Biology subjects

Campestre, F.

Publications and source records attributed to Campestre, F..

3 recordsLinked to original sources

bioRxiv2026

Primary cilia coordinate c-KIT signaling induced proliferation in alpha cells

Circulating glucagon levels are elevated in patients with diabetes and obesity and contribute to hyperglycemia. The mechanisms underlying hyperglucagonemia remain poorly understood, but expansion of pancreatic -cell mass is thought to play an important role. Primary cilia are sensory organelles that act as signaling hubs, for pathways controlling cell differentiation, proliferation, and function, yet their contribution to -cell biology remains poorly defined. Here we investigated the role of primary cilia in the regulation of -cell proliferation. To this end we generated the first -cell primary cilia proteome identifying 167 cilia-enriched proteins. Among these, we identified and validated the proto-oncogene receptor tyrosine kinase, c-KIT, as a novel ciliary receptor in -cells. We further show that c-KIT signaling depends on intact primary cilia and that stimulation of isolated mouse islets with its endogenous ligand, stem cell factor (SCF), promotes -cell proliferation. In human pancreatic islets KITLG mRNA expression, but not KIT mRNA expression, correlated positively with donor BMI, suggesting that increased ligand availability drives c-KIT signaling in obesity. Together, our findings identify the primary cilium as a signaling platform c-KIT in cells and reveal a ciliary axis that may drive -cell expansion and hyperglucagonemia in obesity and diabetes.

physiology↗

bioRxiv2026

Analysis of motor-based transport in primary cilia by dynamic mode decomposition of live-cell imaging data

Kinesin-3 motor proteins are increasingly recognized for their important roles in cilia. The mammalian kinesin-3 motor KIF13B moves bidirectionally in primary cilia and regulates ciliary content, but its relationship to the intraflagellar transport (IFT) machinery is unclear. Here, we combine quantitative live-cell imaging with a new kymograph analysis based on dynamic mode decomposition (DMD) to separate mobile from immobile protein populations in primary cilia. This approach simplifies extraction of molecular velocities from kymographs and reveals that a KIF13B deletion mutant retaining only the motor domain and part of the forkhead-associated domain does not alter steady-state IFT velocity or frequency. However, when retrograde dynein-2 function is inhibited by Ciliobrevin D, both anterograde and retrograde IFT velocities decrease in parental cells, as expected, but remain unchanged in KIF13B mutant cells. Structured illumination, confocal, and STED microscopy further show that KIF13B localizes to the ciliary membrane and concentrates at the periciliary membrane region and the centriolar subdistal appendages, below the distal appendage marker FBF1. Our improved kymograph approach provides new insight into KIF13B ciliary function and simplifies the quantitative analysis of ciliary protein transport.

biophysics↗

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↗