Oral administration of leucine stimulates ribosomal protein mRNA translation but not global rates of protein synthesis in the liver of rats

T. G. Anthony, J. C. Anthony, F. Yoshizawa, Scot Kimball, Leonard "Jim" Jefferson

Research output: Contribution to journalArticle

90 Citations (Scopus)

Abstract

The objective of the current study was to examine the role of the branched-chain amino acid (BCAA) leucine in the regulation of hepatic protein synthesis and ribosomal protein (rp) mRNA translation in vivo Food-deprived (18 h) male rats (200 g) were orally administered saline (control) or 270 mg leucine, isoleucine or valine and killed 1 h later. Administration of any BCAA resulted in enhanced phosphorylation of eukaryotic initiation factor (elF) 4E-binding protein-1 (4E-BP1) compared with controls. However, leucine was the most effective at stimulating phosphorylation of 4E-BP1 as well as the 70-kDa ribosomal protein S6 kinase (S6K1). Despite these effects on components of the translation initiation process, there were no differences in total protein synthesis rates among treatment groups. The distribution of rp (S4, S8, L26) and non-rp (albumin,β-actin) mRNAs across sucrose density gradients showed that the preponderance of hepatic rp mRNAs in control rats was unloaded from polysomes. Of the BCAA, only leucine was the most effective in causing a shift in the distribution of rp mRNA to polysomes compared with controls. Non-rp transcripts remained mainly polysome-associated under all conditions. These results suggest that leucine is most effective among the BCAA in its ability to stimulate translation of rp mRNA in liver. Furthermore, the translation of rp mRNA is disjointed from rates of total protein synthesis in liver and related to the degree of S6K1 phosphorylation.

Original languageEnglish (US)
Pages (from-to)1171-1176
Number of pages6
JournalJournal of Nutrition
Volume131
Issue number4
StatePublished - Apr 18 2001

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Ribosomal Proteins
Protein Biosynthesis
Branched Chain Amino Acids
Leucine
Oral Administration
Polyribosomes
Messenger RNA
Liver
Phosphorylation
Proteins
Carrier Proteins
Eukaryotic Initiation Factor-4E
70-kDa Ribosomal Protein S6 Kinases
Isoleucine
Valine
Sucrose
Actins
Albumins
Food

All Science Journal Classification (ASJC) codes

  • Medicine (miscellaneous)
  • Nutrition and Dietetics

Cite this

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title = "Oral administration of leucine stimulates ribosomal protein mRNA translation but not global rates of protein synthesis in the liver of rats",
abstract = "The objective of the current study was to examine the role of the branched-chain amino acid (BCAA) leucine in the regulation of hepatic protein synthesis and ribosomal protein (rp) mRNA translation in vivo Food-deprived (18 h) male rats (200 g) were orally administered saline (control) or 270 mg leucine, isoleucine or valine and killed 1 h later. Administration of any BCAA resulted in enhanced phosphorylation of eukaryotic initiation factor (elF) 4E-binding protein-1 (4E-BP1) compared with controls. However, leucine was the most effective at stimulating phosphorylation of 4E-BP1 as well as the 70-kDa ribosomal protein S6 kinase (S6K1). Despite these effects on components of the translation initiation process, there were no differences in total protein synthesis rates among treatment groups. The distribution of rp (S4, S8, L26) and non-rp (albumin,β-actin) mRNAs across sucrose density gradients showed that the preponderance of hepatic rp mRNAs in control rats was unloaded from polysomes. Of the BCAA, only leucine was the most effective in causing a shift in the distribution of rp mRNA to polysomes compared with controls. Non-rp transcripts remained mainly polysome-associated under all conditions. These results suggest that leucine is most effective among the BCAA in its ability to stimulate translation of rp mRNA in liver. Furthermore, the translation of rp mRNA is disjointed from rates of total protein synthesis in liver and related to the degree of S6K1 phosphorylation.",
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Oral administration of leucine stimulates ribosomal protein mRNA translation but not global rates of protein synthesis in the liver of rats. / Anthony, T. G.; Anthony, J. C.; Yoshizawa, F.; Kimball, Scot; Jefferson, Leonard "Jim".

In: Journal of Nutrition, Vol. 131, No. 4, 18.04.2001, p. 1171-1176.

Research output: Contribution to journalArticle

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T1 - Oral administration of leucine stimulates ribosomal protein mRNA translation but not global rates of protein synthesis in the liver of rats

AU - Anthony, T. G.

AU - Anthony, J. C.

AU - Yoshizawa, F.

AU - Kimball, Scot

AU - Jefferson, Leonard "Jim"

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