The α1β1 integrin is expressed during neointima formation in rat arteries and mediates collagen matrix reorganization

Abstract

Remodeling of the extracellular matrix by activated mesenchymal cells (myofibroblasts) is a critical aspect of wound repair in all adult organs. Collagen-dependent gel contraction, a process requiring integrin function, is an established in vitro assay thought to mimic in vivo matrix remodeling. Numerous data have implicated the α2β1 integrin in various cell types as the primary collagen receptor responsible for collagen gel contraction. However, evidence from the literature suggests that the major collagen binding integrin expressed on mesenchymally derived cells in situ is the α1β1 integrin, not the α2β1 integrin. In this report, we use a rat vascular injury model to illustrate that the α1β1 integrin is the major collagen receptor expressed on vascular smooth muscle cells after injury. Using two smooth muscle cell lines, expressing either the α1β1 integrin alone or both the α1β1 and α2β1 integrins, along with Chinese hamster ovary cells transfected with the α1 integrin, we demonstrate that α1β1 supports not only collagen-dependent adhesion and migration, but also gel contraction. These data suggest that in vivo the α1β1 integrin is a critical collagen receptor on mesenchymally derived cells potentially involved in matrix remodeling after injury.