文摘
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Summary
¦Á-catenin is central to recruitment of actin networks to the cadherin-catenin complex [], but how such networks are subsequently stabilized against stress applied during morphogenesis is poorly understood. To identify proteins that functionally interact with ¦Á-catenin in this process, we performed enhancer screening using a weak allele of the C.?elegans ¦Á-catenin, hmp-1, thereby identifying UNC-94/tropomodulin. Tropomodulins (Tmods) cap the minus ends of F-actin in sarcomeres []. They also regulate lamellipodia [], can promote actin nucleation [], and are required for normal cardiovascular development [] and neuronal growth-cone morphology []. Tmods regulate the morphology of cultured epithelial cells [], but their role in epithelia in?vivo remains unexplored. We find that UNC-94 is?enriched within a HMP-1-dependent junctional-actin network at epidermal adherens junctions subject to stress during morphogenesis. Loss of UNC-94 leads to discontinuity of this network, and high-speed filming of hmp-1(fe4);unc-94(RNAi) embryos reveals large junctional displacements that depend on the Rho pathway. In?vitro, UNC-94 acts in combination with HMP-1, leading to longer actin bundles than with HMP-1 alone. Our data suggest that Tmods protect actin filaments recruited by ¦Á-catenin from minus-end subunit loss, enabling them to withstand the stresses of morphogenesis.
