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Am J Physiol Heart Circ Physiol 282: H1672-H1678, 2002; doi:10.1152/ajpheart.00955.2001
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Vol. 282, Issue 5, H1672-H1678, May 2002

Targeted myocardial transgenic expression of HIV Tat causes cardiomyopathy and mitochondrial damage

Scott M. Raidel1, Chad Haase1, Natalie R. Jansen1, Rodney B. Russ1, Roy L. Sutliff1, Leonard W. Velsor2, Brian J. Day2, Brian D. Hoit3, Allen M. Samarel4, and William Lewis1

1 Emory University School of Medicine, Atlanta, Georgia 30322; 2 National Jewish Medical Center, Denver, Colorado 80206; 3 University Hospital Cleveland, Cleveland, Ohio 44106; 4 Stritch School of Medicine, Loyola University Chicago, Maywood, Illinois 60153


    ABSTRACT
TOP
ABSTRACT
INTRODUCTION
EXPERIMENTAL PROCEDURES
RESULTS
DISCUSSION
REFERENCES

Cardiac effects of human immunodeficiency virus (HIV) transactivator (Tat) are unclear, but Tat decreases liver glutathione (an important mitochondrial antioxidant) when ubiquitously expressed in transgenic mice (TG). With an alpha -myosin heavy chain promoter, Tat was selectively targeted to murine cardiac myocytes. One high-expression hemizygous (+/-Tathigh; 12 copies) and two low-expression (+/-TatlowA,B; 2-5 copies) TG lines were created. Cardiomyopathy was documented with increased left ventricle (LV) mass, ventricular expression of atrial natriuretic factor (ANF) mRNA, mitochondrial ultrastructural defects, and myocardial depletion of glutathione. In +/-Tathigh TGs, normalized LV mass (determined echocardiographically) increased 46% (90 days), 134% (240 days), and 96% (365 days) compared with wild-type littermates (WT). LV fractional shortening was decreased to 28% (90 days), 27% (240 days), and 19% (365 days). +/-Tatlow LV mass was unchanged (<= 365 days). ANF in +/-Tathigh ventricles (180 days) was twofold WT values. Glutathione was selectively decreased in +/-Tathigh hearts (120 days). +/-Tathigh hearts contained damaged mitochondria (>= 210 days); however, profound mitochondrial destruction occurred in homozygous +/+Tathigh hearts (10 days) and the pups died (14 days). Tat caused cardiac dysfunction in this TG and may impact on cardiomyopathy in acquired immunodeficiency syndrome.

acquired immunodeficiency syndrome; cardiac dysfunction; echocardiogram; oxidative stress; transmission electron microscopy


    INTRODUCTION
TOP
ABSTRACT
INTRODUCTION
EXPERIMENTAL PROCEDURES
RESULTS
DISCUSSION
REFERENCES

CARDIOMYOPATHY (CM) is an important cardiac complication in acquired immunodeficiency syndrome (AIDS) (4, 6). Postulated etiologies of AIDS CM include direct human immunodeficiency virus (HIV) infection of the heart (4, 19, 32) after myocarditis (26), toxicity of AIDS therapeutics (11, 29, 31), effects of alcohol or drugs (34), cytokine effects on cardiac performance (5), and comorbid conditions (3). More than one cause may be operative in the same patient (reviewed in Refs. 27, 28).

HIV Tat serves as a transactivator that stimulates transcription and is required for efficient HIV replication (reviewed in Ref. 17). Tat can activate heterologous promoters and mediate activities of cellular functions. Extracellular Tat promotes growth of spindle cells derived from Kaposi's sarcoma and normal vascular cells (2, 15). Tat contributes to the activation of endothelial cells and the expression of endothelial cell adhesion molecules (12, 20).

