This Article
Right arrow Full Text
Right arrow Full Text (PDF)
Right arrow Supplemental material
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrowReprints and Permissions
Right arrow Copyright Information
Right arrow Books from ASM Press
Right arrow MicrobeWorld
Citing Articles
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Brush, M. H.
Right arrow Articles by Shenolikar, S.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Brush, M. H.
Right arrow Articles by Shenolikar, S.

 Previous Article  |  Next Article 

Molecular and Cellular Biology, December 2008, p. 6989-7000, Vol. 28, No. 23
0270-7306/08/$08.00+0     doi:10.1128/MCB.00724-08
Copyright © 2008, American Society for Microbiology. All Rights Reserved.

Control of Cellular GADD34 Levels by the 26S Proteasome {triangledown} ,{dagger}

Matthew H. Brush{ddagger} and Shirish Shenolikar*

Department of Pharmacology and Cancer Biology, Duke University Medical Center, Durham, North Carolina 27710

Received 6 May 2008/ Returned for modification 22 July 2008/ Accepted 8 September 2008

GADD34, the product of a growth arrest and DNA damage-inducible gene, is expressed at low levels in unstressed cells. In response to stress, the cellular content of GADD34 protein increases and, on termination of stress, rapidly declines. We investigated the mechanisms that control GADD34 levels in human cells. GADD34 proteins containing either an internal FLAG or a C-terminal green fluorescent protein epitope were degraded at rates similar to endogenous GADD34. However, the addition of epitopes at the N terminus or deletion of N-terminal sequences stabilized GADD34. N-terminal peptides of GADD34, either alone or fused to heterologous proteins, exhibited rapid degradation similar to wild-type GADD34, thereby identifying an N-terminal degron. Deletion of internal PEST repeats had no impact on GADD34 stability but modulated the binding and activity of protein phosphatase 1. Proteasomal but not lysosomal inhibitors enhanced GADD34 stability and eukaryotic initiation factor 2{alpha} (eIF-2{alpha}) dephosphorylation, a finding consistent with GADD34's role in assembling an eIF-2{alpha} phosphatase. GADD34 was polyubiquitinated, and this modification enhanced its turnover in cells. A stabilized form of GADD34 promoted the accumulation and aggregation of the mutant cystic fibrosis transmembrane conductance regulator (CFTR{Delta}F508), highlighting the physiological importance of GADD34 turnover in protein processing in the endoplasmic reticulum and the potential impact of prolonged GADD34 expression in human disease.

* Corresponding author. Present address: Duke-NUS Graduate Medical School Singapore, 2 Jalan Bukit Merah, Singapore 169547. Phone: (65) 6516 2588. Fax: (65) 6220 8161. E-mail: shirish.shenolikar{at}duke-nus.edu.sg

{triangledown} Published ahead of print on 15 September 2008.

{dagger} Supplemental material for this article may be found at http://mcb.asm.org/.

{ddagger} Present address: Vollum Institute, Oregon Health and Science University, 3181 S.W. Sam Jackson Park Road, Portland, OR 97239.

Molecular and Cellular Biology, December 2008, p. 6989-7000, Vol. 28, No. 23
0270-7306/08/$08.00+0     doi:10.1128/MCB.00724-08
Copyright © 2008, American Society for Microbiology. All Rights Reserved.





Copyright © 2009 by the American Society for Microbiology.   For an alternate route to Journals.ASM.org, visit: http://intl-journals.asm.org | More Info»