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Park JE, Lee J, Ok S, Byun S, Chang EJ, Yoon SE, Kim YJ, Kang MJ. Wg/Wnt1 and Erasp link ER stress to proapoptotic signaling in an autosomal dominant retinitis pigmentosa model. Exp Mol Med 2023:10.1038/s12276-023-01044-7. [PMID: 37464094 PMCID: PMC10394004 DOI: 10.1038/s12276-023-01044-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2023] [Revised: 04/11/2023] [Accepted: 04/17/2023] [Indexed: 07/20/2023] Open
Abstract
The endoplasmic reticulum (ER) is a subcellular organelle essential for cellular homeostasis. Perturbation of ER functions due to various conditions can induce apoptosis. Chronic ER stress has been implicated in a wide range of diseases, including autosomal dominant retinitis pigmentosa (ADRP), which is characterized by age-dependent retinal degeneration caused by mutant rhodopsin alleles. However, the signaling pathways that mediate apoptosis in response to ER stress remain poorly understood. In this study, we performed an unbiased in vivo RNAi screen with a Drosophila ADRP model and found that Wg/Wnt1 mediated apoptosis. Subsequent transcriptome analysis revealed that ER stress-associated serine protease (Erasp), which has been predicted to show serine-type endopeptidase activity, was a downstream target of Wg/Wnt1 during ER stress. Furthermore, knocking down Erasp via RNAi suppressed apoptosis induced by mutant rhodopsin-1 (Rh-1P37H) toxicity, alleviating retinal degeneration in the Drosophila ADRP model. In contrast, overexpression of Erasp resulted in enhanced caspase activity in Drosophila S2 cells treated with apoptotic inducers and the stabilization of the initiator caspase Dronc (Death regulator Nedd2-like caspase) by stimulating DIAP1 (Drosophila inhibitor of apoptosis protein 1) degradation. These findings helped identify a novel cell death signaling pathway involved in retinal degeneration in an autosomal dominant retinitis pigmentosa model.
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Affiliation(s)
- Jung-Eun Park
- Department of Pharmacology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, 05505, Republic of Korea
| | - Jiyoun Lee
- School of Biopharmaceutical and Medical Sciences, Sungshin University, Seoul, 01133, Republic of Korea
| | - Soonhyuck Ok
- Department of Pharmacology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, 05505, Republic of Korea
| | - Seunghee Byun
- Department of Pharmacology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, 05505, Republic of Korea
| | - Eun-Ju Chang
- Department of Biochemistry and Molecular Biology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, 05505, Republic of Korea
- Biomedical Research Center, Asan Institute for Life Sciences, Asan Medical Center, 88, Olympic-ro 43-gil, Songpa-gu, Seoul, 05505, Republic of Korea
| | - Sung-Eun Yoon
- Korea Drosophila Resource Center, Gwangju Institute of Science and Technology (GIST), 123 Cheomdangwagi-ro, Buk-gu, Gwangju, 61005, Republic of Korea
| | - Young-Joon Kim
- School of Life Sciences, Gwangju Institute of Science and Technology (GIST), 123 Cheomdangwagi-ro, Buk-gu, Gwangju, 61005, Republic of Korea
| | - Min-Ji Kang
- Department of Pharmacology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, 05505, Republic of Korea.
- Biomedical Research Center, Asan Institute for Life Sciences, Asan Medical Center, 88, Olympic-ro 43-gil, Songpa-gu, Seoul, 05505, Republic of Korea.
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2
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Hashemi L, Ormsbee ME, Patel PJ, Nielson JA, Ahlander J, Padash Barmchi M. A Drosophila model of HPV16-induced cancer reveals conserved disease mechanism. PLoS One 2022; 17:e0278058. [PMID: 36508448 PMCID: PMC9744332 DOI: 10.1371/journal.pone.0278058] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2022] [Accepted: 11/09/2022] [Indexed: 12/14/2022] Open
Abstract
High-risk human papillomaviruses (HR-HPVs) cause almost all cervical cancers and a significant number of vaginal, vulvar, penile, anal, and oropharyngeal cancers. HPV16 and 18 are the most prevalent types among HR-HPVs and together cause more than 70% of all cervical cancers. Low vaccination rate and lack of molecularly-targeted therapeutics for primary therapy have led to a slow reduction in cervical cancer incidence and high mortality rate. Hence, creating new models of HPV-induced cancer that can facilitate understanding of the disease mechanism and identification of key cellular targets of HPV oncogenes are important for development of new interventions. Here in this study, we used the tissue-specific expression technique, Gal4-UAS, to establish the first Drosophila model of HPV16-induced cancer. Using this technique, we expressed HPV16 oncogenes E5, E6, E7 and the human E3 ligase (hUBE3A) specifically in the epithelia of Drosophila eye, which allows simple phenotype scoring without affecting the viability of the organism. We found that, as in human cells, hUBE3A is essential for cellular abnormalities caused by HPV16 oncogenes in flies. Several proteins targeted for degradation by HPV16 oncoproteins in human cells were also reduced in the Drosophila epithelial cells. Cell polarity and adhesion were compromised, resulting in impaired epithelial integrity. Cells did not differentiate to the specific cell types of ommatidia, but instead were transformed into neuron-like cells. These cells extended axon-like structures to connect to each other and exhibited malignant behavior, migrating away to distant sites. Our findings suggest that given the high conservation of genes and signaling pathways between humans and flies, the Drosophila model of HPV16- induced cancer could serve as an excellent model for understanding the disease mechanism and discovery of novel molecularly-targeted therapeutics.
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Affiliation(s)
- Lydia Hashemi
- Department of Biology, University of Oklahoma, Norman, OK, United States of America
| | - McKenzi E. Ormsbee
- Department of Biology, University of Oklahoma, Norman, OK, United States of America
| | - Prashant J. Patel
- Department of Biology, University of Oklahoma, Norman, OK, United States of America
| | - Jacquelyn A. Nielson
- Stead Family Department of Pediatrics, University of Iowa, Iowa City, IA, United States of America
| | - Joseph Ahlander
- Department of Natural Sciences, Northeastern State University, Broken Arrow, OK, United States of America
| | - Mojgan Padash Barmchi
- Department of Biology, University of Oklahoma, Norman, OK, United States of America
- * E-mail:
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3
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Charlton-Perkins MA, Friedrich M, Cook TA. Semper's cells in the insect compound eye: Insights into ocular form and function. Dev Biol 2021; 479:126-138. [PMID: 34343526 PMCID: PMC8410683 DOI: 10.1016/j.ydbio.2021.07.015] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2021] [Revised: 07/26/2021] [Accepted: 07/28/2021] [Indexed: 11/28/2022]
Abstract
The arthropod compound eye represents one of two major eye types in the animal kingdom and has served as an essential experimental paradigm for defining fundamental mechanisms underlying sensory organ formation, function, and maintenance. One of the most distinguishing features of the compound eye is the highly regular array of lens facets that define individual eye (ommatidial) units. These lens facets are produced by a deeply conserved quartet of cuticle-secreting cells, called Semper cells (SCs). Also widely known as cone cells, SCs were originally identified for their secretion of the dioptric system, i.e. the corneal lens and underlying crystalline cones. Additionally, SCs are now known to execute a diversity of patterning and glial functions in compound eye development and maintenance. Here, we present an integrated account of our current knowledge of SC multifunctionality in the Drosophila compound eye, highlighting emerging gene regulatory modules that may drive the diverse roles for these cells. Drawing comparisons with other deeply conserved retinal glia in the vertebrate single lens eye, this discussion speaks to glial cell origins and opens new avenues for understanding sensory system support programs.
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Affiliation(s)
- Mark A Charlton-Perkins
- Department of Paediatrics, Wellcome-MRC Stem Cell Institute, Jeffrey Cheah Biomedical Centre, University of Cambridge, Puddicombe Way, Cambridge, CB2 0AW, United Kingdom
| | - Markus Friedrich
- Department of Biological Sciences, Wayne State University, 5047 Gullen Mall, Detroit, MI, 48202, USA; Department of Ophthalmological, Visual, and Anatomical Sciences, Wayne State University, School of Medicine, 540 East Canfield Avenue, Detroit, MI, 48201, USA
| | - Tiffany A Cook
- Department of Ophthalmological, Visual, and Anatomical Sciences, Wayne State University, School of Medicine, 540 East Canfield Avenue, Detroit, MI, 48201, USA; Center of Molecular Medicine and Genetics, Wayne State University School of Medicine, 540 East Canfield Avenue, Detroit, MI, 48201, USA.
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4
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Mehta AS, Deshpande P, Chimata AV, Tsonis PA, Singh A. Newt regeneration genes regulate Wingless signaling to restore patterning in Drosophila eye. iScience 2021; 24:103166. [PMID: 34746690 PMCID: PMC8551474 DOI: 10.1016/j.isci.2021.103166] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2021] [Revised: 07/02/2021] [Accepted: 09/21/2021] [Indexed: 12/21/2022] Open
Abstract
Newts utilize their unique genes to restore missing parts by strategic regulation of conserved signaling pathways. Lack of genetic tools poses challenges to determine the function of such genes. Therefore, we used the Drosophila eye model to demonstrate the potential of 5 unique newt (Notophthalmus viridescens) gene(s), viropana1-viropana5 (vna1-vna5), which were ectopically expressed in L 2 mutant and GMR-hid, GMR-GAL4 eye. L 2 exhibits the loss of ventral half of early eye and head involution defective (hid) triggers cell-death during later eye development. Surprisingly, newt genes significantly restore missing photoreceptor cells both in L 2 and GMR>hid background by upregulating cell-proliferation and blocking cell-death, regulating evolutionarily conserved Wingless (Wg)/Wnt signaling pathway and exhibit non-cell-autonomous rescues. Further, Wg/Wnt signaling acts downstream of newt genes. Our data highlights that unique newt proteins can regulate conserved pathways to trigger a robust restoration of missing photoreceptor cells in Drosophila eye model with weak restoration capability.
