The Function of Rho-Associated Kinases ROCK1 and ROCK2 in the Pathogenesis of Cardiovascular Disease

Regulation of protein-coding gene and long noncoding RNA pairs in liver of conventional and germ-free mice following oral PBDE exposure

Gut microbiome communicates with the host liver to modify hepatic xenobiotic biotransformation and nutrient homeostasis. Polybrominated diphenyl ethers (PBDEs) are persistent environmental contaminants that are detected in fatty food, household dust, and human breast milk at worrisome levels. Recently, long noncoding RNAs (lncRNAs) have been recognized as novel biomarkers for toxicological responses and may regulate the transcriptional/translational output of protein-coding genes (PCGs). However, very little is known regarding to what extent the interactions between PBDEs and gut microbiome modulate hepatic lncRNAs and PCGs, and what critical signaling pathways are impacted at the transcriptomic scale. In this study, we performed RNA-Seq in livers of nine-week-old male conventional (CV) and germ-free (GF) mice orally exposed to the most prevalent PBDE congeners BDE-47 and BDE-99 (100 μmol/kg once daily for 4-days; vehicle: corn oil, 10 ml/kg), and unveiled key molecular pathways and PCG-lncRNA pairs targeted by PBDE-gut microbiome interactions. Lack of gut microbiome profoundly altered the PBDE-mediated transcriptomic response in liver, with the most prominent effect observed in BDE-99-exposed GF mice. The top pathways up-regulated by PBDEs were related to xenobiotic metabolism, whereas the top pathways down-regulated by PBDEs were in lipid metabolism and protein synthesis in both enterotypes. Genomic annotation of the differentially regulated lncRNAs revealed that majority of these lncRNAs overlapped with introns and 3'-UTRs of PCGs. Lack of gut microbiome profoundly increased the percentage of PBDE-regulated lncRNAs mapped to the 3'-UTRs of PCGs, suggesting the potential involvement of lncRNAs in increasing the translational efficiency of PCGs by preventing miRNA-3'-UTR binding, as a compensatory mechanism following toxic exposure to PBDEs. Pathway analysis of PCGs paired with lncRNAs revealed that in CV mice, BDE-47 regulated nucleic acid and retinol metabolism, as well as circadian rhythm; whereas BDE-99 regulated fatty acid metabolism. In GF mice, BDE-47 differentially regulated 19 lncRNA-PCG pairs that were associated with glutathione conjugation and transcriptional regulation. In contrast, BDE-99 up-regulated the xenobiotic-metabolizing Cyp3a genes, but down-regulated the fatty acid-metabolizing Cyp4 genes. Taken together, the present study reveals common and unique lncRNAs and PCG targets of PBDEs in mouse liver, and is among the first to show that lack of gut microbiome sensitizes the liver to toxic exposure of BDE-99 but not BDE-47. Therefore, lncRNAs may serve as specific biomarkers that differentiate various PBDE congeners as well as environmental chemical-mediated dysbiosis. Coordinate regulation of PCG-lncRNA pairs may serve as a more efficient molecular mechanism to combat against xenobiotic insult, and especially during dysbiosis-induced increase in the internal dose of toxicants.

Antenatal/early postnatal hypothyroidism increases the contribution of Rho-kinase to contractile responses of mesenteric and skeletal muscle arteries in adult rats

BACKGROUND

Maternal thyroid deficiency can increase Rho-kinase procontractile influence in arteries of 2-week-old progeny. Here we hypothesized that augmented role of Rho-kinase persists in arteries from adult progeny of hypothyroid rats.

METHODS

Dams were treated with 6-propyl-2-thiouracil (PTU) in drinking water (0.0007%) during pregnancy and 2 weeks postpartum; control (CON) females received PTU-free water. At the age of 10-12-weeks, serum T₃/T₄ levels did not differ between PTU and CON male offspring. Cutaneous (saphenous), mesenteric, and skeletal muscle (sural) arteries were studied by wire myography, qPCR, and Western blotting.

RESULTS

Saphenous arteries of PTU and CON groups showed similar responses to α₁-adrenoceptor agonist methoxamine and were equally suppressed by Rho-kinase inhibitor Y27632. Responses of mesenteric arteries also did not differ between PTU and CON, but the effects of Y27632 were more prominent in the PTU group. Sural arteries of PTU rats compared to CON demonstrated augmented responses to methoxamine, increased RhoA mRNA contents and higher levels of MYPT1 phosphorylation at Thr⁸⁵⁵. Intergroup differences in contractile responses and phospho-MYPT1-Thr⁸⁵⁵ were eliminated by Y27632.

CONCLUSION

Rho-kinase contribution to contractile responses of mesenteric and especially sural arteries is augmented in adult PTU rats. Therefore, maternal thyroid deficiency may have long-term detrimental consequences for vasculature in adult offspring.

Mechanisms and impact of altered tumour mechanics

The physical characteristics of tumours are intricately linked to the tumour phenotype and difficulties during treatment. Many factors contribute to the increased stiffness of tumours; from increased matrix deposition, matrix remodelling by forces from cancer cells and stromal fibroblasts, matrix crosslinking, increased cellularity, and the build-up of both solid and interstitial pressure. Increased stiffness then feeds back to increase tumour invasiveness and reduce therapy efficacy. Increased understanding of this interplay is offering new therapeutic avenues.

