SUMV-1 antagonizes the activity of synthetic multivulva genes in Caenorhabditis elegans

Ketamine induces apical extracellular matrix modifications in Caenorhabditis elegans

Ketamine is a widely used anesthetic agent since 1960s and has recently been exploited for its rapid antidepressant action at subanesthetic doses. It has been demonstrated that ketamine induces alterations in extracellular matrix (ECM) in rodent models which in part plays a role in its anti-depressant action. The nematode Caenorhabditis elegans serves as a powerful tool for understanding mechanisms of drug action with its short life cycle, genetic amenability and conserved cellular processes. Further investigation is required particularly in in vivo systems to gain broader understanding of ketamine's actions. In this study, we aimed to decipher ketamine-mediated alterations using C. elegans as a model. We show that ketamine specifically induces apical extracellular matrix modifications (aECM) in the vulva and the cuticle. Ketamine treatment phenocopies neuronal migration and vulval invagination defects of chondroitin mutants despite wild-type like chondroitin staining pattern. Normal vulval expansion and defective vulval eversion phenotypes of ketamine-treated animals are suggestive of alterations in the network of aECM factors which do not impinge on chondroitin. Ketamine ameliorates impaired movement of a group of roller mutants characterised with collagen defects in the cuticle and RNA-seq identifies that 30% of the cuticular collagens are upregulated in response to ketamine. Ketamine alters aECM, neuronal migration and collagen expression in C. elegans. We propose C. elegans as a putative animal model to investigate ketamine-mediated ECM modifications.

Physical and functional interaction between SET1/COMPASS complex component CFP-1 and a Sin3S HDAC complex in C. elegans

The CFP1 CXXC zinc finger protein targets the SET1/COMPASS complex to non-methylated CpG rich promoters to implement tri-methylation of histone H3 Lys4 (H3K4me3). Although H3K4me3 is widely associated with gene expression, the effects of CFP1 loss vary, suggesting additional chromatin factors contribute to context dependent effects. Using a proteomics approach, we identified CFP1 associated proteins and an unexpected direct link between Caenorhabditis elegans CFP-1 and an Rpd3/Sin3 small (SIN3S) histone deacetylase complex. Supporting a functional connection, we find that mutants of COMPASS and SIN3 complex components genetically interact and have similar phenotypic defects including misregulation of common genes. CFP-1 directly binds SIN-3 through a region including the conserved PAH1 domain and recruits SIN-3 and the HDA-1/HDAC subunit to H3K4me3 enriched promoters. Our results reveal a novel role for CFP-1 in mediating interaction between SET1/COMPASS and a Sin3S HDAC complex at promoters.

A Network of Chromatin Factors Is Regulating the Transition to Postembryonic Development in Caenorhabditis elegans

Mi2 proteins are evolutionarily conserved, ATP-dependent chromatin remodelers of the CHD family that play key roles in stem cell differentiation and reprogramming. In Caenorhabditis elegans, the let-418 gene encodes one of the two Mi2 homologs, which is part of at least two chromatin complexes, namely the Nucleosome Remodeling and histone Deacetylase (NuRD) complex and the MEC complex, and functions in larval development, vulval morphogenesis, lifespan regulation, and cell fate determination. To explore the mechanisms involved in the action of LET-418/Mi2, we performed a genome-wide RNA interference (RNAi) screen for suppressors of early larval arrest associated with let-418 mutations. We identified 29 suppressor genes, of which 24 encode chromatin regulators, mostly orthologs of proteins present in transcriptional activator complexes. The remaining five genes vary broadly in their predicted functions. All suppressor genes could suppress multiple aspects of the let-418 phenotype, including developmental arrest and ectopic expression of germline genes in the soma. Analysis of available transcriptomic data and quantitative PCR revealed that LET-418 and the suppressors of early larval arrest are regulating common target genes. These suppressors might represent direct competitors of LET-418 complexes for chromatin regulation of crucial genes involved in the transition to postembryonic development.

Evidence of a MOF histone acetyltransferase-containing NSL complex in C. elegans

Regulation of chromatin is a key process in the developmental control of gene expression. Many multi-subunit protein complexes have been found to regulate chromatin through the modification of histone residues. One such complex is the MOF histone acetyltransferase-containing NSL complex. While the composition of the human and Drosophila NSL complexes has been determined and the functions of these complexes investigated, the existence of an equivalent complex in nematodes such as Caenorhabditis elegans has not yet been explored. Here we summarise evidence, from our own work and that of others, that homologues of NSL complex components are found in C. elegans. We review data suggesting that nematode proteins SUMV-1 and SUMV-2 are homologous to NSL2 and NSL3, respectively, and that SUMV-1 and SUMV-2 may form a complex with MYS-2, the worm homolog of MOF. We propose that these interactions suggest the existence of a nematode NSL-like complex and discuss the roles of this putative NSL complex in worms as well as exploring the possibility of crosstalk between NSL and COMPASS complexes via components that are common to both. We present the groundwork from which a full characterization of a nematode NSL complex may begin.