title: Altered sensitivity of cerebellar granule cells to glutamate receptor overactivation in the Cln3(Δex7/8)-knock-in mouse model of juvenile neuronal ceroid lipofuscinosis.
abstract: The juvenile onset form of neuronal ceroid lipofuscinoses (JNCL) is a recessively inherited lysosomal storage disorder characterized by progressive neurodegeneration. JNCL results from mutations in the CLN3 gene that encodes a lysosomal membrane protein with unknown function. Utilizing a Cln3-knock-out mouse model of JNCL that was created on the 129S6/SvEv genetic background, we have previously demonstrated that CLN3-deficient cerebellar granule cells (CGCs) have a selectively increased sensitivity to AMPA-type glutamate receptor-mediated toxicity. Our recent findings that CGCs from 129S6/SvEv and C57BL/6J wild type (WT) mice have significant differences in glutamate receptor expression and in excitotoxic vulnerability indicated that the genetic background possibly have a strong influence on how glutamate receptor function is dysregulated in CLN3-deficient neurons. Indeed, here we show that in the Cln3(Δex7/8)-knock-in mouse model, that is on the C57BL/6J genetic background, mimics the most frequent mutation observed in JNCL patients and considered a null mutant, the sensitivity of CGCs to both AMPA- and NMDA-type glutamate receptor overactivations is altered. Cultured wild type and Cln3(Δex7/8) CGCs were equally sensitive to AMPA toxicity after 2 or 3 weeks in vitro, whereas the subunit-selective AMPA receptor agonist, CPW-399, induced significantly more cell death in mature, 3-week-old Cln3(Δex7/8) cultures. NMDA receptor-mediated toxicity changed during in vitro development: Cln3(Δex7/8) CGCs were less sensitive to high concentration of NMDA after 2 weeks in culture but became more vulnerable than their WT counterparts after 3 weeks in vitro. Abnormally altered glutamate receptor function in the cerebellum may result in motor deficits, and we confirmed that 7-week-old Cln3(Δex7/8) mice, similarly to Cln3-knock-out mice, have a motor coordination deficit as measured by an accelerating rotarod. Our results demonstrate altered glutamate receptor function in Cln3(Δex7/8) neurons and suggest that both AMPA and NMDA receptors are potential therapeutic targets in JNCL.
authors.affiliation: Center for Neural Development and Disease, University of Rochester School of Medicine and Dentistry, Rochester, NY 14642, USA.
authors.forename: Rozzy
authors.initials: R
authors.lastname: Finn
authors.forename: Attila D
authors.initials: AD
authors.lastname: Kovács
authors.forename: David A
authors.initials: DA
authors.lastname: Pearce
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D002531:Cerebellum / Q000378:metabolism*; D003594:Cytoplasmic Granules / Q000378:metabolism*; D055879:Gene Knock-In Techniques; D008562:Membrane Glycoproteins / Q000235:genetics / Q000502:physiology*; D051379:Mice; D008810:Mice, Inbred C57BL; D018832:Molecular Chaperones / Q000235:genetics / Q000502:physiology*; D009472:Neuronal Ceroid-Lipofuscinoses / Q000235:genetics / Q000378:metabolism*; D017470:Receptors, Glutamate / Q000378:metabolism*; D045442:Rotarod Performance Test
chemical_list: C102229:CLN3 protein, mouse; D008562:Membrane Glycoproteins; D018832:Molecular Chaperones; D017470:Receptors, Glutamate