Liquiritigenin alleviates doxorubicin-induced chronic heart failure via promoting ARHGAP18 and suppressing RhoA/ROCK1 pathway.

Chronic heart failure (CHF) is one of the most common chronic diseases with increasing incidence and mortality. Liquiritigenin (LQG) is shown to protect mice from cardiotoxicity. However, its underlying mechanism remains unclear. Our study aimed to reveal the role of ARHGAP18 in LQG-mediated cardioprotective effects in CHF. In the current study, CHF cell model and rat model were established by the application of doxorubicin (DOX). The reactive oxygen species (ROS) level and cell apoptosis were determined by flow cytometry. The cardiac function of rats was evaluated by measuring left ventricular systolic pressure, left ventricular end diastolic pressure, and serum level of lactate dehydrogenase and brain natriuretic peptide. The expression of active RhoA was elevated and that of ARHGAP18 was decreased in DOX-induced CHF cell model. ARHGAP18 could reduce DOX-induced RhoA activation, ROS elevation, and cell apoptosis. Meanwhile, the knockdown of ARHGAP18 could promote the activation of RhoA, the level of ROS, and the rate of cell apoptosis, which could be reversed by the application of RhoA inhibitor. LQG promoted the expression of ARHGAP18 and exerted similar effects of ARHGAP18 in CHF cell model. The application of LQG could also reverse the effects mediated by ARHGAP18 knockdown. Moreover, LQG significantly improved cardiac function and ameliorated DOX-induced cardiotoxicity of CHF rats. In conclusion, LQG could alleviate DOX-induced CHF via promoting ARHGAP18 and suppressing RhoA/ROCK1 pathway. LQG was a potential agent for CHF treatment.

Rho-Proteins and Downstream Pathways as Potential Targets in Sepsis and Septic Shock: What Have We Learned from Basic Research.

Sepsis and septic shock are associated with acute and sustained impairment in the function of the cardiovascular system, kidneys, lungs, liver, and brain, among others. Despite the significant advances in prevention and treatment, sepsis and septic shock sepsis remain global health problems with elevated mortality rates. Rho proteins can interact with a considerable number of targets, directly affecting cellular contractility, actin filament assembly and growing, cell motility and migration, cytoskeleton rearrangement, and actin polymerization, physiological functions that are intensively impaired during inflammatory conditions, such as the one that occurs in sepsis. In the last few decades, Rho proteins and their downstream pathways have been investigated in sepsis-associated experimental models. The most frequently used experimental design included the exposure to bacterial lipopolysaccharide (LPS), in both in vitro and in vivo approaches, but experiments using the cecal ligation and puncture (CLP) model of sepsis have also been performed. The findings described in this review indicate that Rho proteins, mainly RhoA and Rac1, are associated with the development of crucial sepsis-associated dysfunction in different systems and cells, including the endothelium, vessels, and heart. Notably, the data found in the literature suggest that either the inhibition or activation of Rho proteins and associated pathways might be desirable in sepsis and septic shock, accordingly with the cellular system evaluated. This review included the main findings, relevance, and limitations of the current knowledge connecting Rho proteins and sepsis-associated experimental models.

Dysfunction of Cullin 3 RING E3 ubiquitin ligase causes vasoconstriction and increased sodium reabsorption in diabetes.

Impaired endothelium-mediated vasodilation and/or increased sensitivity to vasoconstrictors lead to vascular smooth muscle cell (VSMC) dysfunction in individuals with diabetes. Diabetic nephropathy is associated with a considerably higher risk of cardiovascular disease and death than their nondiabetic counterparts. We studied the activity of Cullin 3 RING ubiquitin ligase (CRL3) and its substrates in mice using an intraperitoneal injection of streptozotocin (STZ) and db/db mice. The levels of CRL3 adaptors, including Kelch-like 2/3 (KLHL2/3) and Rho-related BTB domain-containing protein 1, were significantly decreased in the aortic tissues and heart of the STZ group, whereas the levels of Cullin 3 (CUL3) and its neddylated derivatives were substantially increased. Decreased KLHL3 expression and significantly increased expression of NEDD8 conjugates were observed in the kidneys of db/db mice. The neddylation inhibitor MLN4924 decreased the degradation of KLHL2/KLHL3 under high-glucose conditions with/without insulin, and transfection with KLHL2 promoted the degradation of its substrates with-no-lysine (WNK) kinases. Increased abundance of WNK3, RhoA/ROCK activity and phosphodiesterase 5 enhanced the sensibility to vasoconstrictors and impaired vasodilation. Moreover, WNK3 localized in VSMCs undergoing cell division, and high-glucose medium increased WNK3 signaling in VSMCs undergoing mitosis, which might explain the increased thickness of aortic tissues in subjects with diabetes. Increases in WNK4 abundance resulted in increased sodium reabsorption in the distal renal tubules. Thus, KLHL2/RhoBTB1/KLHL3 inactivation in the aortic tissues and kidney is a result of excessive activation of neddylation in hyperglycemia and hyperinsulinemia, which affects vascular tone and sodium reabsorption.

