Fasudil ameliorates endothelial dysfunction in streptozotocin-induced diabetic rats: a possible role of Rho kinase

RhoA/ROCK Signaling Is Involved in Pathological Retinal Neovascularization

OBJECTIVE

The aim of the study was to evaluate the effect of the RhoA/ROCK inhibitor Fasudil on retinal neovascularization (NV) in vivo and angiogenesis in vitro.

METHODS

C57BL/6 was used to establish an OIR model. First, RhoA/ROCK expression was first examined and compared between OIR and healthy controls. Then, we evaluated the effect of Fasudil on pathological retinal NV. Whole-mount retinal staining was performed. The percentage of NV area, the number of neovascular tufts (NVT), and branch points (BP) were quantified. Finally, human umbilical vein endothelial cells (HUVECs) were used to investigate the effect of Fasudil on angiogenesis.

RESULTS

Real-time PCR and Western blotting showed that ROCK expression in retinal tissue was statistically upregulated in OIR. Furthermore, we found that Fasudil attenuated the percentage of NV area, the number of NVT, and BP significantly. In addition, Fasudil could suppress the proliferation and migration of HUVECs induced by VEGF.

CONCLUSIONS

RhoA/ROCK might be involved in the pathogenesis of OIR. And its inhibitor Fasudil could suppress retinal NV in vivo and angiogenesis in vitro. Fasudil may be a potential treatment strategy for retinal vascular diseases.

Neoprzewaquinone A Inhibits Breast Cancer Cell Migration and Promotes Smooth Muscle Relaxation by Targeting PIM1 to Block ROCK2/STAT3 Pathway

Salvia miltiorrhiza Bunge (Danshen) has been widely used to treat cancer and cardiovascular diseases in Chinese traditional medicine. Here, we found that Neoprzewaquinone A (NEO), an active component of S. miltiorrhiza, selectively inhibits PIM1. We showed that NEO potently inhibits PIM1 kinase at nanomolar concentrations and significantly suppresses the growth, migration, and Epithelial-Mesenchymal Transition (EMT) in the triple-negative breast cancer cell line, MDA-MB-231 in vitro. Molecular docking simulations revealed that NEO enters the PIM1 pocket, thereby triggering multiple interaction effects. Western blot analysis revealed that both NEO and SGI-1776 (a specific PIM1 inhibitor), inhibited ROCK2/STAT3 signaling in MDA-MB-231 cells, indicating that PIM1 kinase modulates cell migration and EMT via ROCK2 signaling. Recent studies indicated that ROCK2 plays a key role in smooth muscle contraction, and that ROCK2 inhibitors effectively control the symptoms of high intraocular pressure (IOP) in glaucoma patients. Here, we showed that NEO and SGI-1776 significantly reduce IOP in normal rabbits and relax pre-restrained thoracic aortic rings in rats. Taken together, our findings indicated that NEO inhibits TNBC cell migration and relaxes smooth muscles mainly by targeting PIM1 and inhibiting ROCK2/STAT3 signaling, and that PIM1 may be an effective target for IOP and other circulatory diseases.

Rho-kinase inhibition ameliorates non-alcoholic fatty liver disease in type 2 diabetic rats

Non-alcoholic fatty liver disease (NAFLD) is linked to type 2 diabetes mellitus (T2DM), obesity, and insulin resistance. The Rho/ROCK pathway had been involved in the pathophysiology of diabetic complications. This study was designed to assess the possible protective impacts of the Rho/Rho-associated coiled-coil containing protein kinase (Rho/ROCK) inhibitor fasudil against NAFLD in T2DM rats trying to elucidate the underlying mechanisms. Animals were assigned into control rats, non-treated diabetic rats with NAFLD, and diabetic rats with NAFLD that received fasudil treatment (10 mg/kg per day) for 6 weeks. The anthropometric measures and biochemical analyses were performed to assess metabolic and liver function changes. The inflammatory and oxidative stress markers and the histopathology of rat liver tissues were also investigated. Groups with T2DM showed increased body weight, serum glucose, and insulin resistance. They exhibited disturbed lipid profile, enhancement of inflammatory cytokines, and deterioration of liver function. Fasudil administration reduced body weight, insulin resistance, and raised liver enzymes. It improved the disturbed lipid profile and attenuated liver inflammation. Moreover, it slowed down the progression of high fat diet (HFD)-induced liver injury and reduced the caspase-3 expression. The present study demonstrated beneficial amelioration effect of fasudil on NAFLD in T2DM. The mechanisms underlying these impacts are improving dyslipidemia, attenuating oxidative stress, downregulated inflammation, improving mitochondrial architecture, and inhibiting apoptosis.

Sevoflurane and isoflurane inhibit KCl-induced, Rho kinase-mediated, and PI3K-participated vasoconstriction in aged diabetic rat aortas

BACKGROUND

The mechanism of volatile anesthetics on vascular smooth muscle (VSM) contraction in the setting of diabetes mellitus (DM) remains unclear. The current study was designed to determine the effects of sevoflurane (SEVO) and isoflurane (ISO) on phosphoinositide 3-kinase (PI3K) and Rho kinase (ROCK) mediated KCl-induced vasoconstriction in aged type 2 diabetic rats.

