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Pan Q, Luo J, Jiang Y, Wang Z, Lu K, Chen T. Medaka (Oryzias latipes) Olpax6.2 acquires maternal inheritance and germ cells expression, but was functionally degenerated in the eye. Gene 2023; 872:147439. [PMID: 37094695 DOI: 10.1016/j.gene.2023.147439] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2023] [Revised: 03/20/2023] [Accepted: 04/18/2023] [Indexed: 04/26/2023]
Abstract
Gene duplication provides raw material for the evolution of genetic and phenotypic complexity. It has remained a long-standing mystery how duplicated genes evolve into new genes by neofunctionalization via the acquisition of new expression and/or activity and simultaneous loss of the old expression and activity. Fishes have many gene duplicates from whole genome duplication, making them excellent for studying the evolution of gene duplicates. In the fish medaka (Oryzias latipes), an ancestral pax6 gene has given rise to Olpax6.1 and Olpax6.2. Here we report that medaka Olpax6.2 is evolving towards neofunctionalization. A chromosomal syntenic analysis indicated that Olpax6.1 and Olpax6.2 are structurally co-homologous to the single pax6 in other organisms. Interestingly, Olpax6.2 maintains all conserved coding exons but loses the non-coding exons of Olpax6.1, and has 4 promoters versus 8 in Olpax6.1. RT-PCR revealed that Olpax6.2 maintained expression in the brain eye, pancreas as Olpax6.1. Surprisingly, Olpax6.2 also exhibited maternal inheritance and gonadal expression by RT-PCR, in situ hybridization and RNA transcriptome analysis. The expression and distribution of Olpax6.2 is not different from Olpax6.1 in the adult brain, eye and pancreas, but exhibited overlapping and distinct expression in early embryogenesis. We show that ovarian Olpax6.2 expression occurs in female germ cells. Olpax6.2 knockout showed no obvious defect in eye development, while Olpax6.1 F0 mutant have severe defects in eye development. Thus, Olpax6.2 has acquired maternal inheritance and germ cell expression, but was functionally degenerated in the eye, making this gene as an excellent model to study the neofunctionalization of duplicated genes.
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Affiliation(s)
- Qihua Pan
- Key Laboratory of Healthy Mariculture for the East China Sea, Ministry of Agriculture, Fisheries College, Engineering Research Center of the Modern Technology for Eel Industry, Ministry of Education, Jimei University, Xiamen, China; College of Fisheries, Key Laboratory of Freshwater Animal Breeding, Ministry of Agriculture, Huazhong Agricultural University, Wuhan, Hubei, China
| | - Junzhi Luo
- College of Fisheries, Key Laboratory of Freshwater Animal Breeding, Ministry of Agriculture, Huazhong Agricultural University, Wuhan, Hubei, China
| | - Yuewen Jiang
- College of Fisheries, Key Laboratory of Freshwater Animal Breeding, Ministry of Agriculture, Huazhong Agricultural University, Wuhan, Hubei, China
| | - Zhi Wang
- College of Fisheries, Key Laboratory of Freshwater Animal Breeding, Ministry of Agriculture, Huazhong Agricultural University, Wuhan, Hubei, China
| | - Ke Lu
- College of Fisheries, Key Laboratory of Freshwater Animal Breeding, Ministry of Agriculture, Huazhong Agricultural University, Wuhan, Hubei, China
| | - Tiansheng Chen
- Key Laboratory of Healthy Mariculture for the East China Sea, Ministry of Agriculture, Fisheries College, Engineering Research Center of the Modern Technology for Eel Industry, Ministry of Education, Jimei University, Xiamen, China; College of Fisheries, Key Laboratory of Freshwater Animal Breeding, Ministry of Agriculture, Huazhong Agricultural University, Wuhan, Hubei, China.
