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Yang H, Xu Y, Yuan Y, Liu X, Zhang J, Li J, Zhang R, Cao J, Cheng T, Liu C. Identification and function of the Pax gene Bmgsb in the silk gland of Bombyx mori. INSECT MOLECULAR BIOLOGY 2024; 33:173-184. [PMID: 38238257 DOI: 10.1111/imb.12886] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/20/2023] [Accepted: 11/29/2023] [Indexed: 05/08/2024]
Abstract
Paired box (Pax) genes are highly conserved throughout evolution, and the Pax protein is an important transcription factor of embryonic development. The Pax gene Bmgsb is expressed in the silk glands of silkworm, but its biological functions remain unclear. This study aimed to investigate the expression pattern of Bmgsb in the silk gland and explore its functions using RNA interference (RNAi). Here, we identified eight Pax genes in Bombyx mori. Phylogenetic analysis showed that the B. mori Pax genes were highly homologous to the Pax genes in other insects and highly evolutionarily conserved. The tissue expression profile showed that Bmgsb was expressed in the anterior silk gland and anterior part of the middle silk gland (AMSG). RNAi of Bmgsb resulted in defective development of the AMSG, and the larvae were mostly unable to cocoon in the wandering stage. RNA-seq analysis showed that the fibroin genes fib-l, fib-h and p25, cellular heat shock response-related genes and phenol oxidase genes were considerably upregulated upon Bmgsb knockdown. Furthermore, quantitative reverse transcription-PCR results showed that the fibroin genes and ubiquitin proteolytic enzyme-related genes were significantly upregulated in the AMSG after Bmgsb knockdown. This study provides a foundation for future research on the biological functions of B. mori Pax genes. In addition, it demonstrates the important roles of Bmgsb in the transcriptional regulation of fibroin genes and silk gland development.
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Affiliation(s)
- Hongguo Yang
- State Key Laboratory of Resource Insects, Southwest University, Chongqing, China
| | - Yongping Xu
- State Key Laboratory of Resource Insects, Southwest University, Chongqing, China
| | - Yutong Yuan
- State Key Laboratory of Resource Insects, Southwest University, Chongqing, China
| | - Xuebing Liu
- State Key Laboratory of Resource Insects, Southwest University, Chongqing, China
| | - Jikailang Zhang
- State Key Laboratory of Resource Insects, Southwest University, Chongqing, China
| | - Jiaojiao Li
- State Key Laboratory of Resource Insects, Southwest University, Chongqing, China
| | - Ran Zhang
- State Key Laboratory of Resource Insects, Southwest University, Chongqing, China
| | - Jun Cao
- State Key Laboratory of Resource Insects, Southwest University, Chongqing, China
| | - Tingcai Cheng
- State Key Laboratory of Resource Insects, Southwest University, Chongqing, China
- Cancer Center, Medical Research Institute, Southwest University, Chongqing, China
- Jinfeng Laboratory, Chongqing, China
| | - Chun Liu
- State Key Laboratory of Resource Insects, Southwest University, Chongqing, China
- Cancer Center, Medical Research Institute, Southwest University, Chongqing, China
- Jinfeng Laboratory, Chongqing, China
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Bollepogu Raja KK, Yeung K, Shim YK, Li Y, Chen R, Mardon G. A single cell genomics atlas of the Drosophila larval eye reveals distinct photoreceptor developmental timelines. Nat Commun 2023; 14:7205. [PMID: 37938573 PMCID: PMC10632452 DOI: 10.1038/s41467-023-43037-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2023] [Accepted: 10/30/2023] [Indexed: 11/09/2023] Open
Abstract
The Drosophila eye is a powerful model system to study the dynamics of cell differentiation, cell state transitions, cell maturation, and pattern formation. However, a high-resolution single cell genomics resource that accurately profiles all major cell types of the larval eye disc and their spatiotemporal relationships is lacking. Here, we report transcriptomic and chromatin accessibility data for all known cell types in the developing eye. Photoreceptors appear as strands of cells that represent their dynamic developmental timelines. As photoreceptor subtypes mature, they appear to assume a common transcriptomic profile that is dominated by genes involved in axon function. We identify cell type maturation genes, enhancers, and potential regulators, as well as genes with distinct R3 or R4 photoreceptor specific expression. Finally, we observe that the chromatin accessibility between cones and photoreceptors is distinct. These single cell genomics atlases will greatly enhance the power of the Drosophila eye as a model system.
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Affiliation(s)
- Komal Kumar Bollepogu Raja
- Department of Pathology and Immunology, Baylor College of Medicine, One Baylor Plaza, Houston, TX, 77030, USA
| | - Kelvin Yeung
- Department of Pathology and Immunology, Baylor College of Medicine, One Baylor Plaza, Houston, TX, 77030, USA
| | - Yoon-Kyung Shim
- Department of Pathology and Immunology, Baylor College of Medicine, One Baylor Plaza, Houston, TX, 77030, USA
| | - Yumei Li
- Department of Molecular and Human Genetics, Baylor College of Medicine, One Baylor Plaza, Houston, TX, 77030, USA
- Human Genome Sequencing Center, Baylor College of Medicine, One Baylor Plaza, Houston, TX, 77030, USA
| | - Rui Chen
- Department of Molecular and Human Genetics, Baylor College of Medicine, One Baylor Plaza, Houston, TX, 77030, USA
- Human Genome Sequencing Center, Baylor College of Medicine, One Baylor Plaza, Houston, TX, 77030, USA
| | - Graeme Mardon
- Department of Pathology and Immunology, Baylor College of Medicine, One Baylor Plaza, Houston, TX, 77030, USA.
- Department of Molecular and Human Genetics, Baylor College of Medicine, One Baylor Plaza, Houston, TX, 77030, USA.
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3
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Janeschik M, Schacht MI, Platten F, Turetzek N. It takes Two: Discovery of Spider Pax2 Duplicates Indicates Prominent Role in Chelicerate Central Nervous System, Eye, as Well as External Sense Organ Precursor Formation and Diversification After Neo- and Subfunctionalization. Front Ecol Evol 2022. [DOI: 10.3389/fevo.2022.810077] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Paired box genes are conserved across animals and encode transcription factors playing key roles in development, especially neurogenesis. Pax6 is a chief example for functional conservation required for eye development in most bilaterian lineages except chelicerates. Pax6 is ancestrally linked and was shown to have interchangeable functions with Pax2. Drosophila melanogaster Pax2 plays an important role in the development of sensory hairs across the whole body. In addition, it is required for the differentiation of compound eyes, making it a prime candidate to study the genetic basis of arthropod sense organ development and diversification, as well as the role of Pax genes in eye development. Interestingly, in previous studies identification of chelicerate Pax2 was either neglected or failed. Here we report the expression of two Pax2 orthologs in the common house spider Parasteatoda tepidariorum, a model organism for chelicerate development. The two Pax2 orthologs most likely arose as a consequence of a whole genome duplication in the last common ancestor of spiders and scorpions. Pax2.1 is expressed in the peripheral nervous system, including developing lateral eyes and external sensilla, as well as the ventral neuroectoderm of P. tepidariorum embryos. This not only hints at a conserved dual role of Pax2/5/8 orthologs in arthropod sense organ development but suggests that in chelicerates, Pax2 could have acquired the role usually played by Pax6. For the other paralog, Pt-Pax2.2, expression was detected in the brain, but not in the lateral eyes and the expression pattern associated with sensory hairs differs in timing, pattern, and strength. To achieve a broader phylogenetic sampling, we also studied the expression of both Pax2 genes in the haplogyne cellar spider Pholcus phalangioides. We found that the expression difference between paralogs is even more extreme in this species, since Pp-Pax2.2 shows an interesting expression pattern in the ventral neuroectoderm while the expression in the prosomal appendages is strictly mesodermal. This expression divergence indicates both sub- and neofunctionalization after Pax2 duplication in spiders and thus presents an opportunity to study the evolution of functional divergence after gene duplication and its impact on sense organ diversification.
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4
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Rass M, Gizler L, Bayersdorfer F, Irlbeck C, Schramm M, Schneuwly S. The Drosophila functional Smad suppressing element fuss, a homologue of the human Skor genes, retains pro-oncogenic properties of the Ski/Sno family. PLoS One 2022; 17:e0262360. [PMID: 35030229 PMCID: PMC8759651 DOI: 10.1371/journal.pone.0262360] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2021] [Accepted: 12/21/2021] [Indexed: 11/19/2022] Open
Abstract
Over the years Ski and Sno have been found to be involved in cancer progression e.g. in oesophageal squamous cell carcinoma, melanoma, oestrogen receptor-positive breast carcinoma, colorectal carcinoma, and leukaemia. Often, their prooncogenic features have been linked to their ability of inhibiting the anti-proliferative action of TGF-ß signalling. Recently, not only pro-oncogenic but also anti-oncogenic functions of Ski/Sno proteins have been revealed. Besides Ski and Sno, which are ubiquitously expressed other members of Ski/Sno proteins exist which show highly specific neuronal expression, the SKI Family Transcriptional Corepressors (Skor). Among others Skor1 and Skor2 are involved in the development of Purkinje neurons and a mutation of Skor1 has been found to be associated with restless legs syndrome. But neither Skor1 nor Skor2 have been reported to be involved in cancer progression. Using overexpression studies in the Drosophila eye imaginal disc, we analysed if the Drosophila Skor homologue Fuss has retained the potential to inhibit differentiation and induce increased proliferation. Fuss expressed in cells posterior to the morphogenetic furrow, impairs photoreceptor axon pathfinding and inhibits differentiation of accessory cells. However, if its expression is induced prior to eye differentiation, Fuss might inhibit the differentiating function of Dpp signalling and might maintain proliferative action of Wg signalling, which is reminiscent of the Ski/Sno protein function in cancer.
