title: Glycoprotein M6a is present in glutamatergic axons in adult rat forebrain and cerebellum.
abstract: Glycoprotein M6a is a neuronally expressed member of the proteolipid protein (PLP) family of tetraspans. In vitro studies suggested a potential role in neurite outgrowth and spine formation and previous investigations have identified M6a as a stress-regulated gene. To investigate whether the distribution of M6a correlates with neuronal structures susceptible to alterations in response to stress, we localized M6a expression in neurons of hippocampal formation, prefrontal cortex and cerebellum using in situ hybridization and confocal immunofluorescence microscopy. In situ hybridization confirmed that M6a is expressed in dentate gyrus and cerebellar granule neurons and in hippocampal and cortical pyramidal neurons. Confocal microscopy localized M6a immunoreactivity to distinct sites within axonal membranes, but not in dendrites or neuronal somata. Moreover, M6a colocalized with synaptic markers of glutamatergic, but not GABAergic nerve terminals. M6a expression in the adult brain is particularly strong in unmyelinated axonal fibers, i.e. cerebellar parallel and hippocampal mossy fibers. In contrast, myelinated axons exhibit only minimal M6a immunoreactivity localized exclusively to terminal regions. The present neuroanatomical data demonstrate that M6a is an axonal component of glutamatergic neurons and that it is localized to distinct sites of the axonal plasma membrane of pyramidal and granule cells.
authors.affiliation: Clinical Neurobiology Laboratory, German Primate Center, Kellnerweg 4, 37077 Göttingen, Germany.
authors.forename: Ben
authors.initials: B
authors.lastname: Cooper
authors.forename: Hauke B
authors.initials: HB
authors.lastname: Werner
authors.forename: Gabriele
authors.initials: G
authors.lastname: Flügge
mesh_terms: D000818:Animals; D001369:Axons / Q000378:metabolism*; D002531:Cerebellum / Q000378:metabolism*; D005455:Fluorescent Antibody Technique; D015870:Gene Expression; D005973:Glutamine; D017403:In Situ Hybridization; D008297:Male; D008562:Membrane Glycoproteins / Q000096:biosynthesis*; D018613:Microscopy, Confocal; D009419:Nerve Tissue Proteins / Q000378:metabolism*; D016548:Prosencephalon / Q000378:metabolism*; D012333:RNA, Messenger / Q000032:analysis; D051381:Rats; D017207:Rats, Sprague-Dawley; D050496:Vesicular Glutamate Transport Proteins / Q000378:metabolism
chemical_list: D008562:Membrane Glycoproteins; D009419:Nerve Tissue Proteins; D012333:RNA, Messenger; D050496:Vesicular Glutamate Transport Proteins; D005973:Glutamine