1
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Warder BN, Nelson KA, Sui J, Anllo L, DiNardo S. An actomyosin network organizes niche morphology and responds to feedback from recruited stem cells. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2023.09.08.556877. [PMID: 38746236 PMCID: PMC11092431 DOI: 10.1101/2023.09.08.556877] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2024]
Abstract
Stem cells often rely on signals from a niche, which in many tissues adopts a precise morphology. What remains elusive is how niches are formed, and how morphology impacts function. To address this, we leverage the Drosophila gonadal niche, which affords genetic tractability and live-imaging. We have previously shown mechanisms dictating niche cell migration to their appropriate position within the gonad, and the resultant consequences on niche function. Here, we show that once positioned, niche cells robustly polarize filamentous actin (F-actin) and Non-muscle Myosin II (MyoII) towards neighboring germ cells. Actomyosin tension along the niche periphery generates a highly reproducible smoothened contour. Without contractility, niches are misshapen and exhibit defects in their ability to regulate germline stem cell behavior. We additionally show that germ cells aid in polarizing MyoII within niche cells, and that extrinsic input is required for niche morphogenesis and function. Our work reveals a feedback mechanism where stem cells shape the niche that guides their behavior.
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2
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Hof-Michel S, Cigoja L, Huhn S, Bökel C. Rel governs loser elimination during stem cell competition in the Drosophila testis. Eur J Cell Biol 2024; 103:151375. [PMID: 37995529 DOI: 10.1016/j.ejcb.2023.151375] [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: 04/21/2023] [Revised: 11/16/2023] [Accepted: 11/16/2023] [Indexed: 11/25/2023] Open
Abstract
In the Drosophila testis, a group of stromal cells termed hub provides multiple niche signals for the surrounding germline and somatic stem cells. Stem cells of both populations compete for physical retention in the niche, and clones unable to transduce any one niche signal are rapidly eliminated from the stem cell pool by differentiation. We have mapped the transcriptomes of isolated somatic cyst stem cells and differentiated cyst cells, and found that the stem cells but not their differentiated progeny exhibit the signature of an innate immune response including the NF-κB transcription factor Relish (Rel). Related signalling pathways had previously implicated in cell competition in larval epithelia, prompting the question of whether NF-κB signalling was, despite the clear differences between the two competition scenarios, also involved in stem cell competition in the testis. Here we show i) that in the testis Rel is dispensable for stemness, ii) that loss of Rel or the upstream receptor Toll suppresses loser elimination following a variety of different triggers used to induce loser fate, and iii) that clonal Rel activation is sufficient for the displacement of neutral or winner cells from the niche, even if these cells otherwise retain stem cell properties.
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Affiliation(s)
- Silvana Hof-Michel
- Dept. of Developmental Genetics, Philipps University Marburg, Karl-von-Frisch-Str. 8, 35043 Marburg, Germany
| | - Ljubinka Cigoja
- Dept. of Developmental Genetics, Philipps University Marburg, Karl-von-Frisch-Str. 8, 35043 Marburg, Germany
| | - Sabina Huhn
- Dept. of Developmental Genetics, Philipps University Marburg, Karl-von-Frisch-Str. 8, 35043 Marburg, Germany
| | - Christian Bökel
- Core Facility Confocal and Multiphoton Microscopy, Universität Ulm, Albert-Einstein-Allee 11, 89081 Ulm, Germany.
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3
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Eslahi M, Nematbakhsh N, Dastmalchi N, Teimourian S, Safaralizadeh R. Signaling Pathways in Drosophila gonadal Stem Cells. Curr Stem Cell Res Ther 2024; 19:154-165. [PMID: 36788694 DOI: 10.2174/1574888x18666230213144531] [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: 06/21/2022] [Revised: 12/07/2022] [Accepted: 12/22/2022] [Indexed: 02/16/2023]
Abstract
The stem cells' ability to divide asymmetrically to produce differentiating and self-renewing daughter cells is crucial to maintain tissue homeostasis and development. Stem cell maintenance and differentiation rely on their regulatory microenvironment termed 'niches'. The mechanisms of the signal transduction pathways initiated from the niche, regulation of stem cell maintenance and differentiation were quite challenging to study. The knowledge gained from the study of Drosophila melanogaster testis and ovary helped develop our understanding of stem cell/niche interactions and signal pathways related to the regulatory mechanisms in maintaining homeostasis of adult tissue. In this review, we discuss the role of signaling pathways in Drosophila gonadal stem cell regeneration, competition, differentiation, dedifferentiation, proliferation, and fate determination. Furthermore, we present the current knowledge on how these signaling pathways are implicated in cancer, and how they contribute as potential candidates for effective cancer treatment.
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Affiliation(s)
- Maede Eslahi
- Department of Animal Biology, Faculty of Natural Sciences, University of Tabriz, Tabriz, Iran
| | - Negin Nematbakhsh
- Department of Animal Biology, Faculty of Natural Sciences, University of Tabriz, Tabriz, Iran
| | - Narges Dastmalchi
- Department of Biology, University College of Nabi Akram, Tabriz, Iran
| | - Shahram Teimourian
- Department of Medical Genetics, School of Medicine, Iran University of Medical Sciences (IUMS), Tehran, Iran
| | - Reza Safaralizadeh
- Department of Animal Biology, Faculty of Natural Sciences, University of Tabriz, Tabriz, Iran
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4
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Sreejith P, Kim C. Lin28 is Required for Single Niche Development in the Drosophila Male Gonad. Dev Reprod 2023; 27:221-226. [PMID: 38292237 PMCID: PMC10824566 DOI: 10.12717/dr.2023.27.4.221] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2023] [Revised: 10/22/2023] [Accepted: 11/23/2023] [Indexed: 02/01/2024]
Abstract
A stem cell niche provides an environment that governs stem cell maintenance and division. Thus, the development of a proper niche is of prime importance to stem cell behaviors. Mechanisms of niche development are beginning to be revealed in the Drosophila male gonad. Niche cells are initially dispersed throughout the gonad, then assemble at its apical tip through the anterior migration of posteriorly located niche cells. The molecular mechanisms of this migration and assembly are still poorly understood. Here we show evidence suggesting that Lin28, an RNA-binding protein and regulator of let7 genesis, might be an intrinsic factor for the anterior migration of niche cells. We found that a dispersed, ectopic niche, a phenotype observed with anterior migration defects, occurs in lin28 mutant gonads. This phenotype is rescued by expression of lin28 in the niche cells. These findings suggest that Lin28 might be required for the anterior migration of niche cells.
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Affiliation(s)
- Perinthottathil Sreejith
- Department of Biomedical Genetics,
University of Rochester Medical Center, Rochester,
NY 14642, USA
| | - Changsoo Kim
- School of Biological Sciences and
Technology, Chonnam National University, Gwangju
61186, Korea
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5
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Yildirim K, van Nierop Y Sanchez P, Lohmann I. Analysis of Bub3 and Nup75 in the Drosophila male germline lineage. Cells Dev 2023; 175:203863. [PMID: 37286104 DOI: 10.1016/j.cdev.2023.203863] [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: 01/31/2023] [Revised: 05/04/2023] [Accepted: 06/01/2023] [Indexed: 06/09/2023]
Abstract
Extensive communication at the stem cell-niche interface and asymmetric stem cell division is key for the homeostasis of the Drosophila male germline stem cell system. To improve our understanding of these processes, we analysed the function of the mitotic checkpoint complex (MCC) component Bub3 and the nucleoporin Nup75, a component of the nuclear pore complex realizing the transport of signalling effector molecules to the nucleus, in the Drosophila testis. By lineage-specific interference, we found that the two genes control germline development and maintenance. Bub3 is continuously required in the germline, as its loss results in the beginning in an over-proliferation of early germ cells and later on in loss of the germline. The absence of the germline lineage in such testes has dramatic cell non-autonomous consequences, as cells co-expressing markers of hub and somatic cyst cell fates accumulate and populate in extreme cases the whole testis. Our analysis of Nups showed that some of them are critical for lineage maintenance, as their depletion results in the loss of the affected lineage. In contrast, Nup75 plays a role in controlling proliferation of early germ cells but not differentiating spermatogonia and seems to be involved in keeping hub cells quiescent. In sum, our analysis shows that Bub3 and Nup75 are required for male germline development and maintenance.
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Affiliation(s)
- Kerem Yildirim
- Heidelberg University, Centre for Organismal Studies (COS) Heidelberg, Department of Developmental Biology and Cell Networks - Cluster of Excellence, Heidelberg, Germany
| | - Patrick van Nierop Y Sanchez
- Heidelberg University, Centre for Organismal Studies (COS) Heidelberg, Department of Developmental Biology and Cell Networks - Cluster of Excellence, Heidelberg, Germany
| | - Ingrid Lohmann
- Heidelberg University, Centre for Organismal Studies (COS) Heidelberg, Department of Developmental Biology and Cell Networks - Cluster of Excellence, Heidelberg, Germany.
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6
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Price KL, Tharakan DM, Cooley L. Evolutionarily conserved midbody remodeling precedes ring canal formation during gametogenesis. Dev Cell 2023; 58:474-488.e5. [PMID: 36898376 PMCID: PMC10059090 DOI: 10.1016/j.devcel.2023.02.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2022] [Revised: 11/18/2022] [Accepted: 02/10/2023] [Indexed: 03/12/2023]
Abstract
How canonical cytokinesis is altered during germ cell division to produce stable intercellular bridges, called "ring canals," is poorly understood. Here, using time-lapse imaging in Drosophila, we observe that ring canal formation occurs through extensive remodeling of the germ cell midbody, a structure classically associated with its function in recruiting abscission-regulating proteins in complete cytokinesis. Germ cell midbody cores reorganize and join the midbody ring rather than being discarded, and this transition is accompanied by changes in centralspindlin dynamics. The midbody-to-ring canal transformation is conserved in the Drosophila male and female germlines and during mouse and Hydra spermatogenesis. In Drosophila, ring canal formation depends on Citron kinase function to stabilize the midbody, similar to its role during somatic cell cytokinesis. Our results provide important insights into the broader functions of incomplete cytokinesis events across biological systems, such as those observed during development and disease states.
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Affiliation(s)
- Kari L Price
- Department of Genetics, Yale University School of Medicine, New Haven, CT, USA
| | - Dyuthi M Tharakan
- Department of Genetics, Yale University School of Medicine, New Haven, CT, USA
| | - 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 & Developmental Biology, Yale University, New Haven, CT, USA.
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7
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Mues N, Hammer K, Leatherman J. Pvr regulates cyst stem cell division in the Drosophila testis niche, and has functions distinct from Egfr. Cells Dev 2023; 173:203822. [PMID: 36400422 PMCID: PMC10033353 DOI: 10.1016/j.cdev.2022.203822] [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: 06/13/2022] [Revised: 11/07/2022] [Accepted: 11/11/2022] [Indexed: 11/17/2022]
Abstract
Regulation of the rate of stem cell division is one of the key determinants of the abundance of differentiating progeny in stem cell-supported tissues, and mis-regulation can lead to tumorigenesis. The well-studied Drosophila testis niche is an excellent model system to study the regulation of stem cell division in vivo. This niche supports two stem cell populations-the germline stem cells (GSCs) and cyst stem cells (CySCs), which cluster around a group of cells called the hub. The differentiating cells of these two stem cell populations cooperate together to produce sperm. Signal transduction initiated by the epidermal growth factor receptor (Egfr) is a key regulatory pathway in the cyst lineage, and much of the study of this stem cell population has centered around understanding the complexities of the requirements for Egfr signaling. We examined another receptor tyrosine kinase, Pvr, the sole Drosophila PDGF/VEGF homolog, and found that it accumulates in the cyst lineage cells of the testis, while its ligand Pvf1 accumulates in the hub. Pvr inhibition caused a reduction in both CySC numbers and the proportion of CySCs in S phase, similar to Egfr inhibition. However, testes with Pvr inhibition exhibited a low-penetrance non-autonomous germ cell differentiation defect distinct from that observed with Egfr inhibition. Cyst cells with constitutively activated Pvr failed to support germ cell differentiation, as observed with constitutively activated Egfr. However, constitutively activated Pvr promoted tumorous accumulation of cyst cells outside of the niche, a phenotype not observed with constitutively activated Egfr. Thus, Egfr and Pvr have some receptor-specific functions and some shared functions in the cyst lineage cells of the testis.
