DamID: Loss of a heterochromatin anchor rescues altered genome organization and EDMD muscle defects triggered by a laminopathy mutation

Point mutations in nuclear structural protein laminA produce rare and generally tissue-specific diseases called laminopathies. The introduction of a human Emery Dreifuss Muscular Dystrophy (EDMD)-inducing mutation (laminA-Y45C) into C. elegans lamin (LMN-Y59C), recapitulates many EDMD phenotypes, and results in hyper-sequestration of heterochromatic arrays at the nuclear periphery. Using muscle-specific Emerin Dam-ID we show that the LMN-Y59C mutation also leads to misorganization of endogenous chromatin. We find increased perinuclear anchoring primarily along chromosome arms, and enhanced release of chromosomal cores. Coincidentally, Y59C worms have reduced locomotion and compromised sarcomere integrity. By coupling this mutation with deletion of the perinuclear chromodomain protein CEC-4, which tethers H3K9-methylated chromatin, we rescue the EDMD-like physiology and ultrastructural defects in sarcomeres. It further counteracts the altered spatial organization of chromosomal sequences, particularly along chromosomal arms. The data in this submission refer to the identification of chromatin enriched at the nuclear periphery (as measured by interaction with Dam::EMR-1) in muscle cells of L3/L4 control animals or cec-4 mutants expressing either GFP::LMN-1 (wild type lamin) or GFP::LMN-1(Y59C). Comparison of Dam::EMR-1 DNA association in wild type and cec-4(ok3124) mutants expressing either GFP::LMN-1 or GFP::LMN-1(Y59C). Strains expressing a nuclear GFP::Dam fusion were used to normalise for changes in chromatin accessibility. Using a myo-3p::FLP driver to induce genome recombination (Muñoz-Jiménez et al, PMID: 28646043), the Dam fusion proteins were expressed uniquely in intestine. Three biological replicas were prepared: all strains were grown in parallel in each replica.