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Shi L, Ma H, Wang J, Ma M, Zhao H, Li Z, Wang JH, Wu S, Zhou Z, Dong MQ, Li Z. An EMC-Hpo-Yki axis maintains intestinal homeostasis under physiological and pathological conditions. Development 2023; 150:dev201958. [PMID: 38031990 DOI: 10.1242/dev.201958] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2023] [Accepted: 11/08/2023] [Indexed: 12/01/2023]
Abstract
Balanced control of stem cell proliferation and differentiation underlines tissue homeostasis. Disruption of tissue homeostasis often results in many diseases. However, how endogenous factors influence the proliferation and differentiation of intestinal stem cells (ISCs) under physiological and pathological conditions remains poorly understood. Here, we find that the evolutionarily conserved endoplasmic reticulum membrane protein complex (EMC) negatively regulates ISC proliferation and intestinal homeostasis. Compromising EMC function in progenitors leads to excessive ISC proliferation and intestinal homeostasis disruption. Mechanistically, the EMC associates with and stabilizes Hippo (Hpo) protein, the key component of the Hpo signaling pathway. In the absence of EMC, Yorkie (Yki) is activated to promote ISC proliferation due to Hpo destruction. The EMC-Hpo-Yki axis also functions in enterocytes to maintain intestinal homeostasis. Importantly, the levels of the EMC are dramatically diminished in tunicamycin-treated animals, leading to Hpo destruction, thereby resulting in intestinal homeostasis disruption due to Yki activation. Thus, our study uncovers the molecular mechanism underlying the action of the EMC in intestinal homeostasis maintenance under physiological and pathological conditions and provides new insight into the pathogenesis of tunicamycin-induced tumorigenesis.
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Affiliation(s)
- Lin Shi
- Laboratory of Stem Cell Biology, College of Life Sciences, Capital Normal University, Beijing 100048, China
| | - Hubing Ma
- Laboratory of Stem Cell Biology, College of Life Sciences, Capital Normal University, Beijing 100048, China
| | - Jinjun Wang
- Laboratory of Stem Cell Biology, College of Life Sciences, Capital Normal University, Beijing 100048, China
| | - Meifang Ma
- Laboratory of Stem Cell Biology, College of Life Sciences, Capital Normal University, Beijing 100048, China
| | - Hang Zhao
- Laboratory of Stem Cell Biology, College of Life Sciences, Capital Normal University, Beijing 100048, China
| | - Zhengran Li
- Laboratory of Stem Cell Biology, College of Life Sciences, Capital Normal University, Beijing 100048, China
| | - Jian-Hua Wang
- National Institute of Biological Sciences, Beijing 102206, China
| | - Shian Wu
- College of Life Sciences, Nankai University, Tianjin 300071, China
| | - Zizhang Zhou
- State Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, Tai'an 271018, China
| | - Meng-Qiu Dong
- National Institute of Biological Sciences, Beijing 102206, China
| | - Zhouhua Li
- Laboratory of Stem Cell Biology, College of Life Sciences, Capital Normal University, Beijing 100048, China
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2
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Tong C, Zhang K, Rong Z, Mo W, Peng Y, Zheng S, Feng QL, Deng H. Alternative splicing of POUM2 regulates embryonic cuticular formation and tanning in Bombyx mori. INSECT SCIENCE 2023; 30:1267-1281. [PMID: 36562105 DOI: 10.1111/1744-7917.13164] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/24/2022] [Revised: 11/17/2022] [Accepted: 11/29/2022] [Indexed: 06/17/2023]
Abstract
Insect cuticle is an apical extracellular matrix produced by the epidermis, tracheal, hind- and foregut epithelia during embryogenesis and renewed during molting and metamorphosis. However, the underlying regulatory mechanism for embryonic cuticle formation remains largely unclear. Here, we investigate the function of the transcription factor POUM2 in the embryonic cuticular formation in Bombyx mori, a model lepidopteran insect. Clustered regularly interspaced palindromic repeats (CRISPR)/CRISPR-associated protein-9-mediated knockout of POUM2 resulted in the defect of cuticular deposition, pigmentation, and sclerotization in the embryos. Differentially expressed transcripts analysis of 7-d-old embryos identified 174 up- or downregulated cuticular protein transcripts, 8 upregulated chitin degradation transcripts, 2 downregulated chitin synthesis transcripts and 48 up- or downregulated transcription factor transcripts in the POUM2-/- embryos. The expression levels of the key factors of the tyrosine metabolic pathway, such as tyrosine hydroxylase (Th), Dopa decarboxylase (DDC), and arylalkylamine N-acetyltransferase (aaNAT), were significantly decreased in the POUM2-/- embryos. POUM2 isoform POUM2-L specifically bound the POU cis-regulatory element (CRE) in the Th promoter and increased the transcription of Th, whereas POUM2-S could not bind the POU CRE, although it also increased the transcription of Th. Heterogeneous nuclear ribonucleoprotein Squid-1 directly bound the POUM2 pre-mRNA (messenger RNA) and inhibited the alternative splicing of POUM2-L to POUM2-S mRNA. These results suggest that POUM2 participates in the cuticular formation by regulating the chitin and cuticular protein synthesis and metabolism, and the cuticular pigmentation and sclerotization by regulating tyrosine metabolism during embryogenesis. This study provides new insights into novel function of POUM2 in embryogenesis.
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Affiliation(s)
- Chunmei Tong
- Guangdong Key Laboratory of Insect Developmental Biology and Applied Technology, Guangzhou Key Laboratory of Insect Development Regulation and Application Research, Institute of Insect Science and Technology & School of Life Sciences, South China Normal University, Guangzhou, China
| | - Kang Zhang
- Guangdong Key Laboratory of Insect Developmental Biology and Applied Technology, Guangzhou Key Laboratory of Insect Development Regulation and Application Research, Institute of Insect Science and Technology & School of Life Sciences, South China Normal University, Guangzhou, China
| | - Zixia Rong
- Guangdong Key Laboratory of Insect Developmental Biology and Applied Technology, Guangzhou Key Laboratory of Insect Development Regulation and Application Research, Institute of Insect Science and Technology & School of Life Sciences, South China Normal University, Guangzhou, China
| | - Wanyu Mo
- Guangdong Key Laboratory of Insect Developmental Biology and Applied Technology, Guangzhou Key Laboratory of Insect Development Regulation and Application Research, Institute of Insect Science and Technology & School of Life Sciences, South China Normal University, Guangzhou, China
| | - Yuling Peng
- Guangdong Key Laboratory of Insect Developmental Biology and Applied Technology, Guangzhou Key Laboratory of Insect Development Regulation and Application Research, Institute of Insect Science and Technology & School of Life Sciences, South China Normal University, Guangzhou, China
| | - Sichun Zheng
- Guangdong Key Laboratory of Insect Developmental Biology and Applied Technology, Guangzhou Key Laboratory of Insect Development Regulation and Application Research, Institute of Insect Science and Technology & School of Life Sciences, South China Normal University, Guangzhou, China
| | - Qi-Li Feng
- Guangdong Key Laboratory of Insect Developmental Biology and Applied Technology, Guangzhou Key Laboratory of Insect Development Regulation and Application Research, Institute of Insect Science and Technology & School of Life Sciences, South China Normal University, Guangzhou, China
| | - Huimin Deng
- Guangdong Key Laboratory of Insect Developmental Biology and Applied Technology, Guangzhou Key Laboratory of Insect Development Regulation and Application Research, Institute of Insect Science and Technology & School of Life Sciences, South China Normal University, Guangzhou, China
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3
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Loker R, Mann RS. Divergent expression of paralogous genes by modification of shared enhancer activity through a promoter-proximal silencer. Curr Biol 2022; 32:3545-3555.e4. [PMID: 35853455 PMCID: PMC9398998 DOI: 10.1016/j.cub.2022.06.069] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2022] [Revised: 05/18/2022] [Accepted: 06/22/2022] [Indexed: 11/16/2022]
Abstract
The duplication of genes and their associated cis-regulatory elements, or enhancers, is a key contributor to genome evolution and biological complexity. Moreover, many paralogs, particularly tandem duplicates, are fixed for long periods of time under the control of shared enhancers. However, in most cases, the mechanism by which gene expression and function diverge following duplication is not known. Here, we dissect the regulation and function of the paralogous nubbin/pdm2 genes during wing development in Drosophila melanogaster. We show that these paralogs play a redundant role in the wing and that their expression relies on a single shared wing enhancer. However, the two genes differ in their ability to respond to this enhancer, with nub responding in all wing progenitor cells and pdm2 only in a small subset. This divergence is a result of a pdm2-specific silencer element at the pdm2 promoter that receives repressive input from the transcription factor Rotund. Repression through this silencer also depends on nub, allowing pdm2 to fully respond to the wing enhancer when nub expression is perturbed and functional compensation to occur. Thus, expression divergence downstream of a shared enhancer arises as a consequence of silencing the promoter of one paralog.
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Affiliation(s)
- Ryan Loker
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY, USA
| | - Richard S Mann
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY, USA; Department of Neuroscience, Department of Systems Biology, Mortimer B. Zuckerman Mind Brain Behavior Institute, Columbia University, New York, NY, USA.
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4
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Zhao H, Ren X, Kong R, Shi L, Li Z, Wang R, Ma R, Zhao H, Liu F, Chang HC, Chen CH, Li Z. Auxilin regulates intestinal stem cell proliferation through EGFR. Stem Cell Reports 2022; 17:1120-1137. [PMID: 35427486 PMCID: PMC9133653 DOI: 10.1016/j.stemcr.2022.03.010] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2020] [Revised: 03/14/2022] [Accepted: 03/15/2022] [Indexed: 12/11/2022] Open
Abstract
Adult tissue homeostasis is maintained by residential stem cells. The proliferation and differentiation of adult stem cells must be tightly balanced to avoid excessive proliferation or premature differentiation. However, how stem cell proliferation is properly controlled remains elusive. Here, we find that auxilin (Aux) restricts intestinal stem cell (ISC) proliferation mainly through EGFR signaling. aux depletion leads to excessive ISC proliferation and midgut homeostasis disruption, which is unlikely caused by defective Notch signaling. Aux is expressed in multiple types of intestinal cells. Interestingly, aux depletion causes a dramatic increase in EGFR signaling, with a strong accumulation of EGFR at the plasma membrane and an increased expression of EGFR ligands in response to tissue stress. Furthermore, Aux co-localizes and associates with EGFR. Finally, blocking EGFR signaling completely suppresses the defects caused by aux depletion. Together, these data demonstrate that Aux mainly safeguards EGFR activation to keep a proper ISC proliferation rate to maintain midgut homeostasis.
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Affiliation(s)
- Hang Zhao
- College of Life Sciences, Capital Normal University, Beijing 100048, China
| | - Xuejing Ren
- College of Life Sciences, Capital Normal University, Beijing 100048, China
| | - Ruiyan Kong
- College of Life Sciences, Capital Normal University, Beijing 100048, China
| | - Lin Shi
- College of Life Sciences, Capital Normal University, Beijing 100048, China
| | - Zhengran Li
- College of Life Sciences, Capital Normal University, Beijing 100048, China
| | - Runqi Wang
- College of Life Sciences, Capital Normal University, Beijing 100048, China
| | - Rui Ma
- Department of Neurology, Capital Medical University, Beijing 100053, China
| | - Huiqing Zhao
- College of Life Sciences, Capital Normal University, Beijing 100048, China
| | - Fuli Liu
- College of Life Sciences, Capital Normal University, Beijing 100048, China
| | - Henry C Chang
- Department of Biological Sciences, Purdue University, West Lafayette, IN 47907, USA
| | - Chun-Hong Chen
- Division of Molecular and Genomic Medicine, National Health Research Institute, 35, Keyan Road, Zhunan Town, Miaoli County 350, Taiwan
| | - Zhouhua Li
- College of Life Sciences, Capital Normal University, Beijing 100048, China.
