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Kozmik Z, Kozmikova I. Ancestral role of Pax6 in chordate brain regionalization. Front Cell Dev Biol 2024; 12:1431337. [PMID: 39119036 PMCID: PMC11306081 DOI: 10.3389/fcell.2024.1431337] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2024] [Accepted: 07/10/2024] [Indexed: 08/10/2024] Open
Abstract
The Pax6 gene is essential for eye and brain development across various animal species. Here, we investigate the function of Pax6 in the development of the anterior central nervous system (CNS) of the invertebrate chordate amphioxus using CRISPR/Cas9-induced genome editing. Specifically, we examined Pax6 mutants featuring a 6 bp deletion encompassing two invariant amino acids in the conserved paired domain, hypothesized to impair Pax6 DNA-binding capacity and gene regulatory functions. Although this mutation did not result in gross morphological changes in amphioxus larvae, it demonstrated a reduced ability to activate Pax6-responsive reporter gene, suggesting a hypomorphic effect. Expression analysis in mutant larvae revealed changes in gene expression within the anterior CNS, supporting the conserved role of Pax6 gene in brain regionalization across chordates. Additionally, our findings lend support to the hypothesis of a zona limitans intrathalamica (ZLI)-like region in amphioxus, suggesting evolutionary continuity in brain patterning mechanisms. ZLI region, found in both hemichordates and vertebrates, functions as a key signaling center and serves as a restrictive boundary between major thalamic regions.
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Affiliation(s)
| | - Iryna Kozmikova
- Laboratory of Transcriptional Regulation, Institute of Molecular Genetics of the Czech Academy of Sciences, Prague, Czechia
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2
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Wenzel DM, Olivier-Van Stichelen S. The O-GlcNAc cycling in neurodevelopment and associated diseases. Biochem Soc Trans 2022; 50:1693-1702. [PMID: 36383066 PMCID: PMC10462390 DOI: 10.1042/bst20220539] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2022] [Revised: 10/18/2022] [Accepted: 10/20/2022] [Indexed: 11/18/2022]
Abstract
Proper neuronal development is essential to growth and adult brain function. Alterations at any step of this highly organized sequence of events, due to genetic mutations or environmental factors, triggers brain malformations, which are leading causes of diseases including epilepsy, intellectual disabilities, and many others. The role of glycosylation in neuronal development has been emphasized for many years, notably in studying human congenital disorders of glycosylation (CDGs). These diseases highlight that genetic defects in glycosylation pathways are almost always associated with severe neurological abnormalities, suggesting that glycosylation plays an essential role in early brain development. Congenital disorders of O-GlcNAcylation are no exception, and all mutations of the O-GlcNAc transferase (OGT) are associated with X-linked intellectual disabilities (XLID). In addition, mouse models and in vitro mechanistic studies have reinforced the essential role of O-GlcNAcylation in neuronal development and signaling. In this review, we give an overview of the role of O-GlcNAcylation in this critical physiological process and emphasize the consequences of its dysregulation.
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Affiliation(s)
- Dawn M Wenzel
- Department of Biochemistry, Medical College of Wisconsin, Milwaukee, WI 53226, U.S.A
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3
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Leung RF, George AM, Roussel EM, Faux MC, Wigle JT, Eisenstat DD. Genetic Regulation of Vertebrate Forebrain Development by Homeobox Genes. Front Neurosci 2022; 16:843794. [PMID: 35546872 PMCID: PMC9081933 DOI: 10.3389/fnins.2022.843794] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2021] [Accepted: 03/14/2022] [Indexed: 01/19/2023] Open
Abstract
Forebrain development in vertebrates is regulated by transcription factors encoded by homeobox, bHLH and forkhead gene families throughout the progressive and overlapping stages of neural induction and patterning, regional specification and generation of neurons and glia from central nervous system (CNS) progenitor cells. Moreover, cell fate decisions, differentiation and migration of these committed CNS progenitors are controlled by the gene regulatory networks that are regulated by various homeodomain-containing transcription factors, including but not limited to those of the Pax (paired), Nkx, Otx (orthodenticle), Gsx/Gsh (genetic screened), and Dlx (distal-less) homeobox gene families. This comprehensive review outlines the integral role of key homeobox transcription factors and their target genes on forebrain development, focused primarily on the telencephalon. Furthermore, links of these transcription factors to human diseases, such as neurodevelopmental disorders and brain tumors are provided.
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Affiliation(s)
- Ryan F. Leung
- Murdoch Children’s Research Institute, The Royal Children’s Hospital Melbourne, Parkville, VIC, Australia
- Department of Paediatrics, University of Melbourne, Parkville, VIC, Australia
| | - Ankita M. George
- Murdoch Children’s Research Institute, The Royal Children’s Hospital Melbourne, Parkville, VIC, Australia
| | - Enola M. Roussel
- Murdoch Children’s Research Institute, The Royal Children’s Hospital Melbourne, Parkville, VIC, Australia
| | - Maree C. Faux
- Murdoch Children’s Research Institute, The Royal Children’s Hospital Melbourne, Parkville, VIC, Australia
- Department of Paediatrics, University of Melbourne, Parkville, VIC, Australia
- Department of Surgery, Royal Melbourne Hospital, The University of Melbourne, Parkville, VIC, Australia
| | - Jeffrey T. Wigle
- Department of Biochemistry and Medical Genetics, Max Rady College of Medicine, Rady Faculty of Health Sciences, University of Manitoba, Winnipeg, MB, Canada
- Institute of Cardiovascular Sciences, St. Boniface Hospital Albrechtsen Research Centre, Winnipeg, MB, Canada
| | - David D. Eisenstat
- Murdoch Children’s Research Institute, The Royal Children’s Hospital Melbourne, Parkville, VIC, Australia
- Department of Paediatrics, University of Melbourne, Parkville, VIC, Australia
- Department of Medical Genetics, University of Alberta, Edmonton, AB, Canada
- Department of Pediatrics, University of Alberta, Edmonton, AB, Canada
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4
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A Novel Mutation in Cse1l Disrupts Brain and Eye Development with Specific Effects on Pax6 Expression. J Dev Biol 2021; 9:jdb9030027. [PMID: 34287339 PMCID: PMC8293161 DOI: 10.3390/jdb9030027] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2021] [Revised: 06/21/2021] [Accepted: 07/01/2021] [Indexed: 12/23/2022] Open
Abstract
Forward genetics in the mouse continues to be a useful and unbiased approach to identifying new genes and alleles with previously unappreciated roles in mammalian development and disease. Here, we report a new mouse allele of Cse1l that was recovered from an ENU mutagenesis screen. Embryos homozygous for the anteater allele of Cse1l display a number of variable phenotypes, with craniofacial and ocular malformations being the most obvious. We provide evidence that Cse1l is the causal gene through complementation with a novel null allele of Cse1l generated by CRISPR-Cas9 editing. While the variability in the anteater phenotype was high enough to preclude a detailed molecular analysis, we demonstrate a very penetrant reduction in Pax6 levels in the developing eye along with significant ocular developmental phenotypes. The eye gene discovery tool iSyTE shows Cse1l to be significantly expressed in the lens from early eye development stages in embryos through adulthood. Cse1l has not previously been shown to be required for organogenesis as homozygosity for a null allele results in very early lethality. Future detailed studies of Cse1l function in craniofacial and neural development will be best served with a conditional allele to circumvent the variable phenotypes we report here. We suggest that human next-generation (whole genome or exome) sequencing studies yielding variants of unknown significance in CSE1L could consider these findings as part of variant analysis.
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Abstract
The mammalian cerebral cortex is the pinnacle of brain evolution, reaching its maximum complexity in terms of neuron number, diversity and functional circuitry. The emergence of this outstanding complexity begins during embryonic development, when a limited number of neural stem and progenitor cells manage to generate myriads of neurons in the appropriate numbers, types and proportions, in a process called neurogenesis. Here we review the current knowledge on the regulation of cortical neurogenesis, beginning with a description of the types of progenitor cells and their lineage relationships. This is followed by a review of the determinants of neuron fate, the molecular and genetic regulatory mechanisms, and considerations on the evolution of cortical neurogenesis in vertebrates leading to humans. We finish with an overview on how dysregulation of neurogenesis is a leading cause of human brain malformations and functional disabilities.
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Affiliation(s)
- Ana Villalba
- Instituto de Neurociencias, Consejo Superior de Investigaciones Científicas & Universidad Miguel Hernández, Sant Joan d'Alacant, Spain
| | - Magdalena Götz
- Institute for Stem Cell Research, Helmholtz Zentrum München & Biomedical Center, Ludwig-Maximilians Universitaet, Planegg-Martinsried, Germany
| | - Víctor Borrell
- Instituto de Neurociencias, Consejo Superior de Investigaciones Científicas & Universidad Miguel Hernández, Sant Joan d'Alacant, Spain.
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Gopinathan NV, Rajkumar S, Vasavada AR. A rare association of aniridia with conjunctival xerosis in two Indian siblings with PAX6 mutation. Indian J Ophthalmol 2020; 68:2635-2637. [PMID: 33120723 PMCID: PMC7774223 DOI: 10.4103/ijo.ijo_2185_20] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Affiliation(s)
- Nair Vidya Gopinathan
- Department of Pediatric Ophthalmology, Iladevi Cataract and IOL Research Centre, Ahmedabad, Gujarat, India
| | - Sankaranarayanan Rajkumar
- Department of Pediatric Ophthalmology, Iladevi Cataract and IOL Research Centre, Ahmedabad, Gujarat; Department of Ophthalmic Genetics, Aditya Jyot Foundation for Twinkling Little Eyes, Mumbai, Maharashtra, India
| | - Abhay Raghukant Vasavada
- Department of Pediatric Ophthalmology, Iladevi Cataract and IOL Research Centre, Ahmedabad, Gujarat, India
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Jeon K, Kumar D, Conway AE, Park K, Jothi R, Jetten AM. GLIS3 Transcriptionally Activates WNT Genes to Promote Differentiation of Human Embryonic Stem Cells into Posterior Neural Progenitors. Stem Cells 2018; 37:202-215. [PMID: 30376208 DOI: 10.1002/stem.2941] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2018] [Revised: 09/27/2018] [Accepted: 10/09/2018] [Indexed: 12/11/2022]
Abstract
Anterior-posterior (A-P) specification of the neural tube involves initial acquisition of anterior fate followed by the induction of posterior characteristics in the primitive anterior neuroectoderm. Several morphogens have been implicated in the regulation of A-P neural patterning; however, our understanding of the upstream regulators of these morphogens remains incomplete. Here, we show that the Krüppel-like zinc finger transcription factor GLI-Similar 3 (GLIS3) can direct differentiation of human embryonic stem cells (hESCs) into posterior neural progenitor cells in lieu of the default anterior pathway. Transcriptomic analyses reveal that this switch in cell fate is due to rapid activation of Wingless/Integrated (WNT) signaling pathway. Mechanistically, through genome-wide RNA-Seq, ChIP-Seq, and functional analyses, we show that GLIS3 binds to and directly regulates the transcription of several WNT genes, including the strong posteriorizing factor WNT3A, and that inhibition of WNT signaling is sufficient to abrogate GLIS3-induced posterior specification. Our findings suggest a potential role for GLIS3 in the regulation of A-P specification through direct transcriptional activation of WNT genes. Stem Cells 2018 Stem Cells 2019;37:202-215.
