Rho/ROCK pathway and neural regeneration: a potential therapeutic target for central nervous system and optic nerve damage

Rho-associated kinase (ROCK) is a serine/threonine kinase and one of the major downstream effectors of the small GTPase RhoA. The Rho/ROCK pathway is closely related to the pathogenesis of several central nervous system (CNS) disorders, and involved in many aspects of neuronal functions including neurite outgrowth and retraction. In the adult CNS, the damaged neuron regeneration is very difficult due to the presence of myelin-associated axon growth inhibitors such as Nogo, myelin-associated glycoprotein (MAG) and oligodendrocyte-myelin glycoprotein (Omgp), etc. The effects of these axon growth inhibitors are reversed by blocking the Rho/ROCK pathway 47 vitro, and the inhibition of Rho/ROCK pathway can promote axon regeneration and functional recovery in the injured CNS in viva In addition, the therapeutic effects of the Rho/ROCK inhibitors have also been demonstrated in some animal models and the Rho/ROCK pathway becomes an attractive target for the development of drugs for treating CNS disorders. In this review, we summarized on the effect of the Rho and the downstream factor ROCK in neural regeneration, and the potential therapeutic effect of Rho/ROCK inhibitors in the survival and axonal regeneration of retinal ganglion cell was also discussed.

Mitochondrial oxidative damage and apoptosis induced by high glucose through Rho kinase signal pathway in renal tubular epithelial cells

Objective:To investigate the role of oxidative stress in human renal tubular epithelial cells(HK-2)induced by high glucose and the underlying signal pathway in vitro.Methods:MYPT1,pro-caspase-3,PGC-1α,and Drpl protein expressions were measured by Western blot.MnSOD2,Drp1 and PGC-1αmRNA expressions were detected by real time PCR.Results:Results showed that high glucose significantly up-regulated the protein expressions of MYPT1,pro-caspase-3 and the mRNA expression of MnSOD2 in HK-2 cells;while Rho kinase inhibitor fasudil and ROCK1 siRNA inhibited protein expressions of pro-caspase-3 and the mRNA expression of MnSOD2 in HK-2 cells induced by high glucose.Importantly,fasudil and ROCK1 siRNA markedly inhibited the expressions of mitochondrial motor proteins Drp1 and mitochondrial gene PGC-la in HK-2 cell=s induced by high glucose.Conclusions:Our findings suggest that Rho kinase signal pathway is involved in mitochondrial oxidative damage and apoptosis in high glucose-induced renal tubular epithelial cells by regulating mitochondrial motor proteins Drp1 and mitochondrial gene PGC-1α.Targeting Rho kinase signal pathway might be a potential strategy for the treatment of diabetic nephropathy.

Rho/Rock signal transduction pathway is required for MSC tenogenic differentiation

Mesenchymal stem cell （MSC）-based treatments have shown promise for improving tendon healing and repair. MSCs have the potential to differentiate into multiple lineages in response to select chemical and physical stimuli, including into tenocytes. Cell elongation and cytoskeletal tension have been shown to be instrumental to the process of MSC differentiation. Previous studies have shown that inhibition of stress fiber formation leads MSCs to default toward an adipogenic lineage, which suggests that stress fibers are required for MSCs to sense the environmental factors that can induce differentiation into tenocytes. As the Rho/ROCK signal transduction pathway plays a critical role in both stress fiber formation and in cell sensation, we examined whether the activation of this pathway was required when inducing MSC tendon differentiation using rope-like silk scaffolds. To accomplish this, we employed a loss-of-function approach by knocking out ROCK, actin and myosin （two other components of the pathway） using the specific inhibitors Y-27632, Latrunculin A and blebbistatin, respectively. We demonstrated that independently disrupting the cytoskeleton and the Rho/ ROCK pathway abolished the expression of tendon differentiation markers and led to a loss of spindle morphology. Together, these studies suggest that the tension that is generated by MSC elongation is essential for MSC teno-differentiation and that the Rho/ROCK pathway is a critical mediator of tendon differentiation on rope-like silk scaffolds.

