Lysyl oxidase expression in cardiac fibroblasts is regulated by α2β1 integrin interactions with the cellular microenvironment

Abstract

Lysyl oxidase (LOX) catalyzes crosslink formation between fibrillar collagens and elastins and an increase in LOX activity has been associated with cardiac fibrosis following myocardial infarction (MI). It has been previously reported that LOX expression is regulated by growth factors and cytokines including transforming growth factor (TGF-β1); however, it is unclear how the biophysical and biochemical properties of the cellular microenvironment affect LOX expression. In this study, we isolated rat cardiac fibroblasts (CF) and infarct cardiac fibroblasts (ICF), from healthy and 1-week post-MI left ventricular tissue respectively, and cultured them under varied substrate conditions in vitro to assess their influence on LOX expression. Culture of ICF on collagen I-coated plates increased LOX expression versus uncoated plates with an additional increase observed with the presence of TGF-β1. To further investigate the effect of integrin interactions with collagen I on LOX expression, we inhibited the α2β1 integrin from binding to collagen I and found gene and protein expression of LOX to be downregulated. Together, this demonstrates that the interaction of α2β1 integrin to collagen I in the cellular microenvironment can regulate expression of LOX. Further studies investigating additional integrin interactions may identify therapeutic targets for treating cardiac fibrosis.