1: EMBO J. 2002 Mar 15;21(6):1379-88. 

Promoter-specific functions of CIITA and the MHC class II enhanceosome in
transcriptional activation.

Masternak K, Reith W.

Department of Genetics and Microbiology, University of Geneva Medical School, 1
rue Michel-Servet, CH-1211 Geneve 4, Switzerland.

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.

PMID: 11889043 [PubMed - indexed for MEDLINE]


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2: Nature. 1995 Apr 27;374(6525):822-3. 

Stimulation of RNA polymerase II transcription initiation by recruitment of TBP
in vivo.

Klages N, Strubin M.

Department of Genetics and Microbiology, University Medical Centre (CMU),
Geneva, Switzerland.

Eukaryotic transcriptional activators may stimulate RNA polymerase II activity
by promoting assembly of preinitiation complexes on promoters through their
interactions with one or more components of the basal machinery. On the basis of
its central role in initiating transcription-complex formation upon binding to
the TATA box, the general transcription factor TFIID, which includes the
TATA-binding protein (TBP) and several TBP-associated factors, has been
implicated as a target for activators. Consistent with this idea, an increasing
number of activators have been reported to bind directly to TBP. To assess the
functional importance of these in vitro interactions for transcriptional
regulation in vivo, we made use of a novel strategy in yeast to show that a
physical interaction with TBP is sufficient for a sequence-specific DNA-binding
protein to increase initiation of transcription by RNA polymerase II. These
results imply that binding of TFIID to promoter elements is a limiting step in
transcription complex assembly in vivo.

PMID: 7723829 [PubMed - indexed for MEDLINE]


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