title: Cortical upper layer neurons derive from the subventricular zone as indicated by Svet1 gene expression.
abstract: The cerebral cortex is composed of a large variety of different neuron types. All cortical neurons, except some interneurons, are born in two proliferative zones, the cortical ventricular (VZ) and subventricular (SVZ) zones. The relative contribution of both proliferative zones to the generation of the diversity of the cortical neurons is not well understood. To further dissect the underlying mechanism, molecular markers specific for the SVZ are required. Towards this end we performed a subtraction of cDNA libraries, generated from E15.5 and E18.5 mouse cerebral cortex. A novel cDNA, Svet1, was cloned which was specifically expressed in the proliferating cells of the SVZ but not the VZ. The VZ is marked by the expression of the Otx1 gene. Later in development, Svet1 and Otx1 were expressed in subsets of cells of upper (II-IV) and deep (V-VI) layers, respectively. In the reeler cortex, where the layers are inverted, Svet1 and Otx1 label precursors of the upper and deeper layers, respectively, in their new location. Interestingly, in the Pax6/small eye mutant, Svet1 activity was abolished in the SVZ and in the upper part of the cortical plate while the Otx1 expression domain remained unchanged. Therefore, using Svet1 and Otx1 as cell-type-specific molecular markers for the upper and deep cortical layers we conclude that the Sey mutation affects predominantly the differentiation of the SVZ cells that fail to migrate into the cortical plate. The abnormality of the SVZ coincides with the absence of upper layer cells in the cortex. Taken together our data suggest that while the specification of deep cortical layers occurs in the ventricular zone, the SVZ is important for the proper specification of upper layers.
authors.affiliation: Department of Molecular Cell Biology, Max-Planck Institute for Biophysical Chemistry, 37077 Göttingen, Germany.
authors.forename: V
authors.initials: V
authors.lastname: Tarabykin
authors.forename: A
authors.initials: A
authors.lastname: Stoykova
authors.forename: N
authors.initials: N
authors.lastname: Usman
authors.forename: P
authors.initials: P
authors.lastname: Gruss
mesh_terms: D000818:Animals; D001483:Base Sequence; D015816:Cell Adhesion Molecules, Neuronal / Q000235:genetics; D002454:Cell Differentiation; D002540:Cerebral Cortex / Q000166:cytology* / Q000196:embryology / Q000378:metabolism; D003001:Cloning, Molecular; D018076:DNA, Complementary; D016326:Extracellular Matrix Proteins / Q000235:genetics; D015870:Gene Expression; D018398:Homeodomain Proteins / Q000235:genetics; D051379:Mice; D008810:Mice, Inbred C57BL; D008811:Mice, Inbred DBA; D008938:Mitosis; D008969:Molecular Sequence Data; D016296:Mutagenesis; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000378:metabolism* / Q000502:physiology*; D009474:Neurons / Q000166:cytology* / Q000378:metabolism; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism* / Q000502:physiology*; D009778:Occipital Lobe / Q000196:embryology; D051857:Otx Transcription Factors; D000091042:Reelin Protein; D012697:Serine Endopeptidases; D014157:Transcription Factors; D000099260:Empty Spiracles Homeobox Proteins
chemical_list: D015816:Cell Adhesion Molecules, Neuronal; D018076:DNA, Complementary; D016326:Extracellular Matrix Proteins; D018398:Homeodomain Proteins; D009419:Nerve Tissue Proteins; D009687:Nuclear Proteins; D051857:Otx Transcription Factors; D000091042:Reelin Protein; D012697:Serine Endopeptidases; D014157:Transcription Factors; D000099260:Empty Spiracles Homeobox Proteins; C497656:Otx1 protein, mouse