The level of ROCK1 and ROCK2 in patients with pulmonary hypertension in plateau area

Pulmonary hypertension (PH) is defined as the mean pulmonary artery pressure (mPAP) ≥25 mmHg under the sea level in resting state. ROCK1 and ROCK2 can be combined to cause the damage of vascular endothelial function. To explore the differences of ROCK1 and ROCK2 in subjects with pulmonary hypertension or normal pulmonary artery pressure in plateau area, and to further understand the mechanism of Rho/rho-kinase pathway activation for promoting pulmonary hypertension, we collected 64 patients with pulmonary hypertension and 87 normal pulmonary artery healthy controls. All subjects were hospitalized in Cardiology or Respiration Department of Qinghai Provincial Peoples’ Hospital from December 2016 to June 2017. The pulmonary artery systolic pressure was measured by Doppler ultrasound, and serum ROCK1 and ROCK2 levels were tested by enzyme linked immunosorbent assay (ELISA). We found that the serum ROCK2 concentration in the pulmonary hypertension group was significantly higher than that in the control group, but serum ROCK1 level had no significant difference. ROCK2 plays a leading role in pulmonary hypertension in the plateau region, so selective ROCK2 inhibitors will be more effective in improving pulmonary hypertension.

Rho signaling research: history, current status and future directions

One of the main research areas in biology from the mid‐1980s through the 1990s was the elucidation of signaling pathways governing cell responses. These studies brought, among other molecules, the small GTPase Rho to the epicenter. Rho signaling research has since expanded to all areas of biology and medicine. Here, we describe how Rho emerged as a key molecule governing cell morphogenesis and movement, how it was linked to actin reorganization, and how the study of Rho signaling has expanded from cultured cells to whole biological systems. We then give an overview of the current research status of Rho signaling in development, brain, cardiovascular system, immunity and cancer, and discuss the future directions of Rho signaling research, with emphasis on one Rho effector, ROCK*.

Fasudil improves endothelial dysfunction in rats exposed to chronic intermittent hypoxia through RhoA/ROCK/NFATc3 pathway

Endothelial dysfunction is one of the main pathological changes in Obstructive sleep apnoea (OSA). The Rho kinase (ROCK) pathway is associated with endothelial dysfunction. However, the interaction between ROCK and nuclear factor of activated T cells isoform c3 (NFATc3) in the development of this pathological response under chronic intermittent hypoxia (CIH) is unclear. To simulate the OSA model, we established a moderate CIH rat model by administering the fraction of inspired O2 (FiO2) from 21% to 9%, 20 times/h, 8 h/day for 3 weeks. Fasudil (ROCK inhibitor, 8 mg/kg/d, i.p.) was administrated in the rats exposed to CIH for 3 weeks. Our results demonstrated that CIH caused significantly endothelial dysfunction, accompanying with increased ET-1 level, decreased eNOS expression and NO production, which reduced ACh-induced vascular relaxation responses. Moreover, RhoA/ROCK-2/NFATc3 expressions were up-regulated. Fasudil significantly improved CIH induced endothelial dysfunction. Data suggested that the ROCK activation is necessary for endothelial dysfunction during CIH.

Chronophin activation is necessary in Doxorubicin-induced actin cytoskeleton alteration

Although doxorubicin (Dox)-induced oxidative stress is known to be associated with cytotoxicity, the precise mechanism remains unclear. Genotoxic stress not only generates free radicals, but also affects actin cytoskeleton stability. We showed that Dox-induced RhoA signaling stimulated actin cytoskeleton alterations, resulting in central stress fiber disruption at early time points and cell periphery cortical actin formation at a later stage, in HeLa cells. Interestingly, activation of a cofilin phosphatase, chronophin (CIN), was initially evoked by Dox-induced RhoA signaling, resulting in a rapid phosphorylated cofilin turnover leading to actin cytoskeleton remodeling. In addition, a novel interaction between CIN and 14-3-3ζ was detected in the absence of Dox treatment. We demonstrated that CIN activity is quite contrary to 14-3-3ζ binding, and the interaction leads to enhanced phosphorylated cofilin levels. Therefore, initial CIN activation regulation could be critical in Dox-induced actin cytoskeleton remodeling through RhoA/cofilin signaling. [BMB Reports 2017; 50(6): 335-340].

Mechanisms of sphingosine-1-phosphate-mediated vasoconstriction of rat afferent arterioles

AIM

Sphingosine-1-phosphate (S1P) influences resistance vessel function and is implicated in renal pathological processes. Previous studies revealed that S1P evoked potent vasoconstriction of the pre-glomerular microvasculature, but the underlying mechanisms remain incompletely defined. We postulated that S1P-mediated pre-glomerular microvascular vasoconstriction involves activation of voltage-dependent L-type calcium channels (L-VDCC) and the rho/rho kinase pathway.

METHODS

Afferent arteriolar reactivity was assessed in vitro using the blood-perfused rat juxtamedullary nephron preparation, and diameter was measured during exposure to physiological and pharmacological agents.

RESULTS

Exogenous S1P (10^-9 -10^-5 mol L^-1 ) evoked concentration-dependent vasoconstriction of afferent arterioles. Superfusion with nifedipine, a L-VDCC blocker, increased arteriolar diameter by 39 ± 18% of baseline and significantly attenuated the S1P-induced vasoconstriction. Superfusion with the rho kinase inhibitor, Y-27632, increased diameter by 60 ± 12% of baseline and also significantly blunted vasoconstriction by S1P. Combined nifedipine and Y-27632 treatment significantly inhibited S1P-induced vasoconstriction over the entire concentration range tested. In contrast, depletion of intracellular Ca²⁺ stores with the Ca²⁺ -ATPase inhibitors, thapsigargin or cyclopiazonic acid, did not alter the S1P-mediated vasoconstrictor profile. Scavenging reactive oxygen species (ROS) or inhibition of nicotinamide adenine dinucleotide phosphate oxidase activity significantly attenuated S1P-mediated vasoconstriction.