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5
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Lindblad JL, Tare M, Amcheslavsky A, Shields A, Bergmann A. Non-apoptotic enteroblast-specific role of the initiator caspase Dronc for development and homeostasis of the Drosophila intestine. Sci Rep 2021; 11:2645. [PMID: 33514791 PMCID: PMC7846589 DOI: 10.1038/s41598-021-81261-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2020] [Accepted: 01/05/2021] [Indexed: 02/07/2023] Open
Abstract
The initiator caspase Dronc is the only CARD-domain containing caspase in Drosophila and is essential for apoptosis. Here, we report that homozygous dronc mutant adult animals are short-lived due to the presence of a poorly developed, defective and leaky intestine. Interestingly, this mutant phenotype can be significantly rescued by enteroblast-specific expression of dronc+ in dronc mutant animals, suggesting that proper Dronc function specifically in enteroblasts, one of four cell types in the intestine, is critical for normal development of the intestine. Furthermore, enteroblast-specific knockdown of dronc in adult intestines triggers hyperplasia and differentiation defects. These enteroblast-specific functions of Dronc do not require the apoptotic pathway and thus occur in a non-apoptotic manner. In summary, we demonstrate that an apoptotic initiator caspase has a very critical non-apoptotic function for normal development and for the control of the cell lineage in the adult midgut and therefore for proper physiology and homeostasis.
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Affiliation(s)
- Jillian L Lindblad
- Department of Molecular, Cell and Cancer Biology, University of Massachusetts Medical School, 364 Plantation Street, Worcester, MA, 01605, USA
| | - Meghana Tare
- Department of Biological Sciences, Birla Institute of Technology and Science, Pilani, Pilani, Rajasthan, 333031, India
| | - Alla Amcheslavsky
- University of Massachusetts Medical School, MassBiologics, 460 Walk Hill Road, Boston, MA, USA
| | - Alicia Shields
- Department of Molecular, Cell and Cancer Biology, University of Massachusetts Medical School, 364 Plantation Street, Worcester, MA, 01605, USA
| | - Andreas Bergmann
- Department of Molecular, Cell and Cancer Biology, University of Massachusetts Medical School, 364 Plantation Street, Worcester, MA, 01605, USA.
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6
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Tang X, Engström Y. Regulation of immune and tissue homeostasis by Drosophila POU factors. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2019; 109:24-30. [PMID: 30954681 DOI: 10.1016/j.ibmb.2019.04.003] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/09/2018] [Revised: 03/17/2019] [Accepted: 04/01/2019] [Indexed: 06/09/2023]
Abstract
The innate immune system of insects deploys both cellular and humoral reactions in immunocompetent tissues for protection of insects against a variety of infections, including bacteria, fungi, and viruses. Transcriptional regulation of genes encoding antimicrobial peptides (AMPs), cytokines, and other immune effectors plays a pivotal role in maintenance of immune homeostasis both prior to and after infections. The POU/Oct transcription factor family is a subclass of the homeodomain proteins present in all metazoans. POU factors are involved in regulation of development, metabolism and immunity. Their role in regulation of immune functions has recently become evident, and involves control of tissue-specific, constitutive expression of immune effectors in barrier epithelia as well as positive and negative control of immune responses in gut and fat body. In addition, they have been shown to affect the composition of gut microbiota and play a role in regulation of intestinal stem cell activities. In this review, we summarize the current knowledge of how POU transcription factors control Drosophila immune homeostasis in healthy and infected insects. The role of POU factor isoform specific regulation of stem cell activities in Drosophila and mammals is also discussed.
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Affiliation(s)
- Xiongzhuo Tang
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, SE-10691, Stockholm, Sweden
| | - Ylva Engström
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, SE-10691, Stockholm, Sweden.
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7
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Izumi Y, Furuse K, Furuse M. Septate junctions regulate gut homeostasis through regulation of stem cell proliferation and enterocyte behavior in Drosophila. J Cell Sci 2019; 132:jcs.232108. [DOI: 10.1242/jcs.232108] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2019] [Accepted: 08/15/2019] [Indexed: 12/27/2022] Open
Abstract
Smooth septate junctions (sSJs) contribute to the epithelial barrier, which restricts leakage of solutes through the paracellular route of epithelial cells in the Drosophila midgut. We previously identified three sSJ-associated membrane proteins, Ssk, Mesh, and Tsp2A, and showed that these proteins were required for sSJ formation and intestinal barrier function in the larval midgut. Here, we investigated the roles of sSJs in the Drosophila adult midgut. Depletion of any of the sSJ-proteins from enterocytes resulted in remarkably shortened lifespan and intestinal barrier dysfunction in flies. Interestingly, the sSJ-protein-deficient flies showed intestinal hypertrophy accompanied by accumulation of morphologically abnormal enterocytes. The phenotype was associated with increased stem cell proliferation and activation of the MAP kinase and Jak-Stat pathways in stem cells. Loss of cytokines Unpaired2 and Unpaired3, which are involved in Jak-Stat pathway activation, reduced the intestinal hypertrophy, but not the increased stem cell proliferation, in flies lacking Mesh. The present findings suggest that SJs play a crucial role in maintaining tissue homeostasis through regulation of stem cell proliferation and enterocyte behavior in the Drosophila adult midgut.
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Affiliation(s)
- Yasushi Izumi
- Division of Cell Structure, National Institute for Physiological Sciences, Okazaki, Japan
- Department of Physiological Sciences, SOKENDAI, Okazaki, Japan
| | - Kyoko Furuse
- Division of Cell Structure, National Institute for Physiological Sciences, Okazaki, Japan
| | - Mikio Furuse
- Division of Cell Structure, National Institute for Physiological Sciences, Okazaki, Japan
- Department of Physiological Sciences, SOKENDAI, Okazaki, Japan
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8
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Averbukh I, Lai SL, Doe CQ, Barkai N. A repressor-decay timer for robust temporal patterning in embryonic Drosophila neuroblast lineages. eLife 2018; 7:38631. [PMID: 30526852 PMCID: PMC6303102 DOI: 10.7554/elife.38631] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2018] [Accepted: 12/10/2018] [Indexed: 11/13/2022] Open
Abstract
Biological timers synchronize patterning processes during embryonic development. In the Drosophila embryo, neural progenitors (neuroblasts; NBs) produce a sequence of unique neurons whose identities depend on the sequential expression of temporal transcription factors (TTFs). The stereotypy and precision of NB lineages indicate reproducible TTF timer progression. We combine theory and experiments to define the timer mechanism. The TTF timer is commonly described as a relay of activators, but its regulatory circuit is also consistent with a repressor-decay timer, where TTF expression begins when its repressor decays. Theory shows that repressor-decay timers are more robust to parameter variations than activator-relay timers. This motivated us to experimentally compare the relative importance of the relay and decay interactions in vivo. Comparing WT and mutant NBs at high temporal resolution, we show that the TTF sequence progresses primarily by repressor-decay. We suggest that need for robust performance shapes the evolutionary-selected designs of biological circuits.
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Affiliation(s)
- Inna Averbukh
- Department of Molecular Genetics, Weizmann institute of science, Rehovot, Israel
| | - Sen-Lin Lai
- Institute of Neuroscience, Institute of Molecular Biology, Howard Hughes Medical Institute, University of Oregon, Eugene, United States
| | - Chris Q Doe
- Institute of Neuroscience, Institute of Molecular Biology, Howard Hughes Medical Institute, University of Oregon, Eugene, United States
| | - Naama Barkai
- Department of Molecular Genetics, Weizmann institute of science, Rehovot, Israel
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9
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Mattila J, Kokki K, Hietakangas V, Boutros M. Stem Cell Intrinsic Hexosamine Metabolism Regulates Intestinal Adaptation to Nutrient Content. Dev Cell 2018; 47:112-121.e3. [PMID: 30220570 PMCID: PMC6179903 DOI: 10.1016/j.devcel.2018.08.011] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2017] [Revised: 07/07/2018] [Accepted: 08/14/2018] [Indexed: 02/08/2023]
Abstract
The intestine is an organ with an exceptionally high rate of cell turnover, and perturbations in this process can lead to severe diseases such as cancer or intestinal atrophy. Nutrition has a profound impact on intestinal volume and cellular architecture. However, how intestinal homeostasis is maintained in fluctuating dietary conditions remains insufficiently understood. By utilizing the Drosophila midgut model, we reveal a novel stem cell intrinsic mechanism coupling cellular metabolism with stem cell extrinsic growth signal. Our results show that intestinal stem cells (ISCs) employ the hexosamine biosynthesis pathway (HBP) to monitor nutritional status. Elevated activity of HBP promotes Warburg effect-like metabolic reprogramming required for adjusting the ISC division rate according to nutrient content. Furthermore, HBP activity is an essential facilitator for insulin signaling-induced ISC proliferation. In conclusion, ISC intrinsic hexosamine synthesis regulates metabolic pathway activities and defines the stem cell responsiveness to niche-derived growth signals. HBP is a mediator of Drosophila midgut adaptation to nutrient content ISC intrinsic HBP is a necessary and sufficient driver of stem cell divisions HBP activity regulates a Warburg-like metabolic reprogramming of the intestine HBP activity determines the output of InR signaling of the ISCs
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Affiliation(s)
- Jaakko Mattila
- German Cancer Research Center, Division of Signaling and Functional Genomics and Heidelberg University, Heidelberg 69120, Germany
| | - Krista Kokki
- Faculty of Biological and Environmental Sciences, University of Helsinki, Helsinki 00790, Finland; Institute of Biotechnology, University of Helsinki, Helsinki 00790, Finland
| | - Ville Hietakangas
- Faculty of Biological and Environmental Sciences, University of Helsinki, Helsinki 00790, Finland; Institute of Biotechnology, University of Helsinki, Helsinki 00790, Finland
| | - Michael Boutros
- German Cancer Research Center, Division of Signaling and Functional Genomics and Heidelberg University, Heidelberg 69120, Germany.
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10
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Ross J, Kuzin A, Brody T, Odenwald WF. Mutational analysis of a Drosophila neuroblast enhancer governing nubbin expression during CNS development. Genesis 2018; 56:e23237. [PMID: 30005136 PMCID: PMC6175444 DOI: 10.1002/dvg.23237] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2018] [Revised: 06/07/2018] [Accepted: 06/22/2018] [Indexed: 11/17/2022]
Abstract
While developmental studies of Drosophila neural stem cell lineages have identified transcription factors (TFs) important to cell identity decisions, currently only an incomplete understanding exists of the cis‐regulatory elements that control the dynamic expression of these TFs. Our previous studies have identified multiple enhancers that regulate the POU‐domain TF paralogs nubbin and pdm‐2 genes. Evolutionary comparative analysis of these enhancers reveals that they each contain multiple conserved sequence blocks (CSBs) that span TF DNA‐binding sites for known regulators of neuroblast (NB) gene expression in addition to novel sequences. This study functionally analyzes the conserved DNA sequence elements within a NB enhancer located within the nubbin gene and highlights a high level of complexity underlying enhancer structure. Mutational analysis has revealed CSBs that are important for enhancer activation and silencing in the developing CNS. We have also observed that adjusting the number and relative positions of the TF binding sites within these CSBs alters enhancer function.
