1
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Jackson JA, Denk-Lobnig M, Kitzinger KA, Martin AC. Change in RhoGAP and RhoGEF availability drives transitions in cortical patterning and excitability in Drosophila. Curr Biol 2024; 34:2132-2146.e5. [PMID: 38688282 PMCID: PMC11111359 DOI: 10.1016/j.cub.2024.04.021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2023] [Revised: 02/13/2024] [Accepted: 04/09/2024] [Indexed: 05/02/2024]
Abstract
Actin cortex patterning and dynamics are critical for cell shape changes. These dynamics undergo transitions during development, often accompanying changes in collective cell behavior. Although mechanisms have been established for individual cells' dynamic behaviors, the mechanisms and specific molecules that result in developmental transitions in vivo are still poorly understood. Here, we took advantage of two developmental systems in Drosophila melanogaster to identify conditions that altered cortical patterning and dynamics. We identified a Rho guanine nucleotide exchange factor (RhoGEF) and Rho GTPase activating protein (RhoGAP) pair required for actomyosin waves in egg chambers. Specifically, depletion of the RhoGEF, Ect2, or the RhoGAP, RhoGAP15B, disrupted actomyosin wave induction, and both proteins relocalized from the nucleus to the cortex preceding wave formation. Furthermore, we found that overexpression of a different RhoGEF and RhoGAP pair, RhoGEF2 and Cumberland GAP (C-GAP), resulted in actomyosin waves in the early embryo, during which RhoA activation precedes actomyosin assembly by ∼4 s. We found that C-GAP was recruited to actomyosin waves, and disrupting F-actin polymerization altered the spatial organization of both RhoA signaling and the cytoskeleton in waves. In addition, disrupting F-actin dynamics increased wave period and width, consistent with a possible role for F-actin in promoting delayed negative feedback. Overall, we showed a mechanism involved in inducing actomyosin waves that is essential for oocyte development and is general to other cell types, such as epithelial and syncytial cells.
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Affiliation(s)
- Jonathan A Jackson
- Department of Biology, Massachusetts Institute of Technology, 77 Massachusetts Ave., Cambridge, MA 02139, USA; Graduate Program in Biophysics, Harvard University, 86 Brattle Street, Cambridge, MA 02138, USA
| | - Marlis Denk-Lobnig
- Department of Biophysics, University of Michigan, 1109 Geddes Ave., Ann Arbor, MI 48109, USA
| | - Katherine A Kitzinger
- Department of Biology, Massachusetts Institute of Technology, 77 Massachusetts Ave., Cambridge, MA 02139, USA
| | - Adam C Martin
- Department of Biology, Massachusetts Institute of Technology, 77 Massachusetts Ave., Cambridge, MA 02139, USA.
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2
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Gilliland WD, May DP, Bowen AO, Conger KO, Elrad D, Marciniak M, Mashburn SA, Presbitero G, Welk LF. A cytological F1 RNAi screen for defects in Drosophila melanogaster female meiosis. Genetics 2024; 227:iyae046. [PMID: 38531678 DOI: 10.1093/genetics/iyae046] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2024] [Revised: 01/11/2024] [Accepted: 03/16/2024] [Indexed: 03/28/2024] Open
Abstract
Genetic screens for recessive alleles induce mutations, make the mutated chromosomes homozygous, and then assay those homozygotes for the phenotype of interest. When screening for genes required for female meiosis, the phenotype of interest has typically been nondisjunction from chromosome segregation errors. As this requires that mutant females be viable and fertile, any mutants that are lethal or sterile when homozygous cannot be recovered by this approach. To overcome these limitations, we have screened the VALIUM22 collection of RNAi constructs that target germline-expressing genes in a vector optimized for germline expression by driving RNAi with GAL4 under control of a germline-specific promoter (nanos or mat-alpha4). This allowed us to test genes that would be lethal if knocked down in all cells, and by examining unfertilized metaphase-arrested mature oocytes, we could identify defects in sterile females. After screening >1,450 lines of the collection for two different defects (chromosome congression and the hypoxic sequestration of Mps1-GFP to ooplasmic filaments), we obtained multiple hits for both phenotypes, identified novel meiotic phenotypes for genes that had been previously characterized in other processes, and identified the first phenotypes to be associated with several previously uncharacterized genes.
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Affiliation(s)
- William D Gilliland
- Department of Biological Sciences, DePaul University, Chicago, IL 60614, USA
| | - Dennis P May
- Department of Biological Sciences, DePaul University, Chicago, IL 60614, USA
| | - Amelia O Bowen
- Department of Biological Sciences, DePaul University, Chicago, IL 60614, USA
| | - Kelly O Conger
- Department of Biological Sciences, DePaul University, Chicago, IL 60614, USA
| | - Doreen Elrad
- Department of Biological Sciences, DePaul University, Chicago, IL 60614, USA
| | - Marcin Marciniak
- Department of Biological Sciences, DePaul University, Chicago, IL 60614, USA
| | - Sarah A Mashburn
- Department of Biological Sciences, DePaul University, Chicago, IL 60614, USA
| | | | - Lucas F Welk
- Department of Biological Sciences, DePaul University, Chicago, IL 60614, USA
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3
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Gomez A, Gonzalez S, Oke A, Luo J, Duong JB, Esquerra RM, Zimmerman T, Capponi S, Fung JC, Nystul TG. A high-throughput method for quantifying Drosophila fecundity. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.03.27.587093. [PMID: 38585877 PMCID: PMC10996622 DOI: 10.1101/2024.03.27.587093] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/09/2024]
Abstract
Measurements of Drosophila fecundity are used in a wide variety of studies, such as investigations of stem cell biology, nutrition, behavior, and toxicology. In addition, because fecundity assays are performed on live flies, they are suitable for longitudinal studies such as investigations of aging or prolonged chemical exposure. However, standard Drosophila fecundity assays have been difficult to perform in a high-throughput manner because experimental factors such as the physiological state of the flies and environmental cues must be carefully controlled to achieve consistent results. In addition, exposing flies to a large number of different experimental conditions (such as chemical additives in the diet) and manually counting the number of eggs laid to determine the impact on fecundity is time-consuming. We have overcome these challenges by combining a new multiwell fly culture strategy with a novel 3D-printed fly transfer device to rapidly and accurately transfer flies from one plate to another; the RoboCam, a low-cost, custom built robotic camera to capture images of the wells automatically; and an image segmentation pipeline to automatically identify and quantify eggs. We show that this method is compatible with robust and consistent egg laying throughout the assay period; and demonstrate that the automated pipeline for quantifying fecundity is very accurate (r2 = 0.98 for the correlation between the automated egg counts and the ground truth) In addition, we show that this method can be used to efficiently detect the effects on fecundity induced by dietary exposure to chemicals. Taken together, this strategy substantially increases the efficiency and reproducibility of high throughput egg laying assays that require exposing flies to multiple different media conditions.
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Affiliation(s)
- Andreana Gomez
- University of California, San Francisco, Department of Anatomy
| | - Sergio Gonzalez
- San Francisco State University, Department of Biology
- Center for Cellular Construction, San Francisco, CA
| | - Ashwini Oke
- San Francisco State University, Department of Chemistry and Biochemistry; University of California, San Francisco, OB/GYN Department
- IBM Almaden Research Center, San Jose, CA; University of California, San Francisco, Center for Reproductive Sciences
| | - Jiayu Luo
- San Francisco State University, Department of Biology
- Center for Cellular Construction, San Francisco, CA
| | - Johnny B Duong
- Center for Cellular Construction, San Francisco, CA
- San Francisco State University, Department of Chemistry and Biochemistry; University of California, San Francisco, OB/GYN Department
| | - Raymond M Esquerra
- Center for Cellular Construction, San Francisco, CA
- San Francisco State University, Department of Chemistry and Biochemistry; University of California, San Francisco, OB/GYN Department
| | - Thomas Zimmerman
- Center for Cellular Construction, San Francisco, CA
- IBM Almaden Research Center, San Jose, CA; University of California, San Francisco, Center for Reproductive Sciences
| | - Sara Capponi
- Center for Cellular Construction, San Francisco, CA
- IBM Almaden Research Center, San Jose, CA; University of California, San Francisco, Center for Reproductive Sciences
| | - Jennifer C Fung
- San Francisco State University, Department of Chemistry and Biochemistry; University of California, San Francisco, OB/GYN Department
- IBM Almaden Research Center, San Jose, CA; University of California, San Francisco, Center for Reproductive Sciences
- University of California, San Francisco EaRTH Center
| | - Todd G Nystul
- University of California, San Francisco, Department of Anatomy
- San Francisco State University, Department of Chemistry and Biochemistry; University of California, San Francisco, OB/GYN Department
- IBM Almaden Research Center, San Jose, CA; University of California, San Francisco, Center for Reproductive Sciences
- University of California, San Francisco EaRTH Center
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4
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Gilliland WD, May DP, Bowen AO, Conger KO, Elrad D, Marciniak M, Mashburn SA, Presbitero G, Welk LF. A Cytological F1 RNAi Screen for Defects in Drosophila melanogaster Female Meiosis. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.01.12.575435. [PMID: 38293152 PMCID: PMC10827134 DOI: 10.1101/2024.01.12.575435] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2024]
Abstract
Genetic screens for recessive alleles induce mutations, make the mutated chromosomes homozygous, and then assay those homozygotes for the phenotype of interest. When screening for genes required for female meiosis, the phenotype of interest has typically been nondisjunction from chromosome segregation errors. As this requires that mutant females be viable and fertile, any mutants that are lethal or sterile when homozygous cannot be recovered by this approach. To overcome these limitations, our lab has screened the VALIUM22 collection produced by the Harvard TRiP Project, which contains RNAi constructs targeting genes known to be expressed in the germline in a vector optimized for germline expression. By driving RNAi with GAL4 under control of a germline-specific promoter (nanos or mat-alpha4), we can test genes that would be lethal if knocked down in all cells, and by examining unfertilized metaphase-arrested mature oocytes, we can identify defects associated with genes whose knockdown results in sterility or causes other errors besides nondisjunction. We screened this collection to identify genes that disrupt either of two phenotypes when knocked down: the ability of meiotic chromosomes to congress to a single mass at the end of prometaphase, and the sequestration of Mps1-GFP to ooplasmic filaments in response to hypoxia. After screening >1450 lines of the collection, we obtained multiple hits for both phenotypes, identified novel meiotic phenotypes for genes that had been previously characterized in other processes, and identified the first phenotypes to be associated with several previously uncharacterized genes.
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Affiliation(s)
| | | | | | | | - Doreen Elrad
- DePaul University Department of Biological Sciences
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5
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Nishida H, Albero AB, Onoue K, Ikegawa Y, Sulekh S, Sakizli U, Minami Y, Yonemura S, Wang YC, Yoo SK. Necrosensor: a genetically encoded fluorescent sensor for visualizing necrosis in Drosophila. Biol Open 2024; 13:bio060104. [PMID: 38156558 PMCID: PMC10836653 DOI: 10.1242/bio.060104] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2023] [Accepted: 12/15/2023] [Indexed: 12/30/2023] Open
Abstract
Historically, necrosis has been considered a passive process, which is induced by extreme stress or damage. However, recent findings of necroptosis, a programmed form of necrosis, shed a new light on necrosis. It has been challenging to detect necrosis reliably in vivo, partly due to the lack of genetically encoded sensors to detect necrosis. This is in stark contrast with the availability of many genetically encoded biosensors for apoptosis. Here we developed Necrosensor, a genetically encoded fluorescent sensor that detects necrosis in Drosophila, by utilizing HMGB1, which is released from the nucleus as a damage-associated molecular pattern (DAMP). We demonstrate that Necrosensor is able to detect necrosis induced by various stresses in multiple tissues in both live and fixed conditions. Necrosensor also detects physiological necrosis that occurs during spermatogenesis in the testis. Using Necrosensor, we discovered previously unidentified, physiological necrosis of hemocyte progenitors in the hematopoietic lymph gland of developing larvae. This work provides a new transgenic system that enables in vivo detection of necrosis in real time without any intervention.
