Gene expression Microarray analysis for HEK293 WT and ELL KD with control and 1hr EGF stimulated conditions.

Transcription is a multi-stage process that coordinates several steps within the transcription cycle including chromatin reorganization, RNA polymerase II recruitment, initiation, promoter clearance and elongation. Recent advances have identified the super elongation complex (SEC), containing the eleven nineteen lysine rich leukemia protein (ELL), as a key regulator of transcriptional elongation. We show here that ELL plays a diverse and kinetically distinct role prior to its assembly into the SEC by stabilizing Pol II recruitment/initiation and entry into the pause site. Loss of ELL destabilizes the PIC complexes and results in disruption of early elongation and promoter proximal chromatin structure prior to recruitment of AFF4 and other SEC components. These changes result in significantly reduced transcriptional activation of rapidly induced genes. Thus, ELL plays an early and essential role during rapid high amplitude gene expression that is required for both Pol II pause site entry and release.

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Byun JS, Fufa TD, Wakano C, Fernandez A, Haggerty CM, Sung MH, Gardner K