Pin1 modulates the structure and function of human RNA polymerase II.
The C-terminal domain of the RNA polymerase (RNAP) II largest subunit (CTD) plays critical roles both in transcription of mRNA precursors and in the processing reactions needed to form mature mRNAs. The CTD undergoes dynamic changes in phosphorylation during the transcription cycle, and this plays a significant role in coordinating its multiple activities. But how these changes themselves are regulated is not well understood. Here we show that the peptidyl-prolyl isomerase Pin1 influences the phosphorylation status of the CTD in vitro by inhibiting the CTD phosphatase FCP1 and stimulating CTD phosphorylation by cdc2/cyclin B. This is reflected in vivo by accumulation of hypophosphorylated RNAP II in pin1-/- cells, and of a novel hyper-hyperphosphorylated form in cells induced to overexpress Pin1. This hyper-hyperphosphorylated form of RNAP II also accumulates in M-phase cells, in a Pin1-dependent manner, and associates specifically with Pin1. Functionally, we find that Pin1 overexpression specifically inhibits ongoing transcription of mRNA precursors in vivo and both transcription and RNAP II-stimulated pre-mRNA splicing in cell extracts. Pin1 thus plays a significant role in regulating RNAP II CTD structure and function.
Department of Biological Sciences, Columbia University, New York, New York 10027, USA.
Yu-Xin
YX
Xu
Yutaka
Y
Hirose
Xiao Zhen
XZ
Zhou
Kun Ping
KP
Lu
James L
JL
Manley
D000818:Animals; D019926:Cyclin B / Q000378:metabolism; D005347:Fibroblasts / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D051379:Mice; D008938:Mitosis / Q000235:genetics; D041681:NIH 3T3 Cells; D000072340:NIMA-Interacting Peptidylprolyl Isomerase; D019696:Peptidylprolyl Isomerase / Q000502:physiology*; D010749:Phosphoprotein Phosphatases / Q000378:metabolism*; D010766:Phosphorylation; D011233:Precipitin Tests; D012319:RNA Polymerase II / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D012322:RNA Precursors / Q000235:genetics / Q000378:metabolism; D012326:RNA Splicing; D017381:Spliceosomes; D014158:Transcription, Genetic
D019926:Cyclin B; D000072340:NIMA-Interacting Peptidylprolyl Isomerase; D012322:RNA Precursors; D012319:RNA Polymerase II; D010749:Phosphoprotein Phosphatases; C116022:carboxy-terminal domain phosphatase; C000606846:PIN1 protein, human; D019696:Peptidylprolyl Isomerase; C000606850:Pin1 protein, mouse