CONCLUSION

Exogenous S1P elicits potent vasoconstriction of rat afferent arterioles. These data also demonstrate that S1P-mediated pre-glomerular vasoconstriction involves activation of L-VDCC, the rho/rho kinase pathway and ROS. Mobilization of Ca²⁺ from intracellular stores is not required for S1P-mediated vasoconstriction. These studies reveal a potential role for S1P in the modulation of renal microvascular tone.

Association between biomechanical alterations and migratory ability of semaphorin-3A-treated thymocytes

BACKGROUND

Class 3 semaphorins are soluble proteins involved in cell adhesion and migration. Semaphorin-3A (Sema3A) was initially shown to be involved in neuronal guidance, and it has also been reported to be associated with immune disorders. Both Sema3A and its receptors are expressed by most immune cells, including monocytes, macrophages, and lymphocytes, and these proteins regulate cell function. Here, we studied the correlation between Sema3A-induced changes in biophysical parameters of thymocytes, and the subsequent repercussions on cell function.

METHODS

Thymocytes from mice were treated in vitro with Sema3A for 30min. Scanning electron microscopy was performed to assess cell morphology. Atomic force microscopy was performed to further evaluate cell morphology, membrane roughness, and elasticity. Flow cytometry and/or fluorescence microscopy were performed to assess the F-actin cytoskeleton and ROCK2. Cell adhesion to a bovine serum albumin substrate and transwell migration assays were used to assess cell migration.

RESULTS

Sema3A induced filopodia formation in thymocytes, increased membrane stiffness and roughness, and caused a cortical distribution of the cytoskeleton without changes in F-actin levels. Sema3A-treated thymocytes showed reduced substrate adhesion and migratory ability, without changes in cell viability. In addition, Sema3A was able to down-regulate ROCK2.

CONCLUSIONS

Sema3A promotes cytoskeletal rearrangement, leading to membrane modifications, including increased stiffness and roughness. This effect in turn affects the adhesion and migration of thymocytes, possibly due to a reduction in ROCK2 expression.

GENERAL SIGNIFICANCE

Sema3A treatment impairs thymocyte migration due to biomechanical alterations in cell membranes.

Cerebral Cavernous Malformation 1/2 complex controls ROCK1 and ROCK2 complementary functions for endothelial integrity

Endothelial integrity relies on a mechanical crosstalk between intercellular and cell-matrix interactions. This cross-talk is compromised in hemorrhagic vascular lesions of patients carrying loss-of-function mutations in CCM genes. RhoA/ROCK-dependent cytoskeletal remodeling is central to the disease as it causes unbalanced cell adhesion towards increased cell-extracellular matrix adhesions and destabilized cell-cell junctions. Our study reveals that CCM proteins directly orchestrate ROCK1 and ROCK2 complementary roles on the mechanics of the endothelium. CCM proteins act as a scaffold promoting ROCK2 interactions with VE-cadherin and limiting ROCK1 kinase activity. Loss of CCM1 produces excessive ROCK1-dependent actin stress fibers and destabilizes intercellular junctions. Silencing of ROCK1 but not ROCK2 restores the adhesive and mechanical homeostasis of CCM1/2-depleted endothelial monolayers and rescues cardiovascular defects of ccm1 mutant zebrafish embryos. Conversely, knocking down of Rock2 but not Rock1 in WT zebrafish embryos generates defects reminiscent of the ccm1 mutant phenotypes. Our study uncovers the role of the CCM complex in controlling ROCK1 and ROCK2 to preserve endothelial integrity and drive heart morphogenesis. Moreover, it identifies solely the ROCK1 isoform as therapeutic target for the CCM disease.

Cardiovascular Risk Factors and Markers

Cardiovascular risk is assessed for the prediction and appropriate management of patients using collections of identified risk markers obtained from clinical questionnaire information, concentrations of certain blood molecules (e.g., N-terminal proB-type natriuretic peptide fragment and soluble receptors of tumor-necrosis factor-α and interleukin-2), imaging data using various modalities, and electrocardiographic variables, in addition to traditional risk factors.

Mechanotransduction Mechanisms in Mitral Valve Physiology and Disease Pathogenesis

The mitral valve exists in a mechanically demanding environment, with the stress of each cardiac cycle deforming and shearing the native fibroblasts and endothelial cells. Cells and their extracellular matrix exhibit a dynamic reciprocity in the growth and formation of tissue through mechanotransduction and continuously adapt to physical cues in their environment through gene, protein, and cytokine expression. Valve disease is the most common congenital heart defect with watchful waiting and valve replacement surgery the only treatment option. Mitral valve disease (MVD) has been linked to a variety of mechano-active genes ranging from extracellular components, mechanotransductive elements, and cytoplasmic and nuclear transcription factors. Specialized cell receptors, such as adherens junctions, cadherins, integrins, primary cilia, ion channels, caveolae, and the glycocalyx, convert mechanical cues into biochemical responses via a complex of mechanoresponsive elements, shared signaling modalities, and integrated frameworks. Understanding mechanosensing and transduction in mitral valve-specific cells may allow us to discover unique signal transduction pathways between cells and their environment, leading to cell or tissue specific mechanically targeted therapeutics for MVD.

