RhoA/ROCK Signaling Regulates TGF-β1-Induced Fibrotic Effects in Human Pterygium Fibroblasts through MRTF-A

PURPOSE

The overexpression of transforming growth factor-beta1 (TGF-β1) after surgical excision often leads to excessive fibrosis, indicating the recurrence of pterygium. The aims of the present in vitro study were to investigate the role of RhoA/ROCK signaling in regulating fibrotic effects of primary human pterygium fibroblasts (HPFs), as well as to explore the possible mechanisms of these effects.

METHODS

Pterygium samples were obtained from surgery, and profibrotic activation was induced by TGF-β1. Cell proliferation was detected by CCK-8 assay; cell migration was detected by wound healing assay; quantitative real-time PCR and Western blot were used to detect the effects of TGF-β1 and the role of RhoA/ROCK signaling in the synthesis of alpha-smooth muscle actin (a-SMA), type I and III collagen (COL1 and COL3), and matrix metalloproteinase-9 (MMP9) in HPFs. The changes of signaling pathways were detected by Western blot; and pharmaceutical inhibition of RhoA/ROCK signaling and its downstream MRFT-A/SRF transcription pathway were used to assess their possible mechanism in HPFs fibrosis.

RESULTS

ROCK inhibitor Y-27632 decreased TGF-β1-induced cell proliferation and migration, reduced the TGF-β1-induced expression of profibrotic markers in HPFs, and suppressed TGF-β1-induced nuclear accumulation of Myocardin-related transcription factor A (MRTF-A) as well as accompanied elevation of F/G-actin ratio in HPFs. MRTF-A/Serum response factor (SRF) inhibitor CCG-100602 attenuated the TGF-β1-induced α-SMA expression and reduced myofibroblast activation in HPFs.

CONCLUSIONS

RhoA/ROCK signaling played a pivotal role in TGF-β1-induced fibrosis and myofibroblast activation in HPFs at least in part by inactivating the downstream MRTF-A/SRF transcriptional pathway.

WITHDRAWN: Anti-inflammatory role and mechanism of microRNA-92b-3p in the progression of hypoxic pulmonary hypertension

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Protection of ripasudil, a Rho kinase inhibitor, in lipopolysaccharides-induced acute pneumonia in mice

Pneumonia is a major cause of morbidity and mortality of infectious diseases, especially in children. Ripasudil (K-115), a selective ROCK inhibitor, is a promising emerging drug against glaucoma, and reported to have anti-inflammatory activity. However, the anti-inflammatory effect of ripasudil still remains unclear in pneumonia. The goal of this study is to investigate the role and the underlying mechanism of ripasudil in pneumonia. BALB/c mice were used to establish an acute pneumonia model of mice by injection of lipopolysaccharide (LPS) intraperitoneally. Ripasudil (0.5 mg, 1 mg, 2 mg) was administrated 1 h before the induction of LPS. The histoligical change of lung tissue was evaluated by hematoxylin-eosin staining and lung wet/dry ratio. Inflammatory cytokines secretion, oxidant-antioxidant factors levels were measured. Cell apoptosis was examined using TNUEL assay. Western blot and qRT-PCR was used to determine gene expressions. Results showed that ripasudil significantly attenuated LPS-induced histological changes, reduced the production of pro-inflammatory cytokines, and alleviated LPS-induced oxidative stress in mice. LPS-induced cell apoptosis and associated protein expression changes were attenuated by ripasudil. Besides, ripasudil reduced the expression of RhoA, and decreased the activity of RhoA/ROCK signaling. Finally, the level of RhoA and eNOS from pneumonia patients exhibited negatively correlated, whereas the level of RhoA was higher while eNOS level was lower than that in the healthy control. The results of the present study indicate that ripasudil attenuate LPS-induced pneumonia in BALB/c mice by ameliorating inflammation, oxidative stress and apoptosis through inhibiting RhoA/ROCK signaling pathway. Ripasudil might be a novel and effective drug for the treatment of pneumonia.

[Effect of Different Stimulating Strength of Electroacupuncture on Gastrointestinal Motility and RhoA/ROCK Signaling in Gastric Antral Smooth Muscle in Diabetic Gastroparesis Rats]

OBJECTIVE

To observe the effect of different strength of electroacupuncture (EA) stimulation on gastrointestinal motility and Ras homolog gene family member (RhoA)/Rho associated coiled-coil forming protein kinase (ROCK) signaling in diabetic gastroparesis (DGP) rats, so as to reveal the underlying mechanisms of EA for improving DGP.