METHODS

KCl-induced (60 mM) contractions were examined in endothelium-denuded aortic rings from aged T2DM Otsuka Long-Evans Tokushima Fatty (OLETF) rats (65-70 weeks old), control age-matched nondiabetic Long-Evans Tokushima Otsuka (LETO) rats and young Wistar rats (6-8 weeks old). The effects of SEVO or ISO (1-3 minimum alveolar concentration, MAC) on KCl-induced vasoconstriction, as well as those of LY294002 (PI3K inhibitor) and Y27632 (ROCK inhibitor) were measured in aortic rings from the three groups using an isometric force transducer.

RESULTS

KCl induced rapid and continuous contraction of aortic smooth muscle in the three groups, and the contraction was more obvious in OLETF rats. SEVO and ISO inhibited KCl-induced vasoconstriction in a concentration-dependent manner and were suppressed by LY294002 (10 µM) and Y27632 (1 µM). SEVO had a stronger inhibitory effect on the aortas of young Wistar rats than ISO, especially at 2 MAC and 3 MAC (P < 0.05). In aged rats, the inhibitory effect of ISO was stronger than that of SEVO, especially OLETF rats. There was no significant difference in the effects of different concentrations of ISO on arterial contraction among the three groups (P > 0.05). The effects of 1 MAC SEVO on Wistar rats and 3 MAC SEVO on OLETF rats, however, were noticeably and significantly different (P < 0.05). Compared with the control condition, LY294002 and Y27632 had the most noticeable effect on the KCl-induced contraction of aortic rings in OLETF rats (P < 0.01).

CONCLUSION

SEVO (3 MAC), ISO (1, 2, 3 MAC), LY294002 and Y27632 have more significant inhibitory effect on the contraction of vascular smooth muscle in aged T2MD rats. The mechanism of SEVO and ISO in vascular tension in T2DM is partly due to changes in PI3K and/or Rho kinase activity.

Targeting Small GTPases and Their Prenylation in Diabetes Mellitus

A fundamental role of pancreatic β-cells to maintain proper blood glucose level is controlled by the Ras superfamily of small GTPases that undergo post-translational modifications, including prenylation. This covalent attachment with either a farnesyl or a geranylgeranyl group controls their localization, activity, and protein–protein interactions. Small GTPases are critical in maintaining glucose homeostasis acting in the pancreas and metabolically active tissues such as skeletal muscles, liver, or adipocytes. Hyperglycemia-induced upregulation of small GTPases suggests that inhibition of these pathways deserves to be considered as a potential therapeutic approach in treating T2D. This Perspective presents how inhibition of various points in the mevalonate pathway might affect protein prenylation and functioning of diabetes-affected tissues and contribute to chronic inflammation involved in diabetes mellitus (T2D) development. We also demonstrate the currently available molecular tools to decipher the mechanisms linking the mevalonate pathway’s enzymes and GTPases with diabetes.

Isoliquiritigenin attenuates inflammation and modulates Nrf2/caspase-3 signalling in STZ-induced aortic injury

OBJECTIVES

The current study provides evidence on the ameliorative impact of Isoliquiritigenin (ISL), a natural bioflavonoid isolated from licorice roots against diabetes mellitus (DM)-induced aortic injury in rats.

METHODS

DM was induced in male Sprague-Dawley rats by single I.P. injection of STZ (50 mg/kg). ISL was administrated daily (20 mg/kg, orally) for 8 wks.

KEY FINDINGS

Diabetic group showed a significant aortic injury with evidence of atherosclerotic lesions development. Daily ISL (20 mg/kg, orally) administration for 8 wks significantly restored aortic oxidative/antioxidative stress homeostasis via modulating NrF-2/Keap-1/HO-1. Moreover, ISL treatment restored aortic levels of IL-10 and dampened aortic levels of IL-6 and TNF-α. Caspase-3 expression significantly declined as well. Further, ISL treatment successfully suppressed aortic endothelin-1 (ET-1) expression and restored NO contents, eNOS immunostaining paralleled with retraction in atherosclerotic lesions development, and lipid deposition with histopathological architectural preservation and restoration of almost normal aortic thickness.

CONCLUSION

ISL can be proposed to be an effective protective therapy to prevent progression of DM-induced vascular injury and to preserve aortic integrity.

Berberine elevates mitochondrial membrane potential and decreases reactive oxygen species by inhibiting the Rho/ROCK pathway in rats with diabetic encephalopathy

OBJECTIVES

Diabetic encephalopathy (DE) is a serious complication of diabetes mainly occurring in the elderly patients. Berberine (BBR) is an isoquinoline alkaloids extracted from Coptis chinensis that is applied in the treatment of diabetes clinically. This study explored the possible mechanism of BBR in relieving DE.

