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Wilkin MB, Whiteford R, Akbar T, Hosseini-Alghaderi S, Revici R, Carbery AM, Baron M. The First Defined Null Allele of the Notch Regulator, a Suppressor of Deltex: Uncovering Its Novel Roles in Drosophila melanogaster Oogenesis. Biomolecules 2024; 14:522. [PMID: 38785929 PMCID: PMC11118177 DOI: 10.3390/biom14050522] [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: 03/12/2024] [Revised: 04/19/2024] [Accepted: 04/23/2024] [Indexed: 05/25/2024] Open
Abstract
Suppressor of deltex (Su(dx)) is a Drosophila melanogaster member of the NEDD4 family of the HECT domain E3 ubiquitin ligases. Su(dx) acts as a regulator of Notch endocytic trafficking, promoting Notch lysosomal degradation and the down-regulation of both ligand-dependent and ligand-independent signalling, the latter involving trafficking through the endocytic pathway and activation of the endo/lysosomal membrane. Mutations of Su(dx) result in developmental phenotypes in the Drosophila wing that reflect increased Notch signalling, leading to gaps in the specification of the wing veins, and Su(dx) functions to provide the developmental robustness of Notch activity to environmental temperature shifts. The full developmental functions of Su(dx) are unclear; however, this is due to a lack of a clearly defined null allele. Here we report the first defined null mutation of Su(dx), generated by P-element excision, which removes the complete open reading frame. We show that the mutation is recessive-viable, with the Notch gain of function phenotypes affecting wing vein and leg development. We further uncover new roles for Su(dx) in Drosophila oogenesis, where it regulates interfollicular stalk formation, egg chamber separation and germline cyst enwrapment by the follicle stem cells. Interestingly, while the null allele exhibited a gain in Notch activity during oogenesis, the previously described Su(dx)SP allele, which carries a seven amino acid in-frame deletion, displayed a Notch loss of function phenotypes and an increase in follicle stem cell turnover. This is despite both alleles displaying similar Notch gain of function in wing development. We attribute this unexpected context-dependent outcome of Su(dx)sp being due to the partial retention of function by the intact C2 and WW domain regions of the protein. Our results extend our understanding of the developmental role of Su(dx) in the tissue renewal and homeostasis of the Drosophila ovary and illustrate the importance of examining an allelic series of mutations to fully understand developmental functions.
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Affiliation(s)
| | | | | | | | | | | | - Martin Baron
- Manchester Academic Health Science Centre, School of Biological Sciences, University of Manchester, Michael Smith Building and Oxford Rd., Manchester M13 9PT, UK
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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: 1] [Impact Index Per Article: 1.0] [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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3
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Cui Z, Wei H, Goding C, Cui R. Stem cell heterogeneity, plasticity, and regulation. Life Sci 2023; 334:122240. [PMID: 37925141 DOI: 10.1016/j.lfs.2023.122240] [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: 09/08/2023] [Revised: 10/30/2023] [Accepted: 10/31/2023] [Indexed: 11/06/2023]
Abstract
As a population of homogeneous cells with both self-renewal and differentiation potential, stem cell pools are highly compartmentalized and contain distinct subsets that exhibit stable but limited heterogeneity during homeostasis. However, their striking plasticity is showcased under natural or artificial stress, such as injury, transplantation, cancer, and aging, leading to changes in their phenotype, constitution, metabolism, and function. The complex and diverse network of cell-extrinsic niches and signaling pathways, together with cell-intrinsic genetic and epigenetic regulators, tightly regulate both the heterogeneity during homeostasis and the plasticity under perturbation. Manipulating these factors offers better control of stem cell behavior and a potential revolution in the current state of regenerative medicine. However, disruptions of normal regulation by genetic mutation or excessive plasticity acquisition may contribute to the formation of tumors. By harnessing innovative techniques that enhance our understanding of stem cell heterogeneity and employing novel approaches to maximize the utilization of stem cell plasticity, stem cell therapy holds immense promise for revolutionizing the future of medicine.
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Affiliation(s)
- Ziyang Cui
- Department of Dermatology and Venerology, Peking University First Hospital, Beijing 100034, China.
| | - Hope Wei
- Department of Biology, Boston University, 5 Cummington Mall, Boston, MA 02215, United States of America
| | - Colin Goding
- Ludwig Institute for Cancer Research, Nuffield Department of Clinical Medicine, University of Oxford, Headington, Oxford OX37DQ, UK
| | - Rutao Cui
- Skin Disease Research Institute, The 2nd Hospital, Zhejiang University School of Medicine, Hangzhou 310058, China
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4
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Melamed D, Choi A, Reilein A, Tavaré S, Kalderon D. Spatial regulation of Drosophila ovarian Follicle Stem Cell division rates and cell cycle transitions. PLoS Genet 2023; 19:e1010965. [PMID: 37747936 PMCID: PMC10553835 DOI: 10.1371/journal.pgen.1010965] [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: 10/14/2022] [Revised: 10/05/2023] [Accepted: 09/11/2023] [Indexed: 09/27/2023] Open
Abstract
Drosophila ovarian Follicle Stem Cells (FSCs) present a favorable paradigm for understanding how stem cell division and differentiation are balanced in communities where those activities are independent. FSCs also allow exploration of how this balance is integrated with spatial stem cell heterogeneity. Posterior FSCs become proliferative Follicle Cells (FCs), while anterior FSCs become quiescent Escort Cells (ECs) at about one fourth the frequency. A single stem cell can nevertheless produce both FCs and ECs because it can move between anterior and posterior locations. Studies based on EdU incorporation to approximate division rates suggested that posterior FSCs divide faster than anterior FSCs. However, direct measures of cell cycle times are required to ascertain whether FC output requires a net flow of FSCs from anterior to posterior. Here, by using live imaging and FUCCI cell-cycle reporters, we measured absolute division rates. We found that posterior FSCs cycle more than three times faster than anterior FSCs and produced sufficient new cells to match FC production. H2B-RFP dilution studies supported different cycling rates according to A/P location and facilitated live imaging, showing A/P exchange of FSCs in both directions, consistent with the dynamic equilibrium inferred from division rate measurements. Inversely graded Wnt and JAK-STAT pathway signals regulate FSC differentiation to ECs and FCs. JAK-STAT promotes both differentiation to FCs and FSC cycling, affording some coordination of these activities. When JAK-STAT signaling was manipulated to be spatially uniform, the ratio of posterior to anterior division rates was reduced but remained substantial, showing that graded JAK-STAT signaling only partly explains the graded cycling of FSCs. By using FUCCI markers, we found a prominent G2/M cycling restriction of posterior FSCs together with an A/P graded G1/S restriction, that JAK-STAT signaling promotes both G1/S and G2/M transitions, and that PI3 kinase signaling principally stimulates the G2/M transition.
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Affiliation(s)
- David Melamed
- Department of Biological Sciences, Columbia University, New York, New York State, United States of America
| | - Aaron Choi
- Department of Biological Sciences, Columbia University, New York, New York State, United States of America
| | - Amy Reilein
- Department of Biological Sciences, Columbia University, New York, New York State, United States of America
| | - Simon Tavaré
- Department of Biological Sciences, Columbia University, New York, New York State, United States of America
- Irving Institute for Cancer Dynamics & Department of Statistics, Columbia University, New York, New York State, United States of America
| | - Daniel Kalderon
- Department of Biological Sciences, Columbia University, New York, New York State, United States of America
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5
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Dong Z, Pang L, Liu Z, Sheng Y, Li X, Thibault X, Reilein A, Kalderon D, Huang J. Single-cell expression profile of Drosophila ovarian follicle stem cells illuminates spatial differentiation in the germarium. BMC Biol 2023; 21:143. [PMID: 37340484 PMCID: PMC10283321 DOI: 10.1186/s12915-023-01636-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2022] [Accepted: 05/26/2023] [Indexed: 06/22/2023] Open
Abstract
BACKGROUND How stem cell populations are organized and regulated within adult tissues is important for understanding cancer origins and for developing cell replacement strategies. Paradigms such as mammalian gut stem cells and Drosophila ovarian follicle stem cells (FSC) are characterized by population asymmetry, in which stem cell division and differentiation are separately regulated processes. These stem cells behave stochastically regarding their contributions to derivative cells and also exhibit dynamic spatial heterogeneity. Drosophila FSCs provide an excellent model for understanding how a community of active stem cells maintained by population asymmetry is regulated. Here, we use single-cell RNA sequencing to profile the gene expression patterns of FSCs and their immediate derivatives to investigate heterogeneity within the stem cell population and changes associated with differentiation. RESULTS We describe single-cell RNA sequencing studies of a pre-sorted population of cells that include FSCs and the neighboring cell types, escort cells (ECs) and follicle cells (FCs), which they support. Cell-type assignment relies on anterior-posterior (AP) location within the germarium. We clarify the previously determined location of FSCs and use spatially targeted lineage studies as further confirmation. The scRNA profiles among four clusters are consistent with an AP progression from anterior ECs through posterior ECs and then FSCs, to early FCs. The relative proportion of EC and FSC clusters are in good agreement with the prevalence of those cell types in a germarium. Several genes with graded profiles from ECs to FCs are highlighted as candidate effectors of the inverse gradients of the two principal signaling pathways, Wnt and JAK-STAT, that guide FSC differentiation and division. CONCLUSIONS Our data establishes an important resource of scRNA-seq profiles for FSCs and their immediate derivatives that is based on precise spatial location and functionally established stem cell identity, and facilitates future genetic investigation of regulatory interactions guiding FSC behavior.
