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リエゾンラボ研究会
発表内容

Title:
HDAC8 mutations in Cornelia de Lange Syndrome provide insight into the cohesin acetylation cycle.

Katsuhiko Shirahige (Ph. D.)
Laboratory of Genome Structure and Function Center for Epigenetic Disease Institute of Molecular and Cellular Biosciences The University of Tokyo

Abstract:
Cornelia de Lange syndrome is a dominantly inherited congenital malformation disorder caused by mutations in the cohesin regulatory protein NIPBL (~60%) and the core cohesin components, SMC1A (~5%) and SMC3 (<1%). Recent work has demonstrated that the ESCO1 acetyltransferase is required for the acetylation of SMC3 to establish cohesiveness of chromatin-loaded cohesin during S-phase. Furthermore, SMC3 is deacetylated during mitosis, suggesting S-phase specificity of SMC3 acetylation in establishing cohesion, as well as the existence of a deacetylase to regulate this activity. Recently yeast HOS1, a class I histone deacetylase, has been reported to deacylate yeast SMC3 during anaphase. To identify a vertebrate SMC3 deactylase, we developed an acetylated SMC3 (SMC3-ac)-specific antibody and performed an RNAi screen of all known vertebrate deacetylases to identify HDAC8 as the likely SMC3 deacetylase. After verification of its function in sister chromatid cohesion and cohesin recycling assays, we screened for mutations in mutation-negative CdLS patients and identified 6 probands with loss-of-function mutations in the X-linked HDAC8 gene. Using an HDAC8-mutated cell line from a male proband, we performed ChIP-Seq of RAD21 and SMC3-ac and noted that there is a dramatic reduction in total cohesin binding. We then demonstrated that HDAC8 is required for efficient recycling of cleaved cohesin from chromosomes in anaphase. Without HDAC8 activity, the cleaved RAD21 N-terminal fragment is not released from SMC3 and the dysfunctional complex remains associated with chromosomes. This work suggests that acetylated SMC3 strongly binds RAD21 and that disruption of its dissociation interferes with stable cohesin reloading during G1. This work demonstrates a central role of HDAC8 as a vertebrate SMC3 deacetylase, refines the mechanism of acetylation in the regulation of cohesin and furthermore, is the first to demonstrate a mechanistic role for a lysine deacetylase in a human developmental disorder.