DLG1 functions upstream of SDCCAG3 and IFT20 to control ciliary targeting of polycystin-2

• Published in: EMBO reports 2024-07, Vol.25 (7), p.3040-3063
• Main Authors: Rezi, Csenge K, Aslanyan, Mariam G, Diwan, Gaurav D, Cheng, Tao, Chamlali, Mohamed, Junger, Katrin, Anvarian, Zeinab, Lorentzen, Esben, Pauly, Kleo B, Afshar-Bahadori, Yasmin, Fernandes, Eduardo FA, Qian, Feng, Tosi, Sébastien, Christensen, Søren T, Pedersen, Stine F, Strømgaard, Kristian, Russell, Robert B, Miner, Jeffrey H, Mahjoub, Moe R, Boldt, Karsten, Roepman, Ronald, Pedersen, Lotte B
• Format: Article
• Language: English
• Subjects: Animals; Biomedical and Life Sciences; Carrier Proteins - genetics; Carrier Proteins - metabolism; Cilia - metabolism; Discs Large Homolog 1 Protein - metabolism; EMBO05; EMBO20; EMBO24; Epithelial Cells - metabolism; Humans; Kidney - metabolism; Life Sciences; Membrane Proteins - genetics; Membrane Proteins - metabolism; Mice; Mice, Knockout; Protein Binding; Protein Transport; TRPP Cation Channels - genetics; TRPP Cation Channels - metabolism; Urogenital Abnormalities; Vesico-Ureteral Reflux - genetics; Vesico-Ureteral Reflux - metabolism
• ISSN: 1469-3178; 1469-3178
• DOI: 10.1038/s44319-024-00170-1

Polarized vesicular trafficking directs specific receptors and ion channels to cilia, but the underlying mechanisms are poorly understood. Here we describe a role for DLG1, a core component of the Scribble polarity complex, in regulating ciliary protein trafficking in kidney epithelial cells. Conditional knockout of Dlg1 in mouse kidney causes ciliary elongation and cystogenesis, and cell-based proximity labeling proteomics and fluorescence microscopy show alterations in the ciliary proteome upon loss of DLG1. Specifically, the retromer-associated protein SDCCAG3, IFT20, and polycystin-2 (PC2) are reduced in the cilia of DLG1-deficient cells compared to control cells. This phenotype is recapitulated in vivo and rescuable by re-expression of wild-type DLG1, but not a Congenital Anomalies of the Kidney and Urinary Tract (CAKUT)-associated DLG1 variant, p.T489R. Finally, biochemical approaches and Alpha Fold modelling suggest that SDCCAG3 and IFT20 form a complex that associates, at least indirectly, with DLG1. Our work identifies a key role for DLG1 in regulating ciliary protein composition and suggests that ciliary dysfunction of the p.T489R DLG1 variant may contribute to CAKUT. Synopsis The Scribble polarity complex protein DLG1 regulates ciliary length and protein composition in kidney epithelial cells. A Congenital Anomalies of the Kidney and Urinary Tract (CAKUT)-associated DLG1 variant may be associated with ciliary dysfunction. Loss of DLG1 causes ciliary elongation in kidney epithelial cells. Loss of DLG1 impairs targeting of SDCCAG3, IFT20 and PC2 to the primary cilium of kidney epithelial cells. The CAKUT-associated p.T489R DLG1 fails to rescue ciliary defects of Dlg1 -/- cells, indicating a possible ciliary involvement in CAKUT disease etiology. The Scribble polarity complex protein DLG1 regulates ciliary length and protein composition in kidney epithelial cells. A Congenital Anomalies of the Kidney and Urinary Tract (CAKUT)-associated DLG1 variant may be associated with ciliary dysfunction.