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Affiliation(s)
- Hiroshi Nishida
- Division of Cell Physiology, Graduate School of Medicine, Kobe University, Kobe, 650-0017, Japan
- Physiological Genetics Laboratory, RIKEN CPR, Kobe, 650-0047, Japan
| | | | - Kenta Onoue
- Laboratory for Ultrastructural Research, RIKEN BDR, Kobe, 650-0047, Japan
| | - Yuko Ikegawa
- Laboratory of Molecular Cell Biology and Development, Kyoto University, Kobe, 650-0047, Japan
- Laboratory for Homeodynamics, RIKEN BDR, Kobe, 650-0047, Japan
| | - Shivakshi Sulekh
- Laboratory for Homeodynamics, RIKEN BDR, Kobe, 650-0047, Japan
- Division of Developmental Biology and Regenerative Medicine, Graduate School of Medicine, Kobe University, Kobe, 650-0047, Japan
| | - Ugurcan Sakizli
- Laboratory for Homeodynamics, RIKEN BDR, Kobe, 650-0047, Japan
- Division of Developmental Biology and Regenerative Medicine, Graduate School of Medicine, Kobe University, Kobe, 650-0047, Japan
| | - Yasuhiro Minami
- Division of Cell Physiology, Graduate School of Medicine, Kobe University, Kobe, 650-0017, Japan
| | - Shigenobu Yonemura
- Laboratory for Ultrastructural Research, RIKEN BDR, Kobe, 650-0047, Japan
- Department of Cell Biology, Tokushima University Graduate School of Medicine, Tokushima, 770-8503, Japan
| | - Yu-Chiun Wang
- Laboratory for Epithelial Morphogenesis, RIKEN BDR, Kobe, 650-0047, Japan
| | - Sa Kan Yoo
- Physiological Genetics Laboratory, RIKEN CPR, Kobe, 650-0047, Japan
- Laboratory for Homeodynamics, RIKEN BDR, Kobe, 650-0047, Japan
- Division of Developmental Biology and Regenerative Medicine, Graduate School of Medicine, Kobe University, Kobe, 650-0047, Japan
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6
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Li L, Zhang N, Beati SAH, De Las Heras Chanes J, di Pietro F, Bellaiche Y, Müller HAJ, Großhans J. Kinesin-1 patterns Par-1 and Rho signaling at the cortex of syncytial embryos of Drosophila. J Cell Biol 2024; 223:e202206013. [PMID: 37955925 PMCID: PMC10641515 DOI: 10.1083/jcb.202206013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2022] [Revised: 03/23/2023] [Accepted: 10/18/2023] [Indexed: 11/14/2023] Open
Abstract
The cell cortex of syncytial Drosophila embryos is patterned into cap and intercap regions by centrosomes, specific sets of proteins that are restricted to their respective regions by unknown mechanisms. Here, we found that Kinesin-1 is required for the restriction of plus- and minus-ends of centrosomal and non-centrosomal microtubules to the cap region, marked by EB1 and Patronin/Shot, respectively. Kinesin-1 also directly or indirectly restricts proteins and Rho signaling to the intercap, including the RhoGEF Pebble, Dia, Myosin II, Capping protein-α, and the polarity protein Par-1. Furthermore, we found that Par-1 is required for cap restriction of Patronin/Shot, and vice versa Patronin, for Par-1 enrichment at the intercap. In summary, our data support a model that Kinesin-1 would mediate the restriction of centrosomal and non-centrosomal microtubules to a region close to the centrosomes and exclude Rho signaling and Par-1. In addition, mutual antagonistic interactions would refine and maintain the boundary between cap and intercap and thus generate a distinct cortical pattern.
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Affiliation(s)
- Long Li
- Department of Biology, Philipps University, Marburg, Germany
| | - Na Zhang
- Department of Biology, Philipps University, Marburg, Germany
| | - Seyed Amir Hamze Beati
- Division of Developmental Genetics, Institute for Biology, University of Kassel, Kassel, Germany
| | - Jose De Las Heras Chanes
- Institut Curie, Université PSL, Sorbonne Université, CNRS UMR 3215, Inserm U934, Genetics and Developmental Biology , Paris, France
| | - Florencia di Pietro
- Institut Curie, Université PSL, Sorbonne Université, CNRS UMR 3215, Inserm U934, Genetics and Developmental Biology , Paris, France
| | - Yohanns Bellaiche
- Institut Curie, Université PSL, Sorbonne Université, CNRS UMR 3215, Inserm U934, Genetics and Developmental Biology , Paris, France
| | - Hans-Arno J Müller
- Division of Developmental Genetics, Institute for Biology, University of Kassel, Kassel, Germany
| | - Jörg Großhans
- Department of Biology, Philipps University, Marburg, Germany
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7
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Cortez CT, Murphy RO, Owens IM, Beckmann JF. Use of Drosophila Transgenics to Identify Functions for Symbiont Effectors. Methods Mol Biol 2024; 2739:301-320. [PMID: 38006559 DOI: 10.1007/978-1-0716-3553-7_18] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2023]
Abstract
Wolbachia, one of the most successful and studied insect symbionts, and Drosophila, one of the most understood model insects, can be exploited as complementary tools to unravel mechanisms of insect symbiosis. Although Wolbachia itself cannot be grown axenically as clonal isolates or genetically manipulated by standard methods, its reproductive phenotypes, including cytoplasmic incompatibility (CI), have been elucidated using well-developed molecular tools and precise transgenic manipulations available for Drosophila melanogaster. Current research only scratches the surface of how Drosophila can provide a tool for understanding Wolbachia's evolutionary success and the molecular roles of its genetic elements. Here, we briefly outline basic methodologies inherent to transgenic Drosophila systems that have already contributed significant advances in understanding CI, but may be unfamiliar to those who lack experience in Drosophila genetics. In the future, these approaches will continue providing significant insights into Wolbachia that undoubtedly will be extended to other insect symbionts and their biological capabilities.
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Affiliation(s)
- Carai T Cortez
- Department of Entomology and Plant Pathology, Auburn University, Auburn, AL, USA
| | - Richard O Murphy
- Department of Entomology and Plant Pathology, Auburn University, Auburn, AL, USA
| | - Isabella M Owens
- Department of Entomology and Plant Pathology, Auburn University, Auburn, AL, USA
| | - John F Beckmann
- Department of Entomology and Plant Pathology, Auburn University, Auburn, AL, USA.
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8
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Jackson JA, Denk-Lobnig M, Kitzinger KA, Martin AC. Change in RhoGAP and RhoGEF availability drives transitions in cortical patterning and excitability in Drosophila. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.11.06.565883. [PMID: 37986763 PMCID: PMC10659369 DOI: 10.1101/2023.11.06.565883] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2023]
Abstract
Actin cortex patterning and dynamics are critical for cell shape changes. These dynamics undergo transitions during development, often accompanying changes in collective cell behavior. While mechanisms have been established for individual cells' dynamic behaviors, mechanisms and specific molecules that result in developmental transitions in vivo are still poorly understood. Here, we took advantage of two developmental systems in Drosophila melanogaster to identify conditions that altered cortical patterning and dynamics. We identified a RhoGEF and RhoGAP pair whose relocalization from nucleus to cortex results in actomyosin waves in egg chambers. Furthermore, we found that overexpression of a different RhoGEF and RhoGAP pair resulted in actomyosin waves in the early embryo, during which RhoA activation precedes actomyosin assembly and RhoGAP recruitment by ~4 seconds. Overall, we showed a mechanism involved in inducing actomyosin waves that is essential for oocyte development and is general to other cell types.
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Affiliation(s)
- Jonathan A. Jackson
- Department of Biology, Massachusetts Institute of Technology
- Graduate Program in Biophysics, Harvard University
| | | | | | - Adam C. Martin
- Department of Biology, Massachusetts Institute of Technology
- Lead contact
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9
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Zajac AL, Williams AM, Horne-Badovinac S. A Low-Tech Flow Chamber for Live Imaging of Drosophila Egg Chambers During Drug Treatments. Methods Mol Biol 2023; 2626:277-289. [PMID: 36715910 DOI: 10.1007/978-1-0716-2970-3_14] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The Drosophila egg chamber is a powerful system to study epithelial cell collective migration and polarized basement membrane secretion. A strength of this system is the ability to capture these dynamic processes in ex vivo organ culture using high-resolution live imaging. Ex vivo culture also allows acute pharmacological or labeling treatments, extending the versatility of the system. However, many current ex vivo egg chamber culture setups do not permit easy medium exchange, preventing researchers from following individual egg chambers through multiple treatments. Here we present a method to immobilize egg chambers in an easy-to-construct flow chamber that permits imaging of the same egg chamber through repeated solution exchanges. This will allow researchers to take greater advantage of the wide variety of available pharmacological perturbations and other treatments like dyes to study dynamic processes in the egg chamber.
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Affiliation(s)
- Allison L Zajac
- Department of Molecular Genetics and Cell Biology, The University of Chicago, Chicago, IL, USA
| | - Audrey Miller Williams
- Department of Molecular Genetics and Cell Biology, The University of Chicago, Chicago, IL, USA
| | - Sally Horne-Badovinac
- Department of Molecular Genetics and Cell Biology, The University of Chicago, Chicago, IL, USA.
- Committee on Development, Regeneration, and Stem Cell Biology, The University of Chicago, Chicago, IL, USA.
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10
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Optimized Fixation and Phalloidin Staining of Basally Localized F-Actin Networks in Collectively Migrating Follicle Cells. Methods Mol Biol 2023; 2626:179-191. [PMID: 36715905 DOI: 10.1007/978-1-0716-2970-3_9] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The follicular epithelial cells of the Drosophila egg chamber have become a premier model to study how cells globally orient their actin-based machinery for collective migration. The basal surface of each follicle cell has lamellipodial and filopodial protrusions that extend from its leading edge and an array of stress fibers that mediate its adhesion to the extracellular matrix; these migratory structures are all globally aligned in the direction of tissue movement. To understand how this global alignment is achieved, one must be able to reliably visualize the underlying F-actin; however, dynamic F-actin networks can be difficult to preserve in fixed tissues. Here, we describe an optimized protocol for the fixation and phalloidin staining of the follicular epithelium. We also provide a brief primer on relevant aspects of the image acquisition process to ensure high quality data are collected.
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11
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Serizier SB, Peterson JS, McCall K. Non-autonomous cell death induced by the Draper phagocytosis receptor requires signaling through the JNK and SRC pathways. J Cell Sci 2022; 135:jcs250134. [PMID: 36177600 PMCID: PMC10658789 DOI: 10.1242/jcs.250134] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2020] [Accepted: 09/21/2022] [Indexed: 11/20/2022] Open
Abstract
The last step of cell death is cell clearance, a process critical for tissue homeostasis. For efficient cell clearance to occur, phagocytes and dead cells need to reciprocally signal to each other. One important phenomenon that is under-investigated, however, is that phagocytes not only engulf corpses but contribute to cell death progression. The aims of this study were to determine how the phagocytic receptor Draper non-autonomously induces cell death, using the Drosophila ovary as a model system. We found that Draper, expressed in epithelial follicle cells, requires its intracellular signaling domain to kill the adjacent nurse cell population. Kinases Src42A, Shark and JNK (Bsk) were required for Draper-induced nurse cell death. Signs of nurse cell death occurred prior to apparent engulfment and required the caspase Dcp-1, indicating that it uses a similar apoptotic pathway to starvation-induced cell death. These findings indicate that active signaling by Draper is required to kill nurse cells via the caspase Dcp-1, providing novel insights into mechanisms of phagoptosis driven by non-professional phagocytes.
