scholarly journals Zebrafish dazl regulates cystogenesis and germline stem cell specification during the primordial germ cell to germline stem cell transition

Development ◽  
2021 ◽  
Vol 148 (7) ◽  
Author(s):  
Sylvain Bertho ◽  
Mara Clapp ◽  
Torsten U. Banisch ◽  
Jan Bandemer ◽  
Erez Raz ◽  
...  
Keyword(s):  
Stem Cells ◽  
Stem Cell ◽  
Rna Binding ◽  
Process Analysis ◽  
Primordial Germ Cell ◽  
Cyst Formation ◽  
Rapid Expansion ◽  
Germline Stem Cell ◽  
Cell Specification ◽  
Ring Canals

ABSTRACT Fertility and gamete reserves are maintained by asymmetric divisions of the germline stem cells to produce new stem cells or daughters that differentiate as gametes. Before entering meiosis, differentiating germ cells (GCs) of sexual animals typically undergo cystogenesis. This evolutionarily conserved process involves synchronous and incomplete mitotic divisions of a GC daughter (cystoblast) to generate sister cells connected by intercellular bridges that facilitate the exchange of materials to support rapid expansion of the gamete progenitor population. Here, we investigated cystogenesis in zebrafish and found that early GCs are connected by ring canals, and show that Deleted in azoospermia-like (Dazl), a conserved vertebrate RNA-binding protein (Rbp), is a regulator of this process. Analysis of dazl mutants revealed the essential role of Dazl in regulating incomplete cytokinesis, germline cyst formation and germline stem cell specification before the meiotic transition. Accordingly, dazl mutant GCs form defective ring canals, and ultimately remain as individual cells that fail to differentiate as meiocytes. In addition to promoting cystoblast divisions and meiotic entry, dazl is required for germline stem cell establishment and fertility.

scholarly journals Zebrafish dazl regulates cystogenesis upstream of the meiotic transition and germline stem cell specification and independent of meiotic checkpoints

2019 ◽  
Author(s):  
Sylvain Bertho ◽  
Mara Clapp ◽  
Torsten U. Banisch ◽  
Jan Bandemer ◽  
Erez Raz ◽  
...  
Keyword(s):  
Stem Cells ◽  
Stem Cell ◽  
Rna Binding ◽  
Process Analysis ◽  
Cyst Formation ◽  
Germline Stem Cell ◽  
Germline Stem Cells ◽  
Asymmetric Divisions ◽  
Germline Cyst ◽  
Deleted In Azoospermia

AbstractFertility and gamete reserves are maintained by asymmetric divisions of the germline stem cells to produce new stem cells or daughters that differentiate as gametes. Before entering meiosis, differentiating germ cells (GCs) of sexual animals typically undergo cystogenesis. This evolutionary conserved process involves synchronous and incomplete mitotic divisions of a germ cell daughter (cystoblast) to generate sister cells connected by stable intercellular bridges that facilitate exchange of materials to support a large synchronous population of gamete progenitors. Here we investigate cystogenesis in zebrafish and identified Deleted in azoospermia (Dazl), a conserved vertebrate RNA binding protein as a regulator of this process. Analysis of dazl mutants revealed an essential role for Dazl in regulating incomplete cytokinesis and germline cyst formation before the meiotic transition. Accordingly, dazl mutant GCs form defective ring canals, and ultimately remain as individual cells that fail to differentiate as meiocytes. In addition to promoting cystoblast divisions and meiotic entry, dazl function is required upstream of germline stem cell establishment and fertility.Summary StatementWe show that zebrafish dazl is required for incomplete cytokinesis to generate germline cysts during cystogenesis, acts upstream of germline stem cell establishment, and is required for meiosis, and fertility.

Nanos and Pumilio have critical roles in the development and function of Drosophila germline stem cells

Development ◽  
1998 ◽  
Vol 125 (4) ◽  
pp. 679-690 ◽  
Author(s):  
A. Forbes ◽  
R. Lehmann
Keyword(s):  
Stem Cells ◽  
Stem Cell ◽  
Germ Cells ◽  
Rna Binding ◽  
Drosophila Embryo ◽  
Germline Stem Cell ◽  
Germline Stem Cells ◽  
Embryonic Patterning ◽  
Germline Development ◽  
Egg Chambers

