title: Human SCP4 is a chromatin-associated CTD phosphatase and exhibits the dynamic translocation during erythroid differentiation.
abstract: The C-terminal domain (CTD) of the RNA polymerase II (Pol II) large subunit contains tandem repeats of the heptapeptide, Tyr1-Ser2-Pro3-Thr4-Ser5-Pro6-Ser7. The CTD is subject to dynamic phosphorylation during transcription, mainly at serine residues (Ser2, Ser5 and Ser7). Regulation of CTD phosphorylation by specific kinases and phosphatases is crucial for coordinating transcription with RNA processing and histone modification. Human small CTD phosphatase 4 (SCP4), also called CTDSPL2 or HSPC129, is a putative CTD phosphatase belonging to the FCP/SCP family and implicated in control of ε- and γ-globin gene expression. Here, we report the biochemical and functional characterization of SCP4. SCP4 exhibited Ser5-preferential CTD phosphatase activity in vitro, while small interfering RNA-mediated SCP4 knockdown in HeLa cells increased phosphorylation levels of Pol II at Ser5 and Ser7, but not at Ser2. Furthermore, cell fractionation, chromatin immunoprecipitation and immunofluorescence assays revealed an exclusive localization for SCP4 in the chromatin, particularly at transcriptionally silenced chromosomal regions. Interestingly, SCP4 was gradually released from the chromatin fraction during hemin-induced erythroid differentiation of K562 cells, with concomitant cytoplasmic accumulation. Therefore, SCP4 is a unique chromatin-associated, Ser5-preferential CTD phosphatase that preferentially distributes to transcriptionally silenced gene regions and may participate in gene regulation during erythroid differentiation.
authors.affiliation: Laboratory of Gene Regulation, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, 2630 Sugitani, Toyama 930-0194, Japan and.
authors.forename: Shotaro
authors.initials: S
authors.lastname: Wani
authors.affiliation: Laboratory of Gene Regulation, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, 2630 Sugitani, Toyama 930-0194, Japan and.
authors.forename: Ai
authors.initials: A
authors.lastname: Sugita
authors.affiliation: Laboratory of Gene Regulation, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, 2630 Sugitani, Toyama 930-0194, Japan and Department of Biochemistry, Nagasaki University School of Medicine, 1-12-4 Sakamoto, Nagasaki 852-8523, Japan.
authors.forename: Yoshiaki
authors.initials: Y
authors.lastname: Ohkuma
authors.affiliation: Laboratory of Gene Regulation, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, 2630 Sugitani, Toyama 930-0194, Japan and yh620@pha.u-toyama.ac.jp.
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Hirose
mesh_terms: D002454:Cell Differentiation / Q000502:physiology*; D002843:Chromatin / Q000201:enzymology* / Q000235:genetics; D041905:Erythroid Cells / Q000166:cytology / Q000201:enzymology*; D006367:HeLa Cells; D006801:Humans; D020014:K562 Cells; D010749:Phosphoprotein Phosphatases / Q000235:genetics / Q000378:metabolism*; D021381:Protein Transport / Q000502:physiology
chemical_list: D002843:Chromatin; C556670:CTDSPL2 protein, human; D010749:Phosphoprotein Phosphatases
keywords: CTD phosphatase; SCP4; chromatin regulation; erythroid differentiation; gene silencing