Sr. Opalenik et al., THE HIV-1 TAT PROTEIN INDUCES THE EXPRESSION AND EXTRACELLULAR APPEARANCE OF ACIDIC FIBROBLAST GROWTH-FACTOR, The Journal of biological chemistry, 270(29), 1995, pp. 17457-17467
Mounting experimental evidence suggests that the TAT protein, released
from human immunodeficiency virus-1 (HIV-1)-infected inflammatory cel
ls, may genetically reprogram targeted cells within a localized enviro
nment to develop highly vascularized tumors of mesenchymal origin. The
fibroblast growth factor (FGF) family of polypeptides has gained gene
ral acceptance as initiators of angiogenesis and functions as potent m
ito gens for mesoderm-derived cells. To evaluate a potential biologica
l relationship between TAT and acidic FGF (FGF-1), primary murine embr
yonic fibroblasts either were transfected with the viral transactivato
r or were transduced (retrovirally mediated) with a secreted, chimeric
form of the human polypeptide growth factor, human stomach tumor/Kapo
si's sarcoma (hst/KS)FGF-1. Reverse transcriptase-polymerase chain rea
ction, Western blotting, in situ immunohistochemical, heparin affinity
, DNA synthesis, and transient transfection techniques were used to co
nfirm expression, localization, and functionality of the transgenes, B
oth transfected and transduced cells constitutively expressing either
TAT or (hst/KS)FGF-1 adopted a transformed phenotype, maintained aggre
ssive growth behavior, and demonstrated both induction of EGF-specific
phosphotyrosyl proteins and nuclear association of FGF-1 and FGF-1 re
ceptor. Increased levels of endogenous, murine FGF 1 mRNA (reverse tra
nscriptase-polymerase chain reaction) and protein (immunoblot analysis
) were apparent in both (hst/KS)FGF-1- and TAT-transformed cells, Medi
um conditioned by (hst/KS)FGF-1-transduced cells contained steady-stat
e levels of biologically active FGF-1 which exhibited a representative
molecular weight. Limited sodium dodecyl sulfate-polyacrylamide gel e
lectrophoretic 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 ex
pression and secretion of FGF-1, which may be potentially relevant to
the pathophysiological development of AIDS-Kaposi's sarcoma.