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Ranjan R, Ma B, Gleason RJ, Liao Y, Bi Y, Davis BEM, Yang G, Clark M, Mahajan V, Condon M, Broderick NA, Chen X. Modulating DNA Polα Enhances Cell Reprogramming Across Species. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.09.19.613993. [PMID: 39345551 PMCID: PMC11429986 DOI: 10.1101/2024.09.19.613993] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/01/2024]
Abstract
As a fundamental biological process, DNA replication ensures the accurate copying of genetic information. However, the impact of this process on cellular plasticity in multicellular organisms remains elusive. Here, we find that reducing the level or activity of a replication component, DNA Polymerase α (Polα), facilitates cell reprogramming in diverse stem cell systems across species. In Drosophila male and female germline stem cell lineages, reducing Polα levels using heterozygotes significantly enhances fertility of both sexes, promoting reproductivity during aging without compromising their longevity. Consistently, in C. elegans the pola heterozygous hermaphrodites exhibit increased fertility without a reduction in lifespan, suggesting that this phenomenon is conserved. Moreover, in male germline and female intestinal stem cell lineages of Drosophila, polα heterozygotes exhibit increased resistance to tissue damage caused by genetic ablation or pathogen infection, leading to enhanced regeneration and improved survival during post-injury recovery, respectively. Additionally, fine tuning of an inhibitor to modulate Polα activity significantly enhances the efficiency of reprogramming human embryonic fibroblasts into induced pluripotent cells. Together, these findings unveil novel roles of a DNA replication component in regulating cellular reprogramming potential, and thus hold promise for promoting tissue health, facilitating post-injury rehabilitation, and enhancing healthspan.
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Affiliation(s)
- Rajesh Ranjan
- Department of Biology, The Johns Hopkins University, Baltimore, MD 21218, USA
- Howard Hughes Medical Institute, Department of Biology, The Johns Hopkins University, 3400 North Charles Street, Baltimore, Baltimore, MD 21218, USA
| | - Binbin Ma
- Department of Biology, The Johns Hopkins University, Baltimore, MD 21218, USA
- Howard Hughes Medical Institute, Department of Biology, The Johns Hopkins University, 3400 North Charles Street, Baltimore, Baltimore, MD 21218, USA
| | - Ryan J. Gleason
- Department of Biology, The Johns Hopkins University, Baltimore, MD 21218, USA
| | - Yijun Liao
- Department of Biology, The Johns Hopkins University, Baltimore, MD 21218, USA
| | - Yingshan Bi
- Department of Biology, The Johns Hopkins University, Baltimore, MD 21218, USA
| | - Brendon E. M. Davis
- Department of Biology, The Johns Hopkins University, Baltimore, MD 21218, USA
| | - Guanghui Yang
- Department of Biology, The Johns Hopkins University, Baltimore, MD 21218, USA
- Howard Hughes Medical Institute, Department of Biology, The Johns Hopkins University, 3400 North Charles Street, Baltimore, Baltimore, MD 21218, USA
| | - Maggie Clark
- Department of Biology, The Johns Hopkins University, Baltimore, MD 21218, USA
| | - Vikrant Mahajan
- Department of Biology, The Johns Hopkins University, Baltimore, MD 21218, USA
| | - Madison Condon
- Department of Biology, The Johns Hopkins University, Baltimore, MD 21218, USA
| | | | - Xin Chen
- Department of Biology, The Johns Hopkins University, Baltimore, MD 21218, USA
- Howard Hughes Medical Institute, Department of Biology, The Johns Hopkins University, 3400 North Charles Street, Baltimore, Baltimore, MD 21218, USA
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Wang M, Chen X, Wu Y, Zheng Q, Chen W, Yan Y, Luan X, Shen C, Fang J, Zheng B, Yu J. RpS13 controls the homeostasis of germline stem cell niche through Rho1-mediated signals in the Drosophila testis. Cell Prolif 2020; 53:e12899. [PMID: 32896929 PMCID: PMC7574871 DOI: 10.1111/cpr.12899] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2020] [Revised: 08/15/2020] [Accepted: 08/18/2020] [Indexed: 12/20/2022] Open
Abstract