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Affiliation(s)
- Mathias Rass
- Department of Developmental Biology, Institute of Zoology, University of Regensburg, Regensburg, Germany
- * E-mail:
| | - Laura Gizler
- Department of Developmental Biology, Institute of Zoology, University of Regensburg, Regensburg, Germany
| | - Florian Bayersdorfer
- Department of Developmental Biology, Institute of Zoology, University of Regensburg, Regensburg, Germany
| | - Christoph Irlbeck
- Department of Developmental Biology, Institute of Zoology, University of Regensburg, Regensburg, Germany
| | - Matthias Schramm
- Department of Developmental Biology, Institute of Zoology, University of Regensburg, Regensburg, Germany
| | - Stephan Schneuwly
- Department of Developmental Biology, Institute of Zoology, University of Regensburg, Regensburg, Germany
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5
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Avetisyan A, Glatt Y, Cohen M, Timerman Y, Aspis N, Nachman A, Halachmi N, Preger-Ben Noon E, Salzberg A. Delilah, prospero, and D-Pax2 constitute a gene regulatory network essential for the development of functional proprioceptors. eLife 2021; 10:70833. [PMID: 34964712 PMCID: PMC8716109 DOI: 10.7554/elife.70833] [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: 05/31/2021] [Accepted: 12/03/2021] [Indexed: 12/03/2022] Open
Abstract
Coordinated animal locomotion depends on the development of functional proprioceptors. While early cell-fate determination processes are well characterized, little is known about the terminal differentiation of cells within the proprioceptive lineage and the genetic networks that control them. In this work we describe a gene regulatory network consisting of three transcription factors–Prospero (Pros), D-Pax2, and Delilah (Dei)–that dictates two alternative differentiation programs within the proprioceptive lineage in Drosophila. We show that D-Pax2 and Pros control the differentiation of cap versus scolopale cells in the chordotonal organ lineage by, respectively, activating and repressing the transcription of dei. Normally, D-Pax2 activates the expression of dei in the cap cell but is unable to do so in the scolopale cell where Pros is co-expressed. We further show that D-Pax2 and Pros exert their effects on dei transcription via a 262 bp chordotonal-specific enhancer in which two D-Pax2- and three Pros-binding sites were identified experimentally. When this enhancer was removed from the fly genome, the cap- and ligament-specific expression of dei was lost, resulting in loss of chordotonal organ functionality and defective larval locomotion. Thus, coordinated larval locomotion depends on the activity of a dei enhancer that integrates both activating and repressive inputs for the generation of a functional proprioceptive organ.
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Affiliation(s)
- Adel Avetisyan
- Department of Genetics and Developmental Biology, The Rappaport Faculty of Medicine and Research Institute, Technion-Israel Institute of Technology, Haifa, Israel
| | - Yael Glatt
- Department of Genetics and Developmental Biology, The Rappaport Faculty of Medicine and Research Institute, Technion-Israel Institute of Technology, Haifa, Israel
| | - Maya Cohen
- Department of Genetics and Developmental Biology, The Rappaport Faculty of Medicine and Research Institute, Technion-Israel Institute of Technology, Haifa, Israel
| | - Yael Timerman
- Department of Genetics and Developmental Biology, The Rappaport Faculty of Medicine and Research Institute, Technion-Israel Institute of Technology, Haifa, Israel
| | - Nitay Aspis
- Department of Genetics and Developmental Biology, The Rappaport Faculty of Medicine and Research Institute, Technion-Israel Institute of Technology, Haifa, Israel
| | - Atalya Nachman
- Department of Genetics and Developmental Biology, The Rappaport Faculty of Medicine and Research Institute, Technion-Israel Institute of Technology, Haifa, Israel
| | - Naomi Halachmi
- Department of Genetics and Developmental Biology, The Rappaport Faculty of Medicine and Research Institute, Technion-Israel Institute of Technology, Haifa, Israel
| | - Ella Preger-Ben Noon
- Department of Genetics and Developmental Biology, The Rappaport Faculty of Medicine and Research Institute, Technion-Israel Institute of Technology, Haifa, Israel
| | - Adi Salzberg
- Department of Genetics and Developmental Biology, The Rappaport Faculty of Medicine and Research Institute, Technion-Israel Institute of Technology, Haifa, Israel
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6
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Ray-Jones H, Spivakov M. Transcriptional enhancers and their communication with gene promoters. Cell Mol Life Sci 2021; 78:6453-6485. [PMID: 34414474 PMCID: PMC8558291 DOI: 10.1007/s00018-021-03903-w] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2021] [Revised: 07/08/2021] [Accepted: 07/19/2021] [Indexed: 12/13/2022]
Abstract
Transcriptional enhancers play a key role in the initiation and maintenance of gene expression programmes, particularly in metazoa. How these elements control their target genes in the right place and time is one of the most pertinent questions in functional genomics, with wide implications for most areas of biology. Here, we synthesise classic and recent evidence on the regulatory logic of enhancers, including the principles of enhancer organisation, factors that facilitate and delimit enhancer-promoter communication, and the joint effects of multiple enhancers. We show how modern approaches building on classic insights have begun to unravel the complexity of enhancer-promoter relationships, paving the way towards a quantitative understanding of gene control.
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Affiliation(s)
- Helen Ray-Jones
- MRC London Institute of Medical Sciences, London, W12 0NN, UK
- Institute of Clinical Sciences, Faculty of Medicine, Imperial College, London, W12 0NN, UK
| | - Mikhail Spivakov
- MRC London Institute of Medical Sciences, London, W12 0NN, UK.
- Institute of Clinical Sciences, Faculty of Medicine, Imperial College, London, W12 0NN, UK.
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7
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Sex peptide receptor-regulated polyandry modulates the balance of pre- and post-copulatory sexual selection in Drosophila. Nat Commun 2019; 10:283. [PMID: 30655522 PMCID: PMC6336784 DOI: 10.1038/s41467-018-08113-w] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2018] [Accepted: 12/17/2018] [Indexed: 01/15/2023] Open
Abstract
Polyandry prolongs sexual selection on males by forcing ejaculates to compete for fertilisation. Recent theory predicts that increasing polyandry may weaken pre-copulatory sexual selection on males and increase the relative importance of post-copulatory sexual selection, but experimental tests of this prediction are lacking. Here, we manipulate the polyandry levels in groups of Drosophila melanogaster by deletion of the female sex peptide receptor. We show that groups in which the sex-peptide-receptor is absent in females (SPR-) have higher polyandry, and – as a result – weaker pre-copulatory sexual selection on male mating success, compared to controls. Post-copulatory selection on male paternity share is relatively more important in SPR- groups, where males gain additional paternity by mating repeatedly with the same females. These results provide experimental evidence that elevated polyandry weakens pre-copulatory sexual selection on males, shifts selection to post-copulatory events, and that the sex peptide pathway can play a key role in modulating this process in Drosophila. Theory predicts that mating systems influence the relative strength of sexual selection before and after mating. Here, Morimoto and colleagues demonstrate that higher polyandry weakens precopulatory while strengthening post-copulatory sexual selection on males in Drosophila melanogaster.
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8
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Gaspar P, Almudi I, Nunes MDS, McGregor AP. Human eye conditions: insights from the fly eye. Hum Genet 2018; 138:973-991. [PMID: 30386938 DOI: 10.1007/s00439-018-1948-2] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2018] [Accepted: 10/20/2018] [Indexed: 12/22/2022]
Abstract
The fruit fly Drosophila melanogaster has served as an excellent model to study and understand the genetics of many human diseases from cancer to neurodegeneration. Studying the regulation of growth, determination and differentiation of the compound eyes of this fly, in particular, have provided key insights into a wide range of diseases. Here we review the regulation of the development of fly eyes in light of shared aspects with human eye development. We also show how understanding conserved regulatory pathways in eye development together with the application of tools for genetic screening and functional analyses makes Drosophila a powerful model to diagnose and characterize the genetics underlying many human eye conditions, such as aniridia and retinitis pigmentosa. This further emphasizes the importance and vast potential of basic research to underpin applied research including identifying and treating the genetic basis of human diseases.
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Affiliation(s)
- Pedro Gaspar
- Department of Biological and Medical Sciences, Oxford Brookes University, Gipsy Lane, Oxford, OX3 0BP, UK
| | - Isabel Almudi
- Centro Andaluz de Biología del Desarrollo, CSIC/ Universidad Pablo de Olavide, Carretera de Utrera Km1, 41013, Sevilla, Spain
| | - Maria D S Nunes
- Department of Biological and Medical Sciences, Oxford Brookes University, Gipsy Lane, Oxford, OX3 0BP, UK
| | - Alistair P McGregor
- Department of Biological and Medical Sciences, Oxford Brookes University, Gipsy Lane, Oxford, OX3 0BP, UK.
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9
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Hassan A, Timerman Y, Hamdan R, Sela N, Avetisyan A, Halachmi N, Salzberg A. An RNAi Screen Identifies New Genes Required for Normal Morphogenesis of Larval Chordotonal Organs. G3 (BETHESDA, MD.) 2018; 8:1871-1884. [PMID: 29678948 PMCID: PMC5982817 DOI: 10.1534/g3.118.200218] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/06/2018] [Accepted: 04/19/2018] [Indexed: 01/10/2023]
Abstract
The proprioceptive chordotonal organs (ChO) of a fly larva respond to mechanical stimuli generated by muscle contractions and consequent deformations of the cuticle. The ability of the ChO to sense the relative displacement of its epidermal attachment sites likely depends on the correct mechanical properties of the accessory (cap and ligament) and attachment cells that connect the sensory unit (neuron and scolopale cell) to the cuticle. The genetic programs dictating the development of ChO cells with unique morphologies and mechanical properties are largely unknown. Here we describe an RNAi screen that focused on the ChO's accessory and attachment cells and was performed in 2nd instar larvae to allow for phenotypic analysis of ChOs that had already experienced mechanical stresses during larval growth. Nearly one thousand strains carrying RNAi constructs targeting more than 500 candidate genes were screened for their effects on ChO morphogenesis. The screen identified 31 candidate genes whose knockdown within the ChO lineage disrupted various aspects of cell fate determination, cell differentiation, cellular morphogenesis and cell-cell attachment. Most interestingly, one phenotypic group consisted of genes that affected the response of specific ChO cell types to developmental organ stretching, leading to abnormal pattern of cell elongation. The 'cell elongation' group included the transcription factors Delilah and Stripe, implicating them for the first time in regulating the response of ChO cells to developmental stretching forces. Other genes found to affect the pattern of ChO cell elongation, such as αTub85E, β1Tub56D, Tbce, CCT8, mys, Rac1 and shot, represent putative effectors that link between cell-fate determinants and the realization of cell-specific mechanical properties.