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Affiliation(s)
- Nastaran Mues
- School of Biological Sciences, University of Northern Colorado, Greeley, CO, United States
| | - Kenneth Hammer
- School of Biological Sciences, University of Northern Colorado, Greeley, CO, United States
| | - Judith Leatherman
- School of Biological Sciences, University of Northern Colorado, Greeley, CO, United States.
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8
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Solovieva T, Wilson V, Stern CD. A niche for axial stem cells - A cellular perspective in amniotes. Dev Biol 2022; 490:13-21. [PMID: 35779606 PMCID: PMC10497457 DOI: 10.1016/j.ydbio.2022.06.015] [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: 09/16/2021] [Revised: 05/19/2022] [Accepted: 06/25/2022] [Indexed: 11/24/2022]
Abstract
The head-tail axis in birds and mammals develops from a growth zone in the tail-end, which contains the node. This growth zone then forms the tailbud. Labelling experiments have shown that while many cells leave the node and tailbud to contribute to axial (notochord, floorplate) and paraxial (somite) structures, some cells remain resident in the node and tailbud. Could these cells be resident axial stem cells? If so, do the node and tailbud represent an instructive stem cell niche that specifies and maintains these stem cells? Serial transplantation and single cell labelling studies support the existence of self-renewing stem cells and heterotopic transplantations suggest that the node can instruct such self-renewing behaviour. However, only single cell manipulations can reveal whether self-renewing behaviour occurs at the level of a cell population (asymmetric or symmetric cell divisions) or at the level of single cells (asymmetric divisions only). We combine data on resident cells in the node and tailbud and review it in the context of axial development in chick and mouse, summarising our current understanding of axial stem cells and their niche and highlighting future directions of interest.
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Affiliation(s)
- Tatiana Solovieva
- Department of Cell and Developmental Biology, University College London, UK
| | - Valerie Wilson
- Centre for Regenerative Medicine, The University of Edinburgh, UK
| | - Claudio D Stern
- Department of Cell and Developmental Biology, University College London, UK.
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9
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Sainz de la Maza D, Hof-Michel S, Phillimore L, Bökel C, Amoyel M. Cell-cycle exit and stem cell differentiation are coupled through regulation of mitochondrial activity in the Drosophila testis. Cell Rep 2022; 39:110774. [PMID: 35545055 PMCID: PMC9350557 DOI: 10.1016/j.celrep.2022.110774] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2021] [Revised: 02/21/2022] [Accepted: 04/12/2022] [Indexed: 11/27/2022] Open
Abstract
Whereas stem and progenitor cells proliferate to maintain tissue homeostasis, fully differentiated cells exit the cell cycle. How cell identity and cell-cycle state are coordinated during differentiation is still poorly understood. The Drosophila testis niche supports germline stem cells and somatic cyst stem cells (CySCs). CySCs give rise to post-mitotic cyst cells, providing a tractable model to study the links between stem cell identity and proliferation. We show that, while cell-cycle progression is required for CySC self-renewal, the E2f1/Dp transcription factor is dispensable for self-renewal but instead must be silenced by the Drosophila retinoblastoma homolog, Rbf, to permit differentiation. Continued E2f1/Dp activity inhibits the expression of genes important for mitochondrial activity. Furthermore, promoting mitochondrial biogenesis rescues the differentiation of CySCs with ectopic E2f1/Dp activity but not their cell-cycle exit. In sum, E2f1/Dp coordinates cell-cycle progression with stem cell identity by regulating the metabolic state of CySCs. CycE is critical for CySC self-renewal E2f/Dp does not act in self-renewal but must be silenced for differentiation E2f/Dp inhibits increases in oxidative metabolism involved in normal differentiation Increased mitochondrial biogenesis rescues differentiation of E2f/Dp-active cells
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Affiliation(s)
- Diego Sainz de la Maza
- Department of Cell and Developmental Biology, University College London, Gower Street, London WC1E 6BT, UK
| | - Silvana Hof-Michel
- Department of Developmental Genetics, Philipps University Marburg, Karl-von-Frisch-Str. 8, 35043 Marburg, Germany
| | - Lee Phillimore
- Department of Cell and Developmental Biology, University College London, Gower Street, London WC1E 6BT, UK
| | - Christian Bökel
- Department of Developmental Genetics, Philipps University Marburg, Karl-von-Frisch-Str. 8, 35043 Marburg, Germany.
| | - Marc Amoyel
- Department of Cell and Developmental Biology, University College London, Gower Street, London WC1E 6BT, UK.
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10
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Ranjan R, Snedeker J, Wooten M, Chu C, Bracero S, Mouton T, Chen X. Differential condensation of sister chromatids acts with Cdc6 to ensure asynchronous S-phase entry in Drosophila male germline stem cell lineage. Dev Cell 2022; 57:1102-1118.e7. [PMID: 35483360 PMCID: PMC9134767 DOI: 10.1016/j.devcel.2022.04.007] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2021] [Revised: 01/16/2022] [Accepted: 04/05/2022] [Indexed: 01/06/2023]
Abstract
During Drosophila melanogaster male germline stem cell (GSC) asymmetric division, preexisting old versus newly synthesized histones H3 and H4 are asymmetrically inherited. However, the biological outcomes of this phenomenon have remained unclear. Here, we tracked old and new histones throughout the GSC cell cycle through the use of high spatial and temporal resolution microscopy. We found unique features that differ between old and new histone-enriched sister chromatids, including differences in nucleosome density, chromosomal condensation, and H3 Ser10 phosphorylation. These distinct chromosomal features lead to their differential association with Cdc6, a pre-replication complex component, and subsequent asynchronous DNA replication initiation in the resulting daughter cells. Disruption of asymmetric histone inheritance abolishes differential Cdc6 association and asynchronous S-phase entry, demonstrating that histone asymmetry acts upstream of these critical cell-cycle progression events. Furthermore, disruption of these GSC-specific chromatin features leads to GSC defects, indicating a connection between histone inheritance, cell-cycle progression, and cell fate determination.
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Affiliation(s)
- Rajesh Ranjan
- Howard Hughes Medical Institute, Department of Biology, The Johns Hopkins University, Baltimore, MD 21218, USA; Department of Biology, The Johns Hopkins University, Baltimore, MD 21218, USA.
| | - Jonathan Snedeker
- Department of Biology, The Johns Hopkins University, Baltimore, MD 21218, USA
| | - Matthew Wooten
- Department of Biology, The Johns Hopkins University, Baltimore, MD 21218, USA
| | - Carolina Chu
- Department of Biology, The Johns Hopkins University, Baltimore, MD 21218, USA
| | - Sabrina Bracero
- Department of Biology, The Johns Hopkins University, Baltimore, MD 21218, USA
| | - Taylar Mouton
- Department of Biology, The Johns Hopkins University, Baltimore, MD 21218, USA
| | - Xin Chen
- Howard Hughes Medical Institute, Department of Biology, The Johns Hopkins University, Baltimore, MD 21218, USA; Department of Biology, The Johns Hopkins University, Baltimore, MD 21218, USA.
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11
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Bhaskar PK, Southard S, Baxter K, Van Doren M. Germline sex determination regulates sex-specific signaling between germline stem cells and their niche. Cell Rep 2022; 39:110620. [PMID: 35385723 PMCID: PMC10462394 DOI: 10.1016/j.celrep.2022.110620] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2021] [Revised: 12/20/2021] [Accepted: 03/15/2022] [Indexed: 11/03/2022] Open
Abstract
Establishing germ cell sexual identity is critical for development of male and female germline stem cells (GSCs) and production of sperm or eggs. Germ cells depend on signals from the somatic gonad to determine sex, but in organisms such as flies, mice, and humans, the sex chromosome genotype of the germ cells is also important for germline sexual development. How somatic signals and germ-cell-intrinsic cues combine to regulate germline sex determination is thus a key question. We find that JAK/STAT signaling in the GSC niche promotes male identity in germ cells, in part by activating the chromatin reader Phf7. Further, we find that JAK/STAT signaling is blocked in XX (female) germ cells through the action of the sex determination gene Sex lethal to preserve female identity. Thus, an important function of germline sexual identity is to control how GSCs respond to signals in their niche environment.
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Affiliation(s)
- Pradeep Kumar Bhaskar
- Department of Biology, Johns Hopkins University, 3400 N. Charles Street, Baltimore, MD 21218, USA
| | - Sheryl Southard
- Department of Biology, Johns Hopkins University, 3400 N. Charles Street, Baltimore, MD 21218, USA
| | - Kelly Baxter
- Department of Biology, Johns Hopkins University, 3400 N. Charles Street, Baltimore, MD 21218, USA
| | - Mark Van Doren
- Department of Biology, Johns Hopkins University, 3400 N. Charles Street, Baltimore, MD 21218, USA.
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12
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Herrera SC, Bach EA. The Emerging Roles of JNK Signaling in Drosophila Stem Cell Homeostasis. Int J Mol Sci 2021; 22:ijms22115519. [PMID: 34073743 PMCID: PMC8197226 DOI: 10.3390/ijms22115519] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2021] [Revised: 05/20/2021] [Accepted: 05/21/2021] [Indexed: 12/11/2022] Open
Abstract
The Jun N-terminal kinase (JNK) pathway is an evolutionary conserved kinase cascade best known for its roles during stress-induced apoptosis and tumor progression. Recent findings, however, have identified new roles for this pleiotropic pathway in stem cells during regenerative responses and in cellular plasticity. Here, we provide an overview of recent findings about the new roles of JNK signaling in stem cell biology using two well-established Drosophila models: the testis and the intestine. We highlight the pathway’s roles in processes such as proliferation, death, self-renewal and reprogramming, and discuss the known parallels between flies and mammals.
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Affiliation(s)
- Salvador C. Herrera
- Centro Andaluz de Biología del Desarrollo, CSIC/Universidad Pablo de Olavide/JA, Carretera de Utrera km 1, 41018 Sevilla, Spain
- Correspondence: (S.C.H.); (E.A.B.)
| | - Erika A. Bach
- Department of Biochemistry and Molecular Pharmacology, New York University Grossman School of Medicine, New York, NY 10016, USA
- Helen L. and Martin S. Kimmel Center for Stem Cell Biology, New York University Grossman School of Medicine, New York, NY 10016, USA
- Correspondence: (S.C.H.); (E.A.B.)
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13
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Fang Y, Zong Q, He Z, Liu C, Wang YF. Knockdown of RpL36 in testes impairs spermatogenesis in Drosophila melanogaster. JOURNAL OF EXPERIMENTAL ZOOLOGY PART B-MOLECULAR AND DEVELOPMENTAL EVOLUTION 2021; 336:417-430. [PMID: 33734578 DOI: 10.1002/jez.b.23040] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/16/2019] [Revised: 02/06/2021] [Accepted: 02/27/2021] [Indexed: 01/03/2023]
Abstract
Many ribosomal proteins (RPs) not only play essential roles in ribosome biogenesis, but also have "extraribosomal" functions in various cellular processes. RpL36 encodes ribosomal protein L36, a component of the 60S subunit of ribosomes in Drosophila melanogaster. We report here that RpL36 is required for spermatogenesis in D. melanogaster. After showing the evolutionary conservation of RpL36 sequences in animals, we revealed that the RpL36 expression level in fly testes was significantly higher than in ovaries. Knockdown RpL36 in fly testes resulted in a significantly decreased egg hatch rate when these males mated with wild-type females. Furthermore, 76.67% of the RpL36 knockdown fly testes were much smaller in comparison to controls. Immunofluorescence staining exhibited that in the RpL36 knockdown testis hub cell cluster was enlarged, while the number of germ cells, including germ stem cells, was reduced. Knockdown of RpL36 in fly testis caused much fewer or no mature sperms in seminal vesicles. The terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) signal was stronger in RpL36 knockdown fly testes than in the control testes, but the TUNEL-positive cells could not be stained by Vasa antibody, indicating that apoptotic cells are not germ cells. The percentage of pH3-positive cells among the Vasa-positive cells was significantly reduced. The expression of genes involved in cell death, cell cycle progression, and JAK/STAT signaling pathway was significantly changed by RpL36 knockdown in fly testes. These results suggest that RpL36 plays an important role in spermatogenesis, likely through JAK/STAT pathway, thus resulting in defects in cell-cycle progression and cell death in D. melanogaster testes.
