Influence of the human immunodeficiency virus type 1 Tat protein on the proliferation and differentiation of PC12 rat pheochromocytoma cells.
Rat pheochromocytoma PC12 cells were permanently transfected with a plasmid vector, containing the tat gene of human immunodeficiency virus type 1 (HIV-1). Various clones were obtained showing the production of different levels of bioactive Tat protein (Tat) after transient cotransfection with an HIV-1 long terminal repeat-chloramphenicol acetyltransferase reporter plasmid. Under conditions of serum starvation, tat-positive PC12 clones expressing high levels of Tat showed a significantly (P < 0.05) higher proliferation rate with respect to both mock-transfected PC12 cells and tat-positive PC12 cells expressing lower levels of Tat. Moreover, all tat-positive PC12 cell clones showed a partial morphological differentiation into sympathetic-like neurons, when seeded in low density (5 x 10(3) cells/cm2) cultures. On the other hand, mock-transfected PC12 cells showed the round shaped morphology typical of untreated PC12 cells and displayed signs of neuronal differentiation only after treatment with 100 ng/ml of nerve growth factor. The addition of 5 micrograms/ml of anti-Tat monoclonal antibody to the culture medium of tat-positive PC12 cell clones almost completely blocked their increased proliferation rate (P < 0.05), but did not affect neuronal differentiation. A significant (P < 0.05) increase in cell proliferation was consistently observed in PC12 cells supplemented with low concentrations of Tat (5 to 25 ng/ml), whereas neuronal differentiation was hardly affected by exogenous Tat. Our data strongly suggest that Tat exerts a complex influence on the proliferation and differentiation of PC12 cells, and this might help in increasing understanding of the pathogenesis of the frequent neurological disorders observed in AIDS patients.
Milani
D
D
Institute of Human Anatomy, University of Ferrara, Italy.
Zauli
G
G
Neri
L M
LM
Marchisio
M
M
Previati
M
M
Capitani
S
S
D000818:Animals; D002454:Cell Differentiation / Q000187:drug effects; D002455:Cell Division / Q000187:drug effects; D002999:Clone Cells; D004305:Dose-Response Relationship, Drug; D015696:Gene Products, tat / Q000235:genetics / Q000494:pharmacology*; D015497:HIV-1 / Q000235:genetics; D015850:Interleukin-6 / Q000494:pharmacology*; D009414:Nerve Growth Factors / Q000494:pharmacology*; D009474:Neurons / Q000166:cytology; D016716:PC12 Cells / Q000187:drug effects*; D051381:Rats; D011994:Recombinant Proteins / Q000494:pharmacology; D013564:Sympathetic Nervous System / Q000166:cytology / Q000254:growth & development*; D054322:tat Gene Products, Human Immunodeficiency Virus
D015696:Gene Products, tat; D015850:Interleukin-6; D009414:Nerve Growth Factors; D011994:Recombinant Proteins; D054322:tat Gene Products, Human Immunodeficiency Virus