Elevation of the Hepatic Level of Albumin mRNA in Rats Fed a Non-protein Diet Supplemented with Sulfur-containing Amino Acids and Threonine

Abstract

A nitrogen-sparing action of sulfur-containing amino acids and threonine in rats fed a non-protein diet has been reported from our laboratory. The nutritional significance of dietary sulfur-containing amino acids and threonine on the expression of the albumin gene was investigated. An elevated level of serum albumin and its mRNA in liver was observed in rats fed a non-protein diet supplemented with sulfur-containing amino acids and threonine, but the level of albumin mRNA of the group supplemented with cystine and threonine was much higher than that of the methionine and threonine supplemented group. Nuclear run-on assay showed an enhanced rate of albumin gene transcription in liver nuclei of rats fed the cystine and threonine supplemented diet. We showed the evidence that cystine is a more efficient amino acid than methionine to maintain the expression of the albumin gene at a high level in rats fed a non-protein diet.