Regulation of transcript elongation through cooperative and ordered recruitment of cofactors.
We studied the regulation of murine CD80, a gene whose basal transcriptional status was characterized by the presence of a stalled RNA polymerase II complex on the promoter-proximal region. Stimulus-induced activation of productive elongation involved a complex interplay of regulated events that included a synergy between ordered cofactor recruitment. This cascade of recruitments was initiated through the engagement of transcription factor NF-kappaB, leading to the temporal association of histone acetyltransferases and the consequent selective acetylation of a transcription start site downstream nucleosome. This in turn culminated into the nucleosomal association of Brd4-associated P-TEFb, a protein complex containing kinase specific for serine 2 of Rbp 1, the largest subunit of the carboxyl-terminal domain of RNA polymerase II. The consequent phosphorylation of serine 2 residues in CTD by CDK9 in the P-TEFb complex then facilitated escape of polymerase II into the productive elongation phase. Thus, the cooperative mechanisms that integrate between independent pathways characterize regulation of the elongation step of transcription, thereby providing another level at which specificity of gene regulation can be achieved.
Sharma
Manish
M
Immunology Group, International Centre for Genetic Engineering and Biotechnology, Aruna Asaf Ali Marg, New Delhi 110067, India.
George
Anuja A
AA
Singh
Badri N
BN
Sahoo
Naresh C
NC
Rao
Kanury V S
KV
D000818:Animals; D018122:B7-1 Antigen / Q000737:chemistry / Q000378:metabolism; D019013:CD40 Antigens / Q000096:biosynthesis; D042863:Cyclin-Dependent Kinase 9 / Q000378:metabolism; D005786:Gene Expression Regulation; D051379:Mice; D008954:Models, Biological; D008957:Models, Genetic; D016328:NF-kappa B / Q000378:metabolism; D009707:Nucleosomes / Q000378:metabolism; D010766:Phosphorylation; D042925:Positive Transcriptional Elongation Factor B / Q000378:metabolism; D011401:Promoter Regions, Genetic; D012319:RNA Polymerase II / Q000378:metabolism*; D015854:Up-Regulation
D018122:B7-1 Antigen; D019013:CD40 Antigens; D016328:NF-kappa B; D009707:Nucleosomes; D042925:Positive Transcriptional Elongation Factor B; C467972:Cdk9 protein, mouse; D042863:Cyclin-Dependent Kinase 9; D012319:RNA Polymerase II