MiRNA-190 exerts neuroprotective effects against ischemic stroke through Rho/Rho-kinase pathway

Ischemic stroke is an urgent public health concern and one of the major causes of deaths and disabilities over the world. MicroRNA (miRNA) has become a key mediator of cerebral ischemia-reperfusion (I/R) injuries. However, whether miR-190 is involved in cerebral I/R-induced neuronal damage remains unknown. This study was to investigate the role of miR-190 in the brain I/R injury. We divided the rats into sham, I/R, control, and miR-190-mim (miR-190 mimics) groups. Quantitative real-time polymerase chain reaction (qRT-PCR), Nissl staining, flow cytometry, and western blot were conducted to examine the expression of miR-190 and cell apoptosis in different groups. The results showed that the expression of miR-190 was greatly decreased in rats suffering with I/R. Overexpression of miR-190 significantly reduced the increased neurological scores, brain water contents, infarct volumes, and neuronal apoptosis in rats suffering with I/R. In addition, we found that the expression of RhoA and Rho kinase was greatly elevated in rats suffering with I/R. Bioinformatics analysis indicated that Rho was a target of miR-190. Moreover, overexpression of miR-190 significantly downregulated the increased mRNA and protein expression of Rho/Rho kinase and cell apoptosis, while inhibition of miR-190 further upregulated the increased mRNA and protein expression of Rho/Rho kinase and cell apoptosis in rats suffering with I/R. Furthermore, knockdown of Rho significantly downregulated the increased mRNA and protein expression of Rho/Rho kinase and cell apoptosis, while these effects were inhibited by miR-190 inhibitors in rats suffering with I/R. These results indicate that miR-190 confers protection against brain I/R damage by modulating Rho/Rho-kinase signaling.

TRPV4 deletion protects heart from myocardial infarction-induced adverse remodeling via modulation of cardiac fibroblast differentiation

Cardiac fibrosis caused by adverse cardiac remodeling following myocardial infarction can eventually lead to heart failure. Although the role of soluble factors such as TGF-β is well studied in cardiac fibrosis following myocardial injury, the physiological role of mechanotransduction is not fully understood. Here, we investigated the molecular mechanism and functional role of TRPV4 mechanotransduction in cardiac fibrosis. TRPV4KO mice, 8 weeks following myocardial infarction (MI), exhibited preserved cardiac function compared to WT mice. Histological analysis demonstrated reduced cardiac fibrosis in TRPV4KO mice. We found that WT CF exhibited hypotonicity-induced calcium influx and extracellular matrix (ECM)-stiffness-dependent differentiation in response to TGF-β1. In contrast, TRPV4KO CF did not display hypotonicity-induced calcium influx and failed to differentiate on high-stiffness ECM gels even in the presence of saturating amounts of TGF-β1. Mechanistically, TRPV4 mediated cardiac fibrotic gene promoter activity and fibroblast differentiation through the activation of the Rho/Rho kinase pathway and the mechanosensitive transcription factor MRTF-A. Our findings suggest that genetic deletion of TRPV4 channels protects heart from adverse cardiac remodeling following MI by modulating Rho/MRTF-A pathway-mediated cardiac fibroblast differentiation and cardiac fibrosis.

TRPV4 channels regulate tumor angiogenesis via modulation of Rho/Rho kinase pathway

Targeting angiogenesis is considered a promising therapy for cancer. Besides curtailing soluble factor mediated tumor angiogenesis, understanding the unexplored regulation of angiogenesis by mechanical cues may lead to the identification of novel therapeutic targets. We have recently shown that expression and activity of mechanosensitive ion channel transient receptor potential vanilloid 4 (TRPV4) is suppressed in tumor endothelial cells and restoring TRPV4 expression or activation induces vascular normalization and improves cancer therapy. However, the molecular mechanism(s) by which TRPV4 modulates angiogenesis are still in their infancy. To explore how TRPV4 regulates angiogenesis, we have employed TRPV4 null endothelial cells (TRPV4KO EC) and TRPV4KO mice. We found that absence of TRPV4 (TRPV4KO EC) resulted in a significant increase in proliferation, migration, and abnormal tube formation in vitro when compared to WT EC. Concomitantly, sprouting angiogenesis ex vivo and vascular growth in vivo was enhanced in TRPV4KO mice. Mechanistically, we observed that loss of TRPV4 leads to a significant increase in basal Rho activity in TRPV4KO EC that corresponded to their aberrant mechanosensitivity on varying stiffness ECM gels. Importantly, pharmacological inhibition of the Rho/Rho kinase pathway by Y-27632 normalized abnormal mechanosensitivity and angiogenesis exhibited by TRPV4KO EC in vitro. Finally, Y-27632 treatment increased pericyte coverage and in conjunction with Cisplatin, significantly reduced tumor growth in TRPV4KO mice. Taken together, these data suggest that TRPV4 regulates angiogenesis endogenously via modulation of EC mechanosensitivity through the Rho/Rho kinase pathway and can serve as a potential therapeutic target for cancer therapy.

Role of Rho kinase signal pathway in inflammatory bowel disease

Inflammatory Bowel Disease (IBD) is nonspecific inflammation in the intestinal track, including Ulcerative Colitis (UC) and Crohn's disease (CD). The incidence of IBD has increased significantly, with its numerous rising up to five million globally, more than 1,700,000 in China. Pathological character of IBD is the inflammation of intestinal mucosa and intestinal fibrosis. Although the pathogenesis of the disease has not yet been fully clarified, some evidence suggests that excessive intestinal inflammation reaction, intestinal barrier impairment and abnormal immune response can initiate IBD. As research continues, some of them have provided new insights toward understanding of Rho kinase signal pathway function at the occurrence and development of IBD. This review aims to summarize the general principles of Rho kinase signal pathway in the pathological procedure of IBD.