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Belles X, Piulachs MD. Ecdysone signalling and ovarian development in insects: from stem cells to ovarian follicle formation. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2014; 1849:181-6. [PMID: 24939835 DOI: 10.1016/j.bbagrm.2014.05.025] [Citation(s) in RCA: 77] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/21/2014] [Revised: 05/19/2014] [Accepted: 05/28/2014] [Indexed: 12/19/2022]
Abstract
Although a great deal of information is available concerning the role of ecdysone in insect oogenesis, research has tended to focus on vitellogenesis and choriogenesis. As such, the study of oogenesis in a strict sense has received much less attention. This situation changed recently when a number of observations carried out in the meroistic polytrophic ovarioles of Drosophila melanogaster started to unravel the key roles played by ecdysone in different steps of oogenesis. Thus, in larval stages, a non-autonomous role of ecdysone, first in repression and later in activation, of stem cell niche and primordial germ cell differentiation has been reported. In the adult, ecdysone stimulates the proliferation of germline stem cells, plays a role in stem cell niche maintenance and is needed non-cell-autonomously for correct differentiation of germline stem cells. Moreover, in somatic cells ecdysone is required for 16-cell cyst formation and for ovarian follicle development. In the transition from stages 8 to 9 of oogenesis, ecdysone signalling is fundamental when deciding whether or not to go ahead with vitellogenesis depending on the nutritional status, as well as to start border cell migration. This article is part of a Special Issue entitled: Nuclear receptors in animal development.
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Affiliation(s)
- Xavier Belles
- Institut de Biologia Evolutiva (CSIC-Universitat Pompeu Fabra), Passeig Marítim de la Barceloneta 37, 08003 Barcelona, Spain.
| | - Maria-Dolors Piulachs
- Institut de Biologia Evolutiva (CSIC-Universitat Pompeu Fabra), Passeig Marítim de la Barceloneta 37, 08003 Barcelona, Spain
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102
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Goldstein J, Fletcher S, Roth E, Wu C, Chun A, Horsley V. Calcineurin/Nfatc1 signaling links skin stem cell quiescence to hormonal signaling during pregnancy and lactation. Genes Dev 2014; 28:983-94. [PMID: 24732379 PMCID: PMC4018496 DOI: 10.1101/gad.236554.113] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
In most tissues, the prevailing view is that stem cell (SC) niches are generated by signals from within the nearby tissue environment. Here, we define genetic changes altered in hair follicle (HF) SCs in mice treated with a potent SC activator, cyclosporine A (CSA), which inhibits the phosphatase calcineurin (CN) and the activity of the transcription factor nuclear factor of activated T cells c1 (Nfatc1). We show that CN/Nfatc1 regulates expression of prolactin receptor (Prlr) and that canonical activation of Prlr and its downstream signaling via Jak/Stat5 drives quiescence of HF SCs during pregnancy and lactation, when serum prolactin (Prl) levels are highly elevated. Using Prl injections and genetic/pharmacological loss-of-function experiments in mice, we show that Prl signaling stalls follicular SC activation through its activity in the skin epithelium. Our findings define a unique CN-Nfatc1-Prlr-Stat5 molecular circuitry that promotes persistent SC quiescence in the skin.
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Affiliation(s)
- Jill Goldstein
- Department of Molecular, Cell, and Developmental Biology, Yale University, New Haven, Connecticut 06520, USA
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103
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The Drosophila COMPASS-like Cmi-Trr coactivator complex regulates dpp/BMP signaling in pattern formation. Dev Biol 2013; 380:185-98. [DOI: 10.1016/j.ydbio.2013.05.018] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2012] [Revised: 05/01/2013] [Accepted: 05/13/2013] [Indexed: 01/01/2023]
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104
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Abstract
Many organs respond to physiological challenges by changing tissue size or composition. Such changes may originate from tissue-specific stem cells and their supportive environment (niche). The endocrine system is a major effector and conveyor of physiological changes and as such could alter stem cell behavior in various ways. In this review, we examine how hormones affect stem cell biology in four different organs: the ovary, intestine, hematopoietic system, and mammary gland. Hormones control every stage of stem cell life, including establishment, expansion, maintenance, and differentiation. The effects can be cell autonomous or non-cell autonomous through the niche. Moreover, a single hormone can affect different stem cells in different ways or affect the same stem cell differently at various developmental times. The vast complexity and diversity of stem cell responses to hormonal cues allow hormones to coordinate the body's reaction to physiological challenges.