The zinc-finger protein Nanos and the RNA-binding protein Pumilio act together to repress the translation of maternal hunchback RNA in the posterior of the Drosophila embryo, thereby allowing abdomen formation. nanos RNA is localized to the posterior pole during oogenesis and the posteriorly synthesized Nanos protein is sequestered into the germ cells as they form in the embryo. This maternally provided Nanos protein is present in germ cells throughout embryogenesis. Here we show that maternally deposited Nanos protein is essential for germ cell migration. Lack of zygotic activity of nanos and pumilio has a dramatic effect on germline development of homozygous females. Given the coordinate function of nanos and pumilio in embryonic patterning, we analyzed the role of these genes in oogenesis. We find that both genes act in the germline. Although the nanos and pumilio ovarian phenotypes have similarities and both genes ultimately affect germline stem cell development, the focus of these phenotypes appears to be different. While pumilio mutant ovaries fail to maintain stem cells and all germline cells differentiate into egg chambers, the focus of nanos function seems to lie in the differentiation of the stem cell progeny, the cystoblast. Consistent with the model that nanos and pumilio have different phenotypic foci during oogenesis, we detect high levels of Pumilio protein in the germline stem cells and high levels of Nanos in the dividing cystoblasts. We therefore suggest that, in contrast to embryonic patterning, Nanos and Pumilio may interact with different partners in the germline.

scholarly journals PUF family proteins FBF-1 and FBF-2 regulate germline stem and progenitor cell proliferation and differentiation in C. elegans

2019 ◽  
Author(s):  
Xiaobo Wang ◽  
Mary Ellenbecker ◽  
Benjamin Hickey ◽  
Nicholas J. Day ◽  
Ekaterina Voronina
Keyword(s):  
Stem Cells ◽  
Cell Proliferation ◽  
Stem Cell ◽  
Translational Control ◽  
Rna Binding ◽  
Germline Stem Cell ◽  
C Elegans ◽  
Cell Proliferation And Differentiation ◽  
Proliferation And Differentiation ◽  
Puf Family

ABSTRACTStem cells support tissue maintenance, but the mechanisms that balance the rate of stem cell self-renewal with differentiation at a population level remain uncharacterized. Through investigating the regulation of germline stem cells by two PUF family RNA-binding proteins FBF-1 and FBF-2 in C. elegans, we find that FBF-1 restricts differentiation, while FBF-2 promotes both proliferation and differentiation. FBFs act on a shared set of target mRNAs; however, FBF-1 destabilizes target transcripts, while FBF-2 promotes their accumulation. These regulatory differences result in complementary effects of FBFs on stem cells. We identify a mitotic cyclin as one of the targets affecting stem cell homeostasis. FBF-1-mediated translational control requires the activity of CCR4-NOT deadenylase. Distinct abilities of FBFs to cooperate with CCR4-NOT depend on protein sequences outside of the conserved PUF family RNA-binding domain. We propose that the combination of FBF activities regulates the dynamics of germline stem cell proliferation and differentiation.

57 Primordial germ cell distribution in the horse fetal gonad

2020 ◽  
Vol 32 (2) ◽  
pp. 154
Author(s):  
D. Scarlet ◽  
U. Reichart ◽  
G. Podico ◽  
R. Ellerbrock ◽  
I. Canisso ◽  
...  
Keyword(s):  
Stem Cells ◽  
Stem Cell ◽  
Germ Cell ◽  
Primordial Germ Cell ◽  
Temporal Distribution ◽  
Germline Stem Cell ◽  
Female Gonad ◽  
Specific Marker ◽  
Cortical Region ◽  
Germ Cell Differentiation