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Affiliation(s)
- Kilsoo Jeon
- Immunity, Inflammation and Disease Laboratory, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, North Carolina, USA
| | - Dhirendra Kumar
- Epigenetics & Stem Cell Biology Laboratory, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, North Carolina, USA
| | - Amanda E Conway
- Epigenetics & Stem Cell Biology Laboratory, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, North Carolina, USA
| | - Kyeyoon Park
- NIH Stem Cell Unit, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland, USA
| | - Raja Jothi
- Epigenetics & Stem Cell Biology Laboratory, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, North Carolina, USA
| | - Anton M Jetten
- Immunity, Inflammation and Disease Laboratory, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, North Carolina, USA
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Zic4-Lineage Cells Increase Their Contribution to Visual Thalamic Nuclei during Murine Embryogenesis If They Are Homozygous or Heterozygous for Loss of Pax6 Function. eNeuro 2018; 5:eN-CFN-0367-18. [PMID: 30406191 PMCID: PMC6220585 DOI: 10.1523/eneuro.0367-18.2018] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2018] [Accepted: 09/22/2018] [Indexed: 12/22/2022] Open
Abstract
Our aim was to study the mechanisms that contribute to the development of discrete thalamic nuclei during mouse embryogenesis (both sexes included). We characterized the expression of the transcription factor coding gene Zic4 and the distribution of cells that expressed Zic4 in their lineage. We used genetic fate mapping to show that Zic4-lineage cells mainly contribute to a subset of thalamic nuclei, in particular the lateral geniculate nuclei (LGNs), which are crucial components of the visual pathway. We observed that almost all Zic4-lineage diencephalic progenitors express the transcription factor Pax6 at variable location-dependent levels. We used conditional mutagenesis to delete either one or both copies of Pax6 from Zic4-lineage cells. We found that Zic4-lineage cells carrying either homozygous or heterozygous loss of Pax6 contributed in abnormally high numbers to one or both of the main lateral geniculate nuclei (LGNs). This could not be attributed to a change in cell production and was likely due to altered sorting of thalamic cells. Our results indicate that positional information encoded by the levels of Pax6 in diencephalic progenitors is an important determinant of the eventual locations of their daughter cells.
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Baker LR, Weasner BM, Nagel A, Neuman SD, Bashirullah A, Kumar JP. Eyeless/Pax6 initiates eye formation non-autonomously from the peripodial epithelium. Development 2018; 145:dev.163329. [PMID: 29980566 DOI: 10.1242/dev.163329] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2018] [Accepted: 06/27/2018] [Indexed: 01/08/2023]
Abstract
The transcription factor Pax6 is considered the master control gene for eye formation because (1) it is present within the genomes and retina/lens of all animals with a visual system; (2) severe retinal defects accompany its loss; (3) Pax6 genes have the ability to substitute for one another across the animal kingdom; and (4) Pax6 genes are capable of inducing ectopic eye/lens in flies and mammals. Many roles of Pax6 were first elucidated in Drosophila through studies of the gene eyeless (ey), which controls both growth of the entire eye-antennal imaginal disc and fate specification of the eye. We show that Ey also plays a surprising role within cells of the peripodial epithelium to control pattern formation. It regulates the expression of decapentaplegic (dpp), which is required for initiation of the morphogenetic furrow in the eye itself. Loss of Ey within the peripodial epithelium leads to the loss of dpp expression within the eye, failure of the furrow to initiate, and abrogation of retinal development. These findings reveal an unexpected mechanism for how Pax6 controls eye development in Drosophila.
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Affiliation(s)
- Luke R Baker
- Department of Biology, Indiana University, Bloomington, IN 47405, USA
| | - Bonnie M Weasner
- Department of Biology, Indiana University, Bloomington, IN 47405, USA
| | - Athena Nagel
- Department of Biology, Indiana University, Bloomington, IN 47405, USA
| | - Sarah D Neuman
- Department of Pharmaceutical Sciences, University of Wisconsin, Madison, WI 53705, USA
| | - Arash Bashirullah
- Department of Pharmaceutical Sciences, University of Wisconsin, Madison, WI 53705, USA
| | - Justin P Kumar
- Department of Biology, Indiana University, Bloomington, IN 47405, USA
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10
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Genetics and mechanisms leading to human cortical malformations. Semin Cell Dev Biol 2018; 76:33-75. [DOI: 10.1016/j.semcdb.2017.09.031] [Citation(s) in RCA: 74] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2017] [Revised: 09/21/2017] [Accepted: 09/21/2017] [Indexed: 02/06/2023]
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11
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A Novel and Multivalent Role of Pax6 in Cerebellar Development. J Neurosci 2017; 36:9057-69. [PMID: 27581449 DOI: 10.1523/jneurosci.4385-15.2016] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2015] [Accepted: 07/12/2016] [Indexed: 11/21/2022] Open
Abstract
UNLABELLED Pax6 is a prominent gene in brain development. The deletion of Pax6 results in devastated development of eye, olfactory bulb, and cortex. However, it has been reported that the Pax6-null Sey cerebellum only has minor defects involving granule cells despite Pax6 being expressed throughout cerebellar development. The present work has uncovered a requirement of Pax6 in the development of all rhombic lip (RL) lineages. A significant downregulation of Tbr1 and Tbr2 expression is found in the Sey cerebellum, these are cell-specific markers of cerebellar nuclear (CN) neurons and unipolar brush cells (UBCs), respectively. The examination of Tbr1 and Lmx1a immunolabeling and Nissl staining confirmed the loss of CN neurons from the Sey cerebellum. CN neuron progenitors are produced in the mutant but there is an enhanced death of these neurons as shown by increased presence of caspase-3-positive cells. These data indicate that Pax6 regulates the survival of CN neuron progenitors. Furthermore, the analysis of experimental mouse chimeras suggests a cell-extrinsic role of Pax6 in CN neuron survival. For UBCs, using Tbr2 immunolabeling, these cells are significantly reduced in the Sey cerebellum. The loss of UBCs in the mutant is due partly to cell death in the RL and also to the reduced production of progenitors from the RL. These results demonstrate a critical role for Pax6 in regulating the generation and survival of UBCs. This and previous work from our laboratory demonstrate a seminal role of Pax6 in the development of all cerebellar glutamatergic neurons. SIGNIFICANCE STATEMENT Pax6 is a key molecule in development. Pax6 is best known as the master control gene in eye development with mutations causing aniridia in humans. Pax6 also plays important developmental roles in the cortex and olfactory bulb. During cerebellar development, Pax6 is robustly expressed in the germinal zone of all glutamatergic neurons [cerebellar nuclear (CN) neurons, granule cells, and unipolar brush cells (UBCs)]. Past work has not found abnormalities in the CN and UBC populations. Our study reveals that the Pax6-null mutation dramatically affects these cells and identifies Pax6 as a key regulator of cell survival in CN neurons and of cell production in UBCs. The present study shows how Pax6 is key to the development of glutamatergic cells in the cerebellum.
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Parish EV, Mason JO, Price DJ. Expression of Barhl2 and its relationship with Pax6 expression in the forebrain of the mouse embryo. BMC Neurosci 2016; 17:76. [PMID: 27887593 PMCID: PMC5124293 DOI: 10.1186/s12868-016-0311-6] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2016] [Accepted: 11/16/2016] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The transcription factor Barhl2 is an antiproneural transcription factor with roles in neuronal differentiation. The functions of its homologue in Drosophila development are better understood than its functions in mammalian brain development. Existing evidence suggests that its expression in the embryonic forebrain of the mouse is regional and may complement that of another transcription factor that is important for forebrain development, Pax6. The aim of this study is to provide a more detailed description of the Barhl2 expression pattern in the embryonic forebrain than is currently available, to relate its expression domains to those of Pax6 and to examine the effects of Pax6 loss on Barhl2 expression. RESULTS We found that Barhl2 is expressed in the developing diencephalon from the time of anterior neural tube closure. Its expression initially overlaps that of Pax6 in a central region of the alar diencephalon but over the following days their domains of expression become complementary in most forebrain regions. The exceptions are the thalamus and pretectum, where countergradients of Pax6 and Barhl2 expression are established by embryonic day 12.5, before overall Pax6 levels in these regions decline greatly while Barhl2 levels remain relatively high. We found that Barhl2 expression becomes upregulated in specifically the thalamus and pretectum in Pax6-null mice. CONCLUSIONS The region-specific expression pattern of Barhl2 makes it likely to be an important player in the development of region-specific differences in embryonic mouse forebrain. Repression of its expression in the thalamus and pretectum by Pax6 may be crucial for allowing proneural factors to promote normal neuronal differentiation in this region.
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Affiliation(s)
- Elisa V Parish
- Centre for Integrative Physiology, The University of Edinburgh, Hugh Robson Building, Edinburgh, EH8 9XD, UK
| | - John O Mason
- Centre for Integrative Physiology, The University of Edinburgh, Hugh Robson Building, Edinburgh, EH8 9XD, UK
| | - David J Price
- Centre for Integrative Physiology, The University of Edinburgh, Hugh Robson Building, Edinburgh, EH8 9XD, UK.
