Involvement and possible role of transglutaminases 1 and 2 in mediating fibrotic signalling, collagen cross-linking and cell proliferation in neonatal rat ventricular fibroblasts

• Published in: PloS one Vol. 18; no. 2; p. e0281320
• Main Authors: Al-U’datt, Doa’a G. F., Tranchant, Carole C., Al-Husein, Belal, Hiram, Roddy, Al-Dwairi, Ahmed, AlQudah, Mohammad, Al-shboul, Othman, Jaradat, Saied, Alqbelat, Jenan, Almajwal, Ali
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 27.02.2023; Public Library of Science (PLoS)
• Subjects: Actin; Analysis; Animals; Animals, Newborn; Apoptosis; Bcl-2 protein; Bcl-x protein; Biology and Life Sciences; Cardiology; Cardiomyocytes; Cardiomyopathy; Cardiovascular diseases; Cell growth; Cell Proliferation; Chromatography, Liquid; Collagen; Complications and side effects; Connective tissue growth factor; Connective tissues; Cross-linking; Crosslinked polymers; Crosslinking; Cyclin D1; Enzyme-linked immunosorbent assay; Enzymes; Extracellular matrix; Extracellular Matrix Proteins; Fibroblasts; Fibronectin; Fibrosis; Gene expression; Growth factors; Health aspects; Heart diseases; Heart failure; Homeostasis; Isoforms; Lymphocytes B; Lymphoma; Matrix metalloproteinase; Matrix Metalloproteinase 2 - genetics; Matrix metalloproteinases; Medical research; Medicine and Health Sciences; Medicine, Experimental; Metalloproteinase; Muscles; Neonates; Newborn babies; Physical Sciences; Prevention; Proteins; Rats; Risk factors; RNA; Scientific equipment and supplies industry; Signaling; siRNA; Smooth muscle; Tandem Mass Spectrometry; Transglutaminases; Ventricle; Saudi Arabia; United States; United States > US; Japan
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0281320

Transglutaminase (TG) isoforms control diverse normal and pathophysiologic processes through their capacity to cross-link extracellular matrix (ECM) proteins. Their functional and signalling roles in cardiac fibrosis remain poorly understood, despite some evidence of TG2 involvement in abnormal ECM remodelling in heart diseases. In this study, we investigated the role of TG1 and TG2 in mediating fibrotic signalling, collagen cross-linking, and cell proliferation in healthy fibroblasts by siRNA-mediated knockdown. siRNA for TG1, TG2 or negative control was transfected into cultured neonatal rat ventricular fibroblasts and cardiomyocytes. mRNA expression of TGs and profibrotic, proliferation and apoptotic markers was assessed by qPCR. Cell proliferation and soluble and insoluble collagen were determined by ELISA and LC-MS/MS, respectively. TG1 and TG2 were both expressed in neonatal rat cardiomyocytes and fibroblasts before transfection. Other TGs were not detected before and after transfection. TG2 was predominantly expressed and more effectively silenced than TG1. Knocking down TG1 or TG2 significantly modified profibrotic markers mRNA expression in fibroblasts, decreasing connective tissue growth factor (CTGF) and increasing transforming growth factor-β1 compared to the negative siRNA control. Reduced expression of collagen 3A1 was found upon TG1 knockdown, while TG2 knockdown raised α-smooth muscle actin expression. TG2 knockdown further increased fibroblast proliferation and the expression of proliferation marker cyclin D1. Lower insoluble collagen content and collagen cross-linking were evidenced upon silencing TG1 or TG2. Transcript levels of collagen 1A1, fibronectin 1, matrix metalloproteinase-2, cyclin E2, and BCL-2-associated X protein/B-cell lymphoma 2 ratio were strongly correlated with TG1 mRNA expression, whereas TG2 expression correlated strongly with CTGF mRNA abundance. These findings support a functional and signalling role for TG1 and TG2 from fibroblasts in regulating key processes underlying myocardial ECM homeostasis and dysregulation, suggesting that these isoforms could be potential and promising targets for the development of cardiac fibrosis therapies.