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Mathieu J, Huynh JR. Incomplete divisions between sister germline cells require Usp8 function. C R Biol 2024; 347:109-117. [PMID: 39345214 DOI: 10.5802/crbiol.161] [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] [Received: 05/28/2024] [Revised: 07/16/2024] [Accepted: 08/26/2024] [Indexed: 10/01/2024]
Abstract
Cytokinetic abscission is the final step of cell division, resulting in two separate daughter cells. While abscission is typically complete across most cell types, germline cells, which produce sexual gametes, do not finish cytokinesis, maintaining connections between sister cells. These connections are essential for sharing cytoplasm as they differentiate into oocyte and sperm. First, we outline the molecular events of cytokinesis during both complete and delayed abscission, highlighting the role of the ESCRT-III proteins. We then focus on recent discoveries that reveal the molecular mechanisms blocking abscission in Drosophila germline cells. The enzyme Usp8 was identified as vital for ensuring incomplete cytokinesis through the regulation of ESCRT-III ubiquitination and localization. Finally, we explore how the processes of incomplete cytokinesis could hold evolutionary importance, suggesting additional studies into choanoflagellates to comprehend the origins of multicellularity.
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Box AM, Ramesh NA, Nandakumar S, Church SJ, Prasad D, Afrakhteh A, Taichman RS, Buttitta L. Cell cycle variants during Drosophila male accessory gland development. G3 (BETHESDA, MD.) 2024; 14:jkae089. [PMID: 38683731 PMCID: PMC11228851 DOI: 10.1093/g3journal/jkae089] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/31/2024] [Revised: 01/31/2024] [Accepted: 04/09/2024] [Indexed: 05/02/2024]
Abstract
The Drosophila melanogaster male accessory gland (AG) is a functional analog of the mammalian prostate and seminal vesicles containing two secretory epithelial cell types, termed main and secondary cells. This tissue is responsible for making and secreting seminal fluid proteins and other molecules that contribute to successful reproduction. The cells of this tissue are binucleate and polyploid, due to variant cell cycles that include endomitosis and endocycling during metamorphosis. Here, we provide evidence of additional cell cycle variants in this tissue. We show that main cells of the gland are connected by ring canals that form after the penultimate mitosis, and we describe an additional post-eclosion endocycle required for gland maturation that is dependent on juvenile hormone signaling. We present evidence that the main cells of the D. melanogaster AG undergo a unique cell cycle reprogramming throughout organ development that results in step-wise cell cycle truncations culminating in cells containing two octoploid nuclei with under-replicated heterochromatin in the mature gland. We propose this tissue as a model to study developmental and hormonal temporal control of cell cycle variants in terminally differentiating tissues.
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Affiliation(s)
- Allison M Box
- Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, 1105 N. University Ave. Ann Arbor, MI 48109, USA
| | - Navyashree A Ramesh
- Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, 1105 N. University Ave. Ann Arbor, MI 48109, USA
| | - Shyama Nandakumar
- Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, 1105 N. University Ave. Ann Arbor, MI 48109, USA
| | - Samuel Jaimian Church
- Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, 1105 N. University Ave. Ann Arbor, MI 48109, USA
| | - Dilan Prasad
- Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, 1105 N. University Ave. Ann Arbor, MI 48109, USA
| | - Ariana Afrakhteh
- Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, 1105 N. University Ave. Ann Arbor, MI 48109, USA
| | - Russell S Taichman
- Department of Periodontology, School of Dentistry, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Laura Buttitta
- Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, 1105 N. University Ave. Ann Arbor, MI 48109, USA
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Rujano MA, Briand D, Ðelić B, Marc J, Spéder P. An interplay between cellular growth and atypical fusion defines morphogenesis of a modular glial niche in Drosophila. Nat Commun 2022; 13:4999. [PMID: 36008397 PMCID: PMC9411534 DOI: 10.1038/s41467-022-32685-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2021] [Accepted: 08/10/2022] [Indexed: 11/16/2022] Open
Abstract
Neural stem cells (NSCs) live in an intricate cellular microenvironment supporting their activity, the niche. Whilst shape and function are inseparable, the morphogenetic aspects of niche development are poorly understood. Here, we use the formation of a glial niche to investigate acquisition of architectural complexity. Cortex glia (CG) in Drosophila regulate neurogenesis and build a reticular structure around NSCs. We first show that individual CG cells grow tremendously to ensheath several NSC lineages, employing elaborate proliferative mechanisms which convert these cells into syncytia rich in cytoplasmic bridges. CG syncytia further undergo homotypic cell-cell fusion, using defined cell surface receptors and actin regulators. Cellular exchange is however dynamic in space and time. This atypical cell fusion remodels cellular borders, restructuring the CG syncytia. Ultimately, combined growth and fusion builds the multi-level architecture of the niche, and creates a modular, spatial partition of the NSC population. Our findings provide insights into how a niche forms and organises while developing intimate contacts with a stem cell population.
