Xie T. In the germarium of the Drosophila ovary, developing germline cysts are surrounded by a population of so-matic escort cells that are known to function as the niche cells for germline differentiation;1 however, the un-derlying molecular mechanisms of this niche function remain poorly understood. these niche escort cells are also targets. Multiple escort cells surround region 2a cysts and contact the FSC niche. , Spradling A. Differentiation of germline stem cells (GSCs) in the Drosophila ovary is induced by somatic escort cells (ECs), which extend membrane protrusions encapsulating the. (A,B) Germaria stained for HA (green), to label the transgene, Hts (red), to label fusomes, and DNA (blue) (Scale bars, 10 µM). Stem cells cycle between periods of quiescence and proliferation to promote tissue health. To carefully examine what cell types in the niche express Notch ligands, we first attempted to use available antibodies against Delta and. melanogaster Cap cell Figure 1. Escort cells are cells that are intermingled with GSCs and differentiating germ cells. The germarium is located at the anterior. Drosophila germ cells in both sexes initially. The proposed role of the JAK/STAT pathway is to maintain the T he stem cell niche, formed by surrounding stromal cells, provides extrinsic signals that maintain stem cell self-renewal. PLoS Genet 13 , e1006790,. Although extensively used as a stem cell model, heterogeneity in gene expression has. Sir2, Escort cell, Drosophila, Dpp, Germline stem cell Running Title. in ECs upregulates Dpp signalling giving rise to tumorous germaria. Decapentaplegic (Dpp) is secreted from the germline stem cell (GSC) niche to activate Bone Morphogenic Protein (BMP) signaling in GSCs for their self-renewal and is restricted in the differentiation niche for daughter cell differentiation. Drosophila Piwi is the founding member of a gonadal clade of Argonaute proteins that serve as silencing effectors for ∼26–32 nt Piwi-interacting RNAs (piRNAs) [1], and piwi mutants exhibit dramatically rudimentary ovaries [2]. In Drosophila ovaries, germline stem cells depend on cap cells for self-renewing signals and physical attachment. The ovarian niche is made up of somatic cells namely Terminal Filament cells (TFCs), Cap cells (CpCs) and Escort Cells (ECs) (Decotto and Spradling, 2005; Xie and Spradling, 1998). A niche maintaining germ line stem cells in the Drosophila ovary. However, it remains largely unknown what constitutes a functional niche and how niche formation is controlled. , 2012). While both contain germline stem cells, the testis niche also contains “cyst progenitor” stem cells, which divide to produce somatic cells that encase developing germ cells. Decapentaplegic (Dpp) is required to maintain the anterior stem cells, whereas. The Drosophila genome encodes 18 nuclear receptors (representing all major subfamilies of vertebrate receptors) (King-Jones and Thummel, 2005; Mazaira et al. 1The Drosophila male and female gonads are among the best-characterized stem cell niches and have elucidated aspects of stem cell signal transduction, niche-stem cell interactions, and stem cell. Development. This approach enables the study of ovarian germline and somatic cell. , 2004; Wang and Page-McCaw, 2018; Xie and Spradling. The egg production of Catsup RNAi gradually decreased every day and approached. Wg has been suggested as a candidate niche factor derived from the escort cells and Wg signaling is critical for. The anterior-most structure of the ovariole is the germarium ; the anterior tip of the germarium is constructed from a terminal filament (TF), 4-6 cap cells and anterior escort cells, which together create a germline stem cell (GSC) niche that houses two to three GSCs (Wong et al. Development. GSC maintenance depends on bone morphogenetic protein (BMP) signals produced by a small cluster of cap cells located at the anterior tip of the germarium. 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. A population of stromal escort cells located just anterior to the FSCs forms the niche,. It has been proposed that escort stem cells. Within the germarium are terminal filament cells (TFCs; purple) and cap cells (CCs; red), escort cells (ECs; blue), germline stem cells. (A to I) The germaria of flies of the indicated genotypes doubly stained with anti-Vasa and monoclonal antibody (mAb) 1B1. 