Robust mRNA transcription in chicken DT40 cells depleted of TAF(II)31 suggests both functional degeneracy and evolutionary divergence.
We have employed gene targeting coupled with conditional expression to construct a chicken DT40 cell line in which a tetracycline (Tet)-repressible promoter is exclusively responsible for expression of cTAF(II)31, a histone-like TAF(II) residing in both the transcription factor TFIID and the histone acetylase complex PCAF/SAGA. Tet addition resulted in rapid loss of cTAF(II)31 mRNA and protein, eventually leading to apoptotic cell death. Significantly, five of six other TAF(II)s tested were also rapidly depleted, but levels of the TATA binding protein and subunits of PCAF/SAGA were at most modestly compromised. Strikingly, pulse-labeling experiments indicate that total poly(A)(+) mRNA transcription was not significantly reduced after cTAF(II)31 depletion, and steady-state levels of several specific transcripts remained the same or decreased only mildly. Moreover, activation of c-fos transcription following serum starvation occurred efficiently in the absence of cTAF(II)31. These data, which contrast with comparable studies in yeast, strongly suggest that cTAF(II)31 and perhaps other TAF(II)s are not essential for general mRNA transcription in DT40 cells. We propose that this is due to extensive functional degeneracy in the highly complex metazoan transcriptional machinery.
Chen
Z
Z
Department of Biological Sciences, Columbia University, New York, New York 10027, USA.
Manley
J L
JL
D000123:Acetyltransferases / Q000235:genetics / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D017209:Apoptosis / Q000235:genetics; D002453:Cell Cycle / Q000235:genetics; D002455:Cell Division / Q000187:drug effects / Q000235:genetics; D002460:Cell Line / Q000187:drug effects; D002645:Chickens; D003001:Cloning, Molecular; D003470:Culture Media; D004257:DNA Polymerase II / Q000235:genetics / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D019143:Evolution, Molecular; D051548:Histone Acetyltransferases; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism; D011401:Promoter Regions, Genetic; D012333:RNA, Messenger / Q000235:genetics; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D012097:Repressor Proteins / Q000187:drug effects / Q000235:genetics; D029701:Saccharomyces cerevisiae Proteins; D017386:Sequence Homology, Amino Acid; D035381:TATA-Binding Protein Associated Factors; D035181:TATA-Box Binding Protein; D013752:Tetracycline / Q000494:pharmacology; D015534:Trans-Activators / Q000235:genetics* / Q000378:metabolism*; D035362:Transcription Factor TFIID; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D014158:Transcription, Genetic
D003470:Culture Media; D004268:DNA-Binding Proteins; D009687:Nuclear Proteins; D012333:RNA, Messenger; D011994:Recombinant Proteins; D012097:Repressor Proteins; D029701:Saccharomyces cerevisiae Proteins; C087176:TAF2 protein, S cerevisiae; C100838:TAF5 protein, human; C106849:TAF9 protein, human; D035381:TATA-Binding Protein Associated Factors; D035181:TATA-Box Binding Protein; D015534:Trans-Activators; D035362:Transcription Factor TFIID; D014157:Transcription Factors; C034811:tetracycline resistance-encoding transposon repressor protein; D000123:Acetyltransferases; D051548:Histone Acetyltransferases; C069001:TATA-binding protein associated factor 250 kDa; D004257:DNA Polymerase II; D013752:Tetracycline