TULP3 is required for localization of membrane-associated proteins ARL13B and INPP5E to primary cilia

• Published in: Biochemical and biophysical research communications 2019-01, Vol.509 (1), p.227-234
• Main Authors: Han, Sarina, Miyoshi, Ko, Shikada, Sho, Amano, Genki, Wang, Yinshengzhuoma, Yoshimura, Takeshi, Katayama, Taiichi
• Format: Article
• Language: English
• Subjects: ADP-Ribosylation Factors - analysis; ADP-Ribosylation Factors - metabolism; ARL13B; Carrier Proteins - analysis; Carrier Proteins - metabolism; Cell Line; Cilia - genetics; Cilia - metabolism; Cilia - ultrastructure; CRISPR-Cas Systems; Gene Knockout Techniques; Humans; IFT-A; INPP5E; Intracellular Signaling Peptides and Proteins; Phosphoric Monoester Hydrolases - analysis; Phosphoric Monoester Hydrolases - metabolism; Primary cilia; Protein Binding; Proteins - genetics; Proteins - metabolism; TULP3
• ISSN: 0006-291X; 1090-2104
• DOI: 10.1016/j.bbrc.2018.12.109

The primary cilia are known as biosensors that transduce signals through the ciliary membrane proteins in vertebrate cells. The ciliary membrane contains transmembrane proteins and membrane-associated proteins. Tubby-like protein 3 (TULP3), a member of the tubby family, has been shown to interact with the intraflagellar transport-A complex (IFT-A) and to be involved in the ciliary localization of transmembrane proteins, although its role in the ciliary entry of membrane-associated proteins has remained unclear. Here, to determine whether TULP3 is required for the localization of ciliary membrane-associated proteins, we generated and analyzed TULP3-knockout (KO) hTERT RPE-1 (RPE1) cells. Immunofluorescence analysis demonstrated that ciliary formation was downregulated in TULP3-KO cells and that membrane-associated proteins, ADP-ribosylation factor-like 13B (ARL13B) and inositol polyphosphate-5-phosphatase E (INPP5E), failed to localize to primary cilia in TULP3-KO cells. These defects in the localization of ARL13B and INPP5E in TULP3-KO cells were rescued by the exogenous expression of wild-type TULP3, but not that of mutant TULP3 lacking the ability to bind IFT-A. In addition, the expression of TUB protein, another member of the tubby family whose endogenous expression is absent in RPE1 cells, also rescued the defective ciliary localization of ARL13B and INPP5E in TULP3-KO cells, suggesting that there is functional redundancy between TULP3 and TUB. Our findings indicate that TULP3 participates in ciliogenesis, and targets membrane-associated proteins to primary cilia via binding to IFT-A. •Formation of primary cilia is downregulated in TULP3-knockout (KO) RPE1 cells.•ARL13B and INPP5E fail to localize to primary cilia in TULP3-KO cells.•TULP3 expression in TULP3-KO cells recovers ciliary localization of ARL13B and INPP5E.•TULP3 mutation in IFT-A-binding domain disrupts recovery of ARL13B and INPP5E ciliary localization.