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Regulation of cardiac fibroblast population and cell fate by Scleraxis (15.2)
Author(s) -
Bagchi Rushita,
Roche Patricia,
Aroutiounova Nina,
Schweitzer Ronen,
Czubryt Michael
Publication year - 2014
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.28.1_supplement.15.2
Subject(s) - myofibroblast , fibroblast , population , microbiology and biotechnology , fibronectin , periostin , downregulation and upregulation , extracellular matrix , biology , vimentin , chemistry , fibrosis , pathology , cell culture , immunology , genetics , gene , medicine , immunohistochemistry , environmental health
Fibroblasts are cells of mesenchymal origin that constitute majority of the cardiac non‐myocyte population. They play a contributory role in development and structure of the myocardium, cellular signaling and electromechanical function of the heart‐ both in healthy and diseased conditions. Scleraxis (Scx) has been demonstrated to play a vital role in human collagen gene regulation and synthesis of extracellular matrix (ECM) components. Genetic ablation of Scx caused marked changes in the matrix composition of hearts of Scx null (KO) mice. Based on these observations, we hypothesized that the overall changes occurring in the myocardium may be due to a net change in population of the contributory synthetic fibroblasts. Using single‐cell suspensions from Scx KO and wildtype (WT) hearts, flow cytometry analysis was performed. There was a significant reduction (>40%) in DDR2 positive fibroblasts in Scx KO hearts compared to WT samples. There was also a trending decrease in the population of cells that stained positive for α‐smooth muscle actin (αSMA), a marker of activated contractile myofibroblast phenotype. Gene and protein expression analyses of fibroblast/ myofibroblast markers (vimentin, periostin, EDA‐fibronectin, SMemb) exhibited an overall downregulation of these proteins in myocardium devoid of Scx‐ thus suggesting involvement of Scx in fibroblast cell fate regulation. We hypothesized that Scx may also be responsible for modulating the process of fibroblast phenoconversion‐ a phenomenon that is known to accompany cardiac remodeling. qPCR and immunoblotting analyses of Scx KO hearts demonstrated a significant downregulation of αSMA expression. shRNA‐mediated knockdown of Scx gene expression in primary cardiac proto‐myofibroblasts resulted in marked diminution of this myofibroblast marker protein, thereby demonstrating a direct role of Scx in fibroblast phenoconversion. These findings identify Scx as a novel regulator of cardiac fibroblast population and cell fate. Grant Funding Source : Supported by the Canadian Institutes of Health Research and St. Boniface Research Foundatio