1
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Zhu H, Ludington WB, Spradling AC. Cellular and molecular organization of the Drosophila foregut. Proc Natl Acad Sci U S A 2024; 121:e2318760121. [PMID: 38442150 PMCID: PMC10945768 DOI: 10.1073/pnas.2318760121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2023] [Accepted: 01/23/2024] [Indexed: 03/07/2024] Open
Abstract
The animal foregut is the first tissue to encounter ingested food, bacteria, and viruses. We characterized the adult Drosophila foregut using transcriptomics to better understand how it triages consumed items for digestion or immune response and manages resources. Cell types were assigned and validated using GFP-tagged and Gal4 reporter lines. Foregut-associated neuroendocrine cells play a major integrative role by coordinating gut activity with nutrition, the microbiome, and circadian cycles; some express clock genes. Multiple epithelial cell types comprise the proventriculus, the central foregut organ that secretes the peritrophic matrix (PM) lining the gut. Analyzing cell types synthesizing individual PM layers revealed abundant mucin production close to enterocytes, similar to the mammalian intestinal mucosa. The esophagus and salivary gland express secreted proteins likely to line the esophageal surface, some of which may generate a foregut commensal niche housing specific gut microbiome species. Overall, our results imply that the foregut coordinates dietary sensing, hormonal regulation, and immunity in a manner that has been conserved during animal evolution.
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Affiliation(s)
- Haolong Zhu
- Biosphere Sciences and Engineering, Carnegie Institution for Science, Baltimore, MD21218
- Department of Biology, Johns Hopkins University, Baltimore, MD21218
| | - William B. Ludington
- Biosphere Sciences and Engineering, Carnegie Institution for Science, Baltimore, MD21218
- Department of Biology, Johns Hopkins University, Baltimore, MD21218
| | - Allan C. Spradling
- Biosphere Sciences and Engineering, Carnegie Institution for Science, Baltimore, MD21218
- Department of Biology, Johns Hopkins University, Baltimore, MD21218
- HHMI, Baltimore, MD21218
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2
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Spradling AC. The Ancient Origin and Function of Germline Cysts. Results Probl Cell Differ 2024; 71:3-21. [PMID: 37996670 DOI: 10.1007/978-3-031-37936-9_1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2023]
Abstract
Gamete production in most animal species is initiated within an evolutionarily ancient multicellular germline structure, the germline cyst, whose interconnected premeiotic cells synchronously develop from a single progenitor arising just downstream from a stem cell. Cysts in mice, Drosophila, and many other animals protect developing sperm, while in females, cysts generate nurse cells that guard sister oocytes from transposons (TEs) and help them grow and build a Balbiani body. However, the origin and extreme evolutionary conservation of germline cysts remains a mystery. We suggest that cysts arose in ancestral animals like Hydra and Planaria whose multipotent somatic and germline stem cells (neoblasts) express genes conserved in all animal germ cells and frequently begin differentiation in cysts. A syncytial state is proposed to help multipotent stem cell chromatin transition to an epigenetic state with heterochromatic domains suitable for TE repression and specialized function. Most modern animals now lack neoblasts but have retained stem cells and cysts in their early germlines, which continue to function using this ancient epigenetic strategy.
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Affiliation(s)
- Allan C Spradling
- Carnegie Institution for Science/Howard Hughes Medical Institute, Baltimore, MD, USA.
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3
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Cobbe N, Di Cara F, Spradling AC, Vass S. Margarete Heck (1959-2023): Cell biologist, geneticist, and incandescent social spark. J Cell Biol 2024; 223:e202311145. [PMID: 38060039 PMCID: PMC10702365 DOI: 10.1083/jcb.202311145] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/08/2023] Open
Abstract
Margarete M.S. Heck, professor of cell biology and genetics, University of Edinburgh, died peacefully at home amid her loving family under a blue moon on August 30, 2023, after a long journey with ovarian cancer.
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Affiliation(s)
| | - Francesca Di Cara
- Department of Microbiology and Immunology, Department of Pediatrics, Dalhousie University, Halifax, Canada
| | - Allan C. Spradling
- Carnegie Institution for Science and Howard Hughes Medical Institute, Baltimore, MD, USA
| | - Sharron Vass
- School of Applied Sciences, Edinburgh Napier University, Scotland, UK
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4
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Pang LY, DeLuca S, Zhu H, Urban JM, Spradling AC. Chromatin and gene expression changes during female Drosophila germline stem cell development illuminate the biology of highly potent stem cells. eLife 2023; 12:RP90509. [PMID: 37831064 PMCID: PMC10575629 DOI: 10.7554/elife.90509] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/14/2023] Open
Abstract
Highly potent animal stem cells either self renew or launch complex differentiation programs, using mechanisms that are only partly understood. Drosophila female germline stem cells (GSCs) perpetuate without change over evolutionary time and generate cystoblast daughters that develop into nurse cells and oocytes. Cystoblasts initiate differentiation by generating a transient syncytial state, the germline cyst, and by increasing pericentromeric H3K9me3 modification, actions likely to suppress transposable element activity. Relatively open GSC chromatin is further restricted by Polycomb repression of testis or somatic cell-expressed genes briefly active in early female germ cells. Subsequently, Neijre/CBP and Myc help upregulate growth and reprogram GSC metabolism by altering mitochondrial transmembrane transport, gluconeogenesis, and other processes. In all these respects GSC differentiation resembles development of the totipotent zygote. We propose that the totipotent stem cell state was shaped by the need to resist transposon activity over evolutionary timescales.
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Affiliation(s)
- Liang-Yu Pang
- Howard Hughes Medical Institute, Carnegie Institution for ScienceBaltimoreUnited States
| | - Steven DeLuca
- Howard Hughes Medical Institute, Carnegie Institution for ScienceBaltimoreUnited States
| | - Haolong Zhu
- Howard Hughes Medical Institute, Carnegie Institution for ScienceBaltimoreUnited States
| | - John M Urban
- Howard Hughes Medical Institute, Carnegie Institution for ScienceBaltimoreUnited States
| | - Allan C Spradling
- Howard Hughes Medical Institute, Carnegie Institution for ScienceBaltimoreUnited States
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5
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Dodge R, Jones EW, Zhu H, Obadia B, Martinez DJ, Wang C, Aranda-Díaz A, Aumiller K, Liu Z, Voltolini M, Brodie EL, Huang KC, Carlson JM, Sivak DA, Spradling AC, Ludington WB. A symbiotic physical niche in Drosophila melanogaster regulates stable association of a multi-species gut microbiota. Nat Commun 2023; 14:1557. [PMID: 36944617 PMCID: PMC10030875 DOI: 10.1038/s41467-023-36942-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2022] [Accepted: 02/22/2023] [Indexed: 03/23/2023] Open
Abstract
The gut is continuously invaded by diverse bacteria from the diet and the environment, yet microbiome composition is relatively stable over time for host species ranging from mammals to insects, suggesting host-specific factors may selectively maintain key species of bacteria. To investigate host specificity, we used gnotobiotic Drosophila, microbial pulse-chase protocols, and microscopy to investigate the stability of different strains of bacteria in the fly gut. We show that a host-constructed physical niche in the foregut selectively binds bacteria with strain-level specificity, stabilizing their colonization. Primary colonizers saturate the niche and exclude secondary colonizers of the same strain, but initial colonization by Lactobacillus species physically remodels the niche through production of a glycan-rich secretion to favor secondary colonization by unrelated commensals in the Acetobacter genus. Our results provide a mechanistic framework for understanding the establishment and stability of a multi-species intestinal microbiome.
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Affiliation(s)
- Ren Dodge
- Department of Embryology, Carnegie Institution for Science, Baltimore, MD, 21218, USA
| | - Eric W Jones
- Department of Physics, Simon Fraser University, Burnaby, BC, V5A 1S6, Canada
- Department of Physics, University of California, Santa Barbara, CA, 93106, USA
| | - Haolong Zhu
- Department of Embryology, Carnegie Institution for Science, Baltimore, MD, 21218, USA
- Department of Biology, Johns Hopkins University, Baltimore, MD, 21218, USA
| | - Benjamin Obadia
- Molecular and Cell Biology Department, University of California, Berkeley, CA, 94720, USA
| | - Daniel J Martinez
- Department of Embryology, Carnegie Institution for Science, Baltimore, MD, 21218, USA
| | - Chenhui Wang
- Department of Embryology, Carnegie Institution for Science, Baltimore, MD, 21218, USA
- Howard Hughes Medical Institute, Baltimore, MD, 21218, USA
| | - Andrés Aranda-Díaz
- Department of Bioengineering, Stanford University, Stanford, CA, 94305, USA
| | - Kevin Aumiller
- Department of Embryology, Carnegie Institution for Science, Baltimore, MD, 21218, USA
- Department of Biology, Johns Hopkins University, Baltimore, MD, 21218, USA
| | - Zhexian Liu
- Department of Biology, Johns Hopkins University, Baltimore, MD, 21218, USA
| | - Marco Voltolini
- Lawrence Berkeley National Lab, Berkeley, CA, 94720, USA
- Dipartimento di Scienze della Terra, Università degli Studi di Milano, Milano, Italy
| | - Eoin L Brodie
- Lawrence Berkeley National Lab, Berkeley, CA, 94720, USA
| | - Kerwyn Casey Huang
- Department of Bioengineering, Stanford University, Stanford, CA, 94305, USA
- Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, CA, 94305, USA
- Chan Zuckerberg Biohub, San Francisco, CA, 94158, USA
| | - Jean M Carlson
- Department of Physics, University of California, Santa Barbara, CA, 93106, USA
| | - David A Sivak
- Department of Physics, Simon Fraser University, Burnaby, BC, V5A 1S6, Canada
| | - Allan C Spradling
- Department of Embryology, Carnegie Institution for Science, Baltimore, MD, 21218, USA
- Department of Biology, Johns Hopkins University, Baltimore, MD, 21218, USA
- Howard Hughes Medical Institute, Baltimore, MD, 21218, USA
| | - William B Ludington
- Department of Embryology, Carnegie Institution for Science, Baltimore, MD, 21218, USA.
- Department of Biology, Johns Hopkins University, Baltimore, MD, 21218, USA.
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6
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Spradling AC, Niu W, Yin Q, Pathak M, Maurya B. Conservation of oocyte development in germline cysts from Drosophila to mouse. eLife 2022; 11:83230. [PMID: 36445738 PMCID: PMC9708067 DOI: 10.7554/elife.83230] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2022] [Accepted: 11/17/2022] [Indexed: 11/30/2022] Open
Abstract
Recent studies show that pre-follicular mouse oogenesis takes place in germline cysts, highly conserved groups of oogonial cells connected by intercellular bridges that develop as nurse cells as well as an oocyte. Long studied in Drosophila and insect gametogenesis, female germline cysts acquire cytoskeletal polarity and traffic centrosomes and organelles between nurse cells and the oocyte to form the Balbiani body, a conserved marker of polarity. Mouse oocyte development and nurse cell dumping are supported by dynamic, cell-specific programs of germline gene expression. High levels of perinatal germ cell death in this species primarily result from programmed nurse cell turnover after transfer rather than defective oocyte production. The striking evolutionary conservation of early oogenesis mechanisms between distant animal groups strongly suggests that gametogenesis and early embryonic development in vertebrates and invertebrates share even more in common than currently believed.
