pix-1 Controls Early Elongation in Parallel with mel-11 and let-502 in Caenorhabditis elegansReport as inadecuate




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Cell shape changes are crucial for metazoan development. During Caenorhabditis elegans embryogenesis, epidermal cell shape changes transform ovoid embryos into vermiform larvae. This process is divided into two phases: early and late elongation. Early elongation involves the contraction of filamentous actin bundles by phosphorylated non-muscle myosin in a subset of epidermal hypodermal cells. The genes controlling early elongation are associated with two parallel pathways. The first one involves the rho-1-RHOA-specific effector let-502-Rho-kinase and mel-11-myosin phosphatase regulatory subunit. The second pathway involves the CDC42-RAC-specific effector pak-1. Late elongation is driven by mechanotransduction in ventral and dorsal hypodermal cells in response to body-wall muscle contractions, and involves the CDC42-RAC-specific Guanine-nucleotide Exchange Factor GEF pix-1, the GTPase ced-10-RAC and pak-1.In this study, pix-1 is shown to control early elongation in parallel with let-502-mel-11, as previously shown for pak-1. We show that pix-1, pak-1 and let-502 control the rate of elongation, and the antero-posterior morphology of the embryos. In particular, pix-1 and pak-1 are shown to control head, but not tail width, while let-502 controls both head and tail width. This suggests that let-502 function is required throughout the antero-posterior axis of the embryo during early elongation, while pix-1-pak-1 function may be mostly required in the anterior part of the embryo. Supporting this hypothesis we show that low pix-1 expression level in the dorsal-posterior hypodermal cells is required to ensure high elongation rate during early elongation.



Author: Emmanuel Martin , Sharon Harel , Bernard Nkengfac, Karim Hamiche, Mathieu Neault, Sarah Jenna

Source: http://plos.srce.hr/



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