THE HARDIN LABMECHANISMS of MORPHOGENESIS
Supplemental material for the following paper:
Lynch, A.M.*, Zhu, Y.*, Lucas, B.G., Winkelman, J.D., Bai, K., Martin, S.C.T. , Samuel Block, S., Slabodnick, M.S., Audhya, A., Goldstein, B., Pettitt, J., Gardel, M.L., and Hardin, J.(2022). TES-1/Tes and ZYX-1/Zyxin protect junctional actin networks under tension during epidermal morphogenesis in the C. elegans embryo. Curr. Biol., https://doi.org/10.1016/j.cub.2022.10.045 (*= co-first authors). PubMed
Summary
LIM-domain-containing repeat (LCR) proteins are recruited to strained actin filaments within stress fibers in cultured cells,1,2,3 but their roles at cell-cell junctions in living organisms have not been extensively studied. Here, we show that the Caenorhabditis elegans LCR proteins TES-1/Tes and ZYX-1/Zyxin are recruited to apical junctions during embryonic elongation when junctions are under tension. In genetic backgrounds in which embryonic elongation fails, junctional recruitment is severely compromised. The two proteins display complementary patterns of expression: TES-1 is expressed in lateral (seam) epidermal cells, whereas ZYX-1 is expressed in dorsal and ventral epidermal cells. tes-1 and zyx-1 mutant embryos display junctional F-actin defects. The loss of either protein strongly enhances morphogenetic defects in hypomorphic mutant backgrounds for cadherin/catenin complex (CCC) components. The LCR regions of TES-1 and ZYX-1 are recruited to stress fiber strain sites (SFSSs) in cultured vertebrate cells. Together, these data establish TES-1 and ZYX-1 as components of a multicellular, tension-sensitive system that stabilizes the junctional actin cytoskeleton during embryonic morphogenesis.
Video S1. tes-1(RNAi) enhances the severity of morphogenetic defects in hmp-1(fe4) embryos, related to Figure 1. Time lapse movie comparing hmp-1(fe4) homozygous and hmp-1(fe4); tes-1(RNAi) embryos. The latter fail consistently during early elongation, and all develop the Humpback phenotype. Time is shown in hours:minutes.
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Video S2. Laser-induced recruitment of the ZYX-1 LCR::mCherry and mouse GFP::Zyxin to SFSS, related to Figure 4. Time lapse movie showing laser induction of a stress fiber strain site (SFSS) in a representative zyxin -/- mouse embryo fibroblast (MEF) rescued with stably integrated M. musculus GFP-zyxin and transiently transfected with a construct encoding ZYX-1 LCR::mCherry related to Figure 4D. White boxes show where light was targeted, and white arrows denote developing SFSS. Time is shown in minutes:sec.
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Video S3. Laser-induced recruitment of the TES-1 LCR::mCherry and mouse GFP::Zyxin to SFSS, related to Figure 4. Time-lapse movie showing laser induction of a stress fiber strain site (SFSS) in a representative zyxin -/- mouse embryo fibroblast (MEF) rescued with stably integrated M. musculus GFP-zyxin and transiently transfected with a construct encoding TES-1 LCR::mCherry related to Figure 4F. White boxes show where light was targeted, and white arrows denote developing SFSS. Time is shown in minutes:sec.
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