title: Tbr2 expression in Cajal-Retzius cells and intermediate neuronal progenitors is required for morphogenesis of the dentate gyrus.
abstract: The dentate gyrus (DG) is a unique cortical region whose protracted development spans the embryonic and early postnatal periods. DG development involves large-scale reorganization of progenitor cell populations, ultimately leading to the establishment of the subgranular zone neurogenic niche. In the developing DG, the T-box transcription factor Tbr2 is expressed in both Cajal-Retzius cells derived from the cortical hem that guide migration of progenitors and neurons to the DG, and intermediate neuronal progenitors born in the dentate neuroepithelium that give rise to granule neurons. Here we show that in mice Tbr2 is required for proper migration of Cajal-Retzius cells to the DG; and, in the absence of Tbr2, formation of the hippocampal fissure is abnormal, leading to aberrant development of the transhilar radial glial scaffold and impaired migration of progenitors and neuroblasts to the developing DG. Furthermore, loss of Tbr2 results in decreased expression of Cxcr4 in migrating cells, leading to a premature burst of granule neurogenesis during early embryonic development accompanied by increased cell death in mutant animals. Formation of the transient subpial neurogenic zone was abnormal in Tbr2 conditional knock-outs, and the stem cell population in the DG was depleted before proper establishment of the subgranular zone. These studies indicate that Tbr2 is explicitly required for morphogenesis of the DG and participates in multiple aspects of the intricate developmental process of this structure.
authors: Department of Neurological Surgery, University of Washington, Seattle, Washington 98101, USA. rdhodge@uw.edu or rhevner@uw.edu
authors: Rebecca D
authors: RD
authors: Hodge
authors: Alfredo J
authors: AJ
authors: Garcia
authors: Gina E
authors: GE
authors: Elsen
authors: Branden R
authors: BR
authors: Nelson
authors: Kristin E
authors: KE
authors: Mussar
authors: Steven L
authors: SL
authors: Reiner
authors: Jan-Marino
authors: JM
authors: Ramirez
authors: Robert F
authors: RF
authors: Hevner
mesh_terms: D000367:Age Factors; D000704:Analysis of Variance; D000818:Animals; D000831:Animals, Newborn; D001973:Bromodeoxyuridine; D002454:Cell Differentiation / Q000235:genetics; D002540:Cerebral Cortex / Q000166:cytology / Q000196:embryology / Q000378:metabolism; D018891:Dentate Gyrus / Q000166:cytology* / Q000196:embryology; D004622:Embryo, Mammalian; D018507:Gene Expression Regulation, Developmental / Q000235:genetics*; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D018398:Homeodomain Proteins / Q000378:metabolism; D007381:Intermediate Filament Proteins / Q000235:genetics / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D009154:Mutation / Q000235:genetics; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000378:metabolism; D064231:Nestin; D058953:Neural Stem Cells / Q000378:metabolism*; D055495:Neurogenesis / Q000235:genetics; D009474:Neurons / Q000378:metabolism / Q000502:physiology*; D018809:Proliferating Cell Nuclear Antigen / Q000378:metabolism; D019718:Receptors, CXCR4 / Q000235:genetics / Q000378:metabolism; D011960:Receptors, Estrogen / Q000235:genetics / Q000378:metabolism; D020845:Selective Estrogen Receptor Modulators / Q000494:pharmacology; D055153:Stem Cell Niche / Q000502:physiology; D020825:T-Box Domain Proteins / Q000235:genetics / Q000378:metabolism*; D013629:Tamoxifen / Q000494:pharmacology; D025521:Tumor Suppressor Proteins / Q000378:metabolism; D000098551:Prospero-Related Homeobox 1 Protein
chemical_list: C514936:CXCR4 protein, mouse; C491198:Eomes protein, mouse; D018398:Homeodomain Proteins; D007381:Intermediate Filament Proteins; D009419:Nerve Tissue Proteins; C577485:Nes protein, mouse; D064231:Nestin; D018809:Proliferating Cell Nuclear Antigen; D019718:Receptors, CXCR4; D011960:Receptors, Estrogen; D020845:Selective Estrogen Receptor Modulators; D020825:T-Box Domain Proteins; D025521:Tumor Suppressor Proteins; D000098551:Prospero-Related Homeobox 1 Protein; D013629:Tamoxifen; D049452:Green Fluorescent Proteins; D001973:Bromodeoxyuridine