Rho signaling inhibition mitigates lung injury via targeting neutrophil recruitment and selectin-AKT signaling.

Neutrophils, the early responders of the immune system, eliminate intruders, but their over-activation can also instigate tissue damage leading to various autoimmune and inflammatory disease conditions. As approaches causing neutropenia are associated with immunodeficiency, targeting aberrant neutrophil infiltration offers an attractive strategy in neutrophil-centered diseases including acute lung injury. Rho GTPase family proteins Rho, Rac and Cdc42 play important role as regulators of chemotaxis in diverse systems. Rho inhibitors protected against lung injuries, while genetic Rho-deficiency exhibited neutrophil hyperactivity and exacerbated lung injury. These differential outcomes might be due to distinct effects on different cell types or activation/ inhibition of specific signaling pathways responsible for neutrophil polarity, migration and functions. In this study, we explored neutrophil centric effects of Rho signaling mitigation. Consistent with previous reports, Rho signaling inhibitor Y-27632 provided protection against acute lung injury, but without regulating LPS mediated systemic increase of neutrophils in the circulation. Interestingly, the adoptive transfer approach identified a specific defect in neutrophil migration capacity after Rho signaling mitigation. These defects were associated with loss of polarity and altered actin dynamics identified using time-lapse in vitro studies. Further analysis revealed a rescue of stimulation-dependent L-selectin shedding on neutrophils with Rho signaling inhibitor. Surprisingly, functional blocking of L-selectin (CD62L) led to defective recruitment of neutrophils into inflamed lungs. Further, single-cell level analyses identified MAPK signaling as downstream mechanism of Rho signaling and L-selectin mediated effects. p-AKT levels were diminished in detergent resistance membrane-associated signalosome upon Rho signaling inhibition and blockade of selectin. Moreover, inhibition of AKT signaling as well as selectin blocking led to defects in neutrophil polarity. Together, this study identified Rho-dependent distinct L-selectin and AKT signaling mediated regulation of neutrophil recruitment to inflamed lung tissue.

Mechanical stiffness augments ligand-dependent progesterone receptor B activation via MEK 1/2 and Rho/ROCK-dependent signaling pathways in uterine fibroid cells.

OBJECTIVE: To test whether mechanical substrate stiffness would influence progesterone receptor B (PRB) signaling in fibroid cells. Uterine fibroids feature an excessive extracellular matrix, increased stiffness, and altered mechanical signaling. Fibroid growth is stimulated by progestins and opposed by anti-progestins, but a functional interaction between progesterone action and mechanical signaling has not been evaluated. DESIGN: Laboratory studies. SETTING: Translational science laboratory. PATIENT(S)/ANIMAL(S): Human fibroid cell lines and patient-matched fibroid and myometrial cell lines. INTERVENTION(S): Progesterone receptor B-dependent reporter assays and messenger RNA quantitation in cells cultured on stiff polystyrene plates (3GPa) or soft silicone plates (930KPa). Pharmacologic inhibitors of extracellular signal-related protein kinase (ERK) kinase 1/2 (MEK 1/2; PD98059), p38 mitogen-activated protein kinase (SB202190), receptor tyrosine kinases (RTKs; nintedanib), RhoA (A13), and Rho-associated coiled-coil kinase (ROCK; Y27632). MAIN OUTCOME MEASURE(S): Progesterone-responsive reporter activation. RESULT(S): Fibroid cells exhibited higher PRB-dependent reporter activity with progesterone (P4) in cells cultured on stiff vs. soft plates. Mechanically induced PRB activation with P4 was decreased 62% by PD98059, 78% by nintedanib, 38% by A13, and 50% by Y27632. Overexpression of the Rho-guanine nucleotide exchange factor (Rho-GEF), AKAP13, significantly increased PRB-dependent reporter activity. Collagen 1 messenger RNA levels were higher in fibroid cells grown on stiff vs. soft plates with P4. CONCLUSION(S): Cells cultured on mechanically stiff substrates had enhanced PRB activation via a mechanism that required MEK 1/2 and AKAP13/RhoA/ROCK signaling pathways. These studies provide a framework to explore the mechanisms by which mechanical stiffness affects progesterone receptor activation.

