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Promoter‐specific functions of CIITA and the MHC class II enhanceosome in transcriptional activation
Author(s) -
Masternak Krzysztof,
Reith Walter
Publication year - 2002
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.1093/emboj/21.6.1379
Subject(s) - biology , ciita , genetics , mhc class ii , regulation of gene expression , microbiology and biotechnology , gene , major histocompatibility complex
Transcription of the major histocompatibility complex class II family of genes is regulated by conserved promoter elements and two gene‐specific trans‐activators, RFX and CIITA. RFX binds DNA and nucleates the assembly of an enhanceosome, which recruits CIITA through protein–protein interactions. Transcriptional activation is a complex, multi‐step process involving chromatin modification and recruitment of the transcription apparatus. To examine the roles of the enhanceosome and CIITA in these processes, we analysed the level of promoter‐associated hyperacetylated histones H3 and H4, TBP, TFIIB and RNA poly merase II in cells lacking RFX or CIITA. We compared four genes co‐regulated by RFX and CIITA ( HLA‐DRA , HLA‐DPB , HLA‐DMB and Ii ) and found that the enhanceosome and CIITA make variable, promoter‐dependent contributions to histone acetylation and transcription apparatus recruitment. CIITA is generally implicated at multiple levels of the activation process, while the enhanceosome contributes in a CIITA‐independent manner only at certain promoters. Our results support the general notion that the impact of a particular activator on transcription in vivo may vary depending on the promoter and the chromatin context.