Human papillomavirus type 16 E7 oncoprotein binds and inactivates growth-inhibitory insulin-like growth factor binding protein 3.
The E7 protein encoded by human papillomavirus type 16 is one of the few viral genes that can immortalize primary human cells and thereby override cellular senescence. While it is generally assumed that this property of E7 depends on its interaction with regulators of the cell cycle, we show here that E7 targets insulin-like growth factor binding protein 3 (IGFBP-3), the product of a p53-inducible gene that is overexpressed in senescent cells. IGFBP-3 can suppress cell proliferation and induce apoptosis; we show here that IGFBP-3-mediated apoptosis is inhibited by E7, which binds to IGFBP-3 and triggers its proteolytic cleavage. Two transformation-deficient mutants of E7 failed to inactivate IGFBP-3, suggesting that inactivation of IGFBP-3 may contribute to cell transformation.
Deutsches Krebsforschungszentrum, Forschungsschwerpunkt Angewandte Tumorvirologie, INF 242, D-69120 Heidelberg, Germany.
B
B
Mannhardt
S A
SA
Weinzimer
M
M
Wagner
M
M
Fiedler
P
P
Cohen
P
P
Jansen-Dürr
W
W
Zwerschke
D017209:Apoptosis; D015152:Blotting, Northern; D002455:Cell Division; D002460:Cell Line; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D005455:Fluorescent Antibody Technique; D005982:Glutathione Transferase / Q000378:metabolism; D006801:Humans; D018972:Insulin-Like Growth Factor Binding Protein 3 / Q000037:antagonists & inhibitors* / Q000378:metabolism*; D015603:Keratinocytes / Q000378:metabolism; D009856:Oncogene Proteins, Viral / Q000235:genetics* / Q000378:metabolism*; D050725:Papillomavirus E7 Proteins; D011233:Precipitin Tests; D011485:Protein Binding; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D013997:Time Factors; D014162:Transfection; D014407:Tumor Cells, Cultured; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism; D020798:Two-Hybrid System Techniques
D018972:Insulin-Like Growth Factor Binding Protein 3; D009856:Oncogene Proteins, Viral; D050725:Papillomavirus E7 Proteins; D011993:Recombinant Fusion Proteins; D016159:Tumor Suppressor Protein p53; C059731:oncogene protein E7, Human papillomavirus type 16; D005982:Glutathione Transferase