rottlerin and Fibrosis

Relaxin (Rlx) is known to antagonize diabetic cardiac fibrosis. However, its mechanism is poorly understood. Protein kinase Cδ (PKCδ) plays a crucial role in diabetic cardiomyopathy (DCM). This study explored the involvement of PKCδ in Rlx's capacity of suppressing cardiac fibrosis in a rat model of type 2 diabetes mellitus (DM). Type 2 DM of 8-week-old male Sprague-Dawley (SD) rats was induced by a high-fat diet and the injection of streptozocin (STZ, 40 mg/kg). Fourteen-week-old rats with DM and rats in control group which were pre-treated for 1 week with human recombinant relaxin (rhRlx, 30 μg/kg.d), were assessed to detect cardiac fibrosis and PKCδ expression with Western blot. Cardiac fibroblasts of neonatal rats were treated for 72 h with rhRlx (100 ng/ml) under high glucose (HG). Western blot was utilized for detecting the membranous and cytoplasmic protein expressions of PKCδ. The effects of rhRlx and PKCδ inhibitor (rottlerin) were assessed either alone or in combination on the HG-induced proliferation and differentiation of cardiac fibroblasts and the release of collagen I.Rlx treatment inhibited the differentiation of cardiac fibroblasts and the expression of collagen I. The expression of PKCδ was regulated by Rlx in diabetic rats and cardiac fibroblasts under HG condition. The effects of Rlx upon the proliferation and differentiation of cardiac fibroblasts and the excretion of collagen I under HG were blunted by rottlerin. Rlx suppressed cardiac fibrosis in type 2 diabetic rats. This beneficial effect was associated with its ability of modulating the expression of PKCδ.

Topics: Acetophenones; Animals; Animals, Newborn; Benzopyrans; Diabetes Mellitus, Experimental; Diabetes Mellitus, Type 2; Diabetic Cardiomyopathies; Disease Models, Animal; Enzyme Inhibitors; Fibroblasts; Fibrosis; Humans; Male; Myocardium; Protein Kinase C-delta; Rats; Rats, Sprague-Dawley; Recombinant Proteins; Relaxin

Previous studies have demonstrated a role for angiotensin II (AngII) and myofibroblasts (myoFb) in cardiac fibrosis. However, the role of PKC-delta in AngII mediated cardiac fibrosis is unclear. Therefore, the present study was designed to investigate the role of PKC-delta in AngII induced cardiac collagen expression and fibrosis. AngII treatment significantly (p<0.05) increased myoFb collagen expression, whereas PKC-delta siRNA treatment or rottlerin, a PKC-delta inhibitor abrogated (p<0.05) AngII induced collagen expression. MyoFb transfected with PKC-delta over expression vector showed significant increase (p<0.05) in the collagen expression as compared to control. Two weeks of chronic AngII infused rats showed significant (p<0.05) increase in collagen expression compared to sham operated rats. This increase in cardiac collagen expression was abrogated by rottlerin treatment. In conclusion, both in vitro and in vivo data strongly suggest a role for PKC-delta in AngII induced cardiac fibrosis.

Topics: Acetophenones; Angiotensin II; Animals; Benzopyrans; Cell Proliferation; Collagen; Enzyme Inhibitors; Fibroblasts; Fibrosis; Male; Myocardium; Protein Kinase C-delta; Rats; Rats, Sprague-Dawley; RNA, Small Interfering