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Price KL, Tharakan DM, Salvenmoser W, Ayers K, Mah J, Dunn C, Hobmayer B, Cooley L. Examination of germline and somatic intercellular bridges in Hydra vulgaris reveals insights into the evolutionarily conserved mechanism of intercellular bridge formation. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2025:2025.02.19.639158. [PMID: 40027827 PMCID: PMC11870534 DOI: 10.1101/2025.02.19.639158] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 03/05/2025]
Abstract
Incomplete cytokinesis results in the formation of stable intercellular bridges that have been extensively studied in bilaterians, where they play essential roles in cell-cell communication and coordination of differentiation. However, little is known about their structure and molecular composition in non-bilaterian animals. This study characterizes germline and somatic intercellular bridges in the cnidarian Hydra vulgaris, providing insights into their evolutionary origins and functional significance. We identified key conserved components, including KIF23, F-actin, and phosphotyrosine. Notably, we observed microtubule localization within Hydra ring canals, suggesting previously unrecognized functions for this cytoskeletal component in intercellular bridge formation. Bioinformatic analyses confirmed the conserved expression of Kif23 and suggested its role as a molecular marker for identifying ring canal-associated components. EdU incorporation during DNA replication demonstrated that cells connected by ring canals exhibit synchronized cell cycles, which may be critical for the coordination of division and differentiation. Our findings reveal that the molecular and structural features of intercellular bridges in Hydra are conserved across evolutionary lineages, highlighting their ancient origins and functional significance in cellular connectivity. The presence of synchronized cell cycles in ring canal-connected cells underscores their role in promoting coordinated cellular behaviors, processes fundamental to multicellular organization. This study provides new perspectives on the evolution of incomplete cytokinesis and establishes a framework for comparative investigations into the diversity and conservation of intercellular bridge mechanisms across metazoans.
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Affiliation(s)
- Kari L. Price
- Department of Genetics, Yale University School of Medicine, New Haven, CT, USA
- UC Davis Comprehensive Cancer Center, Sacramento, CA, USA
| | - Dyuthi M. Tharakan
- Department of Genetics, Yale University School of Medicine, New Haven, CT, USA
- UCLA David Geffen School of Medicine, Los Angeles, CA, USA
| | - Willi Salvenmoser
- Institute of Zoology and Centre for Molecular Biosciences, University of Innsbruck, Innsbruck, Austria
| | - Kathleen Ayers
- Department of Genetics, Yale University School of Medicine, New Haven, CT, USA
| | - Jasmine Mah
- Department of Ecology and Evolutionary Biology, Yale University, New Haven, CT, USA
| | - Casey Dunn
- Department of Ecology and Evolutionary Biology, Yale University, New Haven, CT, USA
| | - Bert Hobmayer
- Institute of Zoology and Centre for Molecular Biosciences, University of Innsbruck, Innsbruck, Austria
| | - Lynn Cooley
- Department of Genetics, Yale University School of Medicine, New Haven, CT, USA
- Department of Cell Biology, Yale University School of Medicine, New Haven, CT, USA
- Department of Molecular, Cellular, and Developmental Biology, Yale University, New Haven, CT, USA
- Lead contact
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Beachum AN, Hinnant TD, Williams AE, Powell AM, Ables ET. β-importin Tnpo-SR promotes germline stem cell maintenance and oocyte differentiation in female Drosophila. Dev Biol 2023; 494:1-12. [PMID: 36450333 PMCID: PMC9870978 DOI: 10.1016/j.ydbio.2022.11.006] [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: 09/22/2021] [Revised: 11/09/2022] [Accepted: 11/21/2022] [Indexed: 11/29/2022]
Abstract
Germ cell development requires interplay between factors that balance cell fate and division. Early in their development, germ cells in many organisms divide mitotically with incomplete cytokinesis. Key regulatory events then lead to the specification of mature gametes, marked by the switch to a meiotic cell cycle program. Though the regulation of germ cell proliferation and meiosis are well understood, how these events are coordinated during development remains incompletely described. Originally characterized in their role as nucleo-cytoplasmic shuttling proteins, β-importins exhibit diverse functions during male and female gametogenesis. Here, we describe novel, distinct roles for the β-importin, Transportin-Serine/Arginine rich (Tnpo-SR), as a regulator of the mitosis to meiosis transition in the Drosophila ovary. We find that Tnpo-SR is necessary for germline stem cell (GSC) establishment and self-renewal, likely by controlling the response of GSCs to bone morphogenetic proteins. Depletion of Tnpo-SR results in germ cell counting defects and loss of oocyte identity. We show that in the absence of Tnpo-SR, proteins typically suppressed in germ cells when they exit mitosis fail to be down-regulated, and oocyte-specific factors fail to accumulate. Together, these findings provide new insight into the balance between germ cell division and differentiation and identify novel roles for β-importins in germ cell development.
