INPP5E controls ciliary localization of phospholipids and odor response in olfactory sensory neurons

Journal of Cell Science ◽

10.1242/jcs.258364 ◽

2021 ◽

pp. jcs.258364

Author(s):

Kirill Ukhanov ◽

Cedric Uytingco ◽

Warren Green ◽

Lian Zhang ◽

Stephane Schurmans ◽

...

Keyword(s):

Sensory Neurons ◽

Primary Cilia ◽

Electrical Response ◽

Joubert Syndrome ◽

Gene Replacement ◽

Inactivation Kinetics ◽

Olfactory Sensory Neurons ◽

Efficient Recovery ◽

And Function ◽

Ciliary Localization

The lipid composition of the primary cilia membrane is emerging as a critical regulator of cilia formation, maintenance, and function. Here, we show that conditional deletion of the phosphoinositide 5’-phosphatase gene, Inpp5e, causative of Joubert syndrome in terminally developed mouse olfactory sensory neurons (OSNs) led to a dramatic remodeling of ciliary phospholipids that was accompanied by marked elongation of cilia. PI(4,5)P2 normally restricted to the proximal segment redistributed to the entire length of cilia in Inpp5e knockout mice with a reduction in PI(3,4)P2 and elevation of PI(3,4,5)P3 in the dendritic knob. The redistribution of phosphoinositides impaired odor adaptation, resulting in less efficient recovery and altered inactivation kinetics of the odor-evoked electrical response and the odor-induced elevation of cytoplasmic Ca2+. Gene replacement by adenoviral expression of Inpp5e restored the ciliary localization of PI(4,5)P2 and odor response kinetics in OSNs. Our findings support the role of phosphoinositides as a modulator of the odor response and in ciliary biology of native multi-ciliated OSNs.

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INPP5E controls ciliary localization of phospholipids and odor response kinetics in a mouse model of Joubert syndrome

10.1101/451344 ◽

2018 ◽

Author(s):

Kirill Ukhanov ◽

Cedric Uytingco ◽

Warren Green ◽

Lian Zhang ◽

Stephane Schurmans ◽

...

Keyword(s):

Cell Biology ◽

Primary Cilia ◽

Membrane Lipids ◽

Phospholipid Composition ◽

Joubert Syndrome ◽

Basic Knowledge ◽

Dent Disease ◽

Inactivation Kinetics ◽

Assisted Delivery ◽

Ciliary Localization

AbstractCiliopathies manifested in part by a dysfunction of several phosphoinositide 5’phosphatases constitute Lowes, Dent disease 2 and Joubert syndromes through critical involvement of properly functioning primary cilia (PC). We showed that deletion of INPP5E under the control of OMP-Cre in mature mouse olfactory sensory neurons (OSNs) led to a dramatic redistribution of PI(4,5)P2 (PIP2) in cilia, significant reduction of PI(3,4)P2 and enrichment of PI(3,4,5)P3 in knobs. Redistribution of the phospholipids accompanied marked elongation of cilia in INPP5E-OMP knockout (KO) OSNs. Such a dramatic remodeling of phospholipid composition however did not affect other integral membrane lipids (cholesterol, sphingomyelin, glycosylated phosphaditylinositol, phosphatidylserine). Proteins known to bind with high affinity PIP2 entered the cilia of the KO OSNs. Loss of INPP5E did not affect ciliary localization of endogenous olfactory receptor M71/M72 or distribution and movement of IFT122 particles implicating independent of phospholipids mechanism of retrograde protein transport in cilia of mature OSNs. Net odor sensitivity and response magnitude as measured by EOG was not affected by the mutation. However, odor adaptation in the KO mouse was significantly impaired resulting in less efficient recovery and altered inactivation kinetics of the odor response at the EOG and single-cell level. These findings implicate phosphoinositide-dependent regulation of active Ca2+ extrusion in OSNs whereby controlling the rate of sensory adaptation.Significance statementCurrently there are little if any available treatment to cure congenital ciliopathies. This is in part due to lack of basic knowledge of cilia biology. Olfactory cilia as well as primary cilia appear to be a phospholipid privileged organelle distinct from the rest of plasma membrane albeit sharing its continuity. We characterized distribution of several critically important for cell biology phospholipids and showed that their balance, especially of PIP2, is disrupted in Joubert syndrome animal model and has functional implications. Virally assisted delivery of wild type INPP5E to the mutant OSNs was able to restore localization of PIP2 and rescued impaired response to odor.