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Affiliation(s)
- Yang Fang
- School of Life Sciences, Hubei Key Laboratory of Genetic Regulation and Integrative Biology, Central China Normal University, Wuhan, China
| | - Qiong Zong
- School of Life Sciences, Hubei Key Laboratory of Genetic Regulation and Integrative Biology, Central China Normal University, Wuhan, China
| | - Zhen He
- School of Life Sciences, Hubei Key Laboratory of Genetic Regulation and Integrative Biology, Central China Normal University, Wuhan, China
| | - Chen Liu
- Institute of Biology and Medicine, Wuhan University of Science and Technology, Wuhan, China
| | - Yu-Feng Wang
- School of Life Sciences, Hubei Key Laboratory of Genetic Regulation and Integrative Biology, Central China Normal University, Wuhan, China
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14
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Bazylev SS, Adashev VE, Shatskikh AS, Olenina LV, Kotov AA. Somatic Cyst Cells as a Microenvironment for the Maintenance and Differentiation of Germline Cells in Drosophila Spermatogenesis. Russ J Dev Biol 2021. [DOI: 10.1134/s1062360421010021] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
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15
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Vidaurre V, Chen X. Epigenetic regulation of drosophila germline stem cell maintenance and differentiation. Dev Biol 2021; 473:105-118. [PMID: 33610541 DOI: 10.1016/j.ydbio.2021.02.003] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2020] [Revised: 01/26/2021] [Accepted: 02/06/2021] [Indexed: 12/13/2022]
Abstract
Gametogenesis is one of the most extreme cellular differentiation processes that takes place in Drosophila male and female germlines. This process begins at the germline stem cell, which undergoes asymmetric cell division (ACD) to produce a self-renewed daughter that preserves its stemness and a differentiating daughter cell that undergoes epigenetic and genomic changes to eventually produce haploid gametes. Research in molecular genetics and cellular biology are beginning to take advantage of the continually advancing genomic tools to understand: (1) how germ cells are able to maintain their identity throughout the adult reproductive lifetime, and (2) undergo differentiation in a balanced manner. In this review, we focus on the epigenetic mechanisms that address these two questions through their regulation of germline-soma communication to ensure germline stem cell identity and activity.
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Affiliation(s)
- Velinda Vidaurre
- Department of Biology, The Johns Hopkins University, 3400 North Charles Street, Baltimore, Baltimore, MD, 21218, USA
| | - Xin Chen
- Department of Biology, The Johns Hopkins University, 3400 North Charles Street, Baltimore, Baltimore, MD, 21218, USA.
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16
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Greenspan LJ, Matunis EL. Retinoblastoma Intrinsically Regulates Niche Cell Quiescence, Identity, and Niche Number in the Adult Drosophila Testis. Cell Rep 2019; 24:3466-3476.e8. [PMID: 30257208 PMCID: PMC6226258 DOI: 10.1016/j.celrep.2018.08.083] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2018] [Revised: 05/29/2018] [Accepted: 08/27/2018] [Indexed: 12/20/2022] Open
Abstract
Homeostasis in adult tissues depends on the precise regulation of stem cells and their surrounding microenvironments, or niches. Here, we show that the cell cycle inhibitor and tumor suppressor Retinoblastoma (RB) is a critical regulator of niche cells in the Drosophila testis. The testis contains a single niche, composed of somatic hub cells, that signals to adjacent germline and somatic stem cells. Hub cells are normally quiescent, but knockdown of the RB homolog Rbf in these cells causes them to proliferate and convert to somatic stem cells. Over time, mutant hub cell clusters enlarge and split apart, forming ectopic hubs surrounded by active stem cells. Furthermore, we show that Rbf’s ability to restrict niche number depends on the transcription factors E2F and Escargot and the adhesion molecule E-cadherin. Together this work reveals how precise modulation of niche cells, not only the stem cells they support, can drive regeneration and disease. Greenspan and Matunis find that the tumor suppressor Retinoblastoma is required in niche cells to maintain quiescence, cell fate, and niche number. Loss of Retinoblastoma causes niche cell divisions, conversion to somatic stem cells, and ectopic niche formation through niche fission, suggesting that mutations in niche cells may drive disease.
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Affiliation(s)
- Leah J Greenspan
- Department of Cell Biology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Erika L Matunis
- Department of Cell Biology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.
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17
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Asymmetric Centromeres Differentially Coordinate with Mitotic Machinery to Ensure Biased Sister Chromatid Segregation in Germline Stem Cells. Cell Stem Cell 2019; 25:666-681.e5. [PMID: 31564548 DOI: 10.1016/j.stem.2019.08.014] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2019] [Revised: 06/25/2019] [Accepted: 08/19/2019] [Indexed: 12/29/2022]
Abstract
Many stem cells utilize asymmetric cell division (ACD) to produce a self-renewed stem cell and a differentiating daughter cell. How non-genic information could be inherited differentially to establish distinct cell fates is not well understood. Here, we report a series of spatiotemporally regulated asymmetric components, which ensure biased sister chromatid attachment and segregation during ACD of Drosophila male germline stem cells (GSCs). First, sister centromeres are differentially enriched with proteins involved in centromere specification and kinetochore function. Second, temporally asymmetric microtubule activities and polarized nuclear envelope breakdown allow for the preferential recognition and attachment of microtubules to asymmetric sister kinetochores and sister centromeres. Abolishment of either the asymmetric sister centromeres or the asymmetric microtubule activities results in randomized sister chromatid segregation. Together, these results provide the cellular basis for partitioning epigenetically distinct sister chromatids during stem cell ACDs, which opens new directions to study these mechanisms in other biological contexts.
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18
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Flint Brodsly N, Bitman-Lotan E, Boico O, Shafat A, Monastirioti M, Gessler M, Delidakis C, Rincon-Arano H, Orian A. The transcription factor Hey and nuclear lamins specify and maintain cell identity. eLife 2019; 8:44745. [PMID: 31310235 PMCID: PMC6634966 DOI: 10.7554/elife.44745] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2018] [Accepted: 07/03/2019] [Indexed: 12/12/2022] Open
Abstract
The inability of differentiated cells to maintain their identity is a hallmark of age-related diseases. We found that the transcription factor Hey supervises the identity of differentiated enterocytes (ECs) in the adult Drosophila midgut. Lineage tracing established that Hey-deficient ECs are unable to maintain their unique nuclear organization and identity. To supervise cell identity, Hey determines the expression of nuclear lamins, switching from a stem-cell lamin configuration to a differentiated lamin configuration. Moreover, continued Hey expression is required to conserve large-scale nuclear organization. During aging, Hey levels decline, and EC identity and gut homeostasis are impaired, including pathological reprograming and compromised gut integrity. These phenotypes are highly similar to those observed upon acute targeting of Hey or perturbation of lamin expression in ECs in young adults. Indeed, aging phenotypes were suppressed by continued expression of Hey in ECs, suggesting that a Hey-lamin network safeguards nuclear organization and differentiated cell identity.
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Affiliation(s)
- Naama Flint Brodsly
- Rappaport Research Institute and Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel
| | - Eliya Bitman-Lotan
- Rappaport Research Institute and Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel
| | - Olga Boico
- Rappaport Research Institute and Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel
| | - Adi Shafat
- Rappaport Research Institute and Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel
| | - Maria Monastirioti
- Institute of Molecular Biology and Biotechnology (IMBB), Foundation for Research and Technology - Hellas (FORTH), Heraklion, Greece
| | - Manfred Gessler
- Biocenter of Developmental Biochemistry, University of Würzburg, Würzburg, Germany
| | - Christos Delidakis
- Institute of Molecular Biology and Biotechnology (IMBB), Foundation for Research and Technology - Hellas (FORTH), Heraklion, Greece
| | - Hector Rincon-Arano
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, United States
| | - Amir Orian
- Rappaport Research Institute and Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel
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19
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Reproduction disrupts stem cell homeostasis in testes of aged male Drosophila via an induced microenvironment. PLoS Genet 2019; 15:e1008062. [PMID: 31295251 PMCID: PMC6622487 DOI: 10.1371/journal.pgen.1008062] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2018] [Accepted: 03/02/2019] [Indexed: 12/13/2022] Open
Abstract
Stem cells rely on instructive cues from their environment. Alterations in microenvironments might contribute to tissue dysfunction and disease pathogenesis. Germline stem cells (GSCs) and cyst stem cells (CySC) in Drosophila testes are normally maintained in the apical area by the testicular hub. In this study, we found that reproduction leads to accumulation of early differentiating daughters of CySCs and GSCs in the testes of aged male flies, due to hyperactivation of Jun-N-terminal kinase (JNK) signaling to maintain self-renewal gene expression in the differentiating cyst cells. JNK activity is normally required to maintain CySCs in the apical niche. A muscle sheath surrounds the Drosophila testis to maintain its long coiled structure. Importantly, reproduction triggers accumulation of the tumor necrosis factor (TNF) Eiger in the testis muscle to activate JNK signaling via the TNF receptor Grindelwald in the cyst cells. Reducing Eiger activity in the testis muscle sheath suppressed reproduction-induced differentiation defects, but had little effect on testis homeostasis of unmated males. Our results reveal that reproduction in males provokes a dramatic shift in the testicular microenvironment, which impairs tissue homeostasis and spermatogenesis in the testes. Proper differentiation of stem cell progeny is necessary for preservation of tissue homeostasis. In Drosophila testes, somatic cyst cells derived from the cyst stem cells (CySCs) control the differentiation of the neighboring germ cells. Disruption of CySC daughter cyst cell differentiation leads to failure in sperm production. Interestingly, we found that reproduction triggers hyperactivation of Jun-N-terminal kinase (JNK) signaling to sustain CySC self-renewal gene expression in differentiating cyst cells, leading to accumulation of immature cyst cell and germ cells at the expense of mature cells in the testes of aged males. Endogenous JNK signaling is also required for CySC maintenance. Moreover, we found that the JNK signaling is hyperactivated via reproduction-induced accumulation of tumor necrosis factor (TNF) in testicular smooth muscle that surrounds the testis to support its long coiled structure. The reproduction-induced phenotypes were only observed in the testes of aged and mated males, but not in testes form young mated males or aged unmated males, indicating that it is a combined effect of reproduction and aging. Our results reveal that reproduction impedes sperm production in aged males, and identify testicular muscle as an inducible signaling center for spermatogenesis in Drosophila.
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20
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Camara N, Whitworth C, Dove A, Van Doren M. Doublesex controls specification and maintenance of the gonad stem cell niches in Drosophila. Development 2019; 146:dev.170001. [PMID: 31043421 DOI: 10.1242/dev.170001] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2018] [Accepted: 04/23/2019] [Indexed: 11/20/2022]
Abstract
Sex-specific development of the gonads is a key aspect of sexual dimorphism that is regulated by Doublesex/Mab3-related transcription factors (DMRTs) in diverse animal species. We find that in mutants for Drosophila dsx, important components of the male and female gonad stem cell niches (hubs and terminal filaments/cap cells, respectively) still form. Initially, gonads in all dsx mutants (both XX and XY) initiate the male program of development, but later half of these gonads switch to form female stem cell niche structures. One individual can have both male-type and female-type gonad niches; however, male and female niches are usually not observed in the same gonad, indicating that cells make a 'group decision' about which program to follow. We conclude that dsx does not act in an instructive manner to regulate male versus female niche formation, as these structures form in the absence of dsx function. Instead, dsx acts to 'tip the balance' between the male or female programs, which are then executed independently of dsx We show that bric a brac acts downstream of dsx to control the male versus female niche decision. These results indicate that, in both flies and mammals, the sexual fate of the somatic gonad is remarkably plastic and is controlled by a combination of autonomous and non-autonomous cues.
