The retinoblastoma gene family members pRB and p107 coactivate the AP-1-dependent mouse tissue factor promoter in fibroblasts.

Abstract

Serum-stimulation of quiescent mouse fibroblasts results in transcriptional activation of tissue factor (TF), the cellular initiator of blood coagulation. This requires the rapid entry of c-Fos into specific AP-1 DNA-binding complexes and can be strongly inhibited by the adenovirus EIA 12S gene product. In this study, we utilized a panel of E1A mutants deficient in cellular protein binding to analyse the molecular basis for EIA inhibition of a minimal, c-Fos-dependent TF promoter/ reporter construct in mouse AKR-2B fibroblasts. Mutations which impaired binding of the retinoblastoma tumor suppressor protein family members pRB, p107, and p130 relieved E1A-mediated inhibition of transcription in response to serum-stimulation or c-Fos overexpression. Inhibition was restricted to the G0 to G1 transition, consistent with the specificity of E1A for hypophosphorylated forms of RB proteins. Although E1A mutants deficient in CBP/p300 binding retained the ability to inhibit TF transcription, deletion of the amino-terminal portion of the CBP/p300 interaction domain was required to permit rescue of TF promoter activity by coexpression of pRB. Moreover, ectopic p107 could effectively substitute for pRB in relieving E1A-mediated repression. In primary mouse embryo fibroblasts, activity of the minimal AP-1-dependent TF promoter was suppressed in Rb(-/-) cells compared to parallel Rb(+/-) and Rb(+/+) transfectants. Ectopic expression of either pRB or p107 markedly enhanced TF promoter activity in Rb(-/-) fibroblasts. Collectively, these data imply that pRB and p107 can cooperate with c-Fos to activate TF gene transcription in fibroblasts and suggest a requirement for another, as yet unidentified, E1A-binding protein.

• Authors: S L Liu, A Rand, R J Kelm Jr, M J Getz
• Journal: Oncogene (Oncogene) Vol. 19 Issue 30 Pg. 3352-62 (Jul 13 2000) ISSN: 0950-9232 [Print] England
• PMID: 10918592 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't, Research Support, U.S. Gov't, P.H.S.)

Chemical References

• Adenovirus E1A Proteins
• Membrane Glycoproteins
• Nuclear Proteins
• Phosphoproteins
• Proteins
• Proto-Oncogene Proteins c-fos
• Rbl1 protein, mouse
• Rbl2 protein, mouse
• Receptors, Cell Surface
• Retinoblastoma Protein
• Retinoblastoma-Like Protein p107
• Retinoblastoma-Like Protein p130
• Trans-Activators
• Transcription Factor AP-1
• Thromboplastin

Topics

• Adenovirus E1A Proteins (genetics, metabolism)
• Animals
• Binding Sites
• Cell Line
• Fibroblasts (cytology, metabolism)
• Membrane Glycoproteins (genetics, metabolism)
• Mice
• Mutagenesis
• Nuclear Proteins (genetics, metabolism)
• Phosphoproteins (metabolism)
• Promoter Regions, Genetic
• Proteins
• Proto-Oncogene Proteins c-fos (genetics, metabolism)
• Receptors, Cell Surface (genetics, metabolism)
• Retinoblastoma Protein (genetics, metabolism)
• Retinoblastoma-Like Protein p107
• Retinoblastoma-Like Protein p130
• Thromboplastin (metabolism)
• Trans-Activators (genetics, metabolism)
• Transcription Factor AP-1 (metabolism)