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Hiraoka K, Sumiyoshi A, Nonaka H, Kikkawa T, Kawashima R, Osumi N. Regional Volume Decreases in the Brain of Pax6 Heterozygous Mutant Rats: MRI Deformation-Based Morphometry. PLoS One 2016; 11:e0158153. [PMID: 27355350 PMCID: PMC4927189 DOI: 10.1371/journal.pone.0158153] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2016] [Accepted: 06/10/2016] [Indexed: 11/18/2022] Open
Abstract
Pax6 is a transcription factor that pleiotropically regulates various developmental processes in the central nervous system. In a previous study, we revealed that Pax6 heterozygous mutant (rSey2/+) adult rats exhibit abnormalities in social interaction. However, the brain malformations underlying the behavioral abnormality are unknown. To elucidate the brain malformations in rSey2/+ rats, we morphometrically analyzed brains of rSey2/+ and wild type rats using small-animal magnetic resonance imaging (MRI). Sixty 10-week-old rats underwent brain MRI (29 rSey2/+ rats and 31 wild type rats). SPM8 software was used for image preprocessing and statistical image analysis. Normalized maps of the Jacobian determinant, a parameter for the expansion and/or contraction of brain regions, were obtained for each rat. rSey2/+ rats showed significant volume decreases in various brain regions including the neocortex, corpus callosum, olfactory structures, hippocampal formation, diencephalon, and midbrain compared to wild type rats. Among brain regions, the anterior commissure showed significant interaction between genotype and sex, indicating the effect of genotype difference on the anterior commissure volume was more robust in females than in males. The rSey2/+ rats exhibited decreased volume in various gray and white matter regions of the brain, which may contribute to manifestation of abnormal social behaviors.
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Affiliation(s)
- Kotaro Hiraoka
- Division of Cyclotron Nuclear Medicine, Cyclotron and Radioisotope Center, Tohoku University, Sendai, Japan
- * E-mail:
| | - Akira Sumiyoshi
- Department of Functional Brain Imaging, Institute of Development, Aging and Cancer, Tohoku University, Sendai, Japan
| | - Hiroi Nonaka
- Department of Functional Brain Imaging, Institute of Development, Aging and Cancer, Tohoku University, Sendai, Japan
| | - Takako Kikkawa
- Department of Developmental Neuroscience, Center for Translational and Advanced Animal Research, Tohoku University Graduate School of Medicine, Sendai, Japan
| | - Ryuta Kawashima
- Department of Functional Brain Imaging, Institute of Development, Aging and Cancer, Tohoku University, Sendai, Japan
| | - Noriko Osumi
- Department of Developmental Neuroscience, Center for Translational and Advanced Animal Research, Tohoku University Graduate School of Medicine, Sendai, Japan
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Analysis of compound heterozygotes reveals that the mouse floxed Pax6 (tm1Ued) allele produces abnormal eye phenotypes. Transgenic Res 2016; 25:679-92. [PMID: 27240603 PMCID: PMC5023747 DOI: 10.1007/s11248-016-9962-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2015] [Accepted: 05/13/2016] [Indexed: 01/27/2023]
Abstract
Analysis of abnormal phenotypes produced by different types of mutations has been crucial for our understanding of gene function. Some floxed alleles that retain a neomycin-resistance selection cassette (neo cassette) are not equivalent to wild-type alleles and provide useful experimental resources. Pax6 is an important developmental gene and the aim of this study was to determine whether the floxed Pax6tm1Ued (Pax6fl) allele, which has a retained neo cassette, produced any abnormal eye phenotypes that would imply that it differs from the wild-type allele. Homozygous Pax6fl/fl and heterozygous Pax6fl/+ mice had no overt qualitative eye abnormalities but morphometric analysis showed that Pax6fl/fl corneas tended be thicker and smaller in diameter. To aid identification of weak effects, we produced compound heterozygotes with the Pax6Sey-Neu (Pax6−) null allele. Pax6fl/− compound heterozygotes had more severe eye abnormalities than Pax6+/− heterozygotes, implying that Pax6fl differs from the wild-type Pax6+ allele. Immunohistochemistry showed that the Pax6fl/− corneal epithelium was positive for keratin 19 and negative for keratin 12, indicating that it was abnormally differentiated. This Pax6fl allele provides a useful addition to the existing Pax6 allelic series and this study demonstrates the utility of using compound heterozygotes with null alleles to unmask cryptic effects of floxed alleles.
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15
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Suzuki T, Takayama R, Sato M. eyeless/Pax6 controls the production of glial cells in the visual center of Drosophila melanogaster. Dev Biol 2015; 409:343-53. [PMID: 26670857 DOI: 10.1016/j.ydbio.2015.12.004] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2015] [Revised: 11/11/2015] [Accepted: 12/04/2015] [Indexed: 10/22/2022]
Abstract
Pax6 is known as a neurogenic factor in the development of the central nervous system and regulates proliferation of neuronal progenitor cells and promotes neuronal differentiation. In addition to neurogenesis, Pax6 is also involved in the specification and maturation of glial cells. Here, we show that Eyeless (Ey), Drosophila homolog of Pax6, regulates the production of glial cells in the brain. In the developing fly visual center, the production of neurons and glial cells are controlled by the temporal transcription factors that are sequentially expressed in neuroblasts (NBs). Among them, NBs of the last temporal window produce astrocyte-like glial cells. Ey is strongly expressed in the middle aged NBs, whose temporal window is earlier compared with glia producing older NBs. Weak Ey expression is also detected in the glia producing NBs. Our results suggest that Ey expression in the middle aged NBs indirectly control gliogenesis from the oldest NBs by regulating other temporal transcription factors. Additionally, weak Ey expression in the NBs of last temporal window may directly control gliogenesis. Ey is also expressed in neurons produced from the NBs of Ey-positive temporal window. Interestingly, neuron-specific overexpression of Ey causes significant increase in glial cells suggesting that neuronal expression of Ey may also contribute to gliogenesis. Thus, Pax6-dependent regulation of astrocyte-like glial development is conserved throughout the animal kingdom.
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Affiliation(s)
- Takumi Suzuki
- Laboratory of Developmental Neurobiology, Brain/Liver Interface Medicine Research Center, Kanazawa University, 13-1 Takaramachi Kanazawa-shi, Ishikawa 920-8640, Japan
| | - Rie Takayama
- Laboratory of Developmental Neurobiology, Brain/Liver Interface Medicine Research Center, Kanazawa University, 13-1 Takaramachi Kanazawa-shi, Ishikawa 920-8640, Japan; CREST, JST, 4-1-8 Honcho Kawaguchi, Saitama 332-0012, Japan
| | - Makoto Sato
- Laboratory of Developmental Neurobiology, Brain/Liver Interface Medicine Research Center, Kanazawa University, 13-1 Takaramachi Kanazawa-shi, Ishikawa 920-8640, Japan; Graduate School of Medical Sciences, Kanazawa University, 13-1 Takaramachi Kanazawa-shi, Ishikawa 920-8640, Japan; CREST, JST, 4-1-8 Honcho Kawaguchi, Saitama 332-0012, Japan.
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Clegg JM, Li Z, Molinek M, Caballero IM, Manuel MN, Price DJ. Pax6 is required intrinsically by thalamic progenitors for the normal molecular patterning of thalamic neurons but not the growth and guidance of their axons. Neural Dev 2015; 10:26. [PMID: 26520399 PMCID: PMC4628245 DOI: 10.1186/s13064-015-0053-7] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2015] [Accepted: 10/23/2015] [Indexed: 11/16/2022] Open
Abstract
BACKGROUND In mouse embryos, the Pax6 transcription factor is expressed in the progenitors of thalamic neurons but not in thalamic neurons themselves. Its null-mutation causes early mis-patterning of thalamic progenitors. It is known that thalamic neurons generated by Pax6 (-/-) progenitors do not develop their normal connections with the cortex, but it is not clear why. We investigated the extent to which defects intrinsic to the thalamus are responsible. RESULTS We first confirmed that, in constitutive Pax6 (-/-) mutants, the axons of thalamic neurons fail to enter the telencephalon and, instead, many of them take an abnormal path to the hypothalamus, whose expression of Slits would normally repel them. We found that thalamic neurons show reduced expression of the Slit receptor Robo2 in Pax6 (-/-) mutants, which might enhance the ability of their axons to enter the hypothalamus. Remarkably, however, in chimeras comprising a mixture of Pax6 (-/-) and Pax6 (+/+) cells, Pax6 (-/-) thalamic neurons are able to generate axons that exit the diencephalon, take normal trajectories through the telencephalon and avoid the hypothalamus. This occurs despite abnormalities in their molecular patterning (they express Nkx2.2, unlike normal thalamic neurons) and their reduced expression of Robo2. In conditional mutants, acute deletion of Pax6 from the forebrain at the time when thalamic axons are starting to grow does not prevent the development of the thalamocortical tract, suggesting that earlier extra-thalamic patterning and /or morphological defects are the main cause of thalamocortical tract failure in Pax6 (-/-) constitutive mutants. CONCLUSIONS Our results indicate that Pax6 is required by thalamic progenitors for the normal molecular patterning of the thalamic neurons that they generate but thalamic neurons do not need normal Pax6-dependent patterning to become competent to grow axons that can be guided appropriately.
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Affiliation(s)
- James M Clegg
- Centre for Integrative Physiology, University of Edinburgh, Hugh Robson Building, George Square, Edinburgh, EH8 9XD, UK.
| | - Ziwen Li
- Centre for Integrative Physiology, University of Edinburgh, Hugh Robson Building, George Square, Edinburgh, EH8 9XD, UK.
| | - Michael Molinek
- Centre for Integrative Physiology, University of Edinburgh, Hugh Robson Building, George Square, Edinburgh, EH8 9XD, UK.
| | - Isabel Martín Caballero
- Centre for Integrative Physiology, University of Edinburgh, Hugh Robson Building, George Square, Edinburgh, EH8 9XD, UK.
- Current address: Laboratory of Molecular Neurobiology, Karolinska Institute, 17177, Scheeles Väg 1, Sweden.
| | - Martine N Manuel
- Centre for Integrative Physiology, University of Edinburgh, Hugh Robson Building, George Square, Edinburgh, EH8 9XD, UK.
| | - David J Price
- Centre for Integrative Physiology, University of Edinburgh, Hugh Robson Building, George Square, Edinburgh, EH8 9XD, UK.
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Ypsilanti AR, Rubenstein JLR. Transcriptional and epigenetic mechanisms of early cortical development: An examination of how Pax6 coordinates cortical development. J Comp Neurol 2015; 524:609-29. [PMID: 26304102 DOI: 10.1002/cne.23866] [Citation(s) in RCA: 48] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2015] [Revised: 07/14/2015] [Accepted: 07/17/2015] [Indexed: 12/26/2022]
Abstract
The development of the cortex is an elaborate process that integrates a plethora of finely tuned molecular processes ranging from carefully regulated gradients of transcription factors, dynamic changes in the chromatin landscape, or formation of protein complexes to elicit and regulate transcription. Combined with cellular processes such as cell type specification, proliferation, differentiation, and migration, all of these developmental processes result in the establishment of an adult mammalian cortex with its typical lamination and regional patterning. By examining in-depth the role of one transcription factor, Pax6, on the regulation of cortical development, its integration in the regulation of chromatin state, and its regulation by cis-regulatory elements, we aim to demonstrate the importance of integrating each level of regulation in our understanding of cortical development.