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Affiliation(s)
- Nicole Camara
- Department of Biology, Johns Hopkins University, 3400 N. Charles Street, Baltimore, MD 21218, USA
| | - Cale Whitworth
- Department of Biology, Johns Hopkins University, 3400 N. Charles Street, Baltimore, MD 21218, USA
| | - Abigail Dove
- Department of Biology, Johns Hopkins University, 3400 N. Charles Street, Baltimore, MD 21218, USA
| | - Mark Van Doren
- Department of Biology, Johns Hopkins University, 3400 N. Charles Street, Baltimore, MD 21218, USA
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21
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Papagiannouli F, Berry CW, Fuller MT. The Dlg Module and Clathrin-Mediated Endocytosis Regulate EGFR Signaling and Cyst Cell-Germline Coordination in the Drosophila Testis. Stem Cell Reports 2019; 12:1024-1040. [PMID: 31006632 PMCID: PMC6523063 DOI: 10.1016/j.stemcr.2019.03.008] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2018] [Revised: 03/21/2019] [Accepted: 03/22/2019] [Indexed: 11/25/2022] Open
Abstract
Tissue homeostasis and repair relies on proper communication of stem cells and their differentiating daughters with the local tissue microenvironment. In the Drosophila male germline adult stem cell lineage, germ cells proliferate and progressively differentiate enclosed in supportive somatic cyst cells, forming a small organoid, the functional unit of differentiation. Here we show that cell polarity and vesicle trafficking influence signal transduction in cyst cells, with profound effects on the germ cells they enclose. Our data suggest that the cortical components Dlg, Scrib, Lgl and the clathrin-mediated endocytic (CME) machinery downregulate epidermal growth factor receptor (EGFR) signaling. Knockdown of dlg, scrib, lgl, or CME components in cyst cells resulted in germ cell death, similar to increased signal transduction via the EGFR, while lowering EGFR or downstream signaling components rescued the defects. This work provides insights into how cell polarity and endocytosis cooperate to regulate signal transduction and sculpt developing tissues. Dlg, Scrib, Lgl, and clathrin-mediated endocytosis (CME) attenuate EGFR signaling Knockdown of Dlg module or CME results in cell non-autonomous germ cell death Dlg module and CME control MAPK activation and the levels of the PIP2 phospholipid PIP2 and its synthesizing kinase Sktl/dPIP5K mediate MAPK activation
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Affiliation(s)
- Fani Papagiannouli
- Department of Developmental Biology, Beckman Center, Stanford University School of Medicine, Stanford, CA 94305-5329, USA; Institute for Genetics, University of Cologne, 50674 Cologne, Germany.
| | - Cameron Wynn Berry
- Department of Developmental Biology, Beckman Center, Stanford University School of Medicine, Stanford, CA 94305-5329, USA
| | - Margaret T Fuller
- Department of Developmental Biology, Beckman Center, Stanford University School of Medicine, Stanford, CA 94305-5329, USA
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22
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Lu Y, Yao Y, Li Z. Ectopic Dpp signaling promotes stem cell competition through EGFR signaling in the Drosophila testis. Sci Rep 2019; 9:6118. [PMID: 30992503 PMCID: PMC6467874 DOI: 10.1038/s41598-019-42630-y] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2018] [Accepted: 04/02/2019] [Indexed: 12/28/2022] Open
Abstract
Stem cell competition could select the fittest stem cells and potentially control tumorigenesis. However, little is known about the underlying molecular mechanisms. Here, we find that ectopic Decapentaplegic (Dpp) signal activation by expressing a constitutively active form of Thickveins (TkvCA) in cyst stem cells (CySCs) leads to competition between CySCs and germline stem cells (GSCs) for niche occupancy and GSC loss. GSCs are displaced from the niche and undergo differentiation. Interestingly, we find that induction of TkvCA results in elevated expression of vein, which further activates Epidermal Growth Factor Receptor (EGFR) signaling in CySCs to promote their proliferation and compete GSCs out of the niche. Our findings elucidate the important role of Dpp signaling in regulating stem cell competition and tumorigenesis, which could be shed light on tumorigenesis and cancer treatment in mammals.
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Affiliation(s)
- Yanfen Lu
- College of Plant Science and Technology, Beijing University of Agriculture, No. 7 Beinong Road, Changping District, Beijing, 102206, China
| | - Yuncong Yao
- College of Plant Science and Technology, Beijing University of Agriculture, No. 7 Beinong Road, Changping District, Beijing, 102206, China.
| | - Zhouhua Li
- College of Life Sciences, Capital Normal University, Beijing, 100048, China.
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23
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Brantley SE, Fuller MT. Somatic support cells regulate germ cell survival through the Baz/aPKC/Par6 complex. Development 2019; 146:dev.169342. [PMID: 30918053 PMCID: PMC6503986 DOI: 10.1242/dev.169342] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2018] [Accepted: 03/21/2019] [Indexed: 12/16/2022]
Abstract
Local signals and structural support from the surrounding cellular microenvironment play key roles in directing development in both embryonic organs and adult tissues. In Drosophila, male germ cells are intimately associated and co-differentiate with supporting somatic cells. Here, we show that the function of the Baz/aPKC/Par6 apical polarity complex in somatic cyst cells is required stage specifically for survival of the germ cells they enclose. Although spermatogonia enclosed by cyst cells in which the function of the Par complex had been knocked down survived and proliferated, newly formed spermatocytes enclosed by cyst cells lacking Par complex proteins died soon after onset of meiotic prophase. Loss of Par complex function resulted in stage-specific overactivation of the Jun-kinase (JNK) pathway in cyst cells. Knocking down expression of JNK pathway components or the GTPase Rab35 in cyst cells lacking Par complex function rescued the survival of neighboring spermatocytes, suggesting that action of the apical polarity complex ensures germ cell survival by preventing JNK pathway activation, and that the mechanism by which cyst cells lacking Par complex function kill neighboring spermatocytes requires intracellular trafficking in somatic cyst cells. Summary: The Par polarity complex suppresses JNK pathway activity in Drosophila somatic support cells to allow stage-specific germ cell survival.
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Affiliation(s)
- Susanna E Brantley
- Department of Developmental Biology, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Margaret T Fuller
- Department of Developmental Biology, Stanford University School of Medicine, Stanford, CA 94305, USA
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24
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Francis D, Chanana B, Fernandez B, Gordon B, Mak T, Palacios IM. YAP/Yorkie in the germline modulates the age-related decline of germline stem cells and niche cells. PLoS One 2019; 14:e0213327. [PMID: 30943201 PMCID: PMC6447158 DOI: 10.1371/journal.pone.0213327] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2019] [Accepted: 02/18/2019] [Indexed: 11/19/2022] Open
Abstract
The properties and behaviour of stem cells rely heavily on signaling from the local microenvironment. At the apical end of Drosophila testis, self-renewal and differentiation of germline stem cells (GSCs) are tightly controlled by distinct somatic cells that comprise a specialised stem cell niche known as the hub. The hub maintains GSC homeostasis through adhesion and cell signaling. The Salvador/Warts/Hippo (SWH) pathway, which suppresses the transcriptional co-activator YAP/Yki via a kinase cascade, is a known regulator of stem cell proliferation and differentiation. Here, we show that increasing YAP/Yki expression in the germline, as well as reducing Warts levels, blocks the decrease of GSC numbers observed in aging flies, with only a small increase on their proliferation. An increased expression of YAP/Yki in the germline or a reduction in Warts levels also stymies an age-related reduction in hub cell number, suggesting a bilateral relationship between GSCs and the hub. Conversely, RNAi-based knockdown of YAP/Yki in the germline leads to a significant drop in hub cell number, further suggesting the existence of such a SC-to-niche relationship. All together, our data implicate the SWH pathway in Drosophila GSC maintenance and raise questions about its role in stem cell homeostasis in aging organisms.
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Affiliation(s)
| | | | - Beatriz Fernandez
- School of Biological and Chemical Sciences, Queen Mary University of London, Mile End Road, London, United Kingdom
| | | | - Tiffany Mak
- University of Cambridge, Cambridge, United Kingdom
| | - Isabel M. Palacios
- University of Cambridge, Cambridge, United Kingdom
- School of Biological and Chemical Sciences, Queen Mary University of London, Mile End Road, London, United Kingdom
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25
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Spermatogenesis and lobular cyst type of testes organization in marine gastropod Littorina saxatilis (Olivi 1792). Cell Tissue Res 2019; 376:457-470. [PMID: 30778731 DOI: 10.1007/s00441-019-03004-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2018] [Accepted: 02/07/2019] [Indexed: 10/27/2022]
Abstract
Although individual stages of spermatogenesis in Littorina saxatilis are well studied at the electron microscopic level, the gonad structure and the spatial localization of gametes at different stages of maturation remain unclear. Using differential-interference contrast (DIC) for observations of fresh tissue we show that the mature testis consists of numerous ovoid lobules forming larger lobes. The lobules of intact mature testes of L. saxatilis are filled with randomly arranged multicellular cysts containing gametes at different stages of maturation. Gametes within a cyst are highly synchronized in respect of the differentiation degree. At the same time, no spatial gradient in the arrangement of cysts according to the maturation degree of gametes in them was observed in any of the studied lobules. The male gonads contain cysts with early spermatids, mid, late spermatids, and spermatozoa. Using silver-staining, DAPI, and chromomycin A3 (CMA3) staining, we identify 20 main types of nucleus organization in differentiating sperm. Premature and mature male gonads contain cysts with a mosaic arrangement as well as rare solitary cyst cells, goniablast cysts, or separate spermatogonia in between them. Our data indicate that the testis structure in L. saxatilis cannot be attributed to the tubular type, as previously thought. It corresponds to the lobular cyst type but individual lobules contain cysts with gametes at the same stage of development. It is similar to the testis structure of several fishes, amphibians, and Drosophila melanogaster. This type of the gonad organization has never been described in gastropods before.
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26
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Herrera SC, Bach EA. JAK/STAT signaling in stem cells and regeneration: from Drosophila to vertebrates. Development 2019; 146:dev167643. [PMID: 30696713 PMCID: PMC6361132 DOI: 10.1242/dev.167643] [Citation(s) in RCA: 102] [Impact Index Per Article: 20.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2018] [Accepted: 12/03/2018] [Indexed: 12/19/2022]
Abstract
The JAK/STAT pathway is a conserved metazoan signaling system that transduces cues from extracellular cytokines into transcriptional changes in the nucleus. JAK/STAT signaling is best known for its roles in immunity. However, recent work has demonstrated that it also regulates critical homeostatic processes in germline and somatic stem cells, as well as regenerative processes in several tissues, including the gonad, intestine and appendages. Here, we provide an overview of JAK/STAT signaling in stem cells and regeneration, focusing on Drosophila and highlighting JAK/STAT pathway functions in proliferation, survival and cell competition that are conserved between Drosophila and vertebrates.