“Baihui”(DU20)-penetrating“Qubin”(GB7)acupuncture on blood–brain barrier integrity in rat intracerebral hemorrhage models via the RhoA/ROCKⅡ/MLC 2 signaling pathway

Background:Blocking the Rho A/ROCKⅡ/MLC 2(Ras homolog gene family member A/Rho kinaseⅡ/myosin light chain 2)signaling pathway can initiate neuroprotective mechanisms against neurological diseases such as stroke,cerebral ischemia,and subarachnoid hemorrhage.Nevertheless,it is not clear whether and how disrupting the Rho A/ROCKⅡ/MLC 2 signaling pathway changes the pathogenic processes of the blood–brain barrier(BBB)after intracerebral hemorrhage(ICH).The present investigation included the injection of rat caudal vein blood into the basal ganglia area to replicate the pathophysiological conditions caused by ICH.Methods:Scalp acupuncture(SA)therapy was performed on rats with ICH at the acupuncture point“Baihui”-penetrating“Qubin,”and the ROCK selective inhibitor fasudil was used as a positive control to evaluate the inhibitory effect of acupuncture on the Rho A/ROCKⅡ/MLC 2 signaling pathway.Post-assessments included neurological deficits,brain edema,Evans blue extravasation,Western blot,quantitative polymerase chain reaction,and transmission electron microscope imaging.Results:We found that ROCKⅡacts as a promoter of the Rho A/ROCKⅡ/MLC 2 signaling pathway,and its expression increased at 6 h after ICH,peaked at 3 days,and then decreased at 7 days after ICH,but was still higher than the preintervention level.According to some experimental results,although 3 days is the peak,7 days is the best time point for acupuncture treatment.Starting from 6 h after ICH,the neurovascular structure and endothelial cell morphology around the hematoma began to change.Based on the changes in the promoter ROCKⅡ,a 7-day time point was selected as the breakthrough point for treating ICH model rats in the main experiment.The results of this experiment showed that both SA at“Baihui”-penetrating“Qubin”and treatment with fasudil could improve the expression of endothelial-related proteins by inhibiting the Rho A/ROCKⅡ/MLC 2 signaling pathway and reduce neurological dysfunction,brain edema,and BBB permeability in rats.Conclusion:This study found that these experimental data indicated that SA at“Baihui”-penetrating“Qubin”could preserve BBB integrity and neurological function recovery after ICH by inhibiting Rho A/ROCKⅡ/MLC 2 signaling pathway activation and by regulating endothelial cell–related proteins.

Effect of electroacupuncture on the mRNA and protein expression of Rho-A and Rho-associated kinase Ⅱ in spinal cord injury rats

Electroacupuncture is beneficial for the recovery of spinal cord injury, but the underlying mechanism is unclear. The Rho/Rho-associated kinase（ROCK） signaling pathway regulates the actin cytoskeleton by controlling the adhesive and migratory behaviors of cells that could inhibit neurite regrowth after neural injury and consequently hinder the recovery from spinal cord injury. Therefore, we hypothesized electroacupuncture could affect the Rho/ROCK signaling pathway to promote the recovery of spinal cord injury. In our experiments, the spinal cord injury in adult Sprague-Dawley rats was caused by an impact device. Those rats were subjected to electroacupuncture at Yaoyangguan（GV3）, Dazhui（GV14）, Zusanli（ST36） and Ciliao（BL32） and/or monosialoganglioside treatment. Behavioral scores revealed that the hindlimb motor functions improved with those treatments. Real-time quantitative polymerase chain reaction, fluorescence in situ hybridization and western blot assay showed that electroacupuncture suppressed the m RNA and protein expression of Rho-A and Rho-associated kinase Ⅱ（ROCKⅡ） of injured spinal cord. Although monosialoganglioside promoted the recovery of hindlimb motor function, monosialoganglioside did not affect the expression of Rho-A and ROCKⅡ. However, electroacupuncture combined with monosialoganglioside did not further improve the motor function or suppress the expression of Rho-A and ROCKⅡ. Our data suggested that the electroacupuncture could specifically inhibit the activation of the Rho/ROCK signaling pathway thus partially contributing to the repair of injured spinal cord. Monosialoganglioside could promote the motor function but did not suppress expression of Rho A and ROCKⅡ. There was no synergistic effect of electroacupuncture combined with monosialoganglioside.