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Affiliation(s)
- Allan C Spradling
- Carnegie Institution for Science/Howard Hughes Medical Institute, Baltimore, United States
| | - Wanbao Niu
- Carnegie Institution for Science/Howard Hughes Medical Institute, Baltimore, United States
| | - Qi Yin
- Carnegie Institution for Science/Howard Hughes Medical Institute, Baltimore, United States
| | - Madhulika Pathak
- Carnegie Institution for Science/Howard Hughes Medical Institute, Baltimore, United States
| | - Bhawana Maurya
- Carnegie Institution for Science/Howard Hughes Medical Institute, Baltimore, United States
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7
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Flanagan K, Baradaran-Heravi A, Yin Q, Dao Duc K, Spradling AC, Greenblatt EJ. FMRP-dependent production of large dosage-sensitive proteins is highly conserved. Genetics 2022; 221:6613139. [PMID: 35731217 PMCID: PMC9339308 DOI: 10.1093/genetics/iyac094] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2022] [Accepted: 06/07/2022] [Indexed: 12/01/2022] Open
Abstract
Mutations in FMR1 are the most common heritable cause of autism spectrum disorder. FMR1 encodes an RNA-binding protein, FMRP, which binds to long, autism-relevant transcripts and is essential for normal neuronal and ovarian development. In contrast to the prevailing model that FMRP acts to block translation elongation, we previously found that FMRP activates the translation initiation of large proteins in Drosophila oocytes. We now provide evidence that FMRP-dependent translation is conserved and occurs in the mammalian brain. Our comparisons of the mammalian cortex and Drosophila oocyte ribosome profiling data show that translation of FMRP-bound mRNAs decreases to a similar magnitude in FMRP-deficient tissues from both species. The steady-state levels of several FMRP targets were reduced in the Fmr1 KO mouse cortex, including a ∼50% reduction of Auts2, a gene implicated in an autosomal dominant autism spectrum disorder. To distinguish between effects on elongation and initiation, we used a novel metric to detect the rate-limiting ribosome stalling. We found no evidence that FMRP target protein production is governed by translation elongation rates. FMRP translational activation of large proteins may be critical for normal human development, as more than 20 FMRP targets including Auts2 are dosage sensitive and are associated with neurodevelopmental disorders caused by haploinsufficiency.
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Affiliation(s)
- Keegan Flanagan
- Department of Biochemistry and Molecular Biology, University of British Columbia, 2350 Health Sciences Mall, Vancouver, British Columbia, V6T 1Z3 Canada.,Department of Mathematics, University of British Columbia, 1984 Mathematics Road, Vancouver, British Columbia, BC V6T 1Z2
| | - Alireza Baradaran-Heravi
- Department of Biochemistry and Molecular Biology, University of British Columbia, 2350 Health Sciences Mall, Vancouver, British Columbia, V6T 1Z3 Canada
| | - Qi Yin
- Howard Hughes Medical Institute Research Laboratories, Department of Embryology, Carnegie Institution for Science, 3520 San Martin Dr., Baltimore, Maryland 21218 USA
| | - Khanh Dao Duc
- Department of Mathematics, University of British Columbia, 1984 Mathematics Road, Vancouver, British Columbia, BC V6T 1Z2
| | - Allan C Spradling
- Howard Hughes Medical Institute Research Laboratories, Department of Embryology, Carnegie Institution for Science, 3520 San Martin Dr., Baltimore, Maryland 21218 USA
| | - Ethan J Greenblatt
- Department of Biochemistry and Molecular Biology, University of British Columbia, 2350 Health Sciences Mall, Vancouver, British Columbia, V6T 1Z3 Canada.,Howard Hughes Medical Institute Research Laboratories, Department of Embryology, Carnegie Institution for Science, 3520 San Martin Dr., Baltimore, Maryland 21218 USA
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8
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Wang C, Spradling AC. Drosophila renal stem cells enhance fitness by delayed remodeling of adult Malpighian tubules. Sci Adv 2022; 8:eabn7436. [PMID: 35594355 PMCID: PMC9122315 DOI: 10.1126/sciadv.abn7436] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/16/2021] [Accepted: 04/06/2022] [Indexed: 06/15/2023]
Abstract
Drosophila renal stem cells (RSCs) contradict the common expectation that stem cells maintain tissue homeostasis. RSCs are abundant, quiescent, and confined to the peri-ureter region of the kidney-like Malpighian tubules (MTs). Although derived during pupation-like intestinal stem cells, RSCs initially remodel the larval MTs only near the intestinal junction. However, following adult injury to the ureter by xanthine stones, RSCs remodel the damaged region in a similar manner. Thus, RSCs represent stem cells encoding a developmental redesign. The remodeled tubules have a larger luminal diameter and shorter brush border, changes linked to enhanced stone resistance. However, RSC-mediated modifications also raise salt sensitivity and reduce fecundity. Our results suggest that RSCs arose by arresting developmental progenitors to preserve larval physiology until a time in adulthood when it becomes advantageous to complete the development by RSC activation.
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9
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Niu W, Spradling AC. Mouse oocytes develop in cysts with the help of nurse cells. Cell 2022; 185:2576-2590.e12. [PMID: 35623357 DOI: 10.1016/j.cell.2022.05.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2021] [Revised: 03/07/2022] [Accepted: 05/02/2022] [Indexed: 10/18/2022]
Abstract
Mouse germline cysts, on average, develop into six oocytes supported by 24 nurse cells that transfer cytoplasm and organelles to generate a Balbiani body. We showed that between E14.5 and P5, cysts periodically activate some nurse cells to begin cytoplasmic transfer, which causes them to shrink and turnover within 2 days. Nurse cells die by a programmed cell death (PCD) pathway involving acidification, similar to Drosophila nurse cells, and only infrequently by apoptosis. Prior to initiating transfer, nurse cells co-cluster by scRNA-seq with their pro-oocyte sisters, but during their final 2 days, they cluster separately. The genes promoting oocyte development and nurse cell PCD are upregulated, whereas the genes that repress transfer, such as Tex14, and oocyte factors, such as Nobox and Lhx8, are under-expressed. The transferred nurse cell centrosomes build a cytocentrum that establishes a large microtubule aster in the primordial oocyte that organizes the Balbiani body, defining the earliest oocyte polarity.
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Affiliation(s)
- Wanbao Niu
- Howard Hughes Medical Institute Research Laboratories, Department of Embryology, Carnegie Institution for Science, Baltimore, MD 21218, USA
| | - Allan C Spradling
- Howard Hughes Medical Institute Research Laboratories, Department of Embryology, Carnegie Institution for Science, Baltimore, MD 21218, USA.
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10
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Urban JM, Foulk MS, Bliss JE, Coleman CM, Lu N, Mazloom R, Brown SJ, Spradling AC, Gerbi SA. High contiguity de novo genome assembly and DNA modification analyses for the fungus fly, Sciara coprophila, using single-molecule sequencing. BMC Genomics 2021; 22:643. [PMID: 34488624 PMCID: PMC8419958 DOI: 10.1186/s12864-021-07926-2] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2021] [Accepted: 08/08/2021] [Indexed: 12/26/2022] Open
Abstract
BACKGROUND The lower Dipteran fungus fly, Sciara coprophila, has many unique biological features that challenge the rule of genome DNA constancy. For example, Sciara undergoes paternal chromosome elimination and maternal X chromosome nondisjunction during spermatogenesis, paternal X elimination during embryogenesis, intrachromosomal DNA amplification of DNA puff loci during larval development, and germline-limited chromosome elimination from all somatic cells. Paternal chromosome elimination in Sciara was the first observation of imprinting, though the mechanism remains a mystery. Here, we present the first draft genome sequence for Sciara coprophila to take a large step forward in addressing these features. RESULTS We assembled the Sciara genome using PacBio, Nanopore, and Illumina sequencing. To find an optimal assembly using these datasets, we generated 44 short-read and 50 long-read assemblies. We ranked assemblies using 27 metrics assessing contiguity, gene content, and dataset concordance. The highest-ranking assemblies were scaffolded using BioNano optical maps. RNA-seq datasets from multiple life stages and both sexes facilitated genome annotation. A set of 66 metrics was used to select the first draft assembly for Sciara. Nearly half of the Sciara genome sequence was anchored into chromosomes, and all scaffolds were classified as X-linked or autosomal by coverage. CONCLUSIONS We determined that X-linked genes in Sciara males undergo dosage compensation. An entire bacterial genome from the Rickettsia genus, a group known to be endosymbionts in insects, was co-assembled with the Sciara genome, opening the possibility that Rickettsia may function in sex determination in Sciara. Finally, the signal level of the PacBio and Nanopore data support the presence of cytosine and adenine modifications in the Sciara genome, consistent with a possible role in imprinting.
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Affiliation(s)
- John M Urban
- Department of Molecular Biology, Cell Biology and Biochemistry, Brown University Division of Biology and Medicine, Sidney Frank Hall for Life Sciences, 185 Meeting Street, Providence, RI, 02912, USA.
- Department of Embryology, Carnegie Institution for Science, Howard Hughes Medical Institute Research Laboratories, 3520 San Martin Drive, Baltimore, MD, 21218, USA.
| | - Michael S Foulk
- Department of Molecular Biology, Cell Biology and Biochemistry, Brown University Division of Biology and Medicine, Sidney Frank Hall for Life Sciences, 185 Meeting Street, Providence, RI, 02912, USA
- Present Address: Department of Biology, Mercyhurst University, Erie, PA, 16546, USA
| | - Jacob E Bliss
- Department of Molecular Biology, Cell Biology and Biochemistry, Brown University Division of Biology and Medicine, Sidney Frank Hall for Life Sciences, 185 Meeting Street, Providence, RI, 02912, USA
| | - C Michelle Coleman
- KSU Bioinformatics Center, Kansas State University Division of Biology, Ackert Hall, Manhattan, Kansas, 66502, USA
| | - Nanyan Lu
- KSU Bioinformatics Center, Kansas State University Division of Biology, Ackert Hall, Manhattan, Kansas, 66502, USA
| | - Reza Mazloom
- KSU Bioinformatics Center, Kansas State University Division of Biology, Ackert Hall, Manhattan, Kansas, 66502, USA
| | - Susan J Brown
- KSU Bioinformatics Center, Kansas State University Division of Biology, Ackert Hall, Manhattan, Kansas, 66502, USA
| | - Allan C Spradling
- Department of Embryology, Carnegie Institution for Science, Howard Hughes Medical Institute Research Laboratories, 3520 San Martin Drive, Baltimore, MD, 21218, USA
| | - Susan A Gerbi
- Department of Molecular Biology, Cell Biology and Biochemistry, Brown University Division of Biology and Medicine, Sidney Frank Hall for Life Sciences, 185 Meeting Street, Providence, RI, 02912, USA.
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11
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Ikami K, Nuzhat N, Abbott H, Pandoy R, Haky L, Spradling AC, Tanner H, Lei L. Altered germline cyst formation and oogenesis in Tex14 mutant mice. Biol Open 2021; 10:269245. [PMID: 34156079 PMCID: PMC8249907 DOI: 10.1242/bio.058807] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2021] [Accepted: 05/12/2021] [Indexed: 11/24/2022] Open
Abstract
During oocyte differentiation in mouse fetal ovaries, sister germ cells are connected by intercellular bridges, forming germline cysts. Within the cyst, primary oocytes form via gaining cytoplasm and organelles from sister germ cells through germ cell connectivity. To uncover the role of intercellular bridges in oocyte differentiation, we analyzed mutant female mice lacking testis-expressed 14 (TEX14), a protein involved in intercellular bridge formation and stabilization. In Tex14 homozygous mutant fetal ovaries, germ cells divide to form a reduced number of cysts in which germ cells remained connected via syncytia or fragmented cell membranes, rather than normal intercellular bridges. Compared with wild-type cysts, homozygous mutant cysts fragmented at a higher frequency and produced a greatly reduced number of primary oocytes with precocious cytoplasmic enrichment and enlarged volume. By contrast, Tex14 heterozygous mutant germline cysts were less fragmented and generate primary oocytes at a reduced size. Moreover, enlarged primary oocytes in homozygous mutants were used more efficiently to sustain folliculogenesis than undersized heterozygous mutant primary oocytes. Our observations directly link the nature of fetal germline cysts to oocyte differentiation and development. Summary: Altered germline cyst formation and fragmentation due to defective germ cell connectivity leads to changes in oocyte differentiation and development in Tex14 mutant mice.