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Affiliation(s)
- Dana Gancz
- Department of Biological Regulation, Weizmann Institute of Science, Rehovot, 76100 Israel; ,
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105
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Xuan T, Xin T, He J, Tan J, Gao Y, Feng S, He L, Zhao G, Li M. dBre1/dSet1-dependent pathway for histone H3K4 trimethylation has essential roles in controlling germline stem cell maintenance and germ cell differentiation in the Drosophila ovary. Dev Biol 2013; 379:167-81. [PMID: 23624310 DOI: 10.1016/j.ydbio.2013.04.015] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2012] [Revised: 03/27/2013] [Accepted: 04/13/2013] [Indexed: 11/28/2022]
Abstract
The Drosophila ovarian germline stem cells (GSCs) constantly experience self-renewal and differentiation, ensuring the female fertility throughout life. The balance between GSC self-renewal and differentiation is exquisitely regulated by the stem cell niche, the stem cells themselves and systemic factors. Increasing evidence has shown that the GSC regulation also involves epigenetic mechanisms including chromatin remodeling and histone modification. Here, we find that dBre1, an E3 ubiquitin ligase, functions in controlling GSC self-renewal and germ cell differentiation via distinct mechanisms. Removal or knock down of dBre1 function in the germline or somatic niche cell lineage leads to a gradual GSC loss and disruption of H3K4 trimethylation in the Drosophila ovary. Further studies suggest that the defective GSC maintenance is attributable to compromised BMP signaling emitted from the stem cell niche and impaired adhesion of GSCs to their niche. On the other hand, dBre1-RNAi expression in escort cells causes a loss of H3K4 trimethylation and accumulation of spectrosome-containing single germ cells in the germarium. Reducing dpp or dally levels suppresses the germ cell differentiation defects, indicating that dBre1 limits BMP signaling activities for the differentiation control. Strikingly, all phenotypes observed in dBre1 mutant ovaries can be mimicked by RNAi-based reduced expression of dSet1, a Drosophila H3K4 trimethylase. Moreover, genetic studies favor that dBre1 interacts with dSet1 in controlling GSC maintenance and germ cell differentiation. Taken together, we identify a dBre1/dSet1-dependent pathway for the H3K4 methylation involved in the cell fate regulation in the Drosophila ovary.
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Affiliation(s)
- Tao Xuan
- MoE Key Laboratory of Developmental Genetics and Neuropsychiatric Diseases, Bio-X Institutes, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, 200240 Shanghai, PR China
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106
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Ables ET, Drummond-Barbosa D. Cyclin E controls Drosophila female germline stem cell maintenance independently of its role in proliferation by modulating responsiveness to niche signals. Development 2013; 140:530-40. [PMID: 23293285 DOI: 10.1242/dev.088583] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Stem cells must proliferate while maintaining 'stemness'; however, much remains to be learned about how factors that control the division of stem cells influence their identity. Multiple stem cell types display cell cycles with short G1 phases, thought to minimize susceptibility to differentiation factors. Drosophila female germline stem cells (GSCs) have short G1 and long G2 phases, and diet-dependent systemic factors often modulate G2. We previously observed that Cyclin E (CycE), a known G1/S regulator, is atypically expressed in GSCs during G2/M; however, it remained unclear whether CycE has cell cycle-independent roles in GSCs or whether it acts exclusively by modulating the cell cycle. In this study, we detected CycE activity during G2/M, reflecting its altered expression pattern, and showed that CycE and its canonical partner, Cyclin-dependent kinase 2 (Cdk2), are required not only for GSC proliferation, but also for GSC maintenance. In genetic mosaics, CycE- and Cdk2-deficient GSCs are rapidly lost from the niche, remain arrested in a G1-like state, and undergo excessive growth and incomplete differentiation. However, we found that CycE controls GSC maintenance independently of its role in the cell cycle; GSCs harboring specific hypomorphic CycE mutations are not efficiently maintained despite normal proliferation rates. Finally, CycE-deficient GSCs have an impaired response to niche bone morphogenetic protein signals that are required for GSC self-renewal, suggesting that CycE modulates niche-GSC communication. Taken together, these results show unequivocally that the roles of CycE/Cdk2 in GSC division cycle regulation and GSC maintenance are separable, and thus potentially involve distinct sets of phosphorylation targets.