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2
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Lacomme M, Medevielle F, Bourbon HM, Thierion E, Kleinjan DJ, Roussat M, Pituello F, Bel-Vialar S. A long range distal enhancer controls temporal fine-tuning of PAX6 expression in neuronal precursors. Dev Biol 2018; 436:94-107. [PMID: 29486153 DOI: 10.1016/j.ydbio.2018.02.015] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2017] [Revised: 02/22/2018] [Accepted: 02/22/2018] [Indexed: 12/14/2022]
Abstract
Proper embryonic development relies on a tight control of spatial and temporal gene expression profiles in a highly regulated manner. One good example is the ON/OFF switching of the transcription factor PAX6 that governs important steps of neurogenesis. In the neural tube PAX6 expression is initiated in neural progenitors through the positive action of retinoic acid signaling and downregulated in neuronal precursors by the bHLH transcription factor NEUROG2. How these two regulatory inputs are integrated at the molecular level to properly fine tune temporal PAX6 expression is not known. In this study we identified and characterized a 940-bp long distal cis-regulatory module (CRM), located far away from the PAX6 transcription unit and which conveys positive input from RA signaling pathway and indirect repressive signal(s) from NEUROG2. These opposing regulatory signals are integrated through HOMZ, a 94 bp core region within E940 which is evolutionarily conserved in distant organisms such as the zebrafish. We show that within HOMZ, NEUROG2 and RA exert their opposite temporal activities through a short 60 bp region containing a functional RA-responsive element (RARE). We propose a model in which retinoic acid receptors (RARs) and NEUROG2 repressive target(s) compete on the same DNA motif to fine tune temporal PAX6 expression during the course of spinal neurogenesis.
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Affiliation(s)
- Marine Lacomme
- Centre de Biologie du Développement (CBD), Centre de Biologie Intégrative (CBI), Université de Toulouse, CNRS, UPS, France; Cellular Neurobiology Research Unit, Institut de recherches cliniques de Montréal (IRCM), Montreal, Québec, Canada
| | - François Medevielle
- Centre de Biologie du Développement (CBD), Centre de Biologie Intégrative (CBI), Université de Toulouse, CNRS, UPS, France
| | - Henri-Marc Bourbon
- Centre de Biologie du Développement (CBD), Centre de Biologie Intégrative (CBI), Université de Toulouse, CNRS, UPS, France
| | - Elodie Thierion
- Cancer Research UK Cambridge Institute, University of Cambridge, Cambridge, United Kingdom
| | - Dirk-Jan Kleinjan
- 1UK Centre for Mammalian Synthetic Biology, University of Edinburgh, Edinburgh, United Kingdom
| | - Mélanie Roussat
- Centre de Biologie du Développement (CBD), Centre de Biologie Intégrative (CBI), Université de Toulouse, CNRS, UPS, France
| | - Fabienne Pituello
- Centre de Biologie du Développement (CBD), Centre de Biologie Intégrative (CBI), Université de Toulouse, CNRS, UPS, France
| | - Sophie Bel-Vialar
- Centre de Biologie du Développement (CBD), Centre de Biologie Intégrative (CBI), Université de Toulouse, CNRS, UPS, France
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3
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Verma N, Pan H, Doré LC, Shukla A, Li QV, Pelham-Webb B, Teijeiro V, González F, Krivtsov A, Chang CJ, Papapetrou EP, He C, Elemento O, Huangfu D. TET proteins safeguard bivalent promoters from de novo methylation in human embryonic stem cells. Nat Genet 2017; 50:83-95. [PMID: 29203910 PMCID: PMC5742051 DOI: 10.1038/s41588-017-0002-y] [Citation(s) in RCA: 137] [Impact Index Per Article: 19.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2016] [Accepted: 10/25/2017] [Indexed: 12/22/2022]
Abstract
The TET enzymes oxidize 5-methylcytosine to 5-hydroxymethylcytosine, which can lead to DNA demethylation. However, direct connections between TET-mediated DNA demethylation and transcriptional output are difficult to establish due to challenges of distinguishing global versus locus-specific effects. Here we show that TET1/2/3 triple knockout (TKO) human embryonic stem cells (hESCs) exhibit prominent bivalent promoter hypermethylation without an overall corresponding gene expression decrease in the undifferentiated state. Focusing on the bivalent PAX6 locus, we find increased DNMT3B binding is associated with promoter hypermethylation, which precipitates a neural differentiation defect and failure of PAX6 induction during differentiation. dCas9-mediated locus-specific demethylation and global inactivation of DNMT3B in TKO hESCs partially reverses the hypermethylation at the PAX6 promoter and improves differentiation to neuroectoderm. Taken together with further genome-wide methylation and TET1 and DNMT3B ChIP-Seq analysis, we conclude that the TET proteins safeguard bivalent promoters from de novo methylation to ensure robust lineage-specific transcription upon differentiation.
