Cultured hepatic stellate cells (HSCs) are known to change their morphology and function with respect to the production of extracellular matrices (ECMs) and matrix metalloproteinases (MMPs) in response to ECM components. We examined the regulatory role of the native form of type I collagen fibrils in pro-MMP-2 production and activation in cultured HSCs. Gelatin zymography of the conditioned media revealed that pro- and active form of MMP-2 was increased in the HSCs cultured on type I collagen gel but not on type I collagen-coated surface, gelatin-coated surface, type IV collagen-coated surface, or Matrigel, suggesting the importance of the native form of type I collagen fibrils in pro-MMP-2 production and activation. The induction of active MMP-2 by extracellular type I collagen was suppressed by the blocking antibody against integrin β1 subunits, indicating the involvement of integrin signaling in pro-MMP-2 activation. RT-PCR analysis indicated that MMP-2, membrane type-1 MMP (MT1-MMP) and tissue inhibitor of metalloproteinase-2 (TIMP-2) mRNA levels were elevated in HSCs cultured on type I collagen gel. The increased MT1-MMP proteins were localized on the cell surface of HSCs cultured on type I collagen gel. In contrast to the expression of MMP-2, HSCs showed a great decline in MMP-13 expression in HSCs cultured on type I collagen gel. These results indicate that the native fibrillar (polymerized) but not monomeric form of type I collagen induced pro-MMP-2 production and activation through MT1-MMP and TIMP-2 in cultured HSCs, suggesting an important role of HSCs in ECM remodeling in the hepatic perisinusoidal spaces.
2003 by Japan Society for Cell Biology