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Affiliation(s)
- Athéna R Ypsilanti
- Department of Psychiatry, Neuroscience Program, and the Nina Ireland Laboratory of Developmental Neurobiology, University of California, San Francisco, San Francisco, California
| | - John L R Rubenstein
- Department of Psychiatry, Neuroscience Program, and the Nina Ireland Laboratory of Developmental Neurobiology, University of California, San Francisco, San Francisco, California
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Altenhein B, Cattenoz PB, Giangrande A. The early life of a fly glial cell. WILEY INTERDISCIPLINARY REVIEWS-DEVELOPMENTAL BIOLOGY 2015. [DOI: 10.1002/wdev.200] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Affiliation(s)
| | | | - Angela Giangrande
- Department of Functional Genomics and Cancer; IGBMC; Illkirch France
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19
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Tylkowski MA, Yang K, Hoyer-Fender S, Stoykova A. Pax6 controls centriole maturation in cortical progenitors through Odf2. Cell Mol Life Sci 2015; 72:1795-809. [PMID: 25352170 PMCID: PMC11114037 DOI: 10.1007/s00018-014-1766-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2014] [Revised: 10/14/2014] [Accepted: 10/17/2014] [Indexed: 12/11/2022]
Abstract
Cortical glutamatergic neurons are generated by radial glial cells (RGCs), specified by the expression of transcription factor (TF) Pax6, in the germinative zones of the dorsal telencephalon. Here, we demonstrate that Pax6 regulates the structural assembly of the interphase centrosomes. In the cortex of the Pax6-deficient Small eye (Sey/Sey) mutant, we find a defect of the appendages of the mother centrioles, indicating incomplete centrosome maturation. Consequently, RGCs fail to generate primary cilia, and instead of staying in the germinative zone for renewal, RGCs detach from the ventricular surface thus affecting the interkinetic nuclear migration and they exit prematurely from mitosis. Mechanistically, we show that TF Pax6 directly regulates the activity of the Odf2 gene encoding for the appendage-specific protein Odf2 with a role for the assembly of mother centriole. Our findings demonstrate a molecular mechanism that explains important characteristics of the centrosome disassembly and malfunctioning in developing cortex lacking Pax6.
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Affiliation(s)
- Marco A. Tylkowski
- Research Group of Molecular Developmental Neurobiology, Department Molecular Cell Biology, Max-Planck Institute for Biophysical Chemistry, Am Faßberg 11, 37077 Göttingen, Germany
- Center for Nanoscale Microscopy and Molecular Physiology of the Brain (CNMPB), 37075 Göttingen, Germany
| | - Kefei Yang
- Johann-Friedrich-Blumenbach-Institute of Zoology and Anthropology, Developmental Biology, GZMB, Ernst-Caspari-Haus, Georg-August-Universität Göttingen, Justus-von-Liebig-Weg 11, Göttingen, Germany
| | - Sigrid Hoyer-Fender
- Johann-Friedrich-Blumenbach-Institute of Zoology and Anthropology, Developmental Biology, GZMB, Ernst-Caspari-Haus, Georg-August-Universität Göttingen, Justus-von-Liebig-Weg 11, Göttingen, Germany
| | - Anastassia Stoykova
- Research Group of Molecular Developmental Neurobiology, Department Molecular Cell Biology, Max-Planck Institute for Biophysical Chemistry, Am Faßberg 11, 37077 Göttingen, Germany
- Center for Nanoscale Microscopy and Molecular Physiology of the Brain (CNMPB), 37075 Göttingen, Germany
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20
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Manuel MN, Mi D, Mason JO, Price DJ. Regulation of cerebral cortical neurogenesis by the Pax6 transcription factor. Front Cell Neurosci 2015; 9:70. [PMID: 25805971 PMCID: PMC4354436 DOI: 10.3389/fncel.2015.00070] [Citation(s) in RCA: 100] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2014] [Accepted: 02/18/2015] [Indexed: 12/19/2022] Open
Abstract
Understanding brain development remains a major challenge at the heart of understanding what makes us human. The neocortex, in evolutionary terms the newest part of the cerebral cortex, is the seat of higher cognitive functions. Its normal development requires the production, positioning, and appropriate interconnection of very large numbers of both excitatory and inhibitory neurons. Pax6 is one of a relatively small group of transcription factors that exert high-level control of cortical development, and whose mutation or deletion from developing embryos causes major brain defects and a wide range of neurodevelopmental disorders. Pax6 is very highly conserved between primate and non-primate species, is expressed in a gradient throughout the developing cortex and is essential for normal corticogenesis. Our understanding of Pax6’s functions and the cellular processes that it regulates during mammalian cortical development has significantly advanced in the last decade, owing to the combined application of genetic and biochemical analyses. Here, we review the functional importance of Pax6 in regulating cortical progenitor proliferation, neurogenesis, and formation of cortical layers and highlight important differences between rodents and primates. We also review the pathological effects of PAX6 mutations in human neurodevelopmental disorders. We discuss some aspects of Pax6’s molecular actions including its own complex transcriptional regulation, the distinct molecular functions of its splice variants and some of Pax6’s known direct targets which mediate its actions during cortical development.
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Affiliation(s)
- Martine N Manuel
- Centre for Integrative Physiology, The University of Edinburgh, Edinburgh UK
| | - Da Mi
- Centre for Integrative Physiology, The University of Edinburgh, Edinburgh UK
| | - John O Mason
- Centre for Integrative Physiology, The University of Edinburgh, Edinburgh UK
| | - David J Price
- Centre for Integrative Physiology, The University of Edinburgh, Edinburgh UK
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21
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Science and Art of Cell-Based Ocular Surface Regeneration. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2015; 319:45-106. [DOI: 10.1016/bs.ircmb.2015.07.001] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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Anatomical, molecular and pathological consideration of the circumventricular organs. Neurochirurgie 2014; 61:90-100. [PMID: 24974365 DOI: 10.1016/j.neuchi.2013.04.006] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2013] [Revised: 04/15/2013] [Accepted: 04/23/2013] [Indexed: 01/25/2023]
Abstract
BACKGROUND AND PURPOSE Circumventricular organs (CVOs) are a diverse group of specialised structures characterized by peculiar vascular and position around the third and fourth ventricles of the brain. In humans, these organs are present during the fetal period and some become vestigial after birth. Some, such as the pineal gland (PG), subcommissural organ (SCO) and organum vasculosum of the lamina terminalis (OVLT), which are located around the third ventricle, might be the site of origin of periventricular tumours. In contrast to humans, CVOs are present in the adult rat and can be dissected by laser capture microdissection (LCM). METHODS In this study, we used LCM and microarrays to analyse the transcriptomes of three CVOs, the SCO, the subfornical organ (SFO) and the PG and the third ventricle ependyma of the adult rat, in order to better characterise these organs at the molecular level. Furthermore, an immunohistochemical study of Claudin-3 (CLDN3), a membrane protein involved in forming cellular tight junctions, was performed at the level of the SCO. RESULTS This study highlighted some potentially new or already described specific markers of these structures as Erbb2 and Col11a1 in ependyma, Epcam and CLDN3 in the SCO, Ren1 and Slc22a3 in the SFO and Tph, Anat and Asmt in the PG. Moreover, we found that CLDN3 expression was restricted to the apical pole of ependymocytes in the SCO.
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23
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Walcher T, Xie Q, Sun J, Irmler M, Beckers J, Öztürk T, Niessing D, Stoykova A, Cvekl A, Ninkovic J, Götz M. Functional dissection of the paired domain of Pax6 reveals molecular mechanisms of coordinating neurogenesis and proliferation. Development 2013; 140:1123-36. [PMID: 23404109 DOI: 10.1242/dev.082875] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
To achieve adequate organ development and size, cell proliferation and differentiation have to be tightly regulated and coordinated. The transcription factor Pax6 regulates patterning, neurogenesis and proliferation in forebrain development. The molecular basis of this regulation is not well understood. As the bipartite DNA-binding paired domain of Pax6 regulates forebrain development, we examined mice with point mutations in its individual DNA-binding subdomains PAI (Pax6(Leca4), N50K) and RED (Pax6(Leca2), R128C). This revealed distinct roles in regulating proliferation in the developing cerebral cortex, with the PAI and RED subdomain mutations reducing and increasing, respectively, the number of mitoses. Conversely, neurogenesis was affected only by the PAI subdomain mutation, phenocopying the neurogenic defects observed in full Pax6 mutants. Genome-wide expression profiling identified molecularly discrete signatures of Pax6(Leca4) and Pax6(Leca2) mutations. Comparison to Pax6 targets identified by chromatin immunoprecipitation led to the identification and functional characterization of distinct DNA motifs in the promoters of target genes dysregulated in the Pax6(Leca2) or Pax6(Leca4) mutants, further supporting the distinct regulatory functions of the DNA-binding subdomains. Thus, Pax6 achieves its key roles in the developing forebrain by utilizing particular subdomains to coordinate patterning, neurogenesis and proliferation simultaneously.
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Affiliation(s)
- Tessa Walcher
- Institute of Stem Cell Research, Helmholtz Center Munich, 85764 Neuherberg-Munich, Germany
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24
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Carbe C, Garg A, Cai Z, Li H, Powers A, Zhang X. An allelic series at the paired box gene 6 (Pax6) locus reveals the functional specificity of Pax genes. J Biol Chem 2013; 288:12130-41. [PMID: 23515312 DOI: 10.1074/jbc.m112.436865] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The advent of the ocular and nervous system in metazoan evolution coincides with the diversification of a single ancestral paired box (Pax) gene into Pax6, Pax6(5a), and Pax2. To investigate the role of these Pax genes in neural development, we have generated an allelic series of knock-in models at the Pax6 locus. We showed that although Pax6(5a) and Pax2 could not replace Pax6 for its autoregulation in lens induction or for neural differentiation in retina, Pax6(5a) was sufficient for corneal-lenticular detachment. In brain development, cell proliferation in the cerebral cortex and dorsoventral patterning of the telencephalon and neural tube were partially rescued in either knock-in mutant. Contrary to the previous belief, our genetic studies showed that the Pax6 isoform Pax6(5a) could potentially play a role in neuronal differentiation in brain development. Importantly, Pax2 showed greater rescue efficiency than Pax6(5a) in the telencephalon even though the latter was identical to Pax6 outside the paired domain. In studying Ngn2, a Pax6 direct target gene in telencephalon, we showed that the level of Ngn2 expression correlated with the in vitro binding of Pax2, Pax6, and Pax6(5a) paired domain on its enhancer. Our results show that Pax6 is uniquely required for eye development, but in brain development, Pax6 can be functionally substituted by related Pax family genes that share a similar paired domain binding specificity.