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Affiliation(s)
- Allison N Beachum
- Department of Biology, East Carolina University, Greenville, NC, 27858, USA
| | - Taylor D Hinnant
- Department of Biology, East Carolina University, Greenville, NC, 27858, USA
| | - Anna E Williams
- Department of Biology, East Carolina University, Greenville, NC, 27858, USA
| | - Amanda M Powell
- Department of Biology, East Carolina University, Greenville, NC, 27858, USA
| | - Elizabeth T Ables
- Department of Biology, East Carolina University, Greenville, NC, 27858, USA.
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Precursor RNA processing 3 is required for male fertility, and germline stem cell self-renewal and differentiation via regulating spliceosome function in Drosophila testes. Sci Rep 2019; 9:9988. [PMID: 31292463 PMCID: PMC6620278 DOI: 10.1038/s41598-019-46419-x] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2018] [Accepted: 06/28/2019] [Indexed: 11/17/2022] Open
Abstract
The nuclear pre-mRNA spliceosome is a large complex containing five small nuclear ribonucleoprotein particles (snRNPs) and many splicing factors. Messenger RNAs (mRNAs) are generated from pre-mRNAs by the process of RNA splicing, which is conserved in eukaryotes. Precursor RNA processing 3 (Prp3) is a U4/U6-associated snRNP whose function remains largely unknown. In the present study, using genetic manipulation of a Drosophila melanogaster testis model, we demonstrated that Prp3 is essential for male fertility in Drosophila. Prp3 deficiency in germline stem cells (GSCs) and early cyst cells resulted in abnormal structure of testes and maintenance defects of GSCs and cyst stem cells. Knockdown of Prp3 in spermatogonia and early cyst cells mediated tumor formation caused by differentiation defects. Using an in vitro assay, knockdown of Prp3 decreased proliferation and increased cell death, and controlled the spliceosome function via regulating spliceosome subunits expression in Drosophila S2 cells. We also identified two other splicing factors in the Prp complex (Prp19 and Prp8), which mimicked the phenotype of Prp3 in the Drosophila stem cell niche. Our results revealed a significant role of precursor RNA processing factors in male testes, indicating that Prp3, a key spliceosome component in the Prp complex, is essential for male fertility, and germline stem cell self-renewal and differentiation, via regulating the spliceosome function in Drosophila testes.
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Carter TY, Gadwala S, Chougule AB, Bui APN, Sanders AC, Chaerkady R, Cormier N, Cole RN, Thomas JH. Actomyosin contraction during cellularization is regulated in part by Src64 control of Actin 5C protein levels. Genesis 2019; 57:e23297. [PMID: 30974046 DOI: 10.1002/dvg.23297] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2019] [Accepted: 03/27/2019] [Indexed: 11/09/2022]
Abstract
Src64 is required for actomyosin contraction during cellularization of the Drosophila embryonic blastoderm. The mechanism of actomyosin ring constriction is poorly understood even though a number of cytoskeletal regulators have been implicated in the assembly, organization, and contraction of these microfilament rings. How these cytoskeletal processes are regulated during development is even less well understood. To investigate the role of Src64 as an upstream regulator of actomyosin contraction, we conducted a proteomics screen to identify proteins whose expression levels are controlled by src64. Global levels of actin are reduced in src64 mutant embryos. Furthermore, we show that reduction of the actin isoform Actin 5C causes defects in actomyosin contraction during cellularization similar to those caused by src64 mutation, indicating that a relatively high level of Actin 5C is required for normal actomyosin contraction and furrow canal structure. However, reduction of Actin 5C levels only slows down actomyosin ring constriction rather than preventing it, suggesting that src64 acts not only to modulate actin levels, but also to regulate the actomyosin cytoskeleton by other means.