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Affiliation(s)
- Sandy B. Serizier
- Department of Biology, Boston University, 5 Cummington Mall, Boston, MA 02215, USA
- Program in Molecular Biology, Cell Biology, and Biochemistry, Boston University, 5 Cummington Mall, Boston, MA 02215, USA
| | - Jeanne S. Peterson
- Department of Biology, Boston University, 5 Cummington Mall, Boston, MA 02215, USA
| | - Kimberly McCall
- Department of Biology, Boston University, 5 Cummington Mall, Boston, MA 02215, USA
- Program in Molecular Biology, Cell Biology, and Biochemistry, Boston University, 5 Cummington Mall, Boston, MA 02215, USA
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12
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Restriction of subapical proteins during cellularization depends on the onset of zygotic transcription and the formin Dia. Dev Biol 2022; 487:110-121. [PMID: 35525304 DOI: 10.1016/j.ydbio.2022.04.012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2021] [Revised: 04/25/2022] [Accepted: 04/28/2022] [Indexed: 11/21/2022]
Abstract
Cortical domains are characterized by spatially restricted polarity proteins. The pattern of cortical domains is dynamic and changes during cell differentiation and development. Although there is a good understanding for how the cortical pattern is maintained, e. g. by mutual antagonism, less is known about how the initial pattern is established, and its dynamics coordinated with developmental progression. Here we investigate the initial restriction of subapical marker proteins during the syncytial-cellular transition in Drosophila embryos. The subapical markers Canoe/Afadin, the complex ELMO-Sponge, Baz and Arm become initially restricted between apical and lateral domains during cellularization. We define the role of zygotic genome activation as a timer for subapical domain formation. Subapical markers remained widely spread in embryos treated with α-amanitin and became precociously restricted in mutant embryos with premature zygotic transcription. In contrast, remodeling of the nuclear division cycle without cytokinesis to a full cell cycle is not a prerequisite for subapical domain formation, since we observed timely subapical restriction in embryos undergoing an extra nuclear cycle. We provide evidence that earliest subapical markers ELMO-Sponge and Canoe are required for subapical accumulation of Baz. Supporting an important role of cortical F-actin in subapical restriction, we found that the formin Dia was required for Baz restriction, and its distribution depended on the onset of zygotic gene expression. In summary, we define zygotic transcription as a timer, to which subapical markers respond in a dia-dependent mechanism.
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13
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Li Y, Bagheri P, Chang P, Zeng A, Hao J, Fung A, Wu JY, Shi L. Direct Imaging of Lipid Metabolic Changes in Drosophila Ovary During Aging Using DO-SRS Microscopy. FRONTIERS IN AGING 2022; 2:819903. [PMID: 35822015 PMCID: PMC9261447 DOI: 10.3389/fragi.2021.819903] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/22/2021] [Accepted: 12/29/2021] [Indexed: 01/09/2023]
Abstract
Emerging studies have shown that lipids and proteins play versatile roles in various aspects of aging. High-resolution in situ optical imaging provides a powerful approach to study the metabolic dynamics of lipids and proteins during aging. Here, we integrated D2O probing and stimulated Raman scattering (DO-SRS) microscopy to directly visualize metabolic changes in aging Drosophila ovary. The subcellular spatial distribution of de novo protein synthesis and lipogenesis in ovary was quantitatively imaged and examined. Our Raman spectra showed that early stages follicles were protein-enriched whereas mature eggs were lipid-enriched. DO-SRS imaging showed a higher protein synthesis in the earlier developing stages and an increased lipid turned over at the late stage. Aged (35 days) flies exhibited a dramatic decrease in metabolic turnover activities of both proteins and lipids, particularly, in the germ stem cell niche of germarium. We found an accumulation of unsaturated lipids in the nurse cells and oocytes in old flies, suggesting that unsaturated lipids may play an important role in the processes of oocyte maturation. We further detected changes in mitochondrial morphology and accumulation of Cytochrome c during aging. To our knowledge, this is the first study that directly visualizes spatiotemporal changes in lipid and protein metabolism in Drosophila ovary during development and aging processes. Our study not only demonstrates the application of a new imaging platform in visualizing metabolic dynamics of lipids and proteins in situ but also unravels how the metabolic activity and lipid distribution change in Drosophila ovary during aging.
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Affiliation(s)
- Yajuan Li
- The Department of Bioengineering, University of California San Diego, La Jolla, CA, United States
| | - Pegah Bagheri
- The Department of Bioengineering, University of California San Diego, La Jolla, CA, United States
| | - Phyllis Chang
- The Department of Bioengineering, University of California San Diego, La Jolla, CA, United States
| | - Audrey Zeng
- The Department of Bioengineering, University of California San Diego, La Jolla, CA, United States
| | - Jie Hao
- The Department of Bioengineering, University of California San Diego, La Jolla, CA, United States
| | - Anthony Fung
- The Department of Bioengineering, University of California San Diego, La Jolla, CA, United States
| | - Jane Y. Wu
- Department of Neurology, Northwestern University, Chicago, IL, United States
| | - Lingyan Shi
- The Department of Bioengineering, University of California San Diego, La Jolla, CA, United States
- *Correspondence: Lingyan Shi,
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14
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Russell SA, Laws KM, Bashaw GJ. Frazzled/Dcc acts independently of Netrin to promote germline survival during Drosophila oogenesis. Development 2021; 148:dev199762. [PMID: 34910816 PMCID: PMC8722396 DOI: 10.1242/dev.199762] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2021] [Accepted: 11/16/2021] [Indexed: 11/20/2022]
Abstract
The Netrin receptor Frazzled/Dcc (Fra in Drosophila) functions in diverse tissue contexts to regulate cell migration, axon guidance and cell survival. Fra signals in response to Netrin to regulate the cytoskeleton and also acts independently of Netrin to directly regulate transcription during axon guidance in Drosophila. In other contexts, Dcc acts as a tumor suppressor by directly promoting apoptosis. In this study, we report that Fra is required in the Drosophila female germline for the progression of egg chambers through mid-oogenesis. Loss of Fra in the germline, but not the somatic cells of the ovary, results in the degeneration of egg chambers. Although a failure in nutrient sensing and disruptions in egg chamber polarity can result in degeneration at mid-oogenesis, these factors do not appear to be affected in fra germline mutants. However, similar to the degeneration that occurs in those contexts, the cell death effector Dcp-1 is activated in fra germline mutants. The function of Fra in the female germline is independent of Netrin and requires the transcriptional activation domain of Fra. In contrast to the role of Dcc in promoting cell death, our observations reveal a role for Fra in regulating germline survival by inhibiting apoptosis.
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Affiliation(s)
| | - Kaitlin M. Laws
- Department of Neuroscience, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Greg J. Bashaw
- Department of Neuroscience, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
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15
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Lebo DPV, Chirn A, Taylor JD, Levan A, Doerre Torres V, Agreda E, Serizier SB, Lord AK, Jenkins VK, McCall K. An RNAi screen of the kinome in epithelial follicle cells of the Drosophila melanogaster ovary reveals genes required for proper germline death and clearance. G3-GENES GENOMES GENETICS 2021; 11:6080751. [PMID: 33693600 PMCID: PMC8022946 DOI: 10.1093/g3journal/jkaa066] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/27/2019] [Accepted: 12/09/2020] [Indexed: 02/07/2023]
Abstract
Programmed cell death and cell corpse clearance are an essential part of organismal health and development. Cell corpses are often cleared away by professional phagocytes such as macrophages. However, in certain tissues, neighboring cells known as nonprofessional phagocytes can also carry out clearance functions. Here, we use the Drosophila melanogaster ovary to identify novel genes required for clearance by nonprofessional phagocytes. In the Drosophila ovary, germline cells can die at multiple time points. As death proceeds, the epithelial follicle cells act as phagocytes to facilitate the clearance of these cells. We performed an unbiased kinase screen to identify novel proteins and pathways involved in cell clearance during two death events. Of 224 genes examined, 18 demonstrated severe phenotypes during developmental death and clearance while 12 demonstrated severe phenotypes during starvation-induced cell death and clearance, representing a number of pathways not previously implicated in phagocytosis. Interestingly, it was found that several genes not only affected the clearance process in the phagocytes, but also non-autonomously affected the process by which germline cells died. This kinase screen has revealed new avenues for further exploration and investigation.
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Affiliation(s)
- Diane P V Lebo
- Department of Biology, Boston University, Boston, MA 02215, USA
| | - Alice Chirn
- Department of Biology, Boston University, Boston, MA 02215, USA
| | - Jeffrey D Taylor
- Department of Biology, Boston University, Boston, MA 02215, USA.,Program in Biochemistry and Molecular Biology, Boston University, Boston, MA 02215, USA
| | - Andre Levan
- Department of Biology, Boston University, Boston, MA 02215, USA.,Program in Biochemistry and Molecular Biology, Boston University, Boston, MA 02215, USA
| | | | - Emily Agreda
- Department of Biology, Boston University, Boston, MA 02215, USA
| | - Sandy B Serizier
- Department of Biology, Boston University, Boston, MA 02215, USA.,Program in Molecular Biology, Cell Biology, and Biochemistry, Boston University, Boston, MA 02215, USA
| | - Allison K Lord
- Department of Biology, Boston University, Boston, MA 02215, USA
| | | | - Kimberly McCall
- Department of Biology, Boston University, Boston, MA 02215, USA
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16
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Lebo DPV, McCall K. Murder on the Ovarian Express: A Tale of Non-Autonomous Cell Death in the Drosophila Ovary. Cells 2021; 10:cells10061454. [PMID: 34200604 PMCID: PMC8228772 DOI: 10.3390/cells10061454] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2021] [Revised: 06/05/2021] [Accepted: 06/07/2021] [Indexed: 12/30/2022] Open
Abstract
Throughout oogenesis, Drosophila egg chambers traverse the fine line between survival and death. After surviving the ten early and middle stages of oogenesis, egg chambers drastically change their size and structure to produce fully developed oocytes. The development of an oocyte comes at a cost, the price is the lives of the oocyte’s 15 siblings, the nurse cells. These nurse cells do not die of their own accord. Their death is dependent upon their neighbors—the stretch follicle cells. Stretch follicle cells are nonprofessional phagocytes that spend the final stages of oogenesis surrounding the nurse cells and subsequently forcing the nurse cells to give up everything for the sake of the oocyte. In this review, we provide an overview of cell death in the ovary, with a focus on recent findings concerning this phagocyte-dependent non-autonomous cell death.
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17
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RNAi-based screens uncover a potential new role for the orphan neuropeptide receptor Moody in Drosophila female germline stem cell maintenance. PLoS One 2020; 15:e0243756. [PMID: 33307547 PMCID: PMC7732368 DOI: 10.1371/journal.pone.0243756] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2020] [Accepted: 11/25/2020] [Indexed: 01/18/2023] Open
Abstract
Reproduction is highly sensitive to changes in physiology and the external environment. Neuropeptides are evolutionarily conserved signaling molecules that regulate multiple physiological processes. However, the potential reproductive roles of many neuropeptide signaling pathways remain underexplored. Here, we describe the results of RNAi-based screens in Drosophila melanogaster to identify neuropeptides/neuropeptide receptors with potential roles in oogenesis. The screen read-outs were either the number of eggs laid per female per day over time or fluorescence microscopy analysis of dissected ovaries. We found that the orphan neuropeptide receptor encoded by moody (homologous to mammalian melatonin receptors) is likely required in somatic cells for normal egg production and proper germline stem cell maintenance. However, the egg laying screens had low signal-to-noise ratio and did not lead to the identification of additional candidates. Thus, although egg count assays might be useful for large-scale screens to identify oogenesis regulators that result in dramatic changes in oogenesis, more labor-intensive microscopy-based screen are better applicable for identifying new physiological regulators of oogenesis with more subtle phenotypes.