2020. Primordial germ cells (PGCs), each with a round-shaped fusome (unique membrane-enriched organelle), and somatic gonad precursors (SGPs) are present at the L1 and L2 stages. USP expression remains within germ cells of the germaria (region 2b germ cells marked by asterisk, note that there are no region 3 germ cells within this germarium). Introduction. The stem cell niches at the apex of Drosophila ovaries and testes have been viewed as distinct in two major respects. Thus, dSETDB1 regulates dWnt4 in the escort cells of germaria to promote CB differentiation. Wild-type germarium. 5%) and the third week (83. The GSCN is a somatic structure at the anterior tip of the. Dev. Drosophila germline stem cells (GSCs) and their niches are an attractive system for studying the interactions between stem cells and the niche [3,4]. Furthermore, line #2126 had expression in escort cells of 8-week-old flies in the absence of RU486. Decapentaplegic (Dpp) is secreted from the germline stem cell (GSC) niche to activate Bone Morphogenic Protein (BMP) signaling in GSCs for their self-renewal and is restricted in the differentiation niche for daughter cell differentiation. 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. Kai T, Spradling A. While both contain germline stem cells, the testis niche also contains “cyst progenitor” stem cells, which divide to produce somatic cells that encase developing germ cells. 1998; 94:251–260. Additionally, in another fruit fly, Drosophila mauritiana, Wolbachia also target the germ-line stem-cell niche (GSCN; Fig. Each Drosophila ovariole has three independent sets of stem cells: germ-line stem cells (GSCs) and escort stem cells, located at the anterior tip of the germarium, and somatic stem cells (SSCs), located adjacent to the newly formed 16-cell cysts. Their results show that hemocyte-derived CollIV is essential for stem cell niche organization. The histone demethylase Lsd1 functions within escort cells to limit niche size in the ovary (Eliazer et al,. In Drosophila ovaries, germline stem cells depend on cap cells for self-renewing signals and physical attachment. Dev. GSCs (red) reside in a niche, comprising somatic cells such as cap cells (orange), terminal filament, and escort stem cells. The Wnt pathway limits BMP signaling outside of the germline stem cell niche in Drosophila ovaries. In the Drosophila female germline stem cell (GSC) niche, Decapentaplegic (DPP) is an important niche factor for GSC self-renewal. (C–E) Graphs indicating the frequencies of the Egfr f24 or control FSC clones at 2, 4, 7, and 11 dpci (C); all Egfr f24 or control clones, including polarity-defective Egfr f24 prefollicle cell (PFC) clones, at 2 dpci. 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. The Drosophila melanogaster ovary is an excellent model system for understanding the function of stem cell niches (). 1A) (6–8). Proposed model of c-Fos repression by Piwi in the somatic niche (cap cells and escort cells) to influence GSCs and in the somatic/follicle cells to. , 2013. Although cap cells and escort cells (ESCs) are shown to form the niche for the GSCs in the Drosophila ovary, here we only used cap cell number to study the niche structure change with age because cap cells are a reliably identifiable niche component but ESCs are not (Decotto and Spradling, 2005, Xie and Spradling, 2000). The stem cell niche is called the hub (dark blue), which is a cluster of 10–12 densely packed somatic cells. doi. After GSC After GSC divides, one daughter cell that remains attached to the niche cells retains its. The mechanisms that modulate and limit the signaling output of adult stem cell niches remain poorly understood. elegans GSCs –; however, the mechanisms underlying such depletion remain unknown. , 2005). A–C) Escort and early follicle cell processes (labeled with anti-Fax) entirely surround each germline cyst and early follicle in control germaria (A, red arrows) but are completely (B) or. (A) The female adult fly has a pair of ovaries. Stem cell self-renewal is controlled by concerted actions of niche signals and intrinsic factors in a variety of systems. Here, we use Drosophila ovarian germline stem cells (GSCs) as a model to demonstrate that age-dependent decline in the functions of. Drosophila ovarian germline stem cells (GSCs) have been one of the most productive systems for identifying the factors controlling self-renewal. Studies on three stem cells in the Drosophila ovary have produced several general principles for stem cell biology: 1) The stem cell niche exhibits structural asymmetry, which ensures that one of. In the germarium of the Drosophila ovary, developing germline cysts are surrounded by a population of so-matic escort cells that are known to function as the niche cells for germline differentiation;1 however, the un-derlying molecular mechanisms of this niche function remain poorly understood. The germline stem cell niche of the Drosophila ovary has been a long-standing model for the analysis of the interactions between stem cells and niche cells. 