Propofol relieves inflammation in MIRI rats by inhibiting Rho/Rock signaling pathway.

OBJECTIVE: The aim of this study was to investigate the effects of propofol on myocardial ischemia-reperfusion injury (MIRI) and its mechanism by establishing in vivo rat models. MATERIALS AND METHODS: Sprague-Dawley rats were selected for the construction of MIRI models in vivo. All rats were divided into three groups, including sham operation group (Sham operation), MIRI group and MIRI + propofol group. At 2 h after reperfusion, myocardial tissues and blood samples were collected from rats. The expression levels of serum lactic dehydrogenase (LDH) and creatine kinase-MB (CK-MB), as well as serum interleukin-6 (IL-6), IL-10 and tumor necrosis factor-α (TNF-α), were measured in each group of rats, respectively. Terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate-biotin nick end labeling (TUNEL) assay was employed to detect the apoptosis of myocardial cells. Additionally, the messenger ribonucleic acid (mRNA) and protein expressions of Ras homolog gene family, member A (RhoA) and Rho-associated coiled-coil-containing protein kinase 2 (Rock2) were determined via quantitative reverse transcription-polymerase chain reaction (qRT-PCR) and Western blotting, respectively. RESULTS: (1) The expression levels of serum LDH and CK-MB were significantly lower in MIRI + propofol group than those in MIRI group (p<0.05). (2) In comparison with MIRI group, MIRI + propofol group exhibited significantly reduced serum IL-6 and TNF-α levels (p<0.01) and elevated serum IL-10 level (p<0.01). (3) Compared with MIRI group, the apoptosis of myocardial cells was remarkably reduced in MIRI + propofol group after IRI (p<0.05). (4) The mRNA and protein expressions of RhoA and Rock2 were significantly lower in MIRI + propofol group than those in MIRI group (p<0.05). CONCLUSIONS: Propofol relieves MIRI and inflammation, reduces the level of oxidative stress and represses I/R-induced myocardial cell apoptosis in MIRI rats by inhibiting the activity of the Rho/Rock signaling pathway.

Upregulated neuregulin-1 protects against optic nerve injury by regulating the RhoA/cofilin/F-actin axis.

OBJECTIVE: In recent years, the roles of Neuregulin-1 (NRG-1) in optic nerve injury and retinal cells have been investigated. However, the molecular mechanism by which NRG-1 affects optic nerve injury remains elusive and merits deeper exploration. Hence, this study examined the specific function of NRG-1 in the RhoA/cofilin/F-actin axis in optic nerve injury. METHODS: Retinal cells were isolated and identified for subsequent experimental uses. Reverse transcription quantitative polymerase chain reaction and Western blot assays were performed to measure NRG-1 expression in retinal cells which were cultured under elevated pressure. TUNEL staining was used to detect the cell apoptosis rate, and Western blot assay was performed to detect the expression of related genes. The axon growth was examined by immunofluorescence. The effects of NRG-1 on RhoA activity, cofilin phosphorylation, and F-actin were detected by Western blot assay. In other studies we established a rat model of acute optic nerve injury, and tested for beneficial effects of NRG-1 in vivo. RESULTS: High expression of NRG-1 was evident in the retinal tissues of rats with optic nerve injury. Overexpressing NRG-1 successfully inhibited RhoA activity and the phosphorylation of cofilin and promoted F-actin expression. In cell experiments, overexpressed NRG-1 suppressed the apoptosis of retinal cells and promoted axon growth through the RhoA/cofilin/F-actin axis. In animal experiments, overexpressed NRG-1 relieved retinal injury. CONCLUSION: Our results strongly suggest that overexpressed NRG-1 is highly effective in the protection of normal optic nerve function by suppressing RhoA activity and the phosphorylation of cofilin and rescuing F-actin function.

Bioinformatic analysis of RHO family of GTPases identifies RAC1 pharmacological inhibition as a new therapeutic strategy for hepatocellular carcinoma.

