PT  - JOURNAL ARTICLE
AU  - Jamie K. Alan
AU  - Sara Robinson
AU  - Katie Magsig
AU  - Rafael S. Demarco
AU  - Erik A. Lundquist
TI  - The Atypical Rho GTPase CHW-1 Works With SAX-3/Robo to Mediate Axon Guidance in <em>Caenorhabditis elegans</em>
AID  - 10.1101/265066
DP  - 2018 Jan 01
TA  - bioRxiv
PG  - 265066
4099  - http://biorxiv.org/content/early/2018/02/13/265066.short
4100  - http://biorxiv.org/content/early/2018/02/13/265066.full
AB  - During development, neuronal cells extend an axon towards their target destination in response to a cue to form a properly functioning nervous system. Rho proteins, Ras-related small GTPases that regulate cytoskeletal organization and dynamics, cell adhesion, and motility, are known to regulate axon guidance. Despite extensive knowledge about canonical Rho proteins (RhoA/Rac1/Cdc42), little is known about the Caenorhabditis elegans (C. elegans) atypical Cdc42-like family members CHW-1 and CRP-1 in regards to axon pathfinding and neuronal migration. chw-1(Chp/Wrch) encodes a protein that resembles human Chp (Wrch-2/RhoV) and Wrch-1 (RhoU), and crp-1 encodes for a protein that resembles TC10 and TCL. Here, we show that chw-1 works redundantly with crp-1 and cdc-42 in axon guidance. Furthermore, proper levels of chw-1 expression and activity are required for proper axon guidance. When examining CHW-1 GTPase mutants, we found that the native CHW-1 protein is likely partially activated, and mutations at a conserved residue (position 12 using Ras numbering, position 18 in CHW-1) alter axon guidance and neural migration. Additionally, we showed that chw-1 genetically interacts with the guidance receptor sax-3 in PDE neurons. Finally, in VD/DD motor neurons, chw-1 works downstream of sax-3 to control axon guidance. In summary, this is the first study implicating the atypical Rho GTPases chw-1 and crp-1 in axon guidance. Furthermore, this is the first evidence of genetic interaction between chw-1 and the guidance receptor sax-3. These data suggest that chw-1 is likely acting downstream and/or in parallel to sax-3 in axon guidance.