During development, tissues are often subjected to internal and external mechanical stresses. Morphogenesis of the C. elegans embryo involves important cell shape changes, which rely on a remodelling of the epidermal cytoskeletal networks. We have previously shown that mutations in the C. elegans plakin locus
vab-10 strongly affect embryonic elongation.
vab-10 encodes several large isoforms (>3000 a.a.) with potential actin-, intermediate filament- and microtubule- binding domains. VAB-10A, the plectin homologue, is a major component of fibrous organelles and is required to maintain attachment of epidermal cells to the ECM when muscle contracts. VAB-10B, the MACF homologue, links the basal and apical epidermal plasma membranes, and is required to protect epidermal cells against mechanical rupture during elongation. Given the huge size and the multiple protein interacting domains of VAB-10, these cytolinker proteins could remodel the cytoskeleton by acting together with several partners. To identify VAB-10 partners we are using genome-wide enhancer screen by RNAi. We feed a weak and viable
vab-10A allele (
e698), with bacterial clones expressing dsRNA, and look for enhancement of the phenotype in this mutant backgroud but not in WT. We have so far examined genes corresponding to the chromosomes I, II, III, IV and X, and identified 14 potential candidates encoding different classes of proteins (DNA or RNA binding proteins, cytoskeletal proteins, protein kinase, ubiquitine ligase). These candidates comprise three already known proteins to act in the same pathway as
vab-10 (
vab-19,
unc-52 and
mec-8). The embryonic and larval phenotypes observed resemble
vab-10 severe phenotypes with elongation defects and muscle or cuticle detachment. We will present our analysis of the expression pattern of the candidates genes, and the results of immunostainings with VAB-10 and musle specific antibodies after RNAi injection.