HIV has been demonstrated in cardiac myocytes in AIDS (4, 19, 32). However, the cardiac effects of Tat are poorly understood. Tat may impact on drug toxicity and cause oxidative damage in organs and has been shown to decrease glutathione (GSH) content in livers of transgenic mice (TG) (9). In light of these effects, our working hypothesis states that Tat impacts directly on myocardial cellular function in AIDS patients and contributes to AIDS CM. Experiments in the present study explored the effect of Tat on the structure and function of the cardiac myocyte and of the heart.

Previously, HIV Tat was ubiquitously and nonspecifically expressed in TG with various promoters (e.g., beta -actin promoter) (7-10, 18, 25, 35, 40). However, those TG models examined Tat effects in noncardiac tissues, lacked tissue targeting, exhibited no Tat myocardial expression, or exhibited Tat expression in multiple tissues without examining cardiac effects. Accordingly, cardiac effects (if any) from ubiquitous TG expression of Tat could result from systemic, local, or combined effects of Tat expression.

Experiments here targeted expression of Tat to cardiac myocytes and focused on changes in myocytic and cardiac structure and function that resulted from Tat expression. An established TG strategy (33, 37) was used to specifically target HIV Tat to murine cardiac myocytes. Selective expression of HIV Tat in the myocardium increased left ventricular (LV) mass, decreased ventricular fractional shortening (FS), caused mitochondrial destruction, altered ventricular expression of fetal gene products, and resulted in selective depletion of cardiac GSH. These TG effects worsened over time, and oxidative stress may be a central subcellular event. The data indicate that Tat depressed cardiac contractility in TGs and could contribute to AIDS CM in patients.


    EXPERIMENTAL PROCEDURES
TOP
ABSTRACT
INTRODUCTION
EXPERIMENTAL PROCEDURES
RESULTS
DISCUSSION
REFERENCES

Generation of alpha -myosin heavy chain/Tat TGs. Established methods were used. A 1.304-kb HindIII-SmaI fragment containing both exons of Tat (86-residue polypeptide) and an intron from the rat preproinsulin gene (ppI) was isolated from clone pBC12/CMV/Tat-1 (a generous gift from Andrew P. Rice, Univ. of Texas Southwestern Medical Center, Dallas, TX). The fragment was modified with Klenow enzyme (Boehringer, Mannheim, Germany) to fill in the HindIII site. The alpha -myosin heavy chain (alpha -MyHC) clone 26 (compliments of Jeff Robins, Children's Research Foundation, Cincinnati, OH; Ref. 39) was digested with SalI and then modified with Klenow enzyme followed by treatment with shrimp alkaline phosphatase (Boehringer) to facilitate construction of the final vector. Restriction analysis and DNA sequencing verified the final construct, denoted alpha -MyHC/Tat. To generate TGs, a 7.4-kb NotI-NotI fragment containing the full transcriptional unit was purified and microinjected into FVB one-cell embryos (Charles River, Wilmington, MA). Embryos were implanted into pseudopregnant CD-1 females (Taconic, Germantown, NY). The resulting offspring were screened for incorporation of the transgene. One high-expression hemizygous (+/-Tathigh) and two low-expression hemizygous (+/-TatlowA,B) TG lines were created. All mice were housed according to National Institutes of Health guidelines and fed ad libitum.