OBJECTIVE: The RHO family of GTPases, particularly RAC1, has been linked with hepatocarcinogenesis, suggesting that their inhibition might be a rational therapeutic approach. We aimed to identify and target deregulated RHO family members in human hepatocellular carcinoma (HCC). DESIGN: We studied expression deregulation, clinical prognosis and transcription programmes relevant to HCC using public datasets. The therapeutic potential of RAC1 inhibitors in HCC was study in vitro and in vivo. RNA-Seq analysis and their correlation with the three different HCC datasets were used to characterise the underlying mechanism on RAC1 inhibition. The therapeutic effect of RAC1 inhibition on liver fibrosis was evaluated. RESULTS: Among the RHO family of GTPases we observed that RAC1 is upregulated, correlates with poor patient survival, and is strongly linked with a prooncogenic transcriptional programme. From a panel of novel RAC1 inhibitors studied, 1D-142 was able to induce apoptosis and cell cycle arrest in HCC cells, displaying a stronger effect in highly proliferative cells. Partial rescue of the RAC1-related oncogenic transcriptional programme was obtained on RAC1 inhibition by 1D-142 in HCC. Most importantly, the RAC1 inhibitor 1D-142 strongly reduce tumour growth and intrahepatic metastasis in HCC mice models. Additionally, 1D-142 decreases hepatic stellate cell activation and exerts an anti-fibrotic effect in vivo. CONCLUSIONS: The bioinformatics analysis of the HCC datasets, allows identifying RAC1 as a new therapeutic target for HCC. The targeted inhibition of RAC1 by 1D-142 resulted in a potent antitumoural effect in highly proliferative HCC established in fibrotic livers.

Inhibition of RhoA Activity Does Not Rescue Synaptic Development Abnormalities and Long-Term Cognitive Impairment After Sevoflurane Exposure.

General anesthetics interfere with dendritic development and synaptogenesis, resulting in cognitive impairment in the developing animals. RhoA signal pathway plays important roles in dendritic development by regulating cytoskeleton protein such as tubulin and actin. However, it's not clear whether RhoA pathway is involved in inhaled general anesthetics sevoflurane-induced synaptic development abnormalities and long-term cognitive dysfunction. Rats at postnatal day 7 (PND7) were injected intraperitoneally with RhoA pathway inhibitor Y27632 or saline 20 min before exposed to 2.8% sevoflurane for 4 h. The apoptosis-related proteins and RhoA/CRMP2 pathway proteins in the hippocampus were measured 6 h after sevoflurane exposure. Cognitive functions were evaluated by the open field test on PND25 rats and contextual fear conditioning test on PND32-33 rats. The dendritic morphology and density of dendritic spines in the pyramidal neurons of hippocampus were determined by Golgi staining and the synaptic plasticity-related proteins were also measured on PND33 rats. Long term potentiation (LTP) from hippocampal slices was recorded on PND34-37 rats. Sevoflurane induced caspase-3 activation, decreased the ratio of Bcl-2/Bax and increased TUNEL-positive neurons in hippocampus of PND7 rats, which were attenuated by inhibition of RhoA. However, sevoflurane had no significant effects on activity of RhoA/CRMP2 pathway. Sevoflurane disturbed dendritic morphogenesis, reduced the number of dendritic spines, decreased proteins expression of PSD-95, drebrin and synaptophysin, inhibited LTP in hippocampal slices and impaired memory ability in the adolescent rats, while inhibition of RhoA activity did not rescue the changes above induced by sevoflurane. RhoA signal pathway did not participate in sevoflurane-induced dendritic and synaptic development abnormalities and cognitive dysfunction in developing rats.

Pleiotropic effects of statins: A focus on cancer.

The statin drugs ('statins') potently inhibit hydroxymethylglutaryl-coenzyme A (HMG-CoA) reductase by competitively blocking the active site of the enzyme. Statins decrease de novo cholesterol biosynthesis and thereby reduce plasma cholesterol levels. Statins exhibit "pleiotropic" properties that are independent of their lipid-lowering effects. For example, preclinical evidence suggests that statins inhibit tumor growth and induce apoptosis in specific cancer cell types. Furthermore, statins show chemo-sensitizing effects by impairing Ras family GTPase signaling. However, whether statins have clinically meaningful anti-cancer effects remains an area of active investigation. Both preclinical and clinical studies on the potential mechanisms of action of statins in several cancers have been reviewed in the literature. Considering the contradictory data on their efficacy, we present an up-to-date summary of the pleiotropic effects of statins in cancer therapy and review their impact on different malignancies. We also discuss the synergistic anti-cancer effects of statins when combined with other more conventional anti-cancer drugs to highlight areas of potential therapeutic development.