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Affiliation(s)
- Zhi Dong
- Institute of Insect Sciences, Ministry of Agriculture Key Lab of Molecular Biology of Crop Pathogens and Insect Pests, College of Agriculture and Biotechnology, Zhejiang University, Hangzhou, 310058, China
| | - Lan Pang
- Institute of Insect Sciences, Ministry of Agriculture Key Lab of Molecular Biology of Crop Pathogens and Insect Pests, College of Agriculture and Biotechnology, Zhejiang University, Hangzhou, 310058, China
| | - Zhiguo Liu
- Institute of Insect Sciences, Ministry of Agriculture Key Lab of Molecular Biology of Crop Pathogens and Insect Pests, College of Agriculture and Biotechnology, Zhejiang University, Hangzhou, 310058, China
| | - Yifeng Sheng
- Institute of Insect Sciences, Ministry of Agriculture Key Lab of Molecular Biology of Crop Pathogens and Insect Pests, College of Agriculture and Biotechnology, Zhejiang University, Hangzhou, 310058, China
| | - Xiaoping Li
- Department of Hepatic Surgery and Liver Transplantation Center of the Third Affiliated Hospital, Organ Transplantation Institute, Sun Yat-Sen University, Guangzhou, 510630, Guangdong, China
| | - Xavier Thibault
- Department of Biological Sciences, Columbia University, New York, NY, USA
| | - Amy Reilein
- Department of Biological Sciences, Columbia University, New York, NY, USA
| | - Daniel Kalderon
- Department of Biological Sciences, Columbia University, New York, NY, USA.
| | - Jianhua Huang
- Institute of Insect Sciences, Ministry of Agriculture Key Lab of Molecular Biology of Crop Pathogens and Insect Pests, College of Agriculture and Biotechnology, Zhejiang University, Hangzhou, 310058, China.
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6
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Galasso A, Xu DC, Hill C, Iakovleva D, Stefana MI, Baena‐Lopez LA. Non-apoptotic caspase activation ensures the homeostasis of ovarian somatic stem cells. EMBO Rep 2023; 24:e51716. [PMID: 37039000 PMCID: PMC10240206 DOI: 10.15252/embr.202051716] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2020] [Revised: 02/22/2023] [Accepted: 03/14/2023] [Indexed: 04/12/2023] Open
Abstract
Current evidence has associated caspase activation with the regulation of basic cellular functions without causing apoptosis. Malfunction of non-apoptotic caspase activities may contribute to specific neurological disorders, metabolic diseases, autoimmune conditions and cancers. However, our understanding of non-apoptotic caspase functions remains limited. Here, we show that non-apoptotic caspase activation prevents the intracellular accumulation of the Patched receptor in autophagosomes and the subsequent Patched-dependent induction of autophagy in Drosophila follicular stem cells. These events ultimately sustain Hedgehog signalling and the physiological properties of ovarian somatic stem cells and their progeny under moderate thermal stress. Importantly, our key findings are partially conserved in ovarian somatic cells of human origin. These observations attribute to caspases a pro-survival role under certain cellular conditions.
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Affiliation(s)
- Alessia Galasso
- Faculty of Medicine CentreImperial College London, South Kensington CampusLondonUK
| | - Derek Cui Xu
- Sir William Dunn School of PathologyUniversity of OxfordOxfordUK
| | - Claire Hill
- School of Medicine, Dentistry and Biomedical SciencesQueen's University Belfast MedicineBelfastUK
| | - Daria Iakovleva
- Center for Regenerative MedicineUniversity of EdinburghEdinburghUK
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7
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Rincón-Ortega L, Valencia-Expósito A, Kabanova A, González-Reyes A, Martin-Bermudo MD. Integrins control epithelial stem cell proliferation in the Drosophila ovary by modulating the Notch pathway. Front Cell Dev Biol 2023; 11:1114458. [PMID: 36926523 PMCID: PMC10011466 DOI: 10.3389/fcell.2023.1114458] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2022] [Accepted: 02/07/2023] [Indexed: 03/08/2023] Open
Abstract
Cell proliferation and differentiation show a remarkable inverse relationship. The temporal coupling between cell cycle withdrawal and differentiation of stem cells (SCs) is crucial for epithelial tissue growth, homeostasis and regeneration. Proliferation vs. differentiation SC decisions are often controlled by the surrounding microenvironment, of which the basement membrane (BM; a specialized form of extracellular matrix surrounding cells and tissues), is one of its main constituents. Years of research have shown that integrin-mediated SC-BM interactions regulate many aspects of SC biology, including the proliferation-to-differentiation switch. However, these studies have also demonstrated that the SC responses to interactions with the BM are extremely diverse and depend on the cell type and state and on the repertoire of BM components and integrins involved. Here, we show that eliminating integrins from the follicle stem cells (FSCs) of the Drosophila ovary and their undifferentiated progeny increases their proliferation capacity. This results in an excess of various differentiated follicle cell types, demonstrating that cell fate determination can occur in the absence of integrins. Because these phenotypes are similar to those found in ovaries with decreased laminin levels, our results point to a role for the integrin-mediated cell-BM interactions in the control of epithelial cell division and subsequent differentiation. Finally, we show that integrins regulate proliferation by restraining the activity of the Notch/Delta pathway during early oogenesis. Our work increases our knowledge of the effects of cell-BM interactions in different SC types and should help improve our understanding of the biology of SCs and exploit their therapeutic potential.
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Affiliation(s)
- Lourdes Rincón-Ortega
- Centro Andaluz de Biología del Desarrollo, CSIC/Universidad Pablo de Olavide/JA, Sevilla, Spain
| | | | - Anna Kabanova
- Centro Andaluz de Biología del Desarrollo, CSIC/Universidad Pablo de Olavide/JA, Sevilla, Spain
| | - Acaimo González-Reyes
- Centro Andaluz de Biología del Desarrollo, CSIC/Universidad Pablo de Olavide/JA, Sevilla, Spain
| | - Maria D Martin-Bermudo
- Centro Andaluz de Biología del Desarrollo, CSIC/Universidad Pablo de Olavide/JA, Sevilla, Spain
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8
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Lee EH, Zinshteyn D, Miglo F, Wang MQ, Reinach J, Chau CM, Grosstephan JM, Correa I, Costa K, Vargas A, Johnson A, Longo SM, Alexander JI, O'Reilly AM. Sequential events during the quiescence to proliferation transition establish patterns of follicle cell differentiation in the Drosophila ovary. Biol Open 2023; 12:bio059625. [PMID: 36524613 PMCID: PMC9867896 DOI: 10.1242/bio.059625] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2022] [Accepted: 12/07/2022] [Indexed: 12/23/2022] Open
Abstract
Stem cells cycle between periods of quiescence and proliferation to promote tissue health. In Drosophila ovaries, quiescence to proliferation transitions of follicle stem cells (FSCs) are exquisitely feeding-dependent. Here, we demonstrate feeding-dependent induction of follicle cell differentiation markers, eyes absent (Eya) and castor (Cas) in FSCs, a patterning process that does not depend on proliferation induction. Instead, FSCs extend micron-scale cytoplasmic projections that dictate Eya-Cas patterning. We identify still life and sickie as necessary and sufficient for FSC projection growth and Eya-Cas induction. Our results suggest that sequential, interdependent events establish long-term differentiation patterns in follicle cell precursors, independently of FSC proliferation induction.
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Affiliation(s)
- Eric H. Lee
- Molecular Therapeutics Program, Fox Chase Cancer Center, Philadelphia, PA 19111, USA
- Immersion Science Program, Fox Chase Cancer Center, Philadelphia, PA 19111, USA
| | - Daniel Zinshteyn
- Molecular Therapeutics Program, Fox Chase Cancer Center, Philadelphia, PA 19111, USA
| | - Fred Miglo
- Molecular Therapeutics Program, Fox Chase Cancer Center, Philadelphia, PA 19111, USA
- Immersion Science Program, Fox Chase Cancer Center, Philadelphia, PA 19111, USA
| | - Melissa Q. Wang
- Molecular Therapeutics Program, Fox Chase Cancer Center, Philadelphia, PA 19111, USA
- Immersion Science Program, Fox Chase Cancer Center, Philadelphia, PA 19111, USA
| | - Jessica Reinach
- Immersion Science Program, Fox Chase Cancer Center, Philadelphia, PA 19111, USA
| | - Cindy M. Chau
- Immersion Science Program, Fox Chase Cancer Center, Philadelphia, PA 19111, USA
| | | | - Iliana Correa
- Immersion Science Program, Fox Chase Cancer Center, Philadelphia, PA 19111, USA
| | - Kelly Costa
- Immersion Science Program, Fox Chase Cancer Center, Philadelphia, PA 19111, USA
| | - Alberto Vargas
- Molecular Therapeutics Program, Fox Chase Cancer Center, Philadelphia, PA 19111, USA
| | - Aminah Johnson
- Molecular Therapeutics Program, Fox Chase Cancer Center, Philadelphia, PA 19111, USA
| | - Sheila M. Longo
- Molecular Therapeutics Program, Fox Chase Cancer Center, Philadelphia, PA 19111, USA
- Drexel University College of Medicine, Molecular and Cellular Biology and Genetics Graduate Program, Philadelphia, PA 19129, USA
| | - Jennifer I. Alexander
- Molecular Therapeutics Program, Fox Chase Cancer Center, Philadelphia, PA 19111, USA
- Immersion Science Program, Fox Chase Cancer Center, Philadelphia, PA 19111, USA
| | - Alana M. O'Reilly
- Molecular Therapeutics Program, Fox Chase Cancer Center, Philadelphia, PA 19111, USA
- Immersion Science Program, Fox Chase Cancer Center, Philadelphia, PA 19111, USA
- Drexel University College of Medicine, Molecular and Cellular Biology and Genetics Graduate Program, Philadelphia, PA 19129, USA
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Siddall NA, Casagranda F, Johanson TM, Dominado N, Heaney J, Sutherland JM, McLaughlin EA, Hime GR. MiMIC analysis reveals an isoform specific role for Drosophila Musashi in follicle stem cell maintenance and escort cell function. Cell Death Dis 2022; 8:455. [DOI: 10.1038/s41420-022-01245-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2022] [Revised: 10/30/2022] [Accepted: 10/31/2022] [Indexed: 11/13/2022]
Abstract
AbstractThe Drosophila ovary is regenerated from germline and somatic stem cell populations that have provided fundamental conceptual understanding on how adult stem cells are regulated within their niches. Recent ovarian transcriptomic studies have failed to identify mRNAs that are specific to follicle stem cells (FSCs), suggesting that their fate may be regulated post-transcriptionally. We have identified that the RNA-binding protein, Musashi (Msi) is required for maintaining the stem cell state of FSCs. Loss of msi function results in stem cell loss, due to a change in differentiation state, indicated by upregulation of Lamin C in the stem cell population. In msi mutant ovaries, Lamin C upregulation was also observed in posterior escort cells that interact with newly formed germ cell cysts. Mutant somatic cells within this region were dysfunctional, as evidenced by the presence of germline cyst collisions, fused egg chambers and an increase in germ cell cyst apoptosis. The msi locus produces two classes of mRNAs (long and short). We show that FSC maintenance and escort cell function specifically requires the long transcripts, thus providing the first evidence of isoform-specific regulation in a population of Drosophila epithelial cells. We further demonstrate that although male germline stem cells have previously been shown to require Msi function to prevent differentiation this is not the case for female germline stem cells, indicating that these similar stem cell types have different requirements for Msi, in addition to the differential use of Msi isoforms between soma and germline. In summary, we show that different isoforms of the Msi RNA-binding protein are expressed in specific cell populations of the ovarian stem cell niche where Msi regulates stem cell differentiation, niche cell function and subsequent germ cell survival and differentiation.