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Affiliation(s)
- Kanako Ikami
- Buck Institute for Research on Aging, 94949, Novato, CA, USA
| | - Nafisa Nuzhat
- Department of Cell and Developmental Biology, University of Michigan Medical School, 48109, Ann Arbor, MI, USA
| | - Haley Abbott
- Department of Cell and Developmental Biology, University of Michigan Medical School, 48109, Ann Arbor, MI, USA
| | - Ronald Pandoy
- Buck Institute for Research on Aging, 94949, Novato, CA, USA
| | - Lauren Haky
- Buck Institute for Research on Aging, 94949, Novato, CA, USA
| | - Allan C Spradling
- Department of Embryology, Carnegie Institution for Science, 21218, Baltimore, MD, USA
| | - Heather Tanner
- Buck Institute for Research on Aging, 94949, Novato, CA, USA
| | - Lei Lei
- Buck Institute for Research on Aging, 94949, Novato, CA, USA
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12
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DeLuca SZ, Ghildiyal M, Pang LY, Spradling AC. Differentiating Drosophila female germ cells initiate Polycomb silencing by regulating PRC2-interacting proteins. eLife 2020; 9:56922. [PMID: 32773039 PMCID: PMC7438113 DOI: 10.7554/elife.56922] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2020] [Accepted: 08/06/2020] [Indexed: 01/18/2023] Open
Abstract
Polycomb silencing represses gene expression and provides a molecular memory of chromatin state that is essential for animal development. We show that Drosophila female germline stem cells (GSCs) provide a powerful system for studying Polycomb silencing. GSCs have a non-canonical distribution of PRC2 activity and lack silenced chromatin like embryonic progenitors. As GSC daughters differentiate into nurse cells and oocytes, nurse cells, like embryonic somatic cells, silence genes in traditional Polycomb domains and in generally inactive chromatin. Developmentally controlled expression of two Polycomb repressive complex 2 (PRC2)-interacting proteins, Pcl and Scm, initiate silencing during differentiation. In GSCs, abundant Pcl inhibits PRC2-dependent silencing globally, while in nurse cells Pcl declines and newly induced Scm concentrates PRC2 activity on traditional Polycomb domains. Our results suggest that PRC2-dependent silencing is developmentally regulated by accessory proteins that either increase the concentration of PRC2 at target sites or inhibit the rate that PRC2 samples chromatin.
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Affiliation(s)
- Steven Z DeLuca
- Howard Hughes Medical Institute Research Laboratories Department of Embryology, Carnegie Institution for Science, Baltimore, United States
| | - Megha Ghildiyal
- Howard Hughes Medical Institute Research Laboratories Department of Embryology, Carnegie Institution for Science, Baltimore, United States
| | - Liang-Yu Pang
- Howard Hughes Medical Institute Research Laboratories Department of Embryology, Carnegie Institution for Science, Baltimore, United States
| | - Allan C Spradling
- Howard Hughes Medical Institute Research Laboratories Department of Embryology, Carnegie Institution for Science, Baltimore, United States
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13
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Wang C, Spradling AC. An abundant quiescent stem cell population in Drosophila Malpighian tubules protects principal cells from kidney stones. eLife 2020; 9:54096. [PMID: 32175841 PMCID: PMC7093152 DOI: 10.7554/elife.54096] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2019] [Accepted: 03/14/2020] [Indexed: 12/26/2022] Open
Abstract
Adult Drosophila Malpighian tubules have low rates of cell turnover but are vulnerable to damage caused by stones, like their mammalian counterparts, kidneys. We show that Drosophilarenal stem cells (RSCs) in the ureter and lower tubules comprise a unique, unipotent regenerative compartment. RSCs respond only to loss of nearby principal cells (PCs), cells critical for maintaining ionic balance. Large polyploid PCs are outnumbered by RSCs, which replace each lost cell with multiple PCs of lower ploidy. Notably, RSCs do not replenish principal cells or stellate cells in the upper tubules. RSCs generate daughters by asymmetric Notch signaling, yet RSCs remain quiescent (cell cycle-arrested) without damage. Nevertheless, the capacity for RSC-mediated repair extends the lifespan of flies carrying kidney stones. We propose that abundant, RSC-like stem cells exist in other tissues with low rates of turnover where they may have been mistaken for differentiated tissue cells.
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Affiliation(s)
- Chenhui Wang
- Howard Hughes Medical Institute Research Laboratories, Department of Embryology, Carnegie Institution for Science, Baltimore, United States
| | - Allan C Spradling
- Howard Hughes Medical Institute Research Laboratories, Department of Embryology, Carnegie Institution for Science, Baltimore, United States
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14
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Greenblatt EJ, Obniski R, Mical C, Spradling AC. Prolonged ovarian storage of mature Drosophila oocytes dramatically increases meiotic spindle instability. eLife 2019; 8:49455. [PMID: 31755866 PMCID: PMC6905857 DOI: 10.7554/elife.49455] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2019] [Accepted: 11/17/2019] [Indexed: 12/21/2022] Open
Abstract
Human oocytes frequently generate aneuploid embryos that subsequently miscarry. In contrast, Drosophila oocytes from outbred laboratory stocks develop fully regardless of maternal age. Since mature Drosophila oocytes are not extensively stored in the ovary under laboratory conditions like they are in the wild, we developed a system to investigate how storage affects oocyte quality. The developmental capacity of stored mature Drosophila oocytes decays in a precise manner over 14 days at 25°C. These oocytes are transcriptionally inactive and persist using ongoing translation of stored mRNAs. Ribosome profiling revealed a progressive 2.3-fold decline in average translational efficiency during storage that correlates with oocyte functional decay. Although normal bipolar meiotic spindles predominate during the first week, oocytes stored for longer periods increasingly show tripolar, monopolar and other spindle defects, and give rise to embryos that fail to develop due to aneuploidy. Thus, meiotic chromosome segregation in mature Drosophila oocytes is uniquely sensitive to prolonged storage. Our work suggests the chromosome instability of human embryos could be mitigated by reducing the period of time mature human oocytes are stored in the ovary prior to ovulation.
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Affiliation(s)
- Ethan J Greenblatt
- Department of Embryology, Howard Hughes Medical Institute Research Laboratories, Carnegie Institution for Science, Baltimore, United States
| | - Rebecca Obniski
- Department of Embryology, Howard Hughes Medical Institute Research Laboratories, Carnegie Institution for Science, Baltimore, United States
| | - Claire Mical
- Department of Embryology, Howard Hughes Medical Institute Research Laboratories, Carnegie Institution for Science, Baltimore, United States
| | - Allan C Spradling
- Department of Embryology, Howard Hughes Medical Institute Research Laboratories, Carnegie Institution for Science, Baltimore, United States
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15
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Kanca O, Zirin J, Garcia-Marques J, Knight SM, Yang-Zhou D, Amador G, Chung H, Zuo Z, Ma L, He Y, Lin WW, Fang Y, Ge M, Yamamoto S, Schulze KL, Hu Y, Spradling AC, Mohr SE, Perrimon N, Bellen HJ. An efficient CRISPR-based strategy to insert small and large fragments of DNA using short homology arms. eLife 2019; 8:e51539. [PMID: 31674908 PMCID: PMC6855806 DOI: 10.7554/elife.51539] [Citation(s) in RCA: 76] [Impact Index Per Article: 15.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2019] [Accepted: 10/31/2019] [Indexed: 12/31/2022] Open
Abstract
We previously reported a CRISPR-mediated knock-in strategy into introns of Drosophila genes, generating an attP-FRT-SA-T2A-GAL4-polyA-3XP3-EGFP-FRT-attP transgenic library for multiple uses (Lee et al., 2018a). The method relied on double stranded DNA (dsDNA) homology donors with ~1 kb homology arms. Here, we describe three new simpler ways to edit genes in flies. We create single stranded DNA (ssDNA) donors using PCR and add 100 nt of homology on each side of an integration cassette, followed by enzymatic removal of one strand. Using this method, we generated GFP-tagged proteins that mark organelles in S2 cells. We then describe two dsDNA methods using cheap synthesized donors flanked by 100 nt homology arms and gRNA target sites cloned into a plasmid. Upon injection, donor DNA (1 to 5 kb) is released from the plasmid by Cas9. The cassette integrates efficiently and precisely in vivo. The approach is fast, cheap, and scalable.