Germ cell development and differentiation is a complex process associated with down-regulation of stem cell-associated genes and up-regulation of markers of germ cell differentiation and meiosis. In horses, putative primordial germ cells (PGCs) were identified outside the gonads starting 20 days after ovulation (Curran et al. 1997 Equine Vet. J. Suppl. 25, 72-76). However, no information is available after the time when these cells enter the gonad. The aim of this study was to identify, localise, and quantify PGCs in fetal male and female gonads. Twelve (5 males and 7 females) equine fetuses were collected transcervically 60 days after ovulation. Fetuses were entirely fixed in formaldehyde and gonads were subsequently localised. Fetal gonads underwent multiplex immunofluorescence staining for pre-meiotic germ cell marker LIN28, stem-cell associated marker CD117, and cell proliferation marker Ki67. Specificity of the primary antibodies for equine samples has been first validated. Quantification of fluorescence positive areas for LIN28, CD117, and Ki67 in the fetal gonads was done using a macro for ImageJ. Furthermore, we analysed the co-localization of above-mentioned markers using the same macro. Statistical comparison for differences between males and females was performed using non-parametric tests. In both sexes, PGCs proliferated as determined by double immunofluorescence of Ki67 and LIN28. Protein expression of LIN28 and Ki67 was highly correlated (r=0.92; P=0.003). In the fetal female gonad, PGCs were organised in cord-like structures localised in the cortical region, but there were also LIN28+ cells in the surface germinal epithelium. In the fetal male gonad, PGCs were restricted to the already developed tubular structures. Fewer LIN28+ cells (3.0±0.4% vs. 4.5±0.3%; P<0.05) were present in female than in male gonads. The distribution pattern of the stem cell factor receptor CD117 was similar to LIN28, as 86.8±3.2% of LIN28+ cells in females and 84.6±4.7% in males were also CD117+. However, immunofluorescent co-localization analysis revealed a subpopulation of CD117+ cells (43.1±8.1% in females and 46.1±6.1% in males), which did not show an overlap with LIN28. These were presumably stem cells localised in the medullar area of the gonad. In summary, we analysed for the first time spatial distribution of PGCs in fetal equine gonads. We demonstrated LIN28 to be a specific marker for PGCs also in the horse gonad, which is in agreement with the situation in human and other species. Furthermore, we identified stem cells and described their localization in the fetal equine gonad. Nevertheless, the temporal distribution of PGC and stem cells in the developing horse gonad and the role of LIN28 in the maintenance of the germline stem cell state still need to be investigated.

scholarly journals Three RNA Binding Proteins Form a Complex to Promote Differentiation of Germline Stem Cell Lineage in Drosophila

PLoS Genetics ◽  
2014 ◽  
Vol 10 (11) ◽  
pp. e1004797 ◽  
Author(s):  
Di Chen ◽  
Chan Wu ◽  
Shaowei Zhao ◽  
Qing Geng ◽  
Yu Gao ◽  
...  
Keyword(s):  
Stem Cell ◽  
Binding Proteins ◽  
Rna Binding ◽  
Rna Binding Proteins ◽  
Cell Lineage ◽  
Germline Stem Cell ◽  
Stem Cell Lineage

scholarly journals daf-16/FOXO blocks adult cell fate in Caenorhabditis elegans dauer larvae via lin-41/TRIM71

PLoS Genetics ◽  
2021 ◽  
Vol 17 (11) ◽  
pp. e1009881
Author(s):  
Matthew J. Wirick ◽  
Allison R. Cale ◽  
Isaac T. Smith ◽  
Amelia F. Alessi ◽  
Margaret R. Starostik ◽  
...  
Keyword(s):  
Stem Cells ◽  
Stem Cell ◽  
Cell Fate ◽  
Rna Binding ◽  
Cell Model ◽  
Cell Types ◽  
Adult Cell ◽  
Heterochronic Gene ◽  
Foxo Transcription Factors ◽  
Dauer Larvae

Many tissue-specific stem cells maintain the ability to produce multiple cell types during long periods of non-division, or quiescence. FOXO transcription factors promote quiescence and stem cell maintenance, but the mechanisms by which FOXO proteins promote multipotency during quiescence are still emerging. The single FOXO ortholog in C. elegans, daf-16, promotes entry into a quiescent and stress-resistant larval stage called dauer in response to adverse environmental cues. During dauer, stem and progenitor cells maintain or re-establish multipotency to allow normal development to resume after dauer. We find that during dauer, daf-16/FOXO prevents epidermal stem cells (seam cells) from prematurely adopting differentiated, adult characteristics. In particular, dauer larvae that lack daf-16 misexpress collagens that are normally adult-enriched. Using col-19p::gfp as an adult cell fate marker, we find that all major daf-16 isoforms contribute to opposing col-19p::gfp expression during dauer. By contrast, daf-16(0) larvae that undergo non-dauer development do not misexpress col-19p::gfp. Adult cell fate and the timing of col-19p::gfp expression are regulated by the heterochronic gene network, including lin-41 and lin-29. lin-41 encodes an RNA-binding protein orthologous to LIN41/TRIM71 in mammals, and lin-29 encodes a conserved zinc finger transcription factor. In non-dauer development, lin-41 opposes adult cell fate by inhibiting the translation of lin-29, which directly activates col-19 transcription and promotes adult cell fate. We find that during dauer, lin-41 blocks col-19p::gfp expression, but surprisingly, lin-29 is not required in this context. Additionally, daf-16 promotes the expression of lin-41 in dauer larvae. The col-19p::gfp misexpression phenotype observed in dauer larvae with reduced daf-16 requires the downregulation of lin-41, but does not require lin-29. Taken together, this work demonstrates a novel role for daf-16/FOXO as a heterochronic gene that promotes expression of lin-41/TRIM71 to contribute to multipotent cell fate in a quiescent stem cell model.

