AIRE recruits P-TEFb for transcriptional elongation of target genes in medullary thymic epithelial cells.
AIRE is a transcriptional activator that directs the ectopic expression of many tissue-specific genes in medullary thymic epithelial cells, which plays an important role in the negative selection of autoreactive T cells. However, its mechanism of action remains poorly understood. In this study, we found that AIRE regulates the step of elongation rather than initiation of RNA polymerase II. For these effects, AIRE bound and recruited P-TEFb to target promoters in medullary thymic epithelial cells. In these cells, AIRE activated the ectopic transcription of insulin and salivary protein 1 genes. Indeed, by chromatin immunoprecipitation, we found that RNA polymerase II was already engaged on these promoters but was unable to elongate in the absence of AIRE. Moreover, the genetic inactivation of cyclin T1 from P-TEFb abolished the transcription of AIRE-responsive genes and led to lymphocytic infiltration of lacrimal and salivary glands in the CycT1-/- mouse. Our findings reveal critical steps by which AIRE regulates the transcription of genes that control central tolerance in the thymus.
Oven
Irena
I
Department of Medicine, Rosalind Russell Medical Research Center, University of California-San Francisco, San Francisco, California 94143-0703, USA.
Brdicková
Nadezda
N
Kohoutek
Jiri
J
Vaupotic
Tomaz
T
Narat
Mojca
M
Peterlin
B Matija
BM
D000818:Animals; D016213:Cyclins / Q000172:deficiency; D004847:Epithelial Cells / Q000201:enzymology / Q000378:metabolism*; D005786:Gene Expression Regulation; D006367:HeLa Cells; D006801:Humans; D051379:Mice; D042925:Positive Transcriptional Elongation Factor B / Q000378:metabolism*; D011401:Promoter Regions, Genetic / Q000235:genetics; D012319:RNA Polymerase II / Q000378:metabolism; D016601:RNA-Binding Proteins / Q000378:metabolism; D013950:Thymus Gland / Q000166:cytology* / Q000201:enzymology / Q000378:metabolism*; D014157:Transcription Factors / Q000378:metabolism*; D014158:Transcription, Genetic; D015533:Transcriptional Activation; D000096927:AIRE Protein
D016213:Cyclins; D042925:Positive Transcriptional Elongation Factor B; D012319:RNA Polymerase II; D016601:RNA-Binding Proteins; D014157:Transcription Factors; D000096927:AIRE Protein