Common variants of ROCKs and the risk of hypertension, and stroke: Two case-control studies and a follow-up study in Chinese Han population

The Rho kinases (ROCKs) are recognized as a critical regulator of vascular functions in cardiovascular disorders. It is crucial to illustrate the association of ROCKs genetic variation and hypertension and/or stroke events. Herein we aimed at investigating the association of ROCK1 and ROCK2 with hypertension and stroke in Chinese Han population. Seven tagSNPs at ROCK1 and ROCK2 were genotyped in a community-based case-control study consisting of 2012 hypertension cases and 2210 normotensive controls and 4128 subjects were further followed up. In stroke case-control study, 1471 ischemic stroke (IS) inpatients and 607 hemorrhagic stroke (HS) inpatients were collected, and 2443 age-matched controls were selected from the follow-up population. Risks were estimated as odds ratio (OR) and hazard ratio (HR) by logistic and Cox regression. The community-based case-control study didn't identify any significant tagSNPs associated with hypertension even after adjustment for covariates. The follow-up analysis showed that rs1481280 of ROCK1 significantly associated with incident hypertension (HR=1.130, P=0.048) after adjusting for covariates. rs7589629 and rs978906 of ROCK2 were significantly associated with incident IS (HR=1.373, P=0.004; HR=1.284, P=0.026) respectively. In stroke case-control study, rs288980, rs1481280 and rs7237677 were significantly associated with IS and the adjusted ORs (P values) of additive model were 0.879 (0.010), 0.895 (0.036) and 0.857 (0.002) respectively. Furthermore, rs288980, rs7237677 and rs978906 were significantly associated with HS and the adjusted ORs (P values) of additive model were 0.857 (0.025), 0.848 (0.018) and 0.856 (0.027) respectively. Our findings suggest that ROCK1 and ROCK2 contribute to the genetic susceptibility of hypertension and stroke.

Rho Kinase Regulates Aortic Vascular Smooth Muscle Cell Stiffness Via Actin/SRF/Myocardin in Hypertension

Background/Aims:

Our previous studies demonstrated that intrinsic aortic smooth muscle cell (VSMC) stiffening plays a pivotal role in aortic stiffening in aging and hypertension. However, the underlying molecular mechanisms remain largely unknown. We here hypothesized that Rho kinase (ROCK) acts as a novel mediator that regulates intrinsic VSMC mechanical properties through the serum response factor (SRF)/myocardin pathway and consequently regulates aortic stiffness and blood pressure in hypertension.

Methods:

Four-month old male spontaneously hypertensive rats (SHR) and Wistar-Kyoto (WKY) rats were studied. Aortic stiffness was measured by echography. Intrinsic mechanical properties of VSMCs were measured by atomic force microscopy (AFM) in vitro.

Results:

Compared to WKY rats, SHR showed a significant increase in aortic stiffness and blood pressure, which is accompanied by a remarkable cell stiffening and ROCK activation in thoracic aortic (TA) VSMCs. Theses alterations in SHR were abolished by Y-27632, a specific inhibitor of ROCK. Additionally, boosted filamentous/globular actin ratio was detected in TA VSMCs from SHRversus WKY rats, resulting in an up-regulation of SRF and myocardin expression and its downstream stiffness-associated genes including α-smooth muscle actin, SM22, smoothelin and myosin heavy chain 11. Reciprocally, these alterations in SHR TA VSMCs were also suppressed by Y-27632. Furthermore, a specific inhibitor of SRF/myocardin, CCG-100602, showed a similar effect to Y-27632 in SHR in both TA VSMCs stiffness in vitro and aorta wall stiffness in vivo.

Conclusion:

ROCK is a novel mediator modulating aortic VSMC stiffness through SRF/myocardin signaling which offers a therapeutic target to reduce aortic stiffening in hypertension.

Nicorandil regulates the macrophage skewing and ameliorates myofibroblasts by inhibition of RhoA/Rho-kinase signalling in infarcted rats

We have demonstrated that ATP-sensitive potassium (K_ATP ) channel agonists attenuated fibrosis; however, the mechanism remained unclear. Since RhoA has been identified as a mediator of cardiac fibrosis, we sought to determine whether the anti-fibrotic effects of K_ATP channel agonists were mediated via regulating macrophage phenotype and fibroblast differentiation by a RhoA/RhoA-kinase-dependent pathway. Wistar male rats after induction of myocardial infarction were randomized to either vehicle, nicorandil, an antagonist of K_ATP channel glibenclamide, an antagonist of ROCK fasudil, or a combination of nicorandil and glibenclamide or fasudil and glibenclamide starting 24 hrs after infarction. There were similar infarct sizes among the infarcted groups. At day 3 after infarction, post-infarction was associated with increased RhoA/ROCK activation, which can be inhibited by administering nicorandil. Nicorandil significantly increased myocardial IL-10 levels and the percentage of regulatory M2 macrophages assessed by immunohistochemical staining, Western blot, and RT-PCR compared with vehicle. An IL-10 receptor antibody increased myofibroblast infiltration compared with nicorandil alone. At day 28 after infarction, nicorandil was associated with attenuated cardiac fibrosis. These effects of nicorandil were functionally translated in improved echocardiographically derived cardiac performance. Fasudil showed similarly increased expression of M2 macrophages as nicorandil. The beneficial effects of nicorandil on fibroblast differentiation were blocked by adding glibenclamide. However, glibenclamide cannot abolish the attenuated fibrosis of fasudil, implying that RhoA/RhoA-kinase is a downstream effector of K_ATP channel activation. Nicorandil polarized macrophages into M2 phenotype by inhibiting RhoA/RhoA-kinase pathway, which leads to attenuated myofibroblast-induced cardiac fibrosis after myocardial infarction.