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Affiliation(s)
- Salvador C Herrera
- Department of Biochemistry and Molecular Pharmacology, New York University School of Medicine, New York, NY 10016, USA
| | - Erika A Bach
- Department of Biochemistry and Molecular Pharmacology, New York University School of Medicine, New York, NY 10016, USA
- Helen L. and Martin S. Kimmel Center for Stem Cell Biology, New York University School of Medicine, New York, NY 10016, USA
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27
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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: 10] [Impact Index Per Article: 2.0] [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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28
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Zheng Y, Bi J, Hou MY, Shen W, Zhang W, Ai H, Yu XQ, Wang YF. Ocnus is essential for male germ cell development in Drosophila melanogaster. INSECT MOLECULAR BIOLOGY 2018; 27:545-555. [PMID: 29732657 DOI: 10.1111/imb.12393] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
The ocnus (ocn) gene encodes a protein abundant in the testes, implying its role in testis development. When Drosophila melanogaster is infected with the endosymbiont wMel Wolbachia, which affects the spermatogenesis of its hosts, ocn is downregulated in the third-instar larval testes, suggesting a role of ocn in spermatogenesis. In this study, we knocked down ocn in the testes and found that the hatch rates of embryos derived from ocn-knockdown males were significantly decreased, and 84.38% of the testes were much smaller in comparison to controls. Analysis of the smaller testes showed no germ cells but they had an extended hub. Using RNA-sequencing (RNA-Seq), we identified 69 genes with at least a twofold change (q-value < 5%) in their expression after ocn knockdown; of these, eight testes-specific and three reproduction-related genes were verified to be significantly downregulated using quantitative reverse transcription-PCR. Three genes (orientation disruptor, p24-2 and CG13541) were also significantly downregulated in the presence of Wolbachia. Furthermore, 98 genes were not expressed when ocn was knocked down in testes. These results suggest that ocn plays a crucial role in male germ cell development in Drosophila, possibly by regulating the expression of multiple spermatogenesis-related genes. Our data provide important information to help understand the molecular regulatory mechanisms underlying spermatogenesis.
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Affiliation(s)
- Y Zheng
- Hubei Key Laboratory of Genetic Regulation and Integrative Biology, School of Life Sciences, Central China Normal University, Wuhan, China
| | - J Bi
- Hubei Key Laboratory of Genetic Regulation and Integrative Biology, School of Life Sciences, Central China Normal University, Wuhan, China
| | - M-Y Hou
- Hubei Key Laboratory of Genetic Regulation and Integrative Biology, School of Life Sciences, Central China Normal University, Wuhan, China
| | - W Shen
- Hubei Key Laboratory of Genetic Regulation and Integrative Biology, School of Life Sciences, Central China Normal University, Wuhan, China
| | - W Zhang
- Hubei Key Laboratory of Genetic Regulation and Integrative Biology, School of Life Sciences, Central China Normal University, Wuhan, China
| | - H Ai
- Hubei Key Laboratory of Genetic Regulation and Integrative Biology, School of Life Sciences, Central China Normal University, Wuhan, China
| | - X-Q Yu
- Hubei Key Laboratory of Genetic Regulation and Integrative Biology, School of Life Sciences, Central China Normal University, Wuhan, China
- School of Biological Sciences, University of Missouri-Kansas City, Kansas City, MO, USA
| | - Y-F Wang
- Hubei Key Laboratory of Genetic Regulation and Integrative Biology, School of Life Sciences, Central China Normal University, Wuhan, China
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29
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Tamirisa S, Papagiannouli F, Rempel E, Ermakova O, Trost N, Zhou J, Mundorf J, Brunel S, Ruhland N, Boutros M, Lohmann JU, Lohmann I. Decoding the Regulatory Logic of the Drosophila Male Stem Cell System. Cell Rep 2018; 24:3072-3086. [DOI: 10.1016/j.celrep.2018.08.013] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2017] [Revised: 04/13/2018] [Accepted: 08/06/2018] [Indexed: 10/28/2022] Open
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30
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Xu R, Li J, Zhao H, Kong R, Wei M, Shi L, Bai G, Li Z. Self-restrained regulation of stem cell niche activity by niche components in the Drosophila testis. Dev Biol 2018; 439:42-51. [PMID: 29679558 DOI: 10.1016/j.ydbio.2018.04.011] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2018] [Revised: 04/15/2018] [Accepted: 04/15/2018] [Indexed: 12/12/2022]
Abstract
Most, if not all, stem cells reside in a defined microenvironment, called the niche. Short-ranged niche signal must be tightly controlled to be active only inside the niche to maintain the proper balance of stem cell self-renewal verse differentiation. However, how niche components restrict localized niche signal activation remains largely unknown. Here, we find that Thickveins (Tkv, a type I receptor of the Dpp signaling pathway) in cyst stem cells (CySCs) of the testis niche prevents Dpp signaling activation outside of the niche. We show that Tkv functions as Dpp trap/sink to spatially restrain Dpp signaling inside the niche. This self-restrained regulation of niche activity by Tkv in CySCs is independent of the canonical Dpp signaling pathway. Our data demonstrate the critical roles of niche components (CySCs) in the self-restrained regulation of niche activity, which could be shed light on niche activity regulation in general.
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Affiliation(s)
- Ran Xu
- College of Life Sciences, Capital Normal University, Beijing 100048, China
| | - Jing Li
- College of Life Sciences, Capital Normal University, Beijing 100048, China
| | - Hang Zhao
- College of Life Sciences, Capital Normal University, Beijing 100048, China
| | - Ruiyan Kong
- College of Life Sciences, Capital Normal University, Beijing 100048, China
| | - Min Wei
- College of Life Sciences, Capital Normal University, Beijing 100048, China
| | - Lin Shi
- College of Life Sciences, Capital Normal University, Beijing 100048, China
| | - Guang Bai
- College of Life Sciences, Capital Normal University, Beijing 100048, China
| | - Zhouhua Li
- College of Life Sciences, Capital Normal University, Beijing 100048, China.
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Dominado N, La Marca JE, Siddall NA, Heaney J, Tran M, Cai Y, Yu F, Wang H, Somers WG, Quinn LM, Hime GR. Rbf Regulates Drosophila Spermatogenesis via Control of Somatic Stem and Progenitor Cell Fate in the Larval Testis. Stem Cell Reports 2017; 7:1152-1163. [PMID: 27974223 PMCID: PMC5161748 DOI: 10.1016/j.stemcr.2016.11.007] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2016] [Revised: 11/17/2016] [Accepted: 11/18/2016] [Indexed: 12/02/2022] Open
Abstract
The Drosophila testis has been fundamental to understanding how stem cells interact with their endogenous microenvironment, or niche, to control organ growth in vivo. Here, we report the identification of two independent alleles for the highly conserved tumor suppressor gene, Retinoblastoma-family protein (Rbf), in a screen for testis phenotypes in X chromosome third-instar lethal alleles. Rbf mutant alleles exhibit overproliferation of spermatogonial cells, which is phenocopied by the molecularly characterized Rbf11 null allele. We demonstrate that Rbf promotes cell-cycle exit and differentiation of the somatic and germline stem cells of the testes. Intriguingly, depletion of Rbf specifically in the germline does not disrupt stem cell differentiation, rather Rbf loss of function in the somatic lineage drives overproliferation and differentiation defects in both lineages. Together our observations suggest that Rbf in the somatic lineage controls germline stem cell renewal and differentiation non-autonomously via essential roles in the microenvironment of the germline lineage. Rbf null testes exhibit failure of germline stem cells to differentiate Rbf expression in somatic cells of L3 testes rescues the GSC differentiation defect Somatic Rbf RNAi disrupts cyst stem cell and germline stem cell differentiation Somatic depletion of E2f1 rescues Rbf germline proliferation and differentiation
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Affiliation(s)
- Nicole Dominado
- Centre for Stem Cell Systems, Department of Anatomy and Neuroscience, The University of Melbourne, Melbourne, VIC 3010, Australia; Department of Anatomy and Neuroscience, The University of Melbourne, Melbourne, VIC 3010, Australia
| | - John E La Marca
- Department of Genetics, La Trobe University, Melbourne, VIC 3086, Australia
| | - Nicole A Siddall
- Centre for Stem Cell Systems, Department of Anatomy and Neuroscience, The University of Melbourne, Melbourne, VIC 3010, Australia; Department of Anatomy and Neuroscience, The University of Melbourne, Melbourne, VIC 3010, Australia
| | - James Heaney
- Centre for Stem Cell Systems, Department of Anatomy and Neuroscience, The University of Melbourne, Melbourne, VIC 3010, Australia; Department of Anatomy and Neuroscience, The University of Melbourne, Melbourne, VIC 3010, Australia
| | - Mai Tran
- Department of Anatomy and Neuroscience, The University of Melbourne, Melbourne, VIC 3010, Australia
| | - Yu Cai
- Temasek Life Sciences Laboratory, National University of Singapore, Singapore 117543, Singapore; Department of Biological Sciences, National University of Singapore, Singapore 117543, Singapore
| | - Fengwei Yu
- Temasek Life Sciences Laboratory, National University of Singapore, Singapore 117543, Singapore
| | - Hongyan Wang
- Neuroscience & Behavioral Disorder Program, Duke-National University of Singapore, Singapore 169857, Singapore; Department of Physiology, National University of Singapore, Singapore 117597, Singapore
| | - W Gregory Somers
- Department of Genetics, La Trobe University, Melbourne, VIC 3086, Australia
| | - Leonie M Quinn
- Department of Anatomy and Neuroscience, The University of Melbourne, Melbourne, VIC 3010, Australia; The John Curtin School of Medical Research, The Australian National University, Acton, ACT 2601, Australia.
| | - Gary R Hime
- Centre for Stem Cell Systems, Department of Anatomy and Neuroscience, The University of Melbourne, Melbourne, VIC 3010, Australia; Department of Anatomy and Neuroscience, The University of Melbourne, Melbourne, VIC 3010, Australia.
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32
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Eun SH, Feng L, Cedeno-Rosario L, Gan Q, Wei G, Cui K, Zhao K, Chen X. Polycomb Group Gene E(z) Is Required for Spermatogonial Dedifferentiation in Drosophila Adult Testis. J Mol Biol 2017; 429:2030-2041. [PMID: 28434938 PMCID: PMC5516936 DOI: 10.1016/j.jmb.2017.04.012] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2017] [Revised: 03/30/2017] [Accepted: 04/17/2017] [Indexed: 12/12/2022]
Abstract
Dedifferentiation is an important process to replenish lost stem cells during aging or regeneration after injury to maintain tissue homeostasis. Here, we report that Enhancer of Zeste [E(z)], a component of the Polycomb repression complex 2 (PRC2), is required to maintain a stable pool of germline stem cells (GSCs) within the niche microenvironment. During aging, germ cells with reduced E(z) activity cannot meet that requirement, but the defect arises from neither increased GSC death nor premature differentiation. Instead, we found evidence that the decrease of GSCs upon the inactivation of E(z) in the germline could be attributed to defective dedifferentiation. During recovery from genetically manipulated GSC depletion, E(z) knockdown germ cells also fail to replenish lost GSCs. Taken together, our data suggest that E(z) acts intrinsically in germ cells to activate dedifferentiation and thus replenish lost GSCs during both aging and tissue regeneration.
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Affiliation(s)
- Suk Ho Eun
- Department of Biology, The Johns Hopkins University, Baltimore, MD 21218, USA
| | - Lijuan Feng
- Department of Biology, The Johns Hopkins University, Baltimore, MD 21218, USA
| | - Luis Cedeno-Rosario
- Department of Biology, The Johns Hopkins University, Baltimore, MD 21218, USA
| | - Qiang Gan
- Department of Biology, The Johns Hopkins University, Baltimore, MD 21218, USA
| | - Gang Wei
- Laboratory of Molecular Immunology, National Heart, Lung and Blood Institute, NIH, Bethesda, MD 20892, USA
| | - Kairong Cui
- Laboratory of Molecular Immunology, National Heart, Lung and Blood Institute, NIH, Bethesda, MD 20892, USA
| | - Keji Zhao
- Laboratory of Molecular Immunology, National Heart, Lung and Blood Institute, NIH, Bethesda, MD 20892, USA
| | - Xin Chen
- Department of Biology, The Johns Hopkins University, Baltimore, MD 21218, USA.
