Regulation of RNA polymerase II activity by CTD phosphorylation and cell cycle control

The carboxyl-terminal domain (CTD) of the largest subunit of mammalian RNA polymerase 11 (RNAP 11) consists of 52 repeats, of a consensus heptapeptide and is subject to phosphorylation and dephosphorylation events during each round of transcription. RNAP 11 activity is regulated during the (ell cycle and cell cycle-dependend changes in RNAP 11 activity correlate well with CTD phosphorylation. In addition, global changes in the CTD phosphorylation status are observed in response to mitogenic or cytostatic signals such as growth factors, mitogens and DNA-damaging agents. Several CTD kinases are members of the cyclin-dependent kinase (CDK) superfamily and associate with transcription initiation complexes. Other CTD kinases implicated in cell cycle regulation include the mitogen-activated protein kinases ERK-1/2 and the c-Abl tyrosine kinase, These observations suggest that reversible RNAP 11 CTD phosphorylation may play a key role in linking cell cycle regulatory events to coordinated changes in transcription. J. Cell. Physiol. 190: 160-169, 2002. (C) 2002 Wile-Liss, Inc.