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18
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Faber AIE, van der Zwaag M, Schepers H, Eggens-Meijer E, Kanon B, IJsebaart C, Kuipers J, Giepmans BNG, Freire R, Grzeschik NA, Rabouille C, Sibon OCM. Vps13 is required for timely removal of nurse cell corpses. Development 2020; 147:dev.191759. [PMID: 32994170 DOI: 10.1242/dev.191759] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2020] [Accepted: 09/15/2020] [Indexed: 12/25/2022]
Abstract
Programmed cell death and consecutive removal of cellular remnants is essential for development. During late stages of Drosophila melanogaster oogenesis, the small somatic follicle cells that surround the large nurse cells promote non-apoptotic nurse cell death, subsequently engulf them, and contribute to the timely removal of nurse cell corpses. Here, we identify a role for Vps13 in the timely removal of nurse cell corpses downstream of developmental programmed cell death. Vps13 is an evolutionarily conserved peripheral membrane protein associated with membrane contact sites and lipid transfer. It is expressed in late nurse cells, and persistent nurse cell remnants are observed when Vps13 is depleted from nurse cells but not from follicle cells. Microscopic analysis revealed enrichment of Vps13 in close proximity to the plasma membrane and the endoplasmic reticulum in nurse cells undergoing degradation. Ultrastructural analysis uncovered the presence of an underlying Vps13-dependent membranous structure in close association with the plasma membrane. The newly identified structure and function suggests the presence of a Vps13-dependent process required for complete degradation of bulky remnants of dying cells.
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Affiliation(s)
- Anita I E Faber
- Department of Biomedical Sciences of Cells and Systems, University Medical Center Groningen, The University of Groningen, 9713 AV, Groningen, The Netherlands
| | - Marianne van der Zwaag
- Department of Biomedical Sciences of Cells and Systems, University Medical Center Groningen, The University of Groningen, 9713 AV, Groningen, The Netherlands
| | - Hein Schepers
- Department of Biomedical Sciences of Cells and Systems, University Medical Center Groningen, The University of Groningen, 9713 AV, Groningen, The Netherlands
| | - Ellie Eggens-Meijer
- Department of Biomedical Sciences of Cells and Systems, University Medical Center Groningen, The University of Groningen, 9713 AV, Groningen, The Netherlands
| | - Bart Kanon
- Department of Biomedical Sciences of Cells and Systems, University Medical Center Groningen, The University of Groningen, 9713 AV, Groningen, The Netherlands
| | - Carmen IJsebaart
- Department of Biomedical Sciences of Cells and Systems, University Medical Center Groningen, The University of Groningen, 9713 AV, Groningen, The Netherlands
| | - Jeroen Kuipers
- Department of Biomedical Sciences of Cells and Systems, University Medical Center Groningen, The University of Groningen, 9713 AV, Groningen, The Netherlands
| | - Ben N G Giepmans
- Department of Biomedical Sciences of Cells and Systems, University Medical Center Groningen, The University of Groningen, 9713 AV, Groningen, The Netherlands
| | - Raimundo Freire
- Unidad de Investigación/FIISC, Hospital Universitario de Canarias, Ofra s/n, La Cuesta, 38320 San Cristóbal de La Laguna, Tenerife, Spain.,Instituto de Tecnologías Biomédicas, Universidad de La Laguna, 38200 San Cristóbal de La Laguna, Tenerife, Spain.,Facultad de Ciencias de la Salud, Universidad Fernando Pessoa Canarias, 35450 Las Palmas de Gran Canaria, Spain
| | - Nicola A Grzeschik
- Department of Biomedical Sciences of Cells and Systems, University Medical Center Groningen, The University of Groningen, 9713 AV, Groningen, The Netherlands
| | - Catherine Rabouille
- Department of Biomedical Sciences of Cells and Systems, University Medical Center Groningen, The University of Groningen, 9713 AV, Groningen, The Netherlands.,Hubrecht Institute, University of Utrecht, 3584 CT, Utrecht, The Netherlands
| | - Ody C M Sibon
- Department of Biomedical Sciences of Cells and Systems, University Medical Center Groningen, The University of Groningen, 9713 AV, Groningen, The Netherlands
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19
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Moulton MJ, Humphreys GB, Kim A, Letsou A. O-GlcNAcylation Dampens Dpp/BMP Signaling to Ensure Proper Drosophila Embryonic Development. Dev Cell 2020; 53:330-343.e3. [DOI: 10.1016/j.devcel.2020.04.001] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2019] [Revised: 01/15/2020] [Accepted: 03/31/2020] [Indexed: 01/09/2023]
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20
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Yalonetskaya A, Mondragon AA, Hintze ZJ, Holmes S, McCall K. Nuclear degradation dynamics in a nonapoptotic programmed cell death. Cell Death Differ 2020; 27:711-724. [PMID: 31285547 PMCID: PMC7206136 DOI: 10.1038/s41418-019-0382-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2018] [Revised: 05/28/2019] [Accepted: 06/17/2019] [Indexed: 01/01/2023] Open
Abstract
Nuclear degradation is a major event during programmed cell death (PCD). The breakdown of nuclear components has been well characterized during apoptosis, one form of PCD. Many nonapoptotic forms of PCD have been identified, but our understanding of nuclear degradation during those events is limited. Here, we take advantage of Drosophila oogenesis to investigate nuclear degeneration during stress-induced apoptotic and developmental nonapoptotic cell death in the same cell type in vivo. We find that nuclear Lamin, a caspase substrate, dissociates from the nucleus as an early event during apoptosis, but remains associated with nuclei during nonapoptotic cell death. Lamin reveals a series of changes in nuclear architecture during nonapoptotic death, including nuclear crenellations and involutions. Stretch follicle cells contribute to these architecture changes, and phagocytic and lysosome-associated machinery in stretch follicle cells promote Lamin degradation. More specifically, we find that the lysosomal cathepsin CP1 facilitates Lamin degradation.
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Affiliation(s)
- Alla Yalonetskaya
- Department of Biology, Boston University, 5 Cummington Mall, Boston, MA, 02215, USA
| | - Albert A Mondragon
- Department of Biology, Boston University, 5 Cummington Mall, Boston, MA, 02215, USA
- Program in Molecular Biology, Cell Biology, and Biochemistry, Boston University, Boston, MA, 02215, USA
| | - Zackary J Hintze
- Department of Biology, Boston University, 5 Cummington Mall, Boston, MA, 02215, USA
| | - Susan Holmes
- Department of Statistics, Stanford University, Stanford, CA, 94305, USA
| | - Kimberly McCall
- Department of Biology, Boston University, 5 Cummington Mall, Boston, MA, 02215, USA.
- Program in Molecular Biology, Cell Biology, and Biochemistry, Boston University, Boston, MA, 02215, USA.
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21
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Manning LA, Perez-Vale KZ, Schaefer KN, Sewell MT, Peifer M. The Drosophila Afadin and ZO-1 homologues Canoe and Polychaetoid act in parallel to maintain epithelial integrity when challenged by adherens junction remodeling. Mol Biol Cell 2019; 30:1938-1960. [PMID: 31188739 PMCID: PMC6727765 DOI: 10.1091/mbc.e19-04-0209] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
During morphogenesis, cells must change shape and move without disrupting tissue integrity. This requires cell-cell junctions to allow dynamic remodeling while resisting forces generated by the actomyosin cytoskeleton. Multiple proteins play roles in junctional-cytoskeletal linkage, but the mechanisms by which they act remain unclear. Drosophila Canoe maintains adherens junction-cytoskeletal linkage during gastrulation. Canoe's mammalian homologue Afadin plays similar roles in cultured cells, working in parallel with ZO-1 proteins, particularly at multicellular junctions. We take these insights back to the fly embryo, exploring how cells maintain epithelial integrity when challenged by adherens junction remodeling during germband extension and dorsal closure. We found that Canoe helps cells maintain junctional-cytoskeletal linkage when challenged by the junctional remodeling inherent in mitosis, cell intercalation, and neuroblast invagination or by forces generated by the actomyosin cable at the leading edge. However, even in the absence of Canoe, many cells retain epithelial integrity. This is explained by a parallel role played by the ZO-1 homologue Polychaetoid. In embryos lacking both Canoe and Polychaetoid, cell junctions fail early, with multicellular junctions especially sensitive, leading to widespread loss of epithelial integrity. Our data suggest that Canoe and Polychaetoid stabilize Bazooka/Par3 at cell-cell junctions, helping maintain balanced apical contractility and tissue integrity.
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Affiliation(s)
- Lathiena A Manning
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599
| | - Kia Z Perez-Vale
- Curriculum in Genetics and Molecular Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599
| | - Kristina N Schaefer
- Curriculum in Genetics and Molecular Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599
| | - Mycah T Sewell
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599
| | - Mark Peifer
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599.,Curriculum in Genetics and Molecular Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599.,Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599
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22
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Mirth CK, Nogueira Alves A, Piper MD. Turning food into eggs: insights from nutritional biology and developmental physiology of Drosophila. CURRENT OPINION IN INSECT SCIENCE 2019; 31:49-57. [PMID: 31109673 DOI: 10.1016/j.cois.2018.08.006] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/17/2018] [Accepted: 08/27/2018] [Indexed: 06/09/2023]
Abstract
Nutrition plays a central role in fecundity, regulating the onset of reproductive maturity, egg production, and the survival and health of offspring from insects to humans. Although decades of research have worked to uncover how nutrition mediates these effects, it has proven difficult to disentangle the relative role of nutrients as the raw material for egg and offspring development versus their role in stimulating endocrine cascades necessary to drive development. This has been further complicated by the fact that both nutrients and the signalling cascades they regulate interact in complex ways to control fecundity. Separating the two effects becomes important when trying to understand how fecundity is regulated, and in devising strategies to offset the negative effects of nutrition on reproductive health. In this review, we use the extensive literature on egg development in the fruit fly Drosophila melanogaster to explore how the nutrients from food provide the building blocks and stimulate signalling cascades necessary for making an egg.
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Affiliation(s)
- Christen K Mirth
- School of Biological Sciences, Monash University, Melbourne, Victoria 3800, Australia.
| | - André Nogueira Alves
- School of Biological Sciences, Monash University, Melbourne, Victoria 3800, Australia
| | - Matthew Dw Piper
- School of Biological Sciences, Monash University, Melbourne, Victoria 3800, Australia
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23
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Baena-Lopez LA, Arthurton L, Bischoff M, Vincent JP, Alexandre C, McGregor R. Novel initiator caspase reporters uncover previously unknown features of caspase-activating cells. Development 2018; 145:dev170811. [PMID: 30413561 PMCID: PMC6288387 DOI: 10.1242/dev.170811] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2018] [Accepted: 10/31/2018] [Indexed: 12/30/2022]
Abstract
The caspase-mediated regulation of many cellular processes, including apoptosis, justifies the substantial interest in understanding all of the biological features of these enzymes. To complement functional assays, it is crucial to identify caspase-activating cells in live tissues. Our work describes novel initiator caspase reporters that, for the first time, provide direct information concerning the initial steps of the caspase activation cascade in Drosophila tissues. One of our caspase sensors capitalises on the rapid subcellular localisation change of a fluorescent marker to uncover novel cellular apoptotic events relating to the actin-mediated positioning of the nucleus before cell delamination. The other construct benefits from caspase-induced nuclear translocation of a QF transcription factor. This feature enables the genetic manipulation of caspase-activating cells and reveals the spatiotemporal patterns of initiator caspase activity. Collectively, our sensors offer experimental opportunities not available by using previous reporters and have proven useful to illuminate previously unknown aspects of caspase-dependent processes in apoptotic and non-apoptotic cellular scenarios.