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33
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Silva D, Olsen KW, Bednarz MN, Droste A, Lenkeit CP, Chaharbakhshi E, Temple-Wood ER, Jemc JC. Regulation of Gonad Morphogenesis in Drosophila melanogaster by BTB Family Transcription Factors. PLoS One 2016; 11:e0167283. [PMID: 27898696 PMCID: PMC5127561 DOI: 10.1371/journal.pone.0167283] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2016] [Accepted: 11/07/2016] [Indexed: 02/06/2023] Open
Abstract
During embryogenesis, primordial germ cells (PGCs) and somatic gonadal precursor cells (SGPs) migrate and coalesce to form the early gonad. A failure of the PGCs and SGPs to form a gonad with the proper architecture not only affects germ cell development, but can also lead to infertility. Therefore, it is critical to identify the molecular mechanisms that function within both the PGCs and SGPs to promote gonad morphogenesis. We have characterized the phenotypes of two genes, longitudinals lacking (lola) and ribbon (rib), that are required for the coalescence and compaction of the embryonic gonad in Drosophila melanogaster. rib and lola are expressed in the SGPs of the developing gonad, and genetic interaction analysis suggests these proteins cooperate to regulate gonad development. Both genes encode proteins with DNA binding motifs and a conserved protein-protein interaction domain, known as the Broad complex, Tramtrack, Bric-à-brac (BTB) domain. Through molecular modeling and yeast-two hybrid studies, we demonstrate that Rib and Lola homo- and heterodimerize via their BTB domains. In addition, analysis of the colocalization of Rib and Lola with marks of transcriptional activation and repression on polytene chromosomes reveals that Rib and Lola colocalize with both repressive and activating marks and with each other. While previous studies have identified Rib and Lola targets in other tissues, we find that Rib and Lola are likely to function via different downstream targets in the gonad. These results suggest that Rib and Lola act as dual-function transcription factors to cooperatively regulate embryonic gonad morphogenesis.
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Affiliation(s)
- Diane Silva
- Department of Biology, Loyola University Chicago, Chicago, IL, United States of America
| | - Kenneth W. Olsen
- Department of Chemistry and Biochemistry, Loyola University Chicago, Chicago, IL, United States of America
| | - Magdalena N. Bednarz
- Department of Biology, Loyola University Chicago, Chicago, IL, United States of America
| | - Andrew Droste
- Department of Biology, Loyola University Chicago, Chicago, IL, United States of America
| | | | - Edwin Chaharbakhshi
- Department of Biology, Loyola University Chicago, Chicago, IL, United States of America
| | - Emily R. Temple-Wood
- Department of Biology, Loyola University Chicago, Chicago, IL, United States of America
| | - Jennifer C. Jemc
- Department of Biology, Loyola University Chicago, Chicago, IL, United States of America
- * E-mail:
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34
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Fairchild MJ, Yang L, Goodwin K, Tanentzapf G. Occluding Junctions Maintain Stem Cell Niche Homeostasis in the Fly Testes. Curr Biol 2016; 26:2492-2499. [PMID: 27546574 DOI: 10.1016/j.cub.2016.07.012] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2016] [Revised: 05/23/2016] [Accepted: 07/08/2016] [Indexed: 12/16/2022]
Abstract
Stem cells can be controlled by their local microenvironment, known as the stem cell niche. The Drosophila testes contain a morphologically distinct niche called the hub, composed of a cluster of between 8 and 20 cells known as hub cells, which contact and regulate germline stem cells (GSCs) and somatic cyst stem cells (CySCs). Both hub cells and CySCs originate from somatic gonadal precursor cells during embryogenesis, but whereas hub cells, once specified, cease all mitotic activity, CySCs remain mitotic into adulthood [1, 2]. Cyst cells, derived from the CySCs, first encapsulate the germline and then, using occluding junctions, form an isolating permeability barrier [3]. This barrier promotes germline differentiation by excluding niche-derived stem cell maintenance factors. Here, we show that the somatic permeability barrier is also required to regulate stem cell niche homeostasis. Loss of occluding junction components in the somatic cells results in hub overgrowth. Enlarged hubs are active and recruit more GSCs and CySCs to the niche. Surprisingly, hub growth results from depletion of occluding junction components in cyst cells, not from depletion in the hub cells themselves. Moreover, hub growth is caused by incorporation of cells that previously expressed markers for cyst cells and not by hub cell proliferation. Importantly, depletion of occluding junctions disrupts Notch and mitogen-activated protein kinase (MAPK) signaling, and hub overgrowth defects are partially rescued by modulation of either signaling pathway. Overall, these data show that occluding junctions shape the signaling environment between the soma and the germline in order to maintain niche homeostasis.
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Affiliation(s)
- Michael J Fairchild
- Department of Cellular and Physiological Sciences, University of British Columbia, 2350 Health Sciences Mall, Vancouver, BC V6T 1Z3, Canada
| | - Lulu Yang
- Department of Cellular and Physiological Sciences, University of British Columbia, 2350 Health Sciences Mall, Vancouver, BC V6T 1Z3, Canada
| | - Katharine Goodwin
- Department of Cellular and Physiological Sciences, University of British Columbia, 2350 Health Sciences Mall, Vancouver, BC V6T 1Z3, Canada
| | - Guy Tanentzapf
- Department of Cellular and Physiological Sciences, University of British Columbia, 2350 Health Sciences Mall, Vancouver, BC V6T 1Z3, Canada.
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35
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Barton LJ, Lovander KE, Pinto BS, Geyer PK. Drosophila male and female germline stem cell niches require the nuclear lamina protein Otefin. Dev Biol 2016; 415:75-86. [PMID: 27174470 DOI: 10.1016/j.ydbio.2016.05.001] [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] [Received: 09/01/2015] [Revised: 04/28/2016] [Accepted: 05/02/2016] [Indexed: 12/11/2022]
Abstract
The nuclear lamina is an extensive protein network that underlies the inner nuclear envelope. This network includes the LAP2-emerin-MAN1-domain (LEM-D) protein family, proteins that share an association with the chromatin binding protein Barrier-to-autointegration factor (BAF). Loss of individual LEM-D proteins causes progressive, tissue-restricted diseases, known as laminopathies. Mechanisms associated with laminopathies are not yet understood. Here we present our studies of one of the Drosophila nuclear lamina LEM-D proteins, Otefin (Ote), a homologue of emerin. Previous studies have shown that Ote is autonomously required for the survival of female germline stem cells (GSCs). We demonstrate that Ote is also required for survival of somatic cells in the ovarian niche, with loss of Ote causing a decrease in cap cell number and altered signal transduction. We show germ cell-restricted expression of Ote rescues these defects, revealing a non-autonomous function for Ote in niche maintenance and emphasizing that GSCs contribute to the maintenance of their own niches. Further, we investigate the requirement of Ote in the male fertility. We show that ote mutant males become prematurely sterile as they age. Parallel to observations in females, this sterility is associated with GSC loss and changes in somatic cells of the niche, phenotypes that are largely rescued by germ cell-restricted Ote expression. Taken together, our studies demonstrate that Ote is required autonomously for survival of two stem cell populations, as well as non-autonomously for maintenance of two somatic niches. Finally, our data add to growing evidence that LEM-D proteins have critical roles in stem cell survival and tissue homeostasis.
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Affiliation(s)
- Lacy J Barton
- Department of Biochemistry, University of Iowa, Iowa City, IA 52242, USA
| | - Kaylee E Lovander
- Department of Biochemistry, University of Iowa, Iowa City, IA 52242, USA
| | - Belinda S Pinto
- Department of Biochemistry, University of Iowa, Iowa City, IA 52242, USA
| | - Pamela K Geyer
- Department of Biochemistry, University of Iowa, Iowa City, IA 52242, USA.
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36
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Kotov AA, Olenkina OM, Kibanov MV, Olenina LV. RNA helicase Belle (DDX3) is essential for male germline stem cell maintenance and division in Drosophila. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2016; 1863:1093-105. [PMID: 26876306 DOI: 10.1016/j.bbamcr.2016.02.006] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/14/2015] [Revised: 01/19/2016] [Accepted: 02/09/2016] [Indexed: 01/08/2023]
Abstract
The present study showed that RNA helicase Belle (DDX3) was required intrinsically for mitotic progression and survival of germline stem cells (GSCs) and spermatogonial cells in the Drosophila melanogaster testes. We found that deficiency of Belle in the male germline resulted in a strong germ cell loss phenotype. Early germ cells are lost through cell death, whereas somatic hub and cyst cell populations are maintained. The observed phenotype is related to that of the human Sertoli Cell-Only Syndrome caused by the loss of DBY (DDX3) expression in the human testes and results in a complete lack of germ cells with preservation of somatic Sertoli cells. We found the hallmarks of mitotic G2 delay in early germ cells of the larval testes of bel mutants. Both mitotic cyclins, A and B, are markedly reduced in the gonads of bel mutants. Transcription levels of cycB and cycA decrease significantly in the testes of hypomorph bel mutants. Overexpression of Cyclin B in the germline partially rescues germ cell survival, mitotic progression and fertility in the bel-RNAi knockdown testes. Taken together, these results suggest that a role of Belle in GSC maintenance and regulation of early germ cell divisions is associated with the expression control of mitotic cyclins.
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Affiliation(s)
- Alexei A Kotov
- Laboratory of Biochemical Genetics of Animals, Institute of Molecular Genetics, Russian Academy of Sciences, Kurchatov Sq. 2, Moscow 123182, Russia
| | - Oxana M Olenkina
- Laboratory of Biochemical Genetics of Animals, Institute of Molecular Genetics, Russian Academy of Sciences, Kurchatov Sq. 2, Moscow 123182, Russia
| | - Mikhail V Kibanov
- Laboratory of Biochemical Genetics of Animals, Institute of Molecular Genetics, Russian Academy of Sciences, Kurchatov Sq. 2, Moscow 123182, Russia
| | - Ludmila V Olenina
- Laboratory of Biochemical Genetics of Animals, Institute of Molecular Genetics, Russian Academy of Sciences, Kurchatov Sq. 2, Moscow 123182, Russia.
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37
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Ma Q, de Cuevas M, Matunis EL. Chinmo is sufficient to induce male fate in somatic cells of the adult Drosophila ovary. Development 2016; 143:754-63. [PMID: 26811385 DOI: 10.1242/dev.129627] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2015] [Accepted: 01/16/2016] [Indexed: 01/08/2023]
Abstract
Sexual identity is continuously maintained in specific differentiated cell types long after sex determination occurs during development. In the adult Drosophila testis, the putative transcription factor Chronologically inappropriate morphogenesis (Chinmo) acts with the canonical male sex determinant DoublesexM (Dsx(M)) to maintain the male identity of somatic cyst stem cells and their progeny. Here we find that ectopic expression of chinmo is sufficient to induce a male identity in adult ovarian somatic cells, but it acts through a Dsx(M)-independent mechanism. Conversely, the feminization of the testis somatic stem cell lineage caused by loss of chinmo is enhanced by expression of the canonical female sex determinant Dsx(F), indicating that chinmo acts in parallel with the canonical sex determination pathway to maintain the male identity of testis somatic cells. Consistent with this finding, ectopic expression of female sex determinants in the adult testis disrupts tissue morphology. The miRNA let-7 downregulates chinmo in many contexts, and ectopic expression of let-7 in the adult testis is sufficient to recapitulate the chinmo loss-of-function phenotype, but we find no apparent phenotypes upon removal of let-7 in the adult ovary or testis. Our finding that chinmo is necessary and sufficient to promote a male identity in adult gonadal somatic cells suggests that the sexual identity of somatic cells can be reprogrammed in the adult Drosophila ovary as well as in the testis.
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Affiliation(s)
- Qing Ma
- Department of Cell Biology, Johns Hopkins University School of Medicine, 725 N. Wolfe Street, Baltimore, MD 21205, USA
| | - Margaret de Cuevas
- Department of Cell Biology, Johns Hopkins University School of Medicine, 725 N. Wolfe Street, Baltimore, MD 21205, USA
| | - Erika L Matunis
- Department of Cell Biology, Johns Hopkins University School of Medicine, 725 N. Wolfe Street, Baltimore, MD 21205, USA
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38
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Barr J, Yakovlev KV, Shidlovskii Y, Schedl P. Establishing and maintaining cell polarity with mRNA localization in Drosophila. Bioessays 2016; 38:244-53. [PMID: 26773560 DOI: 10.1002/bies.201500088] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
How cell polarity is established and maintained is an important question in diverse biological contexts. Molecular mechanisms used to localize polarity proteins to distinct domains are likely context-dependent and provide a feedback loop in order to maintain polarity. One such mechanism is the localized translation of mRNAs encoding polarity proteins, which will be the focus of this review and may play a more important role in the establishment and maintenance of polarity than is currently known. Localized translation of mRNAs encoding polarity proteins can be used to establish polarity in response to an external signal, and to maintain polarity by local production of polarity determinants. The importance of this mechanism is illustrated by recent findings, including orb2-dependent localized translation of aPKC mRNA at the apical end of elongating spermatid tails in the Drosophila testis, and the apical localization of stardust A mRNA in Drosophila follicle and embryonic epithelia.
