Impact of type 1 diabetes on cardiac fibroblast activation: enhanced cell cycle progression and reduced myofibroblast content in diabetic myocardium.
Animals; Blood Glucose/metabolism; Blotting; Body Weight/physiology; Cell Cycle Proteins/biosynthesis; Cell Cycle/*physiology; Cell Differentiation/physiology; Cell Proliferation; Cell Separation; Diabetes Mellitus; Echocardiography; Experimental/pathology; Fibroblasts/*physiology; Male; Microarray Analysis; Myocardium/cytology/*pathology; Myofibroblasts/*physiology; Phenotype; Rats; RNA/biosynthesis/isolation & purification; Signal Transduction/physiology; Sprague-Dawley; Type 1/diagnostic imaging/*pathology; Western
Diabetic patients are prone to developing myocardial fibrosis and suffer from decreased wound healing capabilities. The purpose of this study was to determine whether diabetes alters cardiac fibroblast activity in the myocardium in a 6-wk streptozotocin-induced type 1 diabetic model. In vivo echocardiography indicated significant dilation of the left ventricle (LV) in the diabetic animals, while cardiac function was comparable to that in the normal group. We isolated cardiac fibroblasts from diabetic and control hearts and observed increased proliferation of the diabetic fibroblasts. Microarray analysis using mRNA collected from whole LVs revealed downregulation of known inhibitors of proliferation, p53 and p21, in the diabetic group, consistent with our proliferation data. Western blot analysis confirmed a reduction in p53 protein expression in the diabetic hearts compared with control. We explored the potential signaling underlying the downregulation of these cell cycle mediators and determined that activated Akt, a signal that inhibits p53, was elevated in the diabetic group. Surprisingly, the hearts from the diabetic group contained lower levels of the myofibroblast marker alpha-smooth muscle actin (alpha-SMA) and higher levels of desmin and platelet endothelial cell adhesion molecule (PECAM). The isolated fibroblasts from the diabetic group also contained significantly less alpha-SMA. These data suggest that early-stage diabetic hearts contain highly proliferative fibroblasts, which predisposes the diabetic myocardium to fibrosis, but have fewer myofibroblasts, which may compromise wound healing.
Shamhart Patricia E; Luther Daniel J; Hodson Ben R; Koshy John C; Ohanyan Vahagn; Meszaros J Gary
American journal of physiology. Endocrinology and metabolism
2009
2009-11
Article information provided for research and reference use only. All rights are retained by the journal listed under publisher and/or the creator(s).
<a href="http://doi.org/10.1152/ajpendo.00327.2009" target="_blank" rel="noreferrer noopener">10.1152/ajpendo.00327.2009</a>
TRPV4 channels mediate cardiac fibroblast differentiation by integrating mechanical and soluble signals.
*Calcium Signaling; *Cell Differentiation; *Mechanotransduction; Animals; Cellular; Extracellular Matrix/metabolism/physiology; Fibroblasts/*physiology; Gene Knockdown Techniques; Male; Monoterpenes/pharmacology; Myocardium/cytology; Myofibroblasts/metabolism; Rats; RNA; Small Interfering/genetics; Sprague-Dawley; Transforming Growth Factor beta1/physiology; TRPM Cation Channels/antagonists & inhibitors/metabolism; TRPV Cation Channels/genetics/*metabolism
The phenotypic switch underlying the differentiation of cardiac fibroblasts into hypersecretory myofibroblasts is critical for cardiac remodeling following myocardial infarction. Myofibroblasts facilitate wound repair in the myocardium by secreting and organizing extracellular matrix (ECM) during the wound healing process. However, the molecular mechanisms involved in myofibroblast differentiation are not well known. TGF-beta has been shown to promote differentiation and this, combined with the robust mechanical environment in the heart, lead us to hypothesize that the mechanotransduction and TGF-beta signaling pathways play active roles in the differentiation of cardiac fibroblasts to myofibroblasts. Here, we show that the mechanosensitve ion channel TRPV4 is required for TGF-beta1-induced differentiation of cardiac fibroblasts into myofibroblasts. We found that the TRPV4-specific antagonist AB159908 and siRNA knockdown of TRPV4 significantly inhibited TGFbeta1-induced differentiation as measured by incorporation of alpha-SMA into stress fibers. Further, we found that
Adapala Ravi K; Thoppil Roslin J; Luther Daniel J; Paruchuri Sailaja; Meszaros J Gary; Chilian William M; Thodeti Charles K
Journal of molecular and cellular cardiology
2013
2013-01
Article information provided for research and reference use only. All rights are retained by the journal listed under publisher and/or the creator(s).
<a href="http://doi.org/10.1016/j.yjmcc.2012.10.016" target="_blank" rel="noreferrer noopener">10.1016/j.yjmcc.2012.10.016</a>