Abstract
Purpose:
Mammalian UNC119 is a polypeptide involved in ciliary vesicular trafficking in retinal photoreceptors. UNC119 interacts with GTPase Arf-like 3 (ARL3) leading to release of myristoylated cargo and recycling of UNC119. We examined the role of an UNC119 paralog (UNC119c) in zebrafish vision and retinal organization.
Methods:
The expression patterns of the three zebrafish UNC119 and ARL3 orthologs were determined by whole mount in-situ hybridization. Visual development was studied through optomotor response analysis in UNC119c knockdown, compared to wild-type zebrafish, and rescue controls.
Results:
The three unc119 zebrafish orthologs (UNC119a-c) and arl3l2 were cloned, and their expression patterns were determined by whole mount in-situ hybridization. UNC119c and ARL3l2 are specifically expressed in photoreceptive tissues (pineal and retina). At 24 hours post fertilization (pf), a specific expression of unc119c was found in the pineal gland of the embryo and by 3 days pf, unc119c mRNA was first evident in the ventral patch of the retina. The expression of unc119c within the retina expanded with the expansion of the developing retina. In addition to their co-localization, unc119C was found to specifically interact with ARL3L2 by co-immuno precipitation. Following injection of morpholino-modified antisense oligonucleotides (MO) directed to block unc119C expression, UNC119MO, larvae displayed impaired visual acuity when compared to wild-type controls and to MO-controls as indicated by their optomotor response to grating motion.
Conclusions:
Zebrafish UNC119c is a novel ortholog of the mammalian UNC119. UNC119c and ARL3l2 interact and are highly expressed in photoreceptive tissues (pineal and retina). Knockdown of the unc119c resulted in early onset visual impairment despite the existence of other UNC119 isoforms in zebrafish. Further research on the role of ARL3 and the interactions of ARL3 and UNC119c in the zebrafish model of cilopathies is currently underway.
Keywords: 457 ciliary processes •
533 gene/expression •
689 retina: distal (photoreceptors, horizontal cells, bipolar cells)