METHODS

Sixty SD rats were randomly and equally divided into blank control, DGP model, weak EA, medium EA, and strong EA groups (n＝12 rats in each). The DGP model was established by intraperitoneal injection of streptozotocin (STZ, 55 mmol/kg, 2%) and high-sugar and high-fat fodder feeding for 8 weeks. EA (0.12, 0.24, 0.36 mA, 20 Hz/100 Hz) was applied to "Zusanli" (ST 36), "Sanyinjiao" (SP 6) and "Liangmen" (ST 21) for 20 min, once daily for 15 successive days. Blood glucose levels were measured weekly with blood glucose meter and blood glucose test paper. Fecal phenol red excretion method was used to display gastric emptying and small intestinal propulsion function. The expression of RhoA protein in the gastric antral smooth muscle tissue was detected by immunohistochemistry and Western blot (WB), separately, and that of ROCK, myosin phosphatase target subunit 1 (MYPT 1) and phosphorylated (p)-MYPT 1 proteins in gastric antrum detected by WB.

RESULTS

Compared with the blank control group, the gastric emptying rate and small intestine propulsion rate of the model group were significantly decreased (P<0.05), and the blood glucose level was remarkably increased (P<0.05). Moreover, the expression levels of RhoA, ROCK, MYPT 1 and p-MYPT 1 proteins in the gastric antrum were significantly down-regulated relevant to the control group (P<0.05). After administration of EA, the decreased gastric emptying rate and intestinal propulsion rate, and the down-regulated expression of RhoA, ROCK, MYPT 1 and p-MYPT 1 proteins were significantly increased in the strong, medium and weak EA stimulation groups (P<0.05). Comparison among the 3 EA groups showed that the strong stimulation was significantly superior to weak stimulation in up-regulating the expression of RhoA, ROCK, MYPT 1 and p-MYPT 1 proteins, and obviously superior to the medium stimulation in up-regulating RhoA and MYPT 1 protein levels (P<0.05), while the medium stimulation was significantly stronger than the weak stimulation in up-regulating the expression of ROCK, MYPT 1 and p-MYPT 1 proteins (P<0.05). There were no significant differences among the 3 EA groups in up-regulating the gastric emptying rate and small intestinal propulsion rate, and between the strong stimulation and medium stimulation in the expression levels of ROCK and p-MYPT 1 proteins (P>0.05).

CONCLUSION

Electroacupuncture stimulation of ST 36-SP 6-ST 21 at 0.12, 0.24 and 0.36 mA can promote the gastrointestinal motility in DGP rats, which may be associated with its effects in enhancing RhoA/ROCK signaling in the gastric antral smooth muscle at different degrees.

Involvement of RhoA/ROCK Signaling in Aβ-Induced Chemotaxis, Cytotoxicity and Inflammatory Response of Microglial BV2 Cells

Reactive microglia clustering around amyloid plaques in brain is a histopathological feature of Alzheimer's disease (AD) and reflects the contribution of neuroinflammation in AD pathogenesis. β-Amyloid peptide (Aβ) has been shown to induce a range of microglial responses including chemotaxis, cytotoxicity and inflammation, but the underlying mechanism is poorly understood. Considering the fundamental role of RhoA/ROCK signaling in cell migration and its broad implication in AD and neuroinflammation, we hypothesized that RhoA/ROCK signaling might be involved in Aβ-induced microglial responses. From in vivo mouse models including APP/PS1 transgene and fibrillar Aβ stereotactic injection, we observed the elevated expression level of RhoA in reactive microglia. Through a series in vitro cell migration, cytotoxicity and biochemistry assays, we found that RhoA/ROCK signaling plays an essential role in Aβ-induced responses of microglial BV2 cells. Small molecular agents Fasudil and Y27632 showed prominent beneficial effects, which implies the therapeutic potential of RhoA/ROCK signaling inhibitors in AD treatment.

