IndraLab
Statements
rlimsp
"This led to phosphorylation of IRS-1 by S6K1 at multiple serine residues including Ser-270, Ser-307, Ser-636, and Ser-1101 in human IRS-1 (Ser-265, Ser-302, Ser-632, and Ser-1097, in rodent IRS-1). Direct phosphorylation of these sites by S6K1 was observed in an in vitro kinase assay using purified IRS-1 and S6K1."
rlimsp
"We report that, by several criteria, S6K1 does not phosphorylate IRS1 at serine 307 in response to insulin in intact human primary adipocytes: (i) The time-courses for phosphorylation of S6K1 and its phosphorylation of S6 are not compatible with the phosphorylation of IRS1 at serine 307; (ii) A dominant-negative construct of S6K1 inhibits the phosphorylation of S6, without effect on the phosphorylation of IRS1 at serine 307; (iii) The specific inhibitor of S6K1 PF-4708671 inhibits the phosphorylation of S6, without effect on phosphorylation of IRS1 at serine 307."
"Nevertheless, s6k1-deficient mice remain sensitive to insulin owing to the apparent loss of a negative feedback loop from s6k1 to insulin receptor substrate 1 (irs1), which blunts s307 and s636/s639 phosphorylation; thus under conditions of nutrient satiation s6k1 negatively regulatesinsulin."
reach
"In addition, when mTORC1 is activated, S6K1 could directly phosphorylate Insulin receptor substrate 1 (IRS1; S307 and S636 and S639) and promote its degradation, which subsequently blunts phosphoinositide 3-kinase (PI3K)-AKT activation and its downstream effects such as glucose uptake and glycogen accumulation."
reach
"These include mammalian target of rapamycin (mTOR)-mediated phosphorylation of IRS1 serine 636 (Ser636) and serine 639 (Ser639), ribosomal S6 kinase 1 (S6K1)-mediated phosphorylation of IRS1 serine 307 [Ser307 (mouse serine 302) (Ser302)] and serine 1101, IkappaB kinase beta (IKKbeta) - and c-Jun N-terminal kinase (JNK)-mediated phosphorylation of IRS1 serine 312 [Ser312 (mouse Ser307)], and protein kinase zeta mediated phosphorylation of IRS1 serine 323 (mouse serine 318)."
sparser
"We report that, by several criteria, S6K1 does not phosphorylate IRS1 at serine 307 in response to insulin in intact human primary adipocytes: (i) The time-courses for phosphorylation of S6K1 and its phosphorylation of S6 are not compatible with the phosphorylation of IRS1 at serine 307; (ii) A dominant-negative construct of S6K1 inhibits the phosphorylation of S6, without effect on the phosphorylation of IRS1 at serine 307; (iii) The specific inhibitor of S6K1 PF-4708671 inhibits the phosphorylation of S6, without effect on phosphorylation of IRS1 at serine 307."