An Actin Network Dispatches Ciliary GPCRs into Extracellular Vesicles to Modulate Signaling
Open accessAbstract
Signaling receptors dynamically exit cilia upon activation of signaling pathways such as Hedgehog. Here, we find that when activated G protein-coupled receptors (GPCRs) fail to undergo BBSome-mediated retrieval from cilia back into the cell, these GPCRs concentrate into membranous buds at the tips of cilia before release into extracellular vesicles named ectosomes. Unexpectedly, actin and the actin regulators drebrin and myosin 6 mediate ectosome release from the tip of cilia. Mirroring signal-dependent retrieval, signal-dependent ectocytosis is a selective and effective process that removes activated signaling molecules from cilia. Congruently, ectocytosis compensates for BBSome defects as ectocytic removal of GPR161, a negative regulator of Hedgehog signaling, permits the appropriate transduction of Hedgehog signals in Bbs mutants. Finally, ciliary receptors that lack retrieval determinants such as the anorexigenic GPCR NPY2R undergo signal-dependent ectocytosis in wild-type cells. Our data show that signal-dependent ectocytosis regulates ciliary signaling in physiological and pathological contexts.
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GPR161 is removed from primary cilia in a SMO-dependent and beta-arrestin-dependent manner after Hedgehog pathway activation.
“GPR161 is also removed from primary cilia in a SMO-dependent and β-arrestin-dependent manner following activation of HH signalling 28, 138.”
From Cellular signalling by primary cilia in development, organ function and disease (2019) · cites this paper as [28]
In Results (‘Ectocytosis compensates for retrieval defects’; page unavailable), the paper reports that Hedgehog activation reduces ciliary GPR161 and that β-arrestins are required for its usual retrieval. It also finds that GPR161 can still be removed by ectocytosis in β-arrestin-deficient cells, so removal is not strictly β-arrestin-dependent. The paper does not itself establish SMO dependence; that point appears in the title of the Pal et al. study in its references. (LLM, conf=0.86)
Experimental — accuracy not yet measuredCiliary export of activated SSTR3 in cultured renal epithelial cells requires beta-arrestin-2.
“ciliary export of activated SSTR3 in cultured renal epithelial cells also requires β-arrestin-2 28, 172.”
From Cellular signalling by primary cilia in development, organ function and disease (2019) · cites this paper as [28]
The Results section (‘Failure to retrieve GPCRs from cilia results in ectocytosis from the tip’; page unavailable) supports a role for β-arrestin-2 in retrieving activated SSTR3 from cilia in IMCD3 kidney cells. But it also reports that activated SSTR3 exits β-arrestin-2-deficient cilia by ectocytosis, so β-arrestin-2 is not required for ciliary export in general. (LLM, conf=0.84)
Experimental — accuracy not yet measuredCiliary membrane content can be modulated by ectocytosis of vesicles at the ciliary tip.
“Moreover, ciliary membrane content can be modulated by the ectocytosis of vesicles at the ciliary tip 26–28 (Figure 1).”
From Cellular signalling by primary cilia in development, organ function and disease (2019) · cites this paper as [28]
Experimental — accuracy not yet measuredActivated NPY2R accumulates at the ciliary tip and is released in ectosomes.
“activated NPY2R accumulates at the ciliary tip and is released in extracellular vesicles called ectosomes 28”
From Cellular signalling by primary cilia in development, organ function and disease (2019) · cites this paper as [28]
Agonist-dependent ciliary export of heterologously expressed SSTR3 in inner medullary collecting duct cells lacking BBSome function or beta-arrestin-2 involves active recruitment of SSTR3 to the ciliary tip and release in ectosomes.
“agonist-dependent ciliary export of heterologously-expressed SSTR3 in inner medullary collecting duct cells lacking either BBSome function or β-arrestin-2, involved active recruitment of SSTR3 to the ciliary tip from where a considerable fraction was released in ectosomes 28.”
From Cellular signalling by primary cilia in development, organ function and disease (2019) · cites this paper as [28]
Ciliary signaling regulates actin networks and drives ciliary exocytosis, linking cilium function to extracellular vesicle biogenesis.
“Ciliary signaling regulates actin networks and drives ciliary exocytosis, linking cilium function to EV biogenesis [184,185].”
From The Impact of Neurotoxin Proteins Trafficked by Primary Cilia and Extracellular Vesicles in Neurodegenerative Diseases (2025) · cites this paper as [185]
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“Ciliary signaling regulates actin networks and drives ciliary exocytosis, linking cilium function to EV biogenesis [184,185].”
- Authors
- Nager, A. R., Goldstein, J. S., Herranz-Pérez, V., Portran, D., Ye, F., Garcia-Verdugo, J. M., & Nachury, M. V.
- Affiliations
- Stanford Medicine (US)
- Corresponding author
- Nachury, Maxence V.
- Venue
- Cell
- Publisher
- Elsevier BV
- Published
- 2017-01
- Volume
- 168
- Issue
- 1-2
- Pages
- 252-263.e14
- ISSN
- 0092-8674 (ISSN-L)
- PMC
- PMC5235987
- OpenAlex
- W2561697517
- Cited by
- 366
- References
- 46
- Citations by year
- 2026: 21 · 2025: 38 · 2024: 26 · 2023: 48 · 2022: 28 · 2021: 36 · 2020: 60 · 2019: 41 · 2018: 40 · 2017: 28
- FWCI
- 29.35
- Type
- journal article
- Language
- en
- Open access
- bronze
- doi.org
- Licence
- Locations
- Cell (publishedVersion)
- PubMed (publishedVersion)
- Europe PMC (PubMed Central) (acceptedVersion)
- PubMed Central (acceptedVersion)
- eScholarship (California Digital Library) (submittedVersion, cc-by-nc-nd)
- Funders
- NIH/NIGMS (GM089933, 1S10RR02678001)
- Generalitat Valenciana (PROMETEOII/2014/075)
- Fayez Sarofim/Damon Runyon Fellowship (DRG 2160-13)
- Topics
- Life Sciences › Biochemistry, Genetics and Molecular Biology › Genetics › Genetic and Kidney Cyst Diseases
- Life Sciences › Biochemistry, Genetics and Molecular Biology › Molecular Biology › Extracellular vesicles in disease
- Life Sciences › Biochemistry, Genetics and Molecular Biology › Cell Biology › Cellular transport and secretion
- Keywords
- G protein-coupled receptors, cilia, ectosome, extracellular vesicles, actin cytoskeleton, drebrin, BBSome, Hedgehog signaling, GPR161, NPY2 receptor
- MeSH terms
- Extracellular Vesicles, Actins, Animals, Cell Line, Cilia, Humans, Kidney, Microscopy, Electron, Scanning, Signal Transduction, Receptors, Somatostatin, Receptors, G-Protein-Coupled, Mice
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