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Affiliation(s)
| | | | | | | | - Amit Singh
- Department of Biology, University of Dayton, Dayton, OH 45469, USA
- Premedical Program, University of Dayton, Dayton, USA
- Center for Tissue Regeneration and Engineering at Dayton (TREND), University of Dayton, Dayton, USA
- The Integrative Science and Engineering Center, University of Dayton, Dayton, OH 45469, USA
- Center for Genomic Advocacy (TCGA), Indiana State University, Terre Haute, IN, USA
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5
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DeAngelis MW, Coolon JD, Johnson RI. Comparative transcriptome analyses of the Drosophila pupal eye. G3-GENES GENOMES GENETICS 2021; 11:5995320. [PMID: 33561221 PMCID: PMC8043229 DOI: 10.1093/g3journal/jkaa003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/18/2020] [Accepted: 10/08/2020] [Indexed: 12/04/2022]
Abstract
Tissue function is dependent on correct cellular organization and behavior. As a result, the identification and study of genes that contribute to tissue morphogenesis is of paramount importance to the fields of cell and developmental biology. Many of the genes required for tissue patterning and organization are highly conserved between phyla. This has led to the emergence of several model organisms and developmental systems that are used to study tissue morphogenesis. One such model is the Drosophila melanogaster pupal eye that has a highly stereotyped arrangement of cells. In addition, the pupal eye is postmitotic that allows for the study of tissue morphogenesis independent from any effects of proliferation. While the changes in cell morphology and organization that occur throughout pupal eye development are well documented, less is known about the corresponding transcriptional changes that choreograph these processes. To identify these transcriptional changes, we dissected wild-type Canton S pupal eyes and performed RNA-sequencing. Our analyses identified differential expression of many loci that are documented regulators of pupal eye morphogenesis and contribute to multiple biological processes including signaling, axon projection, adhesion, and cell survival. We also identified differential expression of genes not previously implicated in pupal eye morphogenesis such as components of the Toll pathway, several non-classical cadherins, and components of the muscle sarcomere, which could suggest these loci function as novel patterning factors.
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Affiliation(s)
- Miles W DeAngelis
- Department of Biology, Wesleyan University, 52 Lawn Avenue, Middletown, CT 06459, USA
| | - Joseph D Coolon
- Department of Biology, Wesleyan University, 52 Lawn Avenue, Middletown, CT 06459, USA
| | - Ruth I Johnson
- Department of Biology, Wesleyan University, 52 Lawn Avenue, Middletown, CT 06459, USA
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6
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Neuronal diversity and convergence in a visual system developmental atlas. Nature 2020; 589:88-95. [PMID: 33149298 PMCID: PMC7790857 DOI: 10.1038/s41586-020-2879-3] [Citation(s) in RCA: 114] [Impact Index Per Article: 28.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2020] [Accepted: 08/27/2020] [Indexed: 01/01/2023]
Abstract
Deciphering how neuronal diversity is established and maintained requires a detailed knowledge of neuronal gene expression throughout development. In contrast to mammalian brains1,2, the large neuronal diversity of the Drosophila optic lobes3 and its connectome4–6 are almost completely characterized. However, a molecular characterization of this diversity, particularly during development, has been lacking. We present novel insights into brain development through a nearly exhaustive description of the transcriptomic diversity of the optic lobes. We acquired the transcriptome of 275,000 single-cells at adult and five pupal stages, and developed a machine learning framework to assign them to almost 200 cell-types at all timepoints. We discovered two large neuronal populations that wrap neuropils during development but die just before adulthood, as well as neuronal subtypes that partition dorsal and ventral visual circuits by differential Wnt signaling throughout development. Moreover, we showed that neurons of the same type but produced days apart synchronize their transcriptomes shortly after being produced. We also resolved during synaptogenesis neuronal subtypes that converge to indistinguishable transcriptomic profiles in adults while greatly differing in morphology and connectivity. Our datasets almost completely account for the known neuronal diversity of the optic lobes and serve as a paradigm to understand brain development across species.
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7
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Raj A, Chimata AV, Singh A. Motif 1 Binding Protein suppresses wingless to promote eye fate in Drosophila. Sci Rep 2020; 10:17221. [PMID: 33057115 PMCID: PMC7560846 DOI: 10.1038/s41598-020-73891-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2020] [Accepted: 08/31/2020] [Indexed: 01/19/2023] Open
Abstract
The phenomenon of RNA polymerase II (Pol II) pausing at transcription start site (TSS) is one of the key rate-limiting steps in regulating genome-wide gene expression. In Drosophila embryo, Pol II pausing is known to regulate the developmental control genes expression, however, the functional implication of Pol II pausing during later developmental time windows remains largely unknown. A highly conserved zinc finger transcription factor, Motif 1 Binding Protein (M1BP), is known to orchestrate promoter-proximal pausing. We found a new role of M1BP in regulating Drosophila eye development. Downregulation of M1BP function suppresses eye fate resulting in a reduced eye or a "no-eye" phenotype. The eye suppression function of M1BP has no domain constraint in the developing eye. Downregulation of M1BP results in more than two-fold induction of wingless (wg) gene expression along with robust induction of Homothorax (Hth), a negative regulator of eye fate. The loss-of-eye phenotype of M1BP downregulation is dependent on Wg upregulation as downregulation of both M1BP and wg, by using wgRNAi, shows a significant rescue of a reduced eye or a "no-eye" phenotype, which is accompanied by normalizing of wg and hth expression levels in the eye imaginal disc. Ectopic induction of Wg is known to trigger developmental cell death. We found that upregulation of wg as a result of downregulation of M1BP also induces apoptotic cell death, which can be significantly restored by blocking caspase-mediated cell death. Our data strongly imply that transcriptional regulation of wg by Pol II pausing factor M1BP may be one of the important regulatory mechanism(s) during Drosophila eye development.
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Affiliation(s)
- Akanksha Raj
- Department of Biology, University of Dayton, Dayton, OH, 45469, USA
| | | | - Amit Singh
- Department of Biology, University of Dayton, Dayton, OH, 45469, USA. .,Premedical Program, University of Dayton, Dayton, OH, USA. .,Center for Tissue Regeneration and Engineering (TREND), University of Dayton, Dayton, OH, USA. .,Integrative Science and Engineering (ISE), University of Dayton, Dayton, OH, USA. .,Center for Genomic Advocacy (TCGA), Indiana State University, Terre Haute, IN, USA.
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8
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DeAngelis MW, McGhie EW, Coolon JD, Johnson RI. Mask, a component of the Hippo pathway, is required for Drosophila eye morphogenesis. Dev Biol 2020; 464:53-70. [PMID: 32464117 DOI: 10.1016/j.ydbio.2020.05.002] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2020] [Revised: 05/12/2020] [Accepted: 05/13/2020] [Indexed: 12/30/2022]
Abstract
Hippo signaling is an important regulator of tissue size, but it also has a lesser-known role in tissue morphogenesis. Here we use the Drosophila pupal eye to explore the role of the Hippo effector Yki and its cofactor Mask in morphogenesis. We found that Mask is required for the correct distribution and accumulation of adherens junctions and appropriate organization of the cytoskeleton. Accordingly, disrupting mask expression led to severe mis-patterning and similar defects were observed when yki was reduced or in response to ectopic wts. Further, the patterning defects generated by reducing mask expression were modified by Hippo pathway activity. RNA-sequencing revealed a requirement for Mask for appropriate expression of numerous genes during eye morphogenesis. These included genes implicated in cell adhesion and cytoskeletal organization, a comprehensive set of genes that promote cell survival, and numerous signal transduction genes. To validate our transcriptome analyses, we then considered two loci that were modified by Mask activity: FER and Vinc, which have established roles in regulating adhesion. Modulating the expression of either locus modified mask mis-patterning and adhesion phenotypes. Further, expression of FER and Vinc was modified by Yki. It is well-established that the Hippo pathway is responsive to changes in cell adhesion and the cytoskeleton, but our data indicate that Hippo signaling also regulates these structures.
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Affiliation(s)
- Miles W DeAngelis
- Wesleyan University Department of Biology, Middletown CT, 06457, USA.
| | - Emily W McGhie
- Wesleyan University Department of Biology, Middletown CT, 06457, USA.
| | - Joseph D Coolon
- Wesleyan University Department of Biology, Middletown CT, 06457, USA.
| | - Ruth I Johnson
- Wesleyan University Department of Biology, Middletown CT, 06457, USA.
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9
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Coelho DS, Moreno E. Emerging links between cell competition and Alzheimer's disease. J Cell Sci 2019; 132:132/13/jcs231258. [PMID: 31263078 DOI: 10.1242/jcs.231258] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Alzheimer's disease (AD) causes a progressive loss of memory and other cognitive functions, which inexorably debilitates patients. There is still no cure for AD and effective treatments to delay or revert AD are urgently needed. On a molecular level, the excessive accumulation of amyloid-β (Aβ) peptides triggers a complex cascade of pathological events underlying neuronal death, whose details are not yet completely understood. Our laboratory recently discovered that cell competition may play a protective role against AD by eliminating less fit neurons from the brain of Aβ-transgenic flies. Loss of Aβ-damaged neurons through fitness comparison with healthy counterparts is beneficial for the organism, delaying cognitive decline and motor disability. In this Review, we introduce the molecular mechanisms of cell competition, including seminal works on the field and latest advances regarding genetic triggers and effectors of cell elimination. We then describe the biological relevance of competition in the nervous system and discuss how competitive interactions between neurons may arise and be exacerbated in the context of AD. Selection of neurons through fitness comparison is a promising, but still emerging, research field that may open new avenues for the treatment of neurological disorders.
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Affiliation(s)
- Dina S Coelho
- Cell Fitness Laboratory, Champalimaud Centre for the Unknown, Av. Brasília., 1400-038 Lisbon, Portugal
| | - Eduardo Moreno
- Cell Fitness Laboratory, Champalimaud Centre for the Unknown, Av. Brasília., 1400-038 Lisbon, Portugal
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10
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DeAngelis MW, Johnson RI. Dissection of the Drosophila Pupal Retina for Immunohistochemistry, Western Analysis, and RNA Isolation. J Vis Exp 2019. [PMID: 30933080 DOI: 10.3791/59299] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
The Drosophila pupal retina provides an excellent model system for the study of morphogenetic processes during development. In this paper, we present a reliable protocol for the dissection of the delicate Drosophila pupal retina. Our surgical approach utilizes readily-available microdissection tools to open pupae and precisely extract eye-brain complexes. These can be fixed, subjected to immunohistochemistry, and retinas then mounted onto microscope slides and imaged if the goal is to detect cellular or subcellular structures. Alternatively, unfixed retinas can be isolated from brain tissue, lysed in appropriate buffers and utilized for protein gel electrophoresis or mRNA extraction (to assess protein or gene expression, respectively). Significant practice and patience may be required to master the microdissection protocol described, but once mastered, the protocol enables relatively quick isolation of mainly undamaged retinas.