Rho-kinase inhibition reverses impaired Ca2+ handling and associated left ventricular dysfunction in pressure overload-induced cardiac hypertrophy

Recent studies have implicated a relationship between RhoA/ROCK activity and defective Ca2+ homeostasis in hypertrophic hearts. This study investigated molecular mechanism underlying ROCK inhibition-mediated cardioprotection against pressure overload-induced cardiac hypertrophy, with a focus on Ca2+ homeostasis. Cardiac hypertrophy model was established by performing transverse aortic constriction (TAC) in 8-week-old male rats. Groups were assigned as SHAM, TAC and TAC+Fas (rats undergoing TAC and treated with fasudil). Rats in the TAC+Fas group were administered fasudil (5mg/kg/day), and rats in the SHAM and TAC groups were treated with vehicle for 10 weeks. Electrophysiological recordings were obtained from isolated left ventricular myocytes and expression levels of proteins were determined using western blotting. Rats in the TAC group showed remarkable cardiac hypertrophy, and fasudil treatment significantly reversed this alteration. TAC+Fas myocytes showed significant improvement in reduced contractility and Ca2+ transients. Moreover, these myocytes showed restoration of slow relaxation rate and Ca2+ reuptake. Although L-type Ca2+ currents did not change in TAC group, there was a significant reduction in the triggered Ca2+ transients which was reversed either by long-term fasudil treatment or incubation of TAC myocytes with fasudil. The hearts of rats in the TAC group showed a significant decrease in ROCK1, ROCK2, RyR2 protein levels and p-PLBS16/T17/SERCA2 ratio and increase in RhoA expression and MLC phosphorylation. However, fasudil treatment largely reversed TAC-induced alterations in protein expression. Thus, our findings indicate that upregulation of the RhoA/ROCK pathway is significantly associated with cardiac hypertrophy-related Ca2+ dysregulation and suggest that ROCK inhibition prevents hypertrophic heart failure.

Treatment of the cardiac hypertrophic response and heart failure with ginseng, ginsenosides, and ginseng-related products

Heart failure is a major medical and economic burden throughout the world. Although various treatment options are available to treat heart failure, death rates in both men and women remain high. Potential adjunctive therapies may lie with use of herbal medications, many of which possess potent pharmacological properties. Among the most widely studied is ginseng, a member of the genus Panax that is grown in many parts of the world and that has been used as a medical treatment for a variety of conditions for thousands of years, particularly in Asian societies. There are a number of ginseng species, each possessing distinct pharmacological effects due primarily to differences in their bioactive components including saponin ginsenosides and polysaccharides. While experimental evidence for salutary effects of ginseng on heart failure is robust, clinical evidence is less so, primarily due to a paucity of large-scale well-controlled clinical trials. However, there is evidence from small trials that ginseng-containing Chinese medications such as Shenmai can offer benefit when administered as adjunctive therapy to heart failure patients. Substantial additional studies are required, particularly in the clinical arena, to provide evidence for a favourable effect of ginseng in heart failure patients.

Rho-associated protein kinases as therapeutic targets for both vascular and parenchymal pathologies in Alzheimer's disease

The causes of late-onset Alzheimer's disease are unclear and likely multifactorial. Rho-associated protein kinases (ROCKs) are ubiquitously expressed signaling messengers that mediate a wide array of cellular processes. Interestingly, they play an important role in several vascular and brain pathologies implicated in Alzheimer's etiology, including hypertension, hypercholesterolemia, blood-brain barrier disruption, oxidative stress, deposition of vascular and parenchymal amyloid-beta peptides, tau hyperphosphorylation, and cognitive decline. The current review summarizes the functions of ROCKs with respect to the various risk factors and pathologies on both sides of the blood-brain barrier and present support for targeting ROCK signaling as a multifactorial and multi-effect approach for the prevention and amelioration of late-onset Alzheimer's disease. This article is part of the Special Issue "Vascular Dementia".

Short-Term Effects of Y-27632, a Rho-Associated Protein Kinase Inhibitor, on Chromatin Supraorganization and DNA Amount in Epithelial Cells of the Rat Cornea and Limbus

PURPOSE

To assess the short-term effects of instilling Y-27632, an inhibitor of Rho/Rho-associated protein kinases, on the chromatin supraorganization and DNA amount of corneal and limbal epithelial cells of healthy rats.

METHODS

Longitudinal sections (7 μm) of enucleated eyes of healthy rats that received, by instillation, balanced salt solution with or without 10 mM of Y-27632 daily for 7 or 15 days, were subjected to the Feulgen reaction. Feulgen-stained nuclei of corneal and limbal epithelial cells were studied by microscopy and video image analysis to establish the nuclear size (area and perimeter), supraorganization of chromatin (texture and degrees of condensation), and the Feulgen-DNA amount.

RESULTS

Instillation of Y-27632 for up to 15 days did not change the size of the nucleus or the chromatin texture of corneal and limbal epithelial cells. Samples treated with Y-27632 for 7 days showed condensed chromatin and a high Feulgen-DNA amount. Both corneal and limbal epithelium showed the presence of near-tetraploid nuclei corresponding to cells in the S and G2 phases of the cell cycle. The degrees of condensation and Feulgen-DNA amount of the nuclei of epithelial cells of the cornea and limbus of eyes from rats receiving Y-27632 for 15 days did not differ from control (no drug).