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Affiliation(s)
- Jermaine Ross
- Neural Cell-Fate Determinants Section, NINDS, NIH, Bethesda, Maryland
| | - Alexander Kuzin
- Neural Cell-Fate Determinants Section, NINDS, NIH, Bethesda, Maryland
| | - Thomas Brody
- Neural Cell-Fate Determinants Section, NINDS, NIH, Bethesda, Maryland
| | - Ward F Odenwald
- Neural Cell-Fate Determinants Section, NINDS, NIH, Bethesda, Maryland
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11
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Bao R, Dia SE, Issa HA, Alhusein D, Friedrich M. Comparative Evidence of an Exceptional Impact of Gene Duplication on the Developmental Evolution of Drosophila and the Higher Diptera. Front Ecol Evol 2018. [DOI: 10.3389/fevo.2018.00063] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
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12
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Tang X, Zhao Y, Buchon N, Engström Y. The POU/Oct Transcription Factor Nubbin Controls the Balance of Intestinal Stem Cell Maintenance and Differentiation by Isoform-Specific Regulation. Stem Cell Reports 2018; 10:1565-1578. [PMID: 29681543 PMCID: PMC5995344 DOI: 10.1016/j.stemcr.2018.03.014] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2017] [Revised: 03/19/2018] [Accepted: 03/20/2018] [Indexed: 12/19/2022] Open
Abstract
Drosophila POU/Oct transcription factors are required for many developmental processes, but their putative regulation of adult stem cell activity has not been investigated. Here, we show that Nubbin (Nub)/Pdm1, homologous to mammalian OCT1/POU2F1 and related to OCT4/POU5F1, is expressed in gut epithelium progenitor cells. We demonstrate that the nub-encoded protein isoforms, Nub-PB and Nub-PD, play opposite roles in the regulation of intestinal stem cell (ISC) maintenance and differentiation. Depletion of Nub-PB in progenitor cells increased ISC proliferation by derepression of escargot expression. Conversely, loss of Nub-PD reduced ISC proliferation, suggesting that this isoform is necessary for ISC maintenance, analogous to mammalian OCT4/POU5F1 functions. Furthermore, Nub-PB is required in enteroblasts to promote differentiation, and it acts as a tumor suppressor of Notch RNAi-driven hyperplasia. We suggest that a dynamic and well-tuned expression of Nub isoforms in progenitor cells is required for maintaining gut epithelium homeostasis. Drosophila nubbin (nub) is expressed in adult midgut progenitor cells The Nub-PB isoform drives differentiation and acts as a tumor suppressor The Nub-PD isoform maintains intestinal stem cell proliferation Nub-PD and Nub-PB regulate stem cell proliferation antagonistically
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Affiliation(s)
- Xiongzhuo Tang
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, Stockholm 10691, Sweden
| | - Yunpo Zhao
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, Stockholm 10691, Sweden
| | - Nicolas Buchon
- Department of Entomology, Cornell University, Ithaca, NY 14853, USA
| | - Ylva Engström
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, Stockholm 10691, Sweden.
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13
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Suong DNA, Shimaji K, Pyo JH, Park JS, Yoshida H, Yoo MA, Yamaguchi M. Overexpression of dJmj differentially affects intestinal stem cells and differentiated enterocytes. Cell Signal 2018; 42:194-210. [DOI: 10.1016/j.cellsig.2017.10.017] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2017] [Revised: 10/19/2017] [Accepted: 10/29/2017] [Indexed: 01/17/2023]
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14
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Perea D, Guiu J, Hudry B, Konstantinidou C, Milona A, Hadjieconomou D, Carroll T, Hoyer N, Natarajan D, Kallijärvi J, Walker JA, Soba P, Thapar N, Burns AJ, Jensen KB, Miguel-Aliaga I. Ret receptor tyrosine kinase sustains proliferation and tissue maturation in intestinal epithelia. EMBO J 2017; 36:3029-3045. [PMID: 28899900 PMCID: PMC5641678 DOI: 10.15252/embj.201696247] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2016] [Revised: 07/26/2017] [Accepted: 07/28/2017] [Indexed: 01/25/2023] Open
Abstract
Expression of the Ret receptor tyrosine kinase is a defining feature of enteric neurons. Its importance is underscored by the effects of its mutation in Hirschsprung disease, leading to absence of gut innervation and severe gastrointestinal symptoms. We report a new and physiologically significant site of Ret expression in the intestine: the intestinal epithelium. Experiments in Drosophila indicate that Ret is expressed both by enteric neurons and adult intestinal epithelial progenitors, which require Ret to sustain their proliferation. Mechanistically, Ret is engaged in a positive feedback loop with Wnt/Wingless signalling, modulated by Src and Fak kinases. We find that Ret is also expressed by the developing intestinal epithelium of mice, where its expression is maintained into the adult stage in a subset of enteroendocrine/enterochromaffin cells. Mouse organoid experiments point to an intrinsic role for Ret in promoting epithelial maturation and regulating Wnt signalling. Our findings reveal evolutionary conservation of the positive Ret/Wnt signalling feedback in both developmental and homeostatic contexts. They also suggest an epithelial contribution to Ret loss‐of‐function disorders such as Hirschsprung disease.
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Affiliation(s)
- Daniel Perea
- MRC London Institute of Medical Sciences, Imperial College London, London, UK
| | - Jordi Guiu
- BRIC-Biotech Research and Innovation Centre, University of Copenhagen, Copenhagen N, Denmark
| | - Bruno Hudry
- MRC London Institute of Medical Sciences, Imperial College London, London, UK
| | | | - Alexandra Milona
- MRC London Institute of Medical Sciences, Imperial College London, London, UK
| | - Dafni Hadjieconomou
- MRC London Institute of Medical Sciences, Imperial College London, London, UK
| | - Thomas Carroll
- MRC London Institute of Medical Sciences, Imperial College London, London, UK
| | - Nina Hoyer
- Center for Molecular Neurobiology, University Medical Center Hamburg-Eppendorf (UKE), University of Hamburg, Hamburg, Germany
| | - Dipa Natarajan
- Stem Cells and Regenerative Medicine, UCL Institute of Child Health, London, UK
| | - Jukka Kallijärvi
- Institute of Biotechnology, University of Helsinki, Helsinki, Finland
| | - James A Walker
- Center for Human Genetic Research, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
| | - Peter Soba
- Center for Molecular Neurobiology, University Medical Center Hamburg-Eppendorf (UKE), University of Hamburg, Hamburg, Germany
| | - Nikhil Thapar
- Stem Cells and Regenerative Medicine, UCL Institute of Child Health, London, UK
| | - Alan J Burns
- Stem Cells and Regenerative Medicine, UCL Institute of Child Health, London, UK
| | - Kim B Jensen
- BRIC-Biotech Research and Innovation Centre, University of Copenhagen, Copenhagen N, Denmark.,The Danish Stem Cell Center (Danstem), Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Irene Miguel-Aliaga
- MRC London Institute of Medical Sciences, Imperial College London, London, UK
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15
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Corty MM, Tam J, Grueber WB. Dendritic diversification through transcription factor-mediated suppression of alternative morphologies. Development 2016; 143:1351-62. [PMID: 27095495 DOI: 10.1242/dev.130906] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2015] [Accepted: 02/25/2016] [Indexed: 01/23/2023]
Abstract
Neurons display a striking degree of functional and morphological diversity, and the developmental mechanisms that underlie diversification are of significant interest for understanding neural circuit assembly and function. We find that the morphology of Drosophila sensory neurons is diversified through a series of suppressive transcriptional interactions involving the POU domain transcription factors Pdm1 (Nubbin) and Pdm2, the homeodomain transcription factor Cut, and the transcriptional regulators Scalloped and Vestigial. Pdm1 and Pdm2 are expressed in a subset of proprioceptive sensory neurons and function to inhibit dendrite growth and branching. A subset of touch receptors show a capacity to express Pdm1/2, but Cut represses this expression and promotes more complex dendritic arbors. Levels of Cut expression are diversified in distinct sensory neurons by selective expression of Scalloped and Vestigial. Different levels of Cut impact dendritic complexity and, consistent with this, we show that Scalloped and Vestigial suppress terminal dendritic branching. This transcriptional hierarchy therefore acts to suppress alternative morphologies to diversify three distinct types of somatosensory neurons.
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Affiliation(s)
- Megan M Corty
- Department of Neuroscience, Columbia University Medical Center, 630 W. 168th St. P&S 12-403, New York, NY 10032, USA Department of Physiology and Cellular Biophysics, Columbia University Medical Center, 630 W. 168th St. P&S 12-403, New York, NY 10032, USA
| | - Justina Tam
- Department of Physiology and Cellular Biophysics, Columbia University Medical Center, 630 W. 168th St. P&S 12-403, New York, NY 10032, USA
| | - Wesley B Grueber
- Department of Neuroscience, Columbia University Medical Center, 630 W. 168th St. P&S 12-403, New York, NY 10032, USA Department of Physiology and Cellular Biophysics, Columbia University Medical Center, 630 W. 168th St. P&S 12-403, New York, NY 10032, USA
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16
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Origin and dynamic lineage characteristics of the developing Drosophila midgut stem cells. Dev Biol 2016; 416:347-60. [PMID: 27321560 DOI: 10.1016/j.ydbio.2016.06.018] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2015] [Revised: 06/14/2016] [Accepted: 06/15/2016] [Indexed: 01/01/2023]
Abstract
Proliferating intestinal stem cells (ISCs) generate all cell types of the Drosophila midgut, including enterocytes, endocrine cells, and gland cells (e.g., copper cells), throughout the lifetime of the animal. Among the signaling mechanisms controlling the balance between ISC self-renewal and the production of different cell types, Notch (N) plays a pivotal role. In this paper we investigated the emergence of ISCs during metamorphosis and the role of N in this process. Precursors of the Drosophila adult intestinal stem cells (pISCs) can be first detected within the pupal midgut during the first hours after onset of metamorphosis as motile mesenchymal cells. pISCs perform 2-3 rounds of parasynchronous divisions. The first mitosis yields only an increase in pISC number. During the following rounds of mitosis, dividing pISCs give rise to more pISCs, as well as the endocrine cells that populate the midgut of the eclosing fly. Enterocytes do not appear among the pISC progeny until around the time of eclosion. The "proendocrine" gene prospero (pros), expressed from mid-pupal stages onward in pISCs, is responsible to advance the endocrine fate in these cells; following removal of pros, pISCs continue to proliferate, but endocrine cells do not form. Conversely, the onset of N activity that occurs around the stage when pros comes on restricts pros expression among pISCs. Loss of N abrogates proliferation and switches on an endocrine fate among all pISCs. Our results suggest that a switch depending on the activity of N and pros acts at the level of the pISC to decide between continued proliferation and endocrine differentiation.
