title: Abnormal laminar position and dendrite development of interneurons in the reeler forebrain.
abstract: The majority of cortical and hippocampal interneurons originate in the subcortical telencephalon and migrate tangentially into pallial regions before settling in various cortical layers. The molecular cues that regulate final positioning of specific interneurons in cortical structures have not yet been identified. The positioning of radially migrating principal neurons of the cortex and hippocampus depends upon Reelin, an extracellular protein expressed near the pial surface during embryonic development that is absent in reeler mutant mice. To determine whether the layer specification of interneurons, like that of principal neurons, requires Reelin, we crossed reeler with transgenic mice that contain Green Fluorescent Protein (GFP)-expressing Inhibitory Neurons (GINs). These neurons express basal forebrain markers Dlx1/2 in normal and reeler mice. In normal mice, GINs express Reelin and are localized to specific layers of the cortex and hippocampus. In reeler mutant mice, we show that GINs migrate normally into the pallium, but fail to acquire proper layer position. Double labeling experiments indicate that the neurochemical profile of these interneurons is not generally altered in reeler mice. However, the extension of their cellular processes is abnormal. Quantitative analysis of GINs in the cortex revealed that they are hypertrophic, bearing longer neuritic branches than normal. Thus, the lack of Reelin signaling results in abnormal positioning and altered morphology of forebrain interneurons.
authors.affiliation: The Cain Foundation Laboratories, Texas Children's Hospital, Baylor College of Medicine, Houston, TX 77030, USA.
authors.forename: Odessa
authors.initials: O
authors.lastname: Yabut
authors.forename: Amy
authors.initials: A
authors.lastname: Renfro
authors.forename: Sanyong
authors.initials: S
authors.lastname: Niu
authors.forename: John W
authors.initials: JW
authors.lastname: Swann
authors.forename: Oscar
authors.initials: O
authors.lastname: Marín
authors.forename: Gabriella
authors.initials: G
authors.lastname: D'Arcangelo
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D019521:Body Patterning / Q000502:physiology; D002452:Cell Count; D002465:Cell Movement / Q000502:physiology; D003712:Dendrites / Q000502:physiology*; D018507:Gene Expression Regulation, Developmental / Q000502:physiology; D049452:Green Fluorescent Proteins / Q000235:genetics; D006624:Hippocampus / Q000166:cytology / Q000502:physiology; D018398:Homeodomain Proteins / Q000378:metabolism; D007395:Interneurons / Q000166:cytology*; D051379:Mice; D008818:Mice, Neurologic Mutants / Q000033:anatomy & histology*; D008822:Mice, Transgenic; D016548:Prosencephalon / Q000002:abnormalities* / Q000166:cytology*; D000091042:Reelin Protein; D014157:Transcription Factors / Q000378:metabolism
chemical_list: C088334:Distal-less homeobox proteins; D018398:Homeodomain Proteins; D000091042:Reelin Protein; D014157:Transcription Factors; D049452:Green Fluorescent Proteins; C000717128:Reln protein, mouse