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Affiliation(s)
- Abeer Hassan
- Department of Genetics and Developmental Biology, The Rappaport Faculty of Medicine and Research Institute, Technion-Israel Institute of Technology, Haifa 3109601, Israel
| | - Yael Timerman
- Department of Genetics and Developmental Biology, The Rappaport Faculty of Medicine and Research Institute, Technion-Israel Institute of Technology, Haifa 3109601, Israel
| | - Rana Hamdan
- Department of Genetics and Developmental Biology, The Rappaport Faculty of Medicine and Research Institute, Technion-Israel Institute of Technology, Haifa 3109601, Israel
| | - Nitzan Sela
- Department of Genetics and Developmental Biology, The Rappaport Faculty of Medicine and Research Institute, Technion-Israel Institute of Technology, Haifa 3109601, Israel
| | - Adel Avetisyan
- Department of Genetics and Developmental Biology, The Rappaport Faculty of Medicine and Research Institute, Technion-Israel Institute of Technology, Haifa 3109601, Israel
| | - Naomi Halachmi
- Department of Genetics and Developmental Biology, The Rappaport Faculty of Medicine and Research Institute, Technion-Israel Institute of Technology, Haifa 3109601, Israel
| | - Adi Salzberg
- Department of Genetics and Developmental Biology, The Rappaport Faculty of Medicine and Research Institute, Technion-Israel Institute of Technology, Haifa 3109601, Israel
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10
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Dalal CK, Johnson AD. How transcription circuits explore alternative architectures while maintaining overall circuit output. Genes Dev 2017; 31:1397-1405. [PMID: 28860157 PMCID: PMC5588923 DOI: 10.1101/gad.303362.117] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
This review by Dalal and Johnson focuses on the evolutionary rewiring of transcription regulators and the conservation of patterns of gene expression. They describe how preservation of gene expression patterns in the wake of extensive rewiring is a general feature of transcription circuit evolution. Transcription regulators bind to cis-regulatory sequences and thereby control the expression of target genes. While transcription regulators and the target genes that they regulate are often deeply conserved across species, the connections between the two change extensively over evolutionary timescales. In this review, we discuss case studies where, despite this extensive evolutionary rewiring, the resulting patterns of gene expression are preserved. We also discuss in silico models that reach the same general conclusions and provide additional insights into how this process occurs. Together, these approaches make a strong case that the preservation of gene expression patterns in the wake of extensive rewiring is a general feature of transcription circuit evolution.
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Affiliation(s)
- Chiraj K Dalal
- Department of Microbiology and Immunology, University of California at San Francisco, San Francisco, California 94158, USA
| | - Alexander D Johnson
- Department of Microbiology and Immunology, University of California at San Francisco, San Francisco, California 94158, USA.,Department of Biochemistry and Biophysics, University of California at San Francisco, San Francisco, California 94158, USA
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11
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Differential effects of male nutrient balance on pre- and post-copulatory traits, and consequences for female reproduction in Drosophila melanogaster. Sci Rep 2016; 6:27673. [PMID: 27270223 PMCID: PMC4897696 DOI: 10.1038/srep27673] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2016] [Accepted: 05/24/2016] [Indexed: 12/15/2022] Open
Abstract
Male fitness depends on the expression of costly traits involved in obtaining mates (pre-copulatory) and fertilization (post-copulatory). However, very little is known about the nutrient requirements for these traits and whether males compromise their diet to maximize one trait at the expense of another. Here we used Nutritional Geometry to investigate macronutrient requirements for pre- and post-copulatory traits in Drosophila, when males were the first or second to mate with females. We found no significant effects of male diet on sperm competitiveness. However, although males self-regulate their macronutrient intake at a protein-to-carbohydrate ratio ("P:C ratio") of 1:1.5, this ratio does not coincide with their optima for several key reproductive traits: both the short-term (~24 hr) rate of offspring production after a female's first mating, as well as the total offspring number sired when males were second to mate were maximized at a P:C ratio of 1:9, whereas male attractiveness (latency to mate), were maximised at a P:C ratio of 1:1. These results suggest a compromised optimum diet, and no single diet that simultaneously maximizes all male reproductive traits. The protein intake of first males also negatively affected female offspring production following remating, suggesting a long-term intersexual effect of male nutrition.
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12
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Developmental Environment Effects on Sexual Selection in Male and Female Drosophila melanogaster. PLoS One 2016; 11:e0154468. [PMID: 27167120 PMCID: PMC4864243 DOI: 10.1371/journal.pone.0154468] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2015] [Accepted: 04/13/2016] [Indexed: 11/19/2022] Open
Abstract
The developmental environment can potentially alter the adult social environment and influence traits targeted by sexual selection such as body size. In this study, we manipulated larval density in male and female Drosophila melanogaster, which results in distinct adult size phenotypes–high (low) densities for small (large) adults–and measured sexual selection in experimental groups consisting of adult males and females from high, low, or a mixture of low and high larval densities. Overall, large adult females (those reared at low larval density) had more matings, more mates and produced more offspring than small females (those reared at high larval density). The number of offspring produced by females was positively associated with their number of mates (i.e. there was a positive female Bateman gradient) in social groups where female size was experimentally varied, likely due to the covariance between female productivity and mating rate. For males, we found evidence that the larval environment affected the relative importance of sexual selection via mate number (Bateman gradients), mate productivity, paternity share, and their covariances. Mate number and mate productivity were significantly reduced for small males in social environments where males were of mixed sizes, versus social environments where all males were small, suggesting that social heterogeneity altered selection on this subset of males. Males are commonly assumed to benefit from mating with large females, but in contrast to expectations we found that in groups where both the male and female size varied, males did not gain more offspring per mating with large females. Collectively, our results indicate sex-specific effects of the developmental environment on the operation of sexual selection, via both the phenotype of individuals, and the phenotype of their competitors and mates.
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13
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Connahs H, Rhen T, Simmons RB. Transcriptome analysis of the painted lady butterfly, Vanessa cardui during wing color pattern development. BMC Genomics 2016; 17:270. [PMID: 27030049 PMCID: PMC4815134 DOI: 10.1186/s12864-016-2586-5] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2015] [Accepted: 03/14/2016] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Butterfly wing color patterns are an important model system for understanding the evolution and development of morphological diversity and animal pigmentation. Wing color patterns develop from a complex network composed of highly conserved patterning genes and pigmentation pathways. Patterning genes are involved in regulating pigment synthesis however the temporal expression dynamics of these interacting networks is poorly understood. Here, we employ next generation sequencing to examine expression patterns of the gene network underlying wing development in the nymphalid butterfly, Vanessa cardui. RESULTS We identified 9, 376 differentially expressed transcripts during wing color pattern development, including genes involved in patterning, pigmentation and gene regulation. Differential expression of these genes was highest at the pre-ommochrome stage compared to early pupal and late melanin stages. Overall, an increasing number of genes were down-regulated during the progression of wing development. We observed dynamic expression patterns of a large number of pigment genes from the ommochrome, melanin and also pteridine pathways, including contrasting patterns of expression for paralogs of the yellow gene family. Surprisingly, many patterning genes previously associated with butterfly pattern elements were not significantly up-regulated at any time during pupation, although many other transcription factors were differentially expressed. Several genes involved in Notch signaling were significantly up-regulated during the pre-ommochrome stage including slow border cells, bunched and pebbles; the function of these genes in the development of butterfly wings is currently unknown. Many genes involved in ecdysone signaling were also significantly up-regulated during early pupal and late melanin stages and exhibited opposing patterns of expression relative to the ecdysone receptor. Finally, a comparison across four butterfly transcriptomes revealed 28 transcripts common to all four species that have no known homologs in other metazoans. CONCLUSIONS This study provides a comprehensive list of differentially expressed transcripts during wing development, revealing potential candidate genes that may be involved in regulating butterfly wing patterns. Some differentially expressed genes have no known homologs possibly representing genes unique to butterflies. Results from this study also indicate that development of nymphalid wing patterns may arise not only from melanin and ommochrome pigments but also the pteridine pigment pathway.
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Affiliation(s)
- Heidi Connahs
- Biology Department, University of North Dakota, Grand Forks, ND, USA. .,Department of Biological Sciences, National University of Singapore, Singapore, Singapore.