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10
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Riparbelli MG, Persico V, Callaini G. Cell-to-Cell Interactions during Early Drosophila Oogenesis: An Ultrastructural Analysis. Cells 2022; 11:cells11172658. [PMID: 36078066 PMCID: PMC9454453 DOI: 10.3390/cells11172658] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2022] [Revised: 08/24/2022] [Accepted: 08/25/2022] [Indexed: 11/27/2022] Open
Abstract
Drosophila oogenesis requires the subsequent growth of distinct egg chambers each containing a group of sixteen germline cells surrounded by a simple epithelium of follicle cells. The oocyte occupies a posterior position within the germ cells, thus giving a distinct asymmetry to the egg chamber. Although this disposition is critical for the formation of the anterior–posterior axis of the embryo, the interplay between somatic and germ cells during the early stages of oogenesis remains an open question. We uncover by stage 2, when the egg chambers leaved the germarium, some unique spatial interactions between the posterior follicle cells and the oocyte. These interactions are restricted to the surface of the oocyte over the centriole cluster that formed during early oogenesis. Moreover, the posterior follicle cells in front of the oocyte display a convoluted apical membrane with extensive contacts, whereas the other follicle cells have a flat apical surface without obvious surface protrusions. In addition, the germ cells located at the posterior end of the egg chamber have very elongated protrusions that come into contact with each other or with facing follicle cells. These observations point to distinct polarization events during early oogenesis supporting previous molecular data of an inherent asymmetry between the anterior and the posterior regions of the egg chambers.
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11
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Thompson JW, Michel MFV, Phillips BT. Centrosomal Enrichment and Proteasomal Degradation of SYS-1/β-catenin Requires the Microtubule Motor Dynein. Mol Biol Cell 2022; 33:ar42. [PMID: 35196020 PMCID: PMC9282011 DOI: 10.1091/mbc.e22-02-0031] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
The Caenorhabditis elegans Wnt/β-catenin asymmetry (WβA) pathway utilizes asymmetric regulation of SYS-1/β-catenin and POP-1/TCF coactivators. WβA differentially regulates gene expression during cell fate decisions, specifically by asymmetric localization of determinants in mother cells to produce daughters biased toward their appropriate cell fate. Despite the induction of asymmetry, β-catenin localizes symmetrically to mitotic centrosomes in both mammals and C. elegans. Owing to the mitosis-specific localization of SYS-1 to centrosomes and enrichment of SYS-1 at kinetochore microtubules when SYS-1 centrosomal loading is disrupted, we investigated active trafficking in SYS-1 centrosomal localization. Here, we demonstrate that trafficking by microtubule motor dynein is required to maintain SYS-1 centrosomal enrichment, by dynein RNA interference (RNAi)-mediated decreases in SYS-1 centrosomal enrichment and by temperature-sensitive allele of the dynein heavy chain. Conversely, we observe depletion of microtubules by nocodazole treatment or RNAi of dynein-proteasome adapter ECPS-1 exhibits increased centrosomal enrichment of SYS-1. Moreover, disruptions to SYS-1 or negative regulator microtubule trafficking are sufficient to significantly exacerbate SYS-1 dependent cell fate misspecifications. We propose a model whereby retrograde microtubule-mediated trafficking enables SYS-1 enrichment at centrosomes, enhancing its eventual proteasomal degradation. These studies support the link between centrosomal localization and enhancement of proteasomal degradation, particularly for proteins not generally considered “centrosomal.”
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Affiliation(s)
| | - Maria F Valdes Michel
- Interdisciplinary Graduate Program in Genetics, University of Iowa, Iowa City, IA 52242-1324
| | - Bryan T Phillips
- Department of Biology, University of Iowa, Iowa City, IA 52242-1324.,Interdisciplinary Graduate Program in Genetics, University of Iowa, Iowa City, IA 52242-1324
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12
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Waghmare I, Page-McCaw A. Regulation of Wnt distribution and function by Drosophila glypicans. J Cell Sci 2022; 135:274233. [PMID: 35112708 PMCID: PMC8918805 DOI: 10.1242/jcs.259405] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
The extracellular distribution of secreted Wnt proteins is crucial for their ability to induce a response in target cells at short and long ranges to ensure proper development. Wnt proteins are evolutionarily conserved ligands that are lipid-modified, and their hydrophobic nature interferes with their solubility in the hydrophilic extracellular environment. This raises the question of how Wnt proteins spread extracellularly despite their lipid modifications, which are essential for both their secretion and function. Seminal studies on Drosophila Wingless (Wg), a prototypical Wnt, have discovered multiple mechanisms by which Wnt proteins spread. A central theme emerges from these studies: the Wnt lipid moiety is shielded from the aqueous environment, allowing the ligands to spread and remain viable for signaling. Wnt distribution in vivo is primarily facilitated by glypicans, which are cell-surface heparan sulfate proteoglycans, and recent studies have further provided mechanistic insight into how glypicans facilitate Wnt distribution. In this Review, we discuss the many diverse mechanisms of Wnt distribution, with a particular focus on glypican-mediated mechanisms.
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Abstract
A simple, universal and fundamental definition of adult stem cell communities is proposed. Key principles of cell lineage methods for defining adult stem cell numbers, locations and behaviors are critically evaluated, emphasizing the imperatives of capturing the full spectrum of individual stem cell behaviors, examining a variety of experimental time periods and avoiding unwarranted assumptions. The focus is first on defining fundamentals and then addresses stem cell heterogeneity, potential hierarchies and how individual cells serve the function of a stem cell community.
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14
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Reilein A, Kogan HV, Misner R, Park KS, Kalderon D. Adult stem cells and niche cells segregate gradually from common precursors that build the adult Drosophila ovary during pupal development. eLife 2021; 10:69749. [PMID: 34590579 PMCID: PMC8536258 DOI: 10.7554/elife.69749] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2021] [Accepted: 09/29/2021] [Indexed: 12/31/2022] Open
Abstract
Production of proliferative follicle cells (FCs) and quiescent escort cells (ECs) by follicle stem cells (FSCs) in adult Drosophila ovaries is regulated by niche signals from anterior (cap cells, ECs) and posterior (polar FCs) sources. Here we show that ECs, FSCs, and FCs develop from common pupal precursors, with different fates acquired by progressive separation of cells along the AP axis and a graded decline in anterior cell proliferation. ECs, FSCs, and most FCs derive from intermingled cell (IC) precursors interspersed with germline cells. Precursors also accumulate posterior to ICs before engulfing a naked germline cyst projected out of the germarium to form the first egg chamber and posterior polar FC signaling center. Thus, stem and niche cells develop in appropriate numbers and spatial organization through regulated proliferative expansion together with progressive establishment of spatial signaling cues that guide adult cell behavior, rather than through rigid early specification events.
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Affiliation(s)
- Amy Reilein
- Department of Biological Sciences, Columbia University, New York, United States
| | - Helen V Kogan
- Department of Biological Sciences, Columbia University, New York, United States
| | - Rachel Misner
- Department of Biological Sciences, Columbia University, New York, United States
| | - Karen Sophia Park
- Department of Biological Sciences, Columbia University, New York, United States
| | - Daniel Kalderon
- Department of Biological Sciences, Columbia University, New York, United States
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15
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Slaidina M, Gupta S, Banisch TU, Lehmann R. A single-cell atlas reveals unanticipated cell type complexity in Drosophila ovaries. Genome Res 2021; 31:1938-1951. [PMID: 34389661 DOI: 10.1101/gr.274340.120] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2020] [Accepted: 08/09/2021] [Indexed: 11/24/2022]
Abstract
Organ function relies on the spatial organization and functional coordination of numerous cell types. The Drosophila ovary is a widely used model system to study the cellular activities underlying organ function, including stem cell regulation, cell signaling and epithelial morphogenesis. However, the relative paucity of cell type-specific reagents hinders investigation of molecular functions at the appropriate cellular resolution. Here, we used single-cell RNA sequencing to characterize all cell types of the stem cell compartment and early follicles of the Drosophila ovary. We computed transcriptional signatures and identified specific markers for nine states of germ cell differentiation, and 23 somatic cell types and subtypes. We uncovered an unanticipated diversity of escort cells, the somatic cells that directly interact with differentiating germline cysts. Three escort cell subtypes reside in discrete anatomical positions, and express distinct sets of secreted and transmembrane proteins, suggesting that diverse micro-environments support the progressive differentiation of germ cells. Finally, we identified 17 follicle cell subtypes, and characterized their transcriptional profiles. Altogether, we provide a comprehensive resource of gene expression, cell type-specific markers, spatial coordinates and functional predictions for 34 ovarian cell types and subtypes.
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Affiliation(s)
| | - Selena Gupta
- Skirball Institute, NYU Grossman School of Medicine
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16
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Correa I, Wang M, Lee EH, Ruiz-Whalen DM, O’Reilly AM, Singh T. Protocol for evaluating autophagy using LysoTracker staining in the epithelial follicle stem cells of the Drosophila ovary. STAR Protoc 2021; 2:100592. [PMID: 34169286 PMCID: PMC8209645 DOI: 10.1016/j.xpro.2021.100592] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022] Open
Abstract
We have outlined the approach of visualizing autophagy specifically in the epithelial follicle stem cells of the Drosophila ovary using the LysoTracker dye. The advantage of using this protocol is that it details several techniques, including ovary dissection, immunofluorescence, and western blotting, that positively identify autophagy changes in a very small population of cells. One of the limitations of this protocol is that it needs to be combined with other genetic manipulations and positive markers of the autophagy pathway. For complete details on the use and execution of this protocol, please refer to Singh et al., (2018).
