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Different roles of myocardial ROCK1 and ROCK2 in cardiac dysfunction and postcapillary pulmonary hypertension in mice.

ABSTRACT: Although postcapillary pulmonary hypertension (PH) is an important prognostic factor for patients with heart failure (HF), its pathogenesis remains to be fully elucidated. To elucidate the different roles of Rho-kinase isoforms, ROCK1 and ROCK2, in cardiomyocytes in response to chronic pressure overload, we performed transverse aortic constriction (TAC) in cardiac-specific ROCK1-deficient (cROCK1^-/-) and ROCK2-deficient (cROCK2^-/-) mice. Cardiomyocyte-specific ROCK1 deficiency promoted pressure-overload-induced cardiac dysfunction and postcapillary PH, whereas cardiomyocyte-specific ROCK2 deficiency showed opposite results. Histological analysis showed that pressure-overload-induced cardiac hypertrophy and fibrosis were enhanced in cROCK1^-/- mice compared with controls, whereas cardiac hypertrophy was attenuated in cROCK2^-/- mice after TAC. Consistently, the levels of oxidative stress were up-regulated in cROCK1^-/- hearts and down-regulated in cROCK2^-/- hearts compared with controls after TAC. Furthermore, cyclophilin A (CyPA) and basigin (Bsg), both of which augment oxidative stress, enhanced cardiac dysfunction and postcapillary PH in cROCK1^-/- mice, whereas their expressions were significantly lower in cROCK2^-/- mice. In clinical studies, plasma levels of CyPA were significantly increased in HF patients and were higher in patients with postcapillary PH compared with those without it. Finally, high-throughput screening demonstrated that celastrol, an antioxidant and antiinflammatory agent, reduced the expressions of CyPA and Bsg in the heart and the lung, ameliorating cardiac dysfunction and postcapillary PH induced by TAC. Thus, by differentially affecting CyPA and Bsg expressions, ROCK1 protects and ROCK2 jeopardizes the heart from pressure-overload HF with postcapillary PH, for which celastrol may be a promising agent.

SUBMITTER: Sunamura S

PROVIDER: S-EPMC6064988 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:Progressive cardiac fibrosis is a common cause of heart failure. Rho-associated, coiled-coil-containing protein kinases (ROCKs) have been shown to enhance fibrotic processes in the heart and in other organs. In this study, using wild-type, Rock1+/- and Rock2+/- haploinsufficient mice and mouse model of experimental autoimmune myocarditis (EAM) we addressed the role of ROCK1 and ROCK2 in development of myocarditis and postinflammatory fibrosis. We found that myocarditis severity was comparable in wild-type, Rock1+/- and Rock2+/- mice at day 21 of EAM. During the acute stage of the disease, hearts of Rock1+/- mice showed unaffected numbers of CD11b+CD36+ macrophages, CD11b+CD36-Ly6GhiLy6chi neutrophils, CD11b+CD36-Ly6G-Ly6chi inflammatory monocytes, CD11b+CD36-Ly6G-Ly6c- monocytes, CD11b+SiglecF+ eosinophils, CD11b+CD11c+ inflammatory dendritic cells and type I collagen-producing fibroblasts. Isolated Rock1+/- cardiac fibroblasts treated with transforming growth factor-beta (TGF-β) showed attenuated Smad2 and extracellular signal-regulated kinase (Erk) phosphorylations that were associated with impaired upregulation of smooth muscle actin alpha (αSMA) protein. In contrast to cardiac fibroblasts, expanded Rock1+/- heart inflammatory myeloid cells showed unaffected Smad2 activation but enhanced Erk phosphorylation following TGF-β treatment. Rock1+/- inflammatory cells responded to TGF-β by a reduced transcriptional profibrotic response and failed to upregulate αSMA and fibronectin at the protein levels. Unexpectedly, in the EAM model wild-type, Rock1+/- and Rock2+/- mice developed a similar extent of cardiac fibrosis at day 40. In addition, hearts of the wild-type and Rock1+/- mice showed comparable levels of cardiac vimentin, periostin and αSMA. In conclusion, despite the fact that ROCK1 regulates TGF-β-dependent profibrotic response, neither ROCK1 nor ROCK2 is critically involved in the development of postinflammatory fibrosis in the EAM model.

Project description:In male mice, sepsis-induced cardiomyopathy develops as a result of dysregulation of myocardial calcium (Ca) handling, leading to depressed cellular Ca transients (?Cai). ?Cai depression is partially due to inhibition of sarcoplasmic reticulum Ca ATP-ase (SERCA) via oxidative modifications, which are partially opposed by cGMP generated by the enzyme soluble guanylyl cyclase (sGC). Whether similar mechanisms underlie sepsis-induced cardiomyopathy in female mice is unknown.Male and female C57Bl/6J mice (WT), and mice deficient in the sGC ?1 subunit activity (sGC?1), were challenged with lipopolysaccharide (LPS, ip). LPS induced mouse death and cardiomyopathy (manifested as the depression of left ventricular ejection fraction by echocardiography) to a similar degree in WT male, WT female, and sGC?1 male mice, but significantly less in sGC?1 female mice. We measured sarcomere shortening and ?Cai in isolated, externally paced cardiomyocytes, at 37°C. LPS depressed sarcomere shortening in both WT male and female mice. Consistent with previous findings, in male mice, LPS induced a decrease in ?Cai (to 30?±?2% of baseline) and SERCA inhibition (manifested as the prolongation of the time constant of Ca decay, ?Ca, to 150?±?5% of baseline). In contrast, in female mice, the depression of sarcomere shortening induced by LPS occurred in the absence of any change in ?Cai, or SERCA activity. This suggested that, in female mice, the causative mechanism lies downstream of the Ca transients, such as a decrease in myofilament sensitivity for Ca. The depression of sarcomere shortening shortening after LPS was less severe in female sGC?1 mice than in WT female mice, indicating that cGMP partially mediates cardiomyocyte dysfunction.These results suggest, therefore, that LPS-induced cardiomyopathy develops through distinct sex-specific myocardial mechanisms. While in males LPS induces sGC-independent decrease in ?Cai, in female mice LPS acts downstream of ?Cai, possibly via sGC-dependent myofilament dysfunction.

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Different roles of myocardial ROCK1 and ROCK2 in cardiac dysfunction and postcapillary pulmonary hypertension in mice.

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