Interplay of cell-cell contacts and RhoA/MRTF-A signaling regulates cardiomyocyte identity

Cell-cell and cell-matrix interactions guide organ development and homeostasis by controlling lineage specification and maintenance, but the underlying molecular principles are largely unknown. Here, we show that in human developing cardiomyocytes cell-cell contacts at the intercalated disk connect to remodeling of the actin cytoskeleton by regulating the RhoA-ROCK signaling to maintain an active MRTF/SRF transcriptional program essential for cardiomyocyte identity. Genetic perturbation of this mechanosensory pathway activates an ectopic fat gene program during cardiomyocyte differentiation, which ultimately primes the cells to switch to the brown/beige adipocyte lineage in response to adipogenesis-inducing signals. We also demonstrate by in vivo fate mapping and clonal analysis of cardiac progenitors that cardiac fat and a subset of cardiac muscle arise from a common precursor expressing Isl1 and Wt1 during heart development, suggesting related mechanisms of determination between the two lineages.

The crosstalk between breast carcinoma-associated fibroblasts and cancer cells promotes RhoA-dependent invasion via IGF-1 and PAI-1

Carcinoma-associated fibroblasts (CAFs) can remodel the extracellular matrix to promote cancer cell invasion, but the paracrine signaling between CAFs and cancer cells that regulates tumor cell migration remains to be identified. To determine how the interaction between CAFs and cancer cells modulates the invasiveness of cancer cells, we developed a 3-dimensional co-culture model composed of breast cancer (BC) MDA-MB-231 cell spheroids embedded in a collagen gel with and without CAFs. We found that the crosstalk between CAFs and cancer cells promotes invasion by stimulating the scattering of MDA-MB-231 cells, which was dependent on RhoA/ROCK/phospho MLC signaling in cancer cells but independent of RhoA in CAFs. The activation of RhoA/ROCK in cancer cells activates MLC and increases migration, while the genetic-down-regulation of RhoA and pharmacological inhibition of ROCK reduced cell scattering and invasion. Two distinct mechanisms induced the activation of the RhoA/ROCK pathway in MDA-MB-231 cells, the secretion of IGF-1 by CAFs and the upregulation of PAI-1 in cancer cells. In an orthotopic model of BC, IGF-1R inhibition decreased the incidence of lung metastasis, while Y27632-inhibition of ROCK enhanced the lung metastasis burden, which was associated with an increased recruitment of CAFs and expression of PAI-1. Thus the crosstalk between CAFs and BC cells increases the secretion of IGF-1 in CAFs and PAI-1 activity in cancer cells. Both IGF1 and PAI-1 activate RhoA/ROCK signaling in cancer cells, which increases cell scattering and invasion.

Restoration of uridine 5'-triphosphate-suppressed delayed rectifying K+ currents by an NO activator KMUP-1 involves RhoA/Rho kinase signaling in pulmonary artery smooth muscle cells

We have demonstrated that KMUP-1 (7-[2-[4-(2-chlorobenzene)piperazinyl]ethyl]-1,3-dimethylxanthine) blunts monocrotaline-induced pulmonary arterial hypertension by altering Ca²⁺ sensitivity, K⁺-channel function, endothelial nitric oxide synthase activity, and RhoA/Rho kinase (ROCK) expression. This study further investigated whether KMUP-1 impedes uridine 5'-triphosphate (UTP)-inhibited delayed rectifying K⁺ (K_DR) current in rat pulmonary arteries involved the RhoA/ROCK signaling. Pulmonary artery smooth muscle cells (PASMCs) were enzymatically dissociated from rat pulmonary arteries. KMUP-1 (30μM) attenuated UTP (30μM)-mediated membrane depolarization and abolished UTP-enhanced cytosolic Ca²⁺ concentration. Whole-cell patch-clamp electrophysiology was used to monitor K_DR currents. A voltage-dependent K_DR current was isolated and shown to consist of a 4-aminopyridine (5mM)-sensitive component and an insensitive component. The 4-aminopyridine sensitive K_DR current was suppressed by UTP (30μM). The ROCK inhibitor Y27632 (30μM) abolished the ability of UTP to inhibit the K_DR current. Like Y27632, KMUP-1 (30μM) similarly abolished UTP-inhibited K_DR currents. Superfused protein kinase A and protein kinase G inhibitors (KT5720, 300nM and KT5823, 300nM) did not affect UTP-inhibited K_DR currents, but the currents were restored by adding KMUP-1 (30μM) to the superfusate. KMUP-1 reversal of K_DR current inhibition by UTP predominantly involves the ROCK inhibition. The results indicate that the RhoA/ROCK signaling pathway plays a key role in eliciting PASMCs depolarization caused by UTP, which would result in pulmonary artery constriction. KMUP-1 blocks UTP-mediated PASMCs depolarization, suggesting that it would prevent abnormal pulmonary vasoconstriction.