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RESEARCH PRODUCT
Phosphorylation of the Usher syndrome 1G protein SANS controls Magi2-mediated endocytosis.
Tina MärkerUwe WolfrumKatharina BaußHannie KremerErwin Van WijkPia JoresRonald RoepmanBarbara Knappsubject
Scaffold proteinGuanylate kinaseMolecular Sequence DataPrimary Cell CultureNerve Tissue ProteinsBiologyEndocytosisPhotoreceptor cellExocytosisMiceCiliogenesisGeneticsmedicineAnimalsHumansProtein Interaction Domains and MotifsAmino Acid SequencePhosphorylationRNA Small InterferingSensory disorders Radboud Institute for Molecular Life Sciences [Radboudumc 12]Molecular BiologyGenetics (clinical)Adaptor Proteins Signal TransducingBinding SitesGeneral MedicineClathrinEndocytosisCell biologyMice Inbred C57BLRenal disorders Radboud Institute for Molecular Life Sciences [Radboudumc 11]medicine.anatomical_structureHEK293 CellsGene Expression RegulationCiliary pocketCarrier ProteinsSterile alpha motifGuanylate KinasesSequence AlignmentUsher SyndromesPhotoreceptor Cells VertebrateProtein BindingSignal Transductiondescription
Item does not contain fulltext The human Usher syndrome (USH) is a complex ciliopathy with at least 12 chromosomal loci assigned to three clinical subtypes, USH1-3. The heterogeneous USH proteins are organized into protein networks. Here, we identified Magi2 (membrane-associated guanylate kinase inverted-2) as a new component of the USH protein interactome, binding to the multifunctional scaffold protein SANS (USH1G). We showed that the SANS-Magi2 complex assembly is regulated by the phosphorylation of an internal PDZ-binding motif in the sterile alpha motif domain of SANS by the protein kinase CK2. We affirmed Magi2's role in receptor-mediated, clathrin-dependent endocytosis and showed that phosphorylated SANS tightly regulates Magi2-mediated endocytosis. Specific depletions by RNAi revealed that SANS and Magi2-mediated endocytosis regulates aspects of ciliogenesis. Furthermore, we demonstrated the localization of the SANS-Magi2 complex in the periciliary membrane complex facing the ciliary pocket of retinal photoreceptor cells in situ. Our data suggest that endocytotic processes may not only contribute to photoreceptor cell homeostasis but also counterbalance the periciliary membrane delivery accompanying the exocytosis processes for the cargo vesicle delivery. In USH1G patients, mutations in SANS eliminate Magi2 binding and thereby deregulate endocytosis, lead to defective ciliary transport modules and ultimately disrupt photoreceptor cell function inducing retinal degeneration.
| year | journal | country | edition | language |
|---|---|---|---|---|
| 2014-01-01 | Human molecular genetics |