title: Layer positioning of late-born cortical interneurons is dependent on Reelin but not p35 signaling.
abstract: We tested the response of interneurons to the absence of Reelin signaling or p35 in the mouse neocortex. We provide three independent strands of evidence to demonstrate that layering of late-born (but not early-born) interneurons is regulated by Reelin signaling. First, early-born and late-born interneurons behaved differently in mice lacking Reelin or disabled 1 (Dab1). Early-born interneurons showed layer inversion, whereas late-born interneurons did not demonstrate layer inversion but were randomly distributed across the cortex. Second, in p35 mutant brains (in which Reelin signaling is intact), late-born interneurons are appropriately positioned in the upper layers despite the malpositioning of all other cortical neurons in these mice. Third, transplanted late-born interneuron precursors (wild type) into Dab1(-/-) cortices showed appropriate upper layer segregation. Together, these results indicate that, in the absence of Reelin signaling, late-born interneurons fail to laminate properly, and this is restored in an environment in which Reelin signaling is intact. These studies suggest different mechanisms for the stratification of cortical interneurons. Whereas the early-born interneurons appear to be associated with projection neuron layering, late-born interneurons rely on Reelin signaling for their correct lamination.
authors.affiliation: Howard Florey Institute, The University of Melbourne, Parkville 3010, Victoria, Australia.
authors.forename: Vicki
authors.initials: V
authors.lastname: Hammond
authors.forename: Eva
authors.initials: E
authors.lastname: So
authors.forename: Jenny
authors.initials: J
authors.lastname: Gunnersen
authors.forename: Helen
authors.initials: H
authors.lastname: Valcanis
authors.forename: Michael
authors.initials: M
authors.lastname: Kalloniatis
authors.forename: Seong-Seng
authors.initials: SS
authors.lastname: Tan
mesh_terms: D000818:Animals; D015816:Cell Adhesion Molecules, Neuronal / Q000235:genetics / Q000502:physiology*; D016326:Extracellular Matrix Proteins / Q000235:genetics / Q000502:physiology*; D007395:Interneurons / Q000166:cytology* / Q000201:enzymology / Q000637:transplantation; D008297:Male; D051379:Mice; D018345:Mice, Knockout; D008818:Mice, Neurologic Mutants; D019579:Neocortex / Q000166:cytology* / Q000196:embryology*; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000502:physiology*; D010770:Phosphotransferases / Q000235:genetics / Q000502:physiology*; D000091042:Reelin Protein; D012697:Serine Endopeptidases / Q000235:genetics / Q000502:physiology*; D015398:Signal Transduction
chemical_list: C492236:Cdk5r1 protein, mouse; D015816:Cell Adhesion Molecules, Neuronal; C103773:Dab1 protein, mouse; D016326:Extracellular Matrix Proteins; D009419:Nerve Tissue Proteins; D000091042:Reelin Protein; D010770:Phosphotransferases; C000717128:Reln protein, mouse; D012697:Serine Endopeptidases