Interleukin-1 induces growth arrest by hypophosphorylation of the retinoblastoma susceptibility gene product RB.
Interleukin-1 (IL-1) causes G0/G1 phase growth arrest in human melanoma cells, A375-C6. Because hypophosphorylation of the retinoblastoma susceptibility gene product, RB, is one of the key events responsible for G0/G1 phase growth arrest, we investigated whether IL-1 altered the phosphorylation status of RB protein in these cells. Exposure to IL-1 caused a time-dependent increase in hypophosphorylated RB that correlated with an accumulation of cells arrested in the G0/G1 phase. The ability of IL-1 to cause hypophosphorylation of RB and growth arrest was abrogated by the SV40 large T antigen, which binds preferentially to hypophosphorylated RB, but not by the K1 mutant of the T antigen, which is defective in binding to RB. Furthermore, the cells were protected from IL-1-inducible growth inhibition by ectopic expression of dominant-negative mutants of the Rb gene, or the transcription factor E2F-1, which is a downstream target of RB. These results suggest that hypophosphorylated RB mediates the growth arrest induced by IL-1.
Muthukkumar
S
S
Department of Surgery, University of Kentucky, Lexington, 40536, USA.
Sells
S F
SF
Crist
S A
SA
Rangnekar
V M
VM
D000952:Antigens, Polyomavirus Transforming / Q000096:biosynthesis; D002352:Carrier Proteins; D002453:Cell Cycle / Q000187:drug effects; D018797:Cell Cycle Proteins; D002455:Cell Division / Q000187:drug effects; D002460:Cell Line; D004268:DNA-Binding Proteins; D050684:E2F Transcription Factors; D050687:E2F1 Transcription Factor; D005434:Flow Cytometry; D016193:G1 Phase; D015870:Gene Expression / Q000187:drug effects; D016161:Genes, Retinoblastoma; D006801:Humans; D007375:Interleukin-1 / Q000494:pharmacology*; D007700:Kinetics; D008545:Melanoma; D010766:Phosphorylation; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000494:pharmacology; D016192:Resting Phase, Cell Cycle; D016160:Retinoblastoma Protein / Q000096:biosynthesis / Q000187:drug effects / Q000378:metabolism*; D056465:Retinoblastoma-Binding Protein 1; D013539:Simian virus 40 / Q000235:genetics; D013936:Thymidine / Q000378:metabolism; D013997:Time Factors; D050680:Transcription Factor DP1; D014157:Transcription Factors / Q000096:biosynthesis; D014162:Transfection; D014407:Tumor Cells, Cultured; D014409:Tumor Necrosis Factor-alpha / Q000187:drug effects
D000952:Antigens, Polyomavirus Transforming; D002352:Carrier Proteins; D018797:Cell Cycle Proteins; D004268:DNA-Binding Proteins; D050684:E2F Transcription Factors; D050687:E2F1 Transcription Factor; C493753:E2F1 protein, human; D007375:Interleukin-1; D011994:Recombinant Proteins; D016160:Retinoblastoma Protein; D056465:Retinoblastoma-Binding Protein 1; D050680:Transcription Factor DP1; D014157:Transcription Factors; D014409:Tumor Necrosis Factor-alpha; D013936:Thymidine