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17
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The sexual identity of adult intestinal stem cells controls organ size and plasticity. Nature 2016; 530:344-8. [PMID: 26887495 PMCID: PMC4800002 DOI: 10.1038/nature16953] [Citation(s) in RCA: 119] [Impact Index Per Article: 14.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2015] [Accepted: 12/21/2015] [Indexed: 01/01/2023]
Abstract
Sex differences in physiology and disease susceptibility are commonly attributed to developmental and/or hormonal factors, but there is increasing realisation that cell-intrinsic mechanisms play important and persistent roles1,2. Here we use the Drosophila melanogaster intestine to investigate the nature and significance of cellular sex in an adult somatic organ in vivo. We find that the adult intestinal epithelium is a cellular mosaic of different sex differentiation pathways, and displays extensive sex differences in expression of genes with roles in growth and metabolism. Cell-specific reversals of the sexual identity of adult intestinal stem cells uncover its key roles in controlling organ size, its reproductive plasticity and its response to genetically induced tumours. Unlike previous examples of sexually dimorphic somatic stem cell activity, the sex differences in intestinal stem cell behaviour arise from intrinsic mechanisms, which control cell cycle duration and involve a new doublesex- and fruitless-independent branch of the sex differentiation pathway downstream of transformer. Together, our findings indicate that the plasticity of an adult somatic organ is reversibly controlled by its sexual identity, imparted by a new mechanism that may be active in more tissues than previously recognised.
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Tian A, Benchabane H, Wang Z, Ahmed Y. Regulation of Stem Cell Proliferation and Cell Fate Specification by Wingless/Wnt Signaling Gradients Enriched at Adult Intestinal Compartment Boundaries. PLoS Genet 2016; 12:e1005822. [PMID: 26845150 PMCID: PMC4742051 DOI: 10.1371/journal.pgen.1005822] [Citation(s) in RCA: 57] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2015] [Accepted: 12/31/2015] [Indexed: 01/12/2023] Open
Abstract
Intestinal stem cell (ISC) self-renewal and proliferation are directed by Wnt/β-catenin signaling in mammals, whereas aberrant Wnt pathway activation in ISCs triggers the development of human colorectal carcinoma. Herein, we have utilized the Drosophila midgut, a powerful model for ISC regulation, to elucidate the mechanisms by which Wingless (Wg)/Wnt regulates intestinal homeostasis and development. We provide evidence that the Wg signaling pathway, activation of which peaks at each of the major compartment boundaries of the adult intestine, has essential functions. Wg pathway activation in the intestinal epithelium is required not only to specify cell fate near compartment boundaries during development, but also to control ISC proliferation within compartments during homeostasis. Further, in contrast with the previous focus on Wg pathway activation within ISCs, we demonstrate that the primary mechanism by which Wg signaling regulates ISC proliferation during homeostasis is non-autonomous. Activation of the Wg pathway in absorptive enterocytes is required to suppress JAK-STAT signaling in neighboring ISCs, and thereby their proliferation. We conclude that Wg signaling gradients have essential roles during homeostasis and development of the adult intestine, non-autonomously controlling stem cell proliferation inside compartments, and autonomously specifying cell fate near compartment boundaries. The highly conserved Wingless/Wnt signal transduction pathway directs many cellular processes in metazoans and its deregulation underlies numerous human congenital diseases and cancers. Most notably, more than 80% of colon cancers arise from aberrant activation of the Wnt pathway. A better understanding of how Wnt signaling functions in the intestinal stem cells (ISCs) during homeostasis and in disease states is thus critical. The Drosophila digestive tract provides a powerful genetic model and an entry point to study these questions. Here, we find that the Wg ligand and pathway activation are enriched at Drosophila intestinal compartment boundaries and are essential for development and homeostasis of the adult gut. During homeostasis, Wg signaling in enterocytes is required to prevent the overproliferation of ISCs non-autonomously. In addition, during development, Wg signaling ensures proper cell fate specification near compartment boundaries. These findings provide insight into the mechanisms underlying the Wg-dependent regulation of adult intestinal function.
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Affiliation(s)
- Ai Tian
- Department of Genetics and the Norris Cotton Cancer Center, Geisel School of Medicine at Dartmouth College, Hanover, New Hampshire, United States of America
| | - Hassina Benchabane
- Department of Genetics and the Norris Cotton Cancer Center, Geisel School of Medicine at Dartmouth College, Hanover, New Hampshire, United States of America
| | - Zhenghan Wang
- Department of Genetics and the Norris Cotton Cancer Center, Geisel School of Medicine at Dartmouth College, Hanover, New Hampshire, United States of America
| | - Yashi Ahmed
- Department of Genetics and the Norris Cotton Cancer Center, Geisel School of Medicine at Dartmouth College, Hanover, New Hampshire, United States of America
- * E-mail:
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19
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Guo Z, Ohlstein B. Stem cell regulation. Bidirectional Notch signaling regulates Drosophila intestinal stem cell multipotency. Science 2016; 350:350/6263/aab0988. [PMID: 26586765 DOI: 10.1126/science.aab0988] [Citation(s) in RCA: 138] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Drosophila intestinal stem cells (ISCs) generate enterocytes (ECs) and enteroendocrine (ee) cells. Previous work suggests that different levels of the Notch ligand Delta (Dl) in ISCs unidirectionally activate Notch in daughters to control multipotency. However, the mechanisms driving different outcomes remain unknown. We found that during ee cell formation, the ee cell marker Prospero localizes to the basal side of dividing ISCs. After asymmetric division, the ee daughter cell acts as a source of Dl that induces low Notch activity in the ISC to maintain identity. Alternatively, ISCs expressing Dl induce high Notch activity in daughter cells to promote EC formation. Our data reveal a conserved role for Notch in Drosophila and mammalian ISC maintenance and suggest that bidirectional Notch signaling may regulate multipotency in other systems.
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Affiliation(s)
- Zheng Guo
- Department of Genetics and Development, Columbia University Medical Center, New York, NY 10032, USA
| | - Benjamin Ohlstein
- Department of Genetics and Development, Columbia University Medical Center, New York, NY 10032, USA.
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20
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cis-regulatory analysis of the Drosophila pdm locus reveals a diversity of neural enhancers. BMC Genomics 2015; 16:700. [PMID: 26377945 PMCID: PMC4574355 DOI: 10.1186/s12864-015-1897-2] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2015] [Accepted: 09/02/2015] [Indexed: 11/15/2022] Open
Abstract
Background One of the major challenges in developmental biology is to understand the regulatory events that generate neuronal diversity. During Drosophila embryonic neural lineage development, cellular temporal identity is established in part by a transcription factor (TF) regulatory network that mediates a cascade of cellular identity decisions. Two of the regulators essential to this network are the POU-domain TFs Nubbin and Pdm-2, encoded by adjacent genes collectively known as pdm. The focus of this study is the discovery and characterization of cis-regulatory DNA that governs their expression. Results Phylogenetic footprinting analysis of a 125 kb genomic region that spans the pdm locus identified 116 conserved sequence clusters. To determine which of these regions function as cis-regulatory enhancers that regulate the dynamics of pdm gene expression, we tested each for in vivo enhancer activity during embryonic development and postembryonic neurogenesis. Our screen revealed 77 unique enhancers positioned throughout the noncoding region of the pdm locus. Many of these activated neural-specific gene expression during different developmental stages and many drove expression in overlapping patterns. Sequence comparisons of functionally related enhancers that activate overlapping expression patterns revealed that they share conserved elements that can be predictive of enhancer behavior. To facilitate data accessibility, the results of our analysis are catalogued in cisPatterns, an online database of the structure and function of these and other Drosophila enhancers. Conclusions These studies reveal a diversity of modular enhancers that most likely regulate pdm gene expression during embryonic and adult development, highlighting a high level of temporal and spatial expression specificity. In addition, we discovered clusters of functionally related enhancers throughout the pdm locus. A subset of these enhancers share conserved elements including sequences that correspond to known TF DNA binding sites. Although comparative analysis of the nubbin and pdm-2 encoding sequences indicate that these two genes most likely arose from a duplication event, we found only partial evidence of sequence duplication between their enhancers, suggesting that after the putative duplication their cis-regulatory DNA diverged at a higher rate than their coding sequences. Electronic supplementary material The online version of this article (doi:10.1186/s12864-015-1897-2) contains supplementary material, which is available to authorized users.
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21
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Dantoft W, Davis MM, Lindvall JM, Tang X, Uvell H, Junell A, Beskow A, Engström Y. The Oct1 homolog Nubbin is a repressor of NF-κB-dependent immune gene expression that increases the tolerance to gut microbiota. BMC Biol 2013; 11:99. [PMID: 24010524 PMCID: PMC3849502 DOI: 10.1186/1741-7007-11-99] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2013] [Accepted: 08/30/2013] [Indexed: 11/10/2022] Open
Abstract
Background Innate immune responses are evolutionarily conserved processes that provide crucial protection against invading organisms. Gene activation by potent NF-κB transcription factors is essential both in mammals and Drosophila during infection and stress challenges. If not strictly controlled, this potent defense system can activate autoimmune and inflammatory stress reactions, with deleterious consequences for the organism. Negative regulation to prevent gene activation in healthy organisms, in the presence of the commensal gut flora, is however not well understood. Results We show that the Drosophila homolog of mammalian Oct1/POU2F1 transcription factor, called Nubbin (Nub), is a repressor of NF-κB/Relish-driven antimicrobial peptide gene expression in flies. In nub1 mutants, which lack Nub-PD protein, excessive expression of antimicrobial peptide genes occurs in the absence of infection, leading to a significant reduction of the numbers of cultivatable gut commensal bacteria. This aberrant immune gene expression was effectively blocked by expression of Nub from a transgene. We have identified an upstream regulatory region, containing a cluster of octamer sites, which is required for repression of antimicrobial peptide gene expression in healthy flies. Chromatin immunoprecipitation experiments demonstrated that Nub binds to octamer-containing promoter fragments of several immune genes. Gene expression profiling revealed that Drosophila Nub negatively regulates many genes that are involved in immune and stress responses, while it is a positive regulator of genes involved in differentiation and metabolism. Conclusions This study demonstrates that a large number of genes that are activated by NF-κB/Relish in response to infection are normally repressed by the evolutionarily conserved Oct/POU transcription factor Nub. This prevents uncontrolled gene activation and supports the existence of a normal gut flora. We suggest that Nub protein plays an ancient role, shared with mammalian Oct/POU transcription factors, to moderate responses to immune challenge, thereby increasing the tolerance to biotic stress.
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Affiliation(s)
- Widad Dantoft
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, SE-106 91, Stockholm, Sweden.