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Affiliation(s)
- Justinn Barr
- Department of Molecular Biology, Princeton University, Princeton, NJ, USA
| | - Konstantin V Yakovlev
- Laboratory of Gene Expression Regulation in Development, Institute of Gene Biology RAS, Moscow, Russia.,A.V. Zhirmunsky Institute of Marine Biology, FEB RAS Laboratory of Cytotechnology, Vladivostok, Russia
| | - Yulii Shidlovskii
- Laboratory of Gene Expression Regulation in Development, Institute of Gene Biology RAS, Moscow, Russia
| | - Paul Schedl
- Department of Molecular Biology, Princeton University, Princeton, NJ, USA.,Laboratory of Gene Expression Regulation in Development, Institute of Gene Biology RAS, Moscow, Russia
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39
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Yu J, Lan X, Chen X, Yu C, Xu Y, Liu Y, Xu L, Fan HY, Tong C. Protein synthesis and degradation are critical to regulate germline stem cell homeostasis in Drosophila testes. Development 2016; 143:2930-45. [DOI: 10.1242/dev.134247] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2015] [Accepted: 07/11/2016] [Indexed: 12/14/2022]
Abstract
The homeostasis of self-renewal and differentiation in stem cells is strictly controlled by intrinsic signals and their niche. We conducted a large-scale RNA interference (RNAi) screen in Drosophila testes and identified 221 genes required for germline stem cell (GSC) maintenance or differentiation. Knockdown of these genes in transit-amplifying spermatogonia and cyst cells further revealed various phenotypes. Complex analysis uncovered that many of the identified genes are involved in key steps of protein synthesis and degradation. A group of genes that are required for mRNA splicing and protein translation contributes to both GSC self-renewal and early germ cell differentiation. Loss of genes in protein degradation pathway in cyst cells leads to testis tumor with overproliferated germ cells. Importantly, in the Cullin 4-Ring E3 ubiquitin ligase (CRL4) complex, we identified multiple proteins that are critical to GSC self-renewal. pic/DDB1, the linker protein of CRL4, is not only required for GSC self-renewal in flies but also for maintenance of spermatogonial stem cells (SSCs) in mice.
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Affiliation(s)
- Jun Yu
- Life Sciences Institute and Innovation Center for Cell Signaling Network, Zhejiang University, Hangzhou 310058, China
- State Key Laboratory of Reproductive Medicine, Nanjing Medical University, Nanjing 210029, China
- Department of Histology and Embryology, Nanjing Medical University, Nanjing 210029, China
| | - Xiang Lan
- Life Sciences Institute and Innovation Center for Cell Signaling Network, Zhejiang University, Hangzhou 310058, China
| | - Xia Chen
- State Key Laboratory of Reproductive Medicine, Nanjing Medical University, Nanjing 210029, China
| | - Chao Yu
- Life Sciences Institute and Innovation Center for Cell Signaling Network, Zhejiang University, Hangzhou 310058, China
| | - Yiwen Xu
- Life Sciences Institute and Innovation Center for Cell Signaling Network, Zhejiang University, Hangzhou 310058, China
| | - Yujuan Liu
- Life Sciences Institute and Innovation Center for Cell Signaling Network, Zhejiang University, Hangzhou 310058, China
- State Key Laboratory of Reproductive Medicine, Nanjing Medical University, Nanjing 210029, China
- Department of Histology and Embryology, Nanjing Medical University, Nanjing 210029, China
| | - Lingna Xu
- Life Sciences Institute and Innovation Center for Cell Signaling Network, Zhejiang University, Hangzhou 310058, China
| | - Heng-Yu Fan
- Life Sciences Institute and Innovation Center for Cell Signaling Network, Zhejiang University, Hangzhou 310058, China
| | - Chao Tong
- Life Sciences Institute and Innovation Center for Cell Signaling Network, Zhejiang University, Hangzhou 310058, China
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40
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Xie J, Wooten M, Tran V, Chen BC, Pozmanter C, Simbolon C, Betzig E, Chen X. Histone H3 Threonine Phosphorylation Regulates Asymmetric Histone Inheritance in the Drosophila Male Germline. Cell 2015; 163:920-33. [PMID: 26522592 DOI: 10.1016/j.cell.2015.10.002] [Citation(s) in RCA: 64] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2015] [Revised: 08/08/2015] [Accepted: 09/22/2015] [Indexed: 12/11/2022]
Abstract
A long-standing question concerns how stem cells maintain their identity through multiple divisions. Previously, we reported that pre-existing and newly synthesized histone H3 are asymmetrically distributed during Drosophila male germline stem cell (GSC) asymmetric division. Here, we show that phosphorylation at threonine 3 of H3 (H3T3P) distinguishes pre-existing versus newly synthesized H3. Converting T3 to the unphosphorylatable residue alanine (H3T3A) or to the phosphomimetic aspartate (H3T3D) disrupts asymmetric H3 inheritance. Expression of H3T3A or H3T3D specifically in early-stage germline also leads to cellular defects, including GSC loss and germline tumors. Finally, compromising the activity of the H3T3 kinase Haspin enhances the H3T3A but suppresses the H3T3D phenotypes. These studies demonstrate that H3T3P distinguishes sister chromatids enriched with distinct pools of H3 in order to coordinate asymmetric segregation of "old" H3 into GSCs and that tight regulation of H3T3 phosphorylation is required for male germline activity.
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Affiliation(s)
- Jing Xie
- Department of Biology, Johns Hopkins University, Baltimore, MD 21218, USA
| | - Matthew Wooten
- Department of Biology, Johns Hopkins University, Baltimore, MD 21218, USA
| | - Vuong Tran
- Department of Biology, Johns Hopkins University, Baltimore, MD 21218, USA
| | - Bi-Chang Chen
- HHMI, Janelia Research Campus, 19700 Helix Drive, Ashburn, VA 20147, USA
| | - Caitlin Pozmanter
- Department of Biology, Johns Hopkins University, Baltimore, MD 21218, USA
| | - Christine Simbolon
- Department of Biology, Johns Hopkins University, Baltimore, MD 21218, USA
| | - Eric Betzig
- HHMI, Janelia Research Campus, 19700 Helix Drive, Ashburn, VA 20147, USA
| | - Xin Chen
- Department of Biology, Johns Hopkins University, Baltimore, MD 21218, USA.
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41
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Tarayrah L, Li Y, Gan Q, Chen X. Epigenetic regulator Lid maintains germline stem cells through regulating JAK-STAT signaling pathway activity. Biol Open 2015; 4:1518-27. [PMID: 26490676 PMCID: PMC4728359 DOI: 10.1242/bio.013961] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Signaling pathways and epigenetic mechanisms have both been shown to play essential roles in regulating stem cell activity. While the role of either mechanism in this regulation is well established in multiple stem cell lineages, how the two mechanisms interact to regulate stem cell activity is not as well understood. Here we report that in the Drosophila testis, an H3K4me3-specific histone demethylase encoded by little imaginal discs (lid) maintains germline stem cell (GSC) mitotic index and prevents GSC premature differentiation. Lid is required in germ cells for proper expression of the Stat92E transcription factor, the downstream effector of the Janus kinase signal transducer and activator of transcription (JAK-STAT) signaling pathway. Our findings support a germ cell autonomous role for the JAK-STAT pathway in maintaining GSCs and place Lid as an upstream regulator of this pathway. Our study provides new insights into the biological functions of a histone demethylase in vivo and sheds light on the interaction between epigenetic mechanisms and signaling pathways in regulating stem cell activities. Summary: This study provides new insights into the biological functions of a histone demethylase and sheds light on the interaction between epigenetic mechanisms and signaling pathways in regulating stem cell activities.
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Affiliation(s)
- Lama Tarayrah
- Department of Biology, 3400 North Charles Street, The Johns Hopkins University, Baltimore, MD 21218-2685, USA
| | - Yuping Li
- Department of Biology, 3400 North Charles Street, The Johns Hopkins University, Baltimore, MD 21218-2685, USA
| | - Qiang Gan
- Department of Biology, 3400 North Charles Street, The Johns Hopkins University, Baltimore, MD 21218-2685, USA
| | - Xin Chen
- Department of Biology, 3400 North Charles Street, The Johns Hopkins University, Baltimore, MD 21218-2685, USA
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42
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Abstract
Stem cells are necessary for the maintenance of many adult tissues. Signals within the stem cell microenvironment, or niche, regulate the self-renewal and differentiation capability of these cells. Misregulation of these signals through mutation or damage can lead to overgrowth or depletion of different stem cell pools. In this review, we focus on the Drosophila testis and ovary, both of which contain well-defined niches, as well as the mouse testis, which has become a more approachable stem cell system with recent technical advances. We discuss the signals that regulate gonadal stem cells in their niches, how these signals mediate self-renewal and differentiation under homeostatic conditions, and how stress, whether from mutations or damage, can cause changes in cell fate and drive stem cell competition.
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Affiliation(s)
- Leah Joy Greenspan
- Department of Cell Biology, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205; , ,
| | - Margaret de Cuevas
- Department of Cell Biology, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205; , ,
| | - Erika Matunis
- Department of Cell Biology, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205; , ,
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Yang H, Yamashita YM. The regulated elimination of transit-amplifying cells preserves tissue homeostasis during protein starvation in Drosophila testis. Development 2015; 142:1756-66. [PMID: 25968311 DOI: 10.1242/dev.122663] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
How tissues adapt to varying nutrient conditions is of fundamental importance for robust tissue homeostasis throughout the life of an organism, but the underlying mechanisms are poorly understood. Here, we show that Drosophila testis responds to protein starvation by eliminating transit-amplifying spermatogonia (SG) while maintaining a reduced pool of actively proliferating germline stem cells (GSCs). During protein starvation, SG die in a manner that is mediated by the apoptosis of somatic cyst cells (CCs) that encapsulate SG and regulate their development. Strikingly, GSCs cannot be maintained during protein starvation when CC-mediated SG death is inhibited, leading to an irreversible collapse of tissue homeostasis. We propose that the regulated elimination of transit-amplifying cells is essential to preserve stem cell function and tissue homeostasis during protein starvation.
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Affiliation(s)
- Heiko Yang
- Life Sciences Institute, University of Michigan, Ann Arbor, MI 48109-2219, USA
| | - Yukiko M Yamashita
- Life Sciences Institute, University of Michigan, Ann Arbor, MI 48109-2219, USA Department of Cell and Developmental Biology, University of Michigan, Ann Arbor, MI 48109-2216, USA Howard Hughes Medical Institute, University of Michigan, Ann Arbor, MI 48109-2216, USA
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44
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Smendziuk CM, Messenberg A, Vogl AW, Tanentzapf G. Bi-directional gap junction-mediated soma-germline communication is essential for spermatogenesis. Development 2015; 142:2598-609. [PMID: 26116660 DOI: 10.1242/dev.123448] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2015] [Accepted: 06/12/2015] [Indexed: 01/25/2023]
Abstract
Soma-germline interactions play conserved essential roles in regulating cell proliferation, differentiation, patterning and homeostasis in the gonad. In the Drosophila testis, secreted signalling molecules of the JAK-STAT, Hedgehog, BMP and EGF pathways are used to mediate soma-germline communication. Here, we demonstrate that gap junctions may also mediate direct, bi-directional signalling between the soma and germ line. When gap junctions between the soma and germ line are disrupted, germline differentiation is blocked and germline stem cells are not maintained. In the soma, gap junctions are required to regulate proliferation and differentiation. Localization and RNAi-mediated knockdown studies reveal that gap junctions in the fly testis are heterotypic channels containing Zpg (Inx4) and Inx2 on the germ line and the soma side, respectively. Overall, our results show that bi-directional gap junction-mediated signalling is essential to coordinate the soma and germ line to ensure proper spermatogenesis in Drosophila. Moreover, we show that stem cell maintenance and differentiation in the testis are directed by gap junction-derived cues.
