Role of the cyclic AMP response element in the bcl-2 promoter in the regulation of endogenous Bcl-2 expression and apoptosis in murine B cells.
We have previously shown for B-cell lines that the cyclic AMP response element (CRE) is a major positive regulatory site in the bcl-2 promoter. However, the role of the CRE in the regulation of endogenous bcl-2 expression in vivo has not been characterized. We used gene targeting to generate knock-in mice in which a mutated CRE was introduced into the bcl-2 promoter region (mutCRE-bcl2 mice). Quantitative chromatin immunoprecipitation assays revealed that mutation of the CRE abolished the binding of CREB/ATF and CBP transcription factors to the bcl-2 promoter and greatly diminished the binding of NF-kappaB factors. The mutant CRE significantly reduced the expression of Bcl-2 in B cells and rendered them susceptible to surface immunoglobulin- and chemotherapeutic agent-induced apoptosis. The low levels of Bcl-2 were not changed with activation of the cells. The numbers of pre-B, immature B, and mature B cells in the bone marrow were decreased, as were the numbers of splenic B cells in mutCRE-bcl2 mice. Our findings indicate that the CRE in the bcl-2 promoter has an important functional role in the regulation of endogenous Bcl-2 expression and plays a critical role in the coordination of signals that regulate B-cell survival.
Xiang
Hong
H
Center for Molecular Biology in Medicine, Veterans Affairs Palo Alto Health Care System, and Department of Medicine, Stanford University School of Medicine, Stanford, CA 94305-5156, USA.
Wang
Jinghong
J
Boxer
Linda M
LM
D000818:Animals; D017209:Apoptosis; D001402:B-Lymphocytes / Q000378:metabolism*; D001665:Binding Sites; D017362:Cyclic AMP Response Element-Binding Protein / Q000235:genetics / Q000378:metabolism; D005786:Gene Expression Regulation; D008213:Lymphocyte Activation; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D011401:Promoter Regions, Genetic; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000235:genetics / Q000378:metabolism*; D013154:Spleen / Q000166:cytology / Q000378:metabolism; D014157:Transcription Factors / Q000378:metabolism; D014158:Transcription, Genetic; D014162:Transfection
D017362:Cyclic AMP Response Element-Binding Protein; D019253:Proto-Oncogene Proteins c-bcl-2; D014157:Transcription Factors