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Affiliation(s)
- Nipun Verma
- Developmental Biology Program, Sloan Kettering Institute, New York, NY, USA.,Weill Graduate School of Medical Sciences at Cornell University/The Rockefeller University/Sloan Kettering Institute Tri-Institutional MD-PhD Program, New York, NY, USA
| | - Heng Pan
- Department of Physiology and Biophysics, Englander Institute for Precision Medicine, Institute for Computational Biomedicine, Weill Cornell Medical College, New York, NY, USA.,Weill Cornell Graduate School of Medical Sciences, Weill Cornell Medical College, New York, NY, USA
| | - Louis C Doré
- Department of Chemistry, Department of Biochemistry and Molecular Biology, Institute for Biophysical Dynamics, Howard Hughes Medical Institute, University of Chicago, Chicago, IL, USA
| | - Abhijit Shukla
- Developmental Biology Program, Sloan Kettering Institute, New York, NY, USA
| | - Qing V Li
- Developmental Biology Program, Sloan Kettering Institute, New York, NY, USA.,Louis V. Gerstner Jr. Graduate School of Biomedical Sciences, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Bobbie Pelham-Webb
- Weill Graduate School of Medical Sciences at Cornell University/The Rockefeller University/Sloan Kettering Institute Tri-Institutional MD-PhD Program, New York, NY, USA
| | - Virginia Teijeiro
- Developmental Biology Program, Sloan Kettering Institute, New York, NY, USA.,Weill Cornell Graduate School of Medical Sciences, Weill Cornell Medical College, New York, NY, USA
| | - Federico González
- Developmental Biology Program, Sloan Kettering Institute, New York, NY, USA.,Institute for Bioengineering of Catalonia (IBEC), Barcelona, Spain
| | - Andrei Krivtsov
- Cancer Biology and Genetics Program, Sloan Kettering Institute, New York, NY, USA
| | - Chan-Jung Chang
- Department of Oncological Sciences and Black Family Stem Cell Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Eirini P Papapetrou
- Department of Oncological Sciences and Black Family Stem Cell Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Chuan He
- Department of Chemistry, Department of Biochemistry and Molecular Biology, Institute for Biophysical Dynamics, Howard Hughes Medical Institute, University of Chicago, Chicago, IL, USA
| | - Olivier Elemento
- Department of Physiology and Biophysics, Englander Institute for Precision Medicine, Institute for Computational Biomedicine, Weill Cornell Medical College, New York, NY, USA.
| | - Danwei Huangfu
- Developmental Biology Program, Sloan Kettering Institute, New York, NY, USA.
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4
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Chen T, Cavari B, Schartl M, Hong Y. Identification and Expression of Conserved and Novel RNA Variants of Medakapax6bGene. JOURNAL OF EXPERIMENTAL ZOOLOGY PART B-MOLECULAR AND DEVELOPMENTAL EVOLUTION 2017; 328:412-422. [PMID: 28547909 DOI: 10.1002/jez.b.22742] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/23/2016] [Revised: 03/18/2017] [Accepted: 03/24/2017] [Indexed: 11/10/2022]
Affiliation(s)
- Tiansheng Chen
- Key Laboratory of Freshwater Animal Breeding; Ministry of Agriculture and College of Fisheries; Huazhong Agricultural University; Wuhan Hubei China
| | - Benzion Cavari
- Israel Oceanographic and Limnological Research; Tel Shikmona; Halfa Israel
| | - Manfred Schartl
- Department of Physiological Chemistry I, Biocenter; University of Würzburg; Würzburg Germany
| | - Yunhan Hong
- Department of Biological Sciences; National University of Singapore; Singapore
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5
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Hickmott JW, Chen CY, Arenillas DJ, Korecki AJ, Lam SL, Molday LL, Bonaguro RJ, Zhou M, Chou AY, Mathelier A, Boye SL, Hauswirth WW, Molday RS, Wasserman WW, Simpson EM. PAX6 MiniPromoters drive restricted expression from rAAV in the adult mouse retina. Mol Ther Methods Clin Dev 2016; 3:16051. [PMID: 27556059 PMCID: PMC4980111 DOI: 10.1038/mtm.2016.51] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2016] [Revised: 05/25/2016] [Accepted: 06/13/2016] [Indexed: 12/15/2022]
Abstract
Current gene therapies predominantly use small, strong, and readily available ubiquitous promoters. However, as the field matures, the availability of small, cell-specific promoters would be greatly beneficial. Here we design seven small promoters from the human paired box 6 (PAX6) gene and test them in the adult mouse retina using recombinant adeno-associated virus. We chose the retina due to previous successes in gene therapy for blindness, and the PAX6 gene since it is: well studied; known to be driven by discrete regulatory regions; expressed in therapeutically interesting retinal cell types; and mutated in the vision-loss disorder aniridia, which is in need of improved therapy. At the PAX6 locus, 31 regulatory regions were bioinformatically predicted, and nine regulatory regions were constructed into seven MiniPromoters. Driving Emerald GFP, these MiniPromoters were packaged into recombinant adeno-associated virus, and injected intravitreally into postnatal day 14 mice. Four MiniPromoters drove consistent retinal expression in the adult mouse, driving expression in combinations of cell-types that endogenously express Pax6: ganglion, amacrine, horizontal, and Müller glia. Two PAX6-MiniPromoters drive expression in three of the four cell types that express PAX6 in the adult mouse retina. Combined, they capture all four cell types, making them potential tools for research, and PAX6-gene therapy for aniridia.