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Affiliation(s)
- Christian Carbe
- Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis, Indiana 46202, USA
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25
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Abstract
The discovery in the year 2000 that radial glial cells act as neural stem and progenitor cells in development has led to a change in the concept of neural stem cells in the adult brain. Not only are adult stem cells in the neurogenic niches glial in nature, but also glial cells outside these niches display greater potential when reacting to brain injury. Thus, a concept that emerged from developmental studies may hold the clue for neural repair.
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Affiliation(s)
- Paolo Malatesta
- IRCCS-AOU San Martino-IST, Largo Rosanna Benzi 10, 16132, Genoa- Italy.
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26
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Chacon MA, Boulanger LM. MHC class I protein is expressed by neurons and neural progenitors in mid-gestation mouse brain. Mol Cell Neurosci 2012; 52:117-27. [PMID: 23147111 DOI: 10.1016/j.mcn.2012.11.004] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2012] [Revised: 10/09/2012] [Accepted: 11/02/2012] [Indexed: 02/04/2023] Open
Abstract
Proteins of the major histocompatibility complex class I (MHCI) are known for their role in the vertebrate adaptive immune response, and are required for normal postnatal brain development and plasticity. However, it remains unknown if MHCI proteins are present in the mammalian brain before birth. Here, we show that MHCI proteins are widely expressed in the developing mouse central nervous system at mid-gestation (E9.5-10.5). MHCI is strongly expressed in several regions of the prenatal brain, including the neuroepithelium and olfactory placode. MHCI is expressed by neural progenitors at these ages, as identified by co-expression in cells positive for neuron-specific class III β-tubulin (Tuj1) or for Pax6, a marker of neural progenitors in the dorsal neuroepithelium. MHCI is also co-expressed with nestin, a marker of neural stem/progenitor cells, in olfactory placode, but the co-localization is less extensive in other regions. MHCI is detected in the small population of post-mitotic neurons that are present at this early stage of brain development, as identified by co-expression in cells positive for neuronal microtubule-associated protein-2 (MAP2). Thus MHCI protein is expressed during the earliest stages of neuronal differentiation in the mammalian brain. MHCI expression in neurons and neural progenitors at mid-gestation, prior to the maturation of the adaptive immune system, is consistent with MHCI performing non-immune functions in prenatal brain development. These results raise the possibility that disruption of the levels and/or patterns of MHCI expression in the prenatal brain could contribute to the pathogenesis of neurodevelopmental disorders.
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Affiliation(s)
- Marcelo A Chacon
- Department of Molecular Biology and Princeton Neuroscience Institute, Princeton University, 123 Lewis Thomas Laboratories, Washington Road, Princeton, NJ 08544, USA
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Grondona JM, Hoyo-Becerra C, Visser R, Fernández-Llebrez P, López-Ávalos MD. The subcommissural organ and the development of the posterior commissure. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2012; 296:63-137. [PMID: 22559938 DOI: 10.1016/b978-0-12-394307-1.00002-3] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Growing axons navigate through the developing brain by means of axon guidance molecules. Intermediate targets producing such signal molecules are used as guideposts to find distal targets. Glial, and sometimes neuronal, midline structures represent intermediate targets when axons cross the midline to reach the contralateral hemisphere. The subcommissural organ (SCO), a specialized neuroepithelium located at the dorsal midline underneath the posterior commissure, releases SCO-spondin, a large glycoprotein belonging to the thrombospondin superfamily that shares molecular domains with axonal pathfinding molecules. Several evidences suggest that the SCO could be involved in the development of the PC. First, both structures display a close spatiotemporal relationship. Second, certain mutants lacking an SCO present an abnormal PC. Third, some axonal guidance molecules are expressed by SCO cells. Finally, SCO cells, the Reissner's fiber (the aggregated form of SCO-spondin), or synthetic peptides from SCO-spondin affect the neurite outgrowth or neuronal aggregation in vitro.
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Affiliation(s)
- Jesús M Grondona
- Departamento de Biología Celular, Genética y Fisiología, Facultad de Ciencias, Universidad de Málaga, Spain.
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Tan X, Shi SH. Neocortical neurogenesis and neuronal migration. WILEY INTERDISCIPLINARY REVIEWS-DEVELOPMENTAL BIOLOGY 2012; 2:443-59. [PMID: 24014417 DOI: 10.1002/wdev.88] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
The neocortex, the evolutionarily newest part of the cerebral cortex, controls nearly all aspects of behavior, including perception, language, and decision making. It contains an immense number of neurons that can be broadly divided into two groups, excitatory neurons and inhibitory interneurons. These neurons are predominantly produced through extensive progenitor cell divisions during the embryonic stages. Moreover, they are not randomly dispersed, but spatially organized into horizontal layers that are essential for neocortex function. The formation of this laminar structure requires exquisite control of neuronal migration from their birthplace to their final destination. Extensive research over the past decade has greatly advanced our understanding of the production and migration of both excitatory neurons and inhibitory interneurons in the developing neocortex. In this review, we aim to give an overview on the molecular and cellular processes of neocortical neurogenesis and neuronal migration.
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Affiliation(s)
- Xin Tan
- Developmental Biology Program, Memorial Sloan-Kettering Cancer Center, New York, NY, USA; BCMB Graduate Program, Weill Cornell Medical College, New York, NY, USA
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Slavotinek AM, Chao R, Vacik T, Yahyavi M, Abouzeid H, Bardakjian T, Schneider A, Shaw G, Sherr EH, Lemke G, Youssef M, Schorderet DF. VAX1 mutation associated with microphthalmia, corpus callosum agenesis, and orofacial clefting: the first description of a VAX1 phenotype in humans. Hum Mutat 2011; 33:364-8. [PMID: 22095910 DOI: 10.1002/humu.21658] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2011] [Accepted: 11/09/2011] [Indexed: 01/30/2023]
Abstract
Vax1 and Vax2 have been implicated in eye development and the closure of the choroid fissure in mice and zebrafish. We sequenced the coding exons of VAX1 and VAX2 in 70 patients with anophthalmia/microphthalmia (A/M). In VAX1, we observed homozygosity for two successive nucleotide substitutions c.453G>A and c.454C>A, predicting p.Arg152Ser, in a proband of Egyptian origin with microphthalmia, small optic nerves, cleft lip/palate, and corpus callosum agenesis. This mutation affects an invariant residue in the homeodomain of VAX1 and was absent from 96 Egyptian controls. It is likely that the mutation results in a loss of function, as the mutation results in a phenotype similar to the Vax1 homozygous null mouse. We did not identify any mutations in VAX2. This is the first description of a phenotype associated with a VAX1 mutation in humans and establishes VAX1 as a new causative gene for A/M.
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Affiliation(s)
- Anne M Slavotinek
- Department of Pediatrics, Division of Genetics, University of California, San Francisco, California 94143-0748, USA.
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Abstract
Pax6 encodes a highly conserved transcriptional regulator with two DNA-binding motifs, a paired domain and a paired-like homeodomain. Humans carrying PAX6 loss-of-function mutations suffer from abnormal development of the eyes (congenital aniridia) and brain. Small eye mice carrying Pax6 loss-of-function mutations provide a good model for these human conditions. Their analysis has demonstrated the critical importance of this transcription factor in multiple cell types and at several key stages of forebrain development. In the forebrain, Pax6 is critical for the establishment of the pallial-subpallial boundary, which separates dorsal (future cerebral cortex) and ventral (future striatum) telencephalic regions. Levels of Pax6 expression are critically important for cortical progenitor proliferation and its presence in a rostro-lateral(high) to caudo-medial(low) gradient in the cortex is necessary to establish rostro-lateral identities. Furthermore, axon guidance is disrupted in Pax6⁻/⁻ mutants: the majority of thalamocortical axons fail to enter the ventral telencephalon and those that do are unable to innervate their cortical targets. The extent to which the effects of Pax6 later in development are secondary to its effects in early patterning and proliferation remains largely unknown. This is likely to be clarified by future studies on the molecular mechanisms of action of Pax6 and, in particular, the identification of its downstream target genes. Such studies should also help generate an increasingly coherent understanding of how this pleiotropic transcription factor becomes involved in so many facets of neural development.
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Affiliation(s)
- Petrina A Georgala
- Genes and Development Group, Centre for Integrative Physiology, University of Edinburgh, Edinburgh EH89XD, United Kingdom.
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Asami M, Pilz GA, Ninkovic J, Godinho L, Schroeder T, Huttner WB, Götz M. The role of Pax6 in regulating the orientation and mode of cell division of progenitors in the mouse cerebral cortex. Development 2011; 138:5067-78. [PMID: 22031545 DOI: 10.1242/dev.074591] [Citation(s) in RCA: 87] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Successful brain development requires tight regulation of sequential symmetric and asymmetric cell division. Although Pax6 is known to exert multiple roles in the developing nervous system, its role in the regulation of cell division is unknown. Here, we demonstrate profound alterations in the orientation and mode of cell division in the cerebral cortex of mice deficient in Pax6 function (Pax6(Sey/Sey)) or after acute induced deletion of Pax6. Live imaging revealed an increase in non-vertical cellular cleavage planes, resulting in an increased number of progenitors with unequal inheritance of the apical membrane domain and adherens junctions in the absence of Pax6 function. This phenotype appears to be mediated by the direct Pax6 target Spag5, a microtubule-associated protein, reduced levels of which result in the replication of the Pax6 phenotype of altered cell division orientation. In addition, lack of Pax6 also results in premature delamination of progenitor cells from the apical surface due to an overall decrease in proteins mediating anchoring at the ventricular surface. Moreover, continuous long-term imaging in vitro revealed that Pax6-deficient progenitors generate daughter cells with asymmetric fates at higher frequencies. These data demonstrate a cell-autonomous role for Pax6 in regulating the mode of cell division independently of apicobasal polarity and cell-cell interactions. Taken together, our work reveals several direct effects that the transcription factor Pax6 has on the machinery that mediates the orientation and mode of cell division.