Genotyping. The alpha -MyHC/Tat transgene was detected in the founders and their offspring with Southern blotting and PCR. For Southern blotting, 10 µg of mouse genomic tail DNA was digested overnight at 37°C. The digested DNA was subjected to electrophoresis in a 0.7% agarose gel and transferred to a positively charged nylon membrane (Boehringer) overnight. Hybridization was performed in a solution containing 6× SSC (1× SSC: 150 mmol/l NaCl, 15 mmol/l Na citrate), 1% SDS, 10% dextran sulfate, 100 µg/ml salmon sperm DNA, and 32P-labeled Tat cDNA at 68°C overnight. The membranes were then washed once in 2× SSC-1% SDS at room temperature for 15 min and twice in 0.1× SSC-0.1% SDS at 68°C for 30 min and exposed to a storage phosphor screen (Packard Instrument, Meriden, CT). Detection was performed on a Cyclone storage phosphor system (Packard Instrument). Genotyping of the progeny from the founders was accomplished by PCR. Fifty nanograms of mouse genomic tail DNA was used along with primers TAT1 (5'GGAGCCAGTAGATCCTAGACTAGAGCC-3') and TAT2 (5'CCTCCACCCAGCTCCAGTTGTGC-3'), which were designed to detect the presence of the targeted TG. They produced a product of 1.1 kb. PCR was preformed in a 20-µl volume with Taq DNA polymerase (Boehringer) in a PTC100 thermal cycler (MJ Research, Watertown, MA) with the following conditions: 5 min at 95°C, followed by 30 cycles of 30 s at 95°C, 30 s at 55°C, 1 min at 72°C, ending with a 3-min extension at 72°C and then 4°C.

RNA extraction and Northern blot analysis. Methods resembled those used by us previously (30). Total RNA was extracted from tissues of 60-day-old mice with TRI reagent (Molecular Research, Cincinnati, OH). RNA (10 µg) was subjected to electrophoresis with the NorthernMax kit (Ambion, Austin, TX) in a 1% agarose gel and transferred to a positively charged nylon membrane enzyme (Boehringer) overnight. Hybridization was performed in ULTRAhyb (Ambion) containing either 32P-labeled Tat cDNA or 32P-labeled glyceraldehyde-3-phosphate dehydrogenase (GAPDH) cDNA transcripts at 42°C overnight. The membranes were then washed twice in 2× SSC-0.1% SDS at 42° for 5 min and twice in 0.1× SSC-0.1% SDS at 42° for 15 min and exposed to a storage phosphor screen (Packard Instrument). Detection was preformed on a Cyclone storage phosphor system (Packard Instrument). mRNA was isolated from total RNA samples with the Poly(A) Pure kit (Ambion). Two micrograms of mRNA was subjected to electrophoresis as above and hybridized with probes for TAT and GAPDH.

Cardiac mRNA analysis of +/-TGhigh and wild-type littermates at 180 days. Total RNA was isolated from LV tissue samples from 60- and 180-day wild-type (WT) and +/-Tathigh littermates (n = 3 per cohort) by established methods (14, 30). Northern blots were probed with 32P-labeled cDNA probes specific for atrial natriuretic factor (ANF; 0.8-kb cDNA fragment of rat ANF courtesy of T. Inagama, Vanderbilt University, Nashville, TN) and specific for sarco(endo)plasmic reticulum Ca2+-ATPase (SERCA2; 2.3-kb cDNA fragment of the rat cardiac SERCA2 provided by Dr. W. Dillmann, University of California at San Diego). Equal loading and uniformity of transfer were insured by normalizing hybridization signal intensity to that of GAPDH mRNA. cDNA probes were radiolabeled and hybridized as previously described (14). The amount of each respective mRNA relative to the amount of GAPDH mRNA was quantified by autoradiography at -80°C, and signals were quantitatively analyzed by a Packard Instrument Cyclone storage phosphor system.

Protein extraction and Western blot analysis. Total protein was isolated from 60-day WT, +/-Tathigh, and +/-TatlowA hearts with T-PER tissue protein extraction reagent (Pierce, Rockford, IL). Each protein sample (100 µg) was electrophoresed though SDS-18% Tris · HCl polyacrylamide gel (Bio-Rad, Hercules, CA). The resolved proteins were transferred to an Immun-Blot polyvinylidene difluoride membrane (Bio-Rad), blocked with 5% nonfat dry milk in Tris-buffered saline (TBS), and incubated with a mouse monoclonal antibody to HIV Tat (Advanced Biotechnologies, Columbia, MD) 1:4,000 in 2% milk-TBS overnight at 4°C. After four washes in TBS-Tween 20, the membrane was incubated with horseradish peroxidase-linked sheep anti-mouse immunoglobulin G (Amersham, Piscataway, NJ) 1:20,000 in 2% milk-TBS for 30 min. The membrane was washed four more times and incubated with SuperSignal West Femto substrate (Pierce). The membrane was exposed to BioMax film (Kodak, Rochester, NY) for 5 min and developed.