| | - Turk Rhen
- Biology Department, University of North Dakota, Grand Forks, ND, USA
| | - Rebecca B Simmons
- Biology Department, University of North Dakota, Grand Forks, ND, USA
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14
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Sajuthi A, Carrillo-Zazueta B, Hu B, Wang A, Brodnansky L, Mayberry J, Rivera AS. Sexually dimorphic gene expression in the lateral eyes of Euphilomedes carcharodonta (Ostracoda, Pancrustacea). EvoDevo 2015; 6:34. [PMID: 26561519 PMCID: PMC4641368 DOI: 10.1186/s13227-015-0026-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2015] [Accepted: 09/22/2015] [Indexed: 12/29/2022] Open
Abstract
Background The evolution and development of sexual dimorphism illuminates a central question in biology: How do similar genomes produce different phenotypes? In an XX/XO system especially the state of a sexually dimorphic trait is determined by differences in gene expression, as there are no additional genetic loci in either sex. Here, we examine the XX/XO ostracod crustacean species Euphilomedes carcharodonta. This species exhibits radical sexual dimorphism of their lateral eyes, females have only a tiny simple lateral eye while males have elaborate ommatidial eyes. Results We find that males express three of nine eye-development gene homologs at significantly higher levels during juvenile eye development, compared to females. We also find that most eye-development genes examined are pleiotropic, with high expression levels during embryonic development as well as during juvenile eye development. Later, in adults, we find that phototransduction genes are expressed at higher levels in males than in females, as we might expect when comparing ommatidial to simple eyes. Conclusions We show here that expression changes of a handful of developmental genes may underlie the radical difference in a dimorphic character. This work gives an important point of comparison for studying eye evolution and development in the Pancrustacea. Electronic supplementary material The online version of this article (doi:10.1186/s13227-015-0026-2) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Andrea Sajuthi
- Department of Biological Sciences, University of the Pacific, Stockton, CA USA ; Stritch School of Medicine, Loyola University, Chicago, IL USA
| | - Brenna Carrillo-Zazueta
- Department of Biological Sciences, University of the Pacific, Stockton, CA USA ; Dugoni School of Dentistry, University of the Pacific, San Francisco, CA USA
| | - Briana Hu
- Department of Biological Sciences, University of the Pacific, Stockton, CA USA
| | - Anita Wang
- Department of Biological Sciences, University of the Pacific, Stockton, CA USA ; Thomas J. Long School of Pharmacy and Health Sciences, University of the Pacific, Stockton, CA USA
| | - Logan Brodnansky
- Department of Biological Sciences, University of the Pacific, Stockton, CA USA ; Thomas J. Long School of Pharmacy and Health Sciences, University of the Pacific, Stockton, CA USA
| | - John Mayberry
- Department of Biological Sciences, University of the Pacific, Stockton, CA USA
| | - Ajna S Rivera
- Department of Biological Sciences, University of the Pacific, Stockton, CA USA
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15
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Franke FA, Schumann I, Hering L, Mayer G. Phylogenetic analysis and expression patterns of Pax genes in the onychophoran Euperipatoides rowelli reveal a novel bilaterian Pax subfamily. Evol Dev 2015; 17:3-20. [PMID: 25627710 DOI: 10.1111/ede.12110] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Pax family genes encode a class of transcription factors that regulate various developmental processes. To shed light on the evolutionary history of these genes in Panarthropoda (Onychophora + Tardigrada + Arthropoda), we analyzed the Pax repertoire in the embryonic and adult transcriptomes of the onychophoran Euperipatoides rowelli. Our data revealed homologs of all five major bilaterian Pax subfamilies in this species, including Pax2/5/8, Pax4/6, Pox-neuro, Pax1/9/Pox-meso, and Pax3/7. In addition, we identified a new Pax member, pax-α, which does not fall into any other known Pax subfamily but instead clusters in the heterogenic Pax-α/β clade containing deuterostome, ecdysozoan, and lophotrochozoan gene sequences. These findings suggest that the last common bilaterian ancestor possessed six rather than five Pax genes, which have been retained in the panarthropod lineage. The expression data of Pax orthologs in the onychophoran embryo revealed distinctive patterns, some of which might be related to their ancestral roles in the last common panarthropod ancestor, whereas others might be specific to the onychophoran lineage. The derived roles include, for example, an involvement of pax2/5/8, pox-neuro, and pax3/7 in onychophoran nephridiogenesis, and an additional function of pax2/5/8 in the formation of the ventral and preventral organs. Furthermore, our transcriptomic analyses suggest that at least some Pax genes, including pax6 and pax-α, are expressed in the adult onychophoran head, although the corresponding functions remain to be clarified. The remarkable diversity of the Pax expression patterns highlights the functional and evolutionary plasticity of these genes in panarthropods.
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Affiliation(s)
- Franziska Anni Franke
- Animal Evolution & Development, , Institute of Biology, University of Leipzig, Talstraße 33, D-04103, Leipzig, Germany
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16
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Bosch JA, Tran NH, Hariharan IK. CoinFLP: a system for efficient mosaic screening and for visualizing clonal boundaries in Drosophila. Development 2015; 142:597-606. [PMID: 25605786 PMCID: PMC4302991 DOI: 10.1242/dev.114603] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2014] [Accepted: 12/05/2014] [Indexed: 01/12/2023]
Abstract
Screens in mosaic Drosophila tissues that use chemical mutagenesis have identified many regulators of growth and patterning. Many of the mutant phenotypes observed were contingent upon the presence of both wild-type and mutant cells in the same tissue. More recently, large collections of RNAi lines or cDNAs expressed under Gal4/UAS control have been used to alter gene expression uniformly in specific tissues. However, these newer approaches are not easily combined with the efficient generation of genetic mosaics. The CoinFLP system described here enables mosaic screens in the context of gene knockdown or overexpression by automatically generating a reliable ratio of mutant to wild-type tissue in a developmentally controlled manner. CoinFLP-Gal4 generates mosaic tissues composed of clones of which only a subset expresses Gal4. CoinFLP-LexGAD/Gal4 generates tissues composed of clones that express either Gal4 or LexGAD, thus allowing the study of interactions between different types of genetically manipulated cells. By combining CoinFLP-LexGAD/Gal4 with the split-GFP system GRASP, boundaries between genetically distinct cell populations can be visualized at high resolution.
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Affiliation(s)
- Justin A Bosch
- Department of Molecular and Cell Biology, University of California, Berkeley 361 LSA, Berkeley, CA 94720-3200, USA
| | - Ngoc Han Tran
- Department of Molecular and Cell Biology, University of California, Berkeley 361 LSA, Berkeley, CA 94720-3200, USA
| | - Iswar K Hariharan
- Department of Molecular and Cell Biology, University of California, Berkeley 361 LSA, Berkeley, CA 94720-3200, USA
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17
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Backfisch B, Veedin Rajan VB, Fischer RM, Lohs C, Arboleda E, Tessmar-Raible K, Raible F. Stable transgenesis in the marine annelid Platynereis dumerilii sheds new light on photoreceptor evolution. Proc Natl Acad Sci U S A 2013; 110:193-8. [PMID: 23284166 PMCID: PMC3538230 DOI: 10.1073/pnas.1209657109] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Research in eye evolution has mostly focused on eyes residing in the head. In contrast, noncephalic light sensors are far less understood and rather regarded as evolutionary innovations. We established stable transgenesis in the annelid Platynereis, a reference species for evolutionary and developmental comparisons. EGFP controlled by cis-regulatory elements of r-opsin, a characteristic marker for rhabdomeric photoreceptors, faithfully recapitulates known r-opsin expression in the adult eyes, and marks a pair of pigment-associated frontolateral eyelets in the brain. Unexpectedly, transgenic animals revealed an additional series of photoreceptors in the ventral nerve cord as well as photoreceptors that are located in each pair of the segmental dorsal appendages (notopodia) and project into the ventral nerve cord. Consistent with a photosensory function of these noncephalic cells, decapitated animals display a clear photoavoidance response. Molecular analysis of the receptors suggests that they differentiate independent of pax6, a gene involved in early eye development of many metazoans, and that the ventral cells may share origins with the Hesse organs in the amphioxus neural tube. Finally, expression analysis of opn4×-2 and opn4m-2, two zebrafish orthologs of Platynereis r-opsin, reveals that these genes share expression in the neuromasts, known mechanoreceptors of the lateral line peripheral nervous system. Together, this establishes that noncephalic photoreceptors are more widespread than assumed, and may even reflect more ancient aspects of sensory systems. Our study marks significant advance for the understanding of photoreceptor cell (PRC) evolution and development and for Platynereis as a functional lophotrochozoan model system.
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Affiliation(s)
| | | | - Ruth M. Fischer
- Max F. Perutz Laboratories, Department of Microbiology, Immunobiology, and Genetics, University of Vienna, A-1030 Vienna, Austria
| | | | | | - Kristin Tessmar-Raible
- Max F. Perutz Laboratories, Department of Microbiology, Immunobiology, and Genetics, University of Vienna, A-1030 Vienna, Austria
| | - Florian Raible
- Max F. Perutz Laboratories, Department of Microbiology, Immunobiology, and Genetics, University of Vienna, A-1030 Vienna, Austria
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18
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Abstract
Since the discovery of a single white-eyed male in a population of red eyed flies over 100 years ago (Morgan, 1910), the compound eye of the fruit fly, Drosophila melanogaster, has been a favorite experimental system for identifying genes that regulate various aspects of development. For example, a fair amount of what we know today about enzymatic pathways and vesicular transport is due to the discovery and subsequent characterization of eye color mutants such as white. Likewise, our present day understanding of organogenesis has been aided considerably by studies of mutations, such as eyeless, that either reduce or eliminate the compound eyes. But by far the phenotype that has provided levers into the greatest number of experimental fields has been the humble "rough" eye. The fly eye is composed of several hundred unit-eyes that are also called ommatidia. These unit eyes are packed into a hexagonal array of remarkable precision. The structure of the eye is so precise that it has been compared with that of a crystal (Ready et al., 1976). Even the slightest perturbations to the structure of the ommatidium can be visually detected by light or electron microscopy. The cause for this is two-fold: (1) any defect that affects the hexagonal geometry of a single ommatidium can and will disrupt the positioning of surrounding unit eyes thereby propagating structural flaws and (2) disruptions in genes that govern the development of even a single cell within an ommatidium will affect all unit eyes. In both cases, the effect is the visual magnification of even the smallest imperfection. Studies of rough eye mutants have provided key insights into the areas of cell fate specification, lateral inhibition, signal transduction, transcription factor networks, planar cell polarity, cell proliferation, and programmed cell death just to name a few. This review will attempt to summarize the key steps that are required to assemble each ommatidium.
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Affiliation(s)
- Justin P Kumar
- Department of Biology, Indiana University, Bloomington, Indiana 47405, USA.
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19
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Li-Kroeger D, Cook TA, Gebelein B. Integration of an abdominal Hox complex with Pax2 yields cell-specific EGF secretion from Drosophila sensory precursor cells. Development 2012; 139:1611-9. [PMID: 22438572 DOI: 10.1242/dev.077842] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Cis-regulatory modules (CRMs) ensure specific developmental outcomes by mediating both proper spatiotemporal gene expression patterns and appropriate transcriptional levels. In Drosophila, the precise transcriptional control of the serine protease rhomboid regulates EGF signaling to specify distinct cell types. Recently, we identified a CRM that activates rhomboid expression and thereby EGF secretion from a subset of abdominal sensory organ precursor cells (SOPs) to induce an appropriate number of lipid-processing cells called oenocytes. Here, we use scanning mutagenesis coupled with reporter assays, biochemistry and genetics to dissect the transcriptional mechanisms regulating SOP-specific rhomboid activation. Our results show that proper spatial activity of the rhomboid CRM is dependent upon direct integration of the abdomen-specific Hox factor Abdominal-A and the SOP-restricted Pax2 factor. In addition, we show that the Extradenticle and Homothorax Hox co-factors are differentially integrated on the rhomboid CRM by abdominal versus thoracic Hox proteins in the presence of Pax2. Last, we show that Abdominal-A uses both Pax2-dependent and Pax2-independent mechanisms to stimulate rhomboid CRM activity to induce proper oenocyte numbers. Thus, these data demonstrate how a CRM integrates Hox and neural transcriptional inputs to regulate the appropriate spatial pattern and levels of EGF secretion to specify an essential cell fate.