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Affiliation(s)
- Maki Asami
- Institute for Stem Cell Research, Helmholtz Zentrum München German Research Center for Environmental Health, Ingolstädter Landstr. 1, 85764 Neuherberg/Munich, Germany
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Aging-associated modulation in the expression of Pax6 in mouse brain. Cell Mol Neurobiol 2011; 32:209-18. [PMID: 21901510 DOI: 10.1007/s10571-011-9749-3] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2011] [Accepted: 08/13/2011] [Indexed: 12/21/2022]
Abstract
Symptoms like mental retardation, depression, and anxiety have been observed during aging. Almost similar phenotypes have been evident in patients having haploinsufficiency or mutations in Pax6, a transcriptional regulator. Since Pax6 regulates axon guidance, differentiation of neurons from glia, and neuronal migration, it has been considered as a marker of newly generated neurons. The immunohistochemical analysis of Pax6 positive cells and expression pattern of Pax6 in olfactory lobe, hippocampus, and cerebellum of aging mouse brain have been investigated. The number of Pax6 positive cells and level of Pax6 were reduced progressively in olfactory lobe, cerebellum, and hippocampus from postnatal day-zero (P0) to old age mice. Pax6 positive cells were significantly lower in dentate gyrus, CA1, CA2, and CA3 regions of hippocampus, in mitral cell (MiCe), and internal plexiform (InPl) layers of olfactory lobe, and in granular cell (GrLa), and Purkinje's cell (PuCe) layers of cerebellum from P0 to old age. Thus, modulation in the expression of Pax6 and reduction in Pax6 positive cells show direct association of Pax6 with aging-related neuronal dystrophy.
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Swanson DJ, Goldowitz D. Experimental Sey mouse chimeras reveal the developmental deficiencies of Pax6-null granule cells in the postnatal cerebellum. Dev Biol 2011; 351:1-12. [DOI: 10.1016/j.ydbio.2010.11.018] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2010] [Revised: 11/06/2010] [Accepted: 11/10/2010] [Indexed: 10/18/2022]
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Umeda T, Takashima N, Nakagawa R, Maekawa M, Ikegami S, Yoshikawa T, Kobayashi K, Okanoya K, Inokuchi K, Osumi N. Evaluation of Pax6 mutant rat as a model for autism. PLoS One 2010; 5:e15500. [PMID: 21203536 PMCID: PMC3006426 DOI: 10.1371/journal.pone.0015500] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2010] [Accepted: 10/04/2010] [Indexed: 01/31/2023] Open
Abstract
Autism is a highly variable brain developmental disorder and has a strong genetic basis. Pax6 is a pivotal player in brain development and maintenance. It is expressed in embryonic and adult neural stem cells, in astrocytes in the entire central nervous system, and in neurons in the olfactory bulb, amygdala, thalamus, and cerebellum, functioning in highly context-dependent manners. We have recently reported that Pax6 heterozygous mutant (rSey2/+) rats with a spontaneous mutation in the Pax6 gene, show impaired prepulse inhibition (PPI). In the present study, we further examined behaviors of rSey2/+ rats and revealed that they exhibited abnormality in social interaction (more aggression and withdrawal) in addition to impairment in rearing activity and in fear-conditioned memory. Ultrasonic vocalization (USV) in rSey2+ rat pups was normal in male but abnormal in female. Moreover, treatment with clozapine successfully recovered the defects in sensorimotor gating function, but not in fear-conditioned memory. Taken together with our prior human genetic data and results in other literatures, rSey2/+ rats likely have some phenotypic components of autism.
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Affiliation(s)
- Toshiko Umeda
- Division of Developmental Neuroscience, Tohoku University Graduate School of Medicine, Sendai, Japan
| | - Noriko Takashima
- Laboratory for Behavioral and Developmental Disorders, RIKEN Brain Science Institute, Wako, Japan
- Mitsubishi Kagaku Institute of Life Sciences (MITILS), Tokyo, Japan
| | - Ryoko Nakagawa
- Laboratory for Biolinguistics, RIKEN Brain Science Institute, Wako, Japan
| | - Motoko Maekawa
- Laboratory for Molecular Psychiatry, RIKEN Brain Science Institute, Wako, Japan
| | - Shiro Ikegami
- Mitsubishi Kagaku Institute of Life Sciences (MITILS), Tokyo, Japan
- Department of Psychology, Saitama Institute of Technology, Fukaya, Japan
| | - Takeo Yoshikawa
- Laboratory for Molecular Psychiatry, RIKEN Brain Science Institute, Wako, Japan
| | - Kazuto Kobayashi
- Department of Molecular Genetics, Institute of Biomedical Sciences, Fukushima Medical University School of Medicine, Fukushima, Japan
| | - Kazuo Okanoya
- Laboratory for Biolinguistics, RIKEN Brain Science Institute, Wako, Japan
| | - Kaoru Inokuchi
- Mitsubishi Kagaku Institute of Life Sciences (MITILS), Tokyo, Japan
- Department of Biochemistry, Faculty of Medicine, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, Toyama, Japan
| | - Noriko Osumi
- Division of Developmental Neuroscience, Tohoku University Graduate School of Medicine, Sendai, Japan
- * E-mail:
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Zhang X, Huang CT, Chen J, Pankratz MT, Xi J, Li J, Yang Y, Lavaute TM, Li XJ, Ayala M, Bondarenko GI, Du ZW, Jin Y, Golos TG, Zhang SC. Pax6 is a human neuroectoderm cell fate determinant. Cell Stem Cell 2010; 7:90-100. [PMID: 20621053 DOI: 10.1016/j.stem.2010.04.017] [Citation(s) in RCA: 333] [Impact Index Per Article: 23.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2009] [Revised: 12/11/2009] [Accepted: 04/19/2010] [Indexed: 01/28/2023]
Abstract
The transcriptional regulation of neuroectoderm (NE) specification is unknown. Here we show that Pax6 is uniformly expressed in early NE cells of human fetuses and those differentiated from human embryonic stem cells (hESCs). This is in contrast to the later expression of Pax6 in restricted mouse brain regions. Knockdown of Pax6 blocks NE specification from hESCs. Overexpression of either Pax6a or Pax6b, but not Pax6triangle upPD, triggers hESC differentiation. However, only Pax6a converts hESCs to NE. In contrast, neither loss nor gain of function of Pax6 affects mouse NE specification. Both Pax6a and Pax6b bind to pluripotent gene promoters but only Pax6a binds to NE genes during human NE specification. These findings indicate that Pax6 is a transcriptional determinant of the human NE and suggest that Pax6a and Pax6b coordinate with each other in determining the transition from pluripotency to the NE fate in human by differentially targeting pluripotent and NE genes.
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Affiliation(s)
- Xiaoqing Zhang
- Waisman Center and the WiCell Institute, Madison, WI 53705, USA
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Georgala PA, Manuel M, Price DJ. The generation of superficial cortical layers is regulated by levels of the transcription factor Pax6. ACTA ACUST UNITED AC 2010; 21:81-94. [PMID: 20413449 DOI: 10.1093/cercor/bhq061] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The ventricular zone (VZ) of the embryonic dorsal telencephalon is a major site for generating cortical projection neurons. The transcription factor Pax6 is highly expressed in apical progenitors (APs) residing in the VZ from the earliest stages of corticogenesis. Previous studies mainly focused on Pax6(-/-) mice have implicated Pax6 in regulating cortical progenitor proliferation, neurogenesis, and formation of superficial cortical layers. We analyzed the developing cortex of PAX77 transgenic mice that overexpress Pax6 in its normal domains of expression. We show that Pax6 overexpression increases cell cycle length of APs and drives the system toward neurogenesis. These effects are specific to late stages of corticogenesis, when superficial layer neurons are normally generated, in cortical regions that express Pax6 at the highest levels. The number of superficial layer neurons is reduced in postnatal PAX77 mice, whereas radial migration and lamina specification of cortical neurons are not affected by Pax6 overexpression. Conditional deletion of Pax6 in cortical progenitors at midstages of corticogenesis, by using a tamoxifen-inducible Emx1-CreER line, affected both numbers and specification of late-born neurons in superficial layers of the mutant cortex. Our analyses suggest that correct levels of Pax6 are essential for normal production of superficial layers of the cortex.
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Affiliation(s)
- Petrina A Georgala
- Centre for Integrative Physiology, School of Biomedical Sciences, Genes and Development Group, The University of Edinburgh, Edinburgh, UK.
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Emx1-lineage progenitors differentially contribute to neural diversity in the striatum and amygdala. J Neurosci 2010; 29:15933-46. [PMID: 20016109 DOI: 10.1523/jneurosci.2525-09.2009] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
In the developing mammalian basal telencephalon, neural progenitors from the subpallium generate the majority of inhibitory medium spiny neurons (MSNs) in the striatum, while both pallial- and subpallial-derived progenitors contribute to excitatory and inhibitory neuronal diversity in the amygdala. Using a combination of approaches, including genetic fate mapping, cell birth dating, cell migration assays, and electrophysiology, we find that cells derived from the Emx1 lineage contribute to two distinct neuronal populations in the mature basal forebrain: inhibitory MSNs in the striatum and functionally distinct subclasses of excitatory neurons in the amygdala. Our cell birth-dating studies reveal that these two populations are born at different times during early neurogenesis, with the amygdala population born before the MSNs. In the striatum, Emx1-lineage neurons represent a unique subpopulation of MSNs: they are disproportionately localized to the dorsal striatum, are found in dopamine receiving, reelin-positive patches, and are born throughout striatal neurogenesis. In addition, our data suggest that a subpopulation of these Emx1-lineage cells originate in the pallium and subsequently migrate to the developing striatum and amygdala. Our intersectional fate-mapping analysis further reveals that Emx1-lineage cells that coexpress Dlx exclusively generate MSNs but do not contribute to the excitatory neurons in the amygdala. Thus, both the timing of neurogenesis and differential combinatorial gene expression appear to be key determinants of striatal versus amygdala fate decisions of Emx1-lineage cells.
