HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

J. Biol. Chem., Vol. 280, Issue 12, 10888-10896, March 25, 2005

This Article Full Text Full Text (PDF) All Versions of this Article: 280/12/10888    most recent M409064200v1 Submit a Letter to Editor Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Permissions Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Shi, Q. Articles by Gibson, G. E. Search for Related Content PubMed PubMed Citation Articles by Shi, Q. Articles by Gibson, G. E. Social Bookmarking                      What's this?

Reduction in the E2k Subunit of the -Ketoglutarate Dehydrogenase Complex Has Effects Independent of Complex Activity^*

Qingli Shi, Huan-Lian Chen, Hui Xu, and Gary E. Gibson

From the Department of Neurology and Neuroscience, Weill Medical College of Cornell University at Burke Medical Research Institute, White Plains, New York 10605

The activity of the -ketoglutarate dehydrogenase complex (KGDHC) declines in brains of patients with several neurodegenerative diseases. KGDHC consists of multiple copies of E1k, E2k, and E3. E1k and E2k are unique to KGDHC and may have functions independent of the complex. The present study tested the consequences of different levels of diminished E2k mRNA on protein levels of the subunits, KGDHC activity, and physiological responses. Human embryonic kidney cells were stably transfected with an E2k sense or antisense expression vector. Sense control (E2k-mRNA-100) was compared with two clones in which the mRNA was reduced to 67% of control (E2k-mRNA-67) or to 30% of control (E2k-mRNA-30). The levels of the E2k protein in clones paralleled the reduction in mRNA, and E3 proteins were unaltered. Unexpectedly, the clone with the greatest reduction in E2k protein (E2k-mRNA-30) had a 40% increase in E1k protein. The activity of the complex was only 52% of normal in E2k-mRNA-67 clone, but was near normal (90%) in E2k-mRNA-30 clone. Subsequent experiments tested whether the physiological consequences of a reduction in E2k mRNA correlated more closely to E2k protein or to KGDHC activity. Growth rate, increased DCF-detectable reactive oxygen species, and cell death in response to added oxidant were proportional to E2k proteins, but not complex activity. These results were not predicted because subunits unique to KGDHC have never been manipulated in mammalian cells. These results suggest that in addition to its essential role in metabolism, the E2k component of KGDHC may have other novel roles.

Received for publication, August 9, 2004 , and in revised form, January 12, 2005.

^* This work was supported by National Institutes of Health Grants AG14600, AG14930, and AG11921. The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked "advertisement" in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.

To whom correspondence should be addressed: Dept. of Neurology and Neuroscience, Weill Medical College of Cornell University at Burke Medical Research Institute, 785 Mamaroneck Ave., White Plains, NY 10605. Tel.: 914-597-2291; Fax: 914-597-2757; E-mail: ggibson{at}med.cornell.edu.

CiteULike    Complore    Connotea    Del.icio.us    Digg    Reddit    Technorati    What's this?

This article has been cited by other articles:

				H. Liu, L. Liu, B. S. Fletcher, and G. A. Visner Novel Action of Indoleamine 2,3-Dioxygenase Attenuating Acute Lung Allograft Injury Am. J. Respir. Crit. Care Med., March 1, 2006; 173(5): 566 - 572. [Abstract] [Full Text] [PDF]

				D. Mandal, A. Mazumder, P. Das, M. Kundu, and J. Basu Fas-, Caspase 8-, and Caspase 3-dependent Signaling Regulates the Activity of the Aminophospholipid Translocase and Phosphatidylserine Externalization in Human Erythrocytes J. Biol. Chem., November 25, 2005; 280(47): 39460 - 39467. [Abstract] [Full Text] [PDF]

				S. W. Sauer, J. G. Okun, M. A. Schwab, L. R. Crnic, G. F. Hoffmann, S. I. Goodman, D. M. Koeller, and S. Kolker Bioenergetics in Glutaryl-Coenzyme A Dehydrogenase Deficiency: A ROLE FOR GLUTARYL-COENZYME A J. Biol. Chem., June 10, 2005; 280(23): 21830 - 21836. [Abstract] [Full Text] [PDF]