METHODS

Wistar rats were injected with streptozotocin and fed a high fat diet to establish the model of DE. The model rats were treated with BBR. The body weight, blood glucose and insulin of rats were measured, and Morris water maze test was conducted to evaluate the learning and memory abilities. The pathological conditions of cortical tissues were detected. The cortical mitochondria membrane potential (MMP) and reactive oxygen species (ROS) were monitored. The expressions of Rho/ROCK pathway-related genes of rat cortex were detected. The changes of MMP and ROS were detected after the treatment of Rho/ROCK pathway activator.

RESULTS

The body weight of model rats changed little, and levels of blood glucose and insulin were increased. The spatial learning and memory abilities were impaired, with disordered cortical neurons, and obvious neurons apoptosis and glia proliferation. BBR alleviated cognitive dysfunction and pathological damage in rats with DE. BBR enhanced cortical MMP and suppressed ROS. BBR treatment inhibited the Rho/ROCK pathway. Activation of the Rho/ROCK pathway reversed the effects of BBR on MMP and ROS.

CONCLUSION

BBR elevated MMP and reduced ROS in rats with DE by inhibiting the Rho/ROCK pathway. This study may offer novel insights for the management of DE.

Abnormal Ca2+ handling contributes to the impairment of aortic smooth muscle contractility in Zucker diabetic fatty rats

Vascular dysfunction is a common pathological basis for complications in individuals affected by diabetes. Previous studies have established that endothelial dysfunction is the primary contributor to vascular complications in type 2 diabetes (T2DM). However, the role of vascular smooth muscle cells (VSMCs) in vascular complications associated with T2DM is still not completely understood. The aim of this study is to explore the potential mechanisms associated with Ca²⁺ handling dysfunction and how this dysfunction contributes to diabetic vascular smooth muscle impairment. The results indicated that endothelium-dependent vasodilation was impaired in diabetic aortae, but endothelium-independent vasodilation was not altered. Various vasoconstrictors such as phenylephrine, U46619 and 5-HT could induce vasoconstriction in a concentration-dependent manner, such that the dose-response curve was parallel shifted to the right in diabetic aortae, compared to the control. Vasoconstrictions mediated by L-type calcium (Cav1.2) channels were attenuated in diabetic aortae, but effects mediated by store-operated calcium (SOC) channels were enhanced. Intracellular Ca²⁺ concentration ([Ca²⁺]_i) in VSMCs was detected by Fluo-4 calcium fluorescent probes, and demonstrated that SOC-mediated Ca²⁺ entry was increased in diabetic VSMCs. VSMC-specific knockout of STIM1 genes decreased SOC-mediated and phenylephrine-induced vasoconstrictive response in mice aortae. Additionally, Orai1 expression was up-regulated, Cav1.2 expression was downregulated, and the phenotypic transformation of diabetic VSMCs was determined in diabetic aortae. The overexpression of Orai1 markedly promoted the OPN expression of VSMCs, whereas SKF96365 (SOC channel blocker) reversed the phenotypic transformation of diabetic VSMCs. Our results demonstrated that the vasoconstriction response of aortic smooth muscle was weakened in type 2 diabetic rats, which was related to the downregulation of the Cav1.2 channel and the up-regulation of the SOC channel signaling pathway.

Fasudil ameliorates the ischemia/reperfusion oxidative injury in rat hearts through suppression of myosin regulatory light chain/NADPH oxidase 2 pathway

Fasudil is a potent Rho-kinase (ROCK) inhibitor and can relax smooth muscle or cardiac muscle contraction through decreasing the phosphorylation level of myosin regulatory light chain (p-MLC₂₀ or p-MLC2v), while p-MLC2v can function as a transcription factor to promote the NADPH oxidase 2 (NOX2) expression in rat hearts subjected to ischemia/reperfusion (I/R). This study aims to explore whether fasudil can protect the rat hearts against I/R oxidative injury through suppressing NOX2 expression via reduction of p-MLC2v level. The SD rat hearts were subjected to 1h-ischemia plus 3h-reperfusion, which showed myocardial injuries (myocardial fiber loss and disarray, increase of creatine kinase release and myocardial infarction/apoptosis), increase in ROCK activity and nuclear p-MLC_2v level concomitant with up-regulation of NOX2 and H₂O₂ production; these phenomena were attenuated by fasudil in a dose-dependent manner. Next, we verified the cardioprotective effect of fasudil and the underlying mechanisms in hypoxia-reoxygenation (H/R) -treated H9c2 cells. Consistent with the results in vivo, the H/R-treated H9c2 cells showed cellular injury (increase in apoptotic ratio), elevation in ROCK activity and nuclear p-MLC_2v level, accompanied by up-regulation of NOX2 and H₂O₂ production; these effects were blocked in the presence of fasudil in a dose-dependent way. Based on these observations, we conclude that beneficial effect of fasudil against myocardial I/R or H/R oxidative injury is related to the suppression of NOX2 expression through decrease of the p-MLC2v level. Our findings also highlight that intervention of MLC2v phosphorylation by drugs may provide a novel strategy to protect heart from I/R oxidative injury.