Cathepsin G increases MMP expression in normal human fibroblasts through fibronectin fragmentation, and induces the conversion of proMMP-1 to active MMP-1

Abstract

Fibronectin (Fn) is a glycoprotein that is found in the plasma and is a component of the extracellular matrix (ECM). It binds to collagen and fibulin, as well as a class of the cell surface adhesion receptors termed integrins, and has been shown to be involved in various biological activities, including cell attachment, cell migration, and wound healing [1]. Fn is readily degraded into fibronectin fragment (Fn-frs) through the action of many different types of proteases [2] containing cathepsin G [3]. The expression of MMP (matrix metalloproteinase) by Fn-frs (Fn-f29; N-terminal heparin binding fragment, 45 kDa; Fn-f45, collagen binding fragment, and 110 kDa; Fn-f110 cell binding fragment) has been studied in chondrocytes [4–6], however, little is known about the roles of Fn-frs, or cathepsin G-mediated fragmentation of Fn, in aged human skin and normal human fibroblasts (NHFs).