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Affiliation(s)
- David Li-Kroeger
- Division of Developmental Biology, Cincinnati Children's Hospital, 3333 Burnet Avenue, MLC 7007, Cincinnati, OH 45229, USA
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20
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Parrilla M, Lillo C, Herrero-Turrión MJ, Arévalo R, Aijón J, Lara JM, Velasco A. Characterization of Pax2 expression in the goldfish optic nerve head during retina regeneration. PLoS One 2012; 7:e32348. [PMID: 22384226 PMCID: PMC3288081 DOI: 10.1371/journal.pone.0032348] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2011] [Accepted: 01/26/2012] [Indexed: 01/09/2023] Open
Abstract
The Pax2 transcription factor plays a crucial role in axon-guidance and astrocyte differentiation in the optic nerve head (ONH) during vertebrate visual system development. However, little is known about its function during regeneration. The fish visual system is in continuous growth and can regenerate. Müller cells and astrocytes of the retina and ONH play an important role in these processes. We demonstrate that pax2a in goldfish is highly conserved and at least two pax2a transcripts are expressed in the optic nerve. Moreover, we show two different astrocyte populations in goldfish: Pax2+ astrocytes located in the ONH and S100+ astrocytes distributed throughout the retina and the ONH. After peripheral growth zone (PGZ) cryolesion, both Pax2+ and S100+ astrocytes have different responses. At 7 days after injury the number of Pax2+ cells is reduced and coincides with the absence of young axons. In contrast, there is an increase of S100+ astrocytes in the retina surrounding the ONH and S100+ processes in the ONH. At 15 days post injury, the PGZ starts to regenerate and the number of S100+ astrocytes increases in this region. Moreover, the regenerating axons reach the ONH and the pax2a gene expression levels and the number of Pax2+ cells increase. At the same time, S100+/GFAP+/GS+ astrocytes located in the posterior ONH react strongly. In the course of the regeneration, Müller cell vitreal processes surrounding the ONH are primarily disorganized and later increase in number. During the whole regenerative process we detect a source of Pax2+/PCNA+ astrocytes surrounding the posterior ONH. We demonstrate that pax2a expression and the Pax2+ astrocyte population in the ONH are modified during the PGZ regeneration, suggesting that they could play an important role in this process.
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Affiliation(s)
| | | | | | | | | | | | - Almudena Velasco
- Institute of Neuroscience of Castilla y Leon, University of Salamanca, Salamanca, Spain
- * E-mail:
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21
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Barolo S. Shadow enhancers: frequently asked questions about distributed cis-regulatory information and enhancer redundancy. Bioessays 2012; 34:135-41. [PMID: 22083793 PMCID: PMC3517143 DOI: 10.1002/bies.201100121] [Citation(s) in RCA: 115] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
This paper, in the form of a frequently asked questions page (FAQ), addresses outstanding questions about "shadow enhancers", quasi-redundant cis-regulatory elements, and their proposed roles in transcriptional control. Questions include: What exactly are shadow enhancers? How many genes have shadow/redundant/distributed enhancers? How redundant are these elements? What is the function of distributed enhancers? How modular are enhancers? Is it useful to study a single enhancer in isolation? In addition, a revised definition of "shadow enhancers" is proposed, and possible mechanisms of shadow enhancer function and evolution are discussed.
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Affiliation(s)
- Scott Barolo
- Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, MI, USA.
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22
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Swanson CI, Schwimmer DB, Barolo S. Rapid evolutionary rewiring of a structurally constrained eye enhancer. Curr Biol 2011; 21:1186-96. [PMID: 21737276 DOI: 10.1016/j.cub.2011.05.056] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2010] [Revised: 04/18/2011] [Accepted: 05/27/2011] [Indexed: 12/20/2022]
Abstract
BACKGROUND Enhancers are genomic cis-regulatory sequences that integrate spatiotemporal signals to control gene expression. Enhancer activity depends on the combination of bound transcription factors as well as-in some cases-the arrangement and spacing of binding sites for these factors. Here, we examine evolutionary changes to the sequence and structure of sparkling, a Notch/EGFR/Runx-regulated enhancer that activates the dPax2 gene in cone cells of the developing Drosophila eye. RESULTS Despite functional and structural constraints on its sequence, sparkling has undergone major reorganization in its recent evolutionary history. Our data suggest that the relative strengths of the various regulatory inputs into sparkling change rapidly over evolutionary time, such that reduced input from some factors is compensated by increased input from different regulators. These gains and losses are at least partly responsible for the changes in enhancer structure that we observe. Furthermore, stereotypical spatial relationships between certain binding sites ("grammar elements") can be identified in all sparkling orthologs-although the sites themselves are often recently derived. We also find that low binding affinity for the Notch-regulated transcription factor Su(H), a conserved property of sparkling, is required to prevent ectopic responses to Notch in noncone cells. CONCLUSIONS Rapid DNA sequence turnover does not imply either the absence of critical cis-regulatory information or the absence of structural rules. Our findings demonstrate that even a severely constrained cis-regulatory sequence can be significantly rewired over a short evolutionary timescale.
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Affiliation(s)
- Christina I Swanson
- Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, MI 48109-2200, USA
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23
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Johnson SA, Harmon KJ, Smiley SG, Still FM, Kavaler J. Discrete regulatory regions control early and late expression of D-Pax2 during external sensory organ development. Dev Dyn 2011; 240:1769-78. [PMID: 21644243 DOI: 10.1002/dvdy.22672] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/10/2011] [Indexed: 01/04/2023] Open
Abstract
The transcription factor D-Pax2 is required for the correct differentiation of several cell types in Drosophila sensory systems. While the regulation of its expression in the developing eye has been well studied, little is known about the mechanisms by which the dynamic pattern of D-Pax2 expression in the external sensory organs is achieved. Here we demonstrate that early activation of D-Pax2 in the sensory organ lineage and its maintenance in the trichogen and thecogen cells are governed by separate enhancers. Furthermore, the initial activation is controlled in part by proneural proteins whereas the later maintenance expression is regulated by a positive feedback loop.
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Affiliation(s)
- Seth A Johnson
- Department of Biology, Colby College, Waterville, Maine, USA
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24
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Baker NE, Firth LC. Retinal determination genes function along with cell-cell signals to regulate Drosophila eye development: examples of multi-layered regulation by master regulators. Bioessays 2011; 33:538-46. [PMID: 21607995 DOI: 10.1002/bies.201000131] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
It is thought that retinal determination (RD) gene products define the response made to cell-cell signals in the field of eye development by binding to enhancers of genes that are also regulated by cell-cell signaling pathways. In Drosophila, RD genes, including eyeless, teashirt, eyes absent, dachsous, and sine oculis, are required for normal eye development and can induce ectopic eyes when mis-expressed. Characterization of the enhancers responsible for eye expression of the hedgehog, shaven, and atonal genes, as well as the dynamics of RD gene expression themselves, now suggest a multilayered network whereby transcriptional regulation by either RD genes or cell-cell signaling pathways can sometimes be indirect and mediated by other transcription factor intermediates. In this updated view of the interaction between extracellular information and cell intrinsic programs during development, regulation of individual genes might sometimes be several steps removed from either the RD genes or the cell-cell signaling pathways that nevertheless govern their expression.
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Affiliation(s)
- Nicholas E Baker
- Department of Genetics, Albert Einstein College of Medicine, Bronx, NY, USA; Department of Opthalmology and Visual Sciences, Albert Einstein College of Medicine, Bronx, NY, USA.
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25
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Swanson CI, Evans NC, Barolo S. Structural rules and complex regulatory circuitry constrain expression of a Notch- and EGFR-regulated eye enhancer. Dev Cell 2010; 18:359-70. [PMID: 20230745 PMCID: PMC2847355 DOI: 10.1016/j.devcel.2009.12.026] [Citation(s) in RCA: 121] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2008] [Revised: 09/27/2009] [Accepted: 12/27/2009] [Indexed: 01/13/2023]
Abstract
Enhancers integrate spatiotemporal information to generate precise patterns of gene expression. How complex is the regulatory logic of a typical developmental enhancer, and how important is its internal organization? Here, we examine in detail the structure and function of sparkling, a Notch- and EGFR/MAPK-regulated, cone cell-specific enhancer of the Drosophila Pax2 gene, in vivo. In addition to its 12 previously identified protein-binding sites, sparkling is densely populated with previously unmapped regulatory sequences, which interact in complex ways to control gene expression. One segment is essential for activation at a distance, yet dispensable for other activation functions and for cell type patterning. Unexpectedly, rearranging sparkling's regulatory sites converts it into a robust photoreceptor-specific enhancer. Our results show that a single combination of regulatory inputs can encode multiple outputs, and suggest that the enhancer's organization determines the correct expression pattern by facilitating certain short-range regulatory interactions at the expense of others.