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Affiliation(s)
- Oguz Kanca
- Department of Molecular and Human GeneticsBaylor College of MedicineHoustonUnited States
- Jan and Dan Duncan Neurological Research Institute, Texas Children’s HospitalHoustonUnited States
| | - Jonathan Zirin
- Howard Hughes Medical Institute, Harvard Medical SchoolBostonUnited States
- Department of GeneticsHarvard Medical SchoolBostonUnited States
| | | | - Shannon Marie Knight
- Howard Hughes Medical Institute, Harvard Medical SchoolBostonUnited States
- Department of GeneticsHarvard Medical SchoolBostonUnited States
| | - Donghui Yang-Zhou
- Howard Hughes Medical Institute, Harvard Medical SchoolBostonUnited States
- Department of GeneticsHarvard Medical SchoolBostonUnited States
| | - Gabriel Amador
- Howard Hughes Medical Institute, Harvard Medical SchoolBostonUnited States
- Department of GeneticsHarvard Medical SchoolBostonUnited States
| | - Hyunglok Chung
- Department of Molecular and Human GeneticsBaylor College of MedicineHoustonUnited States
- Jan and Dan Duncan Neurological Research Institute, Texas Children’s HospitalHoustonUnited States
| | - Zhongyuan Zuo
- Department of Molecular and Human GeneticsBaylor College of MedicineHoustonUnited States
- Jan and Dan Duncan Neurological Research Institute, Texas Children’s HospitalHoustonUnited States
| | - Liwen Ma
- Department of Molecular and Human GeneticsBaylor College of MedicineHoustonUnited States
| | - Yuchun He
- Department of Molecular and Human GeneticsBaylor College of MedicineHoustonUnited States
- Howard Hughes Medical Institute, Baylor College of MedicineHoustonUnited States
| | - Wen-Wen Lin
- Department of Molecular and Human GeneticsBaylor College of MedicineHoustonUnited States
| | - Ying Fang
- Department of Molecular and Human GeneticsBaylor College of MedicineHoustonUnited States
| | - Ming Ge
- Department of Molecular and Human GeneticsBaylor College of MedicineHoustonUnited States
| | - Shinya Yamamoto
- Department of Molecular and Human GeneticsBaylor College of MedicineHoustonUnited States
- Jan and Dan Duncan Neurological Research Institute, Texas Children’s HospitalHoustonUnited States
- Program in Developmental BiologyBaylor College of MedicineHoustonUnited States
- Department of NeuroscienceBaylor College of MedicineHoustonUnited States
| | - Karen L Schulze
- Department of Molecular and Human GeneticsBaylor College of MedicineHoustonUnited States
- Jan and Dan Duncan Neurological Research Institute, Texas Children’s HospitalHoustonUnited States
- Howard Hughes Medical Institute, Baylor College of MedicineHoustonUnited States
| | - Yanhui Hu
- Howard Hughes Medical Institute, Harvard Medical SchoolBostonUnited States
- Department of GeneticsHarvard Medical SchoolBostonUnited States
| | - Allan C Spradling
- Department of EmbryologyHoward Hughes Medical Institute, Carnegie Institution for ScienceBaltimoreUnited States
| | - Stephanie E Mohr
- Howard Hughes Medical Institute, Harvard Medical SchoolBostonUnited States
- Department of GeneticsHarvard Medical SchoolBostonUnited States
| | - Norbert Perrimon
- Howard Hughes Medical Institute, Harvard Medical SchoolBostonUnited States
- Department of GeneticsHarvard Medical SchoolBostonUnited States
| | - Hugo J Bellen
- Department of Molecular and Human GeneticsBaylor College of MedicineHoustonUnited States
- Jan and Dan Duncan Neurological Research Institute, Texas Children’s HospitalHoustonUnited States
- Howard Hughes Medical Institute, Baylor College of MedicineHoustonUnited States
- Program in Developmental BiologyBaylor College of MedicineHoustonUnited States
- Department of NeuroscienceBaylor College of MedicineHoustonUnited States
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16
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Obniski R, Sieber M, Spradling AC. Dietary Lipids Modulate Notch Signaling and Influence Adult Intestinal Development and Metabolism in Drosophila. Dev Cell 2018; 47:98-111.e5. [PMID: 30220569 PMCID: PMC6894183 DOI: 10.1016/j.devcel.2018.08.013] [Citation(s) in RCA: 49] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2018] [Revised: 06/14/2018] [Accepted: 08/16/2018] [Indexed: 12/30/2022]
Abstract
Tissue homeostasis involves a complex balance of developmental signals and environmental cues that dictate stem cell function. We found that dietary lipids control enteroendocrine cell production from Drosophila posterior midgut stem cells. Dietary cholesterol influences new intestinal cell differentiation in an Hr96-dependent manner by altering the level and duration of Notch signaling. Exogenous lipids modulate Delta ligand and Notch extracellular domain stability and alter their trafficking in endosomal vesicles. Lipid-modulated Notch signaling occurs in other nutrient-dependent tissues, suggesting that Delta trafficking in many cells is sensitive to cellular sterol levels. These diet-mediated alterations in young animals contribute to a metabolic program that persists after the diet changes. A low-sterol diet also slows the proliferation of enteroendocrine tumors initiated by Notch pathway disruption. Thus, a specific dietary nutrient can modify a key intercellular signaling pathway to shift stem cell differentiation and cause lasting changes in tissue structure and physiology.
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Affiliation(s)
- Rebecca Obniski
- Department of Embryology, Howard Hughes Medical Institute Research Laboratories, Carnegie Institution for Science, 3520 San Martin Drive, Baltimore, MD 21218, USA
| | - Matthew Sieber
- Department of Embryology, Howard Hughes Medical Institute Research Laboratories, Carnegie Institution for Science, 3520 San Martin Drive, Baltimore, MD 21218, USA; Department of Physiology, University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX 75390-9040, USA
| | - Allan C Spradling
- Department of Embryology, Howard Hughes Medical Institute Research Laboratories, Carnegie Institution for Science, 3520 San Martin Drive, Baltimore, MD 21218, USA.
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17
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Greenblatt EJ, Spradling AC. Fragile X mental retardation 1 gene enhances the translation of large autism-related proteins. Science 2018; 361:709-712. [PMID: 30115809 PMCID: PMC6905618 DOI: 10.1126/science.aas9963] [Citation(s) in RCA: 88] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2018] [Revised: 05/05/2018] [Accepted: 06/27/2018] [Indexed: 11/02/2022]
Abstract
Mutations in the fragile X mental retardation 1 gene (FMR1) cause the most common inherited human autism spectrum disorder. FMR1 influences messenger RNA (mRNA) translation, but identifying functional targets has been difficult. We analyzed quiescent Drosophila oocytes, which, like neural synapses, depend heavily on translating stored mRNA. Ribosome profiling revealed that FMR1 enhances rather than represses the translation of mRNAs that overlap previously identified FMR1 targets, and acts preferentially on large proteins. Human homologs of at least 20 targets are associated with dominant intellectual disability, and 30 others with recessive neurodevelopmental dysfunction. Stored oocytes lacking FMR1 usually generate embryos with severe neural defects, unlike stored wild-type oocytes, which suggests that translation of multiple large proteins by stored mRNAs is defective in fragile X syndrome and possibly other autism spectrum disorders.
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Affiliation(s)
- Ethan J Greenblatt
- Howard Hughes Medical Institute Research Laboratories, Department of Embryology, Carnegie Institution for Science, Baltimore, MD 21218, USA
| | - Allan C Spradling
- Howard Hughes Medical Institute Research Laboratories, Department of Embryology, Carnegie Institution for Science, Baltimore, MD 21218, USA.
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18
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Lee PT, Zirin J, Kanca O, Lin WW, Schulze KL, Li-Kroeger D, Tao R, Devereaux C, Hu Y, Chung V, Fang Y, He Y, Pan H, Ge M, Zuo Z, Housden BE, Mohr SE, Yamamoto S, Levis RW, Spradling AC, Perrimon N, Bellen HJ. A gene-specific T2A-GAL4 library for Drosophila. eLife 2018; 7:35574. [PMID: 29565247 PMCID: PMC5898912 DOI: 10.7554/elife.35574] [Citation(s) in RCA: 144] [Impact Index Per Article: 24.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2018] [Accepted: 03/16/2018] [Indexed: 12/18/2022] Open
Abstract
We generated a library of ~1000 Drosophila stocks in which we inserted a construct in the intron of genes allowing expression of GAL4 under control of endogenous promoters while arresting transcription with a polyadenylation signal 3’ of the GAL4. This allows numerous applications. First, ~90% of insertions in essential genes cause a severe loss-of-function phenotype, an effective way to mutagenize genes. Interestingly, 12/14 chromosomes engineered through CRISPR do not carry second-site lethal mutations. Second, 26/36 (70%) of lethal insertions tested are rescued with a single UAS-cDNA construct. Third, loss-of-function phenotypes associated with many GAL4 insertions can be reverted by excision with UAS-flippase. Fourth, GAL4 driven UAS-GFP/RFP reports tissue and cell-type specificity of gene expression with high sensitivity. We report the expression of hundreds of genes not previously reported. Finally, inserted cassettes can be replaced with GFP or any DNA. These stocks comprise a powerful resource for assessing gene function. Determining what role newly discovered genes play in the body is an important part of genetics. This task requires a lot of extra information about each gene, such as the specific cells where the gene is active, or what happens when the gene is deleted. To answer these questions, researchers need tools and methods to manipulate genes within a living organism. The fruit fly Drosophila is useful for such experiments because a toolbox of genetic techniques is already available. Gene editing in fruit flies allows small pieces of genetic information to be removed from or added to anywhere in the animal’s DNA. Another tool, known as GAL4-UAS, is a two-part system used to study gene activity. The GAL4 component is a protein that switches on genes. GAL4 alone does very little in Drosophila cells because it only recognizes a DNA sequence called UAS. However, if a GAL4-producing cell is also engineered to contain a UAS-controlled gene, GAL4 will switch the gene on. Lee et al. used gene editing to insert a small piece of DNA, containing the GAL4 sequence followed by a ‘stop’ signal, into many different fly genes. The insertion made the cells where each gene was normally active produce GAL4, but – thanks to the stop signal – rendered the rest of the original gene non-functional. This effectively deleted the proteins encoded by each gene, giving information about the biological processes they normally control. Lee et al. went on to use their insertion approach to make a Drosophila genetic library. This is a collection of around 1,000 different strains of fly, each carrying the GAL4/stop combination in a single gene. The library allows any gene in the collection to be studied in detail simply by combining the GAL4 with different UAS-controlled genetic tools. For example, introducing a UAS-controlled marker would pinpoint where in the body the original gene was active. Alternatively, adding UAS-controlled human versions of the gene would create humanized flies, which are a valuable tool to study potential disease-causing genes in humans. This Drosophila library is a resource that contributes new experimental tools to fly genetics. Insights gained from flies can also be applied to more complex animals like humans, especially since around 65% of genes are similar across humans and Drosophila. As such, Lee et al. hope that this resource will help other researchers shed new light on the role of many different genes in health and disease.
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Affiliation(s)
- Pei-Tseng Lee
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, United States
| | - Jonathan Zirin
- Department of Genetics, Harvard Medical School, Boston, United States
| | - Oguz Kanca
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, United States
| | - Wen-Wen Lin
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, United States
| | - Karen L Schulze
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, United States.,Howard Hughes Medical Institute, Baylor College of Medicine, Houston, United States
| | - David Li-Kroeger
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, United States
| | - Rong Tao
- Department of Genetics, Harvard Medical School, Boston, United States
| | - Colby Devereaux
- Department of Genetics, Harvard Medical School, Boston, United States
| | - Yanhui Hu
- Department of Genetics, Harvard Medical School, Boston, United States
| | - Verena Chung
- Department of Genetics, Harvard Medical School, Boston, United States
| | - Ying Fang
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, United States
| | - Yuchun He
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, United States.,Howard Hughes Medical Institute, Baylor College of Medicine, Houston, United States
| | - Hongling Pan
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, United States.,Howard Hughes Medical Institute, Baylor College of Medicine, Houston, United States
| | - Ming Ge
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, United States
| | - Zhongyuan Zuo
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, United States.,Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, Houston, United States
| | | | - Stephanie E Mohr
- Department of Genetics, Harvard Medical School, Boston, United States.,Howard Hughes Medical Institute, Harvard Medical School, Boston, United States
| | - Shinya Yamamoto
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, United States.,Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, Houston, United States.,Program in Developmental Biology, Baylor College of Medicine, Houston, United States.,Department of Neuroscience, Baylor College of Medicine, Houston, United States
| | - Robert W Levis
- Department of Embryology, Howard Hughes Medical Institute, Carnegie Institution for Science, Baltimore, United States
| | - Allan C Spradling
- Department of Embryology, Howard Hughes Medical Institute, Carnegie Institution for Science, Baltimore, United States
| | - Norbert Perrimon
- Department of Genetics, Harvard Medical School, Boston, United States.,Howard Hughes Medical Institute, Harvard Medical School, Boston, United States
| | - Hugo J Bellen
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, United States.,Howard Hughes Medical Institute, Baylor College of Medicine, Houston, United States.,Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, Houston, United States.,Program in Developmental Biology, Baylor College of Medicine, Houston, United States.,Department of Neuroscience, Baylor College of Medicine, Houston, United States
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19
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Abstract
Polytene chromosomes have for 80 years provided the highest resolution view of interphase genome structure in an animal cell nucleus. These chromosomes represent the normal genomic state of nearly all Drosophila larval and many adult cells, and a better understanding of their striking banded structure has been sought for decades. A more recently appreciated characteristic of Drosophila polytene cells is somatic genome instability caused by unfinished replication (UR). Repair of stalled forks generates enough deletions in polytene salivary gland cells to alter 10%-90% of the DNA strands within more than 100 UR regions comprising 20% of the euchromatic genome. We accurately map UR regions and show that most approximate large polytene bands, indicating that replication forks frequently stall near band boundaries in late S phase. Chromosome conformation capture has recently identified dense topologically associated domains (TADs) in many genomes and most UR bands are similar or slightly smaller than a cognate Drosophila TAD. We argue that bands serve the evolutionarily ancient function of coordinating genome replication with local gene activity. We also discuss the relatively recent evolution of polyteny and somatic instability in Diptera and propose that these processes helped propel the amazing success of two-winged flies in becoming the most ecologically diverse insect group, with 200 times the number of species as mammals.
