Association analysis of polymorphisms in ROCK2 with cardiovascular disease in a Chinese population

Druggable targets in the Rho pathway and their promise for therapeutic control of blood pressure

The prevalence of high blood pressure (also known as hypertension) has steadily increased over the last few decades. Known as a silent killer, hypertension increases the risk for cardiovascular disease and can lead to stroke, heart attack, kidney failure and associated sequela. While numerous hypertensive therapies are currently available, it is estimated that only half of medicated patients exhibit blood pressure control. This signifies the need for a better understanding of the underlying cause of disease and for more effective therapies. While blood pressure homeostasis is very complex and involves the integrated control of multiple body systems, smooth muscle contractility and arterial resistance are important contributors. Strong evidence from pre-clinical animal models and genome-wide association studies indicate that smooth muscle contraction and BP homeostasis are governed by the small GTPase RhoA and its downstream target, Rho kinase. In this review, we summarize the signaling pathways and regulators that impart tight spatial-temporal control of RhoA activity in smooth muscle cells and discuss current therapeutic strategies to target these RhoA pathway components. We also discuss known allelic variations in the RhoA pathway and consider how these polymorphisms may affect genetic risk for hypertension and its clinical manifestations.

Exposure to endosulfan increases endothelial permeability by transcellular and paracellular pathways in relation to cardiovascular diseases

Exposure to environmental pollutants results in out-of-balance of vascular homeostasis. Endothelial dysfunction leads to a disruption of the endothelial permeability characteristics, associated with cardiovascular diseases. We previously reported that endosulfan could cause endothelial dysfunction, but the role of endosulfan in permeability of endothelial cells has been unexplored. To elucidate molecular mechanism of endosulfan-induced changes in endothelial permeability, human umbilical vein endothelial cells (HUVECs) were exposed to endosulfan, followed by endothelial permeability analysis. The results showed that permeability of HUVECs was enhanced at 48 h after exposure to endosulfan in a dose-dependent manner. Immunofluorescence analysis demonstrated the disruptions of actin cytoskeleton and focal adhesion in endosulfan-exposed cells. Endosulfan activated MMP3/LAMC1/FAK signaling pathway, and downregulated ROCK and PXN in transcellular pathway. Endosulfan affected adherens junctions via E-cadherin and β-catenin, and impaired gap junctions through downregulation of Cx43 in paracellular pathway. We predicted four closely related human cardiovascular diseases in Nextbio, including shock, coronary arteriosclerosis, disorder of cardiac function and hypertensive disorder in relation to endosulfan exposure. Some genes such as ROCK2 and PXN were predicted to be key genes in these diseases. These findings suggest that endosulfan increased endothelial permeability by paracellular and transcellular pathways, implicating the potential correlation between endosulfan and cardiovascular diseases.

RhoA signaling and blood pressure: The consequence of failing to “Tone it Down”

Uncontrolled high blood pressure is a major risk factor for heart attack, stroke, and kidney failure and contributes to an estimated 25% of deaths worldwide. Despite numerous treatment options, estimates project that reasonable blood pressure (BP) control is achieved in only about half of hypertensive patients. Improvements in the detection and management of hypertension will undoubtedly be accomplished through a better understanding of the complex etiology of this disease and a more comprehensive inventory of the genes and genetic variants that influence BP regulation. Recent studies (primarily in pre-clinical models) indicate that the small GTPase RhoA and its downstream target, Rho kinase, play an important role in regulating BP homeostasis. Herein, we summarize the underlying mechanisms and highlight signaling pathways and regulators that impart tight spatial-temporal control of RhoA activity. We also discuss known allelic variations in the RhoA pathway and consider how these polymorphisms may affect genetic risk for hypertension and its clinical manifestations. Finally, we summarize the current (albeit limited) clinical data on the efficacy of targeting the RhoA pathway in hypertensive patients.