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Affiliation(s)
- Luis Alberto Baena-Lopez
- Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxfordshire, OX1 3RE, UK
| | - Lewis Arthurton
- Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxfordshire, OX1 3RE, UK
| | - Marcus Bischoff
- Biomolecular Sciences Research Complex, University of St Andrews, North Haugh, St Andrews, Fife, Scotland, KY16 9ST, UK
| | | | | | - Reuben McGregor
- Faculty of Medical and Health Sciences, Molecular Medicine & Pathology, The University of Auckland, M&HS Building 502, 85 Park Road, Grafton, Auckland 1023, New Zealand
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24
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Serizier SB, McCall K. Scrambled Eggs: Apoptotic Cell Clearance by Non-Professional Phagocytes in the Drosophila Ovary. Front Immunol 2017; 8:1642. [PMID: 29238344 PMCID: PMC5712531 DOI: 10.3389/fimmu.2017.01642] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2017] [Accepted: 11/09/2017] [Indexed: 01/20/2023] Open
Abstract
For half of a century, it has been known that non-professional phagocytes, such as fibroblasts, endothelial, and epithelial cells, are capable of efferocytosis (engulfment of apoptotic cells). Non-professional phagocytes differ from professional phagocytes in the range and efficiency of engulfment. Much of the recognition and underlying signaling machinery between non-professional and professional phagocytes is the same, but it is not known how the engulfment capacity of non-professional phagocytes is controlled. Moreover, the signaling networks involved in cell corpse recognition, engulfment, and phagosome maturation are only partially understood. The Drosophila ovary provides an excellent system to investigate the regulation of phagocytic activity by epithelial cells, a major class of non-professional phagocytes. During Drosophila oogenesis, mid-stage egg chambers undergo apoptosis of the germline in response to nutrient deprivation. Epithelial follicle cells then undergo major cell shape changes and concomitantly engulf the germline material. Our previous work has established that Draper and the integrin α-PS3/β-PS heterodimer are required in follicle cells for germline cell clearance. In addition, we have characterized phagosome maturation pathways, and found that the JNK pathway amplifies the engulfment response. In this review, we discuss recent advances on the interplay between engulfment pathways in the follicular epithelium for cell clearance in the Drosophila ovary. We also provide a comparison to apoptotic cell clearance mechanisms in C. elegans and mammals, illustrating strong conservation of efferocytosis mechanisms by non-professional phagocytes.
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Affiliation(s)
- Sandy B Serizier
- Department of Biology, Boston University, Boston, MA, United States.,Graduate Program in Molecular Biology, Cell Biology and Biochemistry, Boston University, Boston, MA, United States
| | - Kimberly McCall
- Department of Biology, Boston University, Boston, MA, United States
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25
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Non-apoptotic cell death in animal development. Cell Death Differ 2017; 24:1326-1336. [PMID: 28211869 DOI: 10.1038/cdd.2017.20] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2016] [Revised: 01/18/2017] [Accepted: 01/19/2017] [Indexed: 01/22/2023] Open
Abstract
Programmed cell death (PCD) is an important process in the development of multicellular organisms. Apoptosis, a form of PCD characterized morphologically by chromatin condensation, membrane blebbing, and cytoplasm compaction, and molecularly by the activation of caspase proteases, has been extensively investigated. Studies in Caenorhabditis elegans, Drosophila, mice, and the developing chick have revealed, however, that developmental PCD also occurs through other mechanisms, morphologically and molecularly distinct from apoptosis. Some non-apoptotic PCD pathways, including those regulating germ cell death in Drosophila, still appear to employ caspases. However, another prominent cell death program, linker cell-type death (LCD), is morphologically conserved, and independent of the key genes that drive apoptosis, functioning, at least in part, through the ubiquitin proteasome system. These non-apoptotic processes may serve as backup programs when caspases are inactivated or unavailable, or, more likely, as freestanding cell culling programs. Non-apoptotic PCD has been documented extensively in the developing nervous system, and during the formation of germline and somatic gonadal structures, suggesting that preservation of these mechanisms is likely under strong selective pressure. Here, we discuss our current understanding of non-apoptotic PCD in animal development, and explore possible roles for LCD and other non-apoptotic developmental pathways in vertebrates. We raise the possibility that during vertebrate development, apoptosis may not be the major PCD mechanism.
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26
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Reliance of Wolbachia on High Rates of Host Proteolysis Revealed by a Genome-Wide RNAi Screen of Drosophila Cells. Genetics 2017; 205:1473-1488. [PMID: 28159754 DOI: 10.1534/genetics.116.198903] [Citation(s) in RCA: 58] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2016] [Accepted: 01/27/2017] [Indexed: 11/18/2022] Open
Abstract
Wolbachia are gram-negative, obligate, intracellular bacteria carried by a majority of insect species worldwide. Here we use a Wolbachia-infected Drosophila cell line and genome-wide RNA interference (RNAi) screening to identify host factors that influence Wolbachia titer. By screening an RNAi library targeting 15,699 transcribed host genes, we identified 36 candidate genes that dramatically reduced Wolbachia titer and 41 that increased Wolbachia titer. Host gene knockdowns that reduced Wolbachia titer spanned a broad array of biological pathways including genes that influenced mitochondrial function and lipid metabolism. In addition, knockdown of seven genes in the host ubiquitin and proteolysis pathways significantly reduced Wolbachia titer. To test the in vivo relevance of these results, we found that drug and mutant inhibition of proteolysis reduced levels of Wolbachia in the Drosophila oocyte. The presence of Wolbachia in either cell lines or oocytes dramatically alters the distribution and abundance of ubiquitinated proteins. Functional studies revealed that maintenance of Wolbachia titer relies on an intact host Endoplasmic Reticulum (ER)-associated protein degradation pathway (ERAD). Accordingly, electron microscopy studies demonstrated that Wolbachia is intimately associated with the host ER and dramatically alters the morphology of this organelle. Given Wolbachia lack essential amino acid biosynthetic pathways, the reliance of Wolbachia on high rates of host proteolysis via ubiquitination and the ERAD pathways may be a key mechanism for provisioning Wolbachia with amino acids. In addition, the reliance of Wolbachia on the ERAD pathway and disruption of ER morphology suggests a previously unsuspected mechanism for Wolbachia's potent ability to prevent RNA virus replication.
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27
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Imagawa Y, Saitoh T, Tsujimoto Y. Vital staining for cell death identifies Atg9a-dependent necrosis in developmental bone formation in mouse. Nat Commun 2016; 7:13391. [PMID: 27811852 PMCID: PMC5097171 DOI: 10.1038/ncomms13391] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2016] [Accepted: 09/27/2016] [Indexed: 02/06/2023] Open
Abstract
Programmed cell death has a crucial role in various biological events, including developmental morphogenesis. Recent evidence indicates that necrosis contributes to programmed cell death in addition to apoptosis, but it is unclear whether necrosis acts as a compensatory mechanism for failure of apoptosis or has an intrinsic role during development. In contrast to apoptosis, there have been no techniques for imaging physiological necrosis in vivo. Here we employ vital staining using propidium iodide to identify cells with plasma membrane disruption (necrotic cells) in mouse embryos. We discover a form of necrosis at the bone surface, which does not occur in embryos with deficiency of the autophagy-related gene Atg9a, although it is unaffected by Atg5 knockout. We also find abnormalities of the bone surface in Atg9a knockout mice, suggesting an important role of Atg9a-dependent necrosis in bone surface formation. These findings suggest that necrosis has an active role in developmental morphogenesis.
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Affiliation(s)
- Yusuke Imagawa
- Department of Molecular and Cellular Biology, Research Institute of Osaka Medical Center for Cancer and Cardiovascular Diseases, 1-3-2 Nakamichi, Higashinari-ku, Osaka 537-8511, Japan.,Laboratory of Molecular Genetics, Department of Medical Genetics, Graduate School of Medicine, Osaka University, 2-2 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Tatsuya Saitoh
- Department of Inflammation Biology, Institute for Enzyme Research, Tokushima University, 3-18-15 Kuramoto-cho, Tokushima 770-8503, Japan.,Laboratory of Host Defense, WPI Immunology Frontier Research Center, Osaka University, 3-1 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Yoshihide Tsujimoto
- Department of Molecular and Cellular Biology, Research Institute of Osaka Medical Center for Cancer and Cardiovascular Diseases, 1-3-2 Nakamichi, Higashinari-ku, Osaka 537-8511, Japan.,Laboratory of Molecular Genetics, Department of Medical Genetics, Graduate School of Medicine, Osaka University, 2-2 Yamadaoka, Suita, Osaka 565-0871, Japan
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28
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Ronai I, Oldroyd BP, Vergoz V. Queen pheromone regulates programmed cell death in the honey bee worker ovary. INSECT MOLECULAR BIOLOGY 2016; 25:646-652. [PMID: 27321063 DOI: 10.1111/imb.12250] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
In social insect colonies the presence of a queen, secreting her pheromones, is a key environmental cue for regulating the reproductive state of workers. However, until recently the proximate molecular mechanisms underlying facultative worker sterility were unidentified. Studies into worker oogenesis in the honey bee (Apis mellifera) have indicated that programmed cell death is central to the regulation of oogenesis. Here we investigate how queen pheromone, age of the worker and ovary state affect both programmed cell death and cell number in worker ovaries. We describe a novel method to simultaneously measure programmed cell death (caspase activity) and live cell number (estimated from the amount of adenosine triphosphate) in an insect tissue. Workers exposed to queen pheromone have higher levels of caspase activity in the ovary than those not exposed. Our results suggest that queen pheromone triggers programmed cell death at the mid-oogenesis checkpoint causing the abortion of worker oocytes and reproductive inhibition of the worker caste. Nonetheless, high caspase activity is present in activated ovaries from workers not exposed to queen pheromone. This caspase activity is most likely to be from the nurse cells undergoing programmed cell death, in late oogenesis, for normal oocyte development. Our study shows that the social environment of an organism can influence programmed cell death within a tissue.
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Affiliation(s)
- I Ronai
- Behaviour and Genetics of Social Insects Laboratory, School of Biological Sciences, The University of Sydney, Sydney, NSW, Australia
| | - B P Oldroyd
- Behaviour and Genetics of Social Insects Laboratory, School of Biological Sciences, The University of Sydney, Sydney, NSW, Australia
| | - V Vergoz
- Behaviour and Genetics of Social Insects Laboratory, School of Biological Sciences, The University of Sydney, Sydney, NSW, Australia
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29
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Timmons AK, Mondragon AA, Meehan TL, McCall K. Control of non-apoptotic nurse cell death by engulfment genes in Drosophila. Fly (Austin) 2016; 11:104-111. [PMID: 27686122 DOI: 10.1080/19336934.2016.1238993] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Programmed cell death occurs as a normal part of oocyte development in Drosophila. For each egg that is formed, 15 germline-derived nurse cells transfer their cytoplasmic contents into the oocyte and die. Disruption of apoptosis or autophagy only partially inhibits the death of the nurse cells, indicating that other mechanisms significantly contribute to nurse cell death. Recently, we demonstrated that the surrounding stretch follicle cells non-autonomously promote nurse cell death during late oogenesis and that phagocytosis genes including draper, ced-12, and the JNK pathway are crucial for this process. When phagocytosis genes are inhibited in the follicle cells, events specifically associated with death of the nurse cells are impaired. Death of the nurse cells is not completely blocked in draper mutants, suggesting that other engulfment receptors are involved. Indeed, we found that the integrin subunit, αPS3, is enriched on stretch follicle cells during late oogenesis and is required for elimination of the nurse cells. Moreover, double mutant analysis revealed that integrins act in parallel to draper. Death of nurse cells in the Drosophila ovary is a unique example of programmed cell death that is both non-apoptotic and non-cell autonomously controlled.
