A role for Elongin in Mediator recruitment at ATF6α regulated genes [RNA-Seq]

The bZIP transcription factor ATF6α is a master regulator of endoplasmic reticulum (ER) stress response genes. In this report, we identify the multifunctional RNA polymerase II transcription factor Elongin as a cofactor for ATF6α-dependent transcription activation. Biochemical studies reveal that Elongin functions at least in part by facilitating ATF6α-dependent loading of Mediator at the promoters and enhancers of ER stress response genes. Depletion of Elongin from cells leads to impaired transcription of ER stress response genes and to defects in the recruitment of Mediator and, in particular, its CDK8 kinase subunit. Taken together, these findings bring to light a new role for Elongin as a loading factor for Mediator during the ER stress response. RNA-seq of polyA-selected libraries prepared from HCT116 cells