Effect of QingguanganⅡon Rho/ROCK associated factors in the retina of DBA/2J mice

Objective:The effect of QingguanganⅡon the transcription of RhoA mRNA,ROCK mRNA,Caspase-3 mRNA and Bcl-2 mRNA in the retina of DBA/2J mice was observed.Methods:Forty-eight DBA/2J mice were randomly divided into six groups:model groups,Qingguangan II decoction group,low concentration,medium concentration and high concentration group of Qingguangan II effective ingredient and positive control group(Yimaikang tablet group),and eight C57BL/6 mice were used as blank group,DBA/2J mice were fed until 38 weeks before forming a glaucoma model,The transcription of RhoA mRNA,ROCK mRNA,Caspase-3 mRNA and Bcl-2 mRNA in the retinal of DBA/2J mice was detected using real-time fluorescence quantitative PCR(Quantitative Real-time PCR)after 4 weeks of intervention.Results:Four weeks after the intervention,In the transcription of the RhoA mRNA,ROCK mRNA and the Caspase-3 mRNA,Compared to the blank groups,Relative expression was increased in the other 6 groups,There are statistical differences in the model group,Yimaikang tablet group and low concentration group(P<0.05);In comparison to the model groups,The other 6 groups were lower than the model group,Among them,there are statistical differences between the effective groups of Qingguangan II decoction and high concentration group of Qingguangan II effective ingredient in RhoA mRNA transcription(P<0.05);In the transcription of the ROCK mRNA and the Caspase-3 mRNA,Statistics have differences between the model group and the effective component of the medium and high concentration group(P<0.05);In the Bcl-2 mRNA transcription,Compare them to blank groups,Relexpression expression decreased in the other 6 groups,Statistics have differences between model group,Qingguangan II decoction group and low concentration groups(P<0.05);The relative expression of Bcl-2 mRNA in high concentration group of effective component is higher than that of the model group,There are differences in statistics(P<0.05).Conclusion:The high concentration of QingguanganⅡprescription probably attenuated Caspase-3 transcription in retinal ganglion cells by inhibiting the Rho/ROCK signaling pathway and activated Bcl-2 expression by inhibiting ROCK signaling,which attenuated apoptosis in retinal ganglion cells.

Tanshinone ⅡA Protects against Lipopolysaccharides-lnduced Endothelial Cell Injury via Rho/Rho Kinase Pathway