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Affiliation(s)
- Iliana Correa
- Fox Chase Cancer Center, Philadelphia, PA 19111, USA
| | - Melissa Wang
- Fox Chase Cancer Center, Philadelphia, PA 19111, USA
| | - Eric H. Lee
- Fox Chase Cancer Center, Philadelphia, PA 19111, USA
| | | | | | - Tanu Singh
- Fox Chase Cancer Center, Philadelphia, PA 19111, USA
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17
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Wang X, LaFever KS, Waghmare I, Page-McCaw A. Extracellular spreading of Wingless is required for Drosophila oogenesis. PLoS Genet 2021; 17:e1009469. [PMID: 33798197 PMCID: PMC8046344 DOI: 10.1371/journal.pgen.1009469] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2020] [Revised: 04/14/2021] [Accepted: 03/05/2021] [Indexed: 11/18/2022] Open
Abstract
Recent studies have investigated whether the Wnt family of extracellular ligands can signal at long range, spreading from their source and acting as morphogens, or whether they signal only in a juxtacrine manner to neighboring cells. The original evidence for long-range Wnt signaling arose from studies of Wg, a Drosophila Wnt protein, which patterns the wing disc over several cell diameters from a central source of Wg ligand. However, the requirement of long-range Wg for patterning was called into question when it was reported that replacing the secreted protein Wg with a membrane-tethered version, NRT-Wg, results in flies with normally patterned wings. We and others previously reported that Wg spreads in the ovary about 50 μm or 5 cell diameters, from the cap cells to the follicle stem cells (FSCs) and that Wg stimulates FSC proliferation. We used the NRT-wg flies to analyze the consequence of tethering Wg to the cap cells. NRT-wg homozygous flies are sickly, but we found that hemizygous NRT-wg/null flies, carrying only one copy of tethered Wingless, were significantly healthier. Despite their overall improved health, these hemizygous flies displayed dramatic reductions in fertility and in FSC proliferation. Further, FSC proliferation was nearly undetectable when the wg locus was converted to NRT-wg only in adults, and the resulting germarium phenotype was consistent with a previously reported wg loss-of-function phenotype. We conclude that Wg protein spreads from its source cells in the germarium to promote FSC proliferation.
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Affiliation(s)
- Xiaoxi Wang
- Department of Cell and Developmental Biology, Program in Developmental Biology, Vanderbilt-Ingram Cancer Center, Vanderbilt University School of Medicine, Nashville, Tennessee, United States of America
| | - Kimberly S. LaFever
- Department of Cell and Developmental Biology, Program in Developmental Biology, Vanderbilt-Ingram Cancer Center, Vanderbilt University School of Medicine, Nashville, Tennessee, United States of America
| | - Indrayani Waghmare
- Department of Cell and Developmental Biology, Program in Developmental Biology, Vanderbilt-Ingram Cancer Center, Vanderbilt University School of Medicine, Nashville, Tennessee, United States of America
| | - Andrea Page-McCaw
- Department of Cell and Developmental Biology, Program in Developmental Biology, Vanderbilt-Ingram Cancer Center, Vanderbilt University School of Medicine, Nashville, Tennessee, United States of America
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18
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A Progressive Somatic Cell Niche Regulates Germline Cyst Differentiation in the Drosophila Ovary. Curr Biol 2021; 31:840-852.e5. [PMID: 33340458 DOI: 10.1016/j.cub.2020.11.053] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2020] [Revised: 10/02/2020] [Accepted: 11/18/2020] [Indexed: 12/20/2022]
Abstract
In the germarium of the Drosophila ovary, developing germline cysts are surrounded by a population of somatic escort cells that are known to function as the niche cells for germline differentiation;1 however, the underlying molecular mechanisms of this niche function remain poorly understood. Through single-cell gene expression profiling combined with genetic analyses, we here demonstrate that the escort cells can be spatially and functionally divided into two successive domains. The anterior escort cells (aECs) specifically produce ecdysone, which acts on the cystoblast to promote synchronous cell division, whereas the posterior escort cells (pECs) respond to ecdysone signaling and regulate soma-germline cell adhesion to promote the transition from 16-cell cyst-to-egg chamber formation. The patterning of the aEC and pEC domains is independent of the germline but is dependent on JAK/STAT signaling activity, which emanates from the posterior. Thus, a heterogeneous population of escort cells constitutes a stepwise niche environment to orchestrate cystoblast division and differentiation toward egg chamber formation.
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19
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A single-cell atlas and lineage analysis of the adult Drosophila ovary. Nat Commun 2020; 11:5628. [PMID: 33159074 PMCID: PMC7648648 DOI: 10.1038/s41467-020-19361-0] [Citation(s) in RCA: 55] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2020] [Accepted: 10/08/2020] [Indexed: 01/05/2023] Open
Abstract
The Drosophila ovary is a widely used model for germ cell and somatic tissue biology. Here we use single-cell RNA-sequencing (scRNA-seq) to build a comprehensive cell atlas of the adult Drosophila ovary that contains transcriptional profiles for every major cell type in the ovary, including the germline stem cells and their niche cells, follicle stem cells, and previously undescribed subpopulations of escort cells. In addition, we identify Gal4 lines with specific expression patterns and perform lineage tracing of subpopulations of escort cells and follicle cells. We discover that a distinct subpopulation of escort cells is able to convert to follicle stem cells in response to starvation or upon genetic manipulation, including knockdown of escargot, or overactivation of mTor or Toll signalling.
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20
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Melamed D, Kalderon D. Opposing JAK-STAT and Wnt signaling gradients define a stem cell domain by regulating differentiation at two borders. eLife 2020; 9:61204. [PMID: 33135631 PMCID: PMC7695452 DOI: 10.7554/elife.61204] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2020] [Accepted: 10/30/2020] [Indexed: 12/13/2022] Open
Abstract
Many adult stem cell communities are maintained by population asymmetry, where stochastic behaviors of multiple individual cells collectively result in a balance between stem cell division and differentiation. We investigated how this is achieved for Drosophila Follicle Stem Cells (FSCs) by spatially-restricted niche signals. FSCs produce transit-amplifying Follicle Cells (FCs) from their posterior face and quiescent Escort Cells (ECs) to their anterior. We show that JAK-STAT pathway activity, which declines from posterior to anterior, dictates the pattern of divisions over the FSC domain, promotes more posterior FSC locations and conversion to FCs, while opposing EC production. Wnt pathway activity declines from the anterior, promotes anterior FSC locations and EC production, and opposes FC production. The pathways combine to define a stem cell domain through concerted effects on FSC differentiation to ECs and FCs at either end of opposing signaling gradients, and impose a pattern of proliferation that matches derivative production.
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Affiliation(s)
- David Melamed
- Department of Biological Sciences, Columbia University, New York, United States
| | - Daniel Kalderon
- Department of Biological Sciences, Columbia University, New York, United States
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21
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Chanet S, Huynh JR. Collective Cell Sorting Requires Contractile Cortical Waves in Germline Cells. Curr Biol 2020; 30:4213-4226.e4. [PMID: 32916115 DOI: 10.1016/j.cub.2020.08.045] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2020] [Revised: 07/01/2020] [Accepted: 08/12/2020] [Indexed: 12/11/2022]
Abstract
Encapsulation of germline cells by layers of somatic cells forms the basic unit of female reproduction called primordial follicles in mammals and egg chambers in Drosophila. How germline and somatic tissues are coordinated for the morphogenesis of each separated unit remains poorly understood. Here, using improved live imaging of Drosophila ovaries, we uncovered periodic actomyosin waves at the cortex of germ cells. These contractile waves are associated with pressure release blebs, which project from germ cells into somatic cells. We demonstrate that these cortical activities, together with cadherin-based adhesion, are required to sort each germline cyst as one collective unit. Genetic perturbations of cortical contractility, bleb protrusion, or adhesion between germline and somatic cells induced encapsulation defects resulting from failures to encapsulate any germ cells, or the inclusion of too many germ cells per egg chamber, or even the mechanical split of germline cysts. Live-imaging experiments revealed that reducing contractility or adhesion in the germline reduced the stiffness of germline cysts and their proper anchoring to the somatic cells. Germline cysts can then be squeezed and passively pushed by constricting surrounding somatic cells, resulting in cyst splitting and cyst collisions during encapsulation. Increasing germline cysts activity or blocking somatic cell constriction movements can reveal active forward migration of germline cysts. Our results show that germ cells play an active role in physical coupling with somatic cells to produce the female gamete.
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Affiliation(s)
- Soline Chanet
- Center for Interdisciplinary Research in Biology, Collège de France, PSL Research University, CNRS/UMR 7241 - INSERM U1050, 11 Place Marcelin Berthelot, 75005 Paris, France
| | - Jean-René Huynh
- Center for Interdisciplinary Research in Biology, Collège de France, PSL Research University, CNRS/UMR 7241 - INSERM U1050, 11 Place Marcelin Berthelot, 75005 Paris, France.
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22
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Wen X, Wu Y, Awadasseid A, Tanaka Y, Zhang W. New Advances in Canonical Wnt/β-Catenin Signaling in Cancer. Cancer Manag Res 2020; 12:6987-6998. [PMID: 32821165 PMCID: PMC7418153 DOI: 10.2147/cmar.s258645] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2020] [Accepted: 07/19/2020] [Indexed: 12/16/2022] Open
Abstract
Wnt/β-catenin-mediated signaling is a key pathway regulating tissue growth and development, and tumorigenesis, and has received increasing attention in recent years. In addition to participating in healthy tissue and organ development, ectopic activation of the pathway can cause a variety of tumors and other pathologies. The pathway plays a critical role in many processes such as proliferation, differentiation, apoptosis, migration, invasion, epithelial–mesenchymal transition and cancer cell stemness. The importance of the Wnt signal is self-evident. This review describes the underlying mechanism of Wnt signaling pathway and highlights the latest findings on the relationship between Wnt signaling pathway and tumorigenesis. In addition, the potential relationship between miRNAs and Wnt signaling is presented. Furthermore, we discuss the intrinsic link between Wnt signaling and cancer cell stemness, which shed light on the malignant progression of tumor cells. Finally, cancer treatment strategies based on the canonical Wnt signaling pathway are summarized, hoping to help clinical development.
