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The centriolar satellite protein AZI1 interacts with BBS4 and regulates ciliary trafficking of the BBSome
Journal article   Open access   Peer reviewed

The centriolar satellite protein AZI1 interacts with BBS4 and regulates ciliary trafficking of the BBSome

Xitiz Chamling, Seongjin Seo, Charles C Searby, Gunhee Kim, Diane C Slusarski and Val C Sheffield
PLoS genetics, Vol.10(2), pp.e1004083-e1004083
02/2014
DOI: 10.1371/journal.pgen.1004083
PMCID: PMC3923683
PMID: 24550735
url
https://doi.org/10.1371/journal.pgen.1004083View
Published (Version of record) Open Access

Abstract

Bardet-Biedl syndrome (BBS) is a well-known ciliopathy with mutations reported in 18 different genes. Most of the protein products of the BBS genes localize at or near the primary cilium and the centrosome. Near the centrosome, BBS proteins interact with centriolar satellite proteins, and the BBSome (a complex of seven BBS proteins) is believed to play a role in transporting ciliary membrane proteins. However, the precise mechanism by which BBSome ciliary trafficking activity is regulated is not fully understood. Here, we show that a centriolar satellite protein, AZI1 (also known as CEP131), interacts with the BBSome and regulates BBSome ciliary trafficking activity. Furthermore, we show that AZI1 interacts with the BBSome through BBS4. AZI1 is not involved in BBSome assembly, but accumulation of the BBSome in cilia is enhanced upon AZI1 depletion. Under conditions in which the BBSome does not normally enter cilia, such as in BBS3 or BBS5 depleted cells, knock down of AZI1 with siRNA restores BBSome trafficking to cilia. Finally, we show that azi1 knockdown in zebrafish embryos results in typical BBS phenotypes including Kupffer's vesicle abnormalities and melanosome transport delay. These findings associate AZI1 with the BBS pathway. Our findings provide further insight into the regulation of BBSome ciliary trafficking and identify AZI1 as a novel BBS candidate gene.
Microtubule-Associated Proteins - genetics Humans Zebrafish - growth & development Protein Transport - genetics Zebrafish - genetics Centrosome - metabolism Cilia - genetics Proteins - genetics Animals Gene Expression Regulation, Developmental Bardet-Biedl Syndrome - pathology Centrioles - genetics Cell Cycle Proteins - genetics Bardet-Biedl Syndrome - genetics Microtubule Proteins - genetics RNA, Small Interfering Centrioles - metabolism Mutation Zebrafish Proteins - genetics ADP-Ribosylation Factors - genetics

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