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Affiliation(s)
- Tammy Y Carter
- Department of Cell Biology and Biochemistry, Texas Tech University Health Sciences Center, Lubbock, Texas
| | - Swetha Gadwala
- Department of Cell Biology and Biochemistry, Texas Tech University Health Sciences Center, Lubbock, Texas
| | - Ashish B Chougule
- Department of Cell Biology and Biochemistry, Texas Tech University Health Sciences Center, Lubbock, Texas
| | - Anh P N Bui
- Department of Cell Biology and Biochemistry, Texas Tech University Health Sciences Center, Lubbock, Texas
| | - Alex C Sanders
- Department of Cell Biology and Biochemistry, Texas Tech University Health Sciences Center, Lubbock, Texas
| | - Raghothama Chaerkady
- Department of Biological Chemistry, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Nathaly Cormier
- Department of Cell Biology and Biochemistry, Texas Tech University Health Sciences Center, Lubbock, Texas
| | - Robert N Cole
- Department of Biological Chemistry, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Jeffrey H Thomas
- Department of Cell Biology and Biochemistry, Texas Tech University Health Sciences Center, Lubbock, Texas
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Lenhart KF, Capozzoli B, Warrick GSD, DiNardo S. Diminished Jak/STAT Signaling Causes Early-Onset Aging Defects in Stem Cell Cytokinesis. Curr Biol 2019; 29:256-267.e3. [PMID: 30612906 DOI: 10.1016/j.cub.2018.11.064] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2018] [Revised: 11/12/2018] [Accepted: 11/28/2018] [Indexed: 01/09/2023]
Abstract
Tissue renewal becomes compromised with age. Although defects in niche and stem cell behavior have been implicated in promoting age-related decline, the causes of early-onset aging defects are unknown. We have identified an early consequence of aging in germline stem cells (GSCs) in the Drosophila testis. Aging disrupts the unique program of GSC cytokinesis, with GSCs failing to abscise from their daughter cells. Abscission failure significantly disrupts both self-renewal and the generation of differentiating germ cells. Extensive live imaging and genetic analyses show that abscission failure is due to inappropriate retention of F-actin at the intercellular bridges between GSC-daughter cells. Furthermore, F-actin is regulated by the Jak/STAT pathway-increasing or decreasing pathway activity can rescue or exacerbate the age-induced abscission defect, respectively. Even subtle decreases to STAT activity are sufficient to precociously age young GSCs and induce abscission failure. Thus, this work has identified the earliest age-related defect in GSCs and has revealed a unique role for an established niche signaling pathway in controlling stem cell cytokinesis and in regulating stem cell behavior with age.
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Affiliation(s)
- Kari F Lenhart
- Department of Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA; Department of Biology, Drexel University, Philadelphia, PA 19104, USA.
| | - Benjamin Capozzoli
- Department of Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Gwen S D Warrick
- Department of Biology, Drexel University, Philadelphia, PA 19104, USA
| | - Stephen DiNardo
- Department of Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA; Institute for Regenerative Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA.
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Subcellular Specialization and Organelle Behavior in Germ Cells. Genetics 2018; 208:19-51. [PMID: 29301947 DOI: 10.1534/genetics.117.300184] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2016] [Accepted: 08/17/2017] [Indexed: 11/18/2022] Open
Abstract
Gametes, eggs and sperm, are the highly specialized cell types on which the development of new life solely depends. Although all cells share essential organelles, such as the ER (endoplasmic reticulum), Golgi, mitochondria, and centrosomes, germ cells display unique regulation and behavior of organelles during gametogenesis. These germ cell-specific functions of organelles serve critical roles in successful gamete production. In this chapter, I will review the behaviors and roles of organelles during germ cell differentiation.
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Zhang Y, Yu JC, Jiang T, Fernandez-Gonzalez R, Harris TJC. Collision of Expanding Actin Caps with Actomyosin Borders for Cortical Bending and Mitotic Rounding in a Syncytium. Dev Cell 2018; 45:551-564.e4. [PMID: 29804877 DOI: 10.1016/j.devcel.2018.04.024] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2017] [Revised: 03/30/2018] [Accepted: 04/25/2018] [Indexed: 10/24/2022]
Abstract
The early Drosophila embryo is a large syncytial cell that compartmentalizes mitotic spindles with furrows. Before furrow ingression, an Arp2/3 actin cap forms above each nucleus and is encircled by actomyosin. We investigated how these networks transform a flat cortex into a honeycomb-like compartmental array. The growing caps circularize and ingress upon meeting their actomyosin borders, which become the furrow base. Genetic perturbations indicate that the caps physically displace their borders and, reciprocally, that the borders resist and circularize their caps. These interactions create an actomyosin cortex arrayed with circular caps. The Rac-GEF Sponge, Rac-GTP, Arp3, and actin coat the caps as a growing material that can drive cortical bending for initial furrow ingression. Additionally, laser ablations indicate that actomyosin contraction squeezes the cytoplasm, producing counterforces that swell the caps. Thus, Arp2/3 caps form clearances of the actomyosin cortex and control buckling and swelling of these clearances for metaphase compartmentalization.