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22
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He H, Noll M. Differential and redundant functions of gooseberry and gooseberry neuro in the central nervous system and segmentation of the Drosophila embryo. Dev Biol 2013; 382:209-23. [PMID: 23886579 DOI: 10.1016/j.ydbio.2013.05.017] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2013] [Revised: 05/10/2013] [Accepted: 05/14/2013] [Indexed: 01/25/2023]
Abstract
The gooseberry locus of Drosophila consists of two homologous Pax genes, gooseberry neuro (gsbn) and gooseberry (gsb). Originally characterized by genetics as a single segment-polarity gene, its role in segmentation has been enigmatic, as only deficiencies uncovering both genes showed a strong segmentation phenotype while mutants of gsb did not. To solve this conundrum and assay for differential roles of gsbn and gsb, we have obtained by homologous recombination for the first time null mutants of either gene as well as a deficiency inactivating only gsbn and gsb. Our analysis shows that (i) gsbn null mutants are subviable while all surviving males and most females are sterile; (ii) gsb and gsbn share overlapping functions in segmentation and the CNS, in which gsbn largely, but not completely depends on the transcriptional activation by the product of gsb; (iii) as a consequence, in the absence of gsbn, gsb becomes haploinsufficient for its function in the CNS, and gsbn(-/-)gsb(-/+) mutants die as larvae. Such mutants display defects in the proper specification of the SNa branch of the segmental nerve, which appears intact in gsbn(-/-) mutants. Lineage analysis in the embryonic CNS showed that gsbn is expressed in the entire lineage derived from NB5-4, which generates 4 or 5 motoneurons whose axons are part of the SNa branch and all of which except one also express BarH1. Analysis of gsbn(-/-)gsb(-/+) clones originating from NB5-4 further suggests that gsb and gsbn specify the SNa fate and concomitantly repress the SNc fate in this lineage and that their products activate BarH1 transcription. Specification of the SNa fate by Gsb and Gsbn occurs mainly at the NB and GMC stage. However, the SNa mutant phenotype can be rescued by providing Gsbn as late as at the postmitotic stage. The hierarchical relationship between gsb and gsbn, the haploinsufficiency of gsb in gsbn mutants, and their redundant roles in the epidermis and CNS are discussed. A model is proposed how selection for both genes occurred after their duplication during evolution.
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Affiliation(s)
- Haihuai He
- Institute of Molecular Life Sciences, University of Zürich, Winterthurerstr. 190, CH-8057 Zürich, Switzerland
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23
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Takashima S, Paul M, Aghajanian P, Younossi-Hartenstein A, Hartenstein V. Migration of Drosophila intestinal stem cells across organ boundaries. Development 2013; 140:1903-11. [PMID: 23571215 DOI: 10.1242/dev.082933] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
All components of the Drosophila intestinal tract, including the endodermal midgut and ectodermal hindgut/Malpighian tubules, maintain populations of dividing stem cells. In the midgut and hindgut, these stem cells originate from within larger populations of intestinal progenitors that proliferate during the larval stage and form the adult intestine during metamorphosis. The origin of stem cells found in the excretory Malpighian tubules ('renal stem cells') has not been established. In this paper, we investigate the migration patterns of intestinal progenitors that take place during metamorphosis. Our data demonstrate that a subset of adult midgut progenitors (AMPs) move posteriorly to form the adult ureters and, consecutively, the renal stem cells. Inhibiting cell migration by AMP-directed expression of a dominant-negative form of Rac1 protein results in the absence of stem cells in the Malpighian tubules. As the majority of the hindgut progenitor cells migrate posteriorly and differentiate into hindgut enterocytes, a group of the progenitor cells, unexpectedly, invades anteriorly into the midgut territory. Consequently, these progenitor cells differentiate into midgut enterocytes. The midgut determinant GATAe is required for the differentiation of midgut enterocytes derived from hindgut progenitors. Wingless signaling acts to balance the proportion of hindgut progenitors that differentiate as midgut versus hindgut enterocytes. Our findings indicate that a stable boundary between midgut and hindgut/Malpighian tubules is not established during early embryonic development; instead, pluripotent progenitor populations cross in between these organs in both directions, and are able to adopt the fate of the organ in which they come to reside.
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Affiliation(s)
- Shigeo Takashima
- Department of Molecular Cell and Developmental Biology, University of California-Los Angeles, CA 90095, USA
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24
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Chen CK, Chen WY, Chien CT. The POU-domain protein Pdm3 regulates axonal targeting of R neurons in the Drosophila ellipsoid body. Dev Neurobiol 2012; 72:1422-32. [PMID: 22190420 DOI: 10.1002/dneu.22003] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2011] [Revised: 11/29/2011] [Accepted: 12/01/2011] [Indexed: 11/06/2022]
Abstract
The ability of axons to project correctly to the target is essential for the formation of complex neural networks. The intrinsic regulation of this process is still unclear. Here, we show that POU domain motif 3 (Pdm3) is required in ring (R) neurons to control precise axon targeting to the Drosophila ellipsoid body (EB). Pdm3 is expressed in neurons of the central nervous system in larvae and adults and required for the normal development of the EB of the central complex in the adult brain. The normal EB structure is abolished in pdm3 mutants, and this phenotype is rescued by pdm3 expression in R neurons, suggesting that the defect in axonal targeting of R neurons is the major cause in EB malformation in pdm3 mutants. We show that cell fate determination, dendritic arborization, and initial axon projection of R neurons are normal while the axonal targeting to the EB is defective in pdm3 mutants.
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Affiliation(s)
- Chien-Kuo Chen
- Institute of Neuroscience, National Yang-Ming University, Taipei, Taiwan
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25
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Progressive tarsal patterning in the Drosophila by temporally dynamic regulation of transcription factor genes. Dev Biol 2012; 361:450-62. [DOI: 10.1016/j.ydbio.2011.10.031] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2011] [Revised: 10/24/2011] [Accepted: 10/25/2011] [Indexed: 10/15/2022]
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Turchyn N, Chesebro J, Hrycaj S, Couso JP, Popadić A. Evolution of nubbin function in hemimetabolous and holometabolous insect appendages. Dev Biol 2011; 357:83-95. [PMID: 21708143 DOI: 10.1016/j.ydbio.2011.06.014] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2010] [Revised: 06/10/2011] [Accepted: 06/11/2011] [Indexed: 10/18/2022]
Abstract
Insects display a whole spectrum of morphological diversity, which is especially noticeable in the organization of their appendages. A recent study in a hemipteran, Oncopeltus fasciatus (milkweed bug), showed that nubbin (nub) affects antenna morphogenesis, labial patterning, the length of the femoral segment in legs, and the formation of a limbless abdomen. To further determine the role of this gene in the evolution of insect morphology, we analyzed its functions in two additional hemimetabolous species, Acheta domesticus (house cricket) and Periplaneta americana (cockroach), and re-examined its role in Drosophila melanogaster (fruit fly). While both Acheta and Periplaneta nub-RNAi first nymphs develop crooked antennae, no visible changes are observed in the morphologies of their mouthparts and abdomen. Instead, the main effect is seen in legs. The joint between the tibia and first tarsomere (Ta-1) is lost in Acheta, which in turn, causes a fusion of these two segments and creates a chimeric nub-RNAi tibia-tarsus that retains a tibial identity in its proximal half and acquires a Ta-1 identity in its distal half. Similarly, our re-analysis of nub function in Drosophila reveals that legs lack all true joints and the fly tibia also exhibits a fused tibia and tarsus. Finally, we observe a similar phenotype in Periplaneta except that it encompasses different joints (coxa-trochanter and femur-tibia), and in this species we also show that nub expression in the legs is regulated by Notch signaling, as had previously been reported in flies and spiders. Overall, we propose that nub acts downstream of Notch on the distal part of insect leg segments to promote their development and growth, which in turn is required for joint formation. Our data represent the first functional evidence defining a role for nub in leg segmentation and highlight the varying degrees of its involvement in this process across insects.
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Affiliation(s)
- Nataliya Turchyn
- Department of Biological Sciences, Wayne State University, Detroit, MI 48202, USA
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27
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Takashima S, Younossi-Hartenstein A, Ortiz PA, Hartenstein V. A novel tissue in an established model system: the Drosophila pupal midgut. Dev Genes Evol 2011; 221:69-81. [PMID: 21556856 PMCID: PMC3950650 DOI: 10.1007/s00427-011-0360-x] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2011] [Accepted: 03/23/2011] [Indexed: 01/20/2023]
Abstract
The Drosophila larval and adult midguts are derived from two populations of endodermal progenitors that separate from each other in the early embryo. As larval midgut cells differentiate into an epithelial layer, adult midgut progenitors (AMPs) remain as small clusters of proliferating, undifferentiated cells attached to the basal surface of the larval gut epithelium. During the first few hours of metamorphosis, AMPs merge into a continuous epithelial tube that overgrows the larval layer and differentiates into the adult midgut; at the same time, the larval midgut degenerates. As shown in this paper, there is a second, transient pupal midgut that develops from the AMPs at the beginning of metamorphosis and that intercalates between the adult and larval midgut epithelia. Cells of the transient pupal midgut form a multilayered tube that exhibits signs of differentiation, in the form of septate junctions and rudimentary apical microvilli. Some cells of the pupal midgut develop as endocrine cells. The pupal midgut remains closely attached to the degenerating larval midgut cells. Along with these cells, pupal midgut cells are sequestered into the lumen where they form the compact "yellow body." The formation of a pupal midgut has been reported from several other species and may represent a general feature of intestinal metamorphosis in insects.
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Affiliation(s)
- Shigeo Takashima
- Department of Molecular Cell and Developmental Biology, University of California Los Angeles, Los Angeles, CA 90095, USA
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28
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Bhat KM, Gaziova I, Katipalla S. Neuralized mediates asymmetric division of neural precursors by two distinct and sequential events: promoting asymmetric localization of Numb and enhancing activation of Notch-signaling. Dev Biol 2010; 351:186-98. [PMID: 21147089 DOI: 10.1016/j.ydbio.2010.12.008] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2010] [Revised: 11/22/2010] [Accepted: 12/02/2010] [Indexed: 11/19/2022]
Abstract
In the CNS, the evolutionarily conserved Notch pathway regulates asymmetric cell fate specification to daughters of ganglion mother cells (GMCs). The E3 Ubiquitin ligase protein Neuralized (Neur) is thought to activate Notch-signaling by the endocytosis of Delta and the Delta-bound extracellular domain of Notch. The intracellular Notch then initiates Notch-signaling. Numb blocks N-signaling in one of the two daughters of a GMC, allowing that cell to adopt a different identity. Numb is asymmetrically localized in a GMC and is segregated to only one of the two daughter cells. In the typical GMC-1→RP2/sib lineage, we found that loss of Neur activity causes symmetric division of GMC-1 into two RP2s. We further found that Neur asymmetrically localizes in a late GMC-1 to the Numb domain and Neur mediates asymmetric division via two distinct, sequential mechanisms: by promoting the asymmetric localization of Numb in a GMC-1 via down-regulation of the transcription factor Pdm1, followed by enhancing the Notch-signaling via trans-potentiation of Notch in a cell committed to become a sib. In neur mutants the GMC-1 identity is not altered but Numb is non-asymmetrically localized due to an up-regulation of Pdm1. Thus, both its daughters inherit Numb, which prevents Notch from specifying a sib identity. Neur also enhances Notch since in neur; numb double mutants, both sibling cells often adopt a mixed fate as opposed to an RP2 fate observed in Notch; numb double mutants. Furthermore, over-expression of Neur can induce both cells to adopt a sib fate similar to gain of function Notch. Our results tie Numb and Notch-signaling through a single player, Neur, thus giving us a more complete picture of the events surrounding asymmetric division of precursor cells. We also show that Neur and Numb are interdependent for their asymmetric-localizations.
