PMID:20937824

Citation	Devaiah, BN, Lu, H, Gegonne, A, Sercan, Z, Zhang, H, Clifford, RJ, Lee, MP and Singer, DS (2010) Novel functions for TAF7, a regulator of TAF1-independent transcription. J. Biol. Chem. 285:38772-80
Abstract	The transcription factor TFIID components TAF7 and TAF1 regulate eukaryotic transcription initiation. TAF7 regulates transcription initiation of TAF1-dependent genes by binding to the acetyltransferase (AT) domain of TAF1 and inhibiting the enzymatic activity that is essential for transcription. TAF7 is released from the TAF1-TFIID complex upon completion of preinitiation complex assembly, allowing transcription to initiate. However, not all transcription is TAF1-dependent, and the role of TAF7 in regulating TAF1-independent transcription has not been defined. The IFNγ-induced transcriptional co-activator CIITA activates MHC class I and II genes, which are vital for immune responses, in a TAF1-independent manner. Activation by CIITA depends on its intrinsic AT activity. We now show that TAF7 binds to CIITA and inhibits its AT activity, thereby repressing activated transcription. Consistent with this TAF7 function, siRNA-mediated depletion of TAF7 resulted in increased CIITA-dependent transcription. A more global role for TAF7 as a regulator of transcription was revealed by expression profiling analysis: expression of 30-40% of genes affected by TAF7 depletion was independent of either TAF1 or CIITA. Surprisingly, although TAF1-dependent transcripts were largely down-regulated by TAF7 depletion, TAF1-independent transcripts were predominantly up-regulated. We conclude that TAF7, until now considered only a TFIID component and regulator of TAF1-dependent transcription, also regulates TAF1-independent transcription.
Links	PubMed PMC2998114 Online version:10.1074/jbc.M110.173864
Keywords	Animals; CHO Cells; Cricetinae; Cricetulus; Drosophila; Gene Expression Profiling; Gene Expression Regulation; Gene Expression Regulation, Neoplastic; HeLa Cells; Humans; Interferon-gamma/metabolism; Nuclear Proteins/metabolism; Pol1 Transcription Initiation Complex Proteins/metabolism; RNA, Small Interfering/metabolism; TATA-Binding Protein Associated Factors/physiology; Trans-Activators/metabolism; Transcription Factor TFIID/physiology; Transcription, Genetic
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Annotations

Gene product	Qualifier	GO Term	Evidence Code	with/from	Aspect	Extension	Notes	Status
HUMAN:TAF7		GO:0090241: negative regulation of histone H4 acetylation	ECO:0000314:		P		Figure 2 shows that TAF7 purified from HeLa cells decreased CIITA-mediated acetylation of histone 4. Increasing concentrations of TAF7 resulted in lower acetylation of H4.	complete CACAO 12219
HUMAN:TAF7		GO:0045344: negative regulation of MHC class I biosynthetic process	ECO:0000314:		P		Figure 3A shows that TAF7 prevents the transcription of MHC class I promoters in HeLa cells. This process prevents the biosynthesis of MHC class I molecules. No TAF7 mutants were used to obtain this conclusion.	complete CACAO 12220
HUMAN:TAF7		GO:0045347: negative regulation of MHC class II biosynthetic process	ECO:0000315:		P		Figure 4 shows that HeLa cells with siRNA knowckdown of TAF7 expressed elevated levels of MHC class II genes (DRA and DRB). Therefore, TAF7 negatively regulates the biosynthesis of MHC class II molecules.	complete CACAO 12221

References

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