Objective： To test whether tanshinone ⅡA （Tan ⅡA）, a highly valued herb derivative to treat vascular diseases in Chinese medicine, could protect endothelial cells from bacterial endotoxin （lipopolysaccharides, LPS）-induced endothelial injury. Methods： Endothelial cell injury was induced by treating human umbilical vein endothelial cells （HUVECs） with 0.2 μg/mL LPS for 24 h. Y27632 and valsartan were used as positive controls. The effects of tanshinone Ⅱ A on the LPS-induced cell viability and apoptosis rate of HUVECs were tested by flow cytometry, cell migration by transwell, adhesion by a 96-well plate pre-coated with vitronectin and cytoskeleton reorganization by immunofluorescence assay. Rho/Rho kinase （ROCK） pathway- associated gene and protein expression were examined by microarray assay; quantitative real-time polymerase chain reaction and Western blotting were used to confirm the changes observed by microarray. Results： Tan ][ A improved cell viability, suppressed apoptosis and protected cells from LPS-induced reductions in cell migration and adhesion at a comparable magnitude to that of Y27632 and valsartan. Tan II A, Y27632 and valsartan also normalized LPS-induced actomyosin contraction and vinculin protein aggregation. A microarray assay revealed increased levels of fibronectin, integrin A5 （ITG A5）, Ras homolog gene family member A （RheA）, myosin light chain phosphatase, phosphatidylinositol-4,5-bisphosphate 3-kinase （PI3K, or PIP2 in Western blotting）, focal adhesion kinase, vascular endothelial growth factor and vascular endothelial growth factor receptor 2 in the damaged HUVECs, which were attenuated to different degrees by Tan ⅡA, Y27632 and valsartan. Conclusion： Tan ⅡA exerted a strong protective effect on HUVECs, and the mechanism was caused, at least in part, by a blockade in the Rho/ROCK pathway, presumably through the down-regulation of ITG A5.

Houshiheisan and its components promote axon regeneration after ischemic brain injury

Houshiheisan,a classic prescription in traditional Chinese medicine,contains Flos Chrysanthemi,Radix Saposhnikoviae,Ramulus Cinnamomi,Rhizoma Chuanxiong,Radix et Rhizoma Asari,Radix Platycodonis,Rhizoma Atractylodis macrocephalae,Poria,Rhizoma Zingiberis,Radix Angelicae sinensis,Radix et Rhizoma Ginseng,Radix Scutellariae and Concha Ostreae.According to traditional Chinese medicine theory,Flos Chrysanthemi,Radix Saposhnikoviae,Ramulus Cinnamomi,Rhizoma Chuanxiong,Radix et Rhizoma Asari and Radix Platycodonis are wind-dispelling drugs;Rhizoma Atractylodis macrocephalae,Poria,Rhizoma Zingiberis,Radix Angelicae sinensis and Radix et Rhizoma Ginseng are deficiency-nourishing drugs.A large number of randomized controlled trials have shown that Houshiheisan is effective in treating stroke,but its mechanism of action is unknown.Axonal remodeling is an important mechanism in neural protection and regeneration.Therefore,this study explored the effect and mechanism of action of Houshiheisan on the repair of axons after cerebral ischemia.Rat models of focal cerebral ischemia were established by ligating the right middle cerebral artery.At 6 hours after model establishment,rats were intragastrically administered 10.5 g/kg Houshiheisan or 7.7 g/kg wind-dispelling drug or 2.59 g/kg deficiency-nourishing drug.These medicines were intragastrically administered as above every 24 hours for 7 consecutive days.Houshiheisan,and its wind-dispelling and deficiency-nourishing components reduced the neurological deficit score and ameliorated axon and neuron lesions after cerebral ischemia.Furthermore,Houshiheisan,and its wind-dispelling and deficiency-nourishing components decreased the expression of proteins that inhibit axonal remodeling：amyloid precursor protein,neurite outgrowth inhibitor protein A（Nogo-A）,Rho family small GTPase A（Rho A） and Rho-associated kinase 2（Rock2）,and increased the expression of growth associated protein-43,microtubule-associated protein-2,netrin-1,Ras-related C3 botulinum toxin substrate 1（Rac1） and cell division cycle 42（Cdc42）.The effect of Houshiheisan was stronger than wind-dispelling drugs or deficiency-nourishing drugs alone.In conclusion,Houshiheisan,and wind-dispelling and deficiency-nourishing drugs promote the repair of axons and nerve regeneration after cerebral ischemia through Nogo-A/Rho A/Rock2 and Netrin-1/Rac1/Cdc42 signaling pathways.These effects are strongest with Houshiheisan.

