RPB7/CTDP1 stabilizes and licenses Pol II termination to reinitiation [RNA-Seq]

The regulations of transcription process have been extensively investigated, but how RNA Pol II terminates and reinitiates a new round of transcription remains elusive. Here, we found that RPB7 loss triggers the degradation of RNA Pol II. RPB7 degradation combing knock out of E3 ligase Cullin 3 led to the accumulation of phosphorylated Pol II in the soluble fractions and Pol II reinitiation failure. The stability of recycled Pol II is dependent on the loop-region and dimerization of RPB7 and the phosphorylation state of Pol II CTD. Site-specific cancer mutations in the RPB7 loop-region caused the dysregulations of specific gene expression. Moreover, the loss of RPB7 or CTD phosphatase subunit 1 (CTDP1) result in the defects in Pol II termination-reinitiation recycle. Together, our study demonstrates that RPB7/CTDP1 controls the dephosphorylation and stabilization of RNA Pol II to permit RNA Pol II termination to reinitiation recycle in mammalian cells.