SPATA7 maintains a novel photoreceptor-specific zone in the distal connecting cilium.

TitleSPATA7 maintains a novel photoreceptor-specific zone in the distal connecting cilium.
Publication TypeJournal Article
Year of Publication2018
AuthorsDharmat, R, Eblimit, A, Robichaux, MA, Zhang, Z, Nguyen, T-MT, Jung, SYun, He, F, Jain, A, Li, Y, Qin, J, Overbeek, P, Roepman, R, Mardon, G, Wensel, TG, Chen, R
JournalJ Cell Biol
Date Published2018 Jun 13

Photoreceptor-specific ciliopathies often affect a structure that is considered functionally homologous to the ciliary transition zone (TZ) called the connecting cilium (CC). However, it is unclear how mutations in certain ciliary genes disrupt the photoreceptor CC without impacting the primary cilia systemically. By applying stochastic optical reconstruction microscopy technology in different genetic models, we show that the CC can be partitioned into two regions: the proximal CC (PCC), which is homologous to the TZ of primary cilia, and the distal CC (DCC), a photoreceptor-specific extension of the ciliary TZ. This specialized distal zone of the CC in photoreceptors is maintained by SPATA7, which interacts with other photoreceptor-specific ciliary proteins such as RPGR and RPGRIP1. The absence of results in the mislocalization of DCC proteins without affecting the PCC protein complexes. This collapse results in destabilization of the axonemal microtubules, which consequently results in photoreceptor degeneration. These data provide a novel mechanism to explain how genetic disruption of ubiquitously present ciliary proteins exerts tissue-specific ciliopathy phenotypes.

Alternate JournalJ. Cell Biol.
PubMed ID29899041