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Affiliation(s)
- Elizabeth T Ables
- Department of Biochemistry and Molecular Biology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD 21205, USA
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107
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Hansen M, Flatt T, Aguilaniu H. Reproduction, fat metabolism, and life span: what is the connection? Cell Metab 2013; 17:10-9. [PMID: 23312280 PMCID: PMC3567776 DOI: 10.1016/j.cmet.2012.12.003] [Citation(s) in RCA: 220] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/18/2012] [Revised: 10/23/2012] [Accepted: 12/06/2012] [Indexed: 11/20/2022]
Abstract
Reduced reproduction is associated with increased fat storage and prolonged life span in multiple organisms, but the underlying regulatory mechanisms remain poorly understood. Recent studies in several species provide evidence that reproduction, fat metabolism, and longevity are directly coupled. For instance, germline removal in the nematode Caenorhabditis elegans promotes longevity in part by modulating lipid metabolism through effects on fatty acid desaturation, lipolysis, and autophagy. Here, we review these recent studies and discuss the mechanisms by which reproduction modulates fat metabolism and life span. Elucidating the relationship between these processes could contribute to our understanding of age-related diseases including metabolic disorders.
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Affiliation(s)
- Malene Hansen
- Sanford-Burnham Medical Research Institute, Del E. Webb Neuroscience, Aging and StemCell Research Center, Program of Development and Aging, La Jolla, CA, USA
| | - Thomas Flatt
- Institute of Population Genetics, Department of Biomedical Sciences, Vetmeduni Vienna, Vienna, Austria
- Wissenschaftskolleg zu Berlin, Institute for Advanced Study, Berlin, Germany
- As of December 2012: Department of Ecology and Evolution, University of Lausanne, Lausanne, Switzerland
| | - Hugo Aguilaniu
- Ecole normale supérieure de Lyon; CNRS; Université de Lyon Claude Bernard; Molecular Biology of the Cell Laboratory/UMR5239, Lyon, France
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108
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Yamanaka N, Rewitz KF, O’Connor MB. Ecdysone control of developmental transitions: lessons from Drosophila research. ANNUAL REVIEW OF ENTOMOLOGY 2013; 58:497-516. [PMID: 23072462 PMCID: PMC4060523 DOI: 10.1146/annurev-ento-120811-153608] [Citation(s) in RCA: 414] [Impact Index Per Article: 37.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
The steroid hormone ecdysone is the central regulator of insect developmental transitions. Recent new advances in our understanding of ecdysone action have relied heavily on the application of Drosophila melanogaster molecular genetic tools to study insect metamorphosis. In this review, we focus on three major aspects of Drosophila ecdysone biology: (a) factors that regulate the timing of ecdysone release, (b) molecular basis of stage- and tissue-specific responses to ecdysone, and (c) feedback regulation and coordination of ecdysone signaling.
