title: Expression of Cux-1 and Cux-2 in the developing somatosensory cortex of normal and barrel-defective mice.
abstract: Recently, two orthologues of the Drosophila homeobox Cut gene, Cux-1 and Cux-2, have been identified as restricted molecular markers of upper layer (II-IV) neurons in the murine cerebral cortex. We show that during early postnatal life, from P0 to P10, Cux-1 and Cux-2 mRNA are coexpressed in all primary sensory cortices. Antisera to Cux-1 and Cux-2 immunoreactivities preferentially label neurons in the barrel walls of the primary somatosensory cortex (S1). Subsequently, Cux-1 remains enriched in sensory cortices, whereas Cux-2 expression enlarges to comprise the frontal and insular areas. The laminar distribution of Cux-1 and Cux-2 differs: Cux-1 follows a layer IV to layer II decreasing gradient of expression, whereas Cux-2 expression is homogeneous across layers IV-II. No colocalization was found with GABA and birth dating experiments showed that Cux-1-positive neurons in layer IV are born during a restricted period, E13.5-E14.5, suggesting that Cux-1 is a useful molecular marker of the glutamatergic neurons of layer IV. We examined Cux-1 and Cux-2 in barrel-defective mouse strains, the VMAT2 KO, the MAOA KO, and the Adcyl 1(brl) strain. A normal expression level of Cux-1 and Cux-2 was found in layer IV, despite the lack of segregation of the neurons as barrels. Conversely, in Reeler mice, Cux-1 and Cux-2 had a distinct laminar distribution: the Cux-1-positive neurons had an inverted deep localization, whereas the Cux-2-positive neurons were distributed throughout the cortical thickness, suggesting that Cux-2 expression is more widely expressed in the inverted cortex of reeler mutants. Our results indicate that Cux-1 is a useful marker of the layer IV neurons in S1, and that Cux-1 and Cux-2 are differently regulated in the upper layers of the cerebral cortex.
authors.affiliation: INSERM U616, Hôpital de la Pitié Salpêtrière, Paris, France.
authors.forename: Arnaud
authors.initials: A
authors.lastname: Ferrere
authors.forename: Tania
authors.initials: T
authors.lastname: Vitalis
authors.forename: Hélène
authors.initials: H
authors.lastname: Gingras
authors.forename: Patricia
authors.initials: P
authors.lastname: Gaspar
authors.forename: Olivier
authors.initials: O
authors.lastname: Cases
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D002540:Cerebral Cortex / Q000196:embryology / Q000378:metabolism / Q000648:ultrastructure; D005260:Female; D018507:Gene Expression Regulation, Developmental; D018398:Homeodomain Proteins / Q000235:genetics / Q000378:metabolism*; D008297:Male; D051379:Mice; D018345:Mice, Knockout; D008818:Mice, Neurologic Mutants; D009474:Neurons / Q000378:metabolism / Q000648:ultrastructure; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D011247:Pregnancy; D012333:RNA, Messenger / Q000378:metabolism; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism*; D013003:Somatosensory Cortex / Q000378:metabolism*
chemical_list: C000624101:Cux1 protein, mouse; C101672:Cux2 protein, mouse; D018398:Homeodomain Proteins; D009687:Nuclear Proteins; D012333:RNA, Messenger; D012097:Repressor Proteins