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11
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Sarkar A, Gogia N, Glenn N, Singh A, Jones G, Powers N, Srivastava A, Kango-Singh M, Singh A. A soy protein Lunasin can ameliorate amyloid-beta 42 mediated neurodegeneration in Drosophila eye. Sci Rep 2018; 8:13545. [PMID: 30202077 PMCID: PMC6131139 DOI: 10.1038/s41598-018-31787-7] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2017] [Accepted: 08/24/2018] [Indexed: 01/30/2023] Open
Abstract
Alzheimer's disease (AD), a fatal progressive neurodegenerative disorder, also results from accumulation of amyloid-beta 42 (Aβ42) plaques. These Aβ42 plaques trigger oxidative stress, abnormal signaling, which results in neuronal death by unknown mechanism(s). We misexpress high levels of human Aβ42 in the differentiating retinal neurons of the Drosophila eye, which results in the Alzheimer's like neuropathology. Using our transgenic model, we tested a soy-derived protein Lunasin (Lun) for a possible role in rescuing neurodegeneration in retinal neurons. Lunasin is known to have anti-cancer effect and reduces stress and inflammation. We show that misexpression of Lunasin by transgenic approach can rescue Aβ42 mediated neurodegeneration by blocking cell death in retinal neurons, and results in restoration of axonal targeting from retina to brain. Misexpression of Lunasin downregulates the highly conserved cJun-N-terminal Kinase (JNK) signaling pathway. Activation of JNK signaling can prevent neuroprotective role of Lunasin in Aβ42 mediated neurodegeneration. This neuroprotective function of Lunasin is not dependent on retinal determination gene cascade in the Drosophila eye, and is independent of Wingless (Wg) and Decapentaplegic (Dpp) signaling pathways. Furthermore, Lunasin can significantly reduce mortality rate caused by misexpression of human Aβ42 in flies. Our studies identified the novel neuroprotective role of Lunasin peptide, a potential therapeutic agent that can ameliorate Aβ42 mediated neurodegeneration by downregulating JNK signaling.
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Affiliation(s)
- Ankita Sarkar
- Department of Biology, University of Dayton, Dayton, OH, 45469, USA
| | - Neha Gogia
- Department of Biology, University of Dayton, Dayton, OH, 45469, USA
| | - Neil Glenn
- Premedical Program, University of Dayton, Dayton, OH, 45469, USA
| | - Aditi Singh
- Department of Biology, University of Dayton, Dayton, OH, 45469, USA
| | - Gillian Jones
- Department of Biology and Biotechnology Center, Western Kentucky University, 1906 College Heights Boulevard, TCCW 351, Bowling Green, KY, 42101, USA
| | - Nathan Powers
- Department of Biology and Biotechnology Center, Western Kentucky University, 1906 College Heights Boulevard, TCCW 351, Bowling Green, KY, 42101, USA
| | - Ajay Srivastava
- Department of Biology and Biotechnology Center, Western Kentucky University, 1906 College Heights Boulevard, TCCW 351, Bowling Green, KY, 42101, USA
| | - Madhuri Kango-Singh
- Department of Biology, University of Dayton, Dayton, OH, 45469, USA
- Premedical Program, University of Dayton, Dayton, OH, 45469, USA
- Center for Tissue Regeneration and Engineering at Dayton (TREND), University of Dayton, Dayton, OH, 45469, USA
- The Integrative Science and Engineering Center, University of Dayton, Dayton, OH, 45469, USA
| | - Amit Singh
- Department of Biology, University of Dayton, Dayton, OH, 45469, USA.
- Premedical Program, University of Dayton, Dayton, OH, 45469, USA.
- Center for Tissue Regeneration and Engineering at Dayton (TREND), University of Dayton, Dayton, OH, 45469, USA.
- The Integrative Science and Engineering Center, University of Dayton, Dayton, OH, 45469, USA.
- Center for Genomic Advocacy (TCGA), Indiana State University, Terre Haute, IN, USA.
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12
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Cullin-4 regulates Wingless and JNK signaling-mediated cell death in the Drosophila eye. Cell Death Dis 2016; 7:e2566. [PMID: 28032862 PMCID: PMC5261020 DOI: 10.1038/cddis.2016.338] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2016] [Revised: 09/08/2016] [Accepted: 09/09/2016] [Indexed: 12/28/2022]
Abstract
In all multicellular organisms, the fundamental processes of cell proliferation and cell death are crucial for growth regulation during organogenesis. Strict regulation of cell death is important to maintain tissue homeostasis by affecting processes like regulation of cell number, and elimination of unwanted/unfit cells. The developing Drosophila eye is a versatile model to study patterning and growth, where complex signaling pathways regulate growth and cell survival. However, the molecular mechanisms underlying regulation of these processes is not fully understood. In a gain-of-function screen, we found that misexpression of cullin-4 (cul-4), an ubiquitin ligase, can rescue reduced eye mutant phenotypes. Previously, cul-4 has been shown to regulate chromatin remodeling, cell cycle and cell division. Genetic characterization of cul-4 in the developing eye revealed that loss-of-function of cul-4 exhibits a reduced eye phenotype. Analysis of twin-spots showed that in comparison with their wild-type counterparts, the cul-4 loss-of-function clones fail to survive. Here we show that cul-4 clones are eliminated by induction of cell death due to activation of caspases. Aberrant activation of signaling pathways is known to trigger cell death in the developing eye. We found that Wingless (Wg) and c-Jun-amino-terminal-(NH2)-Kinase (JNK) signaling are ectopically induced in cul-4 mutant clones, and these signals co-localize with the dying cells. Modulating levels of Wg and JNK signaling by using agonists and antagonists of these pathways demonstrated that activation of Wg and JNK signaling enhances cul-4 mutant phenotype, whereas downregulation of Wg and JNK signaling rescues the cul-4 mutant phenotypes of reduced eye. Here we present evidences to demonstrate that cul-4 is involved in restricting Wg signaling and downregulation of JNK signaling-mediated cell death during early eye development. Overall, our studies provide insights into a novel role of cul-4 in promoting cell survival in the developing Drosophila eye.
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13
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Merino MM, Levayer R, Moreno E. Survival of the Fittest: Essential Roles of Cell Competition in Development, Aging, and Cancer. Trends Cell Biol 2016; 26:776-788. [DOI: 10.1016/j.tcb.2016.05.009] [Citation(s) in RCA: 100] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2016] [Revised: 05/20/2016] [Accepted: 05/24/2016] [Indexed: 10/21/2022]
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14
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Two temporal functions of Glass: Ommatidium patterning and photoreceptor differentiation. Dev Biol 2016; 414:4-20. [PMID: 27105580 DOI: 10.1016/j.ydbio.2016.04.012] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2015] [Revised: 04/04/2016] [Accepted: 04/13/2016] [Indexed: 12/28/2022]
Abstract
Much progress has been made in elucidating the molecular networks required for specifying retinal cells, including photoreceptors, but the downstream mechanisms that maintain identity and regulate differentiation remain poorly understood. Here, we report that the transcription factor Glass has a dual role in establishing a functional Drosophila eye. Utilizing conditional rescue approaches, we confirm that persistent defects in ommatidium patterning combined with cell death correlate with the overall disruption of eye morphology in glass mutants. In addition, we reveal that Glass exhibits a separable role in regulating photoreceptor differentiation. In particular, we demonstrate the apparent loss of glass mutant photoreceptors is not only due to cell death but also a failure of the surviving photoreceptors to complete differentiation. Moreover, the late reintroduction of Glass in these developmentally stalled photoreceptors is capable of restoring differentiation in the absence of correct ommatidium patterning. Mechanistically, transcription profiling at the time of differentiation reveals that Glass is necessary for the expression of many genes implicated in differentiation, i.e. rhabdomere morphogenesis, phototransduction, and synaptogenesis. Specifically, we show Glass directly regulates the expression of Pph13, which encodes a transcription factor necessary for opsin expression and rhabdomere morphogenesis. Finally, we demonstrate the ability of Glass to choreograph photoreceptor differentiation is conserved between Drosophila and Tribolium, two holometabolous insects. Altogether, our work identifies a fundamental regulatory mechanism to generate the full complement of cells required for a functional rhabdomeric visual system and provides a critical framework to investigate the basis of differentiation and maintenance of photoreceptor identity.
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15
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Donmez HG, Demirezen S, Beksac MS. The relationship between beta-catenin and apoptosis: A cytological and immunocytochemical examination. Tissue Cell 2016; 48:160-7. [PMID: 27105607 DOI: 10.1016/j.tice.2016.04.001] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2016] [Revised: 03/31/2016] [Accepted: 04/04/2016] [Indexed: 11/17/2022]
Abstract
Disruption of the adhesive role of beta-catenin by caspases has been reported; however, the relationship between the Wnt/beta-catenin signaling pathway and apoptosis remains unclear. Therefore, we aimed to evaluate squamous epithelial cells in cervicovaginal smears by using cytological and immunocytochemical methods to observe changes in the presence and localization of beta-catenin during apoptosis, death receptor-, and mitochondria-mediated apoptosis. We investigated 224 cervicovaginal smears using the Papanicolaou method. Anti-beta-catenin and anti-cleaved caspase 3, 8, and 9 antibodies were used for immunocytochemical staining. Apoptotic cells were negative for beta-catenin. This showed that the Wnt/beta-catenin signaling pathway was inactive in apoptotic cells. However, beta-catenin showed intense positivity in the membrane, cytoplasm, and nucleus of non-apoptotic epithelial cells around these apoptotic cells. Therefore, the Wnt/beta-catenin signaling pathway was active in non-apoptotic epithelial cells, and this activity in non-apoptotic cells may have been induced by apoptotic cells. A highly significant association between the presence of death receptor-mediated apoptosis and the activity of the Wnt/beta-catenin signaling pathway was also found (P<0.001). In conclusion, the Wnt/beta-catenin signaling pathway was found to be inactive in apoptotic cells, but apoptotic cells may induce the Wnt/beta-catenin signaling pathway in non-apoptotic cells to compensate for a decrease in epithelial cells because of apoptosis in order to maintain epithelial tissue integrity.