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Chanas SA, Collinson JM, Ramaesh T, Dorà N, Kleinjan DA, Hill RE, West JD. Effects of elevated Pax6 expression and genetic background on mouse eye development. Invest Ophthalmol Vis Sci 2009; 50:4045-59. [PMID: 19387074 PMCID: PMC2763115 DOI: 10.1167/iovs.07-1630] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE To analyze the effects of Pax6 overexpression and its interaction with genetic background on eye development. METHODS Histologic features of eyes from hemizygous PAX77(+/-) transgenic (high Pax6 gene dose) and wild-type mice were compared on different genetic backgrounds. Experimental PAX77(+/-)<-->wild-type and control wild-type<-->wild-type chimeras were analyzed to investigate the causes of abnormal eye development in PAX77(+/-) mice. RESULTS PAX77(+/-) mice showed an overlapping but distinct spectrum of eye abnormalities to Pax6(+/-) heterozygotes (low Pax6 dose). Some previously reported PAX77(+/-) eye abnormalities did not occur on all three genetic backgrounds examined. Several types of eye abnormalities occurred in the experimental PAX77(+/-)<-->wild-type chimeras, and they occurred more frequently in chimeras with higher contributions of PAX77(+/-) cells. Groups of RPE cells intruded into the optic nerve sheath, indicating that the boundary between the retina and optic nerve may be displaced. Both PAX77(+/-) and wild-type cells were involved in this ingression and in retinal folds, suggesting that neither effect was cell-autonomous. Cell-autonomous effects included failure of PAX77(+/-) and wild-type cells to mix normally and overrepresentation of PAX77(+/-) in the lens epithelium and RPE. CONCLUSIONS The extent of PAX77(+/-) eye abnormalities depended on PAX77(+/-) genotype, genetic background, and stochastic variation. Chimera analysis identified two types of cell-autonomous effects of the PAX77(+/-) genotype. Abnormal cell mixing between PAX77(+/-) and wild-type cells suggests altered expression of cell surface adhesion molecules. Some phenotypic differences between PAX77(+/-)<-->wild-type and Pax6(+/-)<-->wild-type chimeras may reflect differences in the levels of PAX77(+/-) and Pax6(+/-) contributions to chimeric lenses.
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Affiliation(s)
- Simon A. Chanas
- Division of Reproductive and Developmental Sciences, Genes and Development Group, University of Edinburgh, Edinburgh, Scotland, United Kingdom
| | - J. Martin Collinson
- School of Medical Sciences, College of Life Sciences and Medicine, University of Aberdeen, Institute of Medical Sciences, Aberdeen, Scotland, United Kingdom
| | - Thaya Ramaesh
- Division of Reproductive and Developmental Sciences, Genes and Development Group, University of Edinburgh, Edinburgh, Scotland, United Kingdom
- Department of Clinical and Surgical Sciences, Ophthalmology Section, University of Edinburgh, Princess Alexandra Eye Pavilion, Royal Infirmary of Edinburgh, Edinburgh, Scotland, United Kingdom
| | - Natalie Dorà
- School of Medical Sciences, College of Life Sciences and Medicine, University of Aberdeen, Institute of Medical Sciences, Aberdeen, Scotland, United Kingdom
| | - Dirk A. Kleinjan
- Medical and Developmental Genetics Section, MRC Human Genetics Unit, Edinburgh, Scotland, United Kingdom
| | - Robert E. Hill
- Medical and Developmental Genetics Section, MRC Human Genetics Unit, Edinburgh, Scotland, United Kingdom
| | - John D. West
- Division of Reproductive and Developmental Sciences, Genes and Development Group, University of Edinburgh, Edinburgh, Scotland, United Kingdom
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Hsieh YW, Yang XJ. Dynamic Pax6 expression during the neurogenic cell cycle influences proliferation and cell fate choices of retinal progenitors. Neural Dev 2009; 4:32. [PMID: 19686589 PMCID: PMC2741438 DOI: 10.1186/1749-8104-4-32] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2009] [Accepted: 08/17/2009] [Indexed: 01/27/2023] Open
Abstract
Background The paired homeobox protein Pax6 is essential for proliferation and pluripotency of retinal progenitors. However, temporal changes in Pax6 protein expression associated with the generation of various retinal neurons have not been characterized with regard to the cell cycle. Here, we examine the dynamic changes of Pax6 expression among chicken retinal progenitors as they progress through the neurogenic cell cycle, and determine the effects of altered Pax6 levels on retinogenesis. Results We provide evidence that during the preneurogenic to neurogenic transition, Pax6 protein levels in proliferating progenitor cells are down-regulated. Neurogenic retinal progenitors retain a relatively low level of Pax6 protein, whereas postmitotic neurons either elevate or extinguish Pax6 expression in a cell type-specific manner. Cell imaging and cell cycle analyses show that neurogenic progenitors in the S phase of the cell cycle contain low levels of Pax6 protein, whereas a subset of progenitors exhibits divergent levels of Pax6 protein upon entering the G2 phase of the cell cycle. We also show that M phase cells contain varied levels of Pax6, and some correlate with the onset of early neuronal marker expression, forecasting cell cycle exit and cell fate commitment. Furthermore, either elevating or knocking down Pax6 attenuates cell proliferation and results in increased cell death. Reducing Pax6 decreases retinal ganglion cell genesis and enhances cone photoreceptor and amacrine interneuron production, whereas elevating Pax6 suppresses cone photoreceptor and amacrine cell fates. Conclusion These studies demonstrate for the first time quantitative changes in Pax6 protein expression during the preneurogenic to neurogenic transition and during the neurogenic cell cycle. The results indicate that Pax6 protein levels are stringently controlled in proliferating progenitors. Maintaining a relatively low Pax6 protein level is necessary for S phase re-entry, whereas rapid accumulation or reduction of Pax6 protein during the G2/M phase of the cell cycle may be required for specific neuronal fates. These findings thus provide novel insights on the dynamic regulation of Pax6 protein among neurogenic progenitors and the temporal frame of neuronal fate determination.
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Affiliation(s)
- Yi-Wen Hsieh
- Jules Stein Eye Institute and Department of Ophthalmology, Molecular Biology Institute, University of California, David Geffen School of Medicine, Stein Plaza, Los Angeles, CA 90095, USA.
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40
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Selective cortical layering abnormalities and behavioral deficits in cortex-specific Pax6 knock-out mice. J Neurosci 2009; 29:8335-49. [PMID: 19571125 DOI: 10.1523/jneurosci.5669-08.2009] [Citation(s) in RCA: 91] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The transcription factor Pax6 has been implicated in neocortical neurogenesis in vertebrates, including humans. Analyses of the role of Pax6 in layer formation and cognitive abilities have been hampered by perinatal lethality of Pax6 mutants. Here, we generated viable mutants exhibiting timed, restricted inactivation of Pax6 during early and late cortical neurogenesis using Emx1-Cre and hGFAP-Cre lines, respectively. The disruption of Pax6 at the onset of neurogenesis using Emx1-Cre line resulted in premature cell cycle exit of early progenitors, increase of early born neuronal subsets located in the marginal zone and lower layers, and a nearly complete absence of upper layer neurons, especially in the rostral cortex. Furthermore, progenitors, which accumulated in the enlarged germinal neuroepithelium at the pallial/subpallial border in the Pax6 mutants, produced an excess of oligodendrocytes. The inactivation of Pax6 after generation of the lower neuronal layers using hGFAP-Cre line did not affect specification or numbers of late-born neurons, indicating that the severe reduction of upper layer neurons in Pax6 deficiency is mostly attributable to a depletion of the progenitor pool, available for late neurogenesis. We further show that Pax6(fl/fl);Emx1-Cre mutants exhibited deficiencies in sensorimotor information integration, and both hippocampus-dependent short-term and neocortex-dependent long-term memory recall. Because a majority of the morphological and behavior disabilities of the Pax6 mutant mice parallel abnormalities reported for aniridia patients, a condition caused by PAX6 haploinsufficiency, the Pax6 conditional mutant mice generated here represent a valuable genetic tool to understand how the developmental cortical disruption can lead to a human behavior abnormality.
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Analysis of Pax6 contiguous gene deletions in the mouse, Mus musculus, identifies regions distinct from Pax6 responsible for extreme small-eye and belly-spotting phenotypes. Genetics 2009; 182:1077-88. [PMID: 19474196 DOI: 10.1534/genetics.109.104562] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
In the mouse Pax6 function is critical in a dose-dependent manner for proper eye development. Pax6 contiguous gene deletions were shown to be homozygous lethal at an early embryonic stage. Heterozygotes express belly spotting and extreme microphthalmia. The eye phenotype is more severe than in heterozygous Pax6 intragenic null mutants, raising the possibility that deletions are functionally different from intragenic null mutations or that a region distinct from Pax6 included in the deletions affects eye phenotype. We recovered and identified the exact regions deleted in three new Pax6 deletions. All are homozygous lethal at an early embryonic stage. None express belly spotting. One expresses extreme microphthalmia and two express the milder eye phenotype similar to Pax6 intragenic null mutants. Analysis of Pax6 expression levels and the major isoforms excluded the hypothesis that the deletions expressing extreme microphthalmia are directly due to the action of Pax6 and functionally different from intragenic null mutations. A region distinct from Pax6 containing eight genes was identified for belly spotting. A second region containing one gene (Rcn1) was identified for the extreme microphthalmia phenotype. Rcn1 is a Ca(+2)-binding protein, resident in the endoplasmic reticulum, participates in the secretory pathway and expressed in the eye. Our results suggest that deletion of Rcn1 directly or indirectly contributes to the eye phenotype in Pax6 contiguous gene deletions.
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Boretius S, Michaelis T, Tammer R, Ashery-Padan R, Frahm J, Stoykova A. In vivo MRI of altered brain anatomy and fiber connectivity in adult pax6 deficient mice. ACTA ACUST UNITED AC 2009; 19:2838-47. [PMID: 19329571 DOI: 10.1093/cercor/bhp057] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
The impact of developmental ablation of Pax6 function on morphology and functional connectivity of the adult cerebrum was studied in cortex-specific Pax6 knockout mice (Pax6cKO) using structural magnetic resonance imaging (MRI), manganese-enhanced MRI, and diffusion tensor MRI in conjunction with fiber tractography. Mutants presented with decreased volumes of total brain and olfactory bulb, reduced cortical thickness, and altered layering of the piriform cortex. Tracking of major neuronal fiber bundles revealed a disorganization of callosal fibers with an almost complete lack of interhemispheric connectivity. In Pax6cKO mice intrahemispheric callosal fibers as well as intracortical fibers were predominantly directed along a rostrocaudal orientation instead of a left-right and dorsoventral orientation found in controls. Fiber disorganization also involved the septohippocampal connection targeting mostly the lateral septal nucleus. The hippocampus was rostrally extended and its volume was increased relative to that of the forebrain and midbrain. Manganese-induced MRI signal enhancement in the CA3 region suggested a normal function of hippocampal pyramidal cells. Noteworthy, several morphologic disturbances in gray and white matter of Pax6cKO mice were similar to observations in human aniridia patients. The present findings indicate an important role of Pax6 in the development of both the cortex and cerebral fiber connectivity.
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Affiliation(s)
- Susann Boretius
- Biomedizinische NMR Forschungs GmbH am Max-Planck-Institut für biophysikalische Chemie, 37070 Göttingen, Germany.
