UNC-6 (netrin) stabilizes oscillatory clustering of the UNC-40 (DCC) receptor to orient polarity.
Bottom Line: By performing live-cell imaging of the DCC orthologue UNC-40 during anchor cell invasion in Caenorhabditis elegans, we have found that UNC-40 clusters, recruits F-actin effectors, and generates F-actin in the absence of UNC-6 (netrin).Together, our data suggest that UNC-6 (netrin) directs polarized responses by stabilizing UNC-40 clustering.We propose that ligand-independent UNC-40 clustering provides a robust and adaptable mechanism to polarize toward netrin.
Affiliation: Department of Biology, Duke University, Durham, NC 27708.Show MeSH
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Mentions: To further explore the UNC-6–independent activity and dynamics of UNC-40 in the AC, we first examined static images of the spatial distribution of ectopic F-actin (the output of UNC-40 activity) during the P6.p two-cell stage (an ∼1-h period) in unc-6 mutants. To facilitate analysis, we partitioned the AC’s apical and lateral cell membranes into five equally sized portions: anterior, posterior, left, right, and apical (Fig. 4 A). The basal cell membrane (in contact with the basement membrane) was not included, as it contained F-actin that was generated by integrin (see Fig. S2). Importantly, we found that 69% of the ACs (45 out of 65 ACs observed) had a single ectopic F-actin patch polarized within one of the five membrane portions. The location of the F-actin cluster was not biased to any of the five membrane domains (Fig. 4, B and C). Thus, in the absence of UNC-6, UNC-40 mediates randomly directed F-actin polarity within the AC, where we define random as unbiased F-actin patch localization in any one of the equally sized membrane regions.
Affiliation: Department of Biology, Duke University, Durham, NC 27708.