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Cby1 promotes Ahi1 recruitment to a ring-shaped domain at the centriole–cilium interface and facilitates proper cilium formation and function

Molecular Biology of the Cell ◽

10.1091/mbc.e14-02-0735 ◽

2014 ◽

Vol 25 (19) ◽

pp. 2919-2933 ◽

Cited By ~ 40

Author(s):

Yin Loon Lee ◽

Joshua Santé ◽

Colin J. Comerci ◽

Benjamin Cyge ◽

Luis F. Menezes ◽

...

Keyword(s):

Primary Cilia ◽

Three Dimensional ◽

Joubert Syndrome ◽

Cystic Kidneys ◽

Superresolution Microscopy ◽

Close Proximity ◽

And Function ◽

Canonical Wnt ◽

Syndrome Protein ◽

Shaped Domain

Defects in centrosome and cilium function are associated with phenotypically related syndromes called ciliopathies. Cby1, the mammalian orthologue of the Drosophila Chibby protein, localizes to mature centrioles, is important for ciliogenesis in multiciliated airway epithelia in mice, and antagonizes canonical Wnt signaling via direct regulation of β-catenin. We report that deletion of the mouse Cby1 gene results in cystic kidneys, a phenotype common to ciliopathies, and that Cby1 facilitates the formation of primary cilia and ciliary recruitment of the Joubert syndrome protein Arl13b. Localization of Cby1 to the distal end of mature centrioles depends on the centriole protein Ofd1. Superresolution microscopy using both three-dimensional SIM and STED reveals that Cby1 localizes to an ∼250-nm ring at the distal end of the mature centriole, in close proximity to Ofd1 and Ahi1, a component of the transition zone between centriole and cilium. The amount of centriole-localized Ahi1, but not Ofd1, is reduced in Cby1−/− cells. This suggests that Cby1 is required for efficient recruitment of Ahi1, providing a possible molecular mechanism for the ciliogenesis defect in Cby1−/− cells.

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Interpreting the pathogenicity of Joubert Syndrome missense variants in Caenorhabditis elegans

Disease Models & Mechanisms ◽

10.1242/dmm.046631 ◽

2020 ◽

pp. dmm.046631

Author(s):

Karen I. Lange ◽

Sofia Tsiropoulou ◽

Katarzyna Kucharska ◽

Oliver E. Blacque

Keyword(s):

Caenorhabditis Elegans ◽

Primary Cilia ◽

Model Organism ◽

Joubert Syndrome ◽

Compound Heterozygous ◽

Inherited Disorders ◽

Missense Variants ◽

C Elegans ◽

Variant Alleles ◽

And Function

Ciliopathies are inherited disorders caused by defects in motile and non-motile (primary) cilia. Ciliopathy syndromes and associated gene variants are often highly pleiotropic and represent exemplars for interrogating genotype-phenotype correlations. Towards understanding disease mechanisms in the context of ciliopathy mutations, we have employed a leading model organism for cilia and ciliopathy research, Caenorhabditis elegans, together with gene editing, to characterise two missense variants (P74S, G155S) in B9D2/mksr-2 associated with Joubert Syndrome (JBTS). B9D2 functions within the Meckel syndrome (MKS) module at the ciliary base transition zone (TZ) compartment, and regulates the cilium's molecular composition and sensory/signaling functions. Quantitative assays of cilium/TZ structure and function, together with knock-in reporters, confirm both variant alleles are pathogenic in worms. G155S causes a more severe overall phenotype and disrupts endogenous MKSR-2 organisation at the TZ. Recapitulation of the patient biallelic genotype shows that compound heterozygous worms phenocopy worms homozygous for P74S. The P74S and G155S alleles also reveal evidence of a very close functional association between the B9D2-associated B9 complex and TMEM216/MKS-2. Together, these data establish C. elegans as a paradigm for interpreting JBTS mutations, and provide further insight into MKS module organisation.

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