Actin assembly and non-muscle myosin activity drive dendrite retraction in an UNC-6/Netrin dependent self-avoidance response.

Sundararajan L, Smith CJ, Watson JD, Millis BA, Tyska MJ, Miller DM
PLoS Genet. 2019 15 (6): e1008228

PMID: 31220078 · PMCID: PMC6605669 · DOI:10.1371/journal.pgen.1008228

Dendrite growth is constrained by a self-avoidance response that induces retraction but the downstream pathways that balance these opposing mechanisms are unknown. We have proposed that the diffusible cue UNC-6(Netrin) is captured by UNC-40(DCC) for a short-range interaction with UNC-5 to trigger self-avoidance in the C. elegans PVD neuron. Here we report that the actin-polymerizing proteins UNC-34(Ena/VASP), WSP-1(WASP), UNC-73(Trio), MIG-10(Lamellipodin) and the Arp2/3 complex effect dendrite retraction in the self-avoidance response mediated by UNC-6(Netrin). The paradoxical idea that actin polymerization results in shorter rather than longer dendrites is explained by our finding that NMY-1 (non-muscle myosin II) is necessary for retraction and could therefore mediate this effect in a contractile mechanism. Our results also show that dendrite length is determined by the antagonistic effects on the actin cytoskeleton of separate sets of effectors for retraction mediated by UNC-6(Netrin) versus outgrowth promoted by the DMA-1 receptor. Thus, our findings suggest that the dendrite length depends on an intrinsic mechanism that balances distinct modes of actin assembly for growth versus retraction.

MeSH Terms (13)

Actin-Related Protein 2-3 Complex Actin Cytoskeleton Actins Animals Caenorhabditis elegans Caenorhabditis elegans Proteins Dendritic Cells Membrane Proteins Myosin Heavy Chains Nerve Tissue Proteins Netrins Neurons Nonmuscle Myosin Type IIB

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