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Affiliation(s)
- Xiaolan Wen
- Laboratory of Chemical Biology and Molecular Drug Design, College of Pharmaceutical Science, Zhejiang University of Technology, Hangzhou 310014, People's Republic of China.,Laboratory of Molecular Immunology, Zhejiang Provincial Center for Disease Control and Prevention, Hangzhou 310051, People's Republic of China
| | - Yanling Wu
- Laboratory of Chemical Biology and Molecular Drug Design, College of Pharmaceutical Science, Zhejiang University of Technology, Hangzhou 310014, People's Republic of China.,Laboratory of Molecular Immunology, Zhejiang Provincial Center for Disease Control and Prevention, Hangzhou 310051, People's Republic of China
| | - Annoor Awadasseid
- Laboratory of Chemical Biology and Molecular Drug Design, College of Pharmaceutical Science, Zhejiang University of Technology, Hangzhou 310014, People's Republic of China.,Center for Natural Products Research, Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu, 610041, People's Republic of China
| | - Yoshimasa Tanaka
- Laboratory of Bioinformatics and Molecular Medicine, Center for Medical Innovation, Nagasaki University, Nagasaki, 852-8588, Japan
| | - Wen Zhang
- Laboratory of Chemical Biology and Molecular Drug Design, College of Pharmaceutical Science, Zhejiang University of Technology, Hangzhou 310014, People's Republic of China
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23
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Waghmare I, Wang X, Page-McCaw A. Dally-like protein sequesters multiple Wnt ligands in the Drosophila germarium. Dev Biol 2020; 464:88-102. [PMID: 32473955 DOI: 10.1016/j.ydbio.2020.05.004] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2019] [Revised: 05/02/2020] [Accepted: 05/11/2020] [Indexed: 12/20/2022]
Abstract
Cells in multicellular organisms rely on secreted ligands for development and morphogenesis. Several mechanisms modulate the availability and distribution of secreted ligands, determining their ability to signal locally and at long range from their source. One of these mechanisms is Dally-like protein (Dlp), a cell-surface glypican that exhibits biphasic functions in Drosophila wing discs, promoting Wg signaling at long-range from Wg source cells and inhibiting Wg signaling near source cells. In the germarium at the tip of the ovary, Dlp promotes long-range distribution of Wg from cap cells to follicle stem cells. However, the germarium also expresses other Wnts - Wnt2, Wnt4, and Wnt6 - that function locally in escort cells to promote oogenesis. Whether and how local functions of these Wnts are regulated remains unknown. Here we show that the dlp overexpression phenotype is multifaceted and phenocopies multiple Wnt loss-of-function phenotypes. Each aspect of dlp overexpression phenotype is suppressed by co-expression of individual Wnts, and the suppression pattern exhibited by each Wnt suggests that Wnts have functional specificity in the germarium. Further, dlp knockdown phenocopies Wnt gain-of-function phenotypes. Together these data show that Dlp inhibits the functions of each Wnt. All four Wnts co-immunoprecipitate with Dlp in S2R+ cells, suggesting that in the germarium, Dlp sequesters Wnts to inhibit local paracrine Wnt signaling. Our results indicate that Dlp modulates the availability of multiple extracellular Wnts for local paracrine Wnt signaling in the germarium.
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Affiliation(s)
- Indrayani Waghmare
- Department of Cell and Developmental Biology and Program in Developmental Biology, Vanderbilt University School of Medicine, Nashville, TN, 37232, USA.
| | - Xiaoxi Wang
- Department of Cell and Developmental Biology and Program in Developmental Biology, Vanderbilt University School of Medicine, Nashville, TN, 37232, USA
| | - Andrea Page-McCaw
- Department of Cell and Developmental Biology and Program in Developmental Biology, Vanderbilt University School of Medicine, Nashville, TN, 37232, USA
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24
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A system-level mechanistic explanation for asymmetric stem cell fates: Arabidopsis thaliana root niche as a study system. Sci Rep 2020; 10:3525. [PMID: 32103059 PMCID: PMC7044435 DOI: 10.1038/s41598-020-60251-8] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2019] [Accepted: 12/23/2019] [Indexed: 11/09/2022] Open
Abstract
Asymmetric divisions maintain long-term stem cell populations while producing new cells that proliferate and then differentiate. Recent reports in animal systems show that divisions of stem cells can be uncoupled from their progeny differentiation, and the outcome of a division could be influenced by microenvironmental signals. But the underlying system-level mechanisms, and whether this dynamics also occur in plant stem cell niches (SCN), remain elusive. This article presents a cell fate regulatory network model that contributes to understanding such mechanism and identify critical cues for cell fate transitions in the root SCN. Novel computational and experimental results show that the transcriptional regulator SHR is critical for the most frequent asymmetric division previously described for quiescent centre stem cells. A multi-scale model of the root tip that simulated each cell's intracellular regulatory network, and the dynamics of SHR intercellular transport as a cell-cell coupling mechanism, was developed. It revealed that quiescent centre cell divisions produce two identical cells, that may acquire different fates depending on the feedback between SHR's availability and the state of the regulatory network. Novel experimental data presented here validates our model, which in turn, constitutes the first proposed systemic mechanism for uncoupled SCN cell division and differentiation.
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25
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Hinnant TD, Merkle JA, Ables ET. Coordinating Proliferation, Polarity, and Cell Fate in the Drosophila Female Germline. Front Cell Dev Biol 2020; 8:19. [PMID: 32117961 PMCID: PMC7010594 DOI: 10.3389/fcell.2020.00019] [Citation(s) in RCA: 53] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2019] [Accepted: 01/10/2020] [Indexed: 01/05/2023] Open
Abstract
Gametes are highly specialized cell types produced by a complex differentiation process. Production of viable oocytes requires a series of precise and coordinated molecular events. Early in their development, germ cells are an interconnected group of mitotically dividing cells. Key regulatory events lead to the specification of mature oocytes and initiate a switch to the meiotic cell cycle program. Though the chromosomal events of meiosis have been extensively studied, it is unclear how other aspects of oocyte specification are temporally coordinated. The fruit fly, Drosophila melanogaster, has long been at the forefront as a model system for genetics and cell biology research. The adult Drosophila ovary continuously produces germ cells throughout the organism’s lifetime, and many of the cellular processes that occur to establish oocyte fate are conserved with mammalian gamete development. Here, we review recent discoveries from Drosophila that advance our understanding of how early germ cells balance mitotic exit with meiotic initiation. We discuss cell cycle control and establishment of cell polarity as major themes in oocyte specification. We also highlight a germline-specific organelle, the fusome, as integral to the coordination of cell division, cell polarity, and cell fate in ovarian germ cells. Finally, we discuss how the molecular controls of the cell cycle might be integrated with cell polarity and cell fate to maintain oocyte production.
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Affiliation(s)
- Taylor D Hinnant
- Department of Biology, East Carolina University, Greenville, NC, United States
| | - Julie A Merkle
- Department of Biology, University of Evansville, Evansville, IN, United States
| | - Elizabeth T Ables
- Department of Biology, East Carolina University, Greenville, NC, United States
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26
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Slaidina M, Banisch TU, Gupta S, Lehmann R. A single-cell atlas of the developing Drosophila ovary identifies follicle stem cell progenitors. Genes Dev 2020; 34:239-249. [PMID: 31919193 PMCID: PMC7000915 DOI: 10.1101/gad.330464.119] [Citation(s) in RCA: 41] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2019] [Accepted: 12/02/2019] [Indexed: 12/16/2022]
Abstract
Addressing the complexity of organogenesis at a system-wide level requires a complete understanding of adult cell types, their origin, and precursor relationships. The Drosophila ovary has been a model to study how coordinated stem cell units, germline, and somatic follicle stem cells maintain and renew an organ. However, lack of cell type-specific tools have limited our ability to study the origin of individual cell types and stem cell units. Here, we used a single-cell RNA sequencing approach to uncover all known cell types of the developing ovary, reveal transcriptional signatures, and identify cell type-specific markers for lineage tracing. Our study identifies a novel cell type corresponding to the elusive follicle stem cell precursors and predicts subtypes of known cell types. Altogether, we reveal a previously unanticipated complexity of the developing ovary and provide a comprehensive resource for the systematic analysis of ovary morphogenesis.
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Affiliation(s)
- Maija Slaidina
- Department of Cell Biology, Howard Hughes Medical Institute, Skirball Institute of Biomolecular Medicine, New York University School of Medicine, New York 10016, USA
| | - Torsten U Banisch
- Department of Cell Biology, Howard Hughes Medical Institute, Skirball Institute of Biomolecular Medicine, New York University School of Medicine, New York 10016, USA
| | - Selena Gupta
- Department of Cell Biology, Howard Hughes Medical Institute, Skirball Institute of Biomolecular Medicine, New York University School of Medicine, New York 10016, USA
| | - Ruth Lehmann
- Department of Cell Biology, Howard Hughes Medical Institute, Skirball Institute of Biomolecular Medicine, New York University School of Medicine, New York 10016, USA
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27
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Rust K, Nystul T. Signal transduction in the early Drosophila follicle stem cell lineage. CURRENT OPINION IN INSECT SCIENCE 2020; 37:39-48. [PMID: 32087562 PMCID: PMC7155752 DOI: 10.1016/j.cois.2019.11.005] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/29/2019] [Revised: 11/13/2019] [Accepted: 11/16/2019] [Indexed: 05/08/2023]
Abstract
The follicle stem cell (FSC) lineage in the Drosophila ovary is a highly informative model of in vivo epithelial stem cell biology. Studies over the past 30 years have identified roles for every major signaling pathway in the early FSC lineage. These pathways regulate a wide variety of cell behaviors, including self-renewal, proliferation, survival and differentiation. Studies of cell signaling in the follicle epithelium have provided new insights into how these cell behaviors are coordinated within an epithelial stem cell lineage and how signaling pathways interact with each other in the native, in vivo context of a living tissue. Here, we review these studies, with a particular focus on how these pathways specify differences between the FSCs and their daughter cells. We also describe common themes that have emerged from these studies, and highlight new research directions that have been made possible by the detailed understanding of the follicle epithelium.
