title: Low levels of citrin (SLC25A13) expression in adult mouse brain restricted to neuronal clusters.
abstract: The mitochondrial aspartate-glutamate carriers (AGC) aralar (SLC25A12) and citrin (SLC25A13) are components of the malate aspartate shuttle (MAS), a major intracellular pathway to transfer reducing equivalents from NADH to the mitochondrial matrix. Aralar is the main AGC isoform present in the adult brain, and it is expressed mainly in neurons. To search for the other AGC isoform, citrin, in brain glial cells, we used a citrin knockout mouse in which the lacZ gene was inserted into the citrin locus as reporter gene. In agreement with the low citrin levels known to be present in the adult mouse brain, beta-galactosidase expression was very low. Surprisingly, unlike the case with astroglial cultures that express citrin, no beta-galactosidase was found in brain glial cells. It was confined to neuronal cells within discrete neuronal clusters. Double-immunolabelling experiments showed that beta-galactosidase colocalized not with glial cell markers but with the pan-neuronal marker NeuN. The deep cerebellar nuclei and a few midbrain nuclei (reticular tegmental pontine nuclei; magnocellular red nuclei) were the regions where beta-galactosidase expression was highest, and it was up-regulated in fasted mice, as was also the case for liver beta-galactosidase. The results support the notion that glial cells have much lower AGC levels and MAS activity than neurons.
authors.affiliation: Departamento de Biología Molecular, Centro de Biología Molecular Severo Ochoa CSIC-UAM, Universidad Autónoma de Madrid, Madrid, Spain.
authors.forename: Laura
authors.initials: L
authors.lastname: Contreras
authors.forename: Almudena
authors.initials: A
authors.lastname: Urbieta
authors.forename: Keiko
authors.initials: K
authors.lastname: Kobayashi
authors.forename: Takeyori
authors.initials: T
authors.lastname: Saheki
authors.forename: Jorgina
authors.initials: J
authors.lastname: Satrústegui
mesh_terms: D000818:Animals; D001224:Aspartic Acid / Q000378:metabolism; D015415:Biomarkers / Q000032:analysis / Q000378:metabolism; D001921:Brain / Q000166:cytology / Q000378:metabolism*; D001931:Brain Mapping / Q000379:methods; D002135:Calcium-Binding Proteins / Q000032:analysis / Q000235:genetics* / Q000378:metabolism*; D004268:DNA-Binding Proteins; D005508:Food Deprivation / Q000502:physiology; D017930:Genes, Reporter / Q000502:physiology; D007150:Immunohistochemistry; D007763:Lac Operon / Q000502:physiology; D008099:Liver / Q000378:metabolism; D008293:Malates / Q000378:metabolism; D053858:Metabolic Networks and Pathways / Q000502:physiology; D051379:Mice; D018345:Mice, Knockout; D009419:Nerve Tissue Proteins / Q000378:metabolism; D009457:Neuroglia / Q000166:cytology / Q000378:metabolism; D009474:Neurons / Q000166:cytology / Q000378:metabolism*; D009687:Nuclear Proteins / Q000378:metabolism; D027361:Organic Anion Transporters / Q000032:analysis / Q000235:genetics* / Q000378:metabolism*; D013194:Staining and Labeling; D015854:Up-Regulation / Q000502:physiology; D001616:beta-Galactosidase / Q000032:analysis / Q000235:genetics / Q000378:metabolism
chemical_list: D015415:Biomarkers; D002135:Calcium-Binding Proteins; D004268:DNA-Binding Proteins; D008293:Malates; D009419:Nerve Tissue Proteins; C492380:NeuN protein, mouse; D009687:Nuclear Proteins; D027361:Organic Anion Transporters; C008822:citrin; D001224:Aspartic Acid; C030298:malic acid; D001616:beta-Galactosidase