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Affiliation(s)
- Christopher M Smendziuk
- Department of Cellular and Physiological Sciences, 2350 Health Sciences Mall, University of British Columbia, Vancouver, Canada V6T 1Z3
| | - Anat Messenberg
- Department of Cellular and Physiological Sciences, 2350 Health Sciences Mall, University of British Columbia, Vancouver, Canada V6T 1Z3
| | - A Wayne Vogl
- Department of Cellular and Physiological Sciences, 2350 Health Sciences Mall, University of British Columbia, Vancouver, Canada V6T 1Z3
| | - Guy Tanentzapf
- Department of Cellular and Physiological Sciences, 2350 Health Sciences Mall, University of British Columbia, Vancouver, Canada V6T 1Z3
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45
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A Niche for GFRα1-Positive Spermatogonia in the Terminal Segments of the Seminiferous Tubules in Hamster Testes. Stem Cells 2015; 33:2811-24. [DOI: 10.1002/stem.2065] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2014] [Accepted: 04/20/2015] [Indexed: 01/15/2023]
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46
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Dubruille R, Loppin B. Protection of Drosophila chromosome ends through minimal telomere capping. J Cell Sci 2015; 128:1969-81. [PMID: 25908850 DOI: 10.1242/jcs.167825] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2014] [Accepted: 03/18/2015] [Indexed: 01/05/2023] Open
Abstract
In Drosophila, telomere-capping proteins have the remarkable capacity to recognize chromosome ends in a sequence-independent manner. This epigenetic protection is essential to prevent catastrophic ligations of chromosome extremities. Interestingly, capping proteins occupy a large telomere chromatin domain of several kilobases; however, the functional relevance of this to end protection is unknown. Here, we investigate the role of the large capping domain by manipulating HOAP (encoded by caravaggio) capping-protein expression in the male germ cells, where telomere protection can be challenged without compromising viability. We show that the exhaustion of HOAP results in a dramatic reduction of other capping proteins at telomeres, including K81 [encoded by ms(3)K81], which is essential for male fertility. Strikingly however, we demonstrate that, although capping complexes are barely detected in HOAP-depleted male germ cells, telomere protection and male fertility are not dramatically affected. Our study thus demonstrates that efficient protection of Drosophila telomeres can be achieved with surprisingly low amounts of capping complexes. We propose that these complexes prevent fusions by acting at the very extremity of chromosomes, reminiscent of the protection conferred by extremely short telomeric arrays in yeast or mammalian systems.
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Affiliation(s)
- Raphaëlle Dubruille
- Centre de Génétique et de Physiologie Moléculaire et Cellulaire, CNRS UMR 5534, Université Claude Bernard Lyon 1, Université de Lyon, 69100 Villeurbanne, France
| | - Benjamin Loppin
- Centre de Génétique et de Physiologie Moléculaire et Cellulaire, CNRS UMR 5534, Université Claude Bernard Lyon 1, Université de Lyon, 69100 Villeurbanne, France
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Newton ILG, Savytskyy O, Sheehan KB. Wolbachia utilize host actin for efficient maternal transmission in Drosophila melanogaster. PLoS Pathog 2015; 11:e1004798. [PMID: 25906062 PMCID: PMC4408098 DOI: 10.1371/journal.ppat.1004798] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2015] [Accepted: 03/11/2015] [Indexed: 11/23/2022] Open
Abstract
Wolbachia pipientis is a ubiquitous, maternally transmitted bacterium that infects the germline of insect hosts. Estimates are that Wolbachia infect nearly 40% of insect species on the planet, making it the most prevalent infection on Earth. The bacterium, infamous for the reproductive phenotypes it induces in arthropod hosts, has risen to recent prominence due to its use in vector control. Wolbachia infection prevents the colonization of vectors by RNA viruses, including Drosophila C virus and important human pathogens such as Dengue and Chikungunya. Here we present data indicating that Wolbachia utilize the host actin cytoskeleton during oogenesis for persistence within and transmission between Drosophila melanogaster generations. We show that phenotypically wild type flies heterozygous for cytoskeletal mutations in Drosophila profilin (chic(221/+) and chic(1320/+)) or villin (qua(6-396/+)) either clear a Wolbachia infection, or result in significantly reduced infection levels. This reduction of Wolbachia is supported by PCR evidence, Western blot results and cytological examination. This phenotype is unlikely to be the result of maternal loading defects, defects in oocyte polarization, or germline stem cell proliferation, as the flies are phenotypically wild type in egg size, shape, and number. Importantly, however, heterozygous mutant flies exhibit decreased total G-actin in the ovary, compared to control flies and chic(221) heterozygous mutants exhibit decreased expression of profilin. Additionally, RNAi knockdown of profilin during development decreases Wolbachia titers. We analyze evidence in support of alternative theories to explain this Wolbachia phenotype and conclude that our results support the hypothesis that Wolbachia utilize the actin skeleton for efficient transmission and maintenance within Drosophila.
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Affiliation(s)
- Irene L. G. Newton
- Department of Biology, Indiana University, Bloomington, Indiana, United States of America
| | - Oleksandr Savytskyy
- Department of Biology, Indiana University, Bloomington, Indiana, United States of America
| | - Kathy B. Sheehan
- Department of Biology, Indiana University, Bloomington, Indiana, United States of America
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Bonfini A, Wilkin MB, Baron M. Reversible regulation of stem cell niche size associated with dietary control of Notch signalling. BMC DEVELOPMENTAL BIOLOGY 2015; 15:8. [PMID: 25637382 PMCID: PMC4320563 DOI: 10.1186/s12861-015-0059-8] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/04/2014] [Accepted: 01/21/2015] [Indexed: 01/08/2023]
Abstract
Background Stem cells can respond to environmental and physiological inputs to adaptively remodel tissues. Little is known about whether stem cell niches are similarly responsive. The Drosophila ovary germline stem cell (GSC) niche is a well-studied model, which is comprised of cap cells that provide anchorage and maintenance signals for GSCs to maintain oogenesis. Previous studies have shown a strong link between diet and the regulation of oogenesis, making this a useful model system in which to investigate dietary regulation of the niche and its associated stem cells. Results We show that the Drosophila ovary GSC cap cell niche is a dynamic structure, which can contract and expand in fluctuating dietary conditions. Cap cells are lost when adult flies are shifted to nutrient poor diet and are restored after returning flies to nutrient-rich medium. Notch signalling in cap and escort cells is similarly reduced and restored by dietary shifts to nutrient poor and rich media. In old flies decreased Notch signalling is associated with decreased robustness of the niche to dietary changes. We demonstrated using a Notch temperature sensitive allele that removal and restoration of Notch signalling also leads to a reduction and re-expansion of the niche. Changes in niche size were not associated with apoptosis or cell division. We identified two distinct roles for Notch in the adult germarium. Notch can act in cap cells to prevent their loss while activation of Notch in the flanking escort cells results in expansion of the niche. Conclusions We provide evidence that dietary changes alone are sufficient to alter Notch signalling and reversibly change niche size in the adult in wild type flies. We show Notch acts in different cells to maintain and re-expand the niche and propose a model in which cell fate transitions between cap cells and flanking somatic cells accounts for niche dynamics. These findings reveal an unexpected reversible plasticity of the GSC niche whose responses provide an integrated read out of the physiological status of the fly that is modulated by diet and age. Electronic supplementary material The online version of this article (doi:10.1186/s12861-015-0059-8) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Alessandro Bonfini
- Faculty of Life Sciences, Michael Smith Building, Oxford Road, University of Manchester, Manchester, M13 9PT, UK.
| | - Marian B Wilkin
- Faculty of Life Sciences, Michael Smith Building, Oxford Road, University of Manchester, Manchester, M13 9PT, UK.
| | - Martin Baron
- Faculty of Life Sciences, Michael Smith Building, Oxford Road, University of Manchester, Manchester, M13 9PT, UK.
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Qian Y, Ng CL, Schulz C. CSN maintains the germline cellular microenvironment and controls the level of stem cell genes via distinct CRLs in testes of Drosophila melanogaster. Dev Biol 2014; 398:68-79. [PMID: 25459658 DOI: 10.1016/j.ydbio.2014.11.014] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2014] [Accepted: 11/13/2014] [Indexed: 12/25/2022]
Abstract
Stem cells and their daughters are often associated with and depend on cues from their cellular microenvironment. In Drosophila testes, each Germline Stem Cell (GSC) contacts apical hub cells and is enclosed by cytoplasmic extensions from two Cyst Stem Cells (CySCs). Each GSC daughter becomes enclosed by cytoplasmic extensions from two CySC daughters, called cyst cells. CySC fate depends on an Unpaired (Upd) signal from the hub cells, which activates the Janus Kinase and Signal Transducer and Activator of Transcription (Jak/STAT) pathway in the stem cells. Germline enclosure depends on Epidermal Growth Factor (EGF) signals from the germline to the somatic support cells. Expression of RNA-hairpins against subunits of the COnstitutively Photomorphogenic-9- (COP9-) signalosome (CSN) in somatic support cells disrupted germline enclosure. Furthermore, CSN-depleted somatic support cells in the CySC position next to the hub had reduced levels of the Jak/STAT effectors Zinc finger homeotic-1 (Zfh-1) and Chronologically inappropriate morphogenesis (Chinmo). Knockdown of CSN in the somatic support cells does not disrupt EGF and Upd signal transduction as downstream signal transducers, phosphorylated STAT (pSTAT) and phosphorylated Mitogen Activated Protein Kinase (pMAPK), were still localized to the somatic support cell nuclei. The CSN modifies fully formed Cullin RING ubiquitin ligase (CRL) complexes to regulate selective proteolysis. Reducing cullin2 (cul2) from the somatic support cells disrupted germline enclosure, while reducing cullin1 (cul1) from the somatic support cells led to a low level of Chinmo. We propose that different CRLs enable the responses of somatic support cells to Upd and EGF.
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Affiliation(s)
- Yue Qian
- (a)University of Georgia, Department of Cellular Biology, Athens, GA 30602, USA; Ripon College, Department of Biology, Ripon, WI 54971, USA
| | - Chun L Ng
- (a)University of Georgia, Department of Cellular Biology, Athens, GA 30602, USA
| | - Cordula Schulz
- (a)University of Georgia, Department of Cellular Biology, Athens, GA 30602, USA.
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The Jak-STAT target Chinmo prevents sex transformation of adult stem cells in the Drosophila testis niche. Dev Cell 2014; 31:474-86. [PMID: 25453558 DOI: 10.1016/j.devcel.2014.10.004] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2014] [Revised: 08/29/2014] [Accepted: 10/03/2014] [Indexed: 12/22/2022]
Abstract
Local signals maintain adult stem cells in many tissues. Whether the sexual identity of adult stem cells must also be maintained was not known. In the adult Drosophila testis niche, local Jak-STAT signaling promotes somatic cyst stem cell (CySC) renewal through several effectors, including the putative transcription factor Chronologically inappropriate morphogenesis (Chinmo). Here, we find that Chinmo also prevents feminization of CySCs. Chinmo promotes expression of the canonical male sex determination factor DoublesexM (Dsx(M)) within CySCs and their progeny, and ectopic expression of DsxM in the CySC lineage partially rescues the chinmo sex transformation phenotype, placing Chinmo upstream of Dsx(M). The Dsx homolog DMRT1 prevents the male-to-female conversion of differentiated somatic cells in the adult mammalian testis, but its regulation is not well understood. Our work indicates that sex maintenance occurs in adult somatic stem cells and that this highly conserved process is governed by effectors of niche signals. PAPERCLIP:
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