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Affiliation(s)
- Naoki Yamanaka
- Department of Genetics, Cell Biology and Development, University of Minnesota, Minneapolis, Minnesota 55455
| | - Kim F. Rewitz
- Department of Science, Systems and Models, Roskilde University, 4000 Roskilde, Denmark
| | - Michael B. O’Connor
- Department of Genetics, Cell Biology and Development, University of Minnesota, Minneapolis, Minnesota 55455
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109
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Steroid signaling within Drosophila ovarian epithelial cells sex-specifically modulates early germ cell development and meiotic entry. PLoS One 2012; 7:e46109. [PMID: 23056242 PMCID: PMC3462805 DOI: 10.1371/journal.pone.0046109] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2012] [Accepted: 08/28/2012] [Indexed: 11/28/2022] Open
Abstract
Drosophila adult females but not males contain high levels of the steroid hormone ecdysone, however, the roles played by steroid signaling during Drosophila gametogenesis remain poorly understood. Drosophila germ cells in both sexes initially follow a similar pathway. After germline stem cells are established, their daughters form interconnected cysts surrounded by somatic escort (female) or cyst (male) cells and enter meiosis. Subsequently, female cysts acquire a new covering of somatic cells to form follicles. Knocking down expression of the heterodimeric ecdysteroid receptor (EcR/Usp) or the E75 early response gene in escort cells disrupts 16-cell cyst production, meiotic entry and follicle formation. Escort cells lose their squamous morphology and unsheath germ cells. By contrast, disrupting ecdysone signaling in males does not perturb cyst development or ensheathment. Thus, sex-specific steroid signaling is essential for female germ cell development at the time male and female pathways diverge. Our results suggest that steroid signaling plays an important sex-specific role in early germ cell development in Drosophila, a strategy that may be conserved in mammals.
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110
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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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111
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Xie T. Control of germline stem cell self-renewal and differentiation in the Drosophila ovary: concerted actions of niche signals and intrinsic factors. WILEY INTERDISCIPLINARY REVIEWS-DEVELOPMENTAL BIOLOGY 2012; 2:261-73. [PMID: 24009036 DOI: 10.1002/wdev.60] [Citation(s) in RCA: 79] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
In the Drosophila ovary, germline stem cells (GSCs) physically interact with their niche composed of terminal filament cells, cap cells, and possibly GSC-contacting escort cells (ECs). A GSC divides to generate a self-renewing stem cell that remains in the niche and a differentiating daughter that moves away from the niche. The GSC niche provides a bone morphogenetic protein (BMP) signal that maintains GSC self-renewal by preventing stem cell differentiation via repression of the differentiation-promoting gene bag of marbles (bam). In addition, it expresses E-cadherin, which mediates cell adhesion for anchoring GSCs in the niche, enabling continuous self-renewal. GSCs themselves also express different classes of intrinsic factors, including signal transducers, transcription factors, chromatin remodeling factors, translation regulators, and miRNAs, which control self-renewal by strengthening interactions with the niche and repressing various differentiation pathways. Differentiated GSC daughters, known as cystoblasts (CBs), also express distinct classes of intrinsic factors to inhibit self-renewal and promote germ cell differentiation. Surprisingly, GSC progeny are also dependent on their surrounding ECs for proper differentiation at least partly by preventing BMP from diffusing to the differentiated germ cell zone and by repressing ectopic BMP expression. Therefore, both GSC self-renewal and CB differentiation are controlled by collaborative actions of extrinsic signals and intrinsic factors.
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Affiliation(s)
- Ting Xie
- Stowers Institute for Medical Research, Kansas City, MO, USA; Department of Anatomy and Cell Biology, University of Kansas School of Medicine, Kansas City, KS, USA.
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112
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Ables ET, Laws KM, Drummond-Barbosa D. Control of adult stem cells in vivo by a dynamic physiological environment: diet-dependent systemic factors in Drosophila and beyond. WILEY INTERDISCIPLINARY REVIEWS-DEVELOPMENTAL BIOLOGY 2012; 1:657-74. [PMID: 23799567 DOI: 10.1002/wdev.48] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Adult stem cells are inextricably linked to whole-body physiology and nutrient availability through complex systemic signaling networks. A full understanding of how stem cells sense and respond to dietary fluctuations will require identifying key systemic mediators, as well as elucidating how they are regulated and integrated with local and intrinsic factors across multiple tissues. Studies focused on the Drosophila germline have generated valuable insights into how stem cells are controlled by diet-dependent pathways, and increasing evidence suggests that diverse adult stem cell populations respond to nutrients through similar mechanisms. Systemic signals, including nutrients themselves and diet-regulated hormones such as Insulin/Insulin-like growth factor or steroid hormones, can directly or indirectly affect stem cell behavior by modifying local cell-cell communication or intrinsic factors. The physiological regulation of stem cells in response to nutritional status not only is a fascinating biological problem, but also has clinical implications, as research in this field holds the key to noninvasive approaches for manipulating stem cells in vivo. In addition, given the known associations between diet, stem cells, and cancer risk, this research may inspire novel anticancer therapies.
