Adaptational modification of serine and threonine metabolism in the liver to essential amino acid deficiency in rats

• Published in: Amino acids Vol. 36; no. 3; pp. 555 - 562
• Main Authors: Nagao, Kenji, Bannai, Makoto, Seki, Shinobu, Mori, Masato, Takahashi, Michio
• Format: Journal Article
• Language: English
• Published: Vienna Vienna : Springer Vienna 01.03.2009; Springer Vienna; Springer Nature B.V
• Subjects: Amino acids; Amino Acids, Essential - administration & dosage; Amino Acids, Essential - deficiency; Analytical Chemistry; Animals; Biochemical Engineering; Biochemistry; Biomedical and Life Sciences; Diet; Diets; Elevated; Elevation; Food, Formulated; Gene Expression; L-Serine Dehydratase - biosynthesis; Life Sciences; Liver; Liver - enzymology; Liver - metabolism; Lysine; Metabolism; Neurobiology; Original Article; Phosphoglycerate Dehydrogenase - biosynthesis; Proteomics; Rats; Rats, Wistar; RNA, Messenger - metabolism; Rodents; Serine - blood; Serine - metabolism; Threonine - blood; Threonine - metabolism; Amino acid deficiency; PHGDH; SDS; Threonine; Serine
• ISSN: 0939-4451; 1438-2199
• DOI: 10.1007/s00726-008-0117-7

It is known that plasma serine and threonine concentrations are elevated in rats chronically fed an essential amino acid deficient diet, but the underlying mechanisms including related gene expressions or serine and threonine concentrations in liver remained to be elucidated. We fed rats lysine or valine deficient diet for 4 weeks and examined the mRNA expressions of serine synthesising (3-phosphoglycerate dehydrogenase, PHGDH) and serine/threonine degrading enzymes (serine dehydratase, SDS) in the liver. Dietary deficiency induced marked elevation of hepatic serine and threonine levels associated with enhancement of PHGDH mRNA expression and repression of SDS mRNA expression. Increases in plasma serine and threonine levels due to essential amino acid deficiency in diet were caused by marked increases in hepatic serine and threonine levels. Proteolytic responses to the amino acid deficiency may be lessened by storing amino radicals as serine and inducing anorexia through elevation of threonine.