Objectives Stem cell niche regulated the renewal and differentiation of germline stem cells (GSCs) in Drosophila. Previously, we and others identified a series of genes encoding ribosomal proteins that may contribute to the self‐renewal and differentiation of GSCs. However, the mechanisms that maintain and differentiate GSCs in their niches were not well understood. Materials and Methods Flies were used to generate tissue‐specific gene knockdown. Small interfering RNAs were used to knockdown genes in S2 cells. qRT‐PCR was used to examine the relative mRNA expression level. TUNEL staining or flow cytometry assays were used to detect cell survival. Immunofluorescence was used to determine protein localization and expression pattern. Results Herein, using a genetic manipulation approach, we investigated the role of ribosomal protein S13 (RpS13) in testes and S2 cells. We reported that RpS13 was required for the self‐renewal and differentiation of GSCs. We also demonstrated that RpS13 regulated cell proliferation and apoptosis. Mechanistically, we showed that RpS13 regulated the expression of ribosome subunits and could moderate the expression of the Rho1, DE‐cad and Arm proteins. Notably, Rho1 imitated the phenotype of RpS13 in both Drosophila testes and S2 cells, and recruited cell adhesions, which was mediated by the DE‐cad and Arm proteins. Conclusion These findings uncover a novel mechanism of RpS13 that mediates Rho1 signals in the stem cell niche of the Drosophila testis.
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Affiliation(s)
- Min Wang
- Department of Gynecology, the Affiliated Hospital of Jiangsu University, Jiangsu University, Zhenjiang, China
| | - Xia Chen
- Department of Gynecology, the Affiliated Hospital of Jiangsu University, Jiangsu University, Zhenjiang, China
| | - Yibo Wu
- Human Reproductive and Genetic Center, Affiliated Hospital of Jiangnan University, Wuxi, Jiangsu, China
| | - Qianwen Zheng
- Department of Gynecology, the Affiliated Hospital of Jiangsu University, Jiangsu University, Zhenjiang, China
| | - Wanyin Chen
- Department of Gynecology, the Affiliated Hospital of Jiangsu University, Jiangsu University, Zhenjiang, China
| | - Yidan Yan
- Department of Gynecology, the Affiliated Hospital of Jiangsu University, Jiangsu University, Zhenjiang, China
| | - Xiaojin Luan
- Department of Gynecology, the Affiliated Hospital of Jiangsu University, Jiangsu University, Zhenjiang, China
| | - Cong Shen
- State Key Laboratory of Reproductive Medicine, Center for Reproduction and Genetics, Suzhou Municipal Hospital, the Affiliated Suzhou Hospital of Nanjing Medical University, Suzhou, China
| | - Jie Fang
- Department of Gynecology, the Affiliated Hospital of Jiangsu University, Jiangsu University, Zhenjiang, China
| | - Bo Zheng
- State Key Laboratory of Reproductive Medicine, Center for Reproduction and Genetics, Suzhou Municipal Hospital, the Affiliated Suzhou Hospital of Nanjing Medical University, Suzhou, China
| | - Jun Yu
- Department of Gynecology, the Affiliated Hospital of Jiangsu University, Jiangsu University, Zhenjiang, China
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Shi Z, Lim C, Tran V, Cui K, Zhao K, Chen X. Single-cyst transcriptome analysis of Drosophila male germline stem cell lineage. Development 2020; 147:dev.184259. [PMID: 32122991 DOI: 10.1242/dev.184259] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2019] [Accepted: 02/23/2020] [Indexed: 12/31/2022]
Abstract
The Drosophila male germline stem cell (GSC) lineage provides a great model to understand stem cell maintenance, proliferation, differentiation and dedifferentiation. Here, we use the Drosophila GSC lineage to systematically analyze the transcriptome of discrete but continuously differentiating germline cysts. We first isolated single cysts at each recognizable stage from wild-type testes, which were subsequently applied for RNA-seq analyses. Our data delineate a high-resolution transcriptome atlas in the entire male GSC lineage: the most dramatic switch occurs from early to late spermatocyte, followed by the change from the mitotic spermatogonia to early meiotic spermatocyte. By contrast, the transit-amplifying spermatogonia cysts display similar transcriptomes, suggesting common molecular features among these stages, which may underlie their similar behavior during both differentiation and dedifferentiation processes. Finally, distinct differentiating germ cell cyst samples do not exhibit obvious dosage compensation of X-chromosomal genes, even considering the paucity of X-chromosomal gene expression during meiosis, which is different from somatic cells. Together, our single cyst-resolution, genome-wide transcriptional profile analyses provide an unprecedented resource to understand many questions in both germ cell biology and stem cell biology fields.