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Affiliation(s)
- Allan C Spradling
- Department of Embryology, Howard Hughes Medical Institute, Carnegie Institution for Science, Baltimore, Maryland 21218
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20
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Sieber MH, Spradling AC. The role of metabolic states in development and disease. Curr Opin Genet Dev 2017; 45:58-68. [PMID: 28347941 PMCID: PMC6894399 DOI: 10.1016/j.gde.2017.03.002] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2016] [Revised: 02/23/2017] [Accepted: 03/02/2017] [Indexed: 12/17/2022]
Abstract
During development, cells adopt distinct metabolic strategies to support growth, produce energy, and meet the demands of a mature tissue. Some of these metabolic states maintain a constrained program of nutrient utilization, while others providing metabolic flexibility as a means to couple developmental progression with nutrient availability. Here we discuss our understanding of metabolic programs, and how they support specific aspects of animal development. During phases of rapid proliferation a subset of metabolic programs provide the building blocks to support growth. During differentiation, metabolic programs shift to support the unique demands of each tissue. Finally, we discuss how a model system, such as Drosophila egg development, can provide a versatile platform to discover novel mechanisms controlling programmed shift in metabolism.
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Affiliation(s)
- Matthew H Sieber
- Department of Embryology, Howard Hughes Medical Institute Labs, Carnegie Institution for Science, Baltimore, MD 21218, United States
| | - Allan C Spradling
- Department of Embryology, Howard Hughes Medical Institute Labs, Carnegie Institution for Science, Baltimore, MD 21218, United States.
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21
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Abstract
Lineage analysis is widely used because it provides a very powerful tool for characterizing the developmental behavior of the cells in vivo. In this chapter, we describe a particularly informative variant of lineage analysis that we term "single-cell lineage analysis". As in traditional lineage analysis, the method employs a Tamoxifen (Tmx)-inducible CAGCreER mouse line, which is crossed to an R26R reporter line that can be activated by Cre-mediated DNA recombination. However, instead of driving CreER at a high level within a subset of cells defined by a particular promoter, CreER is driven with a generic promoter that is active in essentially all cells throughout the lifespan of the mouse. Specificity comes from using only a very low dose of Tmx so that just a few random, widely separated individual cells undergo recombination and become labeled. The growth and behavior of most such initially marked cells can subsequently be followed over time because each one forms a growing clone of marked cells that does not overlap with other clones due to their rarity. Following individual cell growth patterns provides much more information than can be derived from traditional lineage analysis, which relies on promoter specificity and uses high doses of Tmx that cannot resolve the behavior of single cells. We illustrate the value of single-cell lineage analysis using a recent study of fetal germ cell development and a recent search for female germ-line stem cells in adult mouse ovaries.
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Affiliation(s)
- Lei Lei
- Department of Cell and Developmental Biology, University of Michigan Medical School, 109 Zina Pitcher Place, 3045 BSRB, Ann Arbor, MI, 48109, USA.
| | - Allan C Spradling
- Department of Embryology, Howard Hughes Medical Institute, Carnegie Institution for Science, 3520 San Martin Dr., Baltimore, MD, 21218, USA.
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22
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Sieber MH, Thomsen MB, Spradling AC. Electron Transport Chain Remodeling by GSK3 during Oogenesis Connects Nutrient State to Reproduction. Cell 2016; 164:420-32. [PMID: 26824655 PMCID: PMC6894174 DOI: 10.1016/j.cell.2015.12.020] [Citation(s) in RCA: 95] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2015] [Revised: 10/30/2015] [Accepted: 11/26/2015] [Indexed: 11/28/2022]
Abstract
Reproduction is heavily influenced by nutrition and metabolic state. Many common reproductive disorders in humans are associated with diabetes and metabolic syndrome. We characterized the metabolic mechanisms that support oogenesis and found that mitochondria in mature Drosophila oocytes enter a low-activity state of respiratory quiescence by remodeling the electron transport chain (ETC). This shift in mitochondrial function leads to extensive glycogen accumulation late in oogenesis and is required for the developmental competence of the oocyte. Decreased insulin signaling initiates ETC remodeling and mitochondrial respiratory quiescence through glycogen synthase kinase 3 (GSK3). Intriguingly, we observed similar ETC remodeling and glycogen uptake in maturing Xenopus oocytes, suggesting that these processes are evolutionarily conserved aspects of oocyte development. Our studies reveal an important link between metabolism and oocyte maturation.
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Affiliation(s)
- Matthew H Sieber
- Department of Embryology, Carnegie Institution of Washington, 3520 San Martin Drive, Baltimore, MD 21218, USA
| | - Michael B Thomsen
- Department of Biology, Johns Hopkins University, 3400 North Charles Street, Baltimore, MD 21218, USA
| | - Allan C Spradling
- Department of Embryology, Carnegie Institution of Washington, 3520 San Martin Drive, Baltimore, MD 21218, USA; Howard Hughes Medical Institute, Chevy Chase, MD 20815, USA.
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23
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Losick VP, Jun AS, Spradling AC. Wound-Induced Polyploidization: Regulation by Hippo and JNK Signaling and Conservation in Mammals. PLoS One 2016; 11:e0151251. [PMID: 26958853 PMCID: PMC4784922 DOI: 10.1371/journal.pone.0151251] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2016] [Accepted: 02/25/2016] [Indexed: 12/13/2022] Open
Abstract
Tissue integrity and homeostasis often rely on the proliferation of stem cells or differentiated cells to replace lost, aged, or damaged cells. Recently, we described an alternative source of cell replacement- the expansion of resident, non-dividing diploid cells by wound-induced polyploidization (WIP). Here we show that the magnitude of WIP is proportional to the extent of cell loss using a new semi-automated assay with single cell resolution. Hippo and JNK signaling regulate WIP; unexpectedly however, JNK signaling through AP-1 limits rather than stimulates the level of Yki activation and polyploidization in the Drosophila epidermis. We found that polyploidization also quantitatively compensates for cell loss in a mammalian tissue, mouse corneal endothelium, where increased cell death occurs with age in a mouse model of Fuchs Endothelial Corneal Dystrophy (FECD). Our results suggest that WIP is an evolutionarily conserved homeostatic mechanism that maintains the size and synthetic capacity of adult tissues.
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Affiliation(s)
- Vicki P. Losick
- Department of Embryology, Carnegie Institution for Science, Howard Hughes Medical Institute, 3250 San Martin Dr., Baltimore, MD 21218, United States of America
| | - Albert S. Jun
- Wilmer Eye Institute, Johns Hopkins School of Medicine, 400 N. Broadway, Baltimore, MD 21231, United States of America
| | - Allan C. Spradling
- Department of Embryology, Carnegie Institution for Science, Howard Hughes Medical Institute, 3250 San Martin Dr., Baltimore, MD 21218, United States of America
- * E-mail:
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24
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Lei L, Spradling AC. Mouse oocytes differentiate through organelle enrichment from sister cyst germ cells. Science 2016; 352:95-9. [PMID: 26917595 PMCID: PMC6910648 DOI: 10.1126/science.aad2156] [Citation(s) in RCA: 177] [Impact Index Per Article: 22.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2015] [Accepted: 02/11/2016] [Indexed: 12/29/2022]
Abstract
Oocytes differentiate in diverse species by receiving organelles and cytoplasm from sister germ cells while joined in germline cysts or syncytia. Mouse primordial germ cells form germline cysts, but the role of cysts in oogenesis is unknown. We find that mouse germ cells receive organelles from neighboring cyst cells and build a Balbiani body to become oocytes, whereas nurselike germ cells die. Organelle movement, Balbiani body formation, and oocyte fate determination are selectively blocked by low levels of microtubule-dependent transport inhibitors. Membrane breakdown within the cyst and an apoptosis-like process are associated with organelle transfer into the oocyte, events reminiscent of nurse cell dumping in Drosophila We propose that cytoplasmic and organelle transport plays an evolutionarily conserved and functionally important role in mammalian oocyte differentiation.
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Affiliation(s)
- Lei Lei
- Howard Hughes Medical Institute Research Laboratories, Department of Embryology, Carnegie Institution for Science, 3520 San Martin Drive, Baltimore, MD 21218, USA.
| | - Allan C Spradling
- Howard Hughes Medical Institute Research Laboratories, Department of Embryology, Carnegie Institution for Science, 3520 San Martin Drive, Baltimore, MD 21218, USA.
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25
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Nagarkar-Jaiswal S, DeLuca SZ, Lee PT, Lin WW, Pan H, Zuo Z, Lv J, Spradling AC, Bellen HJ. A genetic toolkit for tagging intronic MiMIC containing genes. eLife 2015; 4. [PMID: 26102525 PMCID: PMC4499919 DOI: 10.7554/elife.08469] [Citation(s) in RCA: 102] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2015] [Accepted: 06/22/2015] [Indexed: 12/20/2022] Open
Abstract
Previously, we described a large collection of Minos-Mediated Integration Cassettes (MiMICs) that contain two phiC31 recombinase target sites and allow the generation of a new exon that encodes a protein tag when the MiMIC is inserted in a codon intron (Nagarkar-Jaiswal et al., 2015). These modified genes permit numerous applications including assessment of protein expression pattern, identification of protein interaction partners by immunoprecipitation followed by mass spec, and reversible removal of the tagged protein in any tissue. At present, these conversions remain time and labor-intensive as they require embryos to be injected with plasmid DNA containing the exon tag. In this study, we describe a simple and reliable genetic strategy to tag genes/proteins that contain MiMIC insertions using an integrated exon encoding GFP flanked by FRT sequences. We document the efficiency and tag 60 mostly uncharacterized genes.