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Affiliation(s)
- Krishna Moorthi Bhat
- Department of Neuroscience and Cell Biology, University of Texas Medical Branch School of Medicine, Galveston, TX 77555, USA
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Lee MC, Toh LL, Yaw LP, Luo Y. Drosophila octamer elements and Pdm-1 dictate the coordinated transcription of core histone genes. J Biol Chem 2010; 285:9041-53. [PMID: 20097756 DOI: 10.1074/jbc.m109.075358] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
We reveal a set of divergent octamer elements in Drosophila melanogaster (dm) core histone gene promoters. These elements recruit transcription factor POU-domain protein in D. melanogaster 1 (Pdm-1), which along with co-activator dmOct-1 coactivator in S-phase (dmOCA-S), activates transcription from at least the Drosophila histone 2B (dmH2B) and 4 (dmH4) promoters in a fashion similar to the transcription of mammalian histone 2B (H2B) gene activated by octamer binding transcription factor 1 (Oct-1) and Oct-1 coactivator in S-phase (OCA-S). The expression of core histone genes in both kingdoms is coordinated; however, although the expression of mammalian histone genes involves subtype-specific transcription factors and/or co-activator(s), the expression of Drosophila core histone genes is regulated by a common module (Pdm-1/dmOCA-S) in a directly coordinated manner. Finally, dmOCA-S is recruited to the Drosophila histone locus bodies in the S-phase, marking S-phase-specific transcription activation of core histone genes.
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Affiliation(s)
- Mei-Chin Lee
- Institute of Molecular and Cell Biology, 61 Biopolis Drive, Proteos, Singapore
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Mace DL, Varnado N, Zhang W, Frise E, Ohler U. Extraction and comparison of gene expression patterns from 2D RNA in situ hybridization images. ACTA ACUST UNITED AC 2009; 26:761-9. [PMID: 19942587 DOI: 10.1093/bioinformatics/btp658] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
MOTIVATION Recent advancements in high-throughput imaging have created new large datasets with tens of thousands of gene expression images. Methods for capturing these spatial and/or temporal expression patterns include in situ hybridization or fluorescent reporter constructs or tags, and results are still frequently assessed by subjective qualitative comparisons. In order to deal with available large datasets, fully automated analysis methods must be developed to properly normalize and model spatial expression patterns. RESULTS We have developed image segmentation and registration methods to identify and extract spatial gene expression patterns from RNA in situ hybridization experiments of Drosophila embryos. These methods allow us to normalize and extract expression information for 78,621 images from 3724 genes across six time stages. The similarity between gene expression patterns is computed using four scoring metrics: mean squared error, Haar wavelet distance, mutual information and spatial mutual information (SMI). We additionally propose a strategy to calculate the significance of the similarity between two expression images, by generating surrogate datasets with similar spatial expression patterns using a Monte Carlo swap sampler. On data from an early development time stage, we show that SMI provides the most biologically relevant metric of comparison, and that our significance testing generalizes metrics to achieve similar performance. We exemplify the application of spatial metrics on the well-known Drosophila segmentation network. AVAILABILITY A Java webstart application to register and compare patterns, as well as all source code, are available from: http://tools.genome.duke.edu/generegulation/image_analysis/insitu CONTACT uwe.ohler@duke.edu SUPPLEMENTARY INFORMATION Supplementary data are available at Bioinformatics online.
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Affiliation(s)
- Daniel L Mace
- Computational Biology and Bioinformatics Graduate Program, Duke University, Durham, NC 27708, USA
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JAK/STAT signaling coordinates stem cell proliferation and multilineage differentiation in the Drosophila intestinal stem cell lineage. Dev Biol 2009; 338:28-37. [PMID: 19896937 DOI: 10.1016/j.ydbio.2009.10.045] [Citation(s) in RCA: 176] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2009] [Revised: 10/03/2009] [Accepted: 10/31/2009] [Indexed: 12/13/2022]
Abstract
Adult stem cells are the most primitive cells of a lineage and are distinguished by the properties of self-renewal and multipotency. Coordinated control of stem cell proliferation and multilineage differentiation is essential to ensure a steady output of differentiated daughter cells necessary to maintain tissue homeostasis. However, little is known about the signals that coordinate stem cell proliferation and daughter cell differentiation. Here we investigate the role of the conserved JAK/STAT signaling pathway in the Drosophila intestinal stem cell (ISC) lineage. We show first, that JAK/STAT signaling is normally active in both ISCs and their newly formed daughters, but not in terminally differentiated enteroendocrine (ee) cells or enterocyte (EC) cells. Second, analysis of ISC lineages shows that JAK/STAT signaling is necessary but not sufficient for daughter cell differentiation, indicating that competence to undergo multilineage differentiation depends upon JAK/STAT. Finally, our analysis reveals JAK/STAT signaling to be a potent regulator of ISC proliferation, but not ISC self-renewal. On the basis of these findings, we suggest a model in which JAK/STAT signaling coordinates the processes of stem cell proliferation with the competence of daughter cells to undergo multilineage differentiation, ensuring a robust cellular output in the lineage.
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Lee WC, Beebe K, Sudmeier L, Micchelli CA. Adenomatous polyposis coli regulates Drosophila intestinal stem cell proliferation. Development 2009; 136:2255-64. [PMID: 19502486 DOI: 10.1242/dev.035196] [Citation(s) in RCA: 141] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Adult stem cells define a cellular reserve with the unique capacity to replenish differentiated cells of a tissue throughout an organism's lifetime. Previous analysis has demonstrated that the adult Drosophila midgut is maintained by a population of multipotent intestinal stem cells (ISCs) that resides in epithelial niches. Adenomatous polyposis coli (Apc), a tumor suppressor gene conserved in both invertebrates and vertebrates, is known to play a role in multiple developmental processes in Drosophila. Here, we examine the consequences of eliminating Apc function on adult midgut homeostasis. Our analysis shows that loss of Apc results in the disruption of midgut homeostasis and is associated with hyperplasia and multilayering of the midgut epithelium. A mosaic analysis of marked ISC cell lineages demonstrates that Apc is required specifically in ISCs to regulate proliferation, but is not required for ISC self-renewal or the specification of cell fate within the lineage. Cell autonomous activation of Wnt signaling in the ISC lineage phenocopied Apc loss and Apc mutants were suppressed in an allele-specific manner by abrogating Wnt signaling, suggesting that the effects of Apc are mediated in part by the Wnt pathway. Together, these data underscore the essential requirement of Apc in exerting regulatory control over stem cell activity, as well as the consequences that disrupting this regulation can have on tissue homeostasis.
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Affiliation(s)
- Wen-Chih Lee
- Department of Developmental Biology, Washington University School of Medicine, 660 South Euclid Avenue, St Louis, MO 63110, USA
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33
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Benítez E, Bray SJ, Rodriguez I, Guerrero I. Lines is required for normal operation of Wingless, Hedgehog and Notch pathways during wing development. Development 2009; 136:1211-21. [PMID: 19270177 DOI: 10.1242/dev.021428] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The regulatory Lines/Drumstick/Bowl gene network is implicated in the integration of patterning information at several stages during development. Here, we show that during Drosophila wing development, Lines prevents Bowl accumulation in the wing primordium, confining its expression to the peripodial epithelium. In cells that lack lines or over-expressing Drumstick, Bowl stabilization is responsible for alterations such as dramatic overgrowths and cell identity changes in the proximodistal patterning owing to aberrant responses to signaling pathways. The complex phenotypes are explained by Bowl repressing the Wingless pathway, the earliest effect seen. In addition, Bowl sequesters the general co-repressor Groucho from repressor complexes functioning in the Notch pathway and in Hedgehog expression, leading to ectopic activity of their targets. Supporting this model, elimination of the Groucho interaction domain in Bowl prevents the activation of the Notch and Hedgehog pathways, although not the repression of the Wingless pathway. Similarly, the effects of ectopic Bowl are partially rescued by co-expression of either Hairless or Master of thickveins, co-repressors that act with Groucho in the Notch and Hedgehog pathways, respectively. We conclude that by preventing Bowl accumulation in the wing, primordial Lines permits the correct balance of nuclear co-repressors that control the activity of the Wingless, Notch and Hedgehog pathways.
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Affiliation(s)
- Elvira Benítez
- Universidad Autónoma de Madrid, Cantoblanco, E-28049 Madrid, Spain
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34
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Huh JY, Jeon SH, Kim SH. The CNS midline cells and Egfr signaling genes are required for establishment of the RP2 motoneuron lineage in the Drosophila central nervous system. Biochem Biophys Res Commun 2009; 380:729-35. [PMID: 19250628 DOI: 10.1016/j.bbrc.2009.01.104] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2009] [Accepted: 01/16/2009] [Indexed: 11/24/2022]
Abstract
It is well established that CNS midline cells are essential for the identity determination, division, and differentiation of neurons and glia in the Drosophila CNS. However, it is not clear whether CNS midline cells control the establishment and differentiation of the well-known RP2 motoneuron lineage. The present study showed by using several RP2 lineage markers that CNS midline cells and Egfr signaling genes are required for identity determination and formation of precursors of the RP2 motoneurons. Overexpression and ectopic expression of sim and components of the EGFR signaling pathway in the ventral neuroectoderm induced the formation of extra RP2s and their sibling cells by activating EGFR signaling. We demonstrated that CNS midline cells and Egfr signaling genes play essential roles in the establishment of the RP2 motoneuron lineage.
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Affiliation(s)
- Jung Yun Huh
- Department of Chemistry, Konkuk University, 1 Hwayang-dong Gwangjin-gu, Seoul 143-701, Republic of Korea
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35
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Gaziova I, Bhat KM. Ancestry-independent fate specification and plasticity in the developmental timing of a typical Drosophila neuronal lineage. Development 2008; 136:263-74. [PMID: 19088087 DOI: 10.1242/dev.027854] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
In the Drosophila CNS, combinatorial, interdependent, sequential genetic programs in neuroectodermal (NE) cells, prior to the formation of neuroblasts (NBs), determine the initial identity of NBs. Temporal factors are then sequentially expressed to change the temporal identity. It is unclear at what levels this positional and temporal information integrates to determine progeny cell identity. One idea is that this is a top-down linear process: the identity of a NB determines the identity of its daughter, the ganglion mother cell (GMC), the asymmetric division of the GMC and the fate specification of daughter cells of the GMC. Our results with midline (mid), which encodes a T-box protein, in a typical lineage, NB4-2-->GMC-1-->RP2/sib, suggest that at least part of the process operates in GMCs. That is, a GMC or a neuronal identity need not be determined at the NB or NE level. This is demonstrated by showing that Mid is expressed in a row 5 GMC (M-GMC), but not in its parent NB or NE cell. In mid mutants, M-GMC changes into GMC-1 and generates an RP2 and a sib without affecting the expression of key genes at the NE/NB levels. Expression of Mid in the M-GMC in mid mutants rescues the fate change, indicating that Mid specifies neurons at the GMC level. Moreover, we found a significant plasticity in the temporal window in which a neuronal lineage can develop. Although the extra GMC-1 in mid mutants is born approximately 2 hours later than the bona fide GMC-1, it follows the same developmental pattern as the bona fide GMC-1. Thus, a GMC identity can be independent of parental identity and GMC formation and elaboration need not be strictly time-bound.