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Wolf LV, Yang Y, Wang J, Xie Q, Braunger B, Tamm ER, Zavadil J, Cvekl A. Identification of pax6-dependent gene regulatory networks in the mouse lens. PLoS One 2009; 4:e4159. [PMID: 19132093 PMCID: PMC2612750 DOI: 10.1371/journal.pone.0004159] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2008] [Accepted: 11/21/2008] [Indexed: 11/20/2022] Open
Abstract
Lineage-specific DNA-binding transcription factors regulate development by activating and repressing particular set of genes required for the acquisition of a specific cell type. Pax6 is a paired domain and homeodomain-containing transcription factor essential for development of central nervous, olfactory and visual systems, as well as endocrine pancreas. Haploinsufficiency of Pax6 results in perturbed lens development and homeostasis. Loss-of-function of Pax6 is incompatible with lens lineage formation and results in abnormal telencephalic development. Using DNA microarrays, we have identified 559 genes expressed differentially between 1-day old mouse Pax6 heterozygous and wild type lenses. Of these, 178 (31.8%) were similarly increased and decreased in Pax6 homozygous embryonic telencephalon [Holm PC, Mader MT, Haubst N, Wizenmann A, Sigvardsson M, Götz M (2007) Loss- and gain-of-function analyses reveals targets of Pax6 in the developing mouse telencephalon. Mol Cell Neurosci 34: 99–119]. In contrast, 381 (68.2%) genes were differently regulated between the lens and embryonic telencephalon. Differential expression of nine genes implicated in lens development and homeostasis: Cspg2, Igfbp5, Mab21l2, Nrf2f, Olfm3, Spag5, Spock1, Spon1 and Tgfb2, was confirmed by quantitative RT-PCR, with five of these genes: Cspg2, Mab21l2, Olfm3, Spag5 and Tgfb2, identified as candidate direct Pax6 target genes by quantitative chromatin immunoprecipitation (qChIP). In Mab21l2 and Tgfb2 promoter regions, twelve putative individual Pax6-binding sites were tested by electrophoretic mobility shift assays (EMSAs) with recombinant Pax6 proteins. This led to the identification of two and three sites in the respective Mab21l2 and Tgfb2 promoter regions identified by qChIPs. Collectively, the present studies represent an integrative genome-wide approach to identify downstream networks controlled by Pax6 that control mouse lens and forebrain development.
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Affiliation(s)
- Louise V. Wolf
- The Departments of Ophthalmology and Visual Sciences and Genetics, Albert Einstein College of Medicine, Bronx, New York, United States of America
| | - Ying Yang
- The Departments of Ophthalmology and Visual Sciences and Genetics, Albert Einstein College of Medicine, Bronx, New York, United States of America
| | - Jinhua Wang
- NYU Cancer Institute, New York University Langone Medical Center, New York, New York, United States of America
| | - Qing Xie
- The Departments of Ophthalmology and Visual Sciences and Genetics, Albert Einstein College of Medicine, Bronx, New York, United States of America
| | - Barbara Braunger
- Institute of Human Anatomy and Embryology, University of Regensburg, Regensburg, Germany
| | - Ernst R. Tamm
- Institute of Human Anatomy and Embryology, University of Regensburg, Regensburg, Germany
| | - Jiri Zavadil
- NYU Cancer Institute, New York University Langone Medical Center, New York, New York, United States of America
- Department of Pathology, New York University Langone Medical Center, New York, New York, United States of America
| | - Ales Cvekl
- The Departments of Ophthalmology and Visual Sciences and Genetics, Albert Einstein College of Medicine, Bronx, New York, United States of America
- * E-mail:
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Albertson RC, Cresko W, Detrich HW, Postlethwait JH. Evolutionary mutant models for human disease. Trends Genet 2008; 25:74-81. [PMID: 19108930 DOI: 10.1016/j.tig.2008.11.006] [Citation(s) in RCA: 95] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2008] [Revised: 11/25/2008] [Accepted: 11/26/2008] [Indexed: 10/21/2022]
Abstract
Although induced mutations in traditional laboratory animals have been valuable as models for human diseases, they have some important limitations. Here, we propose a complementary approach to discover genes and mechanisms that might contribute to human disorders: the analysis of evolutionary mutant models in which adaptive phenotypes mimic maladaptive human diseases. If the type and mode of action of mutations favored by natural selection in wild populations are similar to those that contribute to human diseases, then studies in evolutionary mutant models have the potential to identify novel genetic factors and gene-by-environment interactions that affect human health and underlie human disease.
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Affiliation(s)
- R Craig Albertson
- Department of Biology, Syracuse University, 130 College Place, Syracuse, NY 13244, USA.
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Aronne MP, Evrard SG, Mirochnic S, Brusco A. Prenatal Ethanol Exposure Reduces the Expression of the Transcriptional FactorPax6in the Developing Rat Brain. Ann N Y Acad Sci 2008; 1139:478-98. [DOI: 10.1196/annals.1432.006] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Tuoc TC, Stoykova A. Trim11 modulates the function of neurogenic transcription factor Pax6 through ubiquitin-proteosome system. Genes Dev 2008; 22:1972-86. [PMID: 18628401 DOI: 10.1101/gad.471708] [Citation(s) in RCA: 91] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
The transcription factor Pax6 is an important developmental regulator. Spatiotemporal control of Pax6 expression during embryogenesis is crucial for regulating distinct aspects of cortical development. Here, we report that Trim11, a member of the TRIM/RBCC protein family of E3 ubiquitin ligases, interacts with Pax6 and mediates Pax6 degradation via the ubiquitin-proteasome system. Trim11 overexpression decreases endogenous Pax6 protein levels and represses Pax6 functions, including Pax6-dependent transactivation and neurogenesis. Abrogation of endogenous Trim11 expression in the developing cortex increases the level of insoluble forms of Pax6 and enhances apoptosis. We provide evidence that the B30.2 domain of Trim11 is essential for the clearance of insoluble cell proteins. Furthermore, we show that the expression of Trim11 is directly regulated by Pax6 in developing cortex in vivo. Our findings indicate that an autoregulatory feedback loop between Trim11 and Pax6 maintains a balance between the levels of Pax6 and Trim11 proteins in cortical progenitors, having an essential role for the Pax6-dependent neurogenesis.
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Affiliation(s)
- Tran Cong Tuoc
- Max-Planck-Institute for Biophysical Chemistry, Göttingen 37077, Germany
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47
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Carney RSE, Cocas LA, Hirata T, Mansfield K, Corbin JG. Differential regulation of telencephalic pallial-subpallial boundary patterning by Pax6 and Gsh2. ACTA ACUST UNITED AC 2008; 19:745-59. [PMID: 18701439 DOI: 10.1093/cercor/bhn123] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
In the embryonic telencephalon, the pallial-subpallial boundary (PSB) separates the dorsal Pax6+ pallium from the ventral Gsh2+ subpallium. Previous studies have revealed that this region is a source of cells that will populate both the olfactory bulb and basal telencephalic limbic system. However, the level of progenitor cell heterogeneity and developmental genetic regulation of this progenitor region remains to be fully elucidated. In this study we carried out a comprehensive analysis of gene expression patterns at the PSB, in addition to an examination of the combinatorial function of Pax6 and Gsh2 in the specification of the PSB. First, we reveal that the PSB is comprised of a complex mix of molecularly distinct progenitor pools. In addition, by analysis of single Sey, Gsh2, and Sey/Gsh2 double mutant mice, we demonstrate that both Pax6 and Gsh2 are directly required for major aspects of PSB progenitor specification. Our analysis also reveals that the establishment of the epidermal growth factor receptor positive lateral cortical stream migratory route to the basal telencephalon is Pax6 dependent. Thus, in addition to their well-characterized cross-repressive roles in dorsal/ventral patterning our analyses reveal important novel functions of Gsh2 and Pax6 in the regulation of PSB progenitor pool specification and patterning.
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Affiliation(s)
- Rosalind S E Carney
- Center for Neuroscience Research, Children's Research Institute, Children's National Medical Center, Washington, DC 20010, USA
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Sisodiya S. Brain structure, function, and genetics revealed by studies of the eye and face. Curr Opin Neurol 2008; 21:404-9. [DOI: 10.1097/wco.0b013e3283052d0c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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49
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Relationship of Pax6 activity levels to the extent of eye development in the mouse, Mus musculus. Genetics 2008; 179:1345-55. [PMID: 18562673 DOI: 10.1534/genetics.108.088591] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
In this study we extend the mouse Pax6 mutant allelic series to include a homozygous and hemizygous viable hypomorph allele. The Pax6(132-14Neu) allele is a Phe272Ile missense mutation within the third helix of the homeodomain. The mutant Pax6 homeodomain shows greatly reduced binding activity to the P3 DNA binding target. Glucagon-promoter activation by the entire mutant Pax6 product of a reporter gene driven by the G1 paired and homeodomain DNA binding target was slightly increased. We constructed mutant Pax6 genotypes such that Pax6 activity ranged between 100 and 0% and show that the extent of eye development is progressively reduced as Pax6 activity decreased. Two apparent thresholds identify three groups in which the extent of eye development abruptly shifted from complete eye at the highest levels of Pax6 to a rudimentary eye at intermediate levels of Pax6 to very early termination of eye development at the lowest levels of Pax6. Of the two Pax6-positive regions that participate in eye development, the surface ectoderm, which develops into the lens vesicle and the cornea, is more sensitive to reduced levels of Pax6 activity than the optic vesicle, which develops into the inner and outer retinal layers.
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Osumi N, Shinohara H, Numayama-Tsuruta K, Maekawa M. Concise review: Pax6 transcription factor contributes to both embryonic and adult neurogenesis as a multifunctional regulator. Stem Cells 2008; 26:1663-72. [PMID: 18467663 DOI: 10.1634/stemcells.2007-0884] [Citation(s) in RCA: 273] [Impact Index Per Article: 17.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Pax6 is a highly conserved transcription factor among vertebrates and is important in various developmental processes in the central nervous system (CNS), including patterning of the neural tube, migration of neurons, and formation of neural circuits. In this review, we focus on the role of Pax6 in embryonic and postnatal neurogenesis, namely, production of new neurons from neural stem/progenitor cells, because Pax6 is intensely expressed in these cells from the initial stage of CNS development and in neurogenic niches (the subgranular zone of the hippocampal dentate gyrus and the subventricular zone of the lateral ventricle) throughout life. Pax6 is a multifunctional player regulating proliferation and differentiation through the control of expression of different downstream molecules in a highly context-dependent manner.
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Affiliation(s)
- Noriko Osumi
- Division of Developmental Neuroscience, Center for Translational and Advanced Animal Research, Tohoku University School of Medicine, 2-1, Seiryo-machi, Aoba-ku, Sendai 980-8575, Japan.
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