De novo mutations of MSL3 cause a novel X-linked syndrome due to impaired histone H4 lysine 16 acetylation

ABSTRACT: Epigenetic regulation by histone acetylation plays a key role in cellular homeostasis and its misregulation is associated with human disease. The Male Specific Lethal (MSL) complex associated MOF/KAT8 histone acetyl-transferase is responsible for bulk Histone 4 Lysine 16 acetylation (H4K16ac) in flies and mammals. H4K16ac is a peculiar case amongst the many histone tail modifications in directly affecting higher order chromatin compaction. Yet, its importance during human development and a potential involvement in human pathologies remains largely unknown. Here, we uncover that pathogenic variants in MSL3, a component of the MSL complex, are causative for a new recognizable X-linked syndrome affecting both male and female individuals. Common clinical features of the syndrome include a global delay in developmental milestones and speech, a progressive gait disturbance and recognizable dysmorphism. Using skin biopsies and patient-derived primary fibroblasts, we demonstrate that de novo variants or deletions of MSL3 affect the assembly and enzymatic activity of the MSL complex, hence globally impacting H4K16ac levels in vivo. Transcriptome analysis from patient cells showed misregulation of cellular pathways involved in morphogenesis, cellular shape and cell migration. Using RNAi and MSL3 reintroduction experiments, we phenocopy acute responses occurring on H4K16ac-sensitive MSL target genes, supporting that this syndrome is caused by the loss of MSL3. Finally, we use HDAC inhibitors to rebalance acetylation levels and are able to alleviate both molecular and cellular phenotypes of MSL3 patients cells. Taken together, we characterize a novel syndrome, which is caused by mutations of an epigenetic regulator, allowing us for the first time to unravel the crucial role of H4K16ac during human development.

ORGANISM(S): Homo sapiens

PROVIDER: GSE102250 | GEO | 2018/08/06

REPOSITORIES: GEO