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28
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Hayashi Y, Yoshinari Y, Kobayashi S, Niwa R. The regulation of Drosophila ovarian stem cell niches by signaling crosstalk. CURRENT OPINION IN INSECT SCIENCE 2020; 37:23-29. [PMID: 32087560 DOI: 10.1016/j.cois.2019.10.006] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/29/2019] [Revised: 10/06/2019] [Accepted: 10/30/2019] [Indexed: 06/10/2023]
Abstract
The Drosophila female ovary is an excellent model for investigating how multiple stem cell types are coordinately regulated in vivo. The ovary contains at least two stem cell types, germline stem cells (GSCs) and somatic follicular stem cells (FSCs). Although GSCs and FSCs are maintained within a distinct extra-cellular microenvironment, known as a niche, they share some common signaling molecules to generate their own niche. To properly maintain these stem cell types, understanding how signaling molecules are regulated is essential. In this review, we summarize the recent understanding of the mechanisms maintaining GSCs and FSCs from the perspective of growth factor regulation and discuss how these regulatory mechanisms contribute to stem cell maintenance, competition, and survival.
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Affiliation(s)
- Yoshiki Hayashi
- Life Science Center for Survival Dynamics (TARA), University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8577, Japan.
| | - Yuto Yoshinari
- Graduate School of Life and Environmental Science, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8572, Japan
| | - Satoru Kobayashi
- Life Science Center for Survival Dynamics (TARA), University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8577, Japan
| | - Ryusuke Niwa
- Life Science Center for Survival Dynamics (TARA), University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8577, Japan
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29
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Niwa R, Kai T. Editorial overview: Stem cells orchestrate oogenesis: a lesson from the fruit fly, Drosophila melanogaster. CURRENT OPINION IN INSECT SCIENCE 2020; 37:iii-v. [PMID: 32199590 DOI: 10.1016/j.cois.2020.03.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Affiliation(s)
- Ryusuke Niwa
- Life Science Center for Survival Dynamics, Tsukuba Advanced Research Alliance (TARA), University of Tsukuba, Tennodai 1-1-1, Tsukuba, Ibaraki 305-8577, Japan.
| | - Toshie Kai
- Graduate School of Frontier Biosciences, Osaka University, 1-3 Yamadaoka, Suita, Osaka 565-0871, Japan.
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30
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Sokolova OA, Mikhaleva EA, Kharitonov SL, Abramov YA, Gvozdev VA, Klenov MS. Special vulnerability of somatic niche cells to transposable element activation in Drosophila larval ovaries. Sci Rep 2020; 10:1076. [PMID: 31974416 PMCID: PMC6978372 DOI: 10.1038/s41598-020-57901-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2019] [Accepted: 01/07/2020] [Indexed: 01/09/2023] Open
Abstract
In the Drosophila ovary, somatic escort cells (ECs) form a niche that promotes differentiation of germline stem cell (GSC) progeny. The piRNA (Piwi-interacting RNA) pathway, which represses transposable elements (TEs), is required in ECs to prevent the accumulation of undifferentiated germ cells (germline tumor phenotype). The soma-specific piRNA cluster flamenco (flam) produces a substantial part of somatic piRNAs. Here, we characterized the biological effects of somatic TE activation on germ cell differentiation in flam mutants. We revealed that the choice between normal and tumorous phenotypes of flam mutant ovaries depends on the number of persisting ECs, which is determined at the larval stage. Accordingly, we found much more frequent DNA breaks in somatic cells of flam larval ovaries than in adult ECs. The absence of Chk2 or ATM checkpoint kinases dramatically enhanced oogenesis defects of flam mutants, in contrast to the germline TE-induced defects that are known to be mostly suppressed by сhk2 mutation. These results demonstrate a crucial role of checkpoint kinases in protecting niche cells against deleterious TE activation and suggest substantial differences between DNA damage responses in ovarian somatic and germ cells.
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Affiliation(s)
- Olesya A Sokolova
- Department of Molecular Genetics of the Cell, Institute of Molecular Genetics, Russian Academy of Sciences, 2 Kurchatov Sq., 123182, Moscow, Russian Federation
| | - Elena A Mikhaleva
- Department of Molecular Genetics of the Cell, Institute of Molecular Genetics, Russian Academy of Sciences, 2 Kurchatov Sq., 123182, Moscow, Russian Federation
| | - Sergey L Kharitonov
- Department of Molecular Genetics of the Cell, Institute of Molecular Genetics, Russian Academy of Sciences, 2 Kurchatov Sq., 123182, Moscow, Russian Federation
- Laboratory of Postgenomic Research, Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, 32 Vavilova St., 119991, Moscow, Russian Federation
| | - Yuri A Abramov
- Department of Molecular Genetics of the Cell, Institute of Molecular Genetics, Russian Academy of Sciences, 2 Kurchatov Sq., 123182, Moscow, Russian Federation
| | - Vladimir A Gvozdev
- Department of Molecular Genetics of the Cell, Institute of Molecular Genetics, Russian Academy of Sciences, 2 Kurchatov Sq., 123182, Moscow, Russian Federation
| | - Mikhail S Klenov
- Department of Molecular Genetics of the Cell, Institute of Molecular Genetics, Russian Academy of Sciences, 2 Kurchatov Sq., 123182, Moscow, Russian Federation.
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31
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Fadiga J, Nystul TG. The follicle epithelium in the Drosophila ovary is maintained by a small number of stem cells. eLife 2019; 8:e49050. [PMID: 31850843 PMCID: PMC6946398 DOI: 10.7554/elife.49050] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2019] [Accepted: 12/17/2019] [Indexed: 12/12/2022] Open
Abstract
The follicle stem cells (FSCs) in the Drosophila ovary are an important experimental model for the study of epithelial stem cell biology. Although decades of research support the conclusion that there are two FSCs per ovariole, a recent study used a novel clonal marking system to conclude that there are 15-16 FSCs per ovariole. We performed clonal analysis using both this novel clonal marking system and standard clonal marking systems, and identified several problems that may have contributed to the overestimate of FSC number. In addition, we developed new methods for accurately measuring clone size, and found that FSC clones produce, on average, half of the follicle cells in each ovariole. Our findings provide strong independent support for the conclusion that there are typically two active FSCs per ovariole, though they are consistent with up to four FSCs per germarium.
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Affiliation(s)
- Jocelyne Fadiga
- Department of AnatomyUniversity of California, San FranciscoSan FranciscoUnited States
- Department of OB/GYN-RS, Center for Reproductive SciencesUniversity of California, San FranciscoSan FranciscoUnited States
| | - Todd G Nystul
- Department of AnatomyUniversity of California, San FranciscoSan FranciscoUnited States
- Department of OB/GYN-RS, Center for Reproductive SciencesUniversity of California, San FranciscoSan FranciscoUnited States
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32
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Lobo-Pecellín M, Marín-Menguiano M, González-Reyes A. mastermind regulates niche ageing independently of the Notch pathway in the Drosophila ovary. Open Biol 2019; 9:190127. [PMID: 31744422 PMCID: PMC6893403 DOI: 10.1098/rsob.190127] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Proper stem cell activity in tissues ensures the correct balance between proliferation and differentiation, thus allowing tissue homeostasis and repair. The Drosophila ovary develops well-defined niches that contain on average 2–4 germline stem cells (GSCs), whose maintenance depends on systemic signals and local factors. A known player in the decline of tissue homeostasis is ageing, which correlates with the waning of resident stem cell populations. In Drosophila, ovaries from old females contain fewer GSCs than those from young flies. We isolated niche cells of aged ovaries, performed a transcriptomic analysis and identified mastermind (mam) as a factor for Drosophila ovarian niche functionality during ageing. We show that mam is upregulated in aged niche cells and that we can induce premature GSC loss by overexpressing mam in otherwise young niche cells. High mam levels in niche cells induce reduced Hedgehog amounts, a decrease in cadherin levels and a likely increase in reactive oxygen species, three scenarios known to provoke GSC loss. Mam is a canonical co-activator of the Notch pathway in many Drosophila tissues. However, we present evidence to support a Notch-independent role for mam in the ovarian germline niche.
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Affiliation(s)
- María Lobo-Pecellín
- Centro Andaluz de Biología del Desarrollo, CSIC/Universidad Pablo de Olavide/JA, Carretera de Utrera km 1, 41013 Sevilla, Spain
| | - Miriam Marín-Menguiano
- Centro Andaluz de Biología del Desarrollo, CSIC/Universidad Pablo de Olavide/JA, Carretera de Utrera km 1, 41013 Sevilla, Spain
| | - Acaimo González-Reyes
- Centro Andaluz de Biología del Desarrollo, CSIC/Universidad Pablo de Olavide/JA, Carretera de Utrera km 1, 41013 Sevilla, Spain
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33
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Reilein A, Cimetta E, Tandon NM, Kalderon D, Vunjak-Novakovic G. Live imaging of stem cells in the germarium of the Drosophila ovary using a reusable gas-permeable imaging chamber. Nat Protoc 2019; 13:2601-2614. [PMID: 30349048 DOI: 10.1038/s41596-018-0054-1] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Live imaging of stem cells and their support cells can be used to visualize cellular dynamics and fluctuations of intracellular signals, proteins, and organelles in order to better understand stem cell behavior in the niche. We describe a simple protocol for imaging stem cells in the Drosophila ovary that improves on alternative protocols in that flies of any age can be used, dissection is simplified because the epithelial sheath that surrounds each ovariole need not be removed, and ovarioles are imaged in a closed chamber with a large volume of medium that buffers oxygen, pH, and temperature. We also describe how to construct the imaging chamber, which can be easily modified and used to image other tissues and non-adherent cells. Imaging is limited by follicle cells moving out of the germarium in culture around the time of egg chamber budding; however, the epithelial sheath delays this abnormal cell migration. This protocol requires an hour to prepare the ovarioles, followed by half an hour on the confocal microscope to locate germaria and set z limits. Successful imaging time depends on germarial morphology at the time of dissection, but we suggest 10-11 h to encompass all specimens.