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Affiliation(s)
- Hanife Guler Donmez
- Department of Biology, Faculty of Science, Hacettepe University, 06800 Beytepe, Ankara, Turkey
| | - Sayeste Demirezen
- Department of Biology, Faculty of Science, Hacettepe University, 06800 Beytepe, Ankara, Turkey.
| | - Mehmet Sinan Beksac
- Department of Gynecology and Obstetrics, Faculty of Medicine, Hacettepe University, 06100 Sıhhiye, Ankara, Turkey
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16
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Abstract
The Wnt/β-catenin signaling is an evolutionarily conserved pathway that regulates a wide range of physiological functions, including embryogenesis, organ maintenance, cell proliferation and cell fate decision. Dysregulation of Wnt/β-catenin signaling has been implicated in various cancers, but its role in cell death has not yet been fully elucidated. Here we show that activation of Wg signaling induces cell death in Drosophila eyes and wings, which depends on dFoxO, a transcription factor known to be involved in cell death. In addition, dFoxO is required for ectopic and endogenous Wg signaling to regulate wing patterning. Moreover, dFoxO is necessary for activated Wg signaling-induced target genes expression. Furthermore, Arm is reciprocally required for dFoxO-induced cell death. Finally, dFoxO physically interacts with Arm both in vitro and in vivo. Thus, we have characterized a previously unknown role of dFoxO in promoting Wg signaling, and that a dFoxO-Arm complex is likely involved in their mutual functions, e.g. cell death.
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17
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Tousled-like kinase mediated a new type of cell death pathway in Drosophila. Cell Death Differ 2015; 23:146-57. [PMID: 26088162 DOI: 10.1038/cdd.2015.77] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2014] [Revised: 04/21/2015] [Accepted: 05/05/2015] [Indexed: 01/09/2023] Open
Abstract
Programmed cell death (PCD) has an important role in sculpting organisms during development. However, much remains to be learned about the molecular mechanism of PCD. We found that ectopic expression of tousled-like kinase (tlk) in Drosophila initiated a new type of cell death. Furthermore, the TLK-induced cell death is likely to be independent of the canonical caspase pathway and other known caspase-independent pathways. Genetically, atg2 RNAi could rescue the TLK-induced cell death, and this function of atg2 was likely distinct from its role in autophagy. In the developing retina, loss of tlk resulted in reduced PCD in the interommatidial cells (IOCs). Similarly, an increased number of IOCs was present in the atg2 deletion mutant clones. However, double knockdown of tlk and atg2 by RNAi did not have a synergistic effect. These results suggested that ATG2 may function downstream of TLK. In addition to a role in development, tlk and atg2 RNAi could rescue calcium overload-induced cell death. Together, our results suggest that TLK mediates a new type of cell death pathway that occurs in both development and calcium cytotoxicity.
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Zhang S, Chen C, Wu C, Yang Y, Li W, Xue L. The canonical Wg signaling modulates Bsk-mediated cell death in Drosophila. Cell Death Dis 2015; 6:e1713. [PMID: 25855961 PMCID: PMC4650552 DOI: 10.1038/cddis.2015.85] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2014] [Revised: 02/24/2015] [Accepted: 02/24/2015] [Indexed: 12/21/2022]
Abstract
Cell death is an essential regulatory mechanism for removing unneeded cells in animal development and tissue homeostasis. The c-Jun N-terminal kinase (JNK) pathway has pivotal roles in the regulation of cell death in response to various intrinsic and extrinsic stress signals. The canonical Wingless (Wg) signaling has been implicated in cell proliferation and cell fate decisions, whereas its role in cell death remains largely elusive. Here, we report that activated Bsk (the Drosophila JNK homolog) induced cell death is mediated by the canonical Wg signaling. First, loss of Wg signaling abrogates Bsk-mediated caspase-independent cell death. Second, activation of Wg signaling promotes cell death in a caspase-independent manner. Third, activation of Bsk signaling results in upregulated transcription of wingless (wg) gene. Finally, Wg pathway participates in the physiological function of Bsk signaling in development. These findings not only reveal a previously undiscovered role of Wg signaling in Bsk-mediated cell death, but also provide a novel mechanism for the interplay between the two important signaling pathways in development.
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Affiliation(s)
- S Zhang
- Institute of Intervention Vessel, Shanghai 10th People's Hospital, Shanghai Key Laboratory of Signaling and Disease Research, School of Life Science and Technology, Tongji University, 1239 Siping Road, Shanghai 200092, PR China
| | - C Chen
- Institute of Intervention Vessel, Shanghai 10th People's Hospital, Shanghai Key Laboratory of Signaling and Disease Research, School of Life Science and Technology, Tongji University, 1239 Siping Road, Shanghai 200092, PR China
| | - C Wu
- Institute of Intervention Vessel, Shanghai 10th People's Hospital, Shanghai Key Laboratory of Signaling and Disease Research, School of Life Science and Technology, Tongji University, 1239 Siping Road, Shanghai 200092, PR China
| | - Y Yang
- Institute of Intervention Vessel, Shanghai 10th People's Hospital, Shanghai Key Laboratory of Signaling and Disease Research, School of Life Science and Technology, Tongji University, 1239 Siping Road, Shanghai 200092, PR China
| | - W Li
- Institute of Intervention Vessel, Shanghai 10th People's Hospital, Shanghai Key Laboratory of Signaling and Disease Research, School of Life Science and Technology, Tongji University, 1239 Siping Road, Shanghai 200092, PR China
| | - L Xue
- Institute of Intervention Vessel, Shanghai 10th People's Hospital, Shanghai Key Laboratory of Signaling and Disease Research, School of Life Science and Technology, Tongji University, 1239 Siping Road, Shanghai 200092, PR China
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19
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Cell death in development: Signaling pathways and core mechanisms. Semin Cell Dev Biol 2015; 39:12-9. [PMID: 25668151 DOI: 10.1016/j.semcdb.2015.02.001] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2014] [Revised: 01/22/2015] [Accepted: 02/02/2015] [Indexed: 11/20/2022]
Abstract
Programmed cell death eliminates unneeded and dangerous cells in a timely and effective manner during development. In this review, we examine the role cell death plays during development in worms, flies and mammals. We discuss signaling pathways that regulate developmental cell death, and describe how they communicate with the core cell death pathways. In most organisms, the majority of developmental cell death is seen in the nervous system. Therefore we focus on what is known about the regulation of developmental cell death in this tissue. Understanding how the cell death is regulated during development may provide insight into how this process can be manipulated in the treatment of disease.
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21
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Merino M, Rhiner C, Portela M, Moreno E. “Fitness Fingerprints” Mediate Physiological Culling of Unwanted Neurons in Drosophila. Curr Biol 2013; 23:1300-9. [DOI: 10.1016/j.cub.2013.05.053] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2013] [Revised: 05/01/2013] [Accepted: 05/28/2013] [Indexed: 11/28/2022]
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22
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Weasner BM, Kumar JP. Competition among gene regulatory networks imposes order within the eye-antennal disc of Drosophila. Development 2013; 140:205-15. [PMID: 23222441 DOI: 10.1242/dev.085423] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The eye-antennal disc of Drosophila gives rise to numerous adult tissues, including the compound eyes, ocelli, antennae, maxillary palps and surrounding head capsule. The fate of each tissue is governed by the activity of unique gene regulatory networks (GRNs). The fate of the eye, for example, is controlled by a set of fourteen interlocking genes called the retinal determination (RD) network. Mutations within network members lead to replacement of the eyes with head capsule. Several studies have suggested that in these instances all retinal progenitor and precursor cells are eliminated via apoptosis and as a result the surrounding head capsule proliferates to compensate for retinal tissue loss. This model implies that the sole responsibility of the RD network is to promote the fate of the eye. We have re-analyzed eyes absent mutant discs and propose an alternative model. Our data suggests that in addition to promoting an eye fate the RD network simultaneously functions to actively repress GRNs that are responsible for directing antennal and head capsule fates. Compromising the RD network leads to the inappropriate expression of several head capsule selector genes such as cut, Lim1 and wingless. Instead of undergoing apoptosis, a population of mutant retinal progenitors and precursor cells adopt a head capsule fate. This transformation is accompanied by an adjustment of cell proliferation rates such that just enough head capsule is generated to produce an intact adult head. We propose that GRNs simultaneously promote primary fates, inhibit alternative fates and establish cell proliferation states.
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Affiliation(s)
- Bonnie M Weasner
- Department of Biology, Indiana University, Bloomington, IN 47405, USA
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23
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Katanaev VL, Kryuchkov MV. The eye of Drosophila as a model system for studying intracellular signaling in ontogenesis and pathogenesis. BIOCHEMISTRY (MOSCOW) 2012; 76:1556-81. [DOI: 10.1134/s0006297911130116] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
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24
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Archbold HC, Yang YX, Chen L, Cadigan KM. How do they do Wnt they do?: regulation of transcription by the Wnt/β-catenin pathway. Acta Physiol (Oxf) 2012; 204:74-109. [PMID: 21624092 DOI: 10.1111/j.1748-1716.2011.02293.x] [Citation(s) in RCA: 101] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
Wnt/β-catenin signalling is known to play many roles in metazoan development and tissue homeostasis. Misregulation of the pathway has also been linked to many human diseases. In this review, specific aspects of the pathway's involvement in these processes are discussed, with an emphasis on how Wnt/β-catenin signalling regulates gene expression in a cell and temporally specific manner. The T-cell factor (TCF) family of transcription factors, which mediate a large portion of Wnt/β-catenin signalling, will be discussed in detail. Invertebrates contain a single TCF gene that contains two DNA-binding domains, the high mobility group (HMG) domain and the C-clamp, which increases the specificity of DNA binding. In vertebrates, the situation is more complex, with four TCF genes producing many isoforms that contain the HMG domain, but only some of which possess a C-clamp. Vertebrate TCFs have been reported to act in concert with many other transcription factors, which may explain how they obtain sufficient specificity for specific DNA sequences, as well as how they achieve a wide diversity of transcriptional outputs in different cells.