CONCLUSIONS

Changes in chromatin supraorganization and DNA amount, such as seen in this study, are indicative of cell proliferation and do not seem to be associated with disturbances in gene activity and transcription of DNA.

Effects of Total Flavone from Rhododendron simsii Planch. Flower on Postischemic Cardiac Dysfunction and Cardiac Remodeling in Rats

This study investigated the effect of total flavone from Rhododendron simsii Planch. flower (TFR) on postischemic cardiac dysfunction and ventricular remodeling and was to test the hypothesis that TFR has an antiventricular remodeling effect through inhibition of urotensin-II receptor- (UTR-) mediated activation of RhoA-ROCK pathways. Twenty-four hours after ligation of the left anterior descending coronary artery, male Sprague-Dawley rats were randomized to receive 4-week treatment with saline (model group) or TFR. Compared to the model group, TFR treatment restored cardiac function, attenuated cardiomyocyte hypertrophy, and reduced interstitial fibrosis. Expression levels of several fibrosis-related factors, including alpha-smooth muscle actin, transforming growth factor-beta 1, matrix metalloproteinase-2, and collagen type I, were increased after MI. TFR treatment attenuated the upregulation of these factors, downregulated UTR expression, and markedly diminished the expression of RhoA and ROCK1/2. These results suggested that TFR could improve cardiac function and ameliorate ventricular remodeling through blocking UTR-mediated activation of RhoA-ROCK pathways in myocardial infarction rats.

Selective inhibition of brain endothelial Rho-kinase-2 provides optimal protection of an in vitro blood-brain barrier from tissue-type plasminogen activator and plasmin

Rho-kinase (ROCK) inhibition, broadly utilised in cardiovascular disease, may protect the blood-brain barrier (BBB) during thrombolysis from rt-PA-induced damage. While the use of nonselective ROCK inhibitors like fasudil together with rt-PA may be hindered by possible hypotensive side-effects and inadequate capacity to block detrimental rt-PA activity in brain endothelial cells (BECs), selective ROCK-2 inhibition may overcome these limitations. Here, we examined ROCK-2 expression in major brain cells and compared the ability of fasudil and KD025, a selective ROCK-2 inhibitor, to attenuate rt-PA-induced BBB impairment in an in vitro human model. ROCK-2 was highly expressed relative to ROCK-1 in all human and mouse brain cell types and particularly enriched in rodent brain endothelial cells and astrocytes compared to neurons. KD025 was more potent than fasudil in attenuation of rt-PA- and plasminogen-induced BBB permeation under normoxia, but especially under stroke-like conditions. Importantly, only KD025, but not fasudil, was able to block rt-PA-dependent permeability increases, morphology changes and tight junction degradation in isolated BECs. Selective ROCK-2 inhibition further diminished rt-PA-triggered myosin phosphorylation, shape alterations and matrix metalloprotease activation in astrocytes. These findings highlight ROCK-2 as the key isoform driving BBB impairment and brain endothelial damage by rt-PA and the potential of KD025 to optimally protect the BBB during thrombolysis.

Membrane depolarization activates BK channels through ROCK-mediated β1 subunit surface trafficking to limit vasoconstriction

Membrane depolarization of smooth muscle cells (myocytes) in the small arteries that regulate regional organ blood flow leads to vasoconstriction. Membrane depolarization also activates large-conductance calcium (Ca²⁺)-activated potassium (BK) channels, which limits Ca²⁺ channel activity that promotes vasoconstriction, thus leading to vasodilation. We showed that in human and rat arterial myocytes, membrane depolarization rapidly increased the cell surface abundance of auxiliary BK β1 subunits but not that of the pore-forming BKα channels. Membrane depolarization stimulated voltage-dependent Ca²⁺ channels, leading to Ca²⁺ influx and the activation of Rho kinase (ROCK) 1 and 2. ROCK1/2-mediated activation of Rab11A promoted the delivery of β1 subunits to the plasma membrane by Rab11A-positive recycling endosomes. These additional β1 subunits associated with BKα channels already at the plasma membrane, leading to an increase in apparent Ca²⁺ sensitivity and activation of the channels in pressurized arterial myocytes and vasodilation. Thus, membrane depolarization activates BK channels through stimulation of ROCK- and Rab11A-dependent trafficking of β1 subunits to the surface of arterial myocytes.

The Role of Rho/Rho-Kinase Pathway in the Pathogenesis of Cholesteatoma

OBJECTIVE

To assess the role of Rho/Rho-kinase pathway in the pathogenesis of cholesteatoma.

MATERIALS AND METHODS

Thirty-eight patients with cholesteatoma, who had gone mastoidectomies were enrolled in this prospective study. Cholesteatomas matrix (CM) and a piece of the external ear canal skin (EECS as control) were taken and transferred to the liquid nitrogen and kept at -86 °C for Rho A and Rho-kinase (ROCK) analysis with Western blotting and commercial ELISA kits (Cell Biolabs Inc., San Diego, CA). The tissues were homogenized by an appropriate ice-cold lysis buffer. Following centrifugation, the supernatant was taken and total protein amount was detected by the Bradford method. Thereafter, tissue homogenates were subjected to sodium dodecyl sulphate (SDS)-polyacrylamide gel electrophoresis electrophoresis then transferred to nitrocellulose membrane where it was treated with specific monoclonal primary antibody against to ROCK-2 and HRP-conjugated seconder antibody, respectively. The protein blots were visualized with commercial x-ray film and dansitometrically analyzed by the Scion Image Program (Cell Biolabs Inc., San Diego, CA). In another series of experiments, Rho-kinase activities were assessed by ROCK-2 ELISA kits.