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Affiliation(s)
| | | | - Tracy L Meehan
- a Department of Biology , Boston University , Boston , MA
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Meehan TL, Joudi TF, Timmons AK, Taylor JD, Habib CS, Peterson JS, Emmanuel S, Franc NC, McCall K. Components of the Engulfment Machinery Have Distinct Roles in Corpse Processing. PLoS One 2016; 11:e0158217. [PMID: 27347682 PMCID: PMC4922577 DOI: 10.1371/journal.pone.0158217] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2015] [Accepted: 06/13/2016] [Indexed: 01/10/2023] Open
Abstract
Billions of cells die in our bodies on a daily basis and are engulfed by phagocytes. Engulfment, or phagocytosis, can be broken down into five basic steps: attraction of the phagocyte, recognition of the dying cell, internalization, phagosome maturation, and acidification. In this study, we focus on the last two steps, which can collectively be considered corpse processing, in which the engulfed material is degraded. We use the Drosophila ovarian follicle cells as a model for engulfment of apoptotic cells by epithelial cells. We show that engulfed material is processed using the canonical corpse processing pathway involving the small GTPases Rab5 and Rab7. The phagocytic receptor Draper is present on the phagocytic cup and on nascent, phosphatidylinositol 3-phosphate (PI(3)P)- and Rab7-positive phagosomes, whereas integrins are maintained on the cell surface during engulfment. Due to the difference in subcellular localization, we investigated the role of Draper, integrins, and downstream signaling components in corpse processing. We found that some proteins were required for internalization only, while others had defects in corpse processing as well. This suggests that several of the core engulfment proteins are required for distinct steps of engulfment. We also performed double mutant analysis and found that combined loss of draper and αPS3 still resulted in a small number of engulfed vesicles. Therefore, we investigated another known engulfment receptor, Crq. We found that loss of all three receptors did not inhibit engulfment any further, suggesting that Crq does not play a role in engulfment by the follicle cells. A more complete understanding of how the engulfment and corpse processing machinery interact may enable better understanding and treatment of diseases associated with defects in engulfment by epithelial cells.
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Affiliation(s)
- Tracy L. Meehan
- Department of Biology, Boston University, Boston, Massachusetts, United States of America
- * E-mail: (KM); (TM)
| | - Tony F. Joudi
- Department of Biology, Boston University, Boston, Massachusetts, United States of America
| | - Allison K. Timmons
- Department of Biology, Boston University, Boston, Massachusetts, United States of America
| | - Jeffrey D. Taylor
- Department of Biology, Boston University, Boston, Massachusetts, United States of America
| | - Corey S. Habib
- Department of Biology, Boston University, Boston, Massachusetts, United States of America
| | - Jeanne S. Peterson
- Department of Biology, Boston University, Boston, Massachusetts, United States of America
| | - Shanan Emmanuel
- Department of Biology, Boston University, Boston, Massachusetts, United States of America
| | - Nathalie C. Franc
- The Scripps Research Institute, Department of Immunology and Microbial Science, La Jolla, California, United States of America
| | - Kimberly McCall
- Department of Biology, Boston University, Boston, Massachusetts, United States of America
- * E-mail: (KM); (TM)
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31
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Winkler F, Gummalla M, Künneke L, Lv Z, Zippelius A, Aspelmeier T, Grosshans J. Fluctuation Analysis of Centrosomes Reveals a Cortical Function of Kinesin-1. Biophys J 2016; 109:856-68. [PMID: 26331244 PMCID: PMC4564942 DOI: 10.1016/j.bpj.2015.07.044] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2014] [Revised: 07/20/2015] [Accepted: 07/31/2015] [Indexed: 01/28/2023] Open
Abstract
The actin and microtubule networks form the dynamic cytoskeleton. Network dynamics is driven by molecular motors applying force onto the networks and the interactions between the networks. Here we assay the dynamics of centrosomes in the scale of seconds as a proxy for the movement of microtubule asters. With this assay we want to detect the role of specific motors and of network interaction. During interphase of syncytial embryos of Drosophila, cortical actin and the microtubule network depend on each other. Centrosomes induce cortical actin to form caps, whereas F-actin anchors microtubules to the cortex. In addition, lateral interactions between microtubule asters are assumed to be important for regular spatial organization of the syncytial embryo. The functional interaction between the microtubule asters and cortical actin has been largely analyzed in a static manner, so far. We recorded the movement of centrosomes at 1 Hz and analyzed their fluctuations for two processes—pair separation and individual movement. We found that F-actin is required for directional movements during initial centrosome pair separation, because separation proceeds in a diffusive manner in latrunculin-injected embryos. For assaying individual movement, we established a fluctuation parameter as the deviation from temporally and spatially slowly varying drift movements. By analysis of mutant and drug-injected embryos, we found that the fluctuations were suppressed by both cortical actin and microtubules. Surprisingly, the microtubule motor Kinesin-1 also suppressed fluctuations to a similar degree as F-actin. Kinesin-1 may mediate linkage of the microtubule (+)-ends to the actin cortex. Consistent with this model is our finding that Kinesin-1-GFP accumulates at the cortical actin caps.
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Affiliation(s)
- Franziska Winkler
- Institute for Developmental Biochemistry, Medical School, Georg-August-University Göttingen, Göttingen, Germany
| | - Maheshwar Gummalla
- Institute for Developmental Biochemistry, Medical School, Georg-August-University Göttingen, Göttingen, Germany
| | - Lutz Künneke
- Institute for Theoretical Physics, Georg-August-University Göttingen, Göttingen, Germany
| | - Zhiyi Lv
- Institute for Developmental Biochemistry, Medical School, Georg-August-University Göttingen, Göttingen, Germany
| | - Annette Zippelius
- Institute for Theoretical Physics, Georg-August-University Göttingen, Göttingen, Germany
| | - Timo Aspelmeier
- Institute for Mathematical Stochastics, Georg-August-University Göttingen, Göttingen, Germany; Felix Bernstein Institute for Statistics in the Biosciences, Georg-August-University Göttingen, Göttingen, Germany
| | - Jörg Grosshans
- Institute for Developmental Biochemistry, Medical School, Georg-August-University Göttingen, Göttingen, Germany.
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32
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Patel PH, Barbee SA, Blankenship JT. GW-Bodies and P-Bodies Constitute Two Separate Pools of Sequestered Non-Translating RNAs. PLoS One 2016; 11:e0150291. [PMID: 26930655 PMCID: PMC4773245 DOI: 10.1371/journal.pone.0150291] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2015] [Accepted: 02/11/2016] [Indexed: 01/05/2023] Open
Abstract
Non-translating RNAs that have undergone active translational repression are culled from the cytoplasm into P-bodies for decapping-dependent decay or for sequestration. Organisms that use microRNA-mediated RNA silencing have an additional pathway to remove RNAs from active translation. Consequently, proteins that govern microRNA-mediated silencing, such as GW182/Gw and AGO1, are often associated with the P-bodies of higher eukaryotic organisms. Due to the presence of Gw, these structures have been referred to as GW-bodies. However, several reports have indicated that GW-bodies have different dynamics to P-bodies. Here, we use live imaging to examine GW-body and P-body dynamics in the early Drosophila melanogaster embryo. While P-bodies are present throughout early embryonic development, cytoplasmic GW-bodies only form in significant numbers at the midblastula transition. Unlike P-bodies, which are predominantly cytoplasmic, GW-bodies are present in both nuclei and the cytoplasm. RNA decapping factors such as DCP1, Me31B, and Hpat are not associated with GW-bodies, indicating that P-bodies and GW-bodies are distinct structures. Furthermore, known Gw interactors such as AGO1 and the CCR4-NOT deadenylation complex, which have been shown to be important for Gw function, are also not present in GW-bodies. Use of translational inhibitors puromycin and cycloheximide, which respectively increase or decrease cellular pools of non-translating RNAs, alter GW-body size, underscoring that GW-bodies are composed of non-translating RNAs. Taken together, these data indicate that active translational silencing most likely does not occur in GW-bodies. Instead GW-bodies most likely function as repositories for translationally silenced RNAs. Finally, inhibition of zygotic gene transcription is unable to block the formation of either P-bodies or GW-bodies in the early embryo, suggesting that these structures are composed of maternal RNAs.
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Affiliation(s)
- Prajal H. Patel
- Department of Biological Sciences and Eleanor Roosevelt Institute, University of Denver, Denver, Colorado, United States of America
| | - Scott A. Barbee
- Department of Biological Sciences and Eleanor Roosevelt Institute, University of Denver, Denver, Colorado, United States of America
- Molecular and Cellular Biophysics Program, University of Denver, Denver, Colorado, United States of America
- * E-mail: (JTB); (SAB)
| | - J. Todd Blankenship
- Department of Biological Sciences and Eleanor Roosevelt Institute, University of Denver, Denver, Colorado, United States of America
- Molecular and Cellular Biophysics Program, University of Denver, Denver, Colorado, United States of America
- * E-mail: (JTB); (SAB)
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33
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Phagocytosis genes nonautonomously promote developmental cell death in the Drosophila ovary. Proc Natl Acad Sci U S A 2016; 113:E1246-55. [PMID: 26884181 DOI: 10.1073/pnas.1522830113] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Programmed cell death (PCD) is usually considered a cell-autonomous suicide program, synonymous with apoptosis. Recent research has revealed that PCD is complex, with at least a dozen cell death modalities. Here, we demonstrate that the large-scale nonapoptotic developmental PCD in the Drosophila ovary occurs by an alternative cell death program where the surrounding follicle cells nonautonomously promote death of the germ line. The phagocytic machinery of the follicle cells, including Draper, cell death abnormality (Ced)-12, and c-Jun N-terminal kinase (JNK), is essential for the death and removal of germ-line-derived nurse cells during late oogenesis. Cell death events including acidification, nuclear envelope permeabilization, and DNA fragmentation of the nurse cells are impaired when phagocytosis is inhibited. Moreover, elimination of a small subset of follicle cells prevents nurse cell death and cytoplasmic dumping. Developmental PCD in the Drosophila ovary is an intriguing example of nonapoptotic, nonautonomous PCD, providing insight on the diversity of cell death mechanisms.
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34
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Abstract
Programmed cell death (PCD) is essential for health and development. Generally, the last step of PCD is clearance, or engulfment, by phagocytes. Engulfment can be broken down into five basic steps: attraction of the phagocyte, recognition of the dying cell, internalization, phagosome maturation, and acidification of the engulfed material. The Drosophila melanogaster ovary serves as an excellent model to study diverse types of PCD and engulfment by epithelial cells. Here, we describe several methods to detect and analyze multiple steps of engulfment in the Drosophila ovary: recognition, vesicle uptake, phagosome maturation, and acidification. Annexin V detects phosphatidylserine, which is flipped to the outer leaflet of the plasma membrane of apoptotic cells, serving as an "eat me" signal. Several germline markers including tral-GFP, Orb, and cleaved Dcp-1 can all be used to label the germline and visualize its uptake into engulfing follicle cells. Drosophila strains expressing GFP and mCherry protein fusions can enable a detailed analysis of phagosome maturation. LysoTracker labels highly acidified compartments, marking phagolysosomes. Together these labels can be used to mark the progression of engulfment in Drosophila follicle cells.
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35
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Abstract
Drosophila egg chamber development depends on a number of dynamic cellular processes that contribute to the final shape and function of the egg. We can gain insight into the mechanisms underlying these events by combining the power of Drosophila genetics and ex vivo live imaging. During developmental stages 1-8, egg chambers rotate around their anterior-posterior axes due to collective migration of the follicular epithelium. This motion is required for the proper elongation of the egg chamber. Here, we describe how to prepare stage 1-8 egg chambers for live imaging. We provide alternate protocols for the use of inverted or upright microscopes and describe ways to stabilize egg chambers to reduce drift during imaging. We discuss the advantages and limitations of these methods to assist the researcher in choosing an appropriate method based on experimental need and available resources.