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MESH Headings
- Animals
- Animals, Genetically Modified
- Base Sequence
- Binding Sites/genetics
- DNA/genetics
- DNA-Binding Proteins/genetics
- DNA-Binding Proteins/metabolism
- Drosophila/genetics
- Drosophila/growth & development
- Drosophila/metabolism
- Drosophila Proteins/genetics
- Drosophila Proteins/metabolism
- Drosophila melanogaster/genetics
- Drosophila melanogaster/growth & development
- Drosophila melanogaster/metabolism
- Enhancer Elements, Genetic
- ErbB Receptors/genetics
- ErbB Receptors/metabolism
- Evolution, Molecular
- Eye/growth & development
- Eye/metabolism
- Eye Proteins/genetics
- Eye Proteins/metabolism
- Gene Expression Regulation, Developmental
- Genes, Insect
- MAP Kinase Signaling System
- Molecular Sequence Data
- Mutagenesis
- PAX2 Transcription Factor/genetics
- PAX2 Transcription Factor/metabolism
- Photoreceptor Cells, Invertebrate/cytology
- Photoreceptor Cells, Invertebrate/metabolism
- Receptors, Invertebrate Peptide/genetics
- Receptors, Invertebrate Peptide/metabolism
- Receptors, Notch/genetics
- Receptors, Notch/metabolism
- Sequence Homology, Nucleic Acid
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Affiliation(s)
- Christina I. Swanson
- Department of Cell & Developmental Biology, University of Michigan Medical School, Ann Arbor, MI 48109-2200, USA
| | - Nicole C. Evans
- Department of Cell & Developmental Biology, University of Michigan Medical School, Ann Arbor, MI 48109-2200, USA
| | - Scott Barolo
- Department of Cell & Developmental Biology, University of Michigan Medical School, Ann Arbor, MI 48109-2200, USA
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26
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Abstract
Whole genome duplication events are thought to have substantially contributed to organismal complexity, largely via divergent transcriptional regulation. Members of the vertebrate PAX2, PAX5 and PAX8 gene subfamily derived from an ancient class of paired box genes and arose from such whole genome duplication events. These genes are critical in establishing the midbrain-hindbrain boundary, specifying interneuron populations and for eye, ear and kidney development. Also PAX2 has adopted a unique role in pancreas development, whilst PAX5 is essential for early B-cell differentiation. The contribution of PAX258 genes to their collective role has diverged across paralogues and the animal lineages, resulting in a complex wealth of literature. It is now timely to provide a comprehensive comparative overview of these genes and their ancient and divergent roles. We also discuss their fundamental place within gene regulatory networks and the likely influence of cis-regulatory elements over their differential roles during early animal development.
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Affiliation(s)
- Debbie K Goode
- Queen Mary, University of London, School of Biological and Chemical Sciences, London, United Kingdom
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27
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Keller RG, Desplan C, Rosenberg MI. Identification and characterization of Nasonia Pax genes. INSECT MOLECULAR BIOLOGY 2010; 19 Suppl 1:109-120. [PMID: 20167022 PMCID: PMC2852259 DOI: 10.1111/j.1365-2583.2009.00921.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Pax genes are a group of critical developmental transcriptional regulators in both invertebrates and vertebrates, characterized by the presence of a paired DNA-binding domain. Pax proteins also often contain an octapeptide motif and a C-terminal homeodomain. The genome of Nasonia vitripennis (Hymenoptera) has recently become available, and analysis of this genome alongside Apis mellifera allowed us to contribute to the phylogeny of this gene family in insects. Nasonia, a parasitic wasp, has independently evolved a similar mode of development to that of the well-studied Drosophila, making it an excellent model system for comparative studies of developmental gene networks. We report the characterization of the seven Nasonia Pax genes. We describe their genomic organization, and the embryonic expression of three of them, and uncover wider conservation of the octapeptide motif than previously described.
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Affiliation(s)
- R G Keller
- Center for Developmental Genetics, Department of Biology, New York University, New York, NY 10003, USA
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Dziedzic K, Heaphy J, Prescott H, Kavaler J. The transcription factor D-Pax2 regulates crystallin production during eye development in Drosophila melanogaster. Dev Dyn 2010; 238:2530-9. [PMID: 19718746 DOI: 10.1002/dvdy.22082] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
The generation of a functioning Drosophila eye requires the coordinated differentiation of multiple cell types and the morphogenesis of eye-specific structures. Here we show that D-Pax2 plays a significant role in lens development through regulation of the Crystallin gene and because Crystallin is also expressed in D-Pax2(+) cells in the external sensory organs. Loss of D-Pax2 function leads to loss of Crystallin expression in both eyes and bristles. A 2.3 kilobase (kb) upstream region of the Crystallin gene can drive GFP expression in the eye and is dependent on D-Pax2. In addition, D-Pax2 binds to an evolutionarily conserved site in this region that, by itself, is sufficient to drive GFP expression in the eye. However, mutation of this site does not greatly affect the regulatory region's function. The data indicate that D-Pax2 acts to promote lens development by controlling the production of the major protein component of the lens. Whether this control is direct or indirect remains unresolved.
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Shi Y, Noll M. Determination of cell fates in the R7 equivalence group of the Drosophila eye by the concerted regulation of D-Pax2 and TTK88. Dev Biol 2009; 331:68-77. [PMID: 19406115 DOI: 10.1016/j.ydbio.2009.04.026] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2009] [Revised: 04/06/2009] [Accepted: 04/22/2009] [Indexed: 11/30/2022]
Abstract
In the developing Drosophila eye, the precursors of the neuronal photoreceptor cells R1/R6/R7 and non-neuronal cone cells share the same developmental potential and constitute the R7 equivalence group. It is not clear how cells of this group elaborate their distinct fates. Here we show that both TTK88 and D-Pax2 play decisive roles in cone cell development and act in concert to transform developing R1/R6/R7 into cone cells: while TTK88 blocks neuronal development, D-Pax2 promotes cone cell specification. In addition, ectopic TTK88 in R cells induces apoptosis, which is suppressed by ectopic D-Pax2. We further demonstrate that Phyllopod (Phyl), previously shown to promote the neuronal fate in R1/R6/R7 by targeting TTK for degradation, also inhibits D-Pax2 transcription to prevent cone cell specification. Thus, the fates of R1/R6/R7 and cone cells are determined by a dual mechanism that coordinately activates one fate while inhibiting the other.
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Affiliation(s)
- Yandong Shi
- Institute for Molecular Biology, University of Zürich, Winterthurerstrasse 190, CH-8057 Zürich, Switzerland
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30
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Johnson LA, Zhao Y, Golden K, Barolo S. Reverse-engineering a transcriptional enhancer: a case study in Drosophila. Tissue Eng Part A 2009; 14:1549-59. [PMID: 18687053 DOI: 10.1089/ten.tea.2008.0074] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Enhancers, or cis-regulatory elements, are the principal determinants of spatiotemporal patterning of gene expression. For reasons of clinical and research utility, it is desirable to build customized enhancers that drive novel gene expression patterns, but currently, we largely rely on "found" genomic elements. Synthetic enhancers, assembled from transcription factor binding sites taken from natural signal-regulated enhancers, generally fail to behave like their wild-type counterparts when placed in transgenic animals, suggesting that important aspects of enhancer function are still unexplored. As a step toward the creation of a truly synthetic regulatory element, we have undertaken an extensive structure-function study of an enhancer of the Drosophila decapentaplegic (dpp) gene that drives expression in the developing visceral mesoderm (VM). Although considerable past efforts have been made to dissect the dppVM enhancer, transgenic experiments presented here indicate that its activity cannot be explained by the known regulators alone. dppVM contains multiple, previously uncharacterized, regulatory sites, some of which exhibit functional redundancy. The results presented here suggest that even the best-studied enhancers must be further dissected before they can be fully understood, and before faithful synthetic elements based on them can be created. Implications for developmental genetics, mathematical modeling, and therapeutic applications are discussed.
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Affiliation(s)
- Lisa A Johnson
- Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, Michigan, USA
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31
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Bassham S, Cañestro C, Postlethwait JH. Evolution of developmental roles of Pax2/5/8 paralogs after independent duplication in urochordate and vertebrate lineages. BMC Biol 2008; 6:35. [PMID: 18721460 PMCID: PMC2532684 DOI: 10.1186/1741-7007-6-35] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2008] [Accepted: 08/22/2008] [Indexed: 12/02/2022] Open
Abstract
Background Gene duplication provides opportunities for lineage diversification and evolution of developmental novelties. Duplicated genes generally either disappear by accumulation of mutations (nonfunctionalization), or are preserved either by the origin of positively selected functions in one or both duplicates (neofunctionalization), or by the partitioning of original gene subfunctions between the duplicates (subfunctionalization). The Pax2/5/8 family of important developmental regulators has undergone parallel expansion among chordate groups. After the divergence of urochordate and vertebrate lineages, two rounds of independent gene duplications resulted in the Pax2, Pax5, and Pax8 genes of most vertebrates (the sister group of the urochordates), and an additional duplication provided the pax2a and pax2b duplicates in teleost fish. Separate from the vertebrate genome expansions, a duplication also created two Pax2/5/8 genes in the common ancestor of ascidian and larvacean urochordates. Results To better understand mechanisms underlying the evolution of duplicated genes, we investigated, in the larvacean urochordate Oikopleura dioica, the embryonic gene expression patterns of Pax2/5/8 paralogs. We compared the larvacean and ascidian expression patterns to infer modular subfunctions present in the single pre-duplication Pax2/5/8 gene of stem urochordates, and we compared vertebrate and urochordate expression to infer the suite of Pax2/5/8 gene subfunctions in the common ancestor of olfactores (vertebrates + urochordates). Expression pattern differences of larvacean and ascidian Pax2/5/8 orthologs in the endostyle, pharynx and hindgut suggest that some ancestral gene functions have been partitioned differently to the duplicates in the two urochordate lineages. Novel expression in the larvacean heart may have resulted from the neofunctionalization of a Pax2/5/8 gene in the urochordates. Expression of larvacean Pax2/5/8 in the endostyle, in sites of epithelial remodeling, and in sensory tissues evokes like functions of Pax2, Pax5 and Pax8 in vertebrate embryos, and may indicate ancient origins for these functions in the chordate common ancestor. Conclusion Comparative analysis of expression patterns of chordate Pax2/5/8 duplicates, rooted on the single-copy Pax2/5/8 gene of amphioxus, whose lineage diverged basally among chordates, provides new insights into the evolution and development of the heart, thyroid, pharynx, stomodeum and placodes in chordates; supports the controversial conclusion that the atrial siphon of ascidians and the otic placode in vertebrates are homologous; and backs the notion that Pax2/5/8 functioned in ancestral chordates to engineer epithelial fusions and perforations, including gill slit openings.
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Affiliation(s)
- Susan Bassham
- Center for Ecology and Evolutionary Biology, University of Oregon, Eugene, OR 97403, USA.
