The HIV-1 TAT Protein Induces the Expression and Extracellular Appearance of Acidic Fibroblast Growth Factor (*)
- From the Division of Transplantation, Department of Surgery, School of Medicine, University of Alabama at Birmingham, Birmingham, Alabama 35294
- ¶ To whom correspondence should be addressed: Division of Transplantation, Dept. of Surgery, School of Medicine, University of Alabama at Birmingham, UAB Station, Birmingham, AL 35294 .
Abstract
Mounting experimental evidence suggests that the TAT protein, released from human immunodeficiency virus-1 (HIV-1)-infected inflammatory cells, may genetically reprogram targeted cells within a localized environment to develop highly vascularized tumors of mesenchymal origin. The fibroblast growth factor (FGF) family of polypeptides has gained general acceptance as initiators of angiogenesis and functions as potent mitogens for mesoderm-derived cells. To evaluate a potential biological relationship between TAT and acidic FGF (FGF-1), primary murine embryonic fibroblasts either were transfected with the viral transactivator or were transduced (retrovirally mediated) with a secreted, chimeric form of the human polypeptide growth factor, human stomach tumor/Kaposi's sarcoma (hst/KS)FGF-1. Reverse transcriptase-polymerase chain reaction, Western blotting, in situ immunohistochemical, heparin affinity, DNA synthesis, and transient transfection techniques were used to confirm expression, localization, and functionality of the transgenes. Both transfected and transduced cells constitutively expressing either TAT or (hst/KS)FGF-1 adopted a transformed phenotype, maintained aggressive growth behavior, and demonstrated both induction of FGF-specific phosphotyrosyl proteins and nuclear association of FGF-1 and FGF-1 receptor. Increased levels of endogenous, murine FGF-1 mRNA (reverse transcriptase-polymerase chain reaction) and protein (immunoblot analysis) were apparent in both (hst/KS)FGF-1- and TAT-transformed cells. Medium conditioned by (hst/KS)FGF-1-transduced cells contained steady-state levels of biologically active FGF-1 which exhibited a representative molecular weight. Limited sodium dodecyl sulfate-polyacrylamide gel electrophoretic analysis of the conditioned medium from TAT-transformed cells demonstrated the appearance of FGF-1 as latent, high molecular weight complexes requiring reducing agents to activate full biological activity. Collectively, these results suggest that TAT induces the expression and secretion of FGF-1, which may be potentially relevant to the pathophysiological development of AIDS-Kaposi's sarcoma.
Footnotes
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↵§ Supported by National Research Service Award Fellowship HL08391.
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↵* This work was supported in part by National Institutes of Health Grants HL45990 and HL48491. Synthesis of oligonucleotide linkers and amplimers was supported by NCI Grant CA13148 to the University of Alabama at Birmingham Comprehensive Cancer Center. These studies were performed in partial fulfillment of the requirement for the Ph.D. degree from the Departments of Medical Genetics (S. R. O.) and Biochemistry/Molecular Genetics (J. T. S.), University of Alabama at Birmingham. The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore by hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
The nucleotide sequence(s) reported in this paper has been submitted to the GenBank®/EMBL Data Bank with accession number(s) U26456[GenBank® Link].
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↵1 The abbreviations used are:
- HIV-1
-
human immunodeficiency virus-1
- LTR
-
long terminal repeat
- KS
-
Kaposi's sarcoma
- IL
-
interleukin
- AIDS
-
acquired immunodeficiency syndrome
- FGF-1 and −2
-
acidic and basic fibroblast growth factor, respectively
- FGFR
-
fibroblast growth factor receptor
- hst/KS
-
human stomach tumor/Kaposi's sarcoma
- bp
-
base pair(s)
- DMEM
-
Dulbecco's modified Eagle's medium
- FBS
-
fetal bovine serum
- FACS
-
fluorescence-activated cell sorting
- PBS
-
phosphate-buffered saline
- DTT
-
dithiothreitol
- PCR
-
polymerase chain reaction
- PAGE
-
polyacrylamide gel electrophoresis
- BrdU
-
bromodeoxyuridine.
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↵2J. T. Shin, S. R. Opalenik, J. N. Wehby, V. K. Mahesh, A. Jackson, F. Tarantini, T. Maciag, and J. A. Thompson, submitted for publication.
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- Received October 21, 1994.
- Revision received May 12, 1995.
