Quantitative nuclear proteomics identifies mTOR regulation of DNA damage response

Sricharan Bandhakavi, Young Mi Kim, Seung Hyun Ro, Hongwei Xie, Getiria Onsongo, Chang Bong Jun, Do Hyung Kim, Timothy J. Griffin

Research output: Contribution to journalArticle

35 Citations (Scopus)

Abstract

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 upregulated 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.

Original languageEnglish (US)
Pages (from-to)403-414
Number of pages12
JournalMolecular and Cellular Proteomics
Volume9
Issue number2
DOIs
StatePublished - Feb 1 2010

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Sirolimus
Proteomics
DNA Damage
DNA
Ataxia Telangiectasia
Phosphorylation
HeLa Cells
Proteins
Chemical activation
Survival
Cell growth
Substrates
Nutritional Status
Nutrients
Mass spectrometry
Mass Spectrometry
Cell Survival
Homeostasis
Phosphotransferases
Down-Regulation

Cite this

Quantitative nuclear proteomics identifies mTOR regulation of DNA damage response. / Bandhakavi, Sricharan; Kim, Young Mi; Ro, Seung Hyun; Xie, Hongwei; Onsongo, Getiria; Jun, Chang Bong; Kim, Do Hyung; Griffin, Timothy J.

In: Molecular and Cellular Proteomics, Vol. 9, No. 2, 01.02.2010, p. 403-414.

Research output: Contribution to journalArticle

Bandhakavi, Sricharan ; Kim, Young Mi ; Ro, Seung Hyun ; Xie, Hongwei ; Onsongo, Getiria ; Jun, Chang Bong ; Kim, Do Hyung ; Griffin, Timothy J. / Quantitative nuclear proteomics identifies mTOR regulation of DNA damage response. In: Molecular and Cellular Proteomics. 2010 ; Vol. 9, No. 2. pp. 403-414.
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