Antiretroviral nucleosides, deoxynucleotide carrier and mitochondrial DNA: evidence supporting the DNA pol gamma hypothesis

• Type of Material: Article
• Authors: William Lewis, Emory University; James J Kohler, Emory University; Seyed H. Hosseini, Emory University; Chad P. Haase, Emory University; William C. Copeland, National Institute of Environmental Health Sciences; Rachelle J. Bienstock, National Institute of Environmental Health Sciences; Tomika Ludaway, Emory University; Jamie McNaught, Emory University; Rodney Russ, Emory University; Tami Stuart, Emory University; Robert Santoianni, Emory University
• Language: English
• Date: 2006-03-21
• Publisher: Lippincott, Williams & Wilkins
• Publication Version: Author Accepted Manuscript (After Peer Review)
• Copyright Statement: © 2006 Lippincott Williams & Wilkins, Inc.
• Final Published Version (URL): http://journals.lww.com/aidsonline/pages/articleviewer.aspx?year=2006&issue=03210&article=00006&type=abstract
• Title of Journal or Parent Work: AIDS
• ISSN: 0269-9370
• Volume: 20
• Issue: 5
• Start Page: 675
• End Page: 684
• Grant/Funding Information: This work was supported by DHHS, NIH NHLBI R01 HL072707, R01 HL059798, and R01 HL063666 to W.L. and intramural NIH funds to W.C.C and R.J.B. Brian Hoit is thanked for his insightful comments on this manuscript.
• Keywords: deoxynucleotide carrier; cardiomyopathy; AIDS; mitochondria; DNA polymerase; heart; nucleoside reverse transcriptase inhibitor; transgenic
• Research Categories: Health Sciences, Pathology; Environmental Sciences

Abstract

Design Nucleoside reverse transcriptase inhibitors (NRTIs) exhibit mitochondrial toxicity. The mitochondrial deoxynucleotide carrier (DNC) transports nucleotide precursors (or phosphorylated NRTIs) into mitochondria for mitochondrial (mt)DNA replication or inhibition of mtDNA replication by NRTIs. Transgenic mice (TG) expressing human DNC targeted to murine myocardium served to define mitochondrial events from NRTIs in vivo and findings were corroborated by biochemical events in vitro. Methods Zidovudine (3′-azido-2′,3′-deoxythymidine; ZDV), stavudine (2′, 3′-didehy-dro-2′, 3′-deoxythymidine; d4T), or lamivudine ((−)-2′-deoxy-3′-thiacytidine; 3TC) were administered individually to TGs and wild-type (WT) littermates (35 days) at human doses with drug-free vehicle as control. Left ventricle (LV) mass was defined echocardiographically, mitochondrial ultrastructural defects were identified by electron microscopy, the abundance of cardiac mtDNA was quantified by real time polymerase chain reaction, and mtDNA-encoded polypeptides were quantified. Results Untreated TGs exhibited normal LV mass with minor mitochondrial damage. NRTI monotherapy (either d4T or ZDV) increased LV mass in TGs and caused significant mitochondrial destruction. Cardiac mtDNA was depleted in ZDV and d4T-treated TG hearts and mtDNA-encoded polypeptides decreased. Changes were absent in 3TC-treated cohorts. In supportive structural observations from molecular modeling, ZDV demonstrated close contacts with K947 and Y951 in the DNA pol γ active site that were absent in the HIV reverse transcriptase active site. Conclusions NRTIs deplete mtDNA and polypeptides, cause mitochondrial structural and functional defects in vivo, follow inhibition kinetics with DNA pol γ in vitro, and are corroborated by molecular models. Disrupted pools of nucleotide precursors and inhibition of DNA pol γ by specific NRTIs are mechanistically important in mitochondrial toxicity.