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Affiliation(s)
- H C Archbold
- Program in Cell and Molecular Biology, University of Michigan, Ann Arbor, 48109-1048, USA
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25
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Xin N, Benchabane H, Tian A, Nguyen K, Klofas L, Ahmed Y. Erect Wing facilitates context-dependent Wnt/Wingless signaling by recruiting the cell-specific Armadillo-TCF adaptor Earthbound to chromatin. Development 2011; 138:4955-67. [PMID: 22028028 DOI: 10.1242/dev.068890] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
During metazoan development, the Wnt/Wingless signal transduction pathway is activated repetitively to direct cell proliferation, fate specification, differentiation and apoptosis. Distinct outcomes are elicited by Wnt stimulation in different cellular contexts; however, mechanisms that confer context specificity to Wnt signaling responses remain largely unknown. Starting with an unbiased forward genetic screen in Drosophila, we recently uncovered a novel mechanism by which the cell-specific co-factor Earthbound 1 (Ebd1), and its human homolog jerky, promote interaction between the Wnt pathway transcriptional co-activators β-catenin/Armadillo and TCF to facilitate context-dependent Wnt signaling responses. Here, through the same genetic screen, we find an unanticipated requirement for Erect Wing (Ewg), the fly homolog of the human sequence-specific DNA-binding transcriptional activator nuclear respiratory factor 1 (NRF1), in promoting contextual regulation of Wingless signaling. Ewg and Ebd1 functionally interact with the Armadillo-TCF complex and mediate the same context-dependent Wingless signaling responses. In addition, Ewg and Ebd1 have similar cell-specific expression profiles, bind to each other directly and also associate with chromatin at shared genomic sites. Furthermore, recruitment of Ebd1 to chromatin is abolished in the absence of Ewg. Our findings provide in vivo evidence that recruitment of a cell-specific co-factor complex to specific chromatin sites, coupled with its ability to facilitate Armadillo-TCF interaction and transcriptional activity, promotes contextual regulation of Wnt/Wingless signaling responses.
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Affiliation(s)
- Nan Xin
- Department of Genetics and Norris Cotton Cancer Center, Dartmouth Medical School, Hanover, NH 03755, USA
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26
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Overlapping functions of microRNAs in control of apoptosis during Drosophila embryogenesis. Cell Death Differ 2011; 19:839-46. [PMID: 22095284 PMCID: PMC3321623 DOI: 10.1038/cdd.2011.161] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Regulation of apoptosis is crucial for tissue homeostasis under normal development and environmental stress. In Drosophila, cell death occurs in different developmental processes including embryogenesis. Here, we report that two members of the miR-2 seed family of microRNAs, miR-6 and miR-11, function together to limit the level of apoptosis during Drosophila embryonic development. Mutants lacking both miR-6 and miR-11 show embryonic lethality and defects in the central nervous system (CNS). We provide evidence that miR-6/11 functions through regulation of the proapoptotic genes, reaper (rpr), head involution defective (hid), grim and sickle (skl). Upregulation of these proapoptotic genes is responsible for the elevated apoptosis and the CNS defects in the mutants. These findings demonstrate that the activity of the proapoptotic genes is kept in check by miR-6/11 to ensure normal development.
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27
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Yan, an ETS-domain transcription factor, negatively modulates the Wingless pathway in the Drosophila eye. EMBO Rep 2011; 12:1047-54. [PMID: 21869817 DOI: 10.1038/embor.2011.159] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2011] [Revised: 07/07/2011] [Accepted: 07/08/2011] [Indexed: 01/23/2023] Open
Abstract
We report the identification of yan, an ETS-domain transcription factor belonging to the Drosophila epidermal growth factor receptor (DER) pathway, as an antagonist of the Wingless signalling pathway. We demonstrate that cells lacking yan function in the Drosophila eye show increased Wingless pathway activity, and inhibition of Wingless signalling in yan(-/-) cells rescues the yan mutant phenotype. Biochemical analysis shows that Yan physically associates with Armadillo, a crucial effector of the Wingless pathway, thereby suggesting a direct regulatory mechanism. We conclude that yan represents a new and unsuspected molecular link between the Wingless and DER pathways.
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28
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Yanfeng WA, Berhane H, Mola M, Singh J, Jenny A, Mlodzik M. Functional dissection of phosphorylation of Disheveled in Drosophila. Dev Biol 2011; 360:132-42. [PMID: 21963539 DOI: 10.1016/j.ydbio.2011.09.017] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2010] [Revised: 08/23/2011] [Accepted: 09/14/2011] [Indexed: 01/25/2023]
Abstract
Disheveled/Dsh proteins (Dvl in mammals) are core components of both Wnt/Wg-signaling pathways: canonical β-catenin signaling and Frizzled (Fz)-planar cell polarity (PCP) signaling. Although Dsh is a key cytoplasmic component of both Wnt/Fz-pathways, regulation of its signaling specificity is not well understood. Dsh is phosphorylated, but the functional significance of its phosphorylation remains unclear. We have systematically investigated the phosphorylation of Dsh by combining mass-spectrometry analyses, biochemical studies, and in vivo genetic methods in Drosophila. Our approaches identified multiple phospho-residues of Dsh in vivo. Our data define three novel and unexpected conclusions: (1) strikingly and in contrast to common assumptions, all conserved serines/threonines are non-essential for Dsh function in either pathway; (2) phosphorylation of conserved Tyrosine473 in the DEP domain is critical for PCP-signaling - Dsh(Y473F) behaves like a PCP-specific allele; and (3) defects associated with the PCP specific dsh(1) allele, Dsh(K417M), located within a putative Protein Kinase C consensus site, are likely due to a post-translational modification requirement of Lys417, rather than phosphorylation nearby. In summary, our combined data indicate that while many Ser/Thr and Tyr residues are indeed phosphorylated in vivo, strikingly most of these phosphorylation events are not critical for Dsh function with the exception of DshY473.
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Affiliation(s)
- Wang A Yanfeng
- Dept. of Developmental & Regenerative Biology, Mount Sinai School of Medicine, One Gustave L. Levy Place, New York, NY 10029, USA
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29
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Tare M, Modi RM, Nainaparampil JJ, Puli OR, Bedi S, Fernandez-Funez P, Kango-Singh M, Singh A. Activation of JNK signaling mediates amyloid-ß-dependent cell death. PLoS One 2011; 6:e24361. [PMID: 21949710 PMCID: PMC3173392 DOI: 10.1371/journal.pone.0024361] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2011] [Accepted: 08/07/2011] [Indexed: 11/21/2022] Open
Abstract
BACKGROUND Alzheimer's disease (AD) is an age related progressive neurodegenerative disorder. One of the reasons for Alzheimer's neuropathology is the generation of large aggregates of Aß42 that are toxic in nature and induce oxidative stress, aberrant signaling and many other cellular alterations that trigger neuronal cell death. However, the exact mechanisms leading to cell death are not clearly understood. METHODOLOGY/PRINCIPAL FINDINGS We employed a Drosophila eye model of AD to study how Aß42 causes cell death. Misexpression of higher levels of Aß42 in the differentiating photoreceptors of fly retina rapidly induced aberrant cellular phenotypes and cell death. We found that blocking caspase-dependent cell death initially blocked cell death but did not lead to a significant rescue in the adult eye. However, blocking the levels of c-Jun NH(2)-terminal kinase (JNK) signaling pathway significantly rescued the neurodegeneration phenotype of Aß42 misexpression both in eye imaginal disc as well as the adult eye. Misexpression of Aß42 induced transcriptional upregulation of puckered (puc), a downstream target and functional read out of JNK signaling. Moreover, a three-fold increase in phospho-Jun (activated Jun) protein levels was seen in Aß42 retina as compared to the wild-type retina. When we blocked both caspases and JNK signaling simultaneously in the fly retina, the rescue of the neurodegenerative phenotype is comparable to that caused by blocking JNK signaling pathway alone. CONCLUSIONS/SIGNIFICANCE Our data suggests that (i) accumulation of Aß42 plaques induces JNK signaling in neurons and (ii) induction of JNK contributes to Aß42 mediated cell death. Therefore, inappropriate JNK activation may indeed be relevant to the AD neuropathology, thus making JNK a key target for AD therapies.
