Although Hedgehog (Hh) signalling family members have known roles in animal development, little is known about their developmental function in C. elegans. Now, Alexander Soukas and colleagues investigate the role of GRD-1 and PTR-11, which encode a Hh-like ligand and patched receptor, respectively, using a combination of genetic knockdown approaches and gene expression analyses. Unexpectedly, the authors show that the rate of development accelerates by about 2 hours following RNAi knockdown of grd-1. Conversely, overexpression and CRISPR activation of grd-1 slows development. They determine that GRD-1 functions downstream of the TORC2 pathway because grd-1 knockdown can rescue the slowed growth observed in TORC2 signalling loss-of-function mutants, such as rict-1, sgk-1 and sinh-1. To uncover the receptor that transduces the GRD-1 signal, the researchers perform a screen and show that ptr-11 knockdown also accelerates development and can rescue the loss of TORC2 signalling. Furthermore, ptr-11 knockdown can rescue developmental slowing caused by grd-1 overexpression. Finally, they use RNA-sequencing to identify PQM-1 as a potential factor regulated by TORC2 activity in a GRD-1-dependent manner. Together, these data reveal a new Hedgehog-like signalling pathway that regulates developmental rate in C. elegans.