HPLC analysis for antioxidants in heart and quadriceps femoris muscle. GSH and ascorbate (Asc) in heart and quadriceps femoris muscle (WT, +/-Tathigh; n = 6/cohort; 120 days) were analyzed by HPLC coupled with coulometric electrochemical detection (CoulArray model 5600; ESA, Chelmsford, MA). Sample analysis was done with a 7 × 53-mm C-18 reverse phase (Platinum EPS C18 100A 3 µm; Altech Associates, Deerfield, IL) and a mobile phase of 125 mM potassium acetate in 1% acetonitrile at pH of 3.0. The electrode potentials in a four-channel electrode array were set at 100, 270, 620, and 730 mV. Under these conditions, Asc and GSH exhibited retention times of 2.82 and 3.14 min, respectively. Antioxidant concentrations were determined from a 5-µl injection and based on a five-point standard curve generated with freshly prepared standards.

Echocardiography. Echocardiographic studies were performed serially in WT and +/-Tathigh and +/-TatlowA TGs (90, 240, and 365 days) essentially as described previously (21, 30). At least three sequential measurements were obtained (n = 3-16 per cohort).

Transmission electron microscopy. Methods were as described previously (30). Each heart provided ~10 samples for embedding. Myocardium was rinsed in cold Ringer solution and postfixed in 1% OsO4 (Sigma, St. Louis, MO) in PBS, pH 7.4. for 2-3 h. After osmication and rinses, tissue was dehydrated with graded ethanols and embedded in resin (38). Myocardial samples were sectioned (100 nm), stained with uranyl acetate, and examined on a JEOL-JEM-100CX electron microscope. Photomicrographs were enlarged to 8 × 10-in. prints and reviewed for the presence of structurally abnormal mitochondria (as done previously; Ref. 30).

Statistical analysis. Groups were compared by ANOVA as previously described (30). Significance was established with P < 0.05.


    RESULTS
TOP
ABSTRACT
INTRODUCTION
EXPERIMENTAL PROCEDURES
RESULTS
DISCUSSION
REFERENCES

Tissue specificity of RNA expression. A transgenic mouse was created that expressed HIV Tat in the heart and that developed a pathophysiological cardiovascular phenotype. Northern analysis of total RNA from different tissues from +/-Tathigh TGs revealed significant levels of Tat RNA only in the heart and the absence of signal in other tissues (Fig. 1A). Northern analysis of RNA extracted from +/-TatlowA revealed similar tissue specificity (data not shown).


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  		Fig. 1.   A: Northern blot analysis of RNA from tissues from high- expression hemizygous (+/-Tathigh) transgenic mice (TGs). Significant levels of Tat RNA were found in the heart. Conversely, Tat RNA was absent in all other tissues examined. Quad, quadriceps femoris; GAPDH, glyceraldehyde-3-phosphate dehydrogenase. B: Northern blot analysis of polyadenylated mRNA in the TG lines. Collage Northern blot follows histogram labels. C: histogram of quantitative molecular data obtained from +/-Tathigh, +/+Tathigh, and low-expression hemizygous (+/-TatlowA) TGs (n = 2 for each). Signal for Tat mRNA in +/+Tathigh is twofold that of +/-Tathigh. D: Western blot of extracted myocardial polypeptides from WT, +/-Tathigh, and +/-TatlowA purified Tat (external control). No signal for Tat is found in wild-type mice (WT). Extract from +/-Tathigh and +/-TatlowA hearts shows clear signal for Tat.