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Affiliation(s)
| | - Steven Z DeLuca
- Department of Embryology, Howard Hughes Medical Institute, Carnegie Institution for Science, Baltimore, United States
| | - Pei-Tseng Lee
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, United States
| | - Wen-Wen Lin
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, United States
| | - Hongling Pan
- Howard Hughes Medical Institute, Baylor College of Medicine, Houston, United States
| | - Zhongyuan Zuo
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, United States
| | - Jiangxing Lv
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, United States
| | - Allan C Spradling
- Department of Embryology, Howard Hughes Medical Institute, Carnegie Institution for Science, Baltimore, United States
| | - Hugo J Bellen
- Howard Hughes Medical Institute, Baylor College of Medicine, Houston, United States
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Nagarkar-Jaiswal S, Lee PT, Campbell ME, Chen K, Anguiano-Zarate S, Gutierrez MC, Busby T, Lin WW, He Y, Schulze KL, Booth BW, Evans-Holm M, Venken KJT, Levis RW, Spradling AC, Hoskins RA, Bellen HJ. A library of MiMICs allows tagging of genes and reversible, spatial and temporal knockdown of proteins in Drosophila. eLife 2015; 4. [PMID: 25824290 PMCID: PMC4379497 DOI: 10.7554/elife.05338] [Citation(s) in RCA: 251] [Impact Index Per Article: 27.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2014] [Accepted: 02/06/2015] [Indexed: 01/19/2023] Open
Abstract
Here, we document a collection of ∼7434 MiMIC (Minos Mediated Integration Cassette) insertions of which 2854 are inserted in coding introns. They allowed us to create a library of 400 GFP-tagged genes. We show that 72% of internally tagged proteins are functional, and that more than 90% can be imaged in unfixed tissues. Moreover, the tagged mRNAs can be knocked down by RNAi against GFP (iGFPi), and the tagged proteins can be efficiently knocked down by deGradFP technology. The phenotypes associated with RNA and protein knockdown typically correspond to severe loss of function or null mutant phenotypes. Finally, we demonstrate reversible, spatial, and temporal knockdown of tagged proteins in larvae and adult flies. This new strategy and collection of strains allows unprecedented in vivo manipulations in flies for many genes. These strategies will likely extend to vertebrates. DOI:http://dx.doi.org/10.7554/eLife.05338.001 In the last few decades, technical advances in altering the genes of organisms have led to many discoveries about how genes work. For example, it is now possible to add a specific DNA sequence to a gene so that the protein it makes will carry a ‘tag’ that enables us to track it in cells. One such tag is called green fluorescent protein (GFP) and it is often used to study other proteins in living cells because it produces green fluorescence that can be detected under a microscope. It is labor intensive to add tags to individual genes, so this limits the number of proteins that can be studied in this way. In 2011, researchers developed a new method that can easily tag many genes in fruit flies. It makes use of small sections of DNA called transposons, which are able to move around the genome by ‘cutting’ themselves out of one location and ‘pasting’ themselves in somewhere else. The researchers used a transposon called Minos, which is naturally found in fruit flies. When Minos inserts into a gene, it often disrupts the gene and stops it from working. However, the researchers could swap the inserted transposon for a gene encoding GFP by making use of a natural process that rearranges DNA in cells. This resulted in the protein encoded by the gene containing GFP and so it can be detected under a microscope. This method allowed the researchers to create a collection of fly lines that have the GFP tag on many different proteins. Now, Nagarkar-Jaiswal et al. have greatly expanded this initial collection. More than 75% of GFP-tagged proteins worked normally and the flies producing these altered proteins remain healthy. It is possible to use a technique called RNA interference against the GFP to lower the production of the tagged proteins. Moreover, Nagarkar-Jaiswal et al. show that it is also possible to degrade the tagged proteins so that less protein is present. The removal of proteins is reversible and can be done in specific tissues during any phase in fly development. These techniques allow researchers to directly associate the loss of the protein with the consequences for the fly. This collection of fruit fly lines is a useful resource that can help us understand how genes work. The method for tagging the proteins could also be modified to work in other animals. DOI:http://dx.doi.org/10.7554/eLife.05338.002
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Affiliation(s)
- Sonal Nagarkar-Jaiswal
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, United States
| | - Pei-Tseng Lee
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, United States
| | - Megan E Campbell
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, United States
| | - Kuchuan Chen
- Program in Developmental Biology, Baylor College of Medicine, Houston, United States
| | | | - Manuel Cantu Gutierrez
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, United States
| | - Theodore Busby
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, United States
| | - Wen-Wen Lin
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, United States
| | - Yuchun He
- Howard Hughes Medical Institute, Baylor College of Medicine, Houston, United States
| | - Karen L Schulze
- Howard Hughes Medical Institute, Baylor College of Medicine, Houston, United States
| | - Benjamin W Booth
- Life Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, United States
| | - Martha Evans-Holm
- Life Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, United States
| | - Koen J T Venken
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, United States
| | - Robert W Levis
- Department of Embryology, Howard Hughes Medical Institute, Carnegie Institution for Science, Baltimore, United States
| | - Allan C Spradling
- Department of Embryology, Howard Hughes Medical Institute, Carnegie Institution for Science, Baltimore, United States
| | - Roger A Hoskins
- Life Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, United States
| | - Hugo J Bellen
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, United States
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Deady LD, Shen W, Mosure SA, Spradling AC, Sun J. Matrix metalloproteinase 2 is required for ovulation and corpus luteum formation in Drosophila. PLoS Genet 2015; 11:e1004989. [PMID: 25695427 PMCID: PMC4335033 DOI: 10.1371/journal.pgen.1004989] [Citation(s) in RCA: 58] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2014] [Accepted: 01/06/2015] [Indexed: 01/08/2023] Open
Abstract
Ovulation is critical for successful reproduction and correlates with ovarian cancer risk, yet genetic studies of ovulation have been limited. It has long been thought that the mechanism controlling ovulation is highly divergent due to speciation and fast evolution. Using genetic tools available in Drosophila, we now report that ovulation in Drosophila strongly resembles mammalian ovulation at both the cellular and molecular levels. Just one of up to 32 mature follicles per ovary pair loses posterior follicle cells (“trimming”) and protrudes into the oviduct, showing that a selection process prefigures ovulation. Follicle cells that remain after egg release form a “corpus luteum (CL)” at the end of the ovariole, develop yellowish pigmentation, and express genes encoding steroid hormone biosynthetic enzymes that are required for full fertility. Finally, matrix metalloproteinase 2 (Mmp2), a type of protease thought to facilitate mammalian ovulation, is expressed in mature follicle and CL cells. Mmp2 activity is genetically required for trimming, ovulation and CL formation. Our studies provide new insights into the regulation of Drosophila ovulation and establish Drosophila as a model for genetically investigating ovulation in diverse organisms, including mammals. Sexual reproduction is thought to be a highly divergent process due to fast evolution and speciation. For example, sperm from one species can seldom fertilize eggs from another species, indicating that different molecular machinery for fertilization is applied in different species. In contrast to this divergent view, ovulation, the process of liberating mature eggs from the ovary, is a general phenomenon throughout the Metazoa. We provide evidence that basic mechanisms of ovulation are conserved. Like mammalian follicles, Drosophila follicles consist of single oocytes surrounded by a layer of follicle cells. Drosophila follicles degrade their posterior follicle cells to allow the oocyte to rupture into the oviduct during ovulation. The residual postovulatory follicles reside in the ovary, accumulate yellowish pigmentation, and produce the steroid hormone ecdysone, features which resemble the mammalian corpus luteum. We also showed that matrix metalloproteinase, a type of proteinase proposed to degrade the mammalian follicle wall during ovulation, is required in Drosophila for posterior follicle cell degradation and ovulation. These findings are particularly important because this simple genetic model system will speed up the identification of many conserved regulators required for regulating matrix metalloproteinase activity and ovulation in human, processes that influence ovarian cancer formation and cancer metastasis.
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Affiliation(s)
- Lylah D. Deady
- Department of Physiology & Neurobiology, University of Connecticut, Storrs, Storrs, Connecticut, United States of America
| | - Wei Shen
- Department of Physiology & Neurobiology, University of Connecticut, Storrs, Storrs, Connecticut, United States of America
| | - Sarah A. Mosure
- Department of Physiology & Neurobiology, University of Connecticut, Storrs, Storrs, Connecticut, United States of America
| | - Allan C. Spradling
- Howard Hughes Medical Institute Research Laboratories, Department of Embryology, Carnegie Institution for Science, Baltimore, Maryland, United States of America
- * E-mail: (ACS); (JS)
| | - Jianjun Sun
- Department of Physiology & Neurobiology, University of Connecticut, Storrs, Storrs, Connecticut, United States of America
- Institute for Systems Genomics, University of Connecticut, Storrs, Storrs, Connecticut, United States of America
- * E-mail: (ACS); (JS)
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Lee MC, Spradling AC. The progenitor state is maintained by lysine-specific demethylase 1-mediated epigenetic plasticity during Drosophila follicle cell development. Genes Dev 2015; 28:2739-49. [PMID: 25512561 PMCID: PMC4265677 DOI: 10.1101/gad.252692.114] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Progenitors are early lineage cells that proliferate before the onset of terminal differentiation. Although widespread, the epigenetic mechanisms that control the progenitor state and the onset of differentiation remain elusive. By studying Drosophila ovarian follicle cell progenitors, we identified lysine-specific demethylase 1 (lsd1) and CoRest as differentiation regulators using a GAL4∷GFP variegation assay. The follicle cell progenitors in lsd1 or CoRest heterozygotes prematurely lose epigenetic plasticity, undergo the Notch-dependent mitotic-endocycle transition, and stop dividing before a normal number of follicle cells can be produced. Simultaneously reducing the dosage of the histone H3K4 methyltransferase Trithorax reverses these effects, suggesting that an Lsd1/CoRest complex times progenitor differentiation by controlling the stability of H3K4 methylation levels. Individual cells or small clones initially respond to Notch; hence, a critical level of epigenetic stabilization is acquired cell-autonomously and initiates differentiation by making progenitors responsive to pre-existing external signals.
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Affiliation(s)
- Ming-Chia Lee
- Howard Hughes Medical Institute Research Laboratories, Department of Embryology, Carnegie Institution, Baltimore, Maryland 21218, USA
| | - Allan C Spradling
- Howard Hughes Medical Institute Research Laboratories, Department of Embryology, Carnegie Institution, Baltimore, Maryland 21218, USA
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29
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Abstract
DNA replication remains unfinished in many Drosophila polyploid cells, which harbor disproportionately fewer copies of late-replicating chromosomal regions. Using NextGen sequencing of DNA from giant polytene cells of the larval salivary gland, Yarosh and Spradling show that sporadic, incomplete replication during the endocycle S phase alters the Drosophila genome at thousands of sites that differ in every cell; similar events occur in the ovary. The authors propose that the extensive somatic DNA instability described here underlies position effect variegation and molds the structure of polytene chromosomes. DNA replication remains unfinished in many Drosophila polyploid cells, which harbor disproportionately fewer copies of late-replicating chromosomal regions. By analyzing paired-end high-throughput sequence data from polytene larval salivary gland cells, we define 112 underreplicated (UR) euchromatic regions 60–480 kb in size. To determine the effects of underreplication on genome integrity, we analyzed anomalous read pairs and breakpoint reads throughout the euchromatic genome. Each UR euchromatic region contains many different deletions 10–500 kb in size, while very few deletions are present in fully replicated chromosome regions or UR zones from embryo DNA. Thus, during endocycles, stalled forks within UR regions break and undergo local repair instead of remaining stable and generating nested forks. As a result, each salivary gland cell contains hundreds of unique deletions that account for their copy number reductions. Similar UR regions and deletions were observed in ovarian DNA, suggesting that incomplete replication, fork breakage, and repair occur widely in polytene cells. UR regions are enriched in genes encoding immunoglobulin superfamily proteins and contain many neurally expressed and homeotic genes. We suggest that the extensive somatic DNA instability described here underlies position effect variegation, molds the structure of polytene chromosomes, and should be investigated for possible functions.