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Affiliation(s)
- Maureen Cetera
- Department of Molecular Genetics and Cell Biology, The University of Chicago, 920 East 58th Street, Chicago, IL, 60637, USA
- Committee on Development, Regeneration and Stem Cell Biology, The University of Chicago, 920 East 58th Street, Chicago, IL, 60637, USA
| | - Lindsay Lewellyn
- Department of Biological Sciences, Butler University, 4600 Sunset Boulevard, Indianapolis, IN, 46208, USA
| | - Sally Horne-Badovinac
- Department of Molecular Genetics and Cell Biology, The University of Chicago, 920 East 58th Street, Chicago, IL, 60637, USA.
- Committee on Development, Regeneration and Stem Cell Biology, The University of Chicago, 920 East 58th Street, Chicago, IL, 60637, USA.
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36
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Rojas-Ríos P, Chartier A, Pierson S, Séverac D, Dantec C, Busseau I, Simonelig M. Translational Control of Autophagy by Orb in the Drosophila Germline. Dev Cell 2015; 35:622-631. [DOI: 10.1016/j.devcel.2015.11.003] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2013] [Revised: 09/02/2015] [Accepted: 11/04/2015] [Indexed: 11/16/2022]
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37
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Meehan TL, Kleinsorge SE, Timmons AK, Taylor JD, McCall K. Polarization of the epithelial layer and apical localization of integrins are required for engulfment of apoptotic cells in the Drosophila ovary. Dis Model Mech 2015; 8:1603-14. [PMID: 26398951 PMCID: PMC4728319 DOI: 10.1242/dmm.021998] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2015] [Accepted: 09/14/2015] [Indexed: 12/28/2022] Open
Abstract
Inefficient clearance of dead cells or debris by epithelial cells can lead to or exacerbate debilitating conditions such as retinitis pigmentosa, macular degeneration, chronic obstructive pulmonary disease and asthma. Despite the importance of engulfment by epithelial cells, little is known about the molecular changes that are required within these cells. The misregulation of integrins has previously been associated with disease states, suggesting that a better understanding of the regulation of receptor trafficking could be key to treating diseases caused by defects in phagocytosis. Here, we demonstrate that the integrin heterodimer αPS3/βPS becomes apically enriched and is required for engulfment by the epithelial follicle cells of the Drosophila ovary. We found that integrin heterodimer localization and function is largely directed by the α-subunit. Moreover, proper cell polarity promotes asymmetric integrin enrichment, suggesting that αPS3/βPS trafficking occurs in a polarized fashion. We show that several genes previously known for their roles in trafficking and cell migration are also required for engulfment. Moreover, as in mammals, the same α-integrin subunit is required by professional and non-professional phagocytes and migrating cells in Drosophila. Our findings suggest that migrating and engulfing cells use common machinery, and demonstrate a crucial role for integrin function and polarized trafficking of integrin subunits during engulfment. This study also establishes the epithelial follicle cells of the Drosophila ovary as a powerful model for understanding the molecular changes required for engulfment by a polarized epithelium. Summary: Apical integrin localization, mediated by polarized and directed trafficking, is crucial for proper engulfment by epithelial cells.
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Affiliation(s)
- Tracy L Meehan
- Department of Biology, Boston University, 5 Cummington Mall, Boston, MA 02215, USA
| | - Sarah E Kleinsorge
- Department of Biology, Boston University, 5 Cummington Mall, Boston, MA 02215, USA
| | - Allison K Timmons
- Department of Biology, Boston University, 5 Cummington Mall, Boston, MA 02215, USA
| | - Jeffrey D Taylor
- Department of Biology, Boston University, 5 Cummington Mall, Boston, MA 02215, USA
| | - Kimberly McCall
- Department of Biology, Boston University, 5 Cummington Mall, Boston, MA 02215, USA
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38
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Peterson JS, Timmons AK, Mondragon AA, McCall K. The End of the Beginning: Cell Death in the Germline. Curr Top Dev Biol 2015; 114:93-119. [PMID: 26431565 DOI: 10.1016/bs.ctdb.2015.07.025] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Programmed cell death occurs in the germline of many organisms, both as an essential part of development and throughout adult life. Germline cell death can be apoptotic or nonapoptotic, depending on the stimulus or stage of development. Here, we focus on the Drosophila ovary, which is a powerful model for studying diverse types of cell death. In Drosophila, the death of primordial germ cells occurs normally during embryonic development, and germline nurse cells are programmed to die during oocyte development in adult flies. Cell death of previtellogenic egg chambers in adults can also be induced by starvation or other environmental cues. Mid-oogenesis seems to be particularly sensitive to such cues and has been proposed to serve as a checkpoint to avoid the energetically expensive cost of egg production. After the germline dies in mid-oogenesis, the remnants are engulfed by an epithelial layer of follicle cells; thus, the fly ovary also serves as a highly tractable model for engulfment by epithelial cells. These examples of cell death in the fly ovary share many similarities to the types of cell death seen in the mammalian germline. Recent progress in elucidating the molecular mechanisms of cell death in the germline is discussed.
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Affiliation(s)
- Jeanne S Peterson
- Department of Biology, Boston University, Boston, Massachusetts, USA
| | - Allison K Timmons
- Department of Biology, Boston University, Boston, Massachusetts, USA
| | | | - Kimberly McCall
- Department of Biology, Boston University, Boston, Massachusetts, USA.
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39
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Meehan TL, Yalonetskaya A, Joudi TF, McCall K. Detection of Cell Death and Phagocytosis in the Drosophila Ovary. Methods Mol Biol 2015; 1328:191-206. [PMID: 26324439 DOI: 10.1007/978-1-4939-2851-4_14] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Billions of cells die and are cleared throughout the development and homeostasis of an organism. Either improper death or clearance can lead to serious illnesses. In the adult Drosophila ovary, germline cells can die by programmed cell death (PCD) at three distinct stages; here we focus on cell death that occurs in mid- and late oogenesis. In mid-oogenesis, the germline of egg chambers can undergo apoptosis in response to nutrient deprivation. In late oogenesis, the nurse cells are eliminated through a developmentally regulated, non-apoptotic cell death. In this chapter, we describe several methods to detect cell death and phagocytosis in the Drosophila ovary. DAPI stains the chromatin of all cells and can be used to detect morphological changes in cells that die by different mechanisms. TUNEL labels fragmented DNA, which can occur in both apoptotic and non-apoptotic death. LysoTracker, an acidophilic dye, marks acidic vesicles and some dying cells; therefore, it can be used to study both death and phagocytosis. We also describe several antibodies that can be used to investigate cell death and/or phagocytosis: active caspase Dcp-1, membrane markers, and lamins. Many of these antibodies can be used in combination with GFP fusion transgenes for further analysis; we show Rab5-GFP and Rab7-GFP, which can be used to study phagocytosis in further detail.
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Affiliation(s)
- Tracy L Meehan
- Department of Biology, Boston University, Boston, MA, 02215, USA
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40
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Burn KM, Shimada Y, Ayers K, Vemuganti S, Lu F, Hudson AM, Cooley L. Somatic insulin signaling regulates a germline starvation response in Drosophila egg chambers. Dev Biol 2014; 398:206-17. [PMID: 25481758 DOI: 10.1016/j.ydbio.2014.11.021] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2014] [Revised: 11/17/2014] [Accepted: 11/22/2014] [Indexed: 12/31/2022]
Abstract
Egg chambers from starved Drosophila females contain large aggregates of processing (P) bodies and cortically enriched microtubules. As this response to starvation is rapidly reversed upon re-feeding females or culturing egg chambers with exogenous bovine insulin, we examined the role of endogenous insulin signaling in mediating the starvation response. We found that systemic Drosophila insulin-like peptides (dILPs) activate the insulin pathway in follicle cells, which then regulate both microtubule and P body organization in the underlying germline cells. This organization is modulated by the motor proteins Dynein and Kinesin. Dynein activity is required for microtubule and P body organization during starvation, while Kinesin activity is required during nutrient-rich conditions. Blocking the ability of egg chambers to form P body aggregates in response to starvation correlated with reduced progeny survival. These data suggest a potential mechanism to maximize fecundity even during periods of poor nutrient availability, by mounting a protective response in immature egg chambers.
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Affiliation(s)
- K Mahala Burn
- Department of Cell Biology, Yale University School of Medicine, 333 Cedar Street, New Haven, CT 06520, United States
| | - Yuko Shimada
- Graduate School of Life and Environmental Sciences, University of Tsukuba, Seinou-tou D301, Tennoudai 1-1-1, Tsukuba,, Ibaraki 305-8572, Japan
| | - Kathleen Ayers
- Department of Genetics, Yale University School of Medicine, 333 Cedar Street, New Haven, CT 06520, United States
| | - Soumya Vemuganti
- Department of Genetics, Yale University School of Medicine, 333 Cedar Street, New Haven, CT 06520, United States
| | - Feiyue Lu
- Department of Genetics, Yale University School of Medicine, 333 Cedar Street, New Haven, CT 06520, United States
| | - Andrew M Hudson
- Department of Genetics, Yale University School of Medicine, 333 Cedar Street, New Haven, CT 06520, United States
| | - Lynn Cooley
- Department of Cell Biology, Yale University School of Medicine, 333 Cedar Street, New Haven, CT 06520, United States; Department of Genetics, Yale University School of Medicine, 333 Cedar Street, New Haven, CT 06520, United States; Department of Molecular, Cellular and Developmental Biology, Yale University, 260 Prospect Street, New Haven, CT 06510, United States.
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41
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Mad linker phosphorylations control the intensity and range of the BMP-activity gradient in developing Drosophila tissues. Sci Rep 2014; 4:6927. [PMID: 25377173 PMCID: PMC4223678 DOI: 10.1038/srep06927] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2014] [Accepted: 10/17/2014] [Indexed: 01/06/2023] Open
Abstract
The BMP ligand Dpp, operates as a long range morphogen to control many important functions during Drosophila development from tissue patterning to growth. The BMP signal is transduced intracellularly via C-terminal phosphorylation of the BMP transcription factor Mad, which forms an activity gradient in developing embryonic tissues. Here we show that Cyclin dependent kinase 8 and Shaggy phosphorylate three Mad linker serines. We demonstrate that linker phosphorylations control the peak intensity and range of the BMP signal across rapidly developing embryonic tissues. Shaggy knockdown broadened the range of the BMP-activity gradient and increased high threshold target gene expression in the early embryo, while expression of a Mad linker mutant in the wing disc resulted in enhanced levels of C-terminally phosphorylated Mad, a 30% increase in wing tissue, and elevated BMP target genes. In conclusion, our results describe how Mad linker phosphorylations work to control the peak intensity and range of the BMP signal in rapidly developing Drosophila tissues.
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42
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Abstract
Flies with mutations in Atg7 or Atg8a are homozygous viable and develop to adulthood, whereas mutations in other autophagy genes, including Atg1, are homozygous lethal. Clonal analysis has been instrumental in examining the role and regulation of lethal Atg genes in many aspects of Drosophila development and survival. The generation of homozygous mutant clones in an otherwise heterozygous mutant background is possible in mitotically active tissues, and is highly beneficial in that the control cells and experimental cells are subjected to the same developmental and nutritional cues allowing for a side-by-side comparison. Several methods are now available to examine the contribution of lethal autophagy genes during Drosophila oogenesis. Here we describe how to generate a homozygous mutant germline using the FLP-DFS (dominant female sterile) technique, how to generate somatic clones, and how to induce targeted gene knockdown in the germline using RNAi.
