Non-junctional E-Cadherin Clusters Regulate the Actomyosin Cortex in the C. elegans Zygote

Anup Padmanabhan, Hui Ting Ong, Ronen Zaidel-Bar*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

Classical cadherins are well known for their essential function in mediating cell-cell adhesion via their extra-cellular cadherin domains and intra-cellular connections to the actin cytoskeleton [1–3]. There is evidence, however, of adhesion-independent cadherin clusters existing outside of cell-cell junctions [4–6]. What function, if any, these clusters have is not known. HMR-1, the sole classical cadherin in Caenorhabditis elegans, plays essential roles during gastrulation, blastomere polarity establishment, and epidermal morphogenesis [7–11]. To elucidate the physiological roles of non-junctional cadherin, we analyzed HMR-1 in the C. elegans zygote, which is devoid of neighbors. We show that non-junctional clusters of HMR-1 form during the one-cell polarization stage and associate with F-actin at the cortex during episodes of cortical flow. Non-junctional HMR-1 clusters downregulate RHO-1 activity and inhibit accumulation of non-muscle myosin II (NMY-2) at the anterior cortex. We found that HMR-1 clusters impede cortical flows and play a role in preserving the integrity of the actomyosin cortex, preventing it from splitting in two. Importantly, we uncovered an inverse relationship between the amount of HMR-1 at the cell surface and the rate of cytokinesis. The effect of HMR-1 clusters on cytokinesis is independent of their effect on NMY-2 levels, and is also independent of their extra-cellular domains. Thus, in addition to their canonical role in inter-cellular adhesion, HMR-1 clusters regulate RHO-1 activity and NMY-2 level at the cell surface, reinforce the stability of the actomyosin cortex, and resist its movement to influence cell-shape dynamics.

Original languageEnglish
Pages (from-to)103-112
Number of pages10
JournalCurrent Biology
Volume27
Issue number1
DOIs
StatePublished - 9 Jan 2017
Externally publishedYes

Funding

FundersFunder number
National Institutes of HealthP40 OD010440
National Research Foundation SingaporeCRP001-084, NRF-RF2009-RF001-074
Ministry of Education - SingaporeMOE2015-T2-1-045

    Keywords

    • C. elegans
    • HMR-1
    • NMY-2
    • RHO
    • actin cortex
    • cadherin
    • cluster
    • cytokinesis
    • myosin II
    • non-junctional

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