title: in vivo localization of the neuronal ceroid lipofuscinosis proteins, CLN3 and CLN7, at endogenous expression levels.
abstract: The neuronal ceroid lipofuscinoses are a group of recessively inherited, childhood-onset neurodegenerative conditions. Several forms are caused by mutations in genes encoding putative lysosomal membrane proteins. Studies of the cell biology underpinning these disorders are hampered by the poor antigenicity of the membrane proteins, which makes visualization of the endogenous proteins difficult. We have used Drosophila to generate knock-in YFP-fusions for two of the NCL membrane proteins: CLN7 and CLN3. The YFP-fusions are expressed at endogenous levels and the proteins can be visualized live without the need for overexpression. Unexpectedly, both CLN7 and CLN3 have restricted expression in the CNS of Drosophila larva and are predominantly expressed in the glia that form the insect blood-brain-barrier. CLN7 is also expressed in neurons in the developing visual system. Analogous with murine CLN3, Drosophila CLN3 is strongly expressed in the excretory and osmoregulatory Malpighian tubules, but the knock-in also reveals unexpected localization of the protein to the apical domain adjacent to the lumen. In addition, some CLN3 protein in the tubules is localized within mitochondria. Our in vivo imaging of CLN7 and CLN3 suggests new possibilities for function and promotes new ideas about the cell biology of the NCLs.
authors.affiliation: Institute of Cancer and Genomic Sciences, College of Medical and Dental Sciences, University of Birmingham, Birmingham B15 2TT, UK.
authors.forename: Alamin
authors.initials: A
authors.lastname: Mohammed
authors.affiliation: Department of Developmental Neurobiology, King's College London, London SE1 1UL, UK.
authors.forename: Megan B
authors.initials: MB
authors.lastname: O'Hare
authors.affiliation: Centre for Ultrastructural Imaging, King's College London, London, SE1 1UL, UK.
authors.forename: Alice
authors.initials: A
authors.lastname: Warley
authors.affiliation: Department of Developmental Neurobiology, King's College London, London SE1 1UL, UK. Electronic address: guy.tear@kcl.ac.uk.
authors.forename: Guy
authors.initials: G
authors.lastname: Tear
authors.affiliation: Institute of Cancer and Genomic Sciences, College of Medical and Dental Sciences, University of Birmingham, Birmingham B15 2TT, UK; Department of Developmental Neurobiology, King's College London, London SE1 1UL, UK. Electronic address: r.i.tuxworth@bham.ac.uk.
authors.forename: Richard I
authors.initials: RI
authors.lastname: Tuxworth
mesh_terms: D000818:Animals; D001812:Blood-Brain Barrier / Q000737:chemistry / Q000378:metabolism* / Q000648:ultrastructure; D004330:Drosophila; D029721:Drosophila Proteins / Q000032:analysis / Q000096:biosynthesis* / Q000235:genetics; D015870:Gene Expression; D055879:Gene Knock-In Techniques; D008317:Malpighian Tubules / Q000737:chemistry / Q000378:metabolism* / Q000648:ultrastructure; D008565:Membrane Proteins / Q000032:analysis / Q000096:biosynthesis* / Q000235:genetics; D026901:Membrane Transport Proteins / Q000032:analysis / Q000096:biosynthesis* / Q000235:genetics; D009472:Neuronal Ceroid-Lipofuscinoses / Q000235:genetics / Q000378:metabolism*; D009474:Neurons / Q000737:chemistry / Q000378:metabolism* / Q000648:ultrastructure
chemical_list: C538715:CLN3 protein, Drosophila; D029721:Drosophila Proteins; C522398:MFSD8 protein, human; D008565:Membrane Proteins; D026901:Membrane Transport Proteins
keywords: Batten disease; CLN3; CLN7; Drosophila; Localization; MFSD8; Neuronal ceroid lipofuscinosis