Environmental enrichment combined with fasudil promotes motor function recovery and axonal regeneration after stroke

Fasudil,a Rho-associated protein kinase(ROCK)inhibitor,has a protective effect on the central nervous system.In addition,environmental enrichment is a promising technique for inducing the recovery of motor impairments in ischemic stroke models.The present study aimed to explore whether environmental enrichment combined with fasudil can facilitate motor function recovery and induce cortical axonal regeneration after stroke.First,a mouse model of ischemic cerebral stroke was established by photochemical embolization of the left sensorimotor cortex.Fasudil solution(10 mg/kg per day)was injected intraperitoneally for 21 days after the photothrombotic stroke.An environmental enrichment intervention was performed on days 7-21 after the photothrombotic stroke.The results revealed that environmental enrichment combined with fasudil improved motor function,increased growth-associated protein 43 expression in the infarcted cerebral cortex,promoted axonal regeneration on the contralateral side,and downregulated ROCK,p-LIM domain kinase(LIMK)1,and p-cofilin expression.The combined intervention was superior to monotherapy.These findings suggest that environmental enrichment combined with fasudil treatment promotes motor recovery after stroke,at least partly by stimulating axonal regeneration.The underlying mechanism might involve ROCK/LIMK1/cofilin pathway regulation.This study was approved by the Institutional Animal Care and Use Committee of Fudan University,China(approval No.20160858A232)on February 24,2016.

The potential therapeutic effect DL0805-2 on experimental pulmonary hypertensive rats and the underlying mechanisms

Aim DL0805-2 is a novel Rho-kinases inhibitor which has been found to have potent cardiovascular effects. In the present research, we aimed to study the potential of DL0805-2 in the treatment of pulmonary arterial hypertension （PAH） and discuss the underlying mechanisms preliminarily. Methods A classical PAH animal model was used, which was established by single injection of 50 mg · kg^-1 monocrotaline （MCT）. One week later, the rats were administrated with 1, 3, 10 mg · kg^-1 DL0805-2 via intraperitoneal injection for 18 days. At the end of the experiment, the body weight and survival rate were recorded. Meanwhile, the respiration function, heart function, blood pressure and pulmonary artery pressure were detected. Serum was collected for biochemical index analysis. The weight of vital organs was used to calculate the organ index. Histopathology examination was em-ployed to observe the subtle changes in hearts, vessels and lungs. Furthermore, the mechanisms were studied main- ly by the method of western blotting. Results DL0805-2 did not show significant influence on body weight of PAH rats. But the survival rate of PAH rats treated with 3 and 10 mg · kg^-1 DL0805-2 was increased up to 90. 9% com- pared with the model group （68.2%）. DL0805-2 improved the pulmonary artery blood flow especially the maximal -1 -1 velocity （PV max） from 397.2 cm · s^-1 to 506.5, 540. 1 and 574.0 cm · s^-1 respectively. The results of echocar- diography and electrocardiogram show that DL0805-2 had little effect on left ventricle and systemic circulation but attenuated right ventricle injury and decreased the right ventricle pressure from 73.73 mmHg to 47.80, 42.64 and 46.45 mmHg respectively after DL0805-2 intervention. Disease markers of PAH including NT-proBNP in serum and ET-1 in lung tissue homogenate and serum biochemical indicators, ALT, AST and LDH, were reduced by DL0805-2. DL0805-2 also relieved edema of lungs and decreased inflammatory cytokines production. Through the examination on histopathologic slide of pulmonary main artery, right ventricle and lung, DL0805 derivatives were found to have significant protection effect on structural changes of organs induced by pulmonary hypertension. Ac- cording to the preliminary study on the mechanisms of DL0805-2 in PAH, Rho/ROCK pathway was significantly in- hibited by DL0805 derivatives. In addition, DL0805 derivatives showed effect on BMPRII/p-Smad pathway and ap- optosis related pathway. Conclusion DL0805-2 has showed potent treatment effect on the PAH rats. And the un- derlying mechanisms studies also indicated that RhoA/ROCK and BMPRII pathways were involved. This work will provide basis experimental data for the further research and development of DL0805-2.