Cilia or eukaryotic flagella are microtubule-based organelles found across the eukaryotic tree of life. Their very high aspect ratio and crowded interior are unfavorable to diffusive transport of most components required for their assembly and maintenance. Instead, a system of intraflagellar transport (IFT) trains moves cargo rapidly up and down the cilium (Figure 1A).1-3 Anterograde IFT, from the cell body to the ciliary tip, is driven by kinesin-II motors, whereas retrograde IFT is powered by cytoplasmic dynein-1b motors.4 Both motors are associated with long chains of IFT protein complexes, known as IFT trains, and their cargoes.5-8 The conversion from anterograde to retrograde motility at the ciliary tip involves (1) the dissociation of kinesin motors from trains,9 (2) a fundamental restructuring of the train from the anterograde to the retrograde architecture,8,10,11 (3) the unloading and reloading of cargo,2 and (4) the activation of the dynein motors.8,12 A prominent hypothesis is that there is dedicated calcium-dependent protein-based machinery at the ciliary tip to mediate these processes.4,13 However, the mechanisms of IFT turnaround have remained elusive. In this study, we use mechanical and chemical methods to block IFT at intermediate positions along the cilia of the green algae Chlamydomonas reinhardtii, in normal and calcium-depleted conditions. We show that IFT turnaround, kinesin dissociation, and dynein-1b activation can consistently be induced at arbitrary distances from the ciliary tip, with no stationary tip machinery being required. Instead, we demonstrate that the anterograde-to-retrograde conversion is a calcium-independent intrinsic ability of IFT.

• Klíčová slova
• TIRF microscopy, cilia and flagella, ciliary tip, intraflagellar transport, micromanipulator, total-internal reflection microscopy,
• MeSH
• biologický transport MeSH
• cilie metabolismus   MeSH
• cytoplazmatické dyneiny metabolismus   MeSH
• dyneiny * metabolismus   MeSH
• flagella fyziologie   MeSH
• kineziny * MeSH
• vápník metabolismus   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• cytoplazmatické dyneiny MeSH
• dyneiny * MeSH
• kineziny * MeSH
• vápník MeSH

Vertebrate primary cilium is a Hedgehog signaling center but the extent of its involvement in other signaling systems is less well understood. This report delineates a mechanism by which fibroblast growth factor (FGF) controls primary cilia. Employing proteomic approaches to characterize proteins associated with the FGF-receptor, FGFR3, we identified the serine/threonine kinase intestinal cell kinase (ICK) as an FGFR interactor. ICK is involved in ciliogenesis and participates in control of ciliary length. FGF signaling partially abolished ICK's kinase activity, through FGFR-mediated ICK phosphorylation at conserved residue Tyr15, which interfered with optimal ATP binding. Activation of the FGF signaling pathway affected both primary cilia length and function in a manner consistent with cilia effects caused by inhibition of ICK activity. Moreover, knockdown and knockout of ICK rescued the FGF-mediated effect on cilia. We provide conclusive evidence that FGF signaling controls cilia via interaction with ICK.

• Klíčová slova
• FGFR, ICK, cilia length, fibroblast growth factor, intestinal cell kinase,
• MeSH
• buňky NIH 3T3 MeSH
• cilie metabolismus   MeSH
• CRISPR-Cas systémy MeSH
• fibroblastové růstové faktory metabolismus   MeSH
• fosforylace MeSH
• HEK293 buňky MeSH
• interakční proteinové domény a motivy MeSH
• lidé MeSH
• modely u zvířat MeSH
• myši knockoutované MeSH
• myši MeSH
• protein-serin-threoninkinasy genetika   metabolismus   MeSH
• proteiny hedgehog metabolismus   MeSH
• proteomika MeSH
• receptor fibroblastových růstových faktorů, typ 1 metabolismus   MeSH
• receptor fibroblastových růstových faktorů, typ 3 genetika   metabolismus   MeSH
• receptor fibroblastových růstových faktorů, typ 4 metabolismus   MeSH
• receptory fibroblastových růstových faktorů genetika   metabolismus   MeSH
• signální transdukce MeSH
• simulace molekulového dockingu MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Research Support, N.I.H., Extramural MeSH
• Názvy látek
• CILK1 protein, human MeSH Prohlížeč
• Cilk1 protein, mouse MeSH Prohlížeč
• FGFR1 protein, human MeSH Prohlížeč
• FGFR3 protein, human MeSH Prohlížeč
• FGFR4 protein, human MeSH Prohlížeč
• fibroblastové růstové faktory MeSH
• protein-serin-threoninkinasy MeSH
• proteiny hedgehog MeSH
• receptor fibroblastových růstových faktorů, typ 1 MeSH
• receptor fibroblastových růstových faktorů, typ 3 MeSH
• receptor fibroblastových růstových faktorů, typ 4 MeSH
• receptory fibroblastových růstových faktorů MeSH