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Affiliation(s)
- Zhen Shi
- Department of Biology, The Johns Hopkins University, 3400 North Charles Street, Baltimore, MD 21218, USA
| | - Cindy Lim
- Department of Biology, The Johns Hopkins University, 3400 North Charles Street, Baltimore, MD 21218, USA
| | - Vuong Tran
- Department of Biology, The Johns Hopkins University, 3400 North Charles Street, Baltimore, MD 21218, USA
| | - Kairong Cui
- Systems Biology Center (SBC), Division of Intramural Research (DIR), National Heart, Lung and Blood Institute, National Institutes of Health, 10 Center Drive, MSC 1674, Building 10, Room 7B05, Bethesda, MD 20892, USA
| | - Keji Zhao
- Systems Biology Center (SBC), Division of Intramural Research (DIR), National Heart, Lung and Blood Institute, National Institutes of Health, 10 Center Drive, MSC 1674, Building 10, Room 7B05, Bethesda, MD 20892, USA
| | - Xin Chen
- Department of Biology, The Johns Hopkins University, 3400 North Charles Street, Baltimore, MD 21218, USA
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Eun SH, Feng L, Cedeno-Rosario L, Gan Q, Wei G, Cui K, Zhao K, Chen X. Polycomb Group Gene E(z) Is Required for Spermatogonial Dedifferentiation in Drosophila Adult Testis. J Mol Biol 2017; 429:2030-2041. [PMID: 28434938 PMCID: PMC5516936 DOI: 10.1016/j.jmb.2017.04.012] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2017] [Revised: 03/30/2017] [Accepted: 04/17/2017] [Indexed: 12/12/2022]
Abstract
Dedifferentiation is an important process to replenish lost stem cells during aging or regeneration after injury to maintain tissue homeostasis. Here, we report that Enhancer of Zeste [E(z)], a component of the Polycomb repression complex 2 (PRC2), is required to maintain a stable pool of germline stem cells (GSCs) within the niche microenvironment. During aging, germ cells with reduced E(z) activity cannot meet that requirement, but the defect arises from neither increased GSC death nor premature differentiation. Instead, we found evidence that the decrease of GSCs upon the inactivation of E(z) in the germline could be attributed to defective dedifferentiation. During recovery from genetically manipulated GSC depletion, E(z) knockdown germ cells also fail to replenish lost GSCs. Taken together, our data suggest that E(z) acts intrinsically in germ cells to activate dedifferentiation and thus replenish lost GSCs during both aging and tissue regeneration.
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Affiliation(s)
- Suk Ho Eun
- Department of Biology, The Johns Hopkins University, Baltimore, MD 21218, USA
| | - Lijuan Feng
- Department of Biology, The Johns Hopkins University, Baltimore, MD 21218, USA
| | - Luis Cedeno-Rosario
- Department of Biology, The Johns Hopkins University, Baltimore, MD 21218, USA
| | - Qiang Gan
- Department of Biology, The Johns Hopkins University, Baltimore, MD 21218, USA
| | - Gang Wei
- Laboratory of Molecular Immunology, National Heart, Lung and Blood Institute, NIH, Bethesda, MD 20892, USA
| | - Kairong Cui
- Laboratory of Molecular Immunology, National Heart, Lung and Blood Institute, NIH, Bethesda, MD 20892, USA
| | - Keji Zhao
- Laboratory of Molecular Immunology, National Heart, Lung and Blood Institute, NIH, Bethesda, MD 20892, USA
| | - Xin Chen
- Department of Biology, The Johns Hopkins University, Baltimore, MD 21218, USA.