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Affiliation(s)
- Elizabeth T Ables
- Division of Reproductive Biology, Department of Biochemistry and Molecular Biology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD, USA
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113
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Abstract
Cell-cell signaling and adhesion are critical for establishing tissue architecture during development and for maintaining tissue architecture and function in the adult. Defects in adhesion and signaling can result in mislocalization of cells, uncontrolled proliferation and improper differentiation, leading to tissue overgrowth, tumor formation, and cancer metastasis. An important example is found in the germline. Germ cells that are not incorporated into the gonad exhibit a greater propensity for forming germ cell tumors, and defects in germline development can reduce fertility. While much attention is given to germ cells, their development into functional gametes depends upon somatic gonadal cells. The study of model organisms has provided great insights into how somatic gonadal cells are specified, the molecular mechanisms that regulate gonad morphogenesis, and the role of germline-soma communication in the establishment and maintenance of the germline stem cell niche. This work will be discussed in the context of Drosophila melanogaster.
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Affiliation(s)
- Jennifer C Jemc
- Department of Biology, Johns Hopkins University, Baltimore, MD 21218, USA.
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114
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Abstract
Specialized microenvironments called niches help maintain stem cells in an undifferentiated and self-renewing state. The existence of niches has long been predicted from mammalian studies, but identifying stem cells in their native environments in vivo has remained a challenge in most vertebrates. Many of the mechanistic insights into how niches regulate stem cell maintenance have been obtained using invertebrate models such as Drosophila. Here, we focus on the Drosophila ovarian germline stem cell niche and review recent studies that have begun to reveal how intricate crosstalk between various signaling pathways regulates stem cell maintenance, how the extracellular matrix modulates the signaling output of the niche and how epigenetic programming influences cell development and function both inside and outside the niche to ensure proper tissue homeostasis. These insights will probably inform the study of mammalian niches and how their malfunction contributes to human disease.
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115
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Gancz D, Lengil T, Gilboa L. Coordinated regulation of niche and stem cell precursors by hormonal signaling. PLoS Biol 2011; 9:e1001202. [PMID: 22131903 PMCID: PMC3222635 DOI: 10.1371/journal.pbio.1001202] [Citation(s) in RCA: 88] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2011] [Accepted: 10/17/2011] [Indexed: 11/19/2022] Open
Abstract
In the developing Drosophila ovary, the ecdysone signaling pathway controls the differentiation of both niche and germ line stem cell precursors. Stem cells and their niches constitute units that act cooperatively to achieve adult body homeostasis. How such units form and whether stem cell and niche precursors might be coordinated already during organogenesis are unknown. In fruit flies, primordial germ cells (PGCs), the precursors of germ line stem cells (GSCs), and somatic niche precursors develop within the larval ovary. Together they form the 16–20 GSC units of the adult ovary. We show that ecdysone receptors are required to coordinate the development of niche and GSC precursors. At early third instar, ecdysone receptors repress precocious differentiation of both niches and PGCs. Early repression is required for correct morphogenesis of the ovary and for protecting future GSCs from differentiation. At mid-third instar, ecdysone signaling is required for niche formation. Finally, and concurrent with the initiation of wandering behavior, ecdysone signaling initiates PGC differentiation by allowing the expression of the differentiation gene bag of marbles in PGCs that are not protected by the newly formed niches. All the ovarian functions of ecdysone receptors are mediated through early repression, and late activation, of the ecdysone target gene broad. These results show that, similar to mammals, a brain-gland-gonad axis controls the initiation of oogenesis in insects. They further exemplify how a physiological cue coordinates the formation of a stem cell unit within an organ: it is required for niche establishment