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32
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Doroquez DB, Rebay I. Signal integration during development: mechanisms of EGFR and Notch pathway function and cross-talk. Crit Rev Biochem Mol Biol 2007; 41:339-85. [PMID: 17092823 DOI: 10.1080/10409230600914344] [Citation(s) in RCA: 107] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Metazoan development relies on a highly regulated network of interactions between conserved signal transduction pathways to coordinate all aspects of cell fate specification, differentiation, and growth. In this review, we discuss the intricate interplay between the epidermal growth factor receptor (EGFR; Drosophila EGFR/DER) and the Notch signaling pathways as a paradigm for signal integration during development. First, we describe the current state of understanding of the molecular architecture of the EGFR and Notch signaling pathways that has resulted from synergistic studies in vertebrate, invertebrate, and cultured cell model systems. Then, focusing specifically on the Drosophila eye, we discuss how cooperative, sequential, and antagonistic relationships between these pathways mediate the spatially and temporally regulated processes that generate this sensory organ. The common themes underlying the coordination of the EGFR and Notch pathways appear to be broadly conserved and should, therefore, be directly applicable to elucidating mechanisms of information integration and signaling specificity in vertebrate systems.
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Affiliation(s)
- David B Doroquez
- Department of Biology, Whitehead Institute for Biomedical Research, Massachusetts Institute of Technology, Cambridge, MA, USA
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33
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34
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Regulation of Development of Wing Venation in Drosophila melanogaster by a Network of Signalling Pathways. Russ J Dev Biol 2005. [DOI: 10.1007/s11174-005-0051-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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35
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Wech I, Nagel AC. Mutations in rugose promote cell type-specific apoptosis in the Drosophila eye. Cell Death Differ 2005; 12:145-52. [PMID: 15647755 DOI: 10.1038/sj.cdd.4401538] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
RUGOSE (RG): encodes an A kinase anchor protein and was isolated as a genetic interactor of the Notch and epidermal growth factor receptor (EGFR) pathways during eye development in Drosophila. rg mutants display a small, rough eye phenotype primarily caused by the loss of cone cells. Here we show that the basis of this phenotype is cell type-specific apoptosis rather than transformation and hence can be rescued by reduction of proapoptotic signals. Moreover, a nearly complete rescue is observed by an increased Notch signal suggesting an antiapoptotic function of Notch in this developmental context. Cone cell loss in rg mutants is accompanied by enhanced Jun N-terminal kinase activity and, concomitantly, by a reduction of EGFR signalling activity. Together, these findings support the idea that rg plays an important role in the integration of different signals required for the exact regulation of cone cell development and survival.
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Affiliation(s)
- I Wech
- Institute of Genetics (240), University of Hohenheim, Garbenstr. 30, 70599 Stuttgart, Germany
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36
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Adamson AL, Wright N, LaJeunesse DR. Modeling early Epstein-Barr virus infection in Drosophila melanogaster: the BZLF1 protein. Genetics 2005; 171:1125-35. [PMID: 16079238 PMCID: PMC1456816 DOI: 10.1534/genetics.105.042572] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Epstein-Barr virus (EBV) is the causative agent of infectious mononucleosis and is associated with several forms of cancer, including lymphomas and nasopharyngeal carcinoma. The EBV immediate-early protein BZLF1 functions as a transcriptional activator of EBV early gene expression and is essential for the viral transition between latent and lytic replication. In addition to its role in the EBV life cycle, BZLF1 (Z) also has profound effects upon the host cellular environment, including disruption of cell cycle regulation, signal transduction pathways, and transcription. In an effort to understand the nature of Z interactions with the host cellular environment, we have developed a Drosophila model of early EBV infection, where we have expressed Z in the Drosophila eye. Using this system, we have identified a highly conserved interaction between the Epstein-Barr virus Z protein and shaven, a Drosophila homolog of the human Pax2/5/8 family of genes. Pax5 is a well-characterized human gene involved with B-cell development. The B-cell-specific Pax5 also promotes the transcription of EBV latent genes from the EBV Wp promoter. Our work clearly demonstrates that the Drosophila system is an appropriate and powerful tool for identifying the underlying genetic networks involved in human infectious disease.
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Affiliation(s)
- Amy L Adamson
- Department of Biology, University of North Carolina, Greensboro, North Carolina, 27402, USA.
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37
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Kozmik Z. Pax genes in eye development and evolution. Curr Opin Genet Dev 2005; 15:430-8. [PMID: 15950457 DOI: 10.1016/j.gde.2005.05.001] [Citation(s) in RCA: 104] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2005] [Accepted: 05/23/2005] [Indexed: 10/25/2022]
Abstract
Animal eyes with widely different anatomical designs have long been thought to arise independently, multiple times during evolution. This view was challenged about a decade ago by the landmark discoveries that Pax6, a highly conserved transcription factor, plays a key role in eye morphogenesis in both flies and mammals. Since then, more evidence has emerged in favour of the redeployment of Pax6 and some other developmental control genes within the genetic program underlying eye formation throughout the animal kingdom. Recent work has indicated that other members of the Pax gene family play a pivotal role in eye morphogenesis. The Eye gone gene regulates eye growth in Drosophila, whereas the PaxB gene is implicated in visual system development in jellyfish, the most basal organism possessing eyes.
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Affiliation(s)
- Zbynek Kozmik
- Institute of Molecular Genetics, Videnska 1083, 142 20 Praha 4, Czech Republic.
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38
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Hadrys T, DeSalle R, Sagasser S, Fischer N, Schierwater B. The Trichoplax PaxB Gene: A Putative Proto-PaxA/B/C Gene Predating the Origin of Nerve and Sensory Cells. Mol Biol Evol 2005; 22:1569-78. [PMID: 15858210 DOI: 10.1093/molbev/msi150] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Pax genes play key regulatory roles in embryonic and sensory organ development in metazoans but their evolution and ancestral functions remain widely unresolved. We have isolated a Pax gene from Placozoa, beside Porifera the only metazoan phylum that completely lacks nerve and sensory cells or organs. These simplest known metazoans also lack any kind of symmetry, organs, extracellular matrix, basal lamina, muscle cells, and main body axis. The isolated Pax gene from Trichoplax adhaerens harbors a paired domain, an octapeptide, and a full-length homeodomain. It displays structural features not only of PaxB and Pax2/5/8-like genes but also of PaxC and Pax6 genes. Conserved splice sites between Placozoa, Cnidaria, and triploblasts, mark the ancient origin of intron structures. Phylogenetic analyses demonstrate that the Trichoplax PaxB gene, TriPaxB, is basal not only to all other known PaxB genes but also to PaxA and PaxC genes and their relatives in triploblasts (namely Pax2/5/8, Pax4/6, and Poxneuro). TriPaxB is expressed in distinct cell patches near the outer edge of the animal body, where undifferentiated and possibly multipotent cells are found. This expression pattern indicates a developmental role in cell-type specification and/or differentiation, probably in specifying-determining fiber cells, which are regarded as proto-neural/muscle cells in Trichoplax. While PaxB, Pax2/5/8, and Pax6 genes have been linked to nerve cell and sensory system/organ development in virtually all animals investigated so far, our study suggests that Pax genes predate the origin of nerve and sensory cells.
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39
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Affiliation(s)
- Hamed Jafar-Nejad
- Department of Molecular and Human Genetics, Howard Hughes Medical Institute, Houston, TX 77030, USA
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40
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Frankfort BJ, Pepple KL, Mamlouk M, Rose MF, Mardon G. Senseless is required for pupal retinal development inDrosophila. Genesis 2004; 38:182-94. [PMID: 15083519 DOI: 10.1002/gene.20018] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Drosophila sensory organs are specified by a family of proneural genes which induce the expression of several common targets. One such target is senseless, which encodes a zinc finger transcription factor. We analyzed the function of senseless during pupal retinal development and found that senseless is required for recruitment of both cone and pigment cells, the pupal-derived ommatidial support cells. We also found that Senseless is expressed in neural precursors shortly after the larval-pupal transition and is both necessary and sufficient for interommatidial bristle development. Furthermore, senseless is the primary target of achaete and scute during interommatidial bristle development. We also identified several differences between the development of interommatidial bristles and other macrochaete. In particular, EGFR signaling is not required for interommatidial bristle development, nor is positive feedback regulation of proneural genes by senseless. A model for interommatidial bristle specification is presented.
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Affiliation(s)
- Benjamin J Frankfort
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas 77030, USA
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41
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Kozmik Z, Daube M, Frei E, Norman B, Kos L, Dishaw LJ, Noll M, Piatigorsky J. Role of Pax genes in eye evolution: a cnidarian PaxB gene uniting Pax2 and Pax6 functions. Dev Cell 2003; 5:773-85. [PMID: 14602077 DOI: 10.1016/s1534-5807(03)00325-3] [Citation(s) in RCA: 85] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
PaxB from Tripedalia cystophora, a cubomedusan jellyfish possessing complex eyes (ocelli), was characterized. PaxB, the only Pax gene found in this cnidarian, is expressed in the larva, retina, lens, and statocyst. PaxB contains a Pax2/5/8-type paired domain and octapeptide, but a Pax6 prd-type homeodomain. Pax2/5/8-like properties of PaxB include a DNA binding specificity of the paired domain, activation and inhibitory domains, and the ability to rescue spa(pol), a Drosophila Pax2 eye mutant. Like Pax6, PaxB activates jellyfish crystallin and Drosophila rhodopsin rh6 promoters and induces small ectopic eyes in Drosophila. Pax6 has been considered a "master" control gene for eye development. Our data suggest that the ancestor of jellyfish PaxB, a PaxB-like protein, was the primordial Pax protein in eye evolution and that Pax6-like genes evolved in triploblasts after separation from Cnidaria, raising the possibility that cnidarian and sophisticated triploblastic eyes arose independently.
