PMID- 19955088 OWN - NLM STAT- MEDLINE DCOM- 20100422 LR - 20211203 IS - 1535-9484 (Electronic) IS - 1535-9476 (Print) IS - 1535-9476 (Linking) VI - 9 IP - 2 DP - 2010 Feb TI - Quantitative nuclear proteomics identifies mTOR regulation of DNA damage response. PG - 403-14 LID - 10.1074/mcp.M900326-MCP200 [doi] AB - Cellular nutritional and energy status regulates a wide range of nuclear processes important for cell growth, survival, and metabolic homeostasis. Mammalian target of rapamycin (mTOR) plays a key role in the cellular responses to nutrients. However, the nuclear processes governed by mTOR have not been clearly defined. Using isobaric peptide tagging coupled with linear ion trap mass spectrometry, we performed quantitative proteomics analysis to identify nuclear processes in human cells under control of mTOR. Within 3 h of inhibiting mTOR with rapamycin in HeLa cells, we observed down-regulation of nuclear abundance of many proteins involved in translation and RNA modification. Unexpectedly, mTOR inhibition also down-regulated several proteins functioning in chromosomal integrity and up-regulated those involved in DNA damage responses (DDRs) such as 53BP1. Consistent with these proteomic changes and DDR activation, mTOR inhibition enhanced interaction between 53BP1 and p53 and increased phosphorylation of ataxia telangiectasia mutated (ATM) kinase substrates. ATM substrate phosphorylation was also induced by inhibiting protein synthesis and suppressed by inhibiting proteasomal activity, suggesting that mTOR inhibition reduces steady-state (abundance) levels of proteins that function in cellular pathways of DDR activation. Finally, rapamycin-induced changes led to increased survival after radiation exposure in HeLa cells. These findings reveal a novel functional link between mTOR and DDR pathways in the nucleus potentially operating as a survival mechanism against unfavorable growth conditions. FAU - Bandhakavi, Sricharan AU - Bandhakavi S AD - Department of Biochemistry, University of Minnesota, Minneapolis, Minnesota 55455, USA. FAU - Kim, Young-Mi AU - Kim YM FAU - Ro, Seung-Hyun AU - Ro SH FAU - Xie, Hongwei AU - Xie H FAU - Onsongo, Getiria AU - Onsongo G FAU - Jun, Chang-Bong AU - Jun CB FAU - Kim, Do-Hyung AU - Kim DH FAU - Griffin, Timothy J AU - Griffin TJ LA - eng GR - P30 DK050456/DK/NIDDK NIH HHS/United States GR - R56 DK072004/DK/NIDDK NIH HHS/United States GR - R01 DK072004/DK/NIDDK NIH HHS/United States GR - P30 DK50456/DK/NIDDK NIH HHS/United States GR - DK072004/DK/NIDDK NIH HHS/United States PT - Journal Article PT - Research Support, N.I.H., Extramural PT - Research Support, Non-U.S. Gov't PT - Research Support, U.S. Gov't, Non-P.H.S. DEP - 20091123 PL - United States TA - Mol Cell Proteomics JT - Molecular & cellular proteomics : MCP JID - 101125647 RN - 0 (Intracellular Signaling Peptides and Proteins) RN - 0 (Proteasome Inhibitors) RN - 0 (Proteome) RN - 98600C0908 (Cycloheximide) RN - EC 2.7.1.1 (MTOR protein, human) RN - EC 2.7.11.1 (Protein Serine-Threonine Kinases) RN - EC 2.7.11.1 (TOR Serine-Threonine Kinases) RN - EC 3.4.25.1 (Proteasome Endopeptidase Complex) RN - W36ZG6FT64 (Sirolimus) SB - IM MH - Cell Nucleus/drug effects/*metabolism/radiation effects MH - Cycloheximide/pharmacology MH - *DNA Damage MH - HeLa Cells MH - Humans MH - Intracellular Signaling Peptides and Proteins/antagonists & inhibitors/*metabolism MH - Isotope Labeling MH - Proteasome Endopeptidase Complex/metabolism MH - Proteasome Inhibitors MH - Protein Biosynthesis/drug effects/radiation effects MH - Protein Serine-Threonine Kinases/antagonists & inhibitors/*metabolism MH - Proteome/metabolism MH - Proteomics/*methods MH - Radiation Tolerance/drug effects/radiation effects MH - Radiation, Ionizing MH - Reproducibility of Results MH - Signal Transduction/drug effects/radiation effects MH - Sirolimus/pharmacology MH - TOR Serine-Threonine Kinases PMC - PMC2830849 EDAT- 2009/12/04 06:00 MHDA- 2010/04/23 06:00 PMCR- 2011/02/01 CRDT- 2009/12/04 06:00 PHST- 2009/12/04 06:00 [entrez] PHST- 2009/12/04 06:00 [pubmed] PHST- 2010/04/23 06:00 [medline] PHST- 2011/02/01 00:00 [pmc-release] AID - S1535-9476(20)33808-1 [pii] AID - M900326-MCP200 [pii] AID - 10.1074/mcp.M900326-MCP200 [doi] PST - ppublish SO - Mol Cell Proteomics. 2010 Feb;9(2):403-14. doi: 10.1074/mcp.M900326-MCP200. Epub 2009 Nov 23.