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Affiliation(s)
- Meghana Tare
- Department of Biology, University of Dayton, Dayton, Ohio, United States of America
| | - Rohan M. Modi
- Premedical Program, University of Dayton, Dayton, Ohio, United States of America
| | | | - Oorvashi Roy Puli
- Department of Biology, University of Dayton, Dayton, Ohio, United States of America
| | - Shimpi Bedi
- Department of Biology, University of Dayton, Dayton, Ohio, United States of America
| | - Pedro Fernandez-Funez
- Departments of Neurology and Neuroscience, McKnight Brain Institute, University of Florida, Gainesville, Florida, United States of America
| | - Madhuri Kango-Singh
- Department of Biology, University of Dayton, Dayton, Ohio, United States of America
- Premedical Program, University of Dayton, Dayton, Ohio, United States of America
- Center for Tissue Regeneration and Engineering at Dayton (TREND), University of Dayton, Dayton, Ohio, United States of America
| | - Amit Singh
- Department of Biology, University of Dayton, Dayton, Ohio, United States of America
- Premedical Program, University of Dayton, Dayton, Ohio, United States of America
- Center for Tissue Regeneration and Engineering at Dayton (TREND), University of Dayton, Dayton, Ohio, United States of America
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30
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Takemura M, Adachi-Yamada T. Cell death and selective adhesion reorganize the dorsoventral boundary for zigzag patterning of Drosophila wing margin hairs. Dev Biol 2011; 357:336-46. [PMID: 21781959 DOI: 10.1016/j.ydbio.2011.07.007] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2011] [Revised: 06/30/2011] [Accepted: 07/05/2011] [Indexed: 11/17/2022]
Abstract
Animal tissues and organs are comprised of several types of cells, which are often arranged in a well-ordered pattern. The posterior part of the Drosophila wing margin is covered with a double row of long hairs, which are equally and alternately derived from the dorsal and ventral sides of the wing, exhibiting a zigzag pattern in the lateral view. How this geometrically regular pattern is formed has not been fully understood. In this study, we show that this zigzag pattern is created by rearrangement of wing margin cells along the dorsoventral boundary flanked by the double row of hair cells during metamorphosis. This cell rearrangement is induced by selective apoptosis of wing margin cells that are spatially separated from hair cells. As a result of apoptosis, the remaining wing margin cells are rearranged in a well-ordered manner, which shapes corrugated lateral sides of both dorsal and ventral edges to interlock them for zigzag patterning. We further show that the corrugated topology of the wing edges is achieved by cell-type specific expression and localization of four kinds of NEPH1/nephrin family proteins through heterophilic adhesion between wing margin cells and hair cells. Homophilic E-cadherin adhesion is also required for attachment of the corrugated dorsoventral edges. Taken together, our results demonstrate that sequential coordination of apoptosis and epithelial architecture with selective adhesion creates the zigzag hair alignment. This may be a common mechanism for geometrically ordered repetitive packing of several types of cells in similarly patterned developmental fields such as the mammalian organ of Corti.
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Affiliation(s)
- Masahiko Takemura
- Department of Biology, Graduate School of Science, Kobe University, 1-1 Rokkodai, Nada-ku, Kobe 657-8501, Japan
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31
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Benchabane H, Xin N, Tian A, Hafler BP, Nguyen K, Ahmed A, Ahmed Y. Jerky/Earthbound facilitates cell-specific Wnt/Wingless signalling by modulating β-catenin-TCF activity. EMBO J 2011; 30:1444-58. [PMID: 21399610 DOI: 10.1038/emboj.2011.67] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2010] [Accepted: 02/10/2011] [Indexed: 12/29/2022] Open
Abstract
Wnt/Wingless signal transduction directs fundamental developmental processes, and upon hyperactivation triggers colorectal adenoma/carcinoma formation. Responses to Wnt stimulation are cell specific and diverse; yet, how cell context modulates Wnt signalling outcome remains obscure. In a Drosophila genetic screen for components that promote Wingless signalling, we identified Earthbound 1 (Ebd1), a novel member in a protein family containing Centromere Binding Protein B (CENPB)-type DNA binding domains. Ebd1 is expressed in only a subset of Wingless responsive cell types, and is required for only a limited number of Wingless-dependent processes. In addition, Ebd1 shares sequence similarity and can be functionally replaced with the human CENPB domain protein Jerky, previously implicated in juvenile myoclonic epilepsy development. Both Jerky and Ebd1 interact directly with the Wnt/Wingless pathway transcriptional co-activators β-catenin/Armadillo and T-cell factor (TCF). In colon carcinoma cells, Jerky facilitates Wnt signalling by promoting association of β-catenin with TCF and recruitment of β-catenin to chromatin. These findings indicate that tissue-restricted transcriptional co-activators facilitate cell-specific Wnt/Wingless signalling responses by modulating β-catenin-TCF activity.
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Affiliation(s)
- Hassina Benchabane
- Department of Genetics and the Norris Cotton Cancer Center, Dartmouth Medical School, Hanover, NH, USA
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32
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Cordero JB, Cagan RL. Canonical wingless signaling regulates cone cell specification in the Drosophila retina. Dev Dyn 2010; 239:875-84. [PMID: 20140910 DOI: 10.1002/dvdy.22235] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Correct tissue patterning during development involves multiple morphogenetic events that include specification of different cell fates, cell proliferation, cell death, and coordinated changes in cell shape, position, and adhesion. Here, we use the Drosophila retina to explore the molecular mechanisms that regulate and integrate these various events. In a previous report, we found that wingless (wg) was required to induce a previously unknown surge of cell death ("early death") in the pupal retina. Here, we show that wg is also required to induce the more widely studied mid-pupal cell death ("late death") in a process that involves regulation of DIAP1. Furthermore, our data suggest that wg has a previously unreported role in specifying the glial-like cone cells. This activity requires canonical Wg signaling and is linked with Notch pathway activity. Our work broadens the role of canonical Wg signaling to encompass multiple patterning steps in the emerging Drosophila retina.
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Affiliation(s)
- Julia B Cordero
- Department of Developmental and Regenerative Biology, Mount Sinai School of Medicine, New York, New York 10029, USA
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Nicholson SC, Gilbert MM, Nicolay BN, Frolov MV, Moberg KH. The archipelago tumor suppressor gene limits rb/e2f-regulated apoptosis in developing Drosophila tissues. Curr Biol 2009; 19:1503-10. [PMID: 19733076 DOI: 10.1016/j.cub.2009.07.068] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2009] [Revised: 07/25/2009] [Accepted: 07/28/2009] [Indexed: 10/20/2022]
Abstract
BACKGROUND The Drosophila archipelago gene (ago) encodes the specificity component of a ubiquitin ligase that targets the cyclin E and dMyc proteins for degradation. Its human ortholog, Fbw7, is commonly lost in cancers, suggesting that failure to degrade ago/Fbw7 targets drives excess tissue growth. RESULTS We find that ago loss induces hyperplasia of some organs but paradoxically reduces the size of the adult eye. This reflects a requirement for ago to restrict apoptotic activity of the rbf1/de2f1 pathway adjacent to the eye-specific morphogenetic furrow (MF): ago mutant cells display elevated de2f1 activity, express the prodeath dE2f1 targets hid and rpr, and undergo high rates of apoptosis. These phenotypes are dependent on rbf1, de2f1, hid, and the rbf1/de2f1 regulators cyclin E and dacapo but are independent of dp53. A transactivation-deficient de2f1 allele blocks MF-associated apoptosis of ago mutant cells but does not retard their clonal overgrowth, indicating that intact de2f1 function is required for the death but not overproliferation of ago cells. Epidermal growth factor receptor (EGFR) and wingless (wg) alleles also modify the ago apoptotic phenotype, indicating that these pathways may modulate the underlying sensitivity of ago mutant cells to apoptotic signals. CONCLUSIONS These data show that ago loss requires a collaborating block in cell death to efficiently drive tissue overgrowth and that this conditional phenotype reflects a role for ago in restricting apoptotic output of the rbf1/de2f1 pathway. Moreover, the susceptibility of ago mutant cells to succumb to this apoptotic program appears to depend on local variations in extracellular signaling that could thus determine tissue-specific fates of ago mutant cells.
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Affiliation(s)
- Sarah C Nicholson
- Department of Cell Biology, Emory University School of Medicine, Atlanta, GA 30322, USA
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Yang X, ZarinKamar N, Bao R, Friedrich M. Probing the Drosophila retinal determination gene network in Tribolium (I): The early retinal genes dachshund, eyes absent and sine oculis. Dev Biol 2009; 333:202-14. [DOI: 10.1016/j.ydbio.2009.02.040] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2008] [Revised: 02/18/2009] [Accepted: 02/19/2009] [Indexed: 12/24/2022]
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Benchabane H, Ahmed Y. The adenomatous polyposis coli tumor suppressor and Wnt signaling in the regulation of apoptosis. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2009; 656:75-84. [PMID: 19928354 DOI: 10.1007/978-1-4419-1145-2_7] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The adenomatous polyposis coli (APC) tumor suppressor is an essential negative regulator in the evolutionarily conserved Wnt/Wingless (Wg) signal transduction pathway. During normal development, Wnt signaling is required not only to induce cell proliferation and cell fate specification, but also to induce apoptotic cell death. However in some malignant states triggered by APC loss, inappropriate activation of Wnt signaling promotes cell survival and inhibits cell death, indicating that the cellular response to APC loss and Wnt signaling is highly dependent on cell context. This chapter summarizes our current understanding of the role of APC and Wnt signaling in the regulation of apoptosis, based upon studies from fly and mouse in vivo models, as well as cultured carcinoma cells.
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Tanaka-Matakatsu M, Xu J, Cheng L, Du W. Regulation of apoptosis of rbf mutant cells during Drosophila development. Dev Biol 2008; 326:347-56. [PMID: 19100727 DOI: 10.1016/j.ydbio.2008.11.035] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2008] [Accepted: 11/19/2008] [Indexed: 12/19/2022]
Abstract
Inactivation of the retinoblastoma gene Rb leads to defects in cell proliferation, differentiation, or apoptosis, depending on specific cell or tissue types. To gain insights into the genes that can modulate the consequences of Rb inactivation, we carried out a genetic screen in Drosophila to identify mutations that affected apoptosis induced by inactivation of the Retinoblastoma-family protein (rbf) and identified a mutation that blocked apoptosis induced by rbf. We found this mutation to be a new allele of head involution defective (hid) and showed that hid expression is deregulated in rbf mutant cells in larval imaginal discs. We identified an enhancer that regulates hid expression in response to developmental cues as well as to radiation and demonstrated that this hid enhancer is directly repressed by RBF through an E2F binding site. These observations indicate that apoptosis of rbf mutant cells is mediated by an upregulation of hid. Finally, we showed that bantam, a miRNA that regulates hid translation, is expressed in the interommatidial cells in the larval eye discs and modulates the survival of rbf mutant cells.