RESULTS

There were no statistical differences in Rho A translocation between CM and EECS. However, ROCK activity was found to be lower in CM than EECS as detected by ELISA kits. Furthermore, ROCK protein expression was also significantly lower in CM than EECS as demonstrated by Western blotting.

CONCLUSION

Given Rho-kinase could take essential roles in cell differentiation, the results of this study implicate that down-regulated Rho-kinase could be responsible for the keratinocyte undifferentiation seen in cholesteatoma pathogenesis.

Fn14 is regulated via the RhoA pathway and mediates nuclear factor-kappaB activation by Angiotensin II

Angiotesin II (Ang II) plays an important role in cardiac remodeling. Fibroblast growth factor inducible-14 (Fn14) is the smallest member of the tumor necrosis factor superfamily of receptors. Currently, little is known about the functional role of Fn14 in the heart. Chiefly, we observe the up-regulation of extracellular matrix in in vivo model. We therefore assess the expression and regulation of Fn14 in cardiomyocytes and in vivo models induced by Ang II. In order to study the regulation of Fn14, cardiac remodeling was established in rats and neonatal cardiomyocytes were used in in vitro model. As well, Ang II is able to strongly induce Fn14 expression in in vivo and in vitro models. Fn14 is mediated via RhoA pathways, since siRNA against RhoA prevented the expression of Fn14 in cardiomyocytes. Pretreatment of cardiomyoctes with siRNA against NF-κB and IκBα also decreased Fn14 expression induced by Ang II. We here describe for the first time Ang II regulation of Fn14 in in vivo and in vitro models via RhoA, NF-κB and NF-κB driven gene signaling pathway. In conclusion, Fn14 may be important in regulating the process of cardiac remodeling induced by Ang II.

Regulation of pulmonary endothelial barrier function by kinases

The pulmonary endothelium is the target of continuous physiological and pathological stimuli that affect its crucial barrier function. The regulation, defense, and repair of endothelial barrier function require complex biochemical processes. This review examines the role of endothelial phosphorylating enzymes, kinases, a class with profound, interdigitating influences on endothelial permeability and lung function.

Role of the Rho GTPase/Rho kinase signaling pathway in pathogenesis and treatment of glaucoma: Bench to bedside research

Glaucoma is a leading cause of irreversible blindness worldwide. Elevated intraocular pressure (IOP) is considered to be a predominant risk factor for primary open angle glaucoma, the most prevalent form of glaucoma. Although the etiological mechanisms responsible for increased IOP are not completely clear, impairment in aqueous humor (AH) drainage through the conventional or trabecular pathway is recognized to be a primary cause in glaucoma patients. Importantly, lowering of IOP has been demonstrated to reduce progression of vision loss and is a mainstay of treatment for all types of glaucoma. Currently however, there are limited therapeutic options available for lowering IOP especially as it relates to enhancement of AH outflow through the trabecular pathway. Towards addressing this challenge, bench and bedside research conducted over the course of the last decade and a half has identified the significance of inhibiting Rho kinase for lowering IOP. Rho kinase is a downstream effector of Rho GTPase signaling that regulates actomyosin dynamics in numerous cell types. Studies from several laboratories have demonstrated that inhibition of Rho kinase lowers IOP via relaxation of the trabecular meshwork which enhances AH outflow. By contrast, activation of Rho GTPase/Rho kinase signaling in the trabecular outflow pathway increases IOP by altering the contractile, cell adhesive and permeability barrier characteristics of the trabecular meshwork and Schlemm's canal tissues, and by influencing extracellular matrix production and fibrotic activity. This article, written in honor of the late David Epstein, MD, summarizes findings from both basic and clinical studies that have been instrumental for recognition of the importance of the Rho/Rho kinase signaling pathway in regulation of AH outflow, and in the development of Rho kinase inhibitors as promising IOP- lowering agents for glaucoma treatment.

Progress on the cardiotoxicity of sunitinib: Prognostic significance, mechanism and protective therapies

Tyrosine kinase inhibitors (TKIs) are multi-targeted anti-cancer agents effective in the treatment of renal cell carcinoma (RCC), imatinib-resistant gastrointestinal stromal tumor (GIST) and pancreatic cancer (PC). Targeting and inhibiting a wide range of oncogenically relevant receptor tyrosine kinases (RTKs), TKIs have been the golden standard treatment of several types of cancer. The cardiotoxicity of TKIs, however, has also emerged alongside their anti-cancer potencies and has attracted research attention. Over the past few years significant progress has been made in developing a deeper understanding of aspects such as extent of cardiotoxicity, prognostic implications and survival predictions, toxicological mechanisms, and potential cardioprotective therapies. In this review we focus on a typical TKI sunitinib and summarize the up-to-date knowledge of sunitinib-induced cardiac abnormalities reported in clinical studies, weighing their implications of prognostic values. We also examine recent findings in underlying mechanisms, and development of potential cardioprotective agents.