and to ensure that precursor cells to adult stem cells remain undifferentiated until the niches can accommodate them. Similar principles might govern the formation of additional stem cell units during organogenesis. Tissue-specific stem cells reside in specialized microenvironments (niches). How the generation of niche cells and resident stem cells is coordinated, and how their correct numerical ratios are regulated, remains poorly understood. Here, we examine the potential mechanisms of this process by analyzing the formation of the fly ovary. Specifically, we uncover a role for ecdysone, which is a steroid hormone renowned for its role in insect molting but that also controls many aspects of larval development in flies and mammals. We find that ecdysone signaling in fly larvae coordinates the development of niche cells relative to their resident germ line stem cells (GSCs). Ecdysone receptors initially serve as repressors of differentiation, allowing precursor cells of both niches and GSCs time to proliferate and attain correct cell numbers. Later, ecdysone receptors allow differentiation of niches while simultaneously maintaining GSC precursors in an undifferentiated state, until the newly formed niches can accommodate them. Finally, ecdysone induces the differentiation of GSC precursors that are not incorporated in niches. Our work exemplifies one possible solution to coordinating stem cell and niche development: using a common signal to affect both cell types. A further understanding of these and other mechanisms will offer novel insights into regeneration and could help guide cell-based therapies for various diseases.
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Affiliation(s)
- Dana Gancz
- Department of Biological Regulation, Weizmann Institute of Science, Rehovot, Israel
| | - Tamar Lengil
- Department of Biological Regulation, Weizmann Institute of Science, Rehovot, Israel
| | - Lilach Gilboa
- Department of Biological Regulation, Weizmann Institute of Science, Rehovot, Israel
- * E-mail:
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116
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Alkhatib SG, Landry JW. The nucleosome remodeling factor. FEBS Lett 2011; 585:3197-207. [PMID: 21920360 PMCID: PMC4839296 DOI: 10.1016/j.febslet.2011.09.003] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2011] [Revised: 09/02/2011] [Accepted: 09/02/2011] [Indexed: 12/19/2022]
Abstract
An essential component of the chromatin remodeling machinery is NURF (Nucleosome Remodeling Factor), the founding member of the ISWI family of chromatin remodeling complexes. In vertebrates and invertebrates alike, NURF has many important functions in chromatin biology including regulating transcription, establishing boundary elements, and promoting higher order chromatin structure. Since NURF is essential to many aspects of chromatin biology, knowledge of its function is required to fully understand how the genome is regulated. This review will summarize what is currently known of its biological functions, conservation in the most prominent model organisms, biochemical functions as a nucleosome remodeling enzyme, and its possible relevance to human cancer.
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Affiliation(s)
- Suehyb G. Alkhatib
- Department of Human and Molecular Genetics, Virginia Commonwealth University School of Medicine, Richmond, VA 23298, United States
| | - Joseph W. Landry
- Department of Human and Molecular Genetics, Virginia Commonwealth University School of Medicine, Richmond, VA 23298, United States
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117
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Losick VP, Morris LX, Fox DT, Spradling A. Drosophila stem cell niches: a decade of discovery suggests a unified view of stem cell regulation. Dev Cell 2011; 21:159-71. [PMID: 21763616 PMCID: PMC6894370 DOI: 10.1016/j.devcel.2011.06.018] [Citation(s) in RCA: 241] [Impact Index Per Article: 18.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2011] [Revised: 06/03/2011] [Accepted: 06/10/2011] [Indexed: 12/28/2022]
Abstract
The past decade of research on Drosophila stem cells and niches has provided key insights. Fly stem cells do not occupy a special "state" based on novel "stem cell genes" but resemble transiently arrested tissue progenitors. Moreover, individual stem cells and downstream progenitors are highly dynamic and dispensable, not tissue bulwarks. Niches, rather than fixed cell lineages, ensure tissue health by holding stem cells and repressing cell differentiation inside, but not outside. We review the five best-understood adult Drosophila stem cells and argue that the fundamental biology of stem cells and niches is conserved between Drosophila and mice.
