Histone H2B monoubiquitination regulates heart development via epigenetic control of cilia motility

Abstract

Genomic analyses of patients with congenital heart disease (CHD) have identified significant contribution from mutations affecting cilia genes and chromatin remodeling genes; however, the mechanism(s) connecting chromatin remodeling to CHD is unknown. Histone H2B monoubiquitination (H2Bub1) is catalyzed by the RNF20 complex consisting of RNF20, RNF40, and UBE2B. Here, we show significant enrichment of loss-of-function mutations affecting H2Bub1 in CHD patients (enrichment 6.01,P= 1.67 × 10−03), some of whom had abnormal laterality associated with ciliary dysfunction. InXenopus, knockdown ofrnf20andrnf40results in abnormal heart looping, defective development of left–right (LR) asymmetry, and impaired cilia motility. Rnf20, Rnf40, and Ube2b affect LR patterning and cilia synergistically. Examination of global H2Bub1 level inXenopusembryos shows that H2Bub1 is developmentally regulated and requires Rnf20. To examine gene-specific H2Bub1, we performed ChIP-seq of mouse ciliated and nonciliated tissues and showed tissue-specific H2Bub1 marks significantly enriched at cilia genes including the transcription factorRfx3. Rnf20 knockdown results in decreased levels ofrfx3mRNA inXenopus, and exogenousrfx3can rescue the Rnf20 depletion phenotype. These data suggest that Rnf20 functions at theRfx3locus regulating cilia motility and cardiac situs and identify H2Bub1 as an upstream transcriptional regulator controlling tissue-specific expression of cilia genes. Our findings mechanistically link the two functional gene ontologies that have been implicated in human CHD: chromatin remodeling and cilia function.

Egr2-guided histone H2B monoubiquitination is required for peripheral nervous system myelination

“…We here show that SC-specific deletion of Rnf40 and the resulting loss of H2Bub1 led to severe hypomyelination that secondarily triggers an inflammatory response and a progressive loss of axons and thereby interfered with peripheral nerve function. Apart from a study on the heart where Rnf40 and H2Bub1 impact development via epigenetic control of cilia motility ( 45 ), this is to our knowledge the only study where the role of H2B monoubiquitination and the responsible E3 ligase has been investigated during ontogenetic development. We also like to point out that apart from studies on histone deacetylases ( 46 , 47 ), very few data exist on the role of specific histone modifications in SCs.…”

In vivo CRISPR screening identifies RNF20/40 as epigenetic regulators of cardiomyocyte maturation

“…Mutations in pathways that regulate H2Bub1, including Rnf20 and Rnf40, have been reported in humans with congenital heart defects (CHD) 32,33 and were recently reported to influence cardiac looping via regulation of motile cilia during early embryonic development 32 . Our results extend the function of Rnf20/40 into the postnatal heart, suggesting that mutations in these genes could both cause a structural heart defect and contribute to cardiac dysfunction after surgical repair.…”

“…These genes are E3 ubiquitin ligases that together form a complex that monoubiquitinates histone 2B at lysine 120 (H2Bub1) 30,31 . Human genetic studies have implicated de novo Rnf20/Rnf40 mutations in congenital heart disease 32,33 . The postnatal cardiac functions of these genes have not been studied.…”

Phosphorylation Modifications Regulating Cardiac Protein Quality Control Mechanisms

“…Knocking down CDK9 reduced UBE2A phosphorylation, which then decreased monoubiquitination of histone H2B and PCNA, suggesting phosphorylation at serine 120 activates UBE2A (Shchebet et al, 2012). This finding is of particular interest to the heart, as a recent study identified monoubiquitination of H2B is a transcriptional regulator that controls expression of cilia genes, where mutations have been implicated in congenital heart disease (Robson et al, 2019). ER stress occurs in various cardiovascular diseases with impaired proteostasis (Ochoa et al, 2018).…”