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Affiliation(s)
- Yixie Zhang
- Department of Cell & Systems Biology, University of Toronto, Toronto, ON M5S 3G5, Canada
| | - Jessica C Yu
- Institute of Biomaterials and Biomedical Engineering, University of Toronto, Toronto, ON M5S 3G9, Canada
| | - Tao Jiang
- Department of Cell & Systems Biology, University of Toronto, Toronto, ON M5S 3G5, Canada
| | - Rodrigo Fernandez-Gonzalez
- Department of Cell & Systems Biology, University of Toronto, Toronto, ON M5S 3G5, Canada; Institute of Biomaterials and Biomedical Engineering, University of Toronto, Toronto, ON M5S 3G9, Canada; Ted Rogers Centre for Heart Research, University of Toronto, Toronto, ON M5G 1M1, Canada; Developmental and Stem Cell Biology Program, The Hospital for Sick Children, Toronto, ON M5G 1X8, Canada
| | - Tony J C Harris
- Department of Cell & Systems Biology, University of Toronto, Toronto, ON M5S 3G5, Canada.
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Thieleke-Matos C, Osório DS, Carvalho AX, Morais-de-Sá E. Emerging Mechanisms and Roles for Asymmetric Cytokinesis. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2017; 332:297-345. [PMID: 28526136 DOI: 10.1016/bs.ircmb.2017.01.004] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Cytokinesis completes cell division by physically separating the contents of the mother cell between the two daughter cells. This event requires the highly coordinated reorganization of the cytoskeleton within a precise window of time to ensure faithful genomic segregation. In addition, recent progress in the field highlighted the importance of cytokinesis in providing particularly important cues in the context of multicellular tissues. The organization of the cytokinetic machinery and the asymmetric localization or inheritance of the midbody remnants is critical to define the spatial distribution of mechanical and biochemical signals. After a brief overview of the conserved steps of animal cytokinesis, we review the mechanisms controlling polarized cytokinesis focusing on the challenges of epithelial cytokinesis. Finally, we discuss the significance of these asymmetries in defining embryonic body axes, determining cell fate, and ensuring the correct propagation of epithelial organization during proliferation.
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Affiliation(s)
- C Thieleke-Matos
- i3S-Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal; Cell Division and Genomic stability, IBMC, Instituto de Biologia Molecular e Celular, and i3S, Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal
| | - D S Osório
- i3S-Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal; Cytoskeletal Dynamics, IBMC, Instituto de Biologia Molecular e Celular, and i3S, Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal
| | - A X Carvalho
- i3S-Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal; Cytoskeletal Dynamics, IBMC, Instituto de Biologia Molecular e Celular, and i3S, Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal
| | - E Morais-de-Sá
- i3S-Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal; Cell Division and Genomic stability, IBMC, Instituto de Biologia Molecular e Celular, and i3S, Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal.
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Partial Functional Diversification of Drosophila melanogaster Septin Genes Sep2 and Sep5. G3-GENES GENOMES GENETICS 2016; 6:1947-57. [PMID: 27172205 PMCID: PMC4938648 DOI: 10.1534/g3.116.028886] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
The septin family of hetero-oligomeric complex-forming proteins can be divided into subgroups, and subgroup members are interchangeable at specific positions in the septin complex. Drosophila melanogaster has five septin genes, including the two SEPT6 subgroup members Sep2 and Sep5. We previously found that Sep2 has a unique function in oogenesis, which is not performed by Sep5. Here, we find that Sep2 is uniquely required for follicle cell encapsulation of female germline cysts, and that Sep2 and Sep5 are redundant for follicle cell proliferation. The five D. melanogaster septins localize similarly in oogenesis, including as rings flanking the germline ring canals. Pnut fails to localize in Sep5; Sep2 double mutant follicle cells, indicating that septin complexes fail to form in the absence of both Sep2 and Sep5. We also find that mutations in septins enhance the mutant phenotype of bazooka, a key component in the establishment of cell polarity, suggesting a link between septin function and cell polarity. Overall, this work suggests that Sep5 has undergone partial loss of ancestral protein function, and demonstrates redundant and unique functions of septins.
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Eikenes ÅH, Malerød L, Lie-Jensen A, Wegner CS, Brech A, Liestøl K, Stenmark H, Haglund K. Src64 controls a novel actin network required for proper ring canal formation in the Drosophila male germline. J Cell Sci 2015. [DOI: 10.1242/jcs.184010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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