Polymorphisms and haplotype of ROCK2 associate with high altitude essential hypertension in native high altitude Ladakhi Indian population: a preliminary study

BACKGROUND AND OBJECTIVES

High-altitude essential hypertension (HAEH) is a disease occurring in permanent residents of high-altitude regions. The disease is characterized with SBP ≥140 mmHg and DBP ≥90 mmHg. HAEH is known to run in families, i.e. the disease has genetic component. Rho-associated coiled-coil containing protein kinase 2 (ROCK2) is a stress-activated serine-threonine kinase known to disturb vascular-homeostasis leading to an increase in systemic vascular resistance, hallmark of HAEH. ROCK2 is implicated in sea-level essential hypertension but its role in HAEH is yet to be elucidated.

METHODS

The present study deals with genotyping 13 polymorphisms of ROCK2 gene in demographicaly matched human cases (n = 65) and controls (n = 38) by Sequenom MS (TOF)-based MassARRAY platform using iPLEX Gold technology.

RESULTS

A significant association was observed for GG genotype (SNP, rs978906), AA genotype (SNP, rs6753921), GG genotype (SNP, rs10495582) and AA genotype (SNP, rs2230774) with HAEH (p < 0.05). The 4 SNPs were tagged to each other and formed a 35 kb LD block (r(2 )> 0.90). Haplotype AGCC, composed of wild-type alleles of the SNPs was over represented in controls. In contrast, haplotype GAGA, composed of variant-alleles was observed to be in higher proportion in cases. Moreover, SBP levels (mmHg) were higher in cases with risk genotype against the ones having protective genotype (p = 0.05). Bioinformatic analysis revealed binding of a critical transcription factor, SRF to variant-allele G of SNP rs10495582. SRF has been reported in previous studies to promote ROCK2 transcriptional expression.

INTERPRETATION AND CONCLUSIONS

The data clearly suggests association of ROCK2 polymorphisms and haplotypes with HAEH.

Rho Kinases in Health and Disease: From Basic Science to Translational Research

Rho-associated kinases ROCK1 and ROCK2 are key regulators of actin cytoskeleton dynamics downstream of Rho GTPases that participate in the control of important physiologic functions, S including cell contraction, migration, proliferation, adhesion, and inflammation. Several excellent review articles dealing with ROCK function and regulation have been published over the past few years. Although a brief overview of general molecular, biochemical, and functional properties of ROCKs is included, an effort has been made to produce an original work by collecting and synthesizing recent studies aimed at translating basic discoveries from cell and experimental models into knowledge of human physiology, pathophysiological mechanisms, and medical therapeutics. This review points out the specificity and distinct roles of ROCK1 and ROCK2 isoforms highlighted in the last few years. Results obtained from genetically modified mice and genetic analysis in humans are discussed. This review also addresses the involvement of ROCKs in human diseases and the potential use of ROCK activity as a biomarker or a pharmacological target for specific inhibitors.

ADAMTS7 locus confers high cross-race risk for development of coronary atheromatous plaque

Genome-wide association studies of coronary artery disease (CAD) have recently identified a new susceptibility locus, ADAMTS7, in subjects of European ancestry. However, the significance of this locus in Chinese populations has not been identified. Therefore, this study was designed to evaluate the effect of rs3825807, a non-synonymous variant in the prodomain of the ADAMTS7 protease, on CAD risk and atherosclerosis severity in a Chinese population. We performed genetic association analyses in two independent case-control cohorts, which included a total of 8154 participants. Additionally, the association between the ADAMTS7 rs3825807 genotype and the proportion of CAD patients with 3- and 1-vessel disease was tested. We found that ADAMTS7 rs3825807 was associated with susceptibility to CAD in a Chinese population [odds ratio (OR) = 1.15, 95 % confidence interval (CI) = 1.05-1.26, P = 0.002]. The association remained significant after adjusting for clinical covariates (adjusted OR = 1.12, 95 % CI = 1.02-1.24, P = 0.02). Among 3741 angiographically documented CAD patients, the rs3825807 risk allele showed a significant association with disease severity (P = 0.04, trend P = 0.02). Additionally, 3-vessel disease demonstrated a strong and direct association with ADAMTS7 rs3825807 gene dosage (P = 0.02). Overall, our findings indicate that the significant associations observed between this coding variant in ADAMTS7 and the risk of CAD development are cross-ethnic, and the gene dosage is consistent with the degree of coronary atheromatous burden.

