HIV viral protein R causes atrial cardiomyocyte mitosis, mesenchymal tumor, dysrhythmia, and heart failure

Abstract

HIV viral protein R (Vpr) affects the immunocyte cell cycle and circulates as free polypeptide in plasma of AIDS patients. Effects of Vpr on cardiomyocytes were explored using transgenic mice (TG) with Vpr targeted to cardiomyocytes by the a-myosin heavy-chain promoter. TG and WT littermate hearts were evaluated histopathologically, ultrastructurally, molecularly via RNA microarray analysis and quantitative RT-PCR, and functionally by cardiac magnetic resonance imaging (MRI) and electrocardiograms (ECG). Six hemizygous lines were created (Vpr a,b,c,d,e,h ). Vpr RNA was expressed exclusively in myocardium and Vpr mRNA expression correlated with phenotypic changes. Vpr b exhibited the highest expression and mortality. TGs developed congestive heart failure (E8 weeks), abnormal cardiomyocyte nuclei and mitoses (E12 weeks), and became moribund (E20 weeks) with atrial mesenchymal tumors. MRI revealed four-chamber dilation, defective contraction, and atrial masses. Pathologically, cardiomegaly and atrial mesenchymal tumors occurred (E16-20 weeks). ECGs showed prolonged R-R, Q-T, and P-R intervals (E12 weeks). RNA encoding collagen and bone morphogenic protein 4, 6, and 7 were increased. Vpr targeted to cardiomyocytes caused defective contractility and atrial tumors. Since some Vpr cardiomyocytic effects resemble those found in terminally differentiated immunocytes, some pathogenetic mechanisms may be shared at the subcellular level.

Targeted Transgenic Overexpression of Mitochondrial Thymidine Kinase (TK2) Alters Mitochondrial DNA (mtDNA) and Mitochondrial Polypeptide Abundance

“…32 A murine transgenic approach helped unravel some features of AIDS heart disease. 27,33,34 Clinically relevant changes were found related to HIV gene products, 16,18 and to antiretroviral therapy in models in which defective mitochondrial biogenesis related to drug toxicity. 35 In the present study, cytosolic TK1 and mitochondrial TK2 isoforms each were individually overexpressed in the murine heart.…”

“…Established methods were used essentially as described previously 13,14,16,18 and applied to the TK1 and TK2 cDNA constructs from Wang and Eriksson. 19 -22 The resulting constructs contained the N-terminal mt signal sequence (in case of murine TK2 22 ) and the intact N-and C-terminal cDNA sequences (in the case of human TK1).…”

Cardiac-Targeted Transgenic Mutant Mitochondrial Enzymes: mtDNA Defects, Antiretroviral Toxicity and Cardiomyopathy

“…For the two TK2 mutants (H121N and I212N), the presence of the transgene was detected in the founders and their offspring using Southern blotting and real-time PCR essentially as reported in the past [13,18]. Pol c Y955C TGs were routinely verified as described previously [15].…”

Decreased mtDNA, oxidative stress, cardiomyopathy, and death from transgenic cardiac targeted human mutant polymerase γ

“…27,29,31,32 Genotyping For the TG line a-MyHC/Y955C, the presence of the mutant transgene was detected in the founders and their offspring using Southern blotting and real-time PCR essentially as recently described. 27,29,32 TG Gene Copy Analysis Four transgenic lines were established for the targeted overexpression of mutant POLG. To determine the relative copy number in each, the level of human Y955C POLG was analyzed semiquantitatively from tail DNA extracts using realtime PCR and Light Cycler TaqMan Master kit.…”

“…The effect of human Y955C Pol g on the murine heart was explored using transgenically targeted Y955C POLG driven by the alpha myosin heavy chain promoter (aMyHC). This transgenic approach was pioneered by Robbins, 26 and was adapted and used successfully by us in the past 22,[27][28][29] and in studies here. Cardiac targeted Y955C POLG yielded expression of abundant but enzymatically defective Pol g polypeptide in TG hearts.…”