1228. (Escort cells) c587-GAL4> (Escort cells) c587-GAL4> (Escort cells) Female D. Early in the characterization of the stem cell niche,. It has been proposed that escort stem cells. Here we use single-cell RNA-sequencing (scRNA-seq) to build a comprehensive cell atlas of the adult Drosophila. (A) Diagram of Drosophila ovariole showing the anterior germarium followed by progressively older follicles, each of which contains a 16-cell germline cyst (15 nurse cells and one oocyte; light blue) surrounded by follicle cells (gray). Specification and spatial arrangement of cells in the germline stem cell niche of the Drosophila ovary depend on the Maf transcription factor Traffic jam. (A) Control and (B) Laminin-depleted germaria stained to show DNA (blue), PH3 (white) and Fas3 (red). Drosophila germline stem cells (GSCs) and their niches are an attractive system for studying the interactions between stem cells and the niche [3,4]. The GSCN is a somatic structure at the anterior tip of the germarium, composed of terminal filament (TF) and cap cells (CC) ( Fig. A. Surprisingly little is known, however, about the mechanisms that pattern this niche, leading to the. Here, we use the Drosophila germline stem cell (GSC) niche as a model system and show that GSCs signal to the niche through the Notch signaling pathway. The niche, comprising three types of somatic cells—terminal filament (TF) cells, cap cells, and escort stem cells (ESCs) ()—supports two to three self-renewing GSCs by providing niche-associated. In the Drosophila ovary, germline stem cells (GSCs),. However, the mechanism regulating dpp expression in the niche is largely unknown. (A to I) The germaria of flies of the indicated genotypes doubly stained with anti-Vasa and monoclonal antibody (mAb) 1B1. The Drosophila germline stem cells (GSCs) reside in a somatic cell niche [1, 2]. Gilboa L. Stem cell function depends on proper input from their environment. The exact. (B,C) GFP::par-1, nanos>tkv Act germaria showing the typical asymmetric division of a GSC inside the niche from ‘round-G1’ until the ‘exclamation point’ phase (t=0′, NEP) (B) and the division of a GSC-like tumour cell outside the niche (C). 10. Cap cells, escort cells and terminal filament cells are responsible for producing niche signals that permit the maintenance of GSCs in their undifferentiated state . Open in a separate window. Loss of the highly conserved histone demethylase Lsd1 in Drosophila escort cells results in increased BMP signaling outside the cap cell niche and an expanded germline stem cell (GSC) phenotype. At the anterior tip of the germarium, a stem cell maintenance niche is formed by terminal filament (TF) cells, cap cells (the major component), and the anterior-most escort cells. 1A, green cells) in long-term maternally infected flies (). Niche associated somatic escort cells are likely involved,. Proc Natl Acad. However, we find that these escort cells present at the niche do not extend processes that promote differentiation. Development. Arrowheads point to spectrosome of GSCs that are in contact with niche cells. (C–D) Frequencies of germaria containing 1, 2, and 3 GSCs (left vertical axis) and the. Besides the complex signaling. We next asked if maintenance of the germline stem cells was affected in dlp overexpressing germaria. Because recent studies have indicated the expression of Mmp2 in niche cells, including escort cells (Pearson et al. Download scientific diagram | Defective Rho signaling in ECs disrupts EC-germ cell interactions and germ cell differentiation. The germline stem cell niche, comprised of anterior escort cells and cap cells, secretes Dpp ligand to promote Dpp signaling in the germline stem cells to maintain their stemness (Song et al. The stem cell niches at the apex of Drosophila ovaries and testes have been viewed as distinct in two major respects. 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. The Drosophila ovary is an effective model for studying niche functions in regulating germline stem cell (GSC) self-renewal and differentiation. Biol. Each ovary is comprised of 16–18 sequential chains of egg chambers. Only posterior FSCs can directly become proliferative follicle cells (FCs) and they also divide much faster than their anterior FSC neighbors, which can directly become quiescent escort cells (ECs) . The adult Drosophila ovary is an excellent model for the study of stem cell behaviour and organ morphogenesis. Results and Discussion. 