Genetic insight into the role of MRAS in coronary artery disease risk

The muscle Ras (MRAS) gene polymorphisms have been reported to be associated with coronary artery disease (CAD) in white Europeans. The aim of this study was to ascertain the role of MRAS gene polymorphisms in conferring susceptibility to CAD, and to explore the effect on severity of CAD in Chinese population. We genotyped 5009 Chinese individuals (2466 CAD cases and 2543 controls) for eight single nucleotide polymorphisms (SNPs) around MRAS and used logistic regression analysis to determine whether they were associated with CAD. The association of the SNP loci on the severity of CAD was analyzed using a logistic and linear regression analysis, respectively. Our results revealed that an intron SNP, rs1199337, tends to be marginally associated with CAD as previously reported in Caucasians (nominal P=0.01, OR 1.10, 95% CI 1.01-1.20). However, this association did not retain statistically significant levels after applying Bonferroni's correction for multiple testing (corrected P=0.08). There was no significant association between other loci and CAD (nominal P>0.05). We did not observe any significant association between the SNPs and severity of CAD (all P values>0.05). From the above results, the MRAS gene loci might have a minor effect in conferring susceptibility to CAD in Chinese population.

Two functional polymorphisms of ROCK2 enhance arterial stiffening through inhibiting its activity and expression

Derangement of Rho-associated kinases (ROCKs) has been related to coronary artery disease and stroke. ROCK2, rather than ROCK1, plays a predominant role in vascular contractility. The present study aims to test (1) the associations between ROCK2 single nucleotide polymorphisms (SNPs) and arterial stiffness, and (2) the molecular mechanism accounting for their effects. Stiffness parameters including beta (β), elasticity modulus (Ep) and pulse wave velocity (PWV) were obtained by carotid ultrasonography. Seven tagging SNPs of ROCK2 were initially genotyped in 856 subjects and significant SNPs were replicated in another group of 527 subjects. Two SNPs in complete linkage disequilibrium were found to be significantly associated with arterial stiffness. The major alleles of rs978906 (A allele) and rs9808232 (C allele) were associated with stiffer arteries. SNP rs978906 was predicted to influence microRNA(miR)-1183 binding to ROCK2, while rs9808232 causes amino acid substitution. To determine their functional impact, plasmid constructs carrying different alleles of the significant SNPs were created. Compared to rs978906G-allele constructs, cells transfected with rs978906A-allele constructs had higher baseline luciferase activities and were less responsive to miR-1183 changes. Oxidized-low density lipoprotein (Ox-LDL) suppressed miR-1183 levels and increased ROCK2 protein amounts. For rs9808232, cells transfected with C-allele constructs had significantly higher ROCK activities than those with A-allele constructs. Leukocyte ROCK activities were further measured in 52 healthy subjects. The average ROCK activity was highest in human subjects with CC genotype at rs9808232, followed by those with AC and lowest in AA. Taken together, the present study showed that two functional SNPs of ROCK2 increase susceptibility of arterial stiffness in the Chinese population. Non-synonymous SNP rs9808232 influences ROCK2 activity, while 3' UTR SNP rs978906 affects the ROCK2 protein synthesis by interfering miR-1183 binding.

Involvement of Rho GTPases and their regulators in the pathogenesis of hypertension

Proper regulation of arterial blood pressure is essential to allow permanent adjustment of nutrient and oxygen supply to organs and tissues according to their need. This is achieved through highly coordinated regulation processes controlling vascular resistance through modulation of arterial smooth muscle contraction, cardiac output, and kidney function. Members of the Rho family of small GTPases, in particular RhoA and Rac1, have been identified as key signaling molecules playing important roles in several different steps of these regulatory processes. Here, we review the current state of knowledge regarding the involvement of Rho GTPase signaling in the control of blood pressure and the pathogenesis of hypertension. We describe how knockout models in mouse, genetic, and pharmacological studies in human have been useful to address this question.