Evaluation Summary:
The current paper is of interest to cell biologists studying ciliogenesis and specifically vertebrate photoreceptors, which are specialized cilia. The study shows that mutations in the small GTP binding protein ARL3 known to cause dominant inherited retinal dystrophies in humans result in ARL3 hyperactivity, disrupting the normal ciliary gradient of ARL3 activity and leading to altered retinal development. The authors demonstrate restored normal nuclear distribution by overexpression of ARL3 effectors, suggesting that the active mutants disrupt nuclear migration, at least in part, by sequestering ARL3 effectors. Overall, the experiments are properly controlled, executed, and analyzed and involve a series of extensive biochemical analyses complemented with in vivo phenotypic assessment. The development of a method to analyze snapshots of the interaction between ARL3 and its interactors is also a strength of the paper, however, significant concerns remain regarding links between nuclear migration failure and ciliogenesis in the outer segment, and alternative possibilities that could explain the phenotype of the ARL3 Y90C mutant with respect to its sequestration of the GEF ARL13B. Addressing these major concerns would improve the manuscript and could have considerable impact on the field.
(This preprint has been reviewed by eLife. We include the public reviews from the reviewers here; the authors also receive private feedback with suggested changes to the manuscript. Reviewer #1 agreed to share their name with the authors.)