TAT mRNA expression. Northern analysis of Tat mRNA showed strong signal in blots from +/-Tathigh and +/+Tathigh TGs (Fig. 1B). Quantitation of Northern blot signals for cardiac polyadenylated RNA encoding Tat revealed threefold expression of transcribed Tat mRNA in +/-Tathigh hearts compared with +/-TatlowA hearts (Fig. 1C). Expression in +/+Tathigh pup hearts was twice that of +/-Tathigh TG.

Tat polypeptide expression in WT, +/-Tathigh, and +/-TatlowA mice. Extracted polypeptides from hearts of WT, +/-Tathigh, and +/-TatlowA mice underwent electrophoresis, transfer, and Western blotting. The data showed Tat polypeptide signal in the Western blots of myocardial extracts from TGs with characteristic electrophoretic mobility of Tat (Fig. 1D). Tat signal was absent in myocardial extract from WT littermates (Fig. 1D). Samples from representative 60-day +/-Tathigh and +/-TatlowA mice revealed strong signals in the myocardial extracts (Fig. 1D). Purified Tat served as an external standard (Fig. 1D).

mRNA markers of ventricular remodeling. Characteristic molecular changes of cardiac remodeling were found in RNA extracts from hearts of 180d +/-Tathigh mice (Fig. 2A). GAPDH was the internal control. By quantitative analysis of the radioactive signals, a twofold increase in steady-state abundance of ANF mRNA was found in ventricular samples from +/-Tathigh TGs versus WTs (Fig. 2B). Signal for SERCA2 was unchanged. In cardiac ventricular RNA extracts from +/-Tathigh TGs (60 days), steady-state abundance of ANF was unchanged compared with that of WT littermates (data not shown).


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  		Fig. 2.   Northern analysis (A) and histogram of quantitative molecular data (B) for +/-Tathigh TGs and WT littermates at 180 days. Steady-state abundance of atrial natriuretic factor (ANF) RNA was dramatically increased in hearts from +/-Tathigh compared with WT (* P < 0.05). Sarco(endo)plasmic reticulum Ca2+-ATPase (SERCA2) mRNA abundance was unchanged. Quantitative analysis (B) reveals 200% increase in ANF signal compared with WT littermates.

Steady-state abundance of antioxidants in heart and quadriceps femoris muscle. Steady-state abundance of GSH and Asc was determined in heart and quadriceps femoris samples from 120-day +/-Tathigh and WT littermates (Table 1). GSH abundance (nmol/mg protein) in heart samples from +/-Tathigh mice was 2.9 ± 0.4 (means ± SE) compared with 4.7 ± 0.8 in WT littermates (Table 1; P < 0.05). Steady-state abundance of Asc in the myocardium was unchanged. Similarly, steady-state abundance of GSH and Asc in quadriceps femoris muscle samples from +/-Tathigh mice was unchanged from the respective values in WT littermates (Table 1).

                              
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  		Table 1.   Antioxidants in +/-Tathigh and wild-type tissues

Transmission electron microscopy of heart muscle. Cardiac mitochondrial features were striking and included destruction, enlargement, and loss of cristae in homozygous +/+Tathigh TGs at 10 days (Fig. 3). In contrast, significant but less prominent mitochondrial structural defects (which worsened with increasing age) were found in hemizygous +/-Tathigh TGs. At 60 days, samples from +/-Tathigh TG hearts revealed essentially normal mitochondria. However, at 210-365 days, cardiac mitochondrial damage and enlargement were unambiguous (Fig. 3). Mitochondria from hearts of WT littermates were essentially normal (Fig. 3, bottom). Mitochondria from quadriceps femoris samples were normal in +/-Tathigh mice (data not shown).


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  		Fig. 3.   Ultrastructural features of hearts from +/+Tathigh and +/-Tathigh TGs. Collage of myocardial samples from +/-Tathigh mice at 60, 210, and 365 days. At 60 days, cardiac mitochondria from +/-Tathigh are structurally unremarkable (top right) and resemble those of WT (top left). At 210 days, +/-Tathigh mitochondrial transmission electron microscopy (middle left) reveals dissolution and disruption of cristae. At 365 days, +/-Tathigh mitochondrial damage includes abnormal division (middle right). At 10 days, +/+Tathigh mitochondria (bottom right) are enlarged and cristae are severely damaged compared with WT littermate (bottom left) (original magnification ×14,400 each).

