Fibroblast deletion of ROCK2 attenuates cardiac hypertrophy, fibrosis, and diastolic dysfunction
Toru Shimizu, … , John Blair, James K. Liao
Toru Shimizu, … , John Blair, James K. Liao
Published July 6, 2017
Citation Information: JCI Insight. 2017;2(13):e93187. https://doi.org/10.1172/jci.insight.93187.
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Research Article Cardiology

Fibroblast deletion of ROCK2 attenuates cardiac hypertrophy, fibrosis, and diastolic dysfunction

Abstract

Although left ventricular (LV) diastolic dysfunction is often associated with hypertension, little is known regarding its underlying pathophysiological mechanism. Here, we show that the actin cytoskeletal regulator, Rho-associated coiled-coil containing kinase-2 (ROCK2), is a critical mediator of LV diastolic dysfunction. In response to angiotensin II (Ang II), mutant mice with fibroblast-specific deletion of ROCK2 (ROCK2Postn–/–) developed less LV wall thickness and fibrosis, along with improved isovolumetric relaxation. This corresponded with decreased connective tissue growth factor (CTGF) and fibroblast growth factor–2 (FGF2) expression in the hearts of ROCK2Postn–/– mice. Indeed, knockdown of ROCK2 in cardiac fibroblasts leads to decreased expression of CTGF and secretion of FGF2, and cardiomyocytes incubated with conditioned media from ROCK2-knockdown cardiac fibroblasts exhibited less hypertrophic response. In contrast, mutant mice with elevated fibroblast ROCK activity exhibited enhanced Ang II–stimulated cardiac hypertrophy and fibrosis. Clinically, higher leukocyte ROCK2 activity was observed in patients with diastolic dysfunction compared with age- and sex-matched controls, and correlated with higher grades of diastolic dysfunction by echocardiography. These findings indicate that fibroblast ROCK2 is necessary to cause cardiac hypertrophy and fibrosis through the induction CTGF and FGF2, and they suggest that targeting ROCK2 may have therapeutic benefits in patients with LV diastolic dysfunction.

Authors

Toru Shimizu, Nikhil Narang, Phetcharat Chen, Brian Yu, Maura Knapp, Jyothi Janardanan, John Blair, James K. Liao

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Figure 7

Effects of ROCK deletion on mRNA expression of FGF2, CTGF, and α-SMA in response to angiotensin II (Ang II) or transforming growth factor-β1 (TGF-β1) in mouse embryonic fibroblasts (MEFs).

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Effects of ROCK deletion on mRNA expression of FGF2, CTGF, and α-SMA in ...
(A–C) Quantitative PCR analysis of Fgf2 (encoding fibroblast growth factor 2), Ctgf (connective tissue growth factor), and Acta2 (α-smooth muscle actin) mRNA expression stimulated by 1 μM Ang II or 10 ng/ml TGF-β1 for 24 hours, with or without 10 μM Y27632, a specific ROCK inhibitor, in MEFs isolated from WT (n = 3–4 each). **P < 0.01 vs. vehicle-stimulated WT MEFs. #P < 0.05, ##P < 0.01 vs. the same stimulated WT MEFs without Y27632. †P < 0.05, ††P < 0.01 vs. Ang II–stimulated WT MEFs without Y27632. (D–F) Quantitative PCR analysis of Fgf2, Ctgf, and Acta2 mRNA expression stimulated by 1 μM Ang II or 10 ng/ml TGF-β1 for 24 hours in MEFs isolated from WT, global Rock1-KO (ROCK1–/–), and global Rock2-KO (ROCK2–/–) mice (n = 3–4 each). *P < 0.01, **P < 0.01 vs. vehicle-stimulated WT MEFs. #P < 0.05, ##P < 0.01 vs. the same stimulated WT MEFs. †P < 0.05, ††P < 0.01 vs. Ang II–stimulated WT MEFs. ‡P < 0.05 vs. TGF-β1–stimulated global ROCK1–/– MEFs. Data are expressed as mean ± SEM. P values were calculated using one-way ANOVA with Tukey’s HSD test.