Gene interactions and pathways from curated databases and text-mining
Biochem Biophys Res Commun 2009, PMID: 19799871

Effects of PI3K catalytic subunit and Akt isoform deficiency on mTOR and p70S6K activation in myoblasts.

Matheny, Ronald W; Adamo, Martin L

The PI3K/Akt/mTOR signaling pathway is critical for cellular growth and survival in skeletal muscle, and is activated in response to growth factors such as insulin-like growth factor-I (IGF-I). We found that in C2C12 myoblasts, deficiency of PI3K p110 catalytic subunits or Akt isoforms had distinct effects on phosphorylation of mTOR and p70S6K. siRNA-mediated knockdown of PI3K p110alpha, p110beta, and simultaneous knockdown of p110alpha and p110beta resulted in increased basal and IGF-I-stimulated phosphorylation of mTOR S2448 and p70S6K T389; however, phosphorylation of S6 was reduced in p110beta-deficient cells, possibly due to reductions in total S6 protein. We found that IGF-I-stimulated Akt1 activity was enhanced in Akt2- or Akt3-deficient cells, and that knockdown of individual Akt isoforms increased mTOR/p70S6K activation in an isoform-specific fashion. Conversely, levels of IGF-I-stimulated p70S6K phosphorylation in cells simultaneously deficient in both Akt1 and Akt3 were increased beyond those seen with loss of any single Akt isoform, suggesting an alternate, Akt-independent mechanism that activates mTOR/p70S6K. Our results collectively suggest that mTOR/p70S6K is activated in a PI3K/Akt-dependent manner, but that in the absence of p110alpha or Akt, alternate pathway(s) may mediate activation of mTOR/p70S6K in C2C12 myoblasts.

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Text Mining Data

Akt1 → IGF-I: " We found that IGF-I stimulated Akt1 activity was enhanced in Akt2- or Akt3-deficient cells, and that knockdown of individual Akt isoforms increased mTOR/p70S6K activation in an isoform-specific fashion "

p70S6K → IGF-I: " Conversely, levels of IGF-I stimulated p70S6K phosphorylation in cells simultaneously deficient in both Akt1 and Akt3 were increased beyond those seen with loss of any single Akt isoform, suggesting an alternate, Akt independent mechanism that activates mTOR/p70S6K "

mTOR/p70S6K — PI3K/Akt: " Our results collectively suggest that mTOR/p70S6K is activated in a PI3K/Akt dependent manner, but that in the absence of p110alpha or Akt, alternate pathway ( s ) may mediate activation of mTOR/p70S6K in C2C12 myoblasts "

mTOR/p70S6K — PI3K/Akt: " Our results collectively suggest that mTOR/p70S6K is activated in a PI3K/Akt dependent manner, but that in the absence of p110alpha or Akt, alternate pathway ( s ) may mediate activation of mTOR/p70S6K in C2C12 myoblasts "

mTOR/p70S6K — PI3K/Akt: " Our results collectively suggest that mTOR/p70S6K is activated in a PI3K/Akt dependent manner, but that in the absence of p110alpha or Akt, alternate pathway ( s ) may mediate activation of mTOR/p70S6K in C2C12 myoblasts "

mTOR/p70S6K — PI3K/Akt: " Our results collectively suggest that mTOR/p70S6K is activated in a PI3K/Akt dependent manner, but that in the absence of p110alpha or Akt, alternate pathway ( s ) may mediate activation of mTOR/p70S6K in C2C12 myoblasts "

Manually curated Databases

No curated data.