Biology subjects

Chamlali, M.

Publications and source records attributed to Chamlali, M..

3 recordsLinked to original sources

bioRxiv2026

NBCn1 interacts with DYNLL1 and regulates ciliary length and SUFU localization to control Sonic hedgehog signaling

Primary cilia integrate morphogen signaling with cellular physiology, yet how ion transporters contribute to ciliary organization and function remains poorly understood. Here, we identify the sodium-bicarbonate cotransporter NBCn1 (SLC4A7) as a previously unrecognized ciliary membrane component essential for regulating ciliary length and Sonic hedgehog (Shh) signaling. NBCn1 localizes to primary cilia through distinct Nand Cterminal targeting motifs and inhibition of dynein activity or loss of DLG1, a known NBCn1 interacting protein, augments its ciliary localization. Loss of NBCn1 shortens cilia without altering ciliation frequency or deciliation kinetics, indicating a selective role in ciliary elongation control rather than in ciliogenesis initiation or maintenance. NBCn1 deficiency or -inhibition leads to ciliary enrichment of SUFU even at basal level and markedly attenuates GLI1 transcriptional activation, despite intact SMO ciliary entry. Structural modeling and coimmunoprecipitation reveal that NBCn1 interacts with DYNLL1, VPS45, and the transitionzone protein TMEM216, suggesting that NBCn1 modulates ciliary length and Shh signaling through interactions with these proteins. Together, these findings uncover NBCn1 as a central regulator of ciliary length and Shh signaling, highlighting ion transport as a critical and underappreciated determinant of ciliary signaling competence. Significance statementPrimary cilia are essential cellular signaling hubs, yet the contribution of ion transporters and pH to ciliary architecture and function has remained unclear. This study identifies the bicarbonate transporter NBCn1 as a previously unrecognized regulator of ciliary length and Sonic hedgehog (Shh) signaling. We show that NBCn1 is actively trafficked into cilia through defined Nand Cterminal determinants, is exported from cilia via retrograde intraflagellar transport (IFT), and interacts directly with IFT dynein component DYNLL1. Loss of NBCn1 selectively shortens cilia while leaving ciliogenesis frequency and deciliation dynamics intact. NBCn1 deficiency disrupts the ciliary localization of the key Shh component SUFU, leading to impaired GLI transcriptional responses. By revealing how ion transport intersects with IFT and morphogen signaling, these findings establish NBCn1 as a central integrator of ciliary microenvironmental regulation and developmental signaling output, highlighting pH regulatory ion transport as a critical and underappreciated determinant of ciliary function.

cell biology↗

bioRxiv2024

Loss of KIF13B causes time-dependent changes in ciliary polycystin-2 levels and extracellular vesicle release

Dynamic control of ciliary membrane protein content is crucial for the organelles homeostasis and signaling function and involves removal of ciliary components by BBSome-mediated export, endocytic retrieval and/or extracellular vesicle (EV) shedding. We report that KIF13B regulates ciliary protein composition and EV shedding in cultured kidney epithelial cells, with effects that vary over time. In early stages of ciliation Kif13b-/- cells aberrantly accumulate PC2, FLOT1, and HGS within cilia. These cells also produce fewer small EVs through the GW4869-sensitive, nSMase2 pathway, and release large EVs enriched with CCDC198 and the centriole distal appendage protein CCDC92, which also localizes to the ciliary tip. Upon cilia maturation, Kif13b-/- cells accelerate large EV release of numerous ciliary proteins, including PC2, BBSome components, and IFT proteins, which correlates with gradual depletion of CCDC92 and PC2 from the ciliary tip and shaft, respectively. Furthermore, over time, Kif13b-/- cells show an upregulation in the release of small EVs, which differ in composition from wild-type small EVs. Specifically, the mutant small EVs lack several proteins that are enriched in small EVs from BBSome-deficient cells, such as the palmitoyl transferase ZDHHC5, which localizes to cilia, accumulates within cilia of BBSome-deficient cells, and regulates ciliary length and PC2 levels. Collectively, our work suggests that KIF13B acts at the level of centriole distal appendages to limit ciliary protein entrance and promote endocytic retrieval downstream of the BBSome. Furthermore, this study shows for the first time that CCDC198 and ZDHHC5 localize to primary cilia, suggesting they are potential novel ciliopathy candidates.

cell biology↗

bioRxiv2023

DLG1 functions upstream of SDCCAG3 and IFT20 to control targeting of polycystin-2 to the primary cilium

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 caused ciliary elongation and cystogenesis, and cell-based proximity labelling proteomics and fluorescence microscopy showed alterations in the ciliary proteome upon loss of DLG1. Specifically, the retromer-associated protein SDCCAG3, IFT20 and polycystin-2 (PC2) were reduced in cilia of DLG1 deficient cells compared to control cells. This phenotype was recapitulated in vivo and rescuable by re-expression of wildtype 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 suggested 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.

cell biology↗