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Affiliation(s)
| | | | - Bojana Ðelić
- Institut Pasteur, CNRS UMR3738, Paris, France
- Institut de Biologie de l'Ecole Normale Supérieure (IBENS), Cell Division and Neurogenesis, Ecole Normale Supérieure, CNRS, Inserm, PSL Université Paris, Paris, France
| | - Julie Marc
- Institut Pasteur, CNRS UMR3738, Paris, France
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Alsous JI, Rozman J, Marmion RA, Košmrlj A, Shvartsman SY. Clonal dominance in excitable cell networks. NATURE PHYSICS 2021; 17:1391-1395. [PMID: 35242199 PMCID: PMC8887698 DOI: 10.1038/s41567-021-01383-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
Clonal dominance arises when the descendants (clones) of one or a few founder cells contribute disproportionally to the final structure during collective growth [1-8]. In contexts such as bacterial growth, tumorigenesis, and stem cell reprogramming [2-4], this phenomenon is often attributed to pre-existing propensities for dominance, while in stem cell homeostasis, neutral drift dynamics are invoked [5,6]. The mechanistic origin of clonal dominance during development, where it is increasingly documented [1,6-8], is less understood. Here, we investigate this phenomenon in the Drosophila melanogaster follicle epithelium, a system in which the joint growth dynamics of cell lineage trees can be reconstructed. We demonstrate that clonal dominance can emerge spontaneously, in the absence of pre-existing biases, as a collective property of evolving excitable networks through coupling of divisions among connected cells. Similar mechanisms have been identified in forest fires and evolving opinion networks [9-11]; we show that the spatial coupling of excitable units explains a critical feature of the development of the organism, with implications for tissue organization and dynamics [1,12,13].
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Affiliation(s)
- Jasmin Imran Alsous
- Flatiron Institute, Simons Foundation, New York, NY 10010, USA
- These authors contributed equally
| | - Jan Rozman
- Jožef Stefan Institute, Ljubljana 1000, Slovenia
- Faculty of Mathematics and Physics, University of Ljubljana, Ljubljana 1000, Slovenia
- These authors contributed equally
| | - Robert A. Marmion
- The Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ 08544, USA
| | - Andrej Košmrlj
- Department of Mechanical and Aerospace Engineering, Princeton University, Princeton, NJ 08544, USA
| | - Stanislav Y. Shvartsman
- Flatiron Institute, Simons Foundation, New York, NY 10010, USA
- The Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ 08544, USA
- Department of Molecular Biology, Princeton University, Princeton, NJ 08544, USA
- Corresponding author ()
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Drosophila Atg9 regulates the actin cytoskeleton via interactions with profilin and Ena. Cell Death Differ 2019; 27:1677-1692. [PMID: 31740789 DOI: 10.1038/s41418-019-0452-0] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2018] [Revised: 10/25/2019] [Accepted: 10/29/2019] [Indexed: 12/16/2022] Open
Abstract
Autophagy ensures the turnover of cytoplasm and requires the coordinated action of Atg proteins, some of which also have moonlighting functions in higher eukaryotes. Here we show that the transmembrane protein Atg9 is required for female fertility, and its loss leads to defects in actin cytoskeleton organization in the ovary and enhances filopodia formation in neurons in Drosophila. Atg9 localizes to the plasma membrane anchor points of actin cables and is also important for the integrity of the cortical actin network. Of note, such phenotypes are not seen in other Atg mutants, suggesting that these are independent of autophagy defects. Mechanistically, we identify the known actin regulators profilin and Ena/VASP as novel binding partners of Atg9 based on microscopy, biochemical, and genetic interactions. Accordingly, the localization of both profilin and Ena depends on Atg9. Taken together, our data identify a new and unexpected role for Atg9 in actin cytoskeleton regulation.
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Identification of Novel Regulators of the JAK/STAT Signaling Pathway that Control Border Cell Migration in the Drosophila Ovary. G3-GENES GENOMES GENETICS 2016; 6:1991-2002. [PMID: 27175018 PMCID: PMC4938652 DOI: 10.1534/g3.116.028100] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
The Janus Kinase/Signal Transducer and Activator of Transcription (JAK/STAT) signaling pathway is an essential regulator of cell migration both in mammals and fruit flies. Cell migration is required for normal embryonic development and immune response but can also lead to detrimental outcomes, such as tumor metastasis. A cluster of cells termed “border cells” in the Drosophila ovary provides an excellent example of a collective cell migration, in which two different cell types coordinate their movements. Border cells arise within the follicular epithelium and are required to invade the neighboring cells and migrate to the oocyte to contribute to a fertilizable egg. Multiple components of the STAT signaling pathway are required during border cell specification and migration; however, the functions and identities of other potential regulators of the pathway during these processes are not yet known. To find new components of the pathway that govern cell invasiveness, we knocked down 48 predicted STAT modulators using RNAi expression in follicle cells, and assayed defective cell movement. We have shown that seven of these regulators are involved in either border cell specification or migration. Examination of the epistatic relationship between candidate genes and Stat92E reveals that the products of two genes, Protein tyrosine phosphatase 61F (Ptp61F) and brahma (brm), interact with Stat92E during both border cell specification and migration.
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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: 83] [Impact Index Per Article: 7.5] [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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