RpS13 controls the homeostasis of germline stem cell niche through Rho1-mediated signals in the Drosophila testis.

OBJECTIVES: Stem cell niche regulated the renewal and differentiation of germline stem cells (GSCs) in Drosophila. Previously, we and others identified a series of genes encoding ribosomal proteins that may contribute to the self-renewal and differentiation of GSCs. However, the mechanisms that maintain and differentiate GSCs in their niches were not well understood. MATERIALS AND METHODS: Flies were used to generate tissue-specific gene knockdown. Small interfering RNAs were used to knockdown genes in S2 cells. qRT-PCR was used to examine the relative mRNA expression level. TUNEL staining or flow cytometry assays were used to detect cell survival. Immunofluorescence was used to determine protein localization and expression pattern. RESULTS: Herein, using a genetic manipulation approach, we investigated the role of ribosomal protein S13 (RpS13) in testes and S2 cells. We reported that RpS13 was required for the self-renewal and differentiation of GSCs. We also demonstrated that RpS13 regulated cell proliferation and apoptosis. Mechanistically, we showed that RpS13 regulated the expression of ribosome subunits and could moderate the expression of the Rho1, DE-cad and Arm proteins. Notably, Rho1 imitated the phenotype of RpS13 in both Drosophila testes and S2 cells, and recruited cell adhesions, which was mediated by the DE-cad and Arm proteins. CONCLUSION: These findings uncover a novel mechanism of RpS13 that mediates Rho1 signals in the stem cell niche of the Drosophila testis.

Tanshinone IIA Promotes Axonal Regeneration in Rats with Focal Cerebral Ischemia Through the Inhibition of Nogo-A/NgR1/RhoA/ROCKII/MLC Signaling.

PURPOSE: The aim of this study was to evaluate the neuroprotective effect of tanshinone IIA (TSA) on focal cerebral ischemia in rats and to investigate whether it was associated with Nogo-A/NgR1/RhoA/Rho-associated protein kinase 2 (ROCKII)/myosin light chain (MLC) signaling. METHODS: In this study, focal cerebral ischemia animal model was used. Neurological deficit scores and infarction volume were investigated to evaluate the neuroprotection of TSA. Hematoxylin-eosin staining, Nissl staining, and immunofluorescence staining were conducted to detect ischemic changes in brain tissue and changes in neurofilament protein 200 (NF200) and growth-associated protein-43 (GAP-43) expression, respectively. Western blotting and qRT-PCR analyses were used to detect the expression levels of NF200, GAP-43 and Nogo-A/NgR1/RhoA/ROCKII/MLC pathway-related signaling molecules. RESULTS: TSA treatment can improve the survival rate of rats, reduce the neurological score and infarct volume, and reduce neuron damage. In addition, TSA also increased axon length and enhanced expression of NF200 and GAP-43. Importantly, TSA significantly attenuated the expression of Nogo-A, NgR1, RhoA, ROCKII, and p-MLC, and thus inhibiting the activation of this signaling pathway. CONCLUSION: TSA promoted axonal regeneration by inhibiting the Nogo-A/NgR1/RhoA/ROCKII/MLC signaling pathway, thereby exerting neuroprotective effects in cerebral ischemia rats, which provided support for the clinical application of TSA in stroke treatment.

Oxycodone inhibits myocardial cell apoptosis after myocardial ischemia-reperfusion injury in rats via RhoA/ROCK1 signaling pathway.