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Affiliation(s)
- Will Yarosh
- Howard Hughes Medical Institute, Department of Embryology, Carnegie Institution for Science, Baltimore, Maryland 21218, USA
| | - Allan C Spradling
- Howard Hughes Medical Institute, Department of Embryology, Carnegie Institution for Science, Baltimore, Maryland 21218, USA
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Losick VP, Fox DT, Spradling AC. Polyploidization and cell fusion contribute to wound healing in the adult Drosophila epithelium. Curr Biol 2013; 23:2224-2232. [PMID: 24184101 PMCID: PMC3898104 DOI: 10.1016/j.cub.2013.09.029] [Citation(s) in RCA: 147] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2013] [Revised: 08/19/2013] [Accepted: 09/13/2013] [Indexed: 12/17/2022]
Abstract
BACKGROUND Reestablishing epithelial integrity and biosynthetic capacity is critically important following tissue damage. The adult Drosophila abdominal epithelium provides an attractive new system to address how postmitotic diploid cells contribute to repair. RESULTS Puncture wounds to the adult Drosophila epidermis close initially by forming a melanized scab. We found that epithelial cells near the wound site fuse to form a giant syncytium, which sends lamellae under the scab to re-epithelialize the damaged site. Other large cells arise more peripherally by initiating endocycles and becoming polyploid, or by cell fusion. Rac GTPase activity is needed for syncytium formation, while the Hippo signaling effector Yorkie modulates both polyploidization and cell fusion. Large cell formation is functionally important because when both polyploidization and fusion are blocked, wounds do not re-epithelialize. CONCLUSIONS Our observations indicate that cell mass lost upon wounding can be replaced by polyploidization instead of mitotic proliferation. We propose that large cells generated by polyploidization or cell fusion are essential because they are better able than diploid cells to mechanically stabilize wounds, especially those containing permanent acellular structures, such as scar tissue.
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Affiliation(s)
- Vicki P Losick
- Department of Embryology, Carnegie Institution for Science, Howard Hughes Medical Institute, 3520 San Martin Drive, Baltimore, MD 21218, USA
| | - Donald T Fox
- Department of Pharmacology and Cancer Biology and Department of Cell Biology, Duke University Medical Center, C318 LSRC Box 3813, Durham, NC 27710, USA
| | - Allan C Spradling
- Department of Embryology, Carnegie Institution for Science, Howard Hughes Medical Institute, 3520 San Martin Drive, Baltimore, MD 21218, USA.
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Abstract
The Drosophila midgut is maintained throughout its length by superficially similar, multipotent intestinal stem cells that generate new enterocytes and enteroendocrine cells in response to tissue requirements. We found that the midgut shows striking regional differentiation along its anterior-posterior axis. At least ten distinct subregions differ in cell morphology, physiology and the expression of hundreds of genes with likely tissue functions. Stem cells also vary regionally in behavior and gene expression, suggesting that they contribute to midgut sub-specialization. Clonal analyses showed that stem cells generate progeny located outside their own subregion at only one of six borders tested, suggesting that midgut subregions resemble cellular compartments involved in tissue development. Tumors generated by disrupting Notch signaling arose preferentially in three subregions and tumor cells also appeared to respect regional borders. Thus, apparently similar intestinal stem cells differ regionally in cell production, gene expression and in the ability to spawn tumors. DOI:http://dx.doi.org/10.7554/eLife.00886.001.
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Affiliation(s)
- Alexis Marianes
- Department of Embryology , Howard Hughes Medical Institute, Carnegie Institution for Science , Baltimore , United States
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32
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Sun J, Spradling AC. Ovulation in Drosophila is controlled by secretory cells of the female reproductive tract. eLife 2013; 2:e00415. [PMID: 23599892 PMCID: PMC3628084 DOI: 10.7554/elife.00415] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2012] [Accepted: 03/08/2013] [Indexed: 12/27/2022] Open
Abstract
How oocytes are transferred into an oviduct with a receptive environment remains poorly known. We found that glands of the Drosophila female reproductive tract, spermathecae and/or parovaria, are required for ovulation and to promote sperm storage. Reducing total secretory cell number by interferring with Notch signaling during development blocked ovulation. Knocking down expression after adult eclosion of the nuclear hormone receptor Hr39, a master regulator of gland development, slowed ovulation and blocked sperm storage. However, ovulation (but not sperm storage) continued when only canonical protein secretion was compromised in adult glands. Our results imply that proteins secreted during adulthood by the canonical secretory pathway from female reproductive glands are needed to store sperm, while a non-canonical glandular secretion stimulates ovulation. Our results suggest that the reproductive tract signals to the ovary using glandular secretions, and that this pathway has been conserved during evolution. DOI:http://dx.doi.org/10.7554/eLife.00415.001.
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Affiliation(s)
- Jianjun Sun
- Department of Embryology , Carnegie Institution for Science , Baltimore , United States ; Howard Hughes Medical Institute , Baltimore , United States
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Abstract
Mammalian germ cells divide mitotically and form nests of associated cells just prior to entering meiosis. At least some nests contain germline cysts that arise by synchronous, incomplete mitotic divisions, but others may form by aggregation. To systematically investigate early murine germ cell development, we lineage marked the progeny of individual, newly arrived primordial germ cells in the E10.5 gonad. All the marked germ cells initially develop into clones containing two, four or eight cells, indicating cyst formation. Surprisingly, growing cysts in both sexes partially fragment into smaller cysts prior to completion and associate with cysts from unrelated progenitors. At the time divisions cease, female clones comprise five cysts on average that eventually give rise to about six primordial follicles. Male cyst cells break apart and probably become spermatogonial stem cells. Thus, cysts are invariant units of mouse germ cell development and cyst fragmentation provides insight into the amplification of spermatogonial stem cells and the origin of primordial follicles.
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Affiliation(s)
- Lei Lei
- Howard Hughes Medical Institute Research Laboratories, Department of Embryology, Carnegie Institution of Washington, 3520 San Martin Drive, Baltimore, MD 21218, USA
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Sun J, Spradling AC. Female Reproductive Glands Play Essential Roles in Reproduction That May Have Been Conserved During Evolution. Biol Reprod 2012. [DOI: 10.1093/biolreprod/87.s1.347] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Sun J, Spradling AC. NR5A nuclear receptor Hr39 controls three-cell secretory unit formation in Drosophila female reproductive glands. Curr Biol 2012; 22:862-71. [PMID: 22560612 PMCID: PMC3397175 DOI: 10.1016/j.cub.2012.03.059] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2012] [Revised: 03/11/2012] [Accepted: 03/13/2012] [Indexed: 12/31/2022]
Abstract
BACKGROUND Secretions within the adult female reproductive tract mediate sperm survival, storage, activation, and selection. Drosophila female reproductive gland secretory cells reside within the adult spermathecae and parovaria, but their development remains poorly characterized. RESULTS With cell-lineage tracing, we found that precursor cells downregulate lozenge and divide stereotypically to generate three-cell secretory units during pupal development. The NR5A-class nuclear hormone receptor Hr39 is essential for precursor cell division and secretory unit formation. Moreover, ectopic Hr39 in multiple tissues generates reproductive gland-like primordia. Rarely, in male genital discs these primordia can develop into sperm-filled testicular spermathecae. CONCLUSION Drosophila spermathecae provide a powerful model for studying gland development. Hr39 functions as a master regulator of a program that may have been conserved throughout animal evolution for the production of female reproductive glands and other secretory tissues.
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Affiliation(s)
| | - Allan C. Spradling
- Corresponding Author: Dr. Allan C. Spradling, Tel. 410-246-3015, Fax. 410-243-6311,
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36
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Spradling AC. The living-tissue microscope: the importance of studying stem cells in their natural, undisturbed microenvironment. J Pathol 2011; 225:161-2. [DOI: 10.1002/path.2943] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2011] [Revised: 05/18/2011] [Accepted: 05/19/2011] [Indexed: 11/11/2022]
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Morris LX, Spradling AC. Long-term live imaging provides new insight into stem cell regulation and germline-soma coordination in the Drosophila ovary. Development 2011; 138:2207-15. [PMID: 21558370 DOI: 10.1242/dev.065508] [Citation(s) in RCA: 139] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The Drosophila ovariole tip produces new ovarian follicles on a 12-hour cycle by controlling niche-based germline and follicle stem cell divisions and nurturing their developing daughters. Static images provide a thumbnail view of folliculogenesis but imperfectly capture the dynamic cellular interactions that underlie follicle production. We describe a live-imaging culture system that supports normal ovarian stem cell activity, cyst movement and intercellular interaction over 14 hours, which is long enough to visualize all the steps of follicle generation. Our results show that live imaging has unique potential to address diverse aspects of stem cell biology and gametogenesis. Stem cells in cultured tissue respond to insulin and orient their mitotic spindles. Somatic escort cells, the glial-like partners of early germ cells, do not adhere to and migrate along with germline stem cell daughters as previously proposed. Instead, dynamic, microtubule-rich cell membranes pass cysts from one escort cell to the next. Additionally, escort cells are not replenished by the regular division of escort stem cells as previously suggested. Rather, escort cells remain quiescent and divide only to maintain a constant germ cell:escort cell ratio.
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Affiliation(s)
- Lucy X Morris
- Howard Hughes Medical Institute, Department of Embryology, Carnegie Institution, 3520 San Martin Drive, Baltimore, MD 21218, USA
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38
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Abstract
Endopolyploidy arises during normal development in many species when cells undergo endocycles-variant cell cycles in which DNA replicates but daughter cells do not form. Normally, polyploid cells do not divide mitotically after initiating endocycles; hence, little is known about their mitotic competence. However, polyploid cells are found in many tumors, and the enhanced chromosomal instability of polyploid cells in culture suggests that such cells contribute to tumor aneuploidy. Here, we describe a novel polyploid Drosophila cell type that undergoes normal mitotic cycles as part of a remodeling process that forms the adult rectal papillae. Similar polyploid mitotic divisions, but not depolyploidizing divisions, were observed during adult ileum development in the mosquito Culex pipiens. Extended anaphases, chromosome bridges, and lagging chromosomes were frequent during these polyploid divisions, despite normal expression of cell cycle regulators. Our results show that the switch to endocycles during development is not irreversible, but argue that the polyploid mitotic cycle is inherently error-prone, and that polyploid mitoses may help destabilize the cancer genome.
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Affiliation(s)
- Donald T Fox
- Howard Hughes Medical Institute Research Laboratories, Carnegie Institution for Science, Baltimore, Maryland 21218, USA
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39
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Fox DT, Spradling AC. The Drosophila hindgut lacks constitutively active adult stem cells but proliferates in response to tissue damage. Cell Stem Cell 2009; 5:290-7. [PMID: 19699165 PMCID: PMC2772661 DOI: 10.1016/j.stem.2009.06.003] [Citation(s) in RCA: 90] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2009] [Revised: 05/15/2009] [Accepted: 06/05/2009] [Indexed: 12/01/2022]
Abstract
The adult Drosophila hindgut was recently reported to contain active, tissue-replenishing stem cells, like those of the midgut, but located within an anterior ring so as to comprise a single giant crypt. In contrast to this view, we observed no active stem cells and little cell turnover in adult hindgut tissue based on clonal marking and BrdU incorporation studies. Again contradicting the previous proposal, we showed that the adult hindgut is not generated by anterior stem cells during larval/pupal development. However, severe tissue damage within the hindgut elicits cell proliferation within a ring of putative quiescent stem cells at the anterior of the pylorus. Thus, the hindgut does not provide a model of tissue maintenance by constitutively active stem cells, but has great potential to illuminate mechanisms of stress-induced tissue repair.
