Dendrite regeneration in C. elegans is controlled by the RAC GTPase CED-10 and the RhoGEF TIAM-1

PLoS Genet. 2022 Mar 28;18(3):e1010127. doi: 10.1371/journal.pgen.1010127. eCollection 2022 Mar.

Abstract

Neurons are vulnerable to physical insults, which compromise the integrity of both dendrites and axons. Although several molecular pathways of axon regeneration are identified, our knowledge of dendrite regeneration is limited. To understand the mechanisms of dendrite regeneration, we used the PVD neurons in C. elegans with stereotyped branched dendrites. Using femtosecond laser, we severed the primary dendrites and axon of this neuron. After severing the primary dendrites near the cell body, we observed sprouting of new branches from the proximal site within 6 hours, which regrew further with time in an unstereotyped manner. This was accompanied by reconnection between the proximal and distal dendrites, and fusion among the higher-order branches as reported before. We quantified the regeneration pattern into three aspects-territory length, number of branches, and fusion phenomena. Axonal injury causes a retraction of the severed end followed by a Dual leucine zipper kinase-1 (DLK-1) dependent regrowth from the severed end. We tested the roles of the major axon regeneration signalling hubs such as DLK-1-RPM-1, cAMP elevation, let-7 miRNA, AKT-1, Phosphatidylserine (PS) exposure/PS in dendrite regeneration. We found that neither dendrite regrowth nor fusion was affected by the axon injury pathway molecules. Surprisingly, we found that the RAC GTPase, CED-10 and its upstream GEF, TIAM-1 play a cell-autonomous role in dendrite regeneration. Additionally, the function of CED-10 in epidermal cell is critical for post-dendrotomy fusion phenomena. This work describes a novel regulatory mechanism of dendrite regeneration and provides a framework for understanding the cellular mechanism of dendrite regeneration using PVD neuron as a model system.

MeSH terms

  • Animals
  • Axons / metabolism
  • Caenorhabditis elegans Proteins* / genetics
  • Caenorhabditis elegans Proteins* / metabolism
  • Caenorhabditis elegans* / metabolism
  • Dendrites / metabolism
  • GTP Phosphohydrolases / metabolism
  • Guanine Nucleotide Exchange Factors / genetics
  • Guanine Nucleotide Exchange Factors / metabolism
  • MAP Kinase Kinase Kinases / genetics
  • Nerve Regeneration / genetics
  • Rho Guanine Nucleotide Exchange Factors / metabolism
  • T-Lymphoma Invasion and Metastasis-inducing Protein 1* / metabolism
  • rac GTP-Binding Proteins* / genetics
  • rac GTP-Binding Proteins* / metabolism

Substances

  • CED-10 protein, C elegans
  • Caenorhabditis elegans Proteins
  • Guanine Nucleotide Exchange Factors
  • RPM-1 protein, C elegans
  • Rho Guanine Nucleotide Exchange Factors
  • T-Lymphoma Invasion and Metastasis-inducing Protein 1
  • TIAM-1 protein, C elegans
  • DLK-1 protein, C elegans
  • MAP Kinase Kinase Kinases
  • GTP Phosphohydrolases
  • rac GTP-Binding Proteins