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Affiliation(s)
- Amy Reilein
- Department of Biological Sciences, Columbia University, New York, NY, USA.
| | - Elisa Cimetta
- Department of Industrial Engineering (DII), Padova University, Padua, Italy. .,Fondazione Istituto di Ricerca Pediatrica Città della Speranza, Corso Stati Uniti, Padua, Italy.
| | - Nina M Tandon
- EpiBone, Inc., Brooklyn, NY, USA.,Department of Electrical Engineering, The Cooper Union for the Advancement of Science and Art, New York, NY, USA
| | - Daniel Kalderon
- Department of Biological Sciences, Columbia University, New York, NY, USA
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Kim-Yip RP, Nystul TG. Wingless promotes EGFR signaling in follicle stem cells to maintain self-renewal. Development 2018; 145:dev.168716. [PMID: 30389852 DOI: 10.1242/dev.168716] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2018] [Accepted: 10/29/2018] [Indexed: 12/20/2022]
Abstract
Adult stem cell niche boundaries must be precisely maintained to facilitate the segregation of stem cell and daughter cell fates. However, the mechanisms that govern this process in epithelial tissues are not fully understood. In this study, we investigated the relationship between two signals, Wnt and EGFR, that are necessary for self-renewal of the epithelial follicle stem cells (FSCs) in the Drosophila ovary, but must be downregulated in cells that have exited the niche to allow for differentiation. We found that Wingless produced by inner germarial sheath (IGS) cells acts over a short distance to activate Wnt signaling in FSCs, and that movement across the FSC niche boundary is limited. In addition, we show that Wnt signaling functions genetically upstream of EGFR signaling by activating the expression of the EGFR ligand, Spitz, and that constitutive activation of EGFR partially rescues the self-renewal defect caused by loss of Wnt signaling. Collectively, our findings support a model in which the Wnt and EGFR pathways operate in a signaling hierarchy to promote FSC self-renewal.
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Affiliation(s)
- Rebecca P Kim-Yip
- Center for Reproductive Sciences, Departments of Anatomy and OB/GYN-RS, University of California, San Francisco, CA 94143-0452, USA
| | - Todd G Nystul
- Center for Reproductive Sciences, Departments of Anatomy and OB/GYN-RS, University of California, San Francisco, CA 94143-0452, USA
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35
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Singh T, Lee EH, Hartman TR, Ruiz-Whalen DM, O'Reilly AM. Opposing Action of Hedgehog and Insulin Signaling Balances Proliferation and Autophagy to Determine Follicle Stem Cell Lifespan. Dev Cell 2018; 46:720-734.e6. [PMID: 30197240 PMCID: PMC6159899 DOI: 10.1016/j.devcel.2018.08.008] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2017] [Revised: 06/07/2018] [Accepted: 08/09/2018] [Indexed: 10/28/2022]
Abstract
Egg production declines with age in many species, a process linked with stem cell loss. Diet-dependent signaling has emerged as critical for stem cell maintenance during aging. Follicle stem cells (FSCs) in the Drosophila ovary are exquisitely responsive to diet-induced signals including Hedgehog (Hh) and insulin-IGF signaling (IIS), entering quiescence in the absence of nutrients and initiating proliferation rapidly upon feeding. Although highly proliferative FSCs generally exhibit an extended lifespan, we find that constitutive Hh signaling drives FSC loss and premature sterility despite high proliferative rates. This occurs due to Hh-mediated induction of autophagy in FSCs via a Ptc-dependent, Smo-independent mechanism. Hh-dependent autophagy increases during aging, triggering FSC loss and consequent reproductive arrest. IIS is necessary and sufficient to suppress Hh-induced autophagy, promoting a stable proliferative state. These results suggest that opposing action of diet-responsive IIS and Hh signals determine reproductive lifespan by modulating the proliferation-autophagy balance in FSCs during aging.
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Affiliation(s)
- Tanu Singh
- Department of Molecular Therapeutics, Fox Chase Cancer Center, 333 Cottman Avenue, Philadelphia, PA 19111, USA; Department of Biochemistry and Molecular Biology, Drexel University College of Medicine, Philadelphia, PA 19111, USA
| | - Eric H Lee
- Department of Molecular Therapeutics, Fox Chase Cancer Center, 333 Cottman Avenue, Philadelphia, PA 19111, USA
| | - Tiffiney R Hartman
- Department of Molecular Therapeutics, Fox Chase Cancer Center, 333 Cottman Avenue, Philadelphia, PA 19111, USA
| | - Dara M Ruiz-Whalen
- Department of Molecular Therapeutics, Fox Chase Cancer Center, 333 Cottman Avenue, Philadelphia, PA 19111, USA
| | - Alana M O'Reilly
- Department of Molecular Therapeutics, Fox Chase Cancer Center, 333 Cottman Avenue, Philadelphia, PA 19111, USA.
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36
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Wingless/Wnt Signaling in Intestinal Development, Homeostasis, Regeneration and Tumorigenesis: A Drosophila Perspective. J Dev Biol 2018; 6:jdb6020008. [PMID: 29615557 PMCID: PMC6026893 DOI: 10.3390/jdb6020008] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2018] [Revised: 03/23/2018] [Accepted: 03/24/2018] [Indexed: 02/06/2023] Open
Abstract
In mammals, the Wnt/β-catenin signal transduction pathway regulates intestinal stem cell maintenance and proliferation, whereas Wnt pathway hyperactivation, resulting primarily from the inactivation of the tumor suppressor Adenomatous polyposis coli (APC), triggers the development of the vast majority of colorectal cancers. The Drosophila adult gut has recently emerged as a powerful model to elucidate the mechanisms by which Wingless/Wnt signaling regulates intestinal development, homeostasis, regeneration, and tumorigenesis. Herein, we review recent insights on the roles of Wnt signaling in Drosophila intestinal physiology and pathology.
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37
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Division-independent differentiation mandates proliferative competition among stem cells. Proc Natl Acad Sci U S A 2018; 115:E3182-E3191. [PMID: 29555768 DOI: 10.1073/pnas.1718646115] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Cancer-initiating gatekeeper mutations that arise in stem cells would be especially potent if they stabilize and expand an affected stem cell lineage. It is therefore important to understand how different stem cell organization strategies promote or prevent variant stem cell amplification in response to different types of mutation, including those that activate proliferation. Stem cell numbers can be maintained constant while producing differentiated products through individually asymmetrical division outcomes or by population asymmetry strategies in which individual stem cell lineages necessarily compete for niche space. We considered alternative mechanisms underlying population asymmetry and used quantitative modeling to predict starkly different consequences of altering proliferation rate: A variant, faster proliferating mutant stem cell should compete better only when stem cell division and differentiation are independent processes. For most types of stem cells, it has not been possible to ascertain experimentally whether division and differentiation are coupled. However, Drosophila follicle stem cells (FSCs) provided a favorable system with which to investigate population asymmetry mechanisms and also for measuring the impact of altered proliferation on competition. We found from detailed cell lineage studies that division and differentiation of an individual FSC are not coupled. We also found that FSC representation, reflecting maintenance and amplification, was highly responsive to genetic changes that altered only the rate of FSC proliferation. The FSC paradigm therefore provides definitive experimental evidence for the general principle that relative proliferation rate will always be a major determinant of competition among stem cells specifically when stem cell division and differentiation are independent.
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38
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Abstract
Unlike adult Drosophila ovaries, pupal ovaries are relatively difficult to access and examine due to their small size, translucence, and encasing within a pupal case. The challenge of dissecting pupal ovaries also lies in their physical location within the pupa: the ovaries are surrounded by fat body cells inside the pupal abdomen, and these fat cells must be removed to allow for proper antibody staining. To overcome these challenges, this protocol utilizes customized Pasteur pipets to extract fat body cells from the pupal abdomen. Moreover, a chambered coverglass is used in place of a microcentrifuge tube during the staining process to improve visibility of the pupae. However, despite these and other advantages of the tools used in this protocol, successful execution of these techniques may still involve several days of practice due to the small size of pupal ovaries. The techniques outlined in this protocol could be applied to time course experiments in which ovaries are analyzed at various stages of pupal development.
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Affiliation(s)
| | - Dorothea Godt
- Department of Cell and Systems Biology, University of Toronto
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39
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Waghmare I, Page-McCaw A. Wnt Signaling in Stem Cell Maintenance and Differentiation in the Drosophila Germarium. Genes (Basel) 2018; 9:genes9030127. [PMID: 29495453 PMCID: PMC5867848 DOI: 10.3390/genes9030127] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2018] [Revised: 02/13/2018] [Accepted: 02/14/2018] [Indexed: 01/19/2023] Open
Abstract
Wnt signaling is a conserved regulator of stem cell behaviors, and the Drosophila germarium has been an important model tissue for the study of stem cell maintenance, differentiation, and proliferation. Here we review Wnt signaling in the germarium, which houses two distinct types of ovarian stem cells: the anteriorly located germline stem cells (GSCs), which give rise to oocytes; and the mid-posteriorly located follicle stem cells (FSCs), which give rise to the somatic follicle cells that cover a developing oocyte. The maintenance and proliferation of GSCs and FSCs is regulated by the stem cell niches, whereas differentiation of the germline is regulated by the differentiation niche. Four distinct Wnt ligands are localized in the germarium, and we focus review on how these Wnt ligands and Wnt signaling affects maintenance and differentiation of both germline and follicle stem cells in their respective niches.
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Affiliation(s)
- Indrayani Waghmare
- Department of Cell and Developmental Biology and Program in Developmental Biology, Vanderbilt University School of Medicine, Nashville, TN 37240, USA.
| | - Andrea Page-McCaw
- Department of Cell and Developmental Biology and Program in Developmental Biology, Vanderbilt University School of Medicine, Nashville, TN 37240, USA.
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40
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Wang X, Page-McCaw A. Wnt6 maintains anterior escort cells as an integral component of the germline stem cell niche. Development 2018; 145:dev.158527. [PMID: 29361569 PMCID: PMC5818006 DOI: 10.1242/dev.158527] [Citation(s) in RCA: 46] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2017] [Accepted: 12/22/2017] [Indexed: 12/27/2022]
Abstract
Stem cells reside in a niche, a local environment whose cellular and molecular complexity is still being elucidated. In Drosophila ovaries, germline stem cells depend on cap cells for self-renewing signals and physical attachment. Germline stem cells also contact the anterior escort cells, and here we report that anterior escort cells are absolutely required for germline stem cell maintenance. When escort cells die from impaired Wnt signaling or hid expression, the loss of anterior escort cells causes loss of germline stem cells. Anterior escort cells function as an integral niche component by promoting DE-cadherin anchorage and by transiently expressing the Dpp ligand to promote full-strength BMP signaling in germline stem cells. Anterior escort cells are maintained by Wnt6 ligands produced by cap cells; without Wnt6 signaling, anterior escort cells die leaving vacancies in the niche, leading to loss of germline stem cells. Our data identify anterior escort cells as constituents of the germline stem cell niche, maintained by a cap cell-produced Wnt6 survival signal.