The effects of ripasudil (K-115), a Rho kinase inhibitor, on activation of human conjunctival fibroblasts

The most common cause of glaucoma surgery failure is scar formation induced by activation of wound-healing responses and resultant fibrosis at the surgical site. We investigated the effects of ripasudil, a Rho kinase inhibitor, on activation of human conjunctival fibroblasts (HConF). HConF were pretreated with different concentrations of ripasudil for 1 h before addition of transforming growth factor (TGF)-β2, followed by incubation for 48 h. TGF-β2-treated fibroblasts exhibited a significant increase in expression of α-smooth muscle actin (α-SMA), a marker of fibroblast-to-myofibroblast differentiation, and this increase was significantly suppressed, in a dose-dependent manner, by pretreatment with ripasudil. Ripasudil pretreatment also significantly attenuated TGF-β2-induced fibronectin production and collagen gel contraction. TGF-β2 increased both the number of viable cells and the number of cells in the G2/M phase of the cell cycle; these effects were attenuated by pretreatment with ripasudil. In addition, we explored the effects of ripasudil on stimulation of HConF by activated macrophages. Human monocytic cell line THP-1 cells were differentiated into M1 or M2 macrophage-like cells, and HConF were treated with conditioned media derived from these macrophages in the presence or absence of ripasudil. Conditioned medium from M2 macrophage-like cells induced a significant increase in α-SMA expression, viable cell numbers, and gel contraction, all of which were significantly suppressed by ripasudil. Thus, overall, ripasudil attenuated activation of human conjunctival fibroblasts. Ripasudil may be of therapeutic utility, preventing excessive scarring after glaucoma filtration surgery.

Focused Proteomics Revealed a Novel Rho-kinase Signaling Pathway in the Heart

Protein phosphorylation plays an important role in the physiological regulation of cardiac function. Myocardial contraction and pathogenesis of cardiac diseases have been reported to be associated with adaptive or maladaptive protein phosphorylation; however, phosphorylation signaling in the heart is not fully elucidated. We recently developed a novel kinase-interacting substrate screening (KISS) method for exhaustive screening of protein kinase substrates, using mass spectrometry and affinity chromatography. First, we examined protein phosphorylation by extracellular signal-regulated kinase (ERK) and protein kinase A (PKA), which has been relatively well studied in cardiomyocytes. The KISS method showed that ERK and PKA mediated the phosphorylation of known cardiac-substrates of each kinase such as Rps6ka1 and cTnI, respectively. Using this method, we found about 330 proteins as Rho-kinase-mediated substrates, whose substrate in cardiomyocytes is unknown. Among them, CARP/Ankrd1, a muscle ankyrin repeat protein, was confirmed as a novel Rho-kinase-mediated substrate. We also found that non-phosphorylatable form of CARP repressed cardiac hypertrophy-related gene Myosin light chain-2v (MLC-2v) promoter activity, and decreased cell size of heart derived H9c2 myoblasts more efficiently than wild type-CARP. Thus, focused proteomics enable us to reveal a novel signaling pathway in the heart.

The cytoskeleton as a novel target for treatment of renal fibrosis

The incidence of chronic kidney disease (CKD) is increasing, with an estimated prevalence of 12% in the United States (Synder et al., 2009). While CKD may progress to end-stage renal disease (ESRD), which necessitates renal replacement therapy, i.e. dialysis or transplantation, most CKD patients never reach ESRD due to the increased risk of death from cardiovascular disease. It is well-established that regardless of the initiating insult - most often diabetes or hypertension - fibrosis is the common pathogenic pathway that leads to progressive injury and organ dysfunction (Eddy, 2014; Duffield, 2014). As such, there has been extensive research into the molecular and cellular mechanisms of renal fibrosis; however, translation to effective therapeutic strategies has been limited. While a role for the disruption of the cytoskeleton, most notably the actin network, has been established in acute kidney injury over the past two decades, a role in regulating renal fibrosis and CKD is only recently emerging. This review will focus on the role of the cytoskeleton in regulating pro-fibrotic pathways in the kidney, as well as data suggesting that these pathways represent novel therapeutic targets to manage fibrosis and ultimately CKD.

Simultaneous Rho kinase inhibition in circulating leukocytes and in cardiovascular tissue in rats with high angiotensin converting enzyme levels

BACKGROUND

The small guanosine triphosphatase RhoA and its direct target Rho kinase (ROCK) play important roles in cardiovascular pathophysiology. Activated ROCK phosphorylates intracellular proteins with detrimental effects on cardiovascular remodeling. Increased ROCK activity in circulating leukocytes is observed in hypertension and in heart failure, but its relationship with ROCK activation in the myocardium and vessels is unknown. We hypothesized that ROCK activation and phosphorylation/activation of some of its key downstream molecules in the heart and arterial wall are reflected in circulating leukocytes.

METHODS

Phosphorylation of MYPT1, ERM and p38-MAPK and levels of p65-NF-κB were determined in the left ventricle (LV), aortic wall and circulating leukocytes in rats with high (Brown Norway, BN) and low (Lewis) angiotensin converting enzyme. A group of BN rats received the ROCK inhibitor fasudil (7days).

RESULTS

Compared to Lewis rats, in the BN group phosphorylated levels of MYPT1, ERM and p38-MAPK and levels of p65-NF-κB were increased (P<0.05) in the LV (67%, 92%, 52% and 98%, respectively); in the aortic wall (57%, 51%, 68% and 66%, respectively) and in circulating leukocytes (61%, 72%, 49% and 105%, respectively). Fasudil reduced all these levels to those observed in Lewis rats. Phosphorylated MYPT1, ERM, and p38-MAPK and levels of p65-NF-κB in circulating leukocytes were significantly correlated with their respective LV and aortic wall levels (excepting p65-NF-κB in aorta).

CONCLUSION

ROCK activity in circulating leukocytes reflects activation of this signaling pathway in the myocardium and aortic wall in this model, and supports its value as a potential cardiovascular remodeling marker.