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Affiliation(s)
- Donald T Fox
- Department of Embryology, Howard Hughes Medical Institute, Carnegie Institution, Baltimore, MD 21218, USA
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40
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Cox RT, Spradling AC. Clueless, a conserved Drosophila gene required for mitochondrial subcellular localization, interacts genetically with parkin. Dis Model Mech 2009; 2:490-9. [PMID: 19638420 PMCID: PMC2737057 DOI: 10.1242/dmm.002378] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Parkinson's disease has been linked to altered mitochondrial function. Mutations in parkin (park), the Drosophila ortholog of a human gene that is responsible for many familial cases of Parkinson's disease, shorten life span, abolish fertility and disrupt mitochondrial structure. However, the role played by Park in mitochondrial function remains unclear. Here, we describe a novel Drosophila gene, clueless (clu), which encodes a highly conserved tetratricopeptide repeat protein that is related closely to the CluA protein of Dictyostelium, Clu1 of Saccharomyces cerevisiae and to similar proteins in diverse metazoan eukaryotes from Arabidopsis to humans. Like its orthologs, loss of Drosophila clu causes mitochondria to cluster within cells. We find that strong clu mutations resemble park mutations in their effects on mitochondrial function and that the two genes interact genetically. Conversely, mitochondria in park homozygotes become highly clustered. We propose that Clu functions in a novel pathway that positions mitochondria within the cell based on their physiological state. Disruption of the Clu pathway may enhance oxidative damage, alter gene expression, cause mitochondria to cluster at microtubule plus ends, and lead eventually to mitochondrial failure.
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Affiliation(s)
- Rachel T Cox
- Department of Embryology/Howard Hughes Medical Institute, Carnegie Institution, 3520 San Martin Drive, Baltimore, MD 21218, USA
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41
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Abstract
Stem cells within diverse tissues share the need for a chromatin configuration that promotes self-renewal, yet few chromatin proteins are known to regulate multiple types of stem cells. We describe a Drosophila gene, scrawny (scny), encoding a ubiquitin-specific protease, which is required in germline, epithelial, and intestinal stem cells. Like its yeast relative UBP10, Scrawny deubiquitylates histone H2B and functions in gene silencing. Consistent with previous studies of this conserved pathway of chromatin regulation, scny mutant cells have elevated levels of ubiquitinylated H2B and trimethylated H3K4. Our findings suggest that inhibiting H2B ubiquitylation through scny represents a common mechanism within stem cells that is used to repress the premature expression of key differentiation genes, including Notch target genes.
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Affiliation(s)
- Michael Buszczak
- Howard Hughes Medical Institute Research Laboratories, Department of Embryology, Carnegie Institution, Baltimore, MD 21218, USA
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42
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Abstract
Niches are local tissue microenvironments that maintain and regulate stem cells. Long-predicted from mammalian studies, these structures have recently been characterized within several invertebrate tissues using methods that reliably identify individual stem cells and their functional requirements. Although similar single-cell resolution has usually not been achieved in mammalian tissues, principles likely to govern the behavior of niches in diverse organisms are emerging. Considerable progress has been made in elucidating how the microenvironment promotes stem cell maintenance. Mechanisms of stem cell maintenance are key to the regulation of homeostasis and likely contribute to aging and tumorigenesis when altered during adulthood.
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Affiliation(s)
- Sean J Morrison
- Howard Hughes Medical Institute, Life Sciences Institute, and Center for Stem Cell Biology, University of Michigan, Ann Arbor, MI, 48109-2216, USA.
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43
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Lighthouse DV, Buszczak M, Spradling AC. New components of the Drosophila fusome suggest it plays novel roles in signaling and transport. Dev Biol 2008; 317:59-71. [PMID: 18355804 PMCID: PMC2410214 DOI: 10.1016/j.ydbio.2008.02.009] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2007] [Accepted: 02/02/2008] [Indexed: 12/18/2022]
Abstract
The fusome plays an essential role in prefollicular germ cell development within insects such as Drosophila melanogaster. Alpha-spectrin and the adducin-like protein Hu-li tai shao (Hts) are required to maintain fusome integrity, synchronize asymmetric cystocyte mitoses, form interconnected 16-cell germline cysts, and specify the initial cell as the oocyte. By screening a library of protein trap lines, we identified 14 new fusome-enriched proteins, including many associated with its characteristic vesicles. Our studies reveal that fusomes change during development and contain recycling endosomal and lysosomal compartments in females but not males. A significant number of fusome components are dispensable, because genetic disruption of tropomodulin, ferritin-1 heavy chain, or scribble, does not alter fusome structure or female fertility. In contrast, rab11 is required to maintain the germline stem cells, and to maintain the vesicle content of the spectrosome, suggesting that the fusome mediates intercellular signals that depend on the recycling endosome.
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Affiliation(s)
- Daniel V Lighthouse
- Howard Hughes Medical Institute Research Laboratories, Department of Embryology, Carnegie Institution, Baltimore, MD 21218, USA
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Abstract
Prostaglandins are local transient hormones that mediate a wide variety of biological events, including reproduction. The study of prostaglandin biology in a genetically tractable invertebrate model organism has been limited by the lack of clearly identified prostaglandin-mediated biological processes and prostaglandin metabolic genes, particularly analogs of cyclooxygenase (COX), the rate-limiting step in vertebrate prostaglandin synthesis. Here, we present pharmacological data that Drosophila ovarian follicle maturation requires COX-like activity and genetic evidence that this activity is supplied in vivo by the Drosophila peroxidase Pxt. pxt mutant females are sterile, and maturing follicles show defects in actin filament formation, nurse cell membrane stability and border cell migration. Maturation of pxt follicles in vitro is stimulated by prostaglandin treatment and fertility is restored in vivo to pxt mutants by expressing mammalian Cox1 protein. Our experiments suggest that prostaglandins promote Drosophila follicle maturation, in part by modulating the actin cytoskeleton, and establish Drosophila oogenesis as a model for understanding these critical biological regulators.
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Affiliation(s)
- Tina L Tootle
- Carnegie Institution, Department of Embryology, Howard Hughes Medical Institute, 3520 San Martin Drive, Baltimore, MD 21218, USA
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Allen AK, Spradling AC. The Sf1-related nuclear hormone receptor Hr39 regulates Drosophila female reproductive tract development and function. Development 2007; 135:311-21. [PMID: 18077584 DOI: 10.1242/dev.015156] [Citation(s) in RCA: 96] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The vertebrate nuclear hormone receptor steroidogenic factor 1 (SF1; NR5A1) controls reproductive development and regulates the transcription of steroid-modifying cytochrome P450 genes. We find that the SF1-related Drosophila nuclear hormone receptor HR39 is also essential for sexual development. In Hr39 mutant females, the sperm-storing spermathecae and glandular parovaria are absent or defective, causing sterility. Our results indicate that spermathecae and parovaria secrete reproductive tract proteins required for sperm maturation and function, like the mammalian epididymis and female reproductive tract. Hr39 controls the expression of specific cytochrome P450 genes and is required in females both to activate spermathecal secretion and repress male-specific courtship genes such as takeout. Thus, a pathway that, in vertebrates, controls sex-specific steroid hormone production, also mediates reproductive functions in an invertebrate. Our findings suggest that Drosophila can be used to model more aspects of mammalian reproductive biology than previously believed.
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Affiliation(s)
- Anna K Allen
- Howard Hughes Medical Institute, Department of Embryology, Carnegie Institution, 3520 San Martin Drive, Baltimore, MD 21218, USA
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Abstract
Drosophila male and female germline stem cells (GSCs) are sustained by niches and regulatory pathways whose common principles serve as models for understanding mammalian stem cells. Despite striking cellular and genetic similarities that suggest a common evolutionary origin, however, male and female GSCs also display important differences. Comparing these two stem cells and their niches in detail is likely to reveal how a common heritage has been adapted to the differing requirements of male and female gamete production.
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Affiliation(s)
- Margaret T Fuller
- Departments of Developmental Biology and Genetics, Stanford University School of Medicine, Stanford, CA 94305, USA
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Affiliation(s)
- Allan C Spradling
- Department of Embryology and Howard Hughes Medical Institute, Carnegie Institution, 3520 San Martin Drive, Baltimore, MD 21218, USA.
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Buszczak M, Paterno S, Lighthouse D, Bachman J, Planck J, Owen S, Skora AD, Nystul TG, Ohlstein B, Allen A, Wilhelm JE, Murphy TD, Levis RW, Matunis E, Srivali N, Hoskins RA, Spradling AC. The carnegie protein trap library: a versatile tool for Drosophila developmental studies. Genetics 2006; 175:1505-31. [PMID: 17194782 PMCID: PMC1840051 DOI: 10.1534/genetics.106.065961] [Citation(s) in RCA: 431] [Impact Index Per Article: 23.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Metazoan physiology depends on intricate patterns of gene expression that remain poorly known. Using transposon mutagenesis in Drosophila, we constructed a library of 7404 protein trap and enhancer trap lines, the Carnegie collection, to facilitate gene expression mapping at single-cell resolution. By sequencing the genomic insertion sites, determining splicing patterns downstream of the enhanced green fluorescent protein (EGFP) exon, and analyzing expression patterns in the ovary and salivary gland, we found that 600-900 different genes are trapped in our collection. A core set of 244 lines trapped different identifiable protein isoforms, while insertions likely to act as GFP-enhancer traps were found in 256 additional genes. At least 8 novel genes were also identified. Our results demonstrate that the Carnegie collection will be useful as a discovery tool in diverse areas of cell and developmental biology and suggest new strategies for greatly increasing the coverage of the Drosophila proteome with protein trap insertions.
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Affiliation(s)
- Michael Buszczak
- Howard Hughes Medical Institute Research Laboratories, Department of Embryology, Carnegie Institution of Washington, Baltimore, Maryland 21218, USA
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Pepling ME, Wilhelm JE, O'Hara AL, Gephardt GW, Spradling AC. Mouse oocytes within germ cell cysts and primordial follicles contain a Balbiani body. Proc Natl Acad Sci U S A 2006; 104:187-92. [PMID: 17189423 PMCID: PMC1765432 DOI: 10.1073/pnas.0609923104] [Citation(s) in RCA: 173] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
The Balbiani body or mitochondrial cloud is a large distinctive organelle aggregate found in developing oocytes of many species, but its presence in the mouse has been controversial. Using confocal and electron microscopy, we report that a Balbiani body does arise in mouse neonatal germline cysts and oocytes of primordial follicles but disperses as follicles begin to grow. The mouse Balbiani body contains a core of Golgi elements surrounded by mitochondria and associated endoplasmic reticulum. Because of their stage specificity and perinuclear rather than spherical distribution, these clustered Balbiani body mitochondria may have been missed previously. The Balbiani body also contains Trailer hitch, a widely conserved member of a protein complex that associates with endoplasmic reticulum/Golgi-like vesicles and transports specific RNAs during Drosophila oogenesis. Our results provide evidence that mouse oocytes develop using molecular and developmental mechanisms widely conserved throughout the animal kingdom.
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Affiliation(s)
- Melissa E. Pepling
- *Department of Biology, Syracuse University, Syracuse, NY 13244; and
- To whom correspondence may be addressed. E-mail:
or
| | - James E. Wilhelm
- Department of Embryology/Howard Hughes Medical Institute, Carnegie Institution of Washington, Baltimore, MD 21210
| | - Ashley L. O'Hara
- *Department of Biology, Syracuse University, Syracuse, NY 13244; and
| | - Grant W. Gephardt
- *Department of Biology, Syracuse University, Syracuse, NY 13244; and
| | - Allan C. Spradling
- Department of Embryology/Howard Hughes Medical Institute, Carnegie Institution of Washington, Baltimore, MD 21210
- To whom correspondence may be addressed. E-mail:
or
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Affiliation(s)
- Allan C Spradling
- Department of Embryology, Carnegie Institution of Washington/HHMI, Baltimore, MD 21218, USA.
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