daf-16/FOXO blocks adult cell fate in Caenorhabditis elegans dauer larvae via lin-41/TRIM71

2021 ◽  
Author(s):  
Matthew J Wirick ◽  
Allison R Cale ◽  
Isaac T Smith ◽  
Amelia F Alessi ◽  
Margaret R Starostik ◽  
...  
Keyword(s):  
Stem Cells ◽  
Stem Cell ◽  
Cell Fate ◽  
Rna Binding ◽  
Cell Model ◽  
Cell Types ◽  
Adult Cell ◽  
Heterochronic Gene ◽  
Foxo Transcription Factors ◽  
Dauer Larvae

Many tissue-specific stem cells maintain the ability to produce multiple cell types during long periods of non-division, or quiescence. FOXO transcription factors promote quiescence and stem cell maintenance, but the mechanisms by which FOXO proteins promote multipotency during quiescence are still emerging. The single FOXO ortholog in C. elegans, daf-16, promotes entry into a quiescent and stress-resistant larval stage called dauer in response to adverse environmental cues. During dauer, stem and progenitor cells maintain or re-establish multipotency to allow normal development to resume after dauer. We find that during dauer, daf-16/FOXO prevents epidermal stem cells (seam cells) from prematurely adopting differentiated, adult characteristics. In particular, dauer larvae that lack daf-16 misexpress collagens that are normally adult-enriched. Using col-19p::gfp as an adult cell fate marker, we find that all major daf-16 isoforms contribute to opposing col-19p::gfp expression during dauer. By contrast, daf-16(0) larvae that undergo non-dauer development do not misexpress col-19p::gfp. Adult cell fate and the timing of col-19p::gfp expression are regulated by the heterochronic gene network, including lin-41 and lin-29. lin-41 encodes an RNA-binding protein orthologous to LIN41/TRIM71 in mammals, and lin-29 encodes a conserved zinc finger transcription factor. In non-dauer development lin-41 opposes adult cell fate by inhibiting the translation of lin-29, which directly activates col-19 transcription and promotes adult cell fate. We find that during dauer, lin-41 blocks col-19p::gfp expression, but surprisingly, lin-29 is not required in this context. Additionally, daf-16 promotes the expression of lin-41 in dauer larvae. The col-19p::gfp misexpression phenotype observed in dauer larvae with reduced daf-16 requires the downregulation of lin-41, but does not require lin-29. Taken together, this work demonstrates a novel role for daf-16/FOXO as a heterochronic gene that promotes expression of lin-41/TRIM71 to contribute to multipotent cell fate in a quiescent stem cell model.

scholarly journals Troy+ brain stem cells cycle through quiescence and regulate their number by sensing niche occupancy

2018 ◽  
Vol 115 (4) ◽  
pp. E610-E619 ◽  
Author(s):  
Onur Basak ◽  
Teresa G. Krieger ◽  
Mauro J. Muraro ◽  
Kay Wiebrands ◽  
Daniel E. Stange ◽  
...  
Keyword(s):  
Stem Cells ◽  
Stem Cell ◽  
Cell Number ◽  
Lineage Tracing ◽  
Rapid Expansion ◽  
Molecular Signature ◽  
Genetic Lineage ◽  
Proliferating Cells ◽  
Self Renewal ◽  
Genetic Lineage Tracing

The adult mouse subependymal zone provides a niche for mammalian neural stem cells (NSCs). However, the molecular signature, self-renewal potential, and fate behavior of NSCs remain poorly defined. Here we propose a model in which the fate of active NSCs is coupled to the total number of neighboring NSCs in a shared niche. Using knock-in reporter alleles and single-cell RNA sequencing, we show that the Wnt target Tnfrsf19/Troy identifies both active and quiescent NSCs. Quantitative analysis of genetic lineage tracing of individual NSCs under homeostasis or in response to injury reveals rapid expansion of stem-cell number before some return to quiescence. This behavior is best explained by stochastic fate decisions, where stem-cell number within a shared niche fluctuates over time. Fate mapping proliferating cells using a Ