Transforming growth factor‐β1 induces collagen synthesis and accumulation via p38 mitogen‐activated protein kinase (MAPK) pathway in cultured L6E9 myoblasts

Abstract
Transforming growth factor-β (TGF-β) plays a pivotal role in the extracellular matrix accumulation observed in chronic progressive tissue fibrosis, but the intracellular signaling mechanism by which TGF-β stimulates this process remains poorly understood. We examined whether mitogen-activated protein kinase (MAPK) routes were involved in TGF-β1-induced collagen expression in L6E9 myoblasts. TGF-β1 induced p38 and extracellular signal-regulated kinase (ERK) 1/2 phosphorylation whereas no effect on Jun N-terminal kinase phosphorylation was observed. Biochemical blockade of p38 but not of the ERK MAPK pathway abolished TGF-β1-induced α2(I) collagen mRNA expression and accumulation. These data indicate that TGF-β1-induced p38 activation is involved in TGF-β1-stimulated collagen synthesis