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Affiliation(s)
- Jack W Hickmott
- Centre for Molecular Medicine and Therapeutics at the BC Children’s Hospital, University of British Columbia, Vancouver, British Columbia, Canada
- Department of Medical Genetics, University of British Columbia, Vancouver, British Columbia, Canada
| | - Chih-yu Chen
- Centre for Molecular Medicine and Therapeutics at the BC Children’s Hospital, University of British Columbia, Vancouver, British Columbia, Canada
- Graduate Program in Bioinformatics, University of British Columbia, Vancouver, British Columbia, Canada
| | - David J Arenillas
- Centre for Molecular Medicine and Therapeutics at the BC Children’s Hospital, University of British Columbia, Vancouver, British Columbia, Canada
| | - Andrea J Korecki
- Centre for Molecular Medicine and Therapeutics at the BC Children’s Hospital, University of British Columbia, Vancouver, British Columbia, Canada
| | - Siu Ling Lam
- Centre for Molecular Medicine and Therapeutics at the BC Children’s Hospital, University of British Columbia, Vancouver, British Columbia, Canada
| | - Laurie L Molday
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, British Columbia, Canada
| | - Russell J Bonaguro
- Centre for Molecular Medicine and Therapeutics at the BC Children’s Hospital, University of British Columbia, Vancouver, British Columbia, Canada
| | - Michelle Zhou
- Centre for Molecular Medicine and Therapeutics at the BC Children’s Hospital, University of British Columbia, Vancouver, British Columbia, Canada
| | - Alice Y Chou
- Centre for Molecular Medicine and Therapeutics at the BC Children’s Hospital, University of British Columbia, Vancouver, British Columbia, Canada
| | - Anthony Mathelier
- Centre for Molecular Medicine and Therapeutics at the BC Children’s Hospital, University of British Columbia, Vancouver, British Columbia, Canada
- Department of Medical Genetics, University of British Columbia, Vancouver, British Columbia, Canada
| | - Sanford L Boye
- Department of Ophthalmology, College of Medicine, University of Florida, Gainesville, Florida, USA
| | - William W Hauswirth
- Department of Ophthalmology, College of Medicine, University of Florida, Gainesville, Florida, USA
| | - Robert S Molday
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, British Columbia, Canada
| | - Wyeth W Wasserman
- Centre for Molecular Medicine and Therapeutics at the BC Children’s Hospital, University of British Columbia, Vancouver, British Columbia, Canada
- Department of Medical Genetics, University of British Columbia, Vancouver, British Columbia, Canada
| | - Elizabeth M Simpson
- Centre for Molecular Medicine and Therapeutics at the BC Children’s Hospital, University of British Columbia, Vancouver, British Columbia, Canada
- Department of Medical Genetics, University of British Columbia, Vancouver, British Columbia, Canada
- Department of Psychiatry, University of British Columbia, Vancouver, British Columbia, Canada
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6
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Hou PS, Chuang CY, Kao CF, Chou SJ, Stone L, Ho HN, Chien CL, Kuo HC. LHX2 regulates the neural differentiation of human embryonic stem cells via transcriptional modulation of PAX6 and CER1. Nucleic Acids Res 2013; 41:7753-70. [PMID: 23804753 PMCID: PMC3763550 DOI: 10.1093/nar/gkt567] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
The LIM homeobox 2 transcription factor Lhx2 is known to control crucial aspects of neural development in various species. However, its function in human neural development is still elusive. Here, we demonstrate that LHX2 plays a critical role in human neural differentiation, using human embryonic stem cells (hESCs) as a model. In hESC-derived neural progenitors (hESC-NPs), LHX2 was found to be expressed before PAX6, and co-expressed with early neural markers. Conditional ectopic expression of LHX2 promoted neural differentiation, whereas disruption of LHX2 expression in hESCs significantly impaired neural differentiation. Furthermore, we have demonstrated that LHX2 regulates neural differentiation at two levels: first, it promotes expression of PAX6 by binding to its active enhancers, and second, it attenuates BMP and WNT signaling by promoting expression of the BMP and WNT antagonist Cerberus 1 gene (CER1), to inhibit non-neural differentiation. These findings indicate that LHX2 regulates the transcription of downstream intrinsic and extrinsic molecules that are essential for early neural differentiation in human.
