes remain poorly understood. Given the importance of skeletal muscle metabolism in glucose homeostasis, we investigated the effect of breast cancer cell-conditioned media on insulin-stimulated glucose uptake in muscle. Rat L6myotubes overexpressing myc-tagged GLUT4 were incubated with 40% conditioned media from tumourigenic MCF7 or BT474, or non-tumourigenic control MCF10A breast cells. Mass-spectrometry-based proteomics was applied to detect molecular rewiring in response to breast cancer in the muscle. Expression of myogenesis and inflammation markers, GLUT4 translocation, [3H]2-deoxyglucose uptake, and intramyocellular insulin signalling were determined. Breast cancer cell-conditioned media induced proteomic changes in pathways linked to sarcomere organisation, actin filament binding and vesicle trafficking. Myogenic differentiation was disrupted, marked by a 50% increase in Mki67mRNA and trend (P=0.087) towards reduced myosin heavy chain expression, as shown by immunofluorescence. Additionally, breast cancer cell-conditioned media activated inflammation via nuclear factor-κB and interleukin-6signalling and reduced myotube width by 70% (P=0.0524). Myotubes treated with breast cancer cell-conditioned media had a reduced basal and insulin-stimulated GLUT4 translocation and glucose uptake. Insulin signalling via the Rho GTPase Rac1 was reduced by 40%, while absolute Akt-TBC1D4 phosphorylation was unaffected. Conditioned media from MCF7 and BT474 breast cancer cells altered skeletal muscle proteome, induced inflammation, lowered growth markers, reduced glucose uptake, inhibited GLUT4 translocation and blocked insulin-stimulated Rac1 activation. These findings indicate that the rewiring of skeletal muscle could play a role in metabolic dysfunction in patients with breast cancer. KEY POINTS: Metabolic disorders in breast cancer increase mortality and cancer recurrence. Here, we show that incubation with breast cancer cell-conditioned media (CM) alters the proteome in rat skeletal muscle cells. In addition, breast cancer CM activates NF-κB and type 1 interferon pathways, inhibiting muscle growth. Moreover, breast cancer CM inhibits basal and insulin-mediated GLUT4 translocation and glucose uptake, likely by blocking insulin-stimulated Rac1, but not Akt-TBC1D4 activation. These results underscore a potential mechanistic link between breast cancer and metabolic disorders and suggest that skeletal muscle rewiring may play a role.

Abstract BACKGROUND Glioblastoma (GB) is an aggressive brain tumor with inevitable recurrence due to the persistence of infiltrative cells in the peritumoral brain. These cells, located in the non-enhancing but FLAIR-hyperintense periphery, are not routinely sampled or molecularly profiled, leaving a gap in our understanding of GB recurrence mechanisms and potential therapeutic targets. METHODS We performed MRI-guided surgical sampling of both the tumor core and periphery in 10 patients with IDH-wildtype GB. Bulk RNA sequencing was conducted on paired samples. To distinguish infiltrated from normal-like peripheral tissues, we developed a 500-gene “tumor-enriched” signature by comparing bulk transcriptomic data from TCGA-GBM (tumor) and GTEx (normal cortex) cohorts. This signature, enriched for cell cycle, DNA replication, and mitosis-related genes, was validated using the Ivy Glioblastoma Atlas dataset. We applied this classifier to our dataset, identifying tumor-enriched and normal-like profiles. Differential expression and gene set enrichment analyses were then performed, and findings were supported by external spatial and single-cell datasets. Functional relevance was assessed through in vitro invasion assays. RESULTS Peripheral samples classified as tumor-enriched showed upregulation of genes involved in invasion, including Rho GTPase signaling and ECM degradation. Gene expression profiles suggested a shift toward an OPC-like phenotype with lower proliferative and higher invasive potential. Among nine underexplored invasion-associated genes, Contactin 2 (CNTN2) emerged as a key candidate. CNTN2 expression was confirmed in the tumor periphery via spatial transcriptomics and immunohistochemistry. Knockdown in 3D tumor models reduced invasiveness. CNTN2-positive cells were enriched in OPC/NPC-like populations and overexpressed in recurrent GB. High CNTN2 levels correlated with shorter survival in two independent GB cohorts (TCGA and Rembrandt et al). CONCLUSION CNTN2 is a promising therapeutic target linked to GB infiltration, recurrence, and poor prognosis. Targeting CNTN2 may help limit tumor invasion beyond the resection margins and represents a potential strategy to improve GB outcomes by focusing on invasive rather than proliferative tumor properties.