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Affiliation(s)
- Ivana Gaziova
- Department of Neuroscience and Cell Biology, University of Texas Medical Branch School of Medicine, Galveston, TX 77555, USA
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36
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Hrycaj S, Mihajlovic M, Mahfooz N, Couso JP, Popadić A. RNAi analysis of nubbin embryonic functions in a hemimetabolous insect, Oncopeltus fasciatus. Evol Dev 2008; 10:705-16. [DOI: 10.1111/j.1525-142x.2008.00284.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
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Tran KD, Doe CQ. Pdm and Castor close successive temporal identity windows in the NB3-1 lineage. Development 2008; 135:3491-9. [PMID: 18832394 DOI: 10.1242/dev.024349] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Neurogenesis in Drosophila and mammals requires the precise integration of spatial and temporal cues. In Drosophila, embryonic neural progenitors (neuroblasts) sequentially express the transcription factors Hunchback, Kruppel, Pdm1/Pdm2 (Pdm) and Castor as they generate a stereotyped sequence of neuronal and glial progeny. Hunchback and Kruppel specify early temporal identity in two posterior neuroblast lineages (NB7-1 and NB7-3), whereas Pdm and Castor specify late neuronal identity in the NB7-1 lineage. Because Pdm and Castor have only been assayed in one lineage, it is unknown whether their function is restricted to neuronal identity in the NB7-1 lineage, or whether they function more broadly as late temporal identity genes in all neuroblast lineages. Here, we identify neuronal birth-order and molecular markers within the NB3-1 cell lineage, and then use this lineage to assay Pdm and Castor function. We show that Hunchback and Kruppel specify first and second temporal identities, respectively. Surprisingly, Pdm does not specify the third temporal identity, but instead acts as a timing factor to close the second temporal identity window. Similarly, Castor closes the third temporal identity window. We conclude that Hunchback and Kruppel specify the first and second temporal identities, an unknown factor specifies the third temporal identity, and Pdm and Castor are timing factors that close the second and third temporal identity windows in the NB3-1 lineage. Our results provide a new neuroblast lineage for investigating temporal identity and reveal the importance of Pdm and Cas as timing factors that close temporal identity windows.
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Affiliation(s)
- Khoa D Tran
- Institute of Neuroscience, Institute of Molecular Biology, Howard Hughes Medical Institute, University of Oregon, Eugene, OR 97403, USA
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38
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Beckervordersandforth RM, Rickert C, Altenhein B, Technau GM. Subtypes of glial cells in the Drosophila embryonic ventral nerve cord as related to lineage and gene expression. Mech Dev 2008; 125:542-57. [PMID: 18296030 DOI: 10.1016/j.mod.2007.12.004] [Citation(s) in RCA: 84] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2007] [Revised: 12/20/2007] [Accepted: 12/21/2007] [Indexed: 10/22/2022]
Abstract
In the Drosophila embryonic CNS several subtypes of glial cells develop, which arrange themselves at characteristic positions and presumably fulfil specific functions. The mechanisms leading to the specification and differentiation of glial subtypes are largely unknown. By DiI labelling in glia-specific Gal4 lines we have clarified the lineages of the lateral glia in the embryonic ventral nerve cord and linked each glial cell to a specific stem cell. For the lineage of the longitudinal glioblast we show that it consists of 9 cells, which acquire at least four different identities. A large collection of molecular markers (many of them representing transcription factors and potential Gcm target genes) reveals that individual glial cells express specific combinations of markers. However, cluster analysis uncovers similar combinatorial codes for cells within, and significant differences between the categories of surface-associated, cortex-associated, and longitudinal glia. Glial cells derived from the same stem cell may be homogeneous (though not identical; stem cells NB1-1, NB5-6, NB6-4, LGB) or heterogeneous (NB7-4, NB1-3) with regard to gene expression. In addition to providing a powerful tool to analyse the fate of individual glial cells in different genetic backgrounds, each of these marker genes represents a candidate factor involved in glial specification or differentiation. We demonstrate this by the analysis of a castor loss of function mutation, which affects the number and migration of specific glial cells.
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39
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von Hilchen CM, Beckervordersandforth RM, Rickert C, Technau GM, Altenhein B. Identity, origin, and migration of peripheral glial cells in the Drosophila embryo. Mech Dev 2007; 125:337-52. [PMID: 18077143 DOI: 10.1016/j.mod.2007.10.010] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2007] [Revised: 10/19/2007] [Accepted: 10/24/2007] [Indexed: 10/22/2022]
Abstract
Glial cells are crucial for the proper development and function of the nervous system. In the Drosophila embryo, the glial cells of the peripheral nervous system are generated both by central neuroblasts and sensory organ precursors. Most peripheral glial cells need to migrate along axonal projections of motor and sensory neurons to reach their final positions in the periphery. Here we studied the spatial and temporal pattern, the identity, the migration, and the origin of all peripheral glial cells in the truncal segments of wildtype embryos. The establishment of individual identities among these cells is reflected by the expression of a combinatorial code of molecular markers. This allows the identification of individual cells in various genetic backgrounds. Furthermore, mutant analysis of two of these marker genes, spalt major and castor, reveal their implication in peripheral glial development. Using confocal 4D microscopy to monitor and follow peripheral glia migration in living embryos, we show that the positioning of most of these cells is predetermined with minor variations, and that the order in which cells migrate into the periphery is almost fixed. By studying their lineages, we uncovered the origin of each of the peripheral glial cells and linked them to identified central and peripheral neural stem cells.
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40
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Junell A, Uvell H, Pick L, Engström Y. Isolation of regulators of Drosophila immune defense genes by a double interaction screen in yeast. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2007; 37:202-12. [PMID: 17296495 DOI: 10.1016/j.ibmb.2006.10.008] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/20/2006] [Revised: 10/19/2006] [Accepted: 10/26/2006] [Indexed: 05/13/2023]
Abstract
Innate immunity is a universal and ancient defense system in metazoans against microorganisms. Antimicrobial peptides, which are synthesized both in insects and humans, constitute an endogenous, gene-encoded defense arsenal. In Drosophila, antimicrobial peptides, such as the potent cecropins, are expressed both constitutively in barrier epithelia, as well as systemically in response to infection. Rel/NF-kappaB proteins are well-known regulators of antimicrobial peptide genes, but very few Rel/NF-kappaB co-factors and/or tissue-specific regulators have been identified. We performed a double interaction screen in yeast to isolate Drosophila cDNAs coding for direct regulators, as well as Dif co-regulators, of the CecropinA1 gene. Three classes of positive cDNA clones corresponding to 15 Drosophila genes were isolated and further characterized. One of the Dif-independent cDNAs encoded the Rel/NF-kappaB protein Relish; a well-known activator of antimicrobial peptide genes in Drosophila, demonstrating the applicability of this type of screen for isolating regulators of immune defense. Most interestingly, three transcription factors belonging to the POU domain class of homeodomain proteins, Pdm1, Pdm2 and Dfr/Vvl were isolated as Dif-interacting partners, and subsequently verified as regulators of CecA1 expression in Drosophila cells. The importance of POU proteins in development and differentiation in Drosophila and mammals is well documented, but their role in regulation of Drosophila immune defense genes is a new and essential finding.
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Affiliation(s)
- Anna Junell
- Department of Molecular Biology and Functional Genomics, Stockholm University, S-109 61 Stockholm, Sweden
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41
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Gaziova I, Bhat KM. Generating asymmetry: with and without self-renewal. PROGRESS IN MOLECULAR AND SUBCELLULAR BIOLOGY 2007; 45:143-78. [PMID: 17585500 DOI: 10.1007/978-3-540-69161-7_7] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
At some point during the history of organismal evolution, unicellular, unipotent and mitotically active cells acquired an ability to undergo a special type of cell division called asymmetric division. By this special type of cell division, these cells could divide to generate two different progeny or to self-renew and at the same time generate a progeny that is committed to become a cell different from the mother cell. This type of cell division, which forms the basis for the functioning of totipotent or multipotent stem cells, underlies the fundamental basis for the developmental evolution of organisms. It is not clear if the asymmetric division without self-renewal preceded the asymmetric division with self-renewal. It is reasonable to assume that the asymmetric division without self-renewal preceded the asymmetric division with self-renewal. In this review we explore the genetic regulation of these two types of asymmetric divisions using the Drosophila central nervous system (CNS) as a model system. The results from recent studies argue that for cells to undergo a self-renewing asymmetric division, certain "stem cell" proteins must be maintained or up-regulated, while genes encoding proteins responsible for differentiation must be repressed or down-regulated. As long as a balance between these two classes of proteins is maintained via asymmetric segregation and activation/repression, the progeny that receives stem cell proteins/maintains stem cell competence will have the potential to undergo self-renewing asymmetric division. The other progeny will commit to differentiate. In non-self-renewing asymmetric division, down-regulation of stem cell proteins/competence combined with asymmetric segregation of cell identity specifying factors (either cell-autonomous or a combination of cell autonomous and non-cell autonomous signals) cause the two progeny to assume different differentiated identities. Identification of mutations that confer a stem cell type of division to nonstem cell precursors, or mutations that eliminate asymmetric division, has led the way in elucidating the molecular basis for these divisions. Given that there is a considerable degree of conservation of genes and their function, these studies should provide clear insight into how the self-renewing asymmetric division of stem cells in neural and other lineages is regulated not only in Drosophila but also in vertebrates including humans.
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Affiliation(s)
- Ivana Gaziova
- Department of Neuroscience and Cell Biology, University of Texas Medical Branch School of Medicine, Galveston, Texas 77555, USA
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42
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Grosskortenhaus R, Robinson KJ, Doe CQ. Pdm and Castor specify late-born motor neuron identity in the NB7-1 lineage. Genes Dev 2006; 20:2618-27. [PMID: 16980589 PMCID: PMC1578683 DOI: 10.1101/gad.1445306] [Citation(s) in RCA: 87] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Embryonic development requires generating cell types at the right place (spatial patterning) and the right time (temporal patterning). Drosophila neuroblasts undergo stem cell-like divisions to generate an ordered sequence of neuronal progeny, making them an attractive system to study temporal patterning. Embryonic neuroblasts sequentially express Hunchback, Krüppel, Pdm1/Pdm2 (Pdm), and Castor (Cas) transcription factors. Hunchback and Krüppel specify early-born temporal identity, but the role of Pdm and Cas in specifying temporal identity has never been addressed. Here we show that Pdm and Cas regulate late-born motor neuron identity within the NB7-1 lineage: Pdm specifies fourth-born U4 motor neuron identity, while Pdm/Cas together specify fifth-born U5 motor neuron identity. We conclude that Pdm and Cas specify late-born neuronal identity; that Pdm and Cas act combinatorially to specify a temporal identity distinct from either protein alone, and that Cas repression of pdm expression regulates the generation of neuronal diversity.
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Affiliation(s)
- Ruth Grosskortenhaus
- Institute of Neuroscience, Howard Hughes Medical Institute, University of Oregon, Eugene, 97403, USA
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43
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Abstract
Previous studies have shown that the gene nubbin (nub) exhibits large differences in expression patterns between major groups of arthropods. This led us to hypothesize that nub may have evolved roles that are unique to particular arthropod lineages. However, in insects, nub has been studied only in Drosophila. To further explore its role in insects in general, we analyzed nub expression patterns in three hemimetabolous insect groups: zygentomans (Thermobia domestica, firebrat), dyctiopterans (Periplaneta americana, cockroach), and hemipterans (Oncopeltus fasciatus, milkweed bug). We discovered three major findings. First, observed nub patterns in the ventral central nervous system ectoderm represent a synapomorphy (shared derived feature) that is not present in other arthropods. Furthermore, each of the analyzed insects exhibits a species-specific nub expression in the central nervous system. Second, recruitment of nub for a role in leg segmentation occurred early during insect evolution. Subsequently, in some insect lineages (cockroaches and flies), this original role was expanded to include joints between all the leg segments. Third, the nub expression in the head region shows a coordinated change in association with particular mouthpart morphology. This suggests that nub has also gained an important role in the morphological diversification of insect mouthparts. Overall, the obtained data reveal an extraordinary dynamic and diverse pattern of nub evolution that has not been observed previously for other developmental genes.