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Affiliation(s)
- Pei-Shan Hou
- Department of Anatomy and Cell Biology, College of Medicine, National Taiwan University, Taipei 100, Taiwan, Genomics Research Center, Academia Sinica, Taipei 115, Taiwan, Institute of Cellular and Organismic Biology, Academia Sinica, Taipei 115, Taiwan, Division of Reproductive Endocrinology and Infertility, Department of Obstetrics and Gynecology, National Taiwan University Hospital, Taipei 100, Taiwan and Graduate Institute of Clinical Genomics, College of Medicine, National Taiwan University, Taipei 100, Taiwan
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7
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Davis-Silberman N, Kalich T, Oron-Karni V, Marquardt T, Kroeber M, Tamm ER, Ashery-Padan R. Genetic dissection of Pax6 dosage requirements in the developing mouse eye. Hum Mol Genet 2005; 14:2265-76. [PMID: 15987699 DOI: 10.1093/hmg/ddi231] [Citation(s) in RCA: 72] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Haploinsufficiency of the transcription factor Pax6/PAX6 has been implicated in a number of congenital eye disorders in humans and mice, such as aniridia and Small-eye, which affect the development and function of the lens, cornea, anterior eye segment and neuroretina. However, the widespread distribution of Pax6/PAX6 protein within the developing and adult eye preclude the identification and direct study of the ocular tissues affected by a reduction in Pax6/PAX6 dosage. Here, we employed Cre/loxP-mediated inactivation of a single Pax6 allele in either the lens/cornea or the distal optic cup to dissect the tissue-specific sensitivity to Pax6 haploinsufficiency. Exclusive inactivation of a single Pax6 allele in the lens recapitulates the Small-eye lens and corneal defects, while only mildly affects iris morphology in a non-cell-autonomous fashion. Conversely, selective inactivation of a single Pax6 allele in the distal optic cup revealed primarily cell-autonomous dosage requirements for proper iris differentiation, with no affects on either lens or corneal morphology. Pax6 dosage within the distal optic cup is found here to influence the number of progenitors destined for the anterior ocular structures, the timing of iris muscle-cell differentiation and iris stroma development. Taken together, we genetically dissected the complex mouse Small-eye phenotype, thereby pinpointing the underlying Pax6/PAX6 haploinsufficiency to autonomous dosage requirements within the developing iris and lens/cornea tissues.
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Affiliation(s)
- Noa Davis-Silberman
- Sackler Faculty of Medicine, Department of Human Genetics and Molecular Medicine, Tel Aviv University, Ramat Aviv, Tel Aviv 69978, Israel
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8
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Uchikawa M, Takemoto T, Kamachi Y, Kondoh H. Efficient identification of regulatory sequences in the chicken genome by a powerful combination of embryo electroporation and genome comparison. Mech Dev 2005; 121:1145-58. [PMID: 15296978 DOI: 10.1016/j.mod.2004.05.009] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2004] [Revised: 05/15/2004] [Accepted: 05/17/2004] [Indexed: 11/26/2022]
Abstract
Recently expanded knowledge of gene regulation clearly indicates that the regulatory sequences of a gene, usually identified as enhancers, are widely distributed in the gene locus, revising the classical view that they are clustered in the vicinity of genes. To identify regulatory sequences for Sox2 expression governing early neurogenesis, we scanned the 50-kb region of the chicken Sox2 locus for enhancer activity utilizing embryo electroporation, resulting in identification of a number of enhancers scattered throughout the analyzed genomic span. The 'pan-neural' Sox2 expression in early embryos is actually brought about by the composite activities of five separate enhancers with distinct spatio-temporal specificities. These and other functionally defined enhancers exactly correspond to extragenic sequence blocks that are conspicuously conserved between the chicken and mammalian genomes and that are embedded in sequences with a wide range of sequence conservation between humans and mice. The sequences conserved between amniotes and teleosts correspond to subregions of the enhancer subsets which presumably represent core motifs of the enhancers, and the limited conservation partly reflects divergent expression patterns of the gene. The phylogenic distance between the chicken and mammals appears optimal for identifying a battery of genetic regulatory elements as conserved sequence blocks, and chicken embryo electroporation facilitates functional characterization of these elements.