Cilia project from almost every cell integrating extracellular cues with signaling pathways. Constitutive activation of FGFR3 signaling produces the skeletal disorders achondroplasia (ACH) and thanatophoric dysplasia (TD), but many of the molecular mechanisms underlying these phenotypes remain unresolved. Here, we report in vivo evidence for significantly shortened primary cilia in ACH and TD cartilage growth plates. Using in vivo and in vitro methodologies, our data demonstrate that transient versus sustained activation of FGF signaling correlated with different cilia consequences. Transient FGF pathway activation elongated cilia, while sustained activity shortened cilia. FGF signaling extended primary cilia via ERK MAP kinase and mTORC2 signaling, but not through mTORC1. Employing a GFP-tagged IFT20 construct to measure intraflagellar (IFT) speed in cilia, we showed that FGF signaling affected IFT velocities, as well as modulating cilia-based Hedgehog signaling. Our data integrate primary cilia into canonical FGF signal transduction and uncover a FGF-cilia pathway that needs consideration when elucidating the mechanisms of physiological and pathological FGFR function, or in the development of FGFR therapeutics.

• MeSH
• achondroplazie genetika   patofyziologie   MeSH
• buňky NIH 3T3 MeSH
• chondrocyty metabolismus   MeSH
• chrupavka metabolismus   MeSH
• cilie patologie   fyziologie   MeSH
• ciliopatie genetika   patofyziologie   MeSH
• fenotyp MeSH
• fibroblastové růstové faktory metabolismus   MeSH
• lidé MeSH
• myši MeSH
• primární buněčná kultura MeSH
• receptor fibroblastových růstových faktorů, typ 3 genetika   metabolismus   MeSH
• růstová ploténka metabolismus   MeSH
• signální transdukce fyziologie   MeSH
• thanatoforní dysplazie genetika   patofyziologie   MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Research Support, N.I.H., Extramural MeSH
• Názvy látek
• FGFR3 protein, human MeSH Prohlížeč
• fibroblastové růstové faktory MeSH
• receptor fibroblastových růstových faktorů, typ 3 MeSH

The short rib polydactyly syndromes (SRPS) are a group of recessively inherited, perinatal-lethal skeletal disorders primarily characterized by short ribs, shortened long bones, varying types of polydactyly and concomitant visceral abnormalities. Mutations in several genes affecting cilia function cause SRPS, revealing a role for cilia function in skeletal development. To identify additional SRPS genes and discover novel ciliary molecules required for normal skeletogenesis, we performed exome sequencing in a cohort of patients and identified homozygosity for a missense mutation, p.E80K, in Intestinal Cell Kinase, ICK, in one SRPS family. The p.E80K mutation abolished serine/threonine kinase activity, resulting in altered ICK subcellular and ciliary localization, increased cilia length, aberrant cartilage growth plate structure, defective Hedgehog and altered ERK signalling. These data identify ICK as an SRPS-associated gene and reveal that abnormalities in signalling pathways contribute to defective skeletogenesis.

• MeSH
• cilie genetika   patologie   MeSH
• exom genetika   MeSH
• kojenec MeSH
• kostra abnormality   růst a vývoj   MeSH
• lidé MeSH
• MAP kinasový signální systém MeSH
• mnohočetné abnormality genetika   patofyziologie   MeSH
• protein-serin-threoninkinasy genetika   MeSH
• proteiny hedgehog genetika   MeSH
• rodokmen MeSH
• sekvenční analýza DNA MeSH
• signální transdukce MeSH
• syndrom krátkého žebra a polydaktylie genetika   patologie   MeSH
• těhotenství MeSH
• Check Tag
• kojenec MeSH
• lidé MeSH
• těhotenství MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• CILK1 protein, human MeSH Prohlížeč
• protein-serin-threoninkinasy MeSH
• proteiny hedgehog MeSH