Echocardiographic data from WT, +/-Tathigh, and +/-TatlowA mice. M-mode echocardiograms were performed and evaluated (single observer) on WT, +/-Tathigh, and +/-TatlowA mice (90, 240, and 365 days). LV thickening was found in the +/-Tathigh TGs after as little as 90 days. Quantitatively, +/-Tathigh TG hearts showed a 46% increase in LV mass at 90 days (P < 0.05), 134% increase at 240 days (P < 0.001), and 96% increase at 365 days (P < 0.001; Fig. 4A). Corresponding changes in LV FS were 28% at 90 days, 27% at 240 days, and 19% at 365 days (P < 0.001 for each comparison to WT littermates; Fig. 4B). Early in life, +/-Tathigh TG hearts revealed no change in LV mass (30 and 60 days; data not shown). Additionally, at comparable time points up to 365 days, echocardiograms of +/-TatlowA TGs showed no change in LV mass (data not shown).


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  		Fig. 4.   A: calculated left ventricular (LV) mass in +/-Tathigh mice. +/-Tathigh TGs revealed LV mass increased 46% (90 days; *P < 0.05), 134% (240 days; **P < 0.001), and 94% (365 days; **P < 0.001). B: calculated fractional shortening (FS) in +/-Tathigh and WT. FS decreased to 28% at 90 days, 27% at 240 days, and 19% at 365 days (*P < 0.001 for each comparison to WT littermate).


    DISCUSSION
TOP
ABSTRACT
INTRODUCTION
EXPERIMENTAL PROCEDURES
RESULTS
DISCUSSION
REFERENCES

A targeted TG with cardiac-specific expression of HIV Tat was created, and a cardiac pathophysiological phenotype resulted. To our knowledge, this is the first time an HIV gene has been selectively expressed transgenically in cardiac myocytes and the first time a cardiac phenotype resulted from its targeted expression.

In the past, nonspecific TG models of AIDS were generated (23, 24) in which various phenotypes were observed. One well-studied TG, the NL4-3Delta gag/pol (generalized expression of a replication-incompetent HIV construct), exhibited AIDS nephropathy prominently (13) and cardiac dysfunction (30). Recently, a TG rat was generated (with the same NL4-3Delta gag/pol construct) with AIDS nephropathy prominently and cardiac injury and repair (36). Multisystem disease could impact on cardiac function in these models.

In murine TGs with generalized expression of Tat, phenotypic manifestations included skin lesions, liver disease, lymphoid and other malignancies, and hematologic diseases (7-10, 18, 25, 35, 40). In contrast, our TG lines (operationally defined as +/-Tathigh, +/+Tathigh, and +/-TatlowA,B) offer the advantage of targeted Tat expression combined with an organ-specific phenotype. This allows us to monitor for organ dysfunction longitudinally in the living animal and to follow its natural history.

The TG lines +/-Tathigh and +/-TatlowA exhibited high and low Tat expression, respectively. +/-Tathigh and +/-TatlowA TG pups developed and matured normally, were fertile, exhibited normal litter size, and survived up to 2 years. In contrast, homozygous +/+Tathigh pups died prematurely at ~14 days. Ultrastructural pathological examination of hearts from +/+Tathigh pups euthanized at 10 days (i.e., ~4 days before typical death) revealed no gross structural abnormalities or inflammation. However, profound structural changes in cardiac mitochondria were found by transmission electron microscopy in samples from 10-day +/+Tathigh pups.

