Control of RNA Polymerase II Elongation Potential by a Novel Carboxyl-terminal Domain Kinase

Abstract

The entry of RNA polymerase II into a productive mode of elongation is controlled, in part, by the postinitiation activity of positive transcription elongation factor b (P-TEFb) (Marshall, N. F., and Price, D. H. (1995) J. Biol. Chem. 270, 12335-12338). We report here that removal of the carboxyl-terminal domain (CTD) of the large subunit of RNA polymerase II abolishes productive elongation. Correspondingly, we found that P-TEFb can phosphorylate the CTD of pure RNA polymerase II. Furthermore, P-TEFb can phosphorylate the CTD of RNA polymerase II when the polymerase is in an early elongation complex. Both the function and kinase activity of P-TEFb are blocked by the drugs 5, 6-dichloro-1-beta-D-ribofuranosylbenzimidazole (DRB) and H-8. P-TEFb is distinct from transcription factor IIH (TFIIH) because the two factors have no subunits in common, P-TEFb is more sensitive to DRB than is TFIIH, and most importantly, TFIIH cannot substitute functionally for P-TEFb. We propose that phosphorylation of the CTD by P-TEFb controls the transition from abortive into productive elongation mode.

Cyclin T2: A novel miR‐15a target gene involved in early spermatogenesis

“…Our findings demonstrated that miR-15a decreased continuously before meiosis and probably contributed to the on-going process of spermatogenesis, which is similar to the effect observed with macrophage differentiation [36]. P-TEFb is thought to facilitate the transition from abortive to productive elongation catalytically by phosphorylating the carboxyl-terminal domain (CTD) of RNA polymerase II [37]. Genetic analysis has implicated a broad requirement for the CDK9/cyclin T complex in Caenorhabditis elegans during early embryonic gene expression [38].…”

Single Cell Analysis Reveals Concomitant Transcription of Pluripotent and Lineage Markers During the Early Steps of Differentiation of Embryonic Stem Cells

“…As a result of the accumulation of nascent transcripts, presumably through the concomitant activity of multiple RNA polymerases II and the existence of rate-limiting processing steps, the nuclear RNA FISH signals are usually much more intense than the cytoplasmic ones. To ascertain that the intense nuclear dots that I observed corresponded to sites of nascent transcription, differentiating cells were treated for 30 minutes with 50 mM 5,6-dichlorobenzimidazole 1-b-D-ribofuranoside (DRB), a CDK9 inhibitor that blocks the elongating activity of RNA polymerase II [39]. Treatment with this transcriptional inhibitor led to a 10-fold decrease in the proportion of cells that displayed nuclear RNA FISH signals, thereby confirming their identity as sites of nascent transcription (Supporting Information Fig.…”

Cyclin T: Three forms for different roles in physiological and pathological functions

“…The post-initiation processivity of RNA pol II is controlled by both negative and positive factors (Marshall et al, 1996;Reines et al, 1996;Yamaguchi et al, 1998). Negative factors (N-TEF), such as factor 2 , 1998 and DRB-sensitivity inducing factor (DSIF) Wada et al, 1998), cause premature stopping and termination of initiated polymerase resulting in the generation of only short abortive transcript.…”

“…Positive factors (P-TEF) enable RNA pol II to overcome the promoter proximal pausing and premature termination and to enter productive elongation Price, 1992, 1995). P-TEFb is proposed to facilitate the transition from abortive to productive elongation by phosphorylating the CTD of the largest subunit of RNA pol II (Marshall et al, 1996;Peng et al, 1998b). Various kinases and phosphatases control the CTD phosphorylation during different transcription stages (Dahmus, 1994(Dahmus, , 1995.…”

“…Various kinases and phosphatases control the CTD phosphorylation during different transcription stages (Dahmus, 1994(Dahmus, , 1995. While in preinitiation complexes (Laybourn and Dahmus, 1989) and in early elongation complex in vitro (Marshall et al, 1996), RNA pol II results to be hypophosphorylated, during productive elongation it is hyperphosphorylated (Laybourn and Dahmus, 1989;O'Brien et al, 1994). P-TEFb is required for transcription elongation of many genes Price, 1992, 1995).…”