Inhibition of Hepatic Stellate Cell Collagen Synthesis by N-(Methy1amino)Isobutyric Acid

Authors

Thomas L. Freeman, University of Nebraska Medical Center; Omaha, NE
Kusum K. Kharbanda, University of Nebraska Medical CenterFollow
Dean Tuma, University of Nebraska Medical Center; Omaha, NE
Mark Milliard, University of Nebraska Medical Center; Omaha, NE

Date of this Version

2002

Comments

Published in Biochemical Pharmacology 63 (2002) 697-706.

Abstract

The increased deposition of extracellular matrix by hepatic stellate cells following liver injury, in a process known as activation, is considered a key mechanism for increased collagen content of liver during the development of liver fibrosis. We report that N- (methylamino)isobutyric acid (MeAIB), a specific inhibitor of System A-mediated amino acid uptake, reduces the accumulation of collagen in CFSC-2G hepatic stellate cell cultures and in a rat model of liver injury and fibrosis. Rat CFSC-2G cells were cultured in 0-5 mM MeAIB, and the accumulation and synthesis of collagen were measured by binding to Sirius red F3B and pulse-labeling with [³H]I-proline, respectively. The effect of MeAIB on collagen accumulation in vivo was evaluated utilizing a rat model of hepatic fibrosis. MeAIB inhibited collagen accumulation in CFSC-2G cultures in a concentration-dependent manner with 5 mM MeAIB reducing collagen 44.6 ± 1.2% compared with the control. In CFSC-2G cultures, MeAIB selectively inhibited the incorporation of proline into cellular macromolecules by 43 ± 4%, while the synthesis of proteins containing leucine was not affected. In vivo, oral administration of 160 mg MeAIB/kg body weight per day to rats significantly reduced the hepatic collagen accumulation in response to 1 week of CCI₄-induced liver injury. MeAIB reduces the accumulation of collagen in CFSC-2G hepatic stellate cell cultures and in a CC1₄-induced rat model of liver injury and fibrosis.