title: Cbln1 accumulates and colocalizes with Cbln3 and GluRdelta2 at parallel fiber-Purkinje cell synapses in the mouse cerebellum.
abstract: Cbln1 (a.k.a. precerebellin) is secreted from cerebellar granule cells as homohexamer or in heteromeric complexes with Cbln3. Cbln1 plays crucial roles in regulating morphological integrity of parallel fiber (PF)-Purkinje cell (PC) synapses and synaptic plasticity. Cbln1-knockout mice display severe cerebellar phenotypes that are essentially indistinguishable from those in glutamate receptor GluRdelta2-null mice, and include severe reduction in the number of PF-PC synapses and loss of long-term depression of synaptic transmission. To understand better the relationship between Cbln1, Cbln3 and GluRdelta2, we performed light and electron microscopic immunohistochemical analyses using highly specific antibodies and antigen-exposing methods, i.e. pepsin pretreatment for light microscopy and postembedding immunogold for electron microscopy. In conventional immunohistochemistry, Cbln1 was preferentially associated with non-terminal portions of PF axons in the molecular layer but rarely overlapped with Cbln3. In contrast, antigen-exposing methods not only greatly intensified Cbln1 immunoreactivity in the molecular layer, but also revealed its high accumulation in the synaptic cleft of PF-PC synapses. No such synaptic accumulation was evident at other PC synapses. Furthermore, Cbln1 now came to overlap almost completely with Cbln3 and GluRdelta2 at PF-PC synapses. Therefore, the convergence of all three molecules provides the anatomical basis for a common signaling pathway regulating circuit development and synaptic plasticity in the cerebellum.
authors.affiliation: Department of Anatomy, Hokkaido University School of Medicine, Sapporo, Japan.
authors.forename: Eriko
authors.initials: E
authors.lastname: Miura
authors.forename: Keiko
authors.initials: K
authors.lastname: Matsuda
authors.forename: James I
authors.initials: JI
authors.lastname: Morgan
authors.forename: Michisuke
authors.initials: M
authors.lastname: Yuzaki
authors.forename: Masahiko
authors.initials: M
authors.lastname: Watanabe
mesh_terms: D000818:Animals; D002531:Cerebellum / Q000378:metabolism*; D005455:Fluorescent Antibody Technique; D007150:Immunohistochemistry; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D016253:Microscopy, Immunoelectron; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000378:metabolism*; D010434:Pepsin A; D011498:Protein Precursors / Q000235:genetics / Q000378:metabolism*; D011689:Purkinje Cells / Q000378:metabolism*; D017470:Receptors, Glutamate / Q000378:metabolism*; D013569:Synapses / Q000378:metabolism*
chemical_list: C092370:Cbln1 protein, mouse; C484272:Cbln3 protein, mouse; D009419:Nerve Tissue Proteins; D011498:Protein Precursors; D017470:Receptors, Glutamate; C107913:glutamate receptor delta 2; D010434:Pepsin A