Abstract BACKGROUND Glioblastoma multiforme (GBM) is the most aggressive primary brain tumor which characterized by a high ability to migrate and invade into surrounding brain tissue. The main problem in therapy is the tumor’s high invasiveness. The heat shock protein 70 (Hsp70) has a cytoplasmic localization in normal cells but specifically localized on the plasma membrane (mHsp70) of tumor cells which makes it a promising therapeutic target. We investigated the role of mHsp70 in motility of GBM cells. MATERIAL AND METHODS The study was performed using primary human glioblastoma cell cultures (n=4) isolated from biopsy material. The expression of mHsp70 was detected with confocal microscopy, flow cytometry, Western blot, and proteome analysis of lipid rafts. Сells were sorted into two subpopulations - high (mHsp70High) and low expressed mHsp70 (mHsp70Low). The motility characteristics were studied using automatic single-cell tracking and transwell analysis with Hsp70 inhibitors (PES, JG-98) blocking different domains. RESULTS The expression of mHsp70 was observed in 100% of cell populations. The highest content of mHsp70 revealed in lamellipodia and filopodia. Proteomic analysis of lipid rafts identified the interaction of mHsp70 with proteins involved in cytoskeletal remodeling and migration (tubulin-β, tubulin-α4a, myosin IX, filamin A, integrin β-1, α-enolase and the small GTPase RhoA) that may indicate the chaperone participation in the regulation of migration. The mHsp70High subpopulations had a mean speed of 1.5-2 times higher than mHsp70Low. The inhibitors of Hsp70 effectively decrease GBM cells speed. CONCLUSION This study expands our understanding of mHsp70 influence to the migration of GBM cells. The protein expression level correlates with motility. The Hsp70 inhibitors reduces the invasive potential of cells, which allows to use them as an adjuvant agents in the development of novel approaches to the treatment of malignant tumors. Research was funded by the Ministry of Science and Higher Education of Russia (agreement № 075-15-2022-301).

Piezo1 is a mechanosensitive ion channel that mediates a broad range of biological and pathological phenomena in living organisms, including hypertension and hypertensive nephropathy. We previously reported the upregulation of Piezo1 in the glomerular podocytes of hypertensive nephropathy mice in vivo and a mechanical stretch-induced podocyte injury cascade via Piezo1 and Rac1 in vitro, suggesting the pathogenic involvement of Piezo1. However, recent reports on podocyte-specific Piezo1 knockout mice with various podocyte injury models other than hypertension have yielded inconsistent results, indicating pathogenic and anti-pathogenic roles of Piezo1. In this study, we generated podocyte-specific Piezo1 knockout mice and examined their podocyte phenotypes under normotensive and hypertensive conditions induced by angiotensin II and a high-salt diet. Podocyte-specific Piezo1 knockout mice did not spontaneously develop podocyte injury. Angiotensin II infusion and a high-salt diet for 14 days caused hypertension, but not significant podocyte injury and proteinuria in the littermate control mice, which were strengthened by podocyte-specific Piezo1 deletion. Through comprehensive transcriptome analysis of the glomeruli of wild-type and podocyte-specific Piezo1 knockout mice, we found altered expression of several genes, including Rhpn1 encoding Rho GTPase binding protein Rhophilin1. Podocyte injury in hypertensive podocyte-specific Piezo1 knockout mice was inhibited by the angiotensin II receptor blocker losartan, the anti-hypertensive drug hydralazine, and partially ameliorated by the Rho kinase inhibitor fasudil, suggesting that podocyte injury in the knockout mice may be mediated by Rhophilin1 and/or Rho signaling downstream of Piezo1. Findings related to the hypertensive podocyte injury model support the possible anti-pathogenic protective roles of Piezo1. We created podocyte-specific Piezo1 KO mice, and hypertension was induced by angiotensin II and a high-salt diet. Hypertension-evoked proteinuria and podocyte injury were exaggerated in the KO mice. They were ameliorated by anti-hypertensive drugs and Rho kinase inhibitor, suggesting protective roles of Piezo1 and involvement of RhoA signaling.

Physiological functions and structural features of Gα12/13 proteins.

Rho family small GTPases (Rho GTPases) are key regulators of cellular morphology, primarily through their control of the actin cytoskeleton. They play crucial roles in various cellular processes, including cell division, adhesion, and migration. The activity of Rho GTPases is tightly regulated by specific guanine nucleotide exchange factors (GEFs), which facilitate the exchange of GDP for GTP, thereby activating the GTPases. In the human genome, RhoGEFs are categorized into two major families: the DOCK family, comprising 11 members characterized by dedicator of cytokinesis (DOCK) homology regions, and the Dbl family, consisting of 64 members that contain a diffuse B-cell lymphoma (Dbl) homology domain. This review focuses on the pleckstrin homology and RhoGEF domain containing G (PLEKHG) family within the Dbl family of RhoGEFs, which remains largely uncharacterized. We summarize their structure and function, with a particular emphasis on PLEKHG2, discussing its regulatory mechanisms, interactions with various molecules, and its involvement in neural functions.