OBJECTIVE: The purpose of this study was to investigate the effect of oxycodone on myocardial ischemia-reperfusion injury in rats through the Ras homolog gene family member A (RhoA)/Rho-associated coiled-coil containing protein kinase 1 (ROCK1) signaling pathway. MATERIALS AND METHODS: A total of 48 Sprague-Dawley (SD) rats were randomly divided into sham operation group, model group, oxycodone group, and inhibitor group, with 12 rats in each group. The rats in the sham operation group only underwent thoracotomy without ischemia-reperfusion injury, those in the model group were used to prepare the myocardial ischemia-reperfusion model with normal saline intervention, those in the oxycodone group were used to prepare the myocardial ischemia-reperfusion model with oxycodone intervention, and those in the inhibitor group were utilized to prepare the myocardial ischemia-reperfusion model with AG490 intervention. Then, the expressions of B-cell lymphoma 2 (Bcl-2) and Bcl-2-associated X protein (BAX) were detected by immunohistochemistry, the relative protein expressions of RhoA and ROCK1 were examined via Western blotting, and the messenger ribonucleic acid (mRNA) expressions of Bcl-2 and BAX were measured by quantitative Polymerase Chain Reaction (qPCR). Thereafter, terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) was adopted for apoptosis detection, and the levels of creatine kinase-muscle/brain (CK-MB), and cardiac Troponin I (cTnI) in serum were detected using an automatic biochemical analyzer. RESULTS: Immunohistochemistry results showed that compared with those in the sham operation group, the positive expression of BAX was remarkably increased (p<0.05), while that of Bcl-2 was significantly decreased (p<0.05) in the model group, oxycodone group, and inhibitor group. Compared with the model group, oxycodone group and inhibitor group had an evidently reduced positive expression of BAX (p<0.05) and an evidently raised positive expression of Bcl-2 (p<0.05). No differences were found in the positive expressions of BAX and Bcl-2 between oxycodone group and inhibitor group (p>0.05). According to Western blotting results, the relative protein expressions of RhoA and ROCK1 in the model group, oxycodone group, and inhibitor group were notably increased compared with those in the sham operation group (p<0.05). In comparison with those in the model group, the relative protein expressions of RhoA and ROCK1 in the oxycodone group and inhibitor group were predominantly reduced (p<0.05). There were no differences in the relative protein expressions of RhoA and ROCK1 between oxycodone group and inhibitor group (p>0.05). Moreover, it was discovered from qRT-PCR results that compared with those in the sham operation group, the mRNA expression of BAX was markedly raised (p<0.05), whereas that of Bcl-2 was decreased predominantly (p<0.05) in the model group, oxycodone group, and inhibitor group. Compared with the model group, oxycodone group, and inhibitor group had an evidently reduced mRNA expression of BAX (p<0.05) and a significantly raised mRNA expression of Bcl-2 (p<0.05). No differences were found in the mRNA expressions of BAX and Bcl-2 between oxycodone group and inhibitor group (p>0.05). In addition, TUNEL assay results manifested that compared with sham operation group, model group, oxycodone group, and inhibitor group had a markedly elevated apoptosis rate (p<0.05). In comparison with the model group, the apoptosis rate in oxycodone group and inhibitor group was remarkably reduced (p<0.05). There was no difference in the apoptosis rate between oxycodone group and inhibitor group (p>0.05). According to biochemical analysis results, the serum levels of CK-MB and cTnI in model group, oxycodone group, and inhibitor group were significantly increased compared with those in the sham operation group, with statistically significant differences (p<0.05). The levels of serum CK-MB and cTnI in the oxycodone group and inhibitor group were substantially lowered in comparison with those in the model group, displaying statistically significant differences (p<0.05). Besides, the levels of serum CK-MB and cTnI in the oxycodone group were not different from those in the inhibitor group (p>0.05). CONCLUSIONS: Oxycodone inhibits myocardial cell apoptosis after myocardial ischemia-reperfusion injury by suppressing the RhoA/ROCK1 signaling pathway.

Inactivation of Rho GTPases by Burkholderia cenocepacia Induces a WASH-Mediated Actin Polymerization that Delays Phagosome Maturation.

Burkholderia cenocepacia is an opportunistic bacterial pathogen that causes severe pulmonary infections in cystic fibrosis and chronic granulomatous disease patients. B. cenocepacia can survive inside infected macrophages within the B. cenocepacia-containing vacuole (BcCV) and to elicit a severe inflammatory response. By inactivating the host macrophage Rho GTPases, the bacterial effector TecA causes depolymerization of the cortical actin cytoskeleton. In this study, we find that B. cenocepacia induces the formation of large cytosolic F-actin clusters in infected macrophages. Cluster formation requires the nucleation-promoting factor WASH, the Arp2/3 complex, and TecA. Inactivation of Rho GTPases by bacterial toxins is necessary and sufficient to induce the formation of the cytosolic actin clusters. By hijacking WASH and Arp2/3 activity, B. cenocepacia disrupts interactions with the endolysosomal system, thereby delaying the maturation of the BcCV.

The Histone Methyltransferase G9a Controls Axon Growth by Targeting the RhoA Signaling Pathway.