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Affiliation(s)
- Hua Li
- Department of Biological Sciences, Wayne State University, Detroit, MI 48202, USA
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44
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Bhat KM, Apsel N. Upregulation of Mitimere and Nubbin acts through cyclin E to confer self-renewing asymmetric division potential to neural precursor cells. Development 2004; 131:1123-34. [PMID: 14973280 DOI: 10.1242/dev.01014] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
In the Drosophila CNS, neuroblasts undergo self-renewing asymmetric divisions, whereas their progeny, ganglion mother cells (GMCs), divide asymmetrically to generate terminal postmitotic neurons. It is not known whether GMCs have the potential to undergo self-renewing asymmetric divisions. It is also not known how precursor cells undergo self-renewing asymmetric divisions. Here, we report that maintaining high levels of Mitimere or Nubbin, two POU proteins, in a GMC causes it to undergo self-renewing asymmetric divisions. These asymmetric divisions are due to upregulation of Cyclin E in late GMC and its unequal distribution between two daughter cells. GMCs in an embryo overexpressing Cyclin E, or in an embryo mutant for archipelago, also undergo self-renewing asymmetric divisions. Although the GMC self-renewal is independent of inscuteable and numb, the fate of the differentiating daughter is inscuteable and numb-dependent. Our results reveal that regulation of Cyclin E levels, and asymmetric distribution of Cyclin E and other determinants, confer self-renewing asymmetric division potential to precursor cells, and thus define a pathway that regulates such divisions. These results add to our understanding of maintenance and loss of pluripotential stem cell identity.
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Affiliation(s)
- Krishna Moorthi Bhat
- Department of Cell Biology, Emory University School of Medicine, Atlanta, GA 30322, USA.
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45
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Carney GE, Robertson A, Davis MB, Bender M. Creation of EcR isoform-specific mutations in Drosophila melanogaster via local P element transposition, imprecise P element excision, and male recombination. Mol Genet Genomics 2004; 271:282-90. [PMID: 14747942 DOI: 10.1007/s00438-004-0976-x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2003] [Accepted: 12/23/2003] [Indexed: 10/26/2022]
Abstract
Collections of single P transposable-element insertion strains that currently inactivate more than 25% of essential Drosophila genes have proven to be a valuable tool for genome research in Drosophila melanogaster. For genes unrepresented in these collections, strategies including local P element transposition and transposase-induced imprecise excision can be used to inactivate or delete the gene of interest. Here we report our use of local P element transposition followed by imprecise P element excision and transposase-induced male recombination to generate two deficiencies specific for the EcR-A isoform of the ecdysone receptor ( EcR) gene, and four larger deficiencies likely to affect multiple EcR functions. We also report here the determination of sequences flanking six EcR-B deficiencies generated in a previous imprecise excision screen. EcR-A encodes one of a family of three related nuclear receptor proteins that, together with the heterodimer partner USP, mediate ecdysone signaling during Drosophila development. Our results delineate sequences required in vivo for EcR-A function, as well as identifying EcR-A intron 1 sequences that are not essential for EcR function.
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Affiliation(s)
- G E Carney
- Department of Genetics, University of Georgia, Athens, GA 30602, USA
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46
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McDonald JA, Fujioka M, Odden JP, Jaynes JB, Doe CQ. Specification of motoneuron fate inDrosophila: Integration of positive and negative transcription factor inputs by a minimaleve enhancer. ACTA ACUST UNITED AC 2003; 57:193-203. [PMID: 14556285 DOI: 10.1002/neu.10264] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
We are interested in the mechanisms that generate neuronal diversity within the Drosophila central nervous system (CNS), and in particular in the development of a single identified motoneuron called RP2. Expression of the homeodomain transcription factor Even-skipped (Eve) is required for RP2 to establish proper connectivity with its muscle target. Here we investigate the mechanisms by which eve is specifically expressed within the RP2 motoneuron lineage. Within the NB4-2 lineage, expression of eve first occurs in the precursor of RP2, called GMC4-2a. We identify a small 500 base pair eve enhancer that mediates eve expression in GMC4-2a. We show that four different transcription factors (Prospero, Huckebein, Fushi tarazu, and Pdm1) are all expressed in GMC4-2a, and are required to activate eve via this minimal enhancer, and that one transcription factor (Klumpfuss) represses eve expression via this element. All four positively acting transcription factors act independently, regulating eve but not each other. Thus, the eve enhancer integrates multiple positive and negative transcription factor inputs to restrict eve expression to a single precursor cell (GMC4-2a) and its RP2 motoneuron progeny.
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Affiliation(s)
- Jocelyn A McDonald
- Institutes of Neuroscience and Molecular Biology, HHMI, 1254 University of Oregon, Eugene, Oregon 97403, USA.
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47
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Urbach R, Technau GM. Molecular markers for identified neuroblasts in the developing brain of Drosophila. Development 2003; 130:3621-37. [PMID: 12835380 DOI: 10.1242/dev.00533] [Citation(s) in RCA: 197] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The Drosophila brain develops from the procephalic neurogenic region of the ectoderm. About 100 neural precursor cells (neuroblasts) delaminate from this region on either side in a reproducible spatiotemporal pattern. We provide neuroblast maps from different stages of the early embryo (stages 9, 10 and 11, when the entire population of neuroblasts has formed), in which about 40 molecular markers representing the expression patterns of 34 different genes are linked to individual neuroblasts. In particular, we present a detailed description of the spatiotemporal patterns of expression in the procephalic neuroectoderm and in the neuroblast layer of the gap genes empty spiracles, hunchback, huckebein, sloppy paired 1 and tailless; the homeotic gene labial; the early eye genes dachshund, eyeless and twin of eyeless; and several other marker genes (including castor, pdm1, fasciclin 2, klumpfuss, ladybird, runt and unplugged). We show that based on the combination of genes expressed, each brain neuroblast acquires a unique identity, and that it is possible to follow the fate of individual neuroblasts through early neurogenesis. Furthermore, despite the highly derived patterns of expression in the procephalic segments, the co-expression of specific molecular markers discloses the existence of serially homologous neuroblasts in neuromeres of the ventral nerve cord and the brain. Taking into consideration that all brain neuroblasts are now assigned to particular neuromeres and individually identified by their unique gene expression, and that the genes found to be expressed are likely candidates for controlling the development of the respective neuroblasts, our data provide a basic framework for studying the mechanisms leading to pattern and cell diversity in the Drosophila brain, and for addressing those mechanisms that make the brain different from the truncal CNS.
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Affiliation(s)
- Rolf Urbach
- Institut für Genetik, Universität Mainz, D-55099 Mainz, Germany
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Carney GE, Taylor BJ. Logjam encodes a predicted EMP24/GP25 protein that is required for Drosophila oviposition behavior. Genetics 2003; 164:173-86. [PMID: 12750330 PMCID: PMC1462565 DOI: 10.1093/genetics/164.1.173] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
A newly characterized Drosophila melanogaster gene, logjam (loj), functions in female reproduction by modulating oviposition behavior. The locus encodes at least six overlapping transcripts with unique 5' ends. P-element mutants that express very low levels of loj transcripts are unable to oviposit mature eggs. This phenotype can be rescued by the introduction of a transgene expressing the most abundant loj transcript. As for many genes that specify behavioral outputs, loj is present in the adult central nervous system (CNS). Interestingly, it is also observed in vitellogenic egg chambers, suggesting that there may be multiple functions for this gene in egg-laying behavior. loj encodes a predicted protein with homology to the EMP24/GP25 transmembrane components of cytoplasmic vesicles and likely functions in intracellular trafficking.
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Affiliation(s)
- Ginger E Carney
- Department of Zoology, Oregon State University, Corvallis, Oregon 97331-2914, USA.
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Butler MJ, Jacobsen TL, Cain DM, Jarman MG, Hubank M, Whittle JRS, Phillips R, Simcox A. Discovery of genes with highly restricted expression patterns in the Drosophila wing disc using DNA oligonucleotide microarrays. Development 2003; 130:659-70. [PMID: 12505997 DOI: 10.1242/dev.00293] [Citation(s) in RCA: 93] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
The Drosophila wing disc is divided along the proximal-distal axis into regions giving rise to the body wall (proximal), wing hinge (central) and wing blade (distal). We applied DNA microarray analysis to discover genes with potential roles in the development of these regions. We identified a set of 94 transcripts enriched (two fold or greater) in the body wall and 56 transcripts enriched in the wing/hinge region. Transcripts that are known to have highly restricted expression patterns, such as pannier, twist and Bar-H1 (body wall) and knot, nubbin and Distal-less (wing/hinge), showed strong differential expression on the arrays. In situ hybridization for 50 previously uncharacterized genes similarly revealed that transcript enrichment identified by the array analysis was consistent with the observed spatial expression. There was a broad spectrum of patterns, in some cases suggesting that the genes could be targets of known signaling pathways. We show that three of these genes respond to wingless signaling. We also discovered genes likely to play specific roles in tracheal and myoblast cell types, as these cells are part of the body wall fragment. In summary, the identification of genes with restricted expression patterns using whole genome profiling suggests that many genes with potential roles in wing disc development remain to be characterized.
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Affiliation(s)
- Miranda J Butler
- School of Biological Sciences, University of Sussex, Falmer, Brighton BN1 9QG, UK
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50
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Song HJ, Billeter JC, Reynaud E, Carlo T, Spana EP, Perrimon N, Goodwin SF, Baker BS, Taylor BJ. The fruitless gene is required for the proper formation of axonal tracts in the embryonic central nervous system of Drosophila. Genetics 2002; 162:1703-24. [PMID: 12524343 PMCID: PMC1462372 DOI: 10.1093/genetics/162.4.1703] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The fruitless (fru) gene in Drosophila melanogaster is a multifunctional gene that has sex-specific functions in the regulation of male sexual behavior and sex-nonspecific functions affecting adult viability and external morphology. While much attention has focused on fru's sex-specific roles, less is known about its sex-nonspecific functions. We have examined fru's sex-nonspecific role in embryonic neural development. fru transcripts from sex-nonspecific promoters are expressed beginning at the earliest stages of neurogenesis, and Fru proteins are present in both neurons and glia. In embryos that lack most or all fru function, FasII- and BP102-positive axons have defasciculation defects and grow along abnormal pathways in the CNS. These defects in axonal projections in fru mutants were rescued by the expression of specific UAS-fru transgenes under the control of a pan-neuronal scabrous-GAL4 driver. Our results suggest that one of fru's sex-nonspecific roles is to regulate the pathfinding ability of axons in the embryonic CNS.
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Affiliation(s)
- Ho-Juhn Song
- Department of Zoology, Oregon State University, Corvallis, Oregon 97331-2914, USA
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