QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) All Versions of this Article: mol.104.007120v1 67/2/408    most recent Submit a response Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Lam, W. Articles by Cheng, Y.-C. Search for Related Content PubMed PubMed Citation Articles by Lam, W. Articles by Cheng, Y.-C.

ORIGINAL ARTICLE

Expression of Deoxynucleotide Carrier Is Not Associated with the Mitochondrial DNA Depletion Caused by Anti-HIV Dideoxynucleoside Analogs and Mitochondrial dNTP Uptake

Department of Pharmacology, Yale University, New Haven, Connecticut

Abstract

Our previous studies suggested that the dNTP/dNDP transporter systems that exist in mitochondria for transporting dNTP/dNDP from the cytoplasm to the mitochondria for mitochondrial DNA (mtDNA) synthesis play a critical role in delayed cytotoxicity of anti-human immunodeficiency virus (HIV) dideoxynucleoside analogs in mitochondria. A protein, termed mitochondrial deoxynucleotide carrier (DNC), based on its ability to transport dNTPs in reconstituted proteoliposomes, was recently isolated. Lacking cellular information to substantiate DNC's involvement in the delayed cytotoxicity of dideoxynucleoside analogs, we expressed DNC and reconstituted it into proteoliposomes. The K_m values for dNTPs uptake by reconstituted DNC were in the millimolar range, which is a thousandfold higher than that of the physiological level. Furthermore, we found that overexpressing DNC (wt and G177A-mutated DNC) in RKO cells did not sensitize the cells to the mtDNA depletion caused by -D-2',3'-dideoxycytidine (ddC), 2',3'-didehydro-2',3'-dideoxythymidine, and 2',3'-dideoxyinosine or affect the mtDNA recovery rate after ddC treatment. Mitochondria isolated from DNC-overexpressing cells did not significantly differ from that isolated from RKO cells in terms of the rate of uptake or the incorporation of dTTP into mitochondria DNA. Down-regulation of DNC expression by small interfering RNA was also ineffective in changing the action of dideoxynucleoside analogs on the mtDNA depletion and the rate of dTTP uptake into isolated mitochondria. Down-regulation of both DNC and thymidine kinase-2 also did not cause mtDNA depletion. We conclude that DNC does not play an important role in the delayed cytotoxicity (mtDNA depletion) of anti-HIV dideoxynucleoside analogs and dNTPs uptake into mitochondria.

Address correspondence to: Dr. Yung-chi Cheng, Department of Pharmacology, Yale University School of Medicine, New Haven, CT 06520. E-mail: cheng.lab{at}yale.edu

This article has been cited by other articles:

				C. K. Mathews and S. Song Maintaining precursor pools for mitochondrial DNA replication FASEB J, August 1, 2007; 21(10): 2294 - 2303. [Abstract] [Full Text] [PDF]

				J. Satrustegui, B. Pardo, and A. del Arco Mitochondrial Transporters as Novel Targets for Intracellular Calcium Signaling Physiol Rev, January 1, 2007; 87(1): 29 - 67. [Abstract] [Full Text] [PDF]

				M. J. Lindhurst, G. Fiermonte, S. Song, E. Struys, F. De Leonardis, P. L. Schwartzberg, A. Chen, A. Castegna, N. Verhoeven, C. K. Mathews, et al. Knockout of Slc25a19 causes mitochondrial thiamine pyrophosphate depletion, embryonic lethality, CNS malformations, and anemia PNAS, October 24, 2006; 103(43): 15927 - 15932. [Abstract] [Full Text] [PDF]