Ets-1 positively regulates Fas ligand transcription via cooperative interactions with Sp1.
The FasL/Fas system has been implicated in smooth muscle cell apoptosis and atherosclerotic plaque instability, a process that can lead to plaque rupture, precipitating myocardial infarction and sudden death. The transcriptional mechanisms regulating FasL gene expression in vascular smooth muscle cells are poorly understood. We recently described a novel mechanism mediating inducible FasL gene expression in smooth muscle cells involving the zinc finger transcription factor Sp1 (Kavurma, M. M., Santiago, F. S., Bofocco, E., and Khachigian, L. M. (2001) J. Biol. Chem. 276, 4964-4971). We now show that FasL gene expression is governed by cooperative activation between Sp1 and the Ets family of transcription factors. The overexpression of Ets-1 was sufficient to induce FasL promoter-dependent expression and protein synthesis. Ets-1 activation of the promoter was abrogated either by deletion or mutation of the Sp1 binding site. The overexpression of Ets-1 together with Sp1 produced cooperative activation of the FasL promoter. Sp1 induction of the FasL promoter was abrogated by an Ets-1 mutant lacking the activation domain. Conversely, Ets-1 activation of the promoter was blocked by an Sp1 mutant bearing the DNA-binding domain. The mutation of the (-365)GGAA(-362) element in the FasL promoter abolished Ets-1 activation and attenuated Sp1-inducible gene expression. Immunoprecipitation and supershift experiments revealed that endogenous Ets-1 and Sp1 physically interact and co-occupy this site. Thus, FasL gene expression in vascular smooth muscle cells is mediated by cooperativity between Ets-1 and Sp1.
Kavurma
Mary M
MM
Centre for Thrombosis and Vascular Research and Surgical Professional Unit, St. Vincents Hospital, The University of New South Wales, Sydney 2052, Australia.
Bobryshev
Yuri
Y
Khachigian
Levon M
LM
D001161:Arteriosclerosis / Q000378:metabolism; D001483:Base Sequence; D001665:Binding Sites; D015153:Blotting, Western; D002339:Carotid Arteries / Q000473:pathology; D002460:Cell Line; D003850:Deoxyribonuclease I / Q000378:metabolism; D004730:Endothelium, Vascular / Q000166:cytology; D053222:Fas Ligand Protein; D017353:Gene Deletion; D005786:Gene Expression Regulation; D006801:Humans; D007150:Immunohistochemistry; D020287:In Situ Nick-End Labeling; D008156:Luciferases / Q000378:metabolism; D008562:Membrane Glycoproteins / Q000378:metabolism*; D008954:Models, Biological; D008969:Molecular Sequence Data; D009130:Muscle, Smooth / Q000166:cytology; D009154:Mutation; D010766:Phosphorylation; D010957:Plasmids / Q000378:metabolism; D011233:Precipitin Tests; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D050784:Proto-Oncogene Protein c-ets-1; D011518:Proto-Oncogene Proteins / Q000378:metabolism*; D050783:Proto-Oncogene Proteins c-ets; D016329:Sp1 Transcription Factor / Q000378:metabolism*; D013997:Time Factors; D014157:Transcription Factors / Q000378:metabolism*; D014158:Transcription, Genetic; D014162:Transfection; D016335:Zinc Fingers
C494041:ETS1 protein, human; C505661:FASLG protein, human; D053222:Fas Ligand Protein; D008562:Membrane Glycoproteins; D050784:Proto-Oncogene Protein c-ets-1; D011518:Proto-Oncogene Proteins; D050783:Proto-Oncogene Proteins c-ets; D016329:Sp1 Transcription Factor; D014157:Transcription Factors; D008156:Luciferases; D003850:Deoxyribonuclease I