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Affiliation(s)
- Lindsay DeVorkin
- The Genome Sciences Centre, BC Cancer Agency, Vancouver, British Columbia V5Z 1L3, Canada Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, British Columbia V5A 1S6, Canada
| | - Sharon M Gorski
- The Genome Sciences Centre, BC Cancer Agency, Vancouver, British Columbia V5Z 1L3, Canada Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, British Columbia V5A 1S6, Canada
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43
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Hudson AM, Cooley L. Methods for studying oogenesis. Methods 2014; 68:207-17. [PMID: 24440745 DOI: 10.1016/j.ymeth.2014.01.005] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2013] [Accepted: 01/02/2014] [Indexed: 12/31/2022] Open
Abstract
Drosophila oogenesis is an excellent system for the study of developmental cell biology. Active areas of research include stem cell maintenance, gamete development, pattern formation, cytoskeletal regulation, intercellular communication, intercellular transport, cell polarity, cell migration, cell death, morphogenesis, cell cycle control, and many more. The large size and relatively simple organization of egg chambers make them ideally suited for microscopy of both living and fixed whole mount tissue. A wide range of tools is available for oogenesis research. Newly available shRNA transgenic lines provide an alternative to classic loss-of-function F2 screens and clonal screens. Gene expression can be specifically controlled in either germline or somatic cells using the Gal4/UAS system. Protein trap lines provide fluorescent tags of proteins expressed at endogenous levels for live imaging and screening backgrounds. This review provides information on many available reagents and key methods for research in oogenesis.
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Affiliation(s)
- Andrew M Hudson
- Department of Genetics, Yale University School of Medicine, United States
| | - Lynn Cooley
- Department of Genetics, Yale University School of Medicine, United States; Department of Cell Biology, Yale University School of Medicine, United States; Department of Molecular, Cellular & Developmental Biology, Yale University, United States.
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Hassel C, Zhang B, Dixon M, Calvi BR. Induction of endocycles represses apoptosis independently of differentiation and predisposes cells to genome instability. Development 2013; 141:112-23. [PMID: 24284207 DOI: 10.1242/dev.098871] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The endocycle is a common developmental cell cycle variation wherein cells become polyploid through repeated genome duplication without mitosis. We previously showed that Drosophila endocycling cells repress the apoptotic cell death response to genotoxic stress. Here, we investigate whether it is differentiation or endocycle remodeling that promotes apoptotic repression. We find that when nurse and follicle cells switch into endocycles during oogenesis they repress the apoptotic response to DNA damage caused by ionizing radiation, and that this repression has been conserved in the genus Drosophila over 40 million years of evolution. Follicle cells defective for Notch signaling failed to switch into endocycles or differentiate and remained apoptotic competent. However, genetic ablation of mitosis by knockdown of Cyclin A or overexpression of fzr/Cdh1 induced follicle cell endocycles and repressed apoptosis independently of Notch signaling and differentiation. Cells recovering from these induced endocycles regained apoptotic competence, showing that repression is reversible. Recovery from fzr/Cdh1 overexpression also resulted in an error-prone mitosis with amplified centrosomes and high levels of chromosome loss and fragmentation. Our results reveal an unanticipated link between endocycles and the repression of apoptosis, with broader implications for how endocycles may contribute to genome instability and oncogenesis.
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Affiliation(s)
- Christiane Hassel
- Department of Biology, Indiana University, Bloomington, IN 47405, USA
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Jenkins VK, Timmons AK, McCall K. Diversity of cell death pathways: insight from the fly ovary. Trends Cell Biol 2013; 23:567-74. [PMID: 23968895 PMCID: PMC3839102 DOI: 10.1016/j.tcb.2013.07.005] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2013] [Revised: 07/13/2013] [Accepted: 07/15/2013] [Indexed: 01/07/2023]
Abstract
Multiple types of cell death exist including necrosis, apoptosis, and autophagic cell death. The Drosophila ovary provides a valuable model to study the diversity of cell death modalities, and we review recent progress to elucidate these pathways. At least five distinct types of cell death occur in the ovary, and we focus on two that have been studied extensively. Cell death of mid-stage egg chambers occurs through a novel caspase-dependent pathway that involves autophagy and triggers phagocytosis by surrounding somatic epithelial cells. For every egg, 15 germline nurse cells undergo developmental programmed cell death, which occurs independently of most known cell death genes. These forms of cell death are strikingly similar to cell death observed in the germlines of other organisms.
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Affiliation(s)
| | - Allison K Timmons
- Department of Biology, Boston University, 5 Cummington Mall, Boston, MA, USA
| | - Kimberly McCall
- Department of Biology, Boston University, 5 Cummington Mall, Boston, MA, USA
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Etchegaray JI, Timmons AK, Klein AP, Pritchett TL, Welch E, Meehan TL, Li C, McCall K. Draper acts through the JNK pathway to control synchronous engulfment of dying germline cells by follicular epithelial cells. Development 2012; 139:4029-39. [PMID: 22992958 DOI: 10.1242/dev.082776] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
The efficient removal of dead cells is an important process in animal development and homeostasis. Cell corpses are often engulfed by professional phagocytes such as macrophages. However, in some tissues with limited accessibility to circulating cells, engulfment is carried out by neighboring non-professional phagocytes such as epithelial cells. Here, we investigate the mechanism of corpse clearance in the Drosophila melanogaster ovary, a tissue that is closed to circulating cells. In degenerating egg chambers, dying germline cells are engulfed by the surrounding somatic follicular epithelium by unknown mechanisms. We show that the JNK pathway is activated and required in engulfing follicle cells. We find that the receptor Draper is also required in engulfing follicle cells, and activates the JNK pathway. Overexpression of Draper or the JNK pathway in follicle cells is sufficient to induce death of the underlying germline, suggesting that there is coordination between the germline and follicular epithelium to promote germline cell death. Furthermore, activation of JNK bypasses the need for Draper in engulfment. The induction of JNK and Draper in follicle cells occurs independently of caspase activity in the germline, indicating that at least two pathways are necessary to coordinate germline cell death with engulfment by the somatic epithelium.
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Abstract
Although cell death research has progressed rapidly over the two decades with emphasis on the study of apoptosis, non-apoptotic forms of cell death have recently attracted more attention. In the present short review, I will describe how this transition is occurring and emphasize the importance of investigating non-apoptotic forms of cell death as well as apoptosis to fully understand the spectrum of death in eukaryotic cells. The aim is not to list all published forms of cell death, but to indicate the necessity for a conceptual paradigm shift, so I will only introduce a limited number of cell death mechanisms.
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Affiliation(s)
- Yoshihide Tsujimoto
- Osaka University Medical School, Department of Medical Genetics, 2-2 Yamadaoka, Suita, Osaka 565-0871, Japan.
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Thomson TC, Schneemann A, Johnson J. Oocyte destruction is activated during viral infection. Genesis 2012; 50:453-65. [PMID: 22173880 DOI: 10.1002/dvg.22004] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2010] [Revised: 11/30/2011] [Accepted: 12/11/2011] [Indexed: 11/10/2022]
Abstract
Viral infection has been associated with a starvation-like state in Drosophila melanogaster. Because starvation and inhibiting TOR kinase activity in vivo result in blocked oocyte production, we hypothesized that viral infection would also result in compromised oogenesis. Wild-type flies were injected with flock house virus (FHV) and survival and embryo production were monitored. Infected flies had a dose-responsive loss of fecundity that corresponded to a global reduction in Akt/TOR signaling. Highly penetrant egg chamber destruction mid-way through oogenesis was noted and FHV coat protein was detected within developing egg chambers. As seen with in vivo TOR inhibition, oogenesis was partially rescued in loss of function discs large and merlin mutants. As expected, mutants in genes known to be involved in virus internalization and trafficking [Clathrin heavy chain (chc) and synaptotagmin] survive longer during infection. However, oogenesis was rescued only in chc mutants. This suggests that viral response mechanisms that control fly survival and egg chamber survival are separable. The genetic and signaling requirements for oocyte destruction delineated here represent a novel host-virus interaction with implications for the control of both fly and virus populations.
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Affiliation(s)
- Travis C Thomson
- Department of Obstetrics, Gynecology, and Reproductive Sciences/Division of Reproductive Endocrinology and Infertility, Yale School of Medicine, New Haven, Connecticut, USA
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McLaughlin M, Patrizio P, Kayisli U, Luk J, Thomson TC, Anderson RA, Telfer EE, Johnson J. mTOR kinase inhibition results in oocyte loss characterized by empty follicles in human ovarian cortical strips cultured in vitro. Fertil Steril 2011; 96:1154-9.e1. [PMID: 22036052 DOI: 10.1016/j.fertnstert.2011.08.040] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2011] [Revised: 07/27/2011] [Accepted: 08/22/2011] [Indexed: 01/01/2023]
Abstract
OBJECTIVE To determine whether oocyte loss is induced by mTOR kinase inhibition in human cortical strips as seen in model organisms in vivo and in vitro. DESIGN Ovarian cortex was collected at two centers and cut into small strips. Strips were cultured for 6 days with or without the mTOR inhibitor rapamycin (RAP; 100 nM). Strips were then embedded in paraffin, and serial sections were prepared. SETTING Samples were collected in general obstetric (Edinburgh), gynecologic surgery (New Haven), and fertility preservation assisted reproductive technology (ART) (New Haven) practices. PATIENT(S) Ovarian cortex collected from patients (15-34 years of age) during cesarean section (donated tissue) was removed for the purposes of fertility preservation or was prepared after oophorectomy. INTERVENTION(S) Tissue was used for research purposes only, with no subsequent patient intervention. MAIN OUTCOME MEASURE(S) Follicles were counted and assessed in each serial section. Caspase activity was monitored to determine whether mTOR inhibition activated apoptosis. RESULT(S) The RAP inclusion in cultures results in significantly fewer follicles compared with ethanol vehicle-treated controls. Furthermore, RAP treatment resulted in the induction of follicles that lacked an oocyte in any serial section (30/161 follicles vs. 1/347 ethanol vehicle-treated follicles). Caspase activity was not elevated by RAP treatment. CONCLUSION(S) mTOR inhibition results in a conserved destruction of the oocyte by adjacent granulosa cells (GC) in the absence of increased caspase activity. This model of oocyte loss is not consistent with classic apoptosis/atresia.
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Affiliation(s)
- Marie McLaughlin
- Centre for Integrative Physiology, University of Edinburgh, Edinburgh, United Kingdom
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Abstract
Apoptosis-inducing factor (AIF) is a flavin adenine dinucleotide-containing, NADH-dependent oxidoreductase residing in the mitochondrial intermembrane space whose specific enzymatic activity remains unknown. Upon an apoptotic insult, AIF undergoes proteolysis and translocates to the nucleus, where it triggers chromatin condensation and large-scale DNA degradation in a caspase-independent manner. Besides playing a key role in execution of caspase-independent cell death, AIF has emerged as a protein critical for cell survival. Analysis of in vivo phenotypes associated with AIF deficiency and defects, and identification of its mitochondrial, cytoplasmic, and nuclear partners revealed the complexity and multilevel regulation of AIF-mediated signal transduction and suggested an important role of AIF in the maintenance of mitochondrial morphology and energy metabolism. The redox activity of AIF is essential for optimal oxidative phosphorylation. Additionally, the protein is proposed to regulate the respiratory chain indirectly, through assembly and/or stabilization of complexes I and III. This review discusses accumulated data with respect to the AIF structure and outlines evidence that supports the prevalent mechanistic view on the apoptogenic actions of the flavoprotein, as well as the emerging concept of AIF as a redox sensor capable of linking NAD(H)-dependent metabolic pathways to apoptosis.
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Affiliation(s)
- Irina F Sevrioukova
- Department of Molecular Biology and Biochemistry, University of California-Irvine, CA 92697-3900, USA.
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