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Affiliation(s)
- Vicki P Losick
- Howard Hughes Medical Institute Research Laboratories, Department of Embryology, Carnegie Institution for Science, 3520 San Martin Drive, Baltimore, MD 21218, USA
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118
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Intrinsic Epigenetic Factors Cooperate with the Steroid Hormone Ecdysone to Govern Dendrite Pruning in Drosophila. Neuron 2011; 72:86-100. [DOI: 10.1016/j.neuron.2011.08.003] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/03/2011] [Indexed: 01/23/2023]
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119
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Belacortu Y, Paricio N. Drosophila as a model of wound healing and tissue regeneration in vertebrates. Dev Dyn 2011; 240:2379-404. [PMID: 21953647 DOI: 10.1002/dvdy.22753] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/06/2011] [Indexed: 11/11/2022] Open
Abstract
Understanding the molecular basis of wound healing and regeneration in vertebrates is one of the main challenges in biology and medicine. This understanding will lead to medical advances allowing accelerated tissue repair after wounding, rebuilding new tissues/organs and restoring homeostasis. Drosophila has emerged as a valuable model for studying these processes because the genetic networks and cytoskeletal machinery involved in epithelial movements occurring during embryonic dorsal closure, larval imaginal disc fusion/regeneration, and epithelial repair are similar to those acting during wound healing and regeneration in vertebrates. Recent studies have also focused on the use of Drosophila adult stem cells to maintain tissue homeostasis. Here, we review how Drosophila has contributed to our understanding of these processes, primarily through live-imaging and genetic tools that are impractical in mammals. Furthermore, we highlight future research areas where this insect may provide novel insights and potential therapeutic strategies for wound healing and regeneration.
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Affiliation(s)
- Yaiza Belacortu
- Departamento de Genética, Facultad CC Biológicas, Universidad de Valencia, Burjasot, Spain
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120
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Abstract
In metazoans, tissue maintenance and regeneration depend on adult stem cells, which are characterized by their ability to self-renew and generate differentiating progeny in response to the needs of the tissues in which they reside. In the Drosophila testis, germline and somatic stem cells are housed together in a common niche, where they are regulated by local signals, epigenetic mechanisms and systemic factors. These stem cell populations in the Drosophila testis have the unique advantage of being easy to identify and manipulate, and hence much progress has been made in understanding how this niche operates. Here, we summarize recent work on stem cells in the adult Drosophila testis and discuss the remarkable ability of these stem cells to respond to change within the niche.
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Affiliation(s)
- Margaret de Cuevas
- Department of Cell Biology, Johns Hopkins School of Medicine, 725 N. Wolfe Street, Baltimore, MD 21205, USA.
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121
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Casper AL, Baxter K, Van Doren M. no child left behind encodes a novel chromatin factor required for germline stem cell maintenance in males but not females. Development 2011; 138:3357-66. [PMID: 21752937 DOI: 10.1242/dev.067942] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Male and female germ cells follow distinct developmental paths with respect to germline stem cell (GSC) production and the types of differentiated progeny they produce (sperm versus egg). An essential aspect of germline development is how sexual identity is used to differentially regulate the male and female germ cell genomes to allow for these distinct outcomes. Here, we identify a gene, no child left behind (nclb), that plays very different roles in the male versus female germline in Drosophila. In particular, nclb is required for GSC maintenance in males, but not in females. Male GSCs mutant for nclb are rapidly lost from the niche, and begin to differentiate but cannot complete spermatogenesis. We further find that nclb encodes a member of a new family of conserved chromatin-associated proteins. NCLB interacts with chromatin in a specific manner and is associated with sites of active transcription. Thus, NCLB appears to be a novel chromatin regulator that exhibits very different effects on the male and female germ cell genomes.
