A long non-coding RNA is required for targeting centromeric protein A to the human centromere.

Delphine Quénet,Yamini Dalal

doi:10.7554/elife.03254

Abstract

The centromere is a specialized chromatin region marked by the histone H3 variant CENP-A. Although active centromeric transcription has been documented for over a decade, the role of centromeric transcription or transcripts has been elusive. Here, we report that centromeric α-satellite transcription is dependent on RNA Polymerase II and occurs at late mitosis into early G1, concurrent with the timing of new CENP-A assembly. Inhibition of RNA Polymerase II-dependent transcription abrogates the recruitment of CENP-A and its chaperone HJURP to native human centromeres. Biochemical characterization of CENP-A associated RNAs reveals a 1.3 kb molecule that originates from centromeres, which physically interacts with the soluble pre-assembly HJURP/CENP-A complex in vivo, and whose down-regulation leads to the loss of CENP-A and HJURP at centromeres. This study describes a novel function for human centromeric long non-coding RNAs in the recruitment of HJURP and CENP-A, implicating RNA-based chaperone targeting in histone variant assembly.

Highlights

Specialized chromatin domains called centromeres play an essential role in chromosome segregation, serving as a platform for kinetochore complex formation, which in turn binds spindle microtubules at mitosis (Verdaasdonk and Bloom, 2011)
Using chromatin immunoprecipitation (IP), and immunofluorescence (IF) on chromatin fibers, we find that RNA Polymerase II (RNAPII), in conjunction with TATA-box binding protein (TBP) localizes to, and actively transcribes native human centromeres from late mitosis to early G1
Centromeric transcription has been previously described in human cells, and RNAPII has been implicated in this process (Saffery et al, 2003; Wong et al, 2007; Bergmann et al, 2011; Chan et al, 2012)

Summary

Introduction

Specialized chromatin domains called centromeres play an essential role in chromosome segregation, serving as a platform for kinetochore complex formation, which in turn binds spindle microtubules at mitosis (Verdaasdonk and Bloom, 2011). Centromeric chromatin has long been considered heterochromatic, despite exhibiting a bivalent organization with heterochromatin-like post-translational modifications (PTMs), such as H3 and H4 hypo-acetylation, and transcription-coupled PTMs, including dimethylation on H3 lysine 4 (H3K4me2) (Sullivan and Karpen, 2004; Heintzman et al, 2007; Zhou et al, 2011). The function of such bivalent modifications has remained mysterious. The exact timing of centromeric transcription, the polymerase involved, the identity of centromeric RNAs and their precise role in maintaining native centromere integrity in human cells has been elusive

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