CHD8 Associates with Human Staf and Contributes to Efficient U6 RNA Polymerase III Transcription

Abstract

Chromatin remodeling and histone modification are essential for eukaryotic transcription regulation, but little is known about chromatin-modifying activities acting on RNA polymerase III (Pol III)-transcribed genes. The human U6 small nuclear RNA promoter, located 5′ of the transcription start site, consists of a core region directing basal transcription and an activating region that recruits the transcription factors Oct-1 and Staf (ZNF143). Oct-1 activates transcription in part by helping recruit core binding factors, but nothing is known about the mechanisms of transcription activation by Staf. We show that Staf activates U6 transcription from a preassembled chromatin template in vitro and associates with several proteins linked to chromatin modification, among them chromodomain-helicase-DNA binding protein 8 (CHD8). CHD8 binds to histone H3 di- and trimethylated on lysine 4. It resides on the human U6 promoter as well as the mRNA IRF3 promoter in vivo and contributes to efficient transcription from both these promoters. Thus, Pol III transcription from type 3 promoters uses some of the same factors used for chromatin remodeling at Pol II promoters.

We thank Jaime H. Reina, who constructed the U6 reporter cell line; Jacek Skowronski for the GST-Nef construct; Arne Stenlund for discussion and help with many of the experiments and for hosting C.-C.Y. in his laboratory; Daniel Bogenhagen, Janet Leatherwood, and Rui-Ming Xu for advice and discussion; and Yu-Hui Chen for help with statistical analysis.

This work was funded by the Howard Hughes Medical Institute, by NIH grant GM38810, and by SNSF grant 3100A0-109941/1.