Branched-chain amino acids, hepatocyte growth factor and protein production in the liver

Although the functions associated with differentiation are thought to be suppressed when cells proliferate, recent studies have shown that several mitogens can stimulate functions such as protein production under certain physiological conditions. Hepatocyte growth factor (HGF) is now considered to be a pluripotent factor and has been shown to stimulate the differentiated functions of hepatocytes, as well as their proliferation. The use of HGF for the treatment of liver disease, especially hepatic failure, has been suggested. Because patients with decompensated liver cirrhosis have decreased plasma concentrations of branched-chain amino acids (BCAAs), many investigations in laboratory animals and patients have been designed to demonstrate the benefits of supplementation of BCAAs on the hepatic metabolism of proteins. However, the mechanisms involved in the specific actions of BCAAs remain to be elucidated. Amino acids are molecules that modulate numerous cellular functions. BCAAs are known to influence gene expression, cellular metabolism, amino acid transport, and protein turnover. In this paper, we show the potential of BCAAs for stimulating HGF synthesis in the liver and discuss the possibility that BCAAs stimulate protein production by hepatocytes through the induction of HGF.