Linked Life Data

16221682

Source:http://linkedlifedata.com/resource/pubmed/id/16221682

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
49
pubmed:dateCreated
2005-12-5
pubmed:abstractText
The insulin-signaling pathway leading to the activation of Akt/protein kinase B has been well characterized except for a single step, the phosphorylation of Akt at Ser-473. Double-stranded DNA-dependent protein kinase (DNA-PK), ataxia telangiectasia mutated (ATM) gene product, integrin-linked kinase (ILK), protein kinase Calpha (PKCalpha), and mammalian target of rapamycin (mTOR), when complexed to rapamycin-insensitive companion of mTOR (RICTOR), have all been identified as playing a critical role in Akt Ser-473 phosphorylation. However, the apparently disparate results reported in these studies are difficult to evaluate, given that different stimuli and cell types were examined and that all of the candidate proteins have never been systematically studied in a single system. Additionally, none of these studies were performed in a classical insulin-responsive cell type or tissue such as muscle or fat. We therefore examined each of these candidates in 3T3-L1 adipocytes. In vitro kinase assays, using different subcellular fractions of 3T3-L1 adipocytes, revealed that phosphatidylinositol 3,4,5-trisphosphate-stimulated Ser-473 phosphorylation correlated well with the amount of DNA-PK, mTOR, and RICTOR but did not correlate with levels of ATM, ILK, and PKCalpha. PKCalpha was completely absent from compartments with Ser-473 phosphorylation activity. Although purified DNA-PK could phosphorylate a peptide derived from Akt that contains amino acid Ser-473, it could not phosphorylate full-length Akt2. Vesicles immunoprecipitated from low density microsomes using antibodies directed against mTOR or RICTOR had phosphatidylinositol 3,4,5-trisphosphate-stimulated Ser-473 activity that was sensitive to wortmannin but not staurosporine. In contrast, immunopurified low density microsome vesicles containing ILK could not phosphorylate Akt on Ser-473 in vitro. Small interference RNA knockdown of RICTOR, but not DNA-PK, ATM, or ILK, suppressed insulin-activated Ser-473 phosphorylation and, to a lesser extent, Thr-308 phosphorylation in 3T3-L1 adipocytes. Based on our cell-free kinase and small interference RNA results, we conclude that mTOR complexed to RICTOR is the Ser-473 kinase in 3T3-L1 adipocytes.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
http://linkedlifedata.com/resource/pubmed/chemical/Carrier Proteins, http://linkedlifedata.com/resource/pubmed/chemical/DNA-Activated Protein Kinase, http://linkedlifedata.com/resource/pubmed/chemical/Insulin, http://linkedlifedata.com/resource/pubmed/chemical/MTOR protein, human, http://linkedlifedata.com/resource/pubmed/chemical/Phosphatidylinositol Phosphates, http://linkedlifedata.com/resource/pubmed/chemical/Protein Kinases, http://linkedlifedata.com/resource/pubmed/chemical/Proto-Oncogene Proteins c-akt, http://linkedlifedata.com/resource/pubmed/chemical/RICTOR protein, human, http://linkedlifedata.com/resource/pubmed/chemical/RNA, Small Interfering, http://linkedlifedata.com/resource/pubmed/chemical/Serine, http://linkedlifedata.com/resource/pubmed/chemical/TOR Serine-Threonine Kinases, http://linkedlifedata.com/resource/pubmed/chemical/mTOR protein, mouse, http://linkedlifedata.com/resource/pubmed/chemical/phosphatidylinositol...
pubmed:status
MEDLINE
pubmed:month
Dec
pubmed:issn
0021-9258
pubmed:author
pubmed:issnType
Print
pubmed:day
9
pubmed:volume
280
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
40406-16
pubmed:dateRevised
2011-11-17
pubmed:meshHeading
pubmed:year
2005
pubmed:articleTitle
mTOR.RICTOR is the Ser473 kinase for Akt/protein kinase B in 3T3-L1 adipocytes.
pubmed:affiliation
Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, Missouri 63110, USA.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't, Research Support, N.I.H., Extramural