Induction of calponin-h1 by transforming growth factor- β1 in cultured human Ito cells, LI90

Abstract

We investigated the effect of transforming growth factor- β1 (TGF- β1) on the expression of calponin-h1, α-smooth muscle actin ( α-SMA), and extracellular matrix (ECM) components in a cultured human Ito cell line, LI90. The TGF- β1 treatment stimulated productions of hyaluronic acid and laminin, and significantly decreased the secretion of hepatocyte growth factor in LI90 cells. The functional characteristics of LI90 cells were compatible with those of human-activated Ito cells that are known as pericyte-like mesenchymal liver cells. TGF- β1 induced a slight growth-inhibition of LI90 cells. TGF- β1 enhanced the expressions of both α-SMA and calponin-h1 at the protein level, while tumor necrosis factor- α and interleukin-1 α did not affect the expressions of these cytoskeletal proteins on LI90 cells. The addition of TGF- β1 to LI90 cells resulted in a significant increase of calponin-h1 mRNA levels, but not calponin-h2. These data suggest that the expression of calponin-h1 is controlled at the level of mRNA under the coordinate regulation together with α-SMA as the process of perpetuation of activated Ito cells promoted by TGF- β1. The identification of smooth muscle features promoted by TGF- β1 support the hypothesis that the activation of Ito cells coincides with their contractile behavior, indicating that these cells may be important in vasoregulation during liver injury and fibrosis.