Pathophysiological findings in the +/-Tathigh TG followed a logical temporal sequence. Data suggest that from 90 to 210 days, cardiac remodeling occurs. At 60 days, robust Tat mRNA was expressed along with Tat polypeptide. At that time, ANF mRNA changes were absent. As early as 90 days, LV FS and LV mass changes of early cardiac dysfunction were found. At 120 days, GSH depletion was evident. At 180 days, ventricular expression of ANF (a sensitive marker of cardiac dysfunction; Ref. 22) was abundant. Transmission electron microscopy mitochondrial changes were unambiguous at 210 days and proceeded to 365 days. Common findings included cristae and matrix disruption, lamellar figures, incomplete fusion, or undivided mitochondria. These changes paralleled echocardiographic changes of CM. These combined structural and functional changes indicate that Tat caused a mitochondrial CM in which a cumulative threshold effect may be observed (41) that resembles the pathophysiology of some other forms of CM.

The pathophysiology of CM in this model suggests that oxidative stress plays a role. In TGs with ubiquitous Tat expression (driven by the beta -actin promoter), inhibition of glutathione synthase (9) and depletion of GSH occurred in the liver. Decreased GSH occurred selectively in +/-Tathigh TG hearts but not in WT hearts or quadriceps femoris samples from +/-Tathigh TGs. Asc was unchanged in both heart and quadriceps femoris in any cohort. These findings underscore a relationship between Tat, GSH depletion, and the cardiac-targeted TG phenotype. GSH is an important cellular antioxidant that can directly modulate cellular transcriptional events (1). Additionally, GSH is the only defense available in the mitochondria to metabolize hydrogen peroxide. Thus GSH depletion in this organelle renders cells more susceptible to oxidative stress (16).

M-mode echocardiograms and their quantitative analysis were used to define cardiac dysfunction with age in +/-Tathigh TGs. At 90 days, +/-Tathigh TGs exhibited LV enlargement, the earliest indication of cardiac dysfunction. LV enlargement and FS continued for the life of the +/-Tathigh TG. In contrast, +/-TatlowA LV function was unchanged up to 365 days. Survival in +/-Tathigh TGs was similar to that of WT littermates for >18 mo.

In summary, we successfully used the alpha -MyHC promoter to drive HIV Tat gene expression in ventricular cardiac myocytes and created a targeted AIDS TG mouse with cardiac dysfunction and CM. The echocardiographic phenotype began at 90 days and continued throughout life. Features of cardiac dysfunction included cardiomegaly, decreased FS, ventricular expression of ANF (a sensitive marker of cardiac dysfunction), and mitochondrial ultrastructural damage that worsened with age. Homozygote +/+Tathigh pups died at ~14 days with profound cardiac mitochondrial damage. Selective depletion of cardiac GSH links Tat to oxidative stress in this new murine transgenic model of AIDS CM. Future studies with this model may elucidate pathophysiological mechanisms of CM in AIDS and may suggest therapeutic options for treatment or prevention.


    ACKNOWLEDGEMENTS

The authors thank Robert Santoianni for thin sections and for photographic processing.


    FOOTNOTES

This work was supported by National Heart, Lung, and Blood Institute Grant R01-HL-59798 to W. Lewis.

Address for reprint requests and other correspondence: W. Lewis, Dept. of Pathology, Emory Univ. School of Medicine, 7117 Woodruff Memorial Bldg., 1639 Pierce Dr., Atlanta, GA 30322 (E-mail: wlewis{at}emory.edu).

The costs of publication of this article were defrayed in part by the payment of page charges. The article must therefore be hereby marked "advertisement" in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.

10.1152/ajpheart.00955.2001

Received 2 November 2001; accepted in final form 15 January 2002.


    REFERENCES
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ABSTRACT
INTRODUCTION
EXPERIMENTAL PROCEDURES
RESULTS
DISCUSSION
REFERENCES

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Am J Physiol Heart Circ Physiol 282(5):H1672-H1678
0363-6135/02 $5.00 Copyright © 2002 the American Physiological Society


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