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Affiliation(s)
- Abbie L Casper
- Biology Department, Johns Hopkins University, Baltimore, MD 21218, USA
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122
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Cease and desist: modulating short-range Dpp signalling in the stem-cell niche. EMBO Rep 2011; 12:519-26. [PMID: 21546910 PMCID: PMC3128284 DOI: 10.1038/embor.2011.80] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2011] [Accepted: 04/07/2011] [Indexed: 01/25/2023] Open
Abstract
Drosophila ovarian germline stem cells (GSCs) are maintained by the extracellular BMP2/4 orthologue Dpp, which is produced from the surrounding somatic niche. The Dpp signal has a short range; it induces a response in GSCs within the niche, but is rapidly extinguished in their progeny only one cell-diameter away. To ensure the correct balance between stem-cell maintenance and differentiation, several regulatory mechanisms that modulate the Dpp signal at many stages of the pathway have been described. Here, we discuss the nature of the ovarian Dpp signal and review the catalogue of mechanisms that regulate it, demonstrating how the exquisite modulation of Dpp signalling in this context can result in precise and robust control of stem-cell fate. This modulation is applicable to other stem-cell environments that use BMPs as a niche signal, and the regulatory mechanisms are conceptually relevant to several other stem-cell systems.
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123
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König A, Yatsenko AS, Weiss M, Shcherbata HR. Ecdysteroids affect Drosophila ovarian stem cell niche formation and early germline differentiation. EMBO J 2011; 30:1549-62. [PMID: 21423150 PMCID: PMC3102283 DOI: 10.1038/emboj.2011.73] [Citation(s) in RCA: 94] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2010] [Accepted: 02/22/2011] [Indexed: 01/13/2023] Open
Abstract
Previously, it has been shown that in Drosophila steroid hormones are required for progression of oogenesis during late stages of egg maturation. Here, we show that ecdysteroids regulate progression through the early steps of germ cell lineage. Upon ecdysone signalling deficit germline stem cell progeny delay to switch on a differentiation programme. This differentiation impediment is associated with reduced TGF-β signalling in the germline and increased levels of cell adhesion complexes and cytoskeletal proteins in somatic escort cells. A co-activator of the ecdysone receptor, Taiman is the spatially restricted regulator of the ecdysone signalling pathway in soma. Additionally, when ecdysone signalling is perturbed during the process of somatic stem cell niche establishment enlarged functional niches able to host additional stem cells are formed.
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Affiliation(s)
- Annekatrin König
- Max Planck Research Group of Gene Expression and Signaling, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
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124
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Negri I. Wolbachia as an "infectious" extrinsic factor manipulating host signaling pathways. Front Endocrinol (Lausanne) 2011; 2:115. [PMID: 22654845 PMCID: PMC3356060 DOI: 10.3389/fendo.2011.00115] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/09/2011] [Accepted: 12/21/2011] [Indexed: 11/13/2022] Open
Abstract
Wolbachia pipientis is a widespread endosymbiont of filarial nematodes and arthropods. While in worms the symbiosis is obligate, in arthropods Wolbachia induces several reproductive manipulations (i.e., cytoplasmic incompatibility, parthenogenesis, feminization of genetic males, and male-killing) in order to increase the number of infected females. These various phenotypic effects may be linked to differences in host physiology, and in particular to endocrine-related processes governing growth, development, and reproduction. Indeed, a number of evidences links Wolbachia symbiosis to insulin and ecdysteroid signaling, two multilayered pathways known to work antagonistically, jointly or even independently for the regulation of different molecular networks. At present it is not clear whether Wolbachia manipulates one pathway, thus affecting other related metabolic networks, or if it targets both pathways, even interacting at several points in each of them. Interestingly, in view of the interplay between hormone signaling and epigenetic machinery, a direct influence of the "infection" on hormonal signaling involving ecdysteroids might be achievable through the manipulation of the host's epigenetic pathways.
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Affiliation(s)
- Ilaria Negri
- Department of Exploitation and Protection of the Agricultural and Forestry Resources, Università di TorinoGrugliasco, Italy
- Koiné – Environmental ConsultingParma, Italy
- *Correspondence: Ilaria Negri, Department of Exploitation and Protection of the Agricultural and Forestry Resources, Università di Torino, Via L. da Vinci, 44, 10095 Grugliasco, Italy. e-mail:
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