The 7SK snRNP associates with the little elongation complex to promote snRNA gene expression

The 7 SK small nuclear RNP (sn RNP ), composed of the 7 SK small nuclear RNA (sn RNA ), Me PCE , and Larp7, regulates the mRNA elongation capacity of RNA polymerase II ( RNAPII ) through controlling the nuclear activity of positive transcription elongation factor b (P‐ TEF b). Here, we demonstrate that the human 7 SK sn RNP also functions as a canonical transcription factor that, in collaboration with the little elongation complex ( LEC ) comprising ELL , Ice1, Ice2, and ZC 3H8, promotes transcription of RNAPII ‐specific spliceosomal sn RNA and small nucleolar RNA (sno RNA ) genes. The 7 SK sn RNA specifically associates with a fraction of RNAPII hyperphosphorylated at Ser5 and Ser7, which is a hallmark of RNAPII engaged in sn RNA synthesis. Chromatin immunoprecipitation (Ch IP ) and chromatin isolation by RNA purification (Ch IRP ) experiments revealed enrichments for all components of the 7 SK sn RNP on RNAPII ‐specific sn/sno RNA genes. Depletion of 7 SK sn RNA or Larp7 disrupts LEC integrity, inhibits RNAPII recruitment to RNAPII ‐specific sn/sno RNA genes, and reduces nascent sn RNA and sno RNA synthesis. Thus, through controlling both mRNA elongation and sn/sno RNA synthesis, the 7 SK sn RNP is a key regulator of nuclear RNA production by RNAPII.