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Affiliation(s)
- Xiaoxi Wang
- Department of Cell and Developmental Biology and Program in Developmental Biology, Vanderbilt University School of Medicine, Nashville, TN 37240, USA
| | - Andrea Page-McCaw
- Department of Cell and Developmental Biology and Program in Developmental Biology, Vanderbilt University School of Medicine, Nashville, TN 37240, USA
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41
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Upadhyay M, Kuna M, Tudor S, Martino Cortez Y, Rangan P. A switch in the mode of Wnt signaling orchestrates the formation of germline stem cell differentiation niche in Drosophila. PLoS Genet 2018; 14:e1007154. [PMID: 29370168 PMCID: PMC5811049 DOI: 10.1371/journal.pgen.1007154] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2017] [Revised: 02/13/2018] [Accepted: 12/13/2017] [Indexed: 01/12/2023] Open
Abstract
Germline stem cell (GSC) self-renewal and differentiation into gametes is regulated by both intrinsic factors in the germ line as well as extrinsic factors from the surrounding somatic niche. dWnt4, in the escort cells of the adult somatic niche promotes GSC differentiation using the canonical β-catenin-dependent transcriptional pathway to regulate escort cell survival, adhesion to the germ line and downregulation of self-renewal signaling. Here, we show that in addition to the β-catenin-dependent canonical pathway, dWnt4 also uses downstream components of the Wnt non-canonical pathway to promote escort cell function earlier in development. We find that the downstream non-canonical components, RhoA, Rac1 and cdc42, are expressed at high levels and are active in escort cell precursors of the female larval gonad compared to the adult somatic niche. Consistent with this expression pattern, we find that the non-canonical pathway components function in the larval stages but not in adults to regulate GSC differentiation. In the larval gonad, dWnt4, RhoA, Rac1 and cdc42 are required to promote intermingling of escort cell precursors, a function that then promotes proper escort cell function in the adults. We find that dWnt4 acts by modulating the activity of RhoA, Rac1 and cdc42, but not their protein levels. Together, our results indicate that at different points of development, dWnt4 switches from using the non-canonical pathway components to using a β-catenin-dependent canonical pathway in the escort cells to facilitate the proper differentiation of GSCs. Germ line association with the somatic cells is critical for various aspects of germ cell biology, including migration, self-renewal and differentiation. In Drosophila females, soma–germ line association begins during embryogenesis and continues until the mature egg is formed. In the adult, the somatic escort cells promote differentiation of the germline stem cell daughter using Wnt signaling. dWnt4, a Wnt ligand, acts in an autocrine manner in these escort cells, using the canonical pathway to regulate survival, division and encapsulation of the stem cell daughter, a function critical for differentiation. Here, we show at an earlier stage, in the larvae, the same ligand uses components of Wnt non-canonical pathway, RhoA, Rac1 and cdc42, to regulate proper mingling of escort cell precursors between the germ cells. Thus, dWnt4 uses different modules of signaling at different points in development to promote cell movement and control cytoplasmic protrusions. As Wnts have been associated with cancers, understanding how Wnts modulate cell movement by switching on and off different modules may lead to insights into the etiology and progression of cancers.
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Affiliation(s)
- Maitreyi Upadhyay
- Department of Biological Sciences/RNA Institute, University at Albany SUNY, Albany, New York, United States of America
| | - Michael Kuna
- Department of Biological Sciences/RNA Institute, University at Albany SUNY, Albany, New York, United States of America
- Albany Medical College, Albany, New York, United States of America
| | - Sara Tudor
- Department of Biological Sciences/RNA Institute, University at Albany SUNY, Albany, New York, United States of America
- Albany Medical College, Albany, New York, United States of America
| | - Yesenia Martino Cortez
- Department of Biological Sciences/RNA Institute, University at Albany SUNY, Albany, New York, United States of America
- Tufts University School of Medicine, Boston, Massachusetts, United States of America
| | - Prashanth Rangan
- Department of Biological Sciences/RNA Institute, University at Albany SUNY, Albany, New York, United States of America
- * E-mail:
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42
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Carroll TD, Langlands AJ, Osborne JM, Newton IP, Appleton PL, Näthke I. Interkinetic nuclear migration and basal tethering facilitates post-mitotic daughter separation in intestinal organoids. J Cell Sci 2017; 130:3862-3877. [PMID: 28982714 PMCID: PMC5702049 DOI: 10.1242/jcs.211656] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2017] [Accepted: 10/02/2017] [Indexed: 01/08/2023] Open
Abstract
Homeostasis of renewing tissues requires balanced proliferation, differentiation and movement. This is particularly important in the intestinal epithelium where lineage tracing suggests that stochastic differentiation choices are intricately coupled to the position of a cell relative to a niche. To determine how position is achieved, we followed proliferating cells in intestinal organoids and discovered that the behaviour of mitotic sisters predicted long-term positioning. We found that, normally, 70% of sisters remain neighbours, while 30% lose contact and separate after cytokinesis. These post-mitotic placements predict longer term differences in positions assumed by sisters: adjacent sisters reach similar positions over time; in a pair of separating sisters, one remains close to its birthplace while the other is displaced upward. Computationally modelling crypt dynamics confirmed that post-mitotic separation leads to sisters reaching different compartments. We show that interkinetic nuclear migration, cell size and asymmetric tethering by a process extending from the basal side of cells contribute to separations. These processes are altered in adenomatous polyposis coli (Apc) mutant epithelia where separation is lost. We conclude that post-mitotic placement contributes to stochastic niche exit and, when defective, supports the clonal expansion of Apc mutant cells.
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Affiliation(s)
- Thomas D. Carroll
- Cell & Developmental Biology, University of Dundee, Dundee DD1 5EH, UK
| | | | - James M. Osborne
- School of Mathematics and Statistics, University of Melbourne, Melbourne 3010, Australia
| | - Ian P. Newton
- Cell & Developmental Biology, University of Dundee, Dundee DD1 5EH, UK
| | - Paul L. Appleton
- Dundee Imaging Facility, University of Dundee, Dundee DD1 5EH, UK
| | - Inke Näthke
- Cell & Developmental Biology, University of Dundee, Dundee DD1 5EH, UK
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43
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Dai W, Peterson A, Kenney T, Burrous H, Montell DJ. Quantitative microscopy of the Drosophila ovary shows multiple niche signals specify progenitor cell fate. Nat Commun 2017; 8:1244. [PMID: 29093440 PMCID: PMC5665863 DOI: 10.1038/s41467-017-01322-9] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2016] [Accepted: 09/09/2017] [Indexed: 01/28/2023] Open
Abstract
Adult stem cells commonly give rise to transit-amplifying progenitors, whose progeny differentiate into distinct cell types. It is unclear if stem cell niche signals coordinate fate decisions within the progenitor pool. Here we use quantitative analysis of Wnt, Hh, and Notch signalling reporters and the cell fate markers Eyes Absent (Eya) and Castor (Cas) to study the effects of hyper-activation and loss of niche signals on progenitor development in the Drosophila ovary. Follicle stem cell (FSC) progeny adopt distinct polar, stalk, and main body cell fates. We show that Wnt signalling transiently inhibits expression of the main body cell fate determinant Eya, and Wnt hyperactivity strongly biases cells towards polar and stalk fates. Hh signalling independently controls the proliferation to differentiation transition. Notch is permissive but not instructive for differentiation of multiple cell types. These findings reveal that multiple niche signals coordinate cell fates and differentiation of progenitor cells.
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Affiliation(s)
- Wei Dai
- MCDB Department, University of California, Santa Barbara, CA, 93106, USA
| | - Amy Peterson
- MCDB Department, University of California, Santa Barbara, CA, 93106, USA
| | - Thomas Kenney
- MCDB Department, University of California, Santa Barbara, CA, 93106, USA
| | - Haley Burrous
- MCDB Department, University of California, Santa Barbara, CA, 93106, USA
| | - Denise J Montell
- MCDB Department, University of California, Santa Barbara, CA, 93106, USA.
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44
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Huang J, Reilein A, Kalderon D. Yorkie and Hedgehog independently restrict BMP production in escort cells to permit germline differentiation in the Drosophila ovary. Development 2017; 144:2584-2594. [PMID: 28619819 DOI: 10.1242/dev.147702] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2016] [Accepted: 06/08/2017] [Indexed: 12/13/2022]
Abstract
Multiple signaling pathways guide the behavior and differentiation of both germline stem cells (GSCs) and somatic follicle stem cells (FSCs) in the Drosophila germarium, necessitating careful control of signal generation, range and responses. Signal integration involves escort cells (ECs), which promote differentiation of the GSC derivatives they envelop, provide niche signals for FSCs and derive directly from FSCs in adults. Hedgehog (Hh) signaling induces the Hippo pathway effector Yorkie (Yki) to promote proliferation and maintenance of FSCs, but Hh also signals to ECs, which are quiescent. Here, we show that in ECs both Hh and Yki limit production of BMP ligands to allow germline differentiation. Loss of Yki produced a more severe germarial phenotype than loss of Hh signaling and principally induced a different BMP ligand. Moreover, Yki activity reporters and epistasis tests showed that Yki does not mediate the key actions of Hh signaling in ECs. Thus, both the coupling and output of the Hh and Yki signaling pathways differ between FSCs and ECs despite their proximity and the fact that FSCs give rise directly to ECs.
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Affiliation(s)
- Jianhua Huang
- State Key Laboratory of Rice Biology, Institute of Insect Sciences, Zhejiang University, Hangzhou, 310058, China.,Department of Biological Sciences, Columbia University, 1212 Amsterdam Ave., New York, NY 10027, USA
| | - Amy Reilein
- Department of Biological Sciences, Columbia University, 1212 Amsterdam Ave., New York, NY 10027, USA
| | - Daniel Kalderon
- Department of Biological Sciences, Columbia University, 1212 Amsterdam Ave., New York, NY 10027, USA
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