1006/dbio. In the Drosophila ovary, somatic escort cells (ECs) form a niche that promotes differentiation of germline stem cell (GSC) progeny. Cartoon models illustrating H1-mediated regulation of germ cell differentiation in escort cells in germaria. which is composed of terminal filament, cap cells, and anterior escort cells [10,11]. ch11. We performed a pilot genetic screen where clonal germaria of hsFlp;FRT40A lethals (DGRC) were analysed in order to find novel genes that affect stem cell niche architecture. In each ovariole, two to three germline stem cells (GSCs) reside at the anterior tip where they directly contact a supporting niche composed of five to seven somatic cells, named cap cells (Xie and. •. No unrecombined cells remain near the FSC niches (arrows). , 2020). The Drosophila melanogaster ovarian niche is established by several types of stromal cells, including terminal filament cells, cap cells, and escort cells (ECs). DOI: 10. Active areas of research in Drosophila germaria include stem cell self-renewal, division, and. (C) Knockdown of vkg expression in larval haemocytes extends the range of Dpp in the germarium, leading to ectopic germ cell accumulation and cytocensor formation by cells that have exited the niche (inset). Germline stem cell division and egg chamber development in transplanted Drosophila germaria. A Drosophila fertility gene is identified that acts as a linker between HP1a and local H3K4 demethylation during HP1a-mediated gene silencing that is required for ovary development and transposon silencing. Germ cells are first wrapped by escort cells and then by follicle cells, which are derived from follicle stem cells (FSCs), to form egg chambers. . Europe PMC is an archive of life sciences journal literature. The spectrosome is initially opposite the place of cytokinesis. In Drosophila,. 10. (C-G) Germaria of. Our finding of a progressive niche for germline development in Drosophila is likely conserved in mammals: a recent study revealed the presence of escort-like somatic cells and the derived granulosa cells in mouse fetal ovaries and showed that these cells interact with germ cells and developing germline cysts. 1 In these studies, Calvin Bridges observed that in diploid cells sex is. We next asked if maintenance of the germline stem cells was affected in dlp overexpressing germaria. The existence of specialised regulatory microenvironments or niches that sustain stable stem cell populations is well documented in many tissues. It is now widespread in Coastal and Interior. Stem cells reside in a niche, a local environment whose cellular and molecular complexity is still being elucidated. , 2011; Sahai-Hernandez et al. Development 145, dev159186 10. Introduction. In Drosophila, reciprocal signals between germline and escort (in female). Besides, the escort cells in the drosophila germinal stem cell niche directly affect FGSCs via GTPaseRho regulation and functional defect of Rho increase abnormal BMP level in the niche, leading. Fig. The existence of specialised regulatory microenvironments or niches that sustain stable stem cell populations is well documented in many tissues. Females produce eggs for months, despite the 4- to 5-week half-life of an individual stem cell . although 80% of sxl- and abd-A-KD germaria contained at least four cap cells (an average of 4. Loss of lysine-specific demethylase 1 nonautonomously causes stem cell tumors in the Drosophila ovary. 2B,C,E,F). B shows a germarium that was not stained with anti-ß-gal antibodies. C. Although niches are important to maintain “stemness” in a wide variety of tissues, control of these niches is poorly understood. Notch signaling controls germline stem cell niche formation in the Drosophila ovary. 1A, green cells) in long-term maternally infected flies (). Although niches are important to maintain “stemness” in a wide variety of tissues, control of these niches is poorly understood. The starvation-induced sisRNA, sisR-2, represses GSC maintenance via a fatty acid metabolism gene dFAR1. Furthermore, line #2126 had expression in escort cells of 8-week-old flies in the absence of RU486. , 2020; Zhang and Cai, 2020). A dynamic population of stromal cells contributes to the follicle stem cell niche in the Drosophila ovary. A Drosophila fertility gene is identified that acts as a linker between HP1a and local H3K4 demethylation during HP1a-mediated gene silencing that is required for ovary development and transposon silencing. in the germaria of ovaries (e. While control germaria contained on average 6 niche cells, tai mutant niches consisted of 7–10 CpCs (Figure 1D,. 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.