The generation of axonal and dendritic domains is critical for brain circuitry assembly and physiology. Negative players, such as the RhoA-Rho coiled-coil-associated protein kinase (ROCK) signaling pathway, restrain axon development and polarization. Surprisingly, the genetic control of neuronal polarity has remained largely unexplored. Here, we report that, in primary cultured neurons, expression of the histone methyltransferase G9a and nuclear translocation of its major splicing isoform (G9a/E10+) peak at the time of axon formation. RNAi suppression of G9a/E10+ or pharmacological blockade of G9a constrains neuronal migration, axon initiation, and the establishment of neuronal polarity in situ and in vitro. Inhibition of G9a function upregulates RhoA-ROCK activity by increasing the expression of Lfc, a guanine nucleotide exchange factor (GEF) for RhoA. Together, these results identify G9a as a player in neuronal polarization.

Sanggenon C Ameliorates Cerebral Ischemia-Reperfusion Injury by Inhibiting Inflammation and Oxidative Stress through Regulating RhoA-ROCK Signaling.

Sanggenon C (SC), a natural flavonoid extracted from Cortex Mori (Sang Bai Pi), is reported to possess anti-inflammatory and antioxidant properties in hypoxia. The present study aimed to investigate the therapeutic potential and the underlying mechanisms of SC in cerebral ischemia-reperfusion (I/R) injury. A rat model of reversible middle cerebral artery occlusion (MCAO) was used to induce cerebral I/R injury in vivo, and SC was administrated intragastrically. Brain injuries were evaluated using Bederson scores, brain water content, and 2, 3, 5-triphenyltetrazolium chloride (TTC) staining. The levels of inflammatory factors and oxidative stress were examined using corresponding kits. Cell apoptosis was evaluated by TUNEL. Moreover, the expressions of apoptosis-related and RhoA/ROCK signaling-related proteins were detected through western blotting. In vitro, RhoA was overexpressed in oxygen-glucose deprivation and reperfusion (OGD/R)-induced PC12 cells to confirm the contribution of RhoA-ROCK signaling inhibition by SC to the neuroprotective effects post OGD/R. Pretreatment with SC significantly ameliorated the neurologic impairment, brain edema, and cerebral infarction post MCAO-reperfusion, associated with reductions of inflammation, oxidative stress, and cell apoptosis in the brain. Furthermore, SC remarkably downregulated the expression of RhoA/ROCK signaling-related proteins post MCAO-reperfusion in rats, while overexpression of RhoA reversed the beneficial effects of SC on protecting against inflammation and oxidative stress in OGD/R-induced PC12 cells. Taken together, these findings demonstrated that SC exerts neuroprotective effects after cerebral I/R injury via inhibiting inflammation and oxidative stress through regulating RhoA-ROCK signaling, suggesting a therapeutic potential of SC in cerebral I/R injury.

Atorvastatin alleviates left ventricular remodeling in isoproterenol-induced chronic heart failure in rats by regulating the RhoA/Rho kinase signaling pathway.

BACKGROUND: Chronic heart failure (CHF) is characterized by left ventricular dysfunction and altered autonomic control of cardiac function. This study aimed to investigate the effects of atorvastatin on left ventricular remodeling (LVR) and cardiac function in rats with isoproterenol-induced CHF and the possible mechanism. METHODS: An isoproterenol-induced CHF model was established in rata, which were subsequently treated with atorvastatin. Echocardiography, hemodynamic, and left ventricular mass indexes were assessed. The mRNA expression of RhoA, Rho kinase, and endothelial nitric oxide synthase (eNOS) was determined by RT-qPCR. The protein expression of myosin-binding subunit (MBS), MBS-P, eNOS, phosphorylated-eNOS, RhoA, and Rho kinase was measured by Western blot analysis. The relative activity of NADPH oxidase, ROS, and NO was assessed by ELISA. RESULTS: Isoproterenol-induced CHF rats treated with atorvastatin exhibited decreased left ventricular end-systolic dimension, left ventricular end-diastolic dimension, left ventricular end-diastolic pressure, left ventricular mass index, maximum fall rate of change in left ventricular pressure, heart rate (p < 0.001), expression of RhoA, Rho kinase, MBS and MBS-P (p < 0.01), and relative activity of NADPH oxidase, ROS and NO (p < 0.05) and increased left ventricular short axis fractional shortening, left ventricular end-systolic pressure, maximum rise rate of change in left ventricular pressure (p < 0.001) and expression of eNOS, and phosphorylated-eNOS ser1177 (all p < 0.05) compared with those of rats with isoproterenol-induced CHF. CONCLUSION: We demonstrated that atorvastatin inhibits LVR and improves cardiac function in rats with isoproterenol-induced CHF through inhibition of the RhoA/Rho kinase signaling pathway.

The Rho-guanine nucleotide exchange factor Solo decelerates collective cell migration by modulating the Rho-ROCK pathway and keratin networks.