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5
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Li GL, Qian H. Transcriptome using Illumina sequencing reveals the traits of spermatogenesis and developing testes in Eriocheir sinensis. PLoS One 2017; 12:e0172478. [PMID: 28212420 PMCID: PMC5315355 DOI: 10.1371/journal.pone.0172478] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2016] [Accepted: 02/05/2017] [Indexed: 11/19/2022] Open
Abstract
Chinese mitten crab (Eriocheir sinensis) has the spermatozoa with typical aflagellate, decondensed chromatin, cup-shaped nuclei, and radial arms. However, the mechanism of spermatogenesis during which the specific spermatozoa are generated in this species is yet unclear. Here, the transcriptome of developing testis in E. sinensis was analyzed using the ways of RNA-seq and bioinformatics analysis to identify candidate genes potentially involved in development of testis and spermatogenesis. The Illumina HiSeq2500 sequencing of three replicons of samples produced a total of 145.19 M clean reads representing with a total of 21.34 Gb bases and 45.48% GC content. 56.30% clean reads were mapped to the draft genome of E. sinensis. The assembly of the transcriptome yielded contigs of 5691802 sequences and unigenes of 406527 sequences. Total 24246 and 40793 transcripts were annotated using Swissprot and Nr database, respectively. There were 48213 (70.31%) and 7858 (46.25%) transcripts with identity of more than 99 matching to mature testis unigenes in the databases of Nr and EST, respectively. The analytic results of KOG, GO and KEGG showed wide potential molecular functions of transcripts in the developing testes. KEGG analysis of unigenes yielded total 9422 predicted genes. Those predicted genes were involved in total 216 KEGG pathways related to the physiological activities of developing testis. 1975 predicted genes were involved in cellular and subcellular structural alteration of male germ cells. There were important roles of some pathways in the processes of morphological and structural biogenesis pertaining to testis development and spermatogenesis. Other 583 unigenes encoding the genetic and epigenetic factors also be found, which might contribute to the decondensation and stability of decondensed nuclei in the spermatozoa. These predicted events provide a view of the potential molecular mechanisms of development of testis and spermatogenesis in E. sinensis.
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Affiliation(s)
- Gen-Liang Li
- Youjiang Medical University for Nationalities, Baise, Guangxi, China
| | - Hui Qian
- Youjiang Medical University for Nationalities, Baise, Guangxi, China
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6
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Lim C, Gandhi S, Biniossek ML, Feng L, Schilling O, Urban S, Chen X. An Aminopeptidase in the Drosophila Testicular Niche Acts in Germline Stem Cell Maintenance and Spermatogonial Dedifferentiation. Cell Rep 2015; 13:315-25. [PMID: 26440886 DOI: 10.1016/j.celrep.2015.09.001] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2014] [Revised: 06/25/2015] [Accepted: 08/31/2015] [Indexed: 12/27/2022] Open
Abstract
Extrinsic cues from the niche are known to regulate adult stem cell self-renewal versus differentiation. Here, we report that an aminopeptidase Slamdance (Sda) acts in the Drosophila testicular niche to maintain germline stem cells (GSCs) and regulate progenitor germ cell dedifferentiation. Mutations in sda lead to dramatic testicular niche deterioration and stem cell loss. Recombinant Sda has specific aminopeptidase activity in vitro, and the in vivo function of Sda requires an intact aminopeptidase domain. Sda is required for accumulation of mature DE-cadherin, and overexpression of DE-cadherin rescues most sda mutant phenotypes, suggesting that DE-cadherin is an important target of Sda. Finally, Sda is both necessary and sufficient to promote dedifferentiation during aging and recovery from genetically manipulated depletion of GSCs. Together, our results suggest that a niche factor promotes both stem cell maintenance and progenitor cell dedifferentiation.