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Affiliation(s)
- Miho Tanaka-Matakatsu
- Ben May Department for Cancer Research, the University of Chicago, Chicago, IL 60637, USA
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Regulation of the feedback antagonist naked cuticle by Wingless signaling. Dev Biol 2008; 321:446-54. [PMID: 18585374 DOI: 10.1016/j.ydbio.2008.05.551] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2008] [Revised: 05/24/2008] [Accepted: 05/27/2008] [Indexed: 11/20/2022]
Abstract
Signaling pathways usually activate transcriptional targets in a cell type-specific manner. Notable exceptions are pathway-specific feedback antagonists, which serve to restrict the range or duration of the signal. These factors are often activated by their respective pathways in a broad array of cell types. For example, the Wnt ligand Wingless (Wg) activates the naked cuticle (nkd) gene in all tissues examined throughout Drosophila development. How does the nkd gene respond in such an unrestricted manner to Wg signaling? Analysis in cell culture revealed regions of the nkd locus that contain Wg response elements (WREs) that are directly activated by the pathway via the transcription factor TCF. In flies, Wg signaling activates these WREs in multiple tissues, in distinct but overlapping patterns. These WREs are necessary and largely sufficient for nkd expression in late stage larval tissues, but only contribute to part of the embryonic expression pattern of nkd. These results demonstrate that nkd responsiveness to Wg signaling is achieved by several WREs which are broadly (but not universally) activated by the pathway. The existence of several WREs in the nkd locus may have been necessary to allow the Wg signaling-Nkd feedback circuit to remain intact as Wg expression diversified during animal evolution.
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Novel TCF-binding sites specify transcriptional repression by Wnt signalling. EMBO J 2008; 27:1436-46. [PMID: 18418383 DOI: 10.1038/emboj.2008.80] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2007] [Accepted: 03/26/2008] [Indexed: 12/22/2022] Open
Abstract
Both transcriptional activation and repression have essential functions in maintaining proper spatial and temporal control of gene expression. Although Wnt signalling is often associated with gene activation, we have identified several directly repressed targets of Wnt signalling in Drosophila. Here, we explore how individual Wnt target genes are specified for signal-induced activation or repression. Similar to activation, repression required binding of Armadillo (Arm) to the N terminus of TCF. However, TCF/Arm mediated repression by binding to DNA motifs that are markedly different from typical TCF-binding sites. Conversion of the novel motifs to standard TCF-binding sites reversed the mode of regulation, resulting in Wnt-mediated activation instead of repression. A mutant form of Arm defective in activation was still functional for repression, indicating that distinct domains of the protein are required for each activity. This study suggests that the sequence of TCF-binding sites allosterically regulates the TCF/Arm complex to effect either transcriptional activation or repression.
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Spenito and Split ends act redundantly to promote Wingless signaling. Dev Biol 2008; 314:100-11. [DOI: 10.1016/j.ydbio.2007.11.023] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2007] [Revised: 11/10/2007] [Accepted: 11/12/2007] [Indexed: 11/21/2022]
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Benchabane H, Hughes EG, Takacs CM, Baird JR, Ahmed Y. Adenomatous polyposis coli is present near the minimal level required for accurate graded responses to the Wingless morphogen. Development 2008; 135:963-71. [PMID: 18234723 DOI: 10.1242/dev.013805] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The mechanisms by which the Wingless (Wg) morphogen modulates the activity of the transcriptional activator Armadillo (Arm) to elicit precise, concentration-dependent cellular responses remain uncertain. Arm is targeted for proteolysis by the Axin/Adenomatous polyposis coli (Apc1 and Apc2)/Zeste-white 3 destruction complex, and Wg-dependent inactivation of destruction complex activity is crucial to trigger Arm signaling. In the prevailing model for Wg transduction, only Axin levels limit destruction complex activity, whereas Apc is present in vast excess. To test this model, we reduced Apc activity to different degrees, and analyzed the effects on three concentration-dependent responses to Arm signaling that specify distinct retinal photoreceptor fates. We find that both Apc1 and Apc2 negatively regulate Arm activity in photoreceptors, but that the relative contribution of Apc1 is much greater than that of Apc2. Unexpectedly, a less than twofold reduction in total Apc activity, achieved by loss of Apc2, decreases the effective threshold at which Wg elicits a cellular response, thereby resulting in ectopic responses that are spatially restricted to regions with low Wg concentration. We conclude that Apc activity is not present in vast excess, but instead is near the minimal level required for accurate graded responses to the Wg morphogen.
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Affiliation(s)
- Hassina Benchabane
- Department of Genetics and the Norris Cotton Cancer Center, Dartmouth Medical School, Hanover, NH 03755, USA
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Yi H, Nakamura REI, Mohamed O, Dufort D, Hackam AS. Characterization of Wnt signaling during photoreceptor degeneration. Invest Ophthalmol Vis Sci 2008; 48:5733-41. [PMID: 18055826 DOI: 10.1167/iovs.07-0097] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
PURPOSE The Wnt pathway is an essential signaling cascade that regulates multiple processes in developing and adult tissues, including differentiation, cellular survival, and stem cell proliferation. The authors recently demonstrated altered expression of Wnt pathway genes during photoreceptor death in rd1 mice, suggesting an involvement for Wnt signaling in the disease process. In this study, the authors investigated the role of Wnt signaling in retinal degeneration. METHODS The Wnt signaling reporter mouse line Tcf-LacZ was crossed with retinal degeneration rd1 mice, and beta-galactosidase expression was used to localize Wnt signaling during photoreceptor death. To analyze the role of Wnt signaling activation, primary mixed retinal cultures were prepared, and XTT and TUNEL assays were used to quantify cell death. Luciferase reporter assays were used to measure Wnt signaling. RESULTS The canonical Wnt signaling pathway was activated in Müller glia and the ganglion cell layer during rod photoreceptor degeneration in rd1/Tcf-LacZ mice. Wnt signaling was confirmed in cultured primary Müller glia. Furthermore, Wnt signaling activators protected photoreceptors in primary retinal cultures from H(2)O(2)-induced oxidative stress. The Wnt ligands Wnt5a, Wnt5b, Wnt10a, and Wnt13 were expressed in the degenerating retina and are candidate Wnt signaling activators in vivo. CONCLUSIONS This study is the first demonstration that Wnt signaling is activated in the degenerating retina and that it protects retinal cultures from oxidative stress. These data suggest that Wnt signaling is a component of the glial protective response during photoreceptor injury. Therefore, inducing Wnt activation, alone or in combination with growth factors, may increase the threshold for apoptosis and halt or delay further photoreceptor degeneration.
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Affiliation(s)
- Hyun Yi
- Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, FL 33136, USA
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42
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Abstract
The secreted morphogen Wingless (Wg) has a variety of functions throughout Drosophila eye development, controlling tissue specification, growth, and patterning. Wg plays a critical role in subdividing the eye imaginal disc into separate primordia that will give rise to the adult retina and the surrounding head capsule. During larval development, wg is expressed in the anterior lateral margins of the eye disc, regions that will give rise to head cuticle; Wg signaling promotes the head fate and prevents these marginal regions from initiating ectopic photoreceptor differentiation. Expression of wg at the dorsal margin is earlier and stronger than at the ventral margin, allowing Wg to contribute to specifying the dorsal domain of the eye disc. Finally, during the pupal stages, wg expression surrounds the entire eye and a concentric gradient of Wg establishes several distinct peripheral retinal cell fates. This chapter reviews these aspects of Wg function and describes how to generate clones of cells mutant for genes encoding components of the Wg signaling pathway in the eye disc and examine their effects on photoreceptor differentiation by immunohistochemistry.
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Affiliation(s)
- Kevin Legent
- Kimmel Center for Biology and Medicine of the Skirball I nstitute, New York University School of Medicine, Department of Cell Biology, New York, NY, USA
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43
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Podgorski GJ, Bansal M, Flann NS. Regular mosaic pattern development: a study of the interplay between lateral inhibition, apoptosis and differential adhesion. Theor Biol Med Model 2007; 4:43. [PMID: 17974031 PMCID: PMC2203995 DOI: 10.1186/1742-4682-4-43] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2007] [Accepted: 10/31/2007] [Indexed: 11/18/2022] Open
Abstract
Background A significant body of literature is devoted to modeling developmental mechanisms that create patterns within groups of initially equivalent embryonic cells. Although it is clear that these mechanisms do not function in isolation, the timing of and interactions between these mechanisms during embryogenesis is not well known. In this work, a computational approach was taken to understand how lateral inhibition, differential adhesion and programmed cell death can interact to create a mosaic pattern of biologically realistic primary and secondary cells, such as that formed by sensory (primary) and supporting (secondary) cells of the developing chick inner ear epithelium. Results Four different models that interlaced cellular patterning mechanisms in a variety of ways were examined and their output compared to the mosaic of sensory and supporting cells that develops in the chick inner ear sensory epithelium. The results show that: 1) no single patterning mechanism can create a 2-dimensional mosaic pattern of the regularity seen in the chick inner ear; 2) cell death was essential to generate the most regular mosaics, even through extensive cell death has not been reported for the developing basilar papilla; 3) a model that includes an iterative loop of lateral inhibition, programmed cell death and cell rearrangements driven by differential adhesion created mosaics of primary and secondary cells that are more regular than the basilar papilla; 4) this same model was much more robust to changes in homo- and heterotypic cell-cell adhesive differences than models that considered either fewer patterning mechanisms or single rather than iterative use of each mechanism. Conclusion Patterning the embryo requires collaboration between multiple mechanisms that operate iteratively. Interlacing these mechanisms into feedback loops not only refines the output patterns, but also increases the robustness of patterning to varying initial cell states.
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Affiliation(s)
- Gregory J Podgorski
- Biology Department and Center for Integrated Biosystems, Utah State University, Logan UT, USA.
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Wu J, Jenny A, Mirkovic I, Mlodzik M. Frizzled-Dishevelled signaling specificity outcome can be modulated by Diego in Drosophila. Mech Dev 2007; 125:30-42. [PMID: 18065209 DOI: 10.1016/j.mod.2007.10.006] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2007] [Revised: 10/09/2007] [Accepted: 10/11/2007] [Indexed: 11/19/2022]
Abstract
Members of the Frizzled (Fz) family of seven-pass transmembrane receptors are required for the transduction of both Wnt-Fz/beta-catenin and Fz/planar cell polarity (PCP) signals. Although both pathways transduce signals via interactions between Fz and the cytoplasmic protein Dishevelled (Dsh), each pathway has specific and distinct effectors. One explanation for the pathway specificity is that signal-induced conformational changes result in unique Fz-Dsh interactions. Our mutational analyses of Fz-Dsh activities in vivo do however not support this model, since both pathways are affected by all mutations tested. Alternatively, the interaction of Fz or Dsh with other proteins could modulate the signaling outcome. We examined the role of a Dsh-binding PCP molecule, Diego (Dgo), in both Wnt-Fz/beta-catenin and Fz/PCP signaling. Both loss-of-function and gain-of-function results suggest that Dgo promotes Fz-Dsh/PCP signaling at the expense of Wnt-Fz/beta-catenin signaling. Our data suggest that Dgo sequesters Dsh to a functionally distinct Fz/PCP signaling compartment within the cell.