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Affiliation(s)
- Masanori Uchikawa
- Graduate School of Frontier Biosciences, Osaka University, 1-3 Yamadaoka, Suita, Osaka 565-0871, Japan
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9
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Abstract
The PAX6 gene is a paradigm for our understanding of the molecular genetics of mammalian eye development. Twelve years after its identification it is one of the most intensively studied genes, both in terms of its diverse and complex functions during oculogenesis and its role in an ever-increasing variety of human congenital eye malformations. The PAX6 field has benefited greatly from the continued input of clinicians, human geneticists and developmental biologists. This review summarizes the latest data on the PAX6 mutation spectrum and recent insights into Pax6 function from the mouse.
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Affiliation(s)
- Isabel M Hanson
- Medical Genetics Section, University of Edinburgh, Molecular Medicine Centre, Western General Hospital, Crewe Road, Edinburgh, EH4 2XU, United Kingdom.
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10
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Abstract
Life on earth has evolved on a photic carousel, spinning through alternating periods of light and darkness. This playful image belies the fact that only those organisms that learned how to benefit from the recurring features in their environment were allowed to ride on. This selection process has engendered many daily rhythms in our biosphere, most of which rely on the anticipatory power of an endogenously generated marker of phase: the biological clock. The basic mechanisms driving this remarkable device have been really tough to decode but are finally beginning to unravel as chronobiologists probe deeper and wider in and around the recently discovered gears of the clock. Like its chemical predecessors, biological circadian oscillators are characterized by interlaced positive and negative feedback loops, but with constants and variables carefully balanced to achieve an approximately 24h period. The loops at the heart of these biological oscillators are sustained by specific patterns of gene expression and precisely tuned posttranscriptional modifications. It follows that a molecular understanding of the biological clock hinges, in no small measure, on a better understanding of the cis-acting elements that bestow a given gene with its circadian properties. The present review summarizes what is known about these elements and what remains to be elucidated.
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Affiliation(s)
- Estela Muñoz
- Unit on Temporal Gene Expression, Laboratory of Cellular and Molecular Regulation, National Institute of Mental Health, National Institutes of Health, Bethesda, Maryland 20892, USA
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11
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Zhang X, Heaney S, Maas RL. Cre-loxp fate-mapping of Pax6 enhancer active retinal and pancreatic progenitors. Genesis 2003; 35:22-30. [PMID: 12481295 DOI: 10.1002/gene.10160] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Pax6 plays important roles in the control of ocular and pancreatic development. We identified a 450 bp Pax6 enhancer that contains two interacting sequences: a 274 bp fragment sufficient for expression in retinal progenitors and an adjacent 156 bp fragment required for expression in pancreatic progenitors. Since this enhancer is only transiently expressed during embryogenesis, a Cre-loxP fate-mapping strategy was used to investigate the developmental potential of these progenitors. Surprisingly, the labeled retinal precursors predominantly gave rise to horizontal cells, indicating a cell lineage role in horizontal cell differentiation. In the pancreas, all enhancer-specific cells were restricted to endocrine and ductal cell lineages. This result lends support to a model whereby Pax6-expressing progenitors contribute to the adult pancreatic islets and ducts. The progenitor cell-specificity of this enhancer will be useful in studies that require either cell-specific expression or conditional gene inactivation in these cell populations.
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Affiliation(s)
- Xin Zhang
- Division of Genetics, Department of Medicine, Brigham & Women's Hospital and Harvard Medical School, Boston, Massachusetts 02115, USA
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12
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Anderson TR, Hedlund E, Carpenter EM. Differential Pax6 promoter activity and transcript expression during forebrain development. Mech Dev 2002; 114:171-5. [PMID: 12175506 DOI: 10.1016/s0925-4773(02)00051-5] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Three different Pax6 promoters -- P0, P1, and P alpha -- show differential activity in the developing eye and spinal cord. To examine promoter usage during forebrain development, we performed in situ hybridization and reverse transcription-polymerase chain reaction to detect transcripts initiated from each promoter. Promoter-specific transcripts are expressed within subdomains of total Pax6 expression, but differ from one another in their spatial localization and expression over time. Additionally, we identified a novel P0-initiated transcript and detected a developmentally regulated antisense transcript.