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Affiliation(s)
- Cindy Lim
- Department of Biology, The Johns Hopkins University, Baltimore, MD 21218, USA
| | - Shiv Gandhi
- Howard Hughes Medical Institute, Department of Molecular Biology and Genetics, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Martin L Biniossek
- Institute of Molecular Medicine and Cell Research, University of Freiburg, 79104 Freiburg, Germany
| | - Lijuan Feng
- Department of Biology, The Johns Hopkins University, Baltimore, MD 21218, USA
| | - Oliver Schilling
- Institute of Molecular Medicine and Cell Research and BIOSS Centre for Biological Signaling Studies, University of Freiburg, 79104 Freiburg, Germany
| | - Siniša Urban
- Howard Hughes Medical Institute, Department of Molecular Biology and Genetics, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Xin Chen
- Department of Biology, The Johns Hopkins University, Baltimore, MD 21218, USA.
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7
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Lim C, Tarayrah L, Chen X. Transcriptional regulation during Drosophila spermatogenesis. SPERMATOGENESIS 2014; 2:158-166. [PMID: 23087835 PMCID: PMC3469439 DOI: 10.4161/spmg.21775] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Drosophila spermatogenesis has become a paradigmatic system for the study of mechanisms that regulate adult stem cell maintenance, proliferation and differentiation. The dramatic cellular differentiation process from germline stem cell (GSC) to mature sperm is accompanied by dynamic changes in gene expression, which are regulated at transcriptional, post-transcriptional (including translational) and post-translational levels. Post-transcriptional regulation has been proposed as a unique feature of germ cells. However, recent studies have provided new insights into transcriptional regulation during Drosophila spermatogenesis. Both signaling pathways and epigenetic mechanisms act to orchestrate the transcriptional regulation of distinct genes at different germ cell differentiation stages. Many of the regulatory pathways that control male gamete differentiation in Drosophila are conserved in mammals. Therefore, studies using Drosophila spermatogenesis will provide insight into the molecular mechanisms that regulate mammalian germ cell differentiation pathways.
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Affiliation(s)
- Cindy Lim
- Department of Biology; The Johns Hopkins University; Baltimore, MD USA
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8
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Demarco RS, Eikenes ÅH, Haglund K, Jones DL. Investigating spermatogenesis in Drosophila melanogaster. Methods 2014; 68:218-27. [PMID: 24798812 DOI: 10.1016/j.ymeth.2014.04.020] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2014] [Revised: 04/24/2014] [Accepted: 04/25/2014] [Indexed: 01/05/2023] Open
Abstract
The process of spermatogenesis in Drosophila melanogaster provides a powerful model system to probe a variety of developmental and cell biological questions, such as the characterization of mechanisms that regulate stem cell behavior, cytokinesis, meiosis, and mitochondrial dynamics. Classical genetic approaches, together with binary expression systems, FRT-mediated recombination, and novel imaging systems to capture single cell behavior, are rapidly expanding our knowledge of the molecular mechanisms regulating all aspects of spermatogenesis. This methods chapter provides a detailed description of the system, a review of key questions that have been addressed or remain unanswered thus far, and an introduction to tools and techniques available to probe each stage of spermatogenesis.
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Affiliation(s)
- Rafael S Demarco
- Department of Molecular, Cell and Developmental Biology, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Åsmund H Eikenes
- Department of Molecular, Cell and Developmental Biology, University of California, Los Angeles, Los Angeles, CA 90095, USA; Department of Biochemistry, Institute for Cancer Research, Oslo University Hospital, 0379 Montebello, Norway; Centre for Cancer Biomedicine, Faculty of Medicine, Oslo University Hospital, 0379 Montebello, Norway
| | - Kaisa Haglund
- Department of Biochemistry, Institute for Cancer Research, Oslo University Hospital, 0379 Montebello, Norway; Centre for Cancer Biomedicine, Faculty of Medicine, Oslo University Hospital, 0379 Montebello, Norway
| | - D Leanne Jones
- Department of Molecular, Cell and Developmental Biology, University of California, Los Angeles, Los Angeles, CA 90095, USA.