Collective cell migration plays crucial roles in tissue remodeling, wound healing, and cancer cell invasion. However, its underlying mechanism remains unknown. Previously, we showed that the RhoA-targeting guanine nucleotide exchange factor Solo (ARHGEF40) is required for tensile force-induced RhoA activation and proper organization of keratin-8/keratin-18 (K8/K18) networks. Here, we demonstrate that Solo knockdown significantly increases the rate at which Madin-Darby canine kidney cells collectively migrate on collagen gels. However, it has no apparent effect on the migratory speed of solitary cultured cells. Therefore, Solo decelerates collective cell migration. Moreover, Solo localized to the anteroposterior regions of cell-cell contact sites in collectively migrating cells and was required for the local accumulation of K8/K18 filaments in the forward areas of the cells. Partial Rho-associated protein kinase (ROCK) inhibition or K18 or plakoglobin knockdown also increased collective cell migration velocity. These results suggest that Solo acts as a brake for collective cell migration by generating pullback force at cell-cell contact sites via the RhoA-ROCK pathway. It may also promote the formation of desmosomal cell-cell junctions related to K8/K18 filaments and plakoglobin.

Miro1 Marks Parkinson's Disease Subset and Miro1 Reducer Rescues Neuron Loss in Parkinson's Models.

The identification of molecular targets and pharmacodynamic markers for Parkinson's disease (PD) will empower more effective clinical management and experimental therapies. Miro1 is localized on the mitochondrial surface and mediates mitochondrial motility. Miro1 is removed from depolarized mitochondria to facilitate their clearance via mitophagy. Here, we explore the clinical utility of Miro1 for detecting PD and for gauging potential treatments. We measure the Miro1 response to mitochondrial depolarization using biochemical assays in skin fibroblasts from a broad spectrum of PD patients and discover that more than 94% of the patients' fibroblast cell lines fail to remove Miro1 following depolarization. We identify a small molecule that can repair this defect of Miro1 in PD fibroblasts. Treating patient-derived neurons and fly models with this compound rescues the locomotor deficits and dopaminergic neurodegeneration. Our results indicate that tracking this Miro1 marker and engaging in Miro1-based therapies could open new avenues to personalized medicine.

The Effect of Ras Homolog C/Rho-Associated Coiled-Protein Kinase (Rho/ROCK) Signaling Pathways on Proliferation and Apoptosis of Human Myeloma Cells.

BACKGROUND The aim of this study was to explore the impact of Ras homolog C/Rho-associated coiled-protein kinase (Rho/ROCK) signaling pathways intervention on biological characteristics of the human multiple myeloma cell lines RPMI-8226 and U266 cells, and to investigate the expression of RhoC, ROCK1, and ROCK2 in RPMI-8226 and U266 cells. MATERIAL AND METHODS RPMI8226 and U266 cell lines were treated by 5-aza-2-deoxycytidine (5-Aza-Dc), trichostatin A (TSA), RhoA inhibitor CCG-1423, Rac1 inhibitor NSC23766, and ROCK inhibitor fasudil. Cell proliferation was examined by Cell Counting Kit-8 (CCK-8) assay and clone formation. Cell apoptosis was examined by flow cytometry and TUNEL assay. The mRNA and protein expressions of RhoC, ROCK1, and ROCK2 were detected by quantitative reverse transcription-polymerase chain reaction (qRT-PCR) and western blot, respectively. RESULTS CCG-1423, NSC23766, and fasudil could significantly inhibit the proliferation of RPMI8226 and U266 cells. The inhibitory effect was dose- and time-dependent within a certain concentration range (P<0.05). After treatment with CCG-1423, NSC23766, and fasudil for 24 hours, the apoptosis rates of RPMI8226 and U266 cells were significantly higher than those of the control group, which were dose-dependent (P<0.05). Compared with the control group, the mRNA and protein expressions of RhoC, ROCK1, and ROCK2 in RPMI8226 and U266 cells were significantly decreased with single 5-Aza-Dc or TSA treatment. However, the effects were obviously stronger after combined treatment of 5-Aza-CdR and TSA (P<0.05). CONCLUSIONS We found that 5-Aza-Dc and TSA can effectively decrease the mRNA and protein expressions of RhoC, ROCK1, and ROCK2. Furthermore, Rho and ROCK inhibitors significantly inhibit cell growth and induce cell apoptosis in the human multiple myeloma cell lines RPMI-8226 and U266.