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Affiliation(s)
- Zbynek Kozmik
- Laboratory of Molecular and Developmental Biology, National Eye Institute, National Institutes of Health, Bethesda, MD 20892, USA
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42
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O'Brien EK, Degnan BM. Expression of Pax258 in the gastropod statocyst: insights into the antiquity of metazoan geosensory organs. Evol Dev 2003; 5:572-8. [PMID: 14984039 DOI: 10.1046/j.1525-142x.2003.03062.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Most animals have sensory systems that allow them to balance and orient relative to the pull of gravity. Structures responsible for these functions range from very simple statocysts found in many aquatic invertebrates to the complex inner ear of mammals. Previous studies suggest that the specialized mechanosensory structures responsible for balance in vertebrates and insects may be homologous based on the requirement and expression of group II Pax genes (i.e., Pax-2/5/8 genes). Here we report the expression of a Pax-258 gene in the statocysts and other chemosensory and mechanosensory cells during the development of the gastropod mollusk Haliotis asinina, a member of the Lophotrochozoa. Based on the phylogenetic distribution of geosensory systems and the consistent expression of Pax-258 in the cells that form these systems, we propose that Pax-258, along with POU-III and -IV genes, has an ancient and conserved role in the formation of structures responsible for balance and geotaxis in eumetazoans.
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Affiliation(s)
- Elizabeth K O'Brien
- Department of Zoology and Entomology, University of Queensland, Brisbane, Qld 4072, Australia
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43
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Tang CY, Sun YH. Use of mini-white as a reporter gene to screen for GAL4 insertions with spatially restricted expression pattern in the developing eye in drosophila. Genesis 2002; 34:39-45. [PMID: 12324945 DOI: 10.1002/gene.10135] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Chiou-Yang Tang
- Institute of Molecular Biology, Academia Sinica, Nankang, Taipei, Taiwan, Republic of China
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44
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Affiliation(s)
- Raghavendra Nagaraj
- Department of Molecular, Cell and Developmental Biology, Golecular Biology Institute, University of California, Los Angeles, California 90095, USA
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45
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Flores GV, Duan H, Yan H, Nagaraj R, Fu W, Zou Y, Noll M, Banerjee U. Combinatorial signaling in the specification of unique cell fates. Cell 2000; 103:75-85. [PMID: 11051549 DOI: 10.1016/s0092-8674(00)00106-9] [Citation(s) in RCA: 202] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
How multifunctional signals combine to specify unique cell fates during pattern formation is not well understood. Here, we demonstrate that together with the transcription factor Lozenge, the nuclear effectors of the EGFR and Notch signaling pathways directly regulate D-Pax2 transcription in cone cells of the Drosophila eye disc. Moreover, the specificity of D-Pax2 expression can be altered upon genetic manipulation of these inputs. Thus, a relatively small number of temporally and spatially controlled signals received by a set of pluripotent cells can create the unique combinations of activated transcription factors required to regulate target genes and ultimately specify distinct cell fates within this group. We expect that similar mechanisms may specify pattern formation in vertebrate developmental systems that involve intercellular communication.
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Affiliation(s)
- G V Flores
- Department of Molecular, Cell, and Developmental Biology and Molecular Biology Institute, University of California at Los Angeles 90095, USA
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46
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Locke J, Podemski L, Aippersbach N, Kemp H, Hodgetts R. A physical map of the polytenized region (101EF-102F) of chromosome 4 in Drosophila melanogaster. Genetics 2000; 155:1175-83. [PMID: 10880479 PMCID: PMC1461150 DOI: 10.1093/genetics/155.3.1175] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Chromosome 4, the smallest autosome ( approximately 5 Mb in length) in Drosophila melanogaster contains two major regions. The centromeric domain ( approximately 4 Mb) is heterochromatic and consists primarily of short, satellite repeats. The remaining approximately 1.2 Mb, which constitutes the banded region (101E-102F) on salivary gland polytene chromosomes and contains the identified genes, is the region mapped in this study. Chromosome walking was hindered by the abundance of moderately repeated sequences dispersed along the chromosome, so we used many entry points to recover overlapping cosmid and BAC clones. In situ hybridization of probes from the two ends of the map to polytene chromosomes confirmed that the cloned region had spanned the 101E-102F interval. Our BAC clones comprised three contigs; one gap was positioned distally in 102EF and the other was located proximally at 102B. Twenty-three genes, representing about half of our revised estimate of the total number of genes on chromosome 4, were positioned on the BAC contigs. A minimal tiling set of the clones we have mapped will facilitate both the assembly of the DNA sequence of the chromosome and a functional analysis of its genes.
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Affiliation(s)
- J Locke
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta T6G 2E9, Canada.
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47
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Riley BB, Chiang M, Farmer L, Heck R. The deltaA gene of zebrafish mediates lateral inhibition of hair cells in the inner ear and is regulated by pax2.1. Development 1999; 126:5669-78. [PMID: 10572043 DOI: 10.1242/dev.126.24.5669] [Citation(s) in RCA: 93] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Recent studies of inner ear development suggest that hair cells and support cells arise within a common equivalence group by cell-cell interactions mediated by Delta and Notch proteins. We have extended these studies by analyzing the effects of a mutant allele of the zebrafish deltaA gene, deltaA(dx2), which encodes a dominant-negative protein. deltaA(dx2/dx2)homozygous mutants develop with a 5- to 6-fold excess of hair cells and a severe deficiency of support cells. In addition, deltaA(dx2/dx2) mutants show an increased number of cells expressing pax2.1 in regions where hair cells are normally produced. Immunohistological analysis of wild-type and deltaA(dx2/dx2) mutant embryos confirmed that pax2.1 is expressed during the initial stages of hair cell differentiation and is later maintained at high levels in mature hair cells. In contrast, pax2.1 is not expressed in support cells. To address the function of pax2.1, we analyzed hair cell differentiation in no isthmus mutant embryos, which are deficient for pax2.1 function. no isthmus mutant embryos develop with approximately twice the normal number of hair cells. This neurogenic defect correlates with reduced levels of expression of deltaA and deltaD in the hair cells in no isthmus mutants. Analysis of deltaA(dx2/dx2); no isthmus double mutants showed that no isthmus suppresses the deltaA(dx2) phenotype, probably by reducing levels of the dominant-negative mutant protein. This interpretation was supported by analysis of T(msxB)(b220), a deletion that removes the deltaA locus. Reducing the dose of deltaA(dx2) by generating deltaA(dx2)/T(msxB)(b220)trans-heterozygotes weakens the neurogenic effects of deltaA(dx2), whereas T(msxB)(b220) enhances the neurogenic defects of no isthmus. mind bomb, another strong neurogenic mutation that may disrupt reception of Delta signals, causes a 10-fold increase in hair cell production and is epistatic to both no isthmus and deltaA(dx2). These data indicate that deltaA expressed by hair cells normally prevents adjacent cells from adopting the same cell fate, and that pax2.1 is required for normal levels of Delta-mediated lateral inhibition.
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Affiliation(s)
- B B Riley
- Biology Department, Texas A&M University, College Station, TX 77843-3258, USA.
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48
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Kavaler J, Fu W, Duan H, Noll M, Posakony JW. An essential role for the Drosophila Pax2 homolog in the differentiation of adult sensory organs. Development 1999; 126:2261-72. [PMID: 10207150 DOI: 10.1242/dev.126.10.2261] [Citation(s) in RCA: 64] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The adult peripheral nervous system of Drosophila includes a complex array of mechanosensory organs (bristles) that cover much of the body surface of the fly. The four cells (shaft, socket, sheath, and neuron) which compose each of these organs adopt distinct fates as a result of cell-cell signaling via the Notch (N) pathway. However, the specific mechanisms by which these cells execute their conferred fates are not well understood. Here we show that D-Pax2, the Drosophila homolog of the vertebrate Pax2 gene, has an essential role in the differentiation of the shaft cell. In flies bearing strong loss-of-function mutations in the shaven function of D-Pax2, shaft structures specifically fail to develop. Consistent with this, we find that D-Pax2 protein is expressed in all cells of the bristle lineage during the mitotic (cell fate specification) phase of bristle development, but becomes sharply restricted to the shaft and sheath cells in the post-mitotic (differentiative) phase. Two lines of evidence described here indicate that D-Pax2 expression and function is at least in part downstream of cell fate specification mechanisms such as N signaling. First, we find that the lack of late D-Pax2 expression in the socket cell (the sister of the shaft cell) is controlled by N pathway activity; second, we find that loss of D-Pax2 function is epistatic to the socket-to-shaft cell fate transformation caused by reduced N signaling. Finally, we show that misexpression of D-Pax2 is sufficient to induce the production of ectopic shaft structures. From these results, we propose that D-Pax2 is a high-level transcriptional regulator of the shaft cell differentiation program, and acts downstream of the N signaling pathway as a specific link between cell fate determination and cell differentiation in the bristle lineage.
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Affiliation(s)
- J Kavaler
- Department of Biology, University of California San Diego, La Jolla, CA 92093-0349, USA
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Brunner E, Brunner D, Fu W, Hafen E, Basler K. The dominant mutation Glazed is a gain-of-function allele of wingless that, similar to loss of APC, interferes with normal eye development. Dev Biol 1999; 206:178-88. [PMID: 9986731 DOI: 10.1006/dbio.1998.9136] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Dominant mutations have served as invaluable tools for Drosophila geneticists. Here we analyze the dominant eye mutation Glazed (Gla) that was described by T. H. Morgan more than 50 years ago. We show that Gla causes the loss of photoreceptor cells during pupal stages, in a process reminiscent of apoptosis, with a concomitant overproduction of eye pigment. This phenotype is very similar to that caused by the loss of D-APC, a negative regulator of Wingless (Wg) signal transduction. Genetic analyses reveal however that the Gla gain-of-function phenotype can be reverted to wild-type. By generating a P-element-induced revertant of Gla we demonstrate that Gla is allelic to wg. The molecular lesion in Gla indicates that the insertion of a roo retrotransposon leads to ectopic expression of wg during pupal stages. We show that the Gla phenotype is similar to that caused by ectopic expression of Wg driven by the sevenless (sev) enhancer. In both cases Wg exerts its effect, at least in part, by negatively regulating the expression of the Pax2 homolog sparkling (spa). Gla represents not only the first dominant allele of wg, but it may also be the first allele ever described for wg.
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Affiliation(s)
- E Brunner
- Zoologisches Institut, Universität Zürich, Zürich, 8057, Switzerland
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