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9
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Voog J, Sandall SL, Hime GR, Resende LPF, Loza-Coll M, Aslanian A, Yates JR, Hunter T, Fuller MT, Jones DL. Escargot restricts niche cell to stem cell conversion in the Drosophila testis. Cell Rep 2014; 7:722-34. [PMID: 24794442 DOI: 10.1016/j.celrep.2014.04.025] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2012] [Revised: 02/05/2013] [Accepted: 04/17/2014] [Indexed: 01/08/2023] Open
Abstract
Stem cells reside within specialized microenvironments, or niches, that control many aspects of stem cell behavior. Somatic hub cells in the Drosophila testis regulate the behavior of cyst stem cells (CySCs) and germline stem cells (GSCs) and are a primary component of the testis stem cell niche. The shutoff (shof) mutation, characterized by premature loss of GSCs and CySCs, was mapped to a locus encoding the evolutionarily conserved transcription factor Escargot (Esg). Hub cells depleted of Esg acquire CySC characteristics and differentiate as cyst cells, resulting in complete loss of hub cells and eventually CySCs and GSCs, similar to the shof mutant phenotype. We identified Esg-interacting proteins and demonstrate an interaction between Esg and the corepressor C-terminal binding protein (CtBP), which was also required for maintenance of hub cell fate. Our results indicate that niche cells can acquire stem cell properties upon removal of a single transcription factor in vivo.
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Affiliation(s)
- Justin Voog
- Department of Biomedical Sciences, University of California, San Diego, La Jolla, CA, 92037, USA; Laboratory of Genetics, Salk Institute for Biological Studies, La Jolla, CA 92037, USA
| | - Sharsti L Sandall
- Laboratory of Genetics, Salk Institute for Biological Studies, La Jolla, CA 92037, USA
| | - Gary R Hime
- ARC Centre of Excellence in Biotechnology and Development, University of Melbourne, VIC 3010, Australia; Department of Anatomy and Neuroscience, University of Melbourne, VIC 3010, Australia
| | - Luís Pedro F Resende
- Laboratory of Genetics, Salk Institute for Biological Studies, La Jolla, CA 92037, USA; GABBA, Instituto Ciências Biomédicas Abel Salazar, University of Porto, Portugal
| | - Mariano Loza-Coll
- Laboratory of Genetics, Salk Institute for Biological Studies, La Jolla, CA 92037, USA; Department of Molecular, Cell, and Developmental Biology, University of California, Los Angeles, Los Angeles, CA, 90095, USA
| | - Aaron Aslanian
- Molecular and Cell Biology Laboratory, Salk Institute for Biological Studies, La Jolla, CA, 92037, USA
| | - John R Yates
- Department of Chemical Physiology, The Scripps Research Institute, La Jolla, CA, 92037, USA
| | - Tony Hunter
- Molecular and Cell Biology Laboratory, Salk Institute for Biological Studies, La Jolla, CA, 92037, USA
| | - Margaret T Fuller
- Department of Developmental Biology, Stanford University School of Medicine, Stanford, CA, 94305, USA; Department of Genetics, Stanford University School of Medicine, Stanford, CA, 94305, USA
| | - D Leanne Jones
- Laboratory of Genetics, Salk Institute for Biological Studies, La Jolla, CA 92037, USA; Department of Molecular, Cell, and Developmental Biology, University of California, Los Angeles, Los Angeles, CA, 90095, USA.
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A temporal signature of epidermal growth factor signaling regulates the differentiation of germline cells in testes of Drosophila melanogaster. PLoS One 2013; 8:e70678. [PMID: 23940622 PMCID: PMC3734272 DOI: 10.1371/journal.pone.0070678] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2013] [Accepted: 06/21/2013] [Indexed: 01/08/2023] Open
Abstract
Tissue replenishment from stem cells follows a precise cascade of events, during which stem cell daughters first proliferate by mitotic transit amplifying divisions and then enter terminal differentiation. Here we address how stem cell daughters are guided through the early steps of development. In Drosophila testes, somatic cyst cells enclose the proliferating and differentiating germline cells and the units of germline and surrounding cyst cells are commonly referred to as cysts. By characterizing flies with reduced or increased Epidermal Growth Factor (EGF) signaling we show that EGF triggers different responses in the cysts dependent on its dose. In addition to the previously reported requirement for EGF signaling in cyst formation, a low dose of EGF signaling is required for the progression of the germline cells through transit amplifying divisions, and a high dose of EGF signaling promotes terminal differentiation. Terminal differentiation was promoted in testes expressing a constitutively active EGF Receptor (EGFR) and in testes expressing both a secreted EGF and the EGFR in the cyst cells, but not in testes expressing either only EGF or only EGFR. We propose that as the cysts develop, a temporal signature of EGF signaling is created by the coordinated increase of both the production of active ligands by the germline cells and the amount of available receptor molecules on the cyst cells.
