Premium
Effect of supplemental dietary zinc on the mTOR signaling pathway in skeletal muscle from post‐absorptive mice
Author(s) -
McClung James P.,
Tarr Tyson N.,
MoralesMartinez Nelson,
Scrimgeour Angus G.,
Young Andrew J.
Publication year - 2006
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.20.4.a627-b
Subject(s) - ribosomal protein s6 , pi3k/akt/mtor pathway , phosphorylation , protein kinase b , p70 s6 kinase 1 , skeletal muscle , medicine , chemistry , endocrinology , ribosomal s6 kinase , threonine , serine , rptor , biology , signal transduction , biochemistry
The mammalian target of rapamycin (mTOR) is a serine/threonine kinase involved in the molecular regulation of protein synthesis. Supplemental zinc (Zn) stimulates mTOR activity in cell culture models, but this effect has not been confirmed in vivo . Therefore, the effect of dietary Zn on the mTOR‐signaling pathway in skeletal muscle was examined in adult male mice (C57BL/6J) fed Zn‐marginal (ZM, 5 ppm) diets for 4 wks. Animals were fasted for 12 h (F) and/or refed with ZM or Zn‐supplemental (ZS, 300 ppm) diets for 3 or 6 h. Plasma and medial gastrocnemius muscle were collected immediately following euthanization. Protein phosphorylation was detected in muscle using Western‐blotting. Plasma insulin was greater (P < 0.05) in all refed mice as compared to the F mice. Upstream of mTOR, phosphorylation of Akt at Ser 473 and at the PDK‐1 site (Thr 308) was greater (P < 0.05) in ZS mice refed for 3 and 6 h compared to F mice. Downstream of mTOR, phosphorylation of the ribosomal S6 protein at Thr 235/236 was greater (P < 0.05) in ZS mice refed for 3 h compared to F mice. Phosphorylation of the cap‐binding protein eIF4E at Ser 209 was reduced (P < 0.05) in ZM mice refed for 3 h and in ZS mice refed for 6 h compared to the F mice. In conclusion, dietary Zn may influence the molecular regulation of skeletal muscle protein synthesis by affecting the phosphorylation states of proteins in the mTOR pathway, including Akt, ribosomal S6, and eIF4E. Research funded by MRMC.