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Affiliation(s)
- Tonya R Anderson
- UCLA Neuroscience IDP and Department of Psychiatry and Biobehavioral Science, UCLA School of Medicine, Los Angeles, CA 90024, USA
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13
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Griffin C, Kleinjan DA, Doe B, van Heyningen V. New 3' elements control Pax6 expression in the developing pretectum, neural retina and olfactory region. Mech Dev 2002; 112:89-100. [PMID: 11850181 DOI: 10.1016/s0925-4773(01)00646-3] [Citation(s) in RCA: 69] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Pax6 is a key transcriptional regulator in eye, olfactory system, forebrain, pituitary cerebellum, spinal cord and pancreas development. Alternative splicing, promoter usage and multiple enhancers regulate the complex Pax6 spatio-temporal expression pattern. Chromosomal rearrangements which abolish PAX6 gene expression have been characterised downstream of the coding region. Through evolutionary sequence comparison and transgenic reporter studies, we have identified a new Pax6 3' cis-regulatory region. This region, C1170 Box 123, contains three distinct modules of human-mouse sequence conservation, while only Box 1 is conserved to Fugu. Both the human and the orthologous Fugu sequence direct similar reporter gene expression in the developing pretectum, neural retina and olfactory region, indicating evolutionary conservation of Pax6 regulatory mechanisms despite the low level of overall sequence conservation.
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Affiliation(s)
- Caroline Griffin
- MRC Human Genetics Unit, Western General Hospital, Crewe Road, Edinburgh EH4 2XU, UK
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14
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Abstract
The Complement Receptor Type 2 (Cr2-145,CR2, CD21) is an important receptor in the innate and acquired immune response. CD21 is produced by B cells and follicular dendritic cells, where it binds cleavage products of the C3 complement protein. CD21 facilitates internalization of immune complexes by B cells to enhance antigen presentation. CD21, in association with CD19/CD81, also serves as a coaccessory activation complex with the B-cell antigen receptor, permitting a lower antigen concentration to achieve maximal B-cell activation. CD21 traps immune complexes on the surface of follicular dendritic cells and displays them to activated B cells in germinal centers. Much work has been conducted to determine the transcriptional control mechanisms dictating CD21 expression. Appropriate transcriptional control of the CD21 gene evidently requires the CD21 promoter, as well as intronic sequences with enhancer and suppressor functions. Chromatin structure has been implicated in regulating the coordination of CD21 promoter and intronic control sequences by regulating access to them by putative transcription factors. This review assesses the past and current research into CD21 transcriptional regulation and offers insight into future experimental directions.
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Affiliation(s)
- M D Zabel
- Division of Cell Biology and Immunology, Department of Pathology, University of Utah School of Medicine, Salt Lake City, UT 84132, USA.
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Dohrmann C, Gruss P, Lemaire L. Pax genes and the differentiation of hormone-producing endocrine cells in the pancreas. Mech Dev 2000; 92:47-54. [PMID: 10704887 DOI: 10.1016/s0925-4773(99)00324-x] [Citation(s) in RCA: 121] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Despite the pivotal role of the pancreas in hormonally-regulated pathways in the body, e.g. glucose homeostasis, the genetic mechanisms defining it have for many years remained largely enigmatic. After years out of the spotlight, pancreas development has once again come to centre stage. To a large extent, this is due to recent advances made through the detailed analysis of transgenic mice which have been engineered to carry mutations in specific developmental control genes. This review specifically focuses on the specification of the endocrine pancreas lineage and in particular on the role of the developmental control genes Pax4 and Pax6 in the generation of specific endocrine cell types. The comparison of various phenotypes of different mouse mutants affecting endocrine development supports a model in which Pax4 and Pax6 are required for the differentiation of certain endocrine cell lineages and implies a potential for acting at different levels of endocrine development.
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Affiliation(s)
- C Dohrmann
- DeveloGen AG, Rudolf-Wissell-Strasse 28, D-37079, Göttingen, Germany
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