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Abstract
Germline stem cells are key to genome transmission to future generations. Over recent years, there have been numerous insights into the regulatory mechanisms that govern both germ cell specification and the maintenance of the germline in adults. Complex regulatory interactions with both the niche and the environment modulate germline stem cell function. This perspective highlights some examples of this regulation to illustrate the diversity and complexity of the mechanisms involved.
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Affiliation(s)
- Ruth Lehmann
- Howard Hughes Medical Institute; Skirball Institute, The Helen L. and Martin S. Kimmel Center for Stem Cell Biology, Department of Cell Biology, New York University School of Medicine, 540 First Avenue, New York, NY 10016, USA.
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12
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Abstract
In nature, individuals vary tremendously in condition and this may be an important source of variation in mutation rate. Condition is likely to affect cell state and thereby impact the amount of DNA damage sustained and/or the way it is repaired. Here, we focus on DNA repair. If low-condition individuals are less capable of devoting the same level of resources to accurate repair, they may suffer higher mutation rates. However, repair decisions are also governed by various aspects of cell physiology, which may render the prediction that "higher-condition individuals use better repair mechanisms" too simplistic. We use a larval diet manipulation in Drosophila melanogaster to create high- and low-condition individuals and then contrast their relative usage of three repair pathways [homologous recombination (HR), single-strand annealing (SSA), and nonhomologous end joining (NHEJ)] that differ in their mechanistic requirements and their mutational consequences. We find that low-condition flies are more likely than high-condition flies to use the most conservative of these three repair pathways, suggesting that physiological constraints on repair pathway usage may be more important than energetic costs. We also show that the repair differences between high- and low-condition flies resemble those between young and old flies, suggesting the underlying mechanisms may be similar. Finally, we observe that the effect of larval diet on adult repair increases as flies age, indicating that developmental differences early in life can have long-lasting consequences.
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Matunis EL, Stine RR, de Cuevas M. Recent advances in Drosophila male germline stem cell biology. SPERMATOGENESIS 2012; 2:137-144. [PMID: 23087833 PMCID: PMC3469437 DOI: 10.4161/spmg.21763] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The ability of stem cells to divide asymmetrically to produce both self-renewing and differentiating daughter cells sustains many adult tissues, but germline stem cells (GSCs) are unique among stem cells as they perpetuate the genome of the species. The cellular and molecular mechanisms regulating most mammalian stem cells in their endogenous local microenvironments, or niches, are quite challenging to study. However, studies of stem cell niches such as those found in the Drosophila gonads have proven very useful. In these tissues, GSCs are housed in a readily identifiable niche, and the ability to genetically manipulate these cells and their neighbors has uncovered several fundamental mechanisms that are relevant to stem cells more generally. Here, we summarize recent work on the regulation of GSCs in the Drosophila testis niche by intercellular signals, and on the intracellular mechanisms that cooperate with these signals to ensure the survival of the germline. This review focuses on GSCs within the adult Drosophila testis; somatic stem cells in this tissue are reviewed by Zoller and Schulz in this issue.(1) For a review of the testis niche as a whole, see de Cuevas and Matunis,(2) and for more comprehensive reviews of the Drosophila testis, refer to Fuller(3) and Davies and Fuller.(4).
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Affiliation(s)
- Erika L. Matunis
- Department of Cell Biology; Johns Hopkins University School of Medicine; Baltimore, MD USA
| | - Rachel R. Stine
- Department of Cell Biology; Johns Hopkins University School of Medicine; Baltimore, MD USA
| | - Margaret de Cuevas
- Department of Cell Biology; Johns Hopkins University School of Medicine; Baltimore, MD USA
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