HDAC8 mutations in Cornelia de Lange syndrome affect the cohesin acetylation cycle

Abstract

Cornelia de Lange syndrome (CdLS) is a dominantly inherited congenital malformation disorder caused by mutations in the cohesin-loading protein NIPBL1,2 for nearly 60% of individuals with classical CdLS3-5 and in the core cohesin components SMC1A (~5%) and SMC3 (<1%) for a smaller fraction of probands6,7. In humans, the multi-subunit complex cohesin is comprised of SMC1, SMC3, RAD21 and a STAG protein to form a ring structure proposed to encircle sister chromatids to mediate sister chromatid cohesion (SCC)8 as well as play key roles in gene regulation9. SMC3 is acetylated during S-phase to establish cohesiveness of chromatin-loaded cohesin10-13 and in yeast, HOS1, a class I histone deacetylase, deacetylates SMC3 during anaphase14-16. Here we report the identification of HDAC8 as the vertebrate SMC3 deacetylase as well as loss-of-function HDAC8 mutations in six CdLS probands. Loss of HDAC8 activity results in increased SMC3 acetylation (SMC3-ac) and inefficient dissolution of the “used” cohesin complex released from chromatin in both prophase and anaphase. While SMC3 with retained acetylation is loaded onto chromatin, ChIP-Seq analysis demonstrates decreased occupancy of cohesin localization sites that results in a consistent pattern of altered transcription seen in CdLS cell lines with either NIPBL or HDAC8 mutations.

Chromosome Dynamics during Mitosis

“…A series of subsequent studies showed that two conserved residues in SMC3 are the essential targets of the Eco1/ESCO1 acetyltransferase, and the acetylation reactions are indeed essential for cohesion establishment in budding yeast (Ben-Shahar et al 2008;Unal et al 2008) and humans (Zhang et al 2008). More recently, the deacetylase that reverses this reaction has been identified as Hos1 in budding yeast (Beckouët et al 2010;Borges et al 2010;Xiong et al 2010) and HDAC8 in humans (Deardorff et al 2012). It has been proposed that the deacetylation reaction plays an important role in "recycling" used cohesin complexes for the next cell cycle.…”

“…It has been proposed that the deacetylation reaction plays an important role in "recycling" used cohesin complexes for the next cell cycle. It is also important to note that deficiencies in this acetylation/deacetylation cycle of cohesin cause developmental diseases in humans, such as Roberts syndrome (Vega et al 2005) and Cornelia de Lange syndrome (Deardorff et al 2012).…”

HDAC8 Inhibition Blocks SMC3 Deacetylation and Delays Cell Cycle Progression without Affecting Cohesin-dependent Transcription in MCF7 Cancer Cells

“…The SMC3 subunit is acetylated on Lys-105 and Lys-106 by ESCO1/2 during S phase, and acetylation is reversed by the Class I HDAC, HDAC8, at telophase (22)(23)(24)(25). Deacetylation of SMC3 is crucial for recycling of cohesin for use in subsequent cell cycles (22,24,26).…”

“…Deacetylation of SMC3 is crucial for recycling of cohesin for use in subsequent cell cycles (22,24,26). Deardorff et al (25) showed that mutation or depletion of HDAC8 led to the accumulation of ac-SMC3, reduced chromatin-bound cohesin, and resulted in genome-wide cohesin-mediated transcriptional dysregulation. Depletion of HDAC8 affected transcriptional regulation in HeLa cells without markedly disrupting cycling of these cells.…”

Screen for reactivation of MeCP2 on the inactive X chromosome identifies the BMP/TGF-β superfamily as a regulator of XIST expression

“…However, the resulting disease state could potentially be ameliorated by reactivation of the wildtype allele on the inactive X chromosome (Xi). Several neurodevelopmental disorders in females are caused by heterozygous mutations of X-linked genes including MeCP2 (3), DDX3X (4), KIAA2022 (5), USP9X (6), CDKL5 (7), HDAC8 (8), and SMC1A (9). Rett syndrome, one of the most common hereditary forms of severe cognitive impairment in girls, is caused by a heterozygous mutation in the MeCP2 gene (3), which encodes a methyl-DNA-binding protein essential for normal development and function of the neurons (10).…”