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Affiliation(s)
- Jun Wu
- Developmental & Regenerative Biology, Mt. Sinai School of Medicine, One Gustave L. Levy Place, New York, NY 10029, USA
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Wnt signaling induces differentiation of progenitor cells in organotypic keratinocyte cultures. BMC DEVELOPMENTAL BIOLOGY 2007; 7:9. [PMID: 17306035 PMCID: PMC1821013 DOI: 10.1186/1471-213x-7-9] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/23/2006] [Accepted: 02/17/2007] [Indexed: 01/22/2023]
Abstract
Background Interfollicular skin develops normally only when the activity of the progenitor cells in the basal layer is counterbalanced by the exit of cells into the suprabasal layers, where they differentiate and cornify to establish barrier function. Distinct stem and progenitor compartments have been demonstrated in hair follicles and sebaceous glands, but there are few data to describe the control of interfollicular progenitor cell activity. Wnt signaling has been shown to be an important growth-inducer of stem cell compartments in skin and many other tissues. Results Here, we test the effect of ectopic Wnt1 expression on the behavior of interfollicular progenitor cells in an organotypic culture model, and find that Wnt1 signaling inhibits their growth and promotes terminal differentiation. Conclusion These results are consistent with the phenotypes reported for transgenic mice engineered to have gain or loss of function of Wnt signaling in skin, which would recommend our culture model as an accurate one for molecular analysis. Since it is known that canonical ligands are expressed in skin, it is likely that this pathway normally regulates the balance of growth and differentiation, and suggests it could be important to pathogenesis.
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Singh A, Shi X, Choi KW. Lobe and Serrate are required for cell survival during early eye development in Drosophila. Development 2007; 133:4771-81. [PMID: 17090721 DOI: 10.1242/dev.02686] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Organogenesis involves an initial surge of cell proliferation, leading to differentiation. This is followed by cell death in order to remove extra cells. During early development, there is little or no cell death. However, there is a lack of information concerning the genes required for survival during the early cell-proliferation phase. Here, we show that Lobe (L) and the Notch (N) ligand Serrate (Ser), which are both involved in ventral eye growth, are required for cell survival in the early eye disc. We observed that the loss-of-ventral-eye phenotype in L or Ser mutants is due to the induction of cell death and the upregulation of secreted Wingless (Wg). This loss-of-ventral-eye phenotype can be rescued by (i) increasing the levels of cell death inhibitors, (ii) reducing the levels of Hid-Reaper-Grim complex, or (iii) reducing canonical Wg signaling components. Blocking Jun-N-terminal kinase (JNK) signaling, which can induce caspase-independent cell death, significantly rescued ventral eye loss in L or Ser mutants. However, blocking both caspase-dependent cell death and JNK signaling together showed stronger rescues of the L- or Ser-mutant eye at a 1.5-fold higher frequency. This suggests that L or Ser loss-of-function triggers both caspase-dependent and -independent cell death. Our studies thus identify a mechanism responsible for cell survival in the early eye.
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Affiliation(s)
- Amit Singh
- Department of Molecular and Cellular Biology, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA.
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Thompson BJ, Cohen SM. The Hippo pathway regulates the bantam microRNA to control cell proliferation and apoptosis in Drosophila. Cell 2006; 126:767-74. [PMID: 16923395 DOI: 10.1016/j.cell.2006.07.013] [Citation(s) in RCA: 310] [Impact Index Per Article: 17.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2006] [Revised: 05/12/2006] [Accepted: 07/05/2006] [Indexed: 11/23/2022]
Abstract
The Hippo signaling pathway acts upon the Yorkie transcriptional activator to control tissue growth in Drosophila. Activated Yorkie drives growth by stimulating cell proliferation and inhibiting apoptosis, but how it achieves this is not understood. Yorkie is known to activate Cyclin E (CycE) and the apoptosis inhibitor DIAP1. However, overexpression of these targets is not sufficient to cause tissue overgrowth. Here we show that Yorkie also activates expression of the bantam microRNA, a known regulator of both proliferation and apoptosis. bantam overexpression mimics Yorkie activation while loss of bantam function slows the rate of cell proliferation. bantam is necessary for Yorkie-induced overproliferation and bantam overexpression is sufficient to rescue survival and proliferation of yorkie mutant cells. Finally, we show that bantam levels are regulated during both developmentally programmed proliferation arrest and apoptosis. In summary, the results show that the Hippo pathway regulates expression of bantam to control tissue growth in Drosophila.
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Affiliation(s)
- Barry J Thompson
- European Molecular Biology Laboratory, Meyerhofstrasse 1, Heidelberg 69117, Germany
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Guan J, Li H, Rogulja A, Axelrod JD, Cadigan KM. The Drosophila casein kinase Iepsilon/delta Discs overgrown promotes cell survival via activation of DIAP1 expression. Dev Biol 2006; 303:16-28. [PMID: 17134692 PMCID: PMC2892850 DOI: 10.1016/j.ydbio.2006.10.028] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2006] [Revised: 10/17/2006] [Accepted: 10/18/2006] [Indexed: 01/07/2023]
Abstract
The proper number of cells in developing tissues is achieved by coordinating cell division with apoptosis. In Drosophila, the adult wing is derived from wing imaginal discs, which undergo a period of growth and proliferation during larval stages without much programmed cell death. In this report, we demonstrate that the Drosophila casein kinase Iepsilon/delta, known as Discs overgrown (Dco), is required for maintaining this low level of apoptosis. Expression of dco can suppress the apoptotic activity of Head involution defective (Hid) in the developing eye. Loss of dco in the wing disc results in a dramatic reduction in expression of the caspase inhibitor DIAP1 and a concomitant activation of caspases. The regulation of DIAP1 by Dco occurs by a post-transcriptional mechanism that is independent of hid. Mutant clones of dco are considerably smaller than controls even when apoptosis is inhibited, suggesting that Dco promotes cell division/growth in addition to its role in cell survival. The dco phenotype cannot be explained by defects Wingless (Wg) signaling. We propose that Dco coordinates tissue size by stimulating cell division/growth and blocking apoptosis via activation of DIAP1 expression.
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Affiliation(s)
- Ju Guan
- Department of Molecular, Cellular and Developmental Biology, University of Michigan, Natural Science Building, Ann Arbor MI 48109-1048, USA
| | - Hui Li
- Department of Molecular, Cellular and Developmental Biology, University of Michigan, Natural Science Building, Ann Arbor MI 48109-1048, USA
| | - Ana Rogulja
- Department of Molecular, Cellular and Developmental Biology, University of Michigan, Natural Science Building, Ann Arbor MI 48109-1048, USA
| | - Jeff D. Axelrod
- Department of Pathology, Stanford University School of Medicine, Stanford CA 94305
| | - Ken M. Cadigan
- Department of Molecular, Cellular and Developmental Biology, University of Michigan, Natural Science Building, Ann Arbor MI 48109-1048, USA
- Corresponding author. Fax: +1 734 647-0884. Email address: (K. Cadigan)
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Lim HY, Tomlinson A. Organization of the peripheral fly eye: the roles of Snail family transcription factors in peripheral retinal apoptosis. Development 2006; 133:3529-37. [PMID: 16914498 DOI: 10.1242/dev.02524] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The periphery of the fly eye contains a number of concentrically arranged cellular specializations that are induced by Wingless (Wg) signaling from the surrounding head capsule (HC). One of these is the pigment rim (PR), which is a thick layer of pigment cells that lies directly adjacent to the HC and completely circumscribes the rest of the retina. Many of the cells of the PR are derived from presumptive pigment cells that previously surrounded peripheral ommatidia that subsequently died. Here, we describe the Wgelicited expression of Snail family transcription factors in the eye periphery that directs the ommatidial death and subsequent PR formation. These transcription factors are expressed only in a subset of the ommatidial cells not including the photoreceptors. Yet, the photoreceptors die and, thus, a non-autonomous death signal is released from the Snail-family-expressing cells that direct the death of the photoreceptors. In addition, Wg also elicits a similar peripheral expression of Notum, an enzyme that limits the extent of Wg signaling. Furthermore, we describe a later requirement for Snail family proteins in the 2° and 3° pigment cells throughout the main body of the eye.
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Affiliation(s)
- Hui-Ying Lim
- Department of Pathology, College of Physicians and Surgeons, Columbia University, New York, NY 10032, USA
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Friedrich M. Continuity versus split and reconstitution: exploring the molecular developmental corollaries of insect eye primordium evolution. Dev Biol 2006; 299:310-29. [PMID: 16973149 DOI: 10.1016/j.ydbio.2006.08.027] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2006] [Revised: 07/31/2006] [Accepted: 08/12/2006] [Indexed: 10/24/2022]
Abstract
Holometabolous insects like Drosophila proceed through two phases of visual system development. The embryonic phase generates simple eyes of the larva. The postembryonic phase produces the adult specific compound eyes during late larval development and pupation. In primitive insects, by contrast, eye development persists seemingly continuously from embryogenesis through the end of postembryogenesis. Comparative literature suggests that the evolutionary transition from continuous to biphasic eye development occurred via transient developmental arrest. This review investigates how the developmental arrest model relates to the gene networks regulating larval and adult eye development in Drosophila, and embryonic compound eye development in primitive insects. Consistent with the developmental arrest model, the available data suggest that the determination of the anlage of the rudimentary Drosophila larval eye is homologous to the embryonic specification of the juvenile compound eye in directly developing insects while the Drosophila compound eye primordium is evolutionarily related to the yet little studied stem cell based postembryonic eye primordium of primitive insects.
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Affiliation(s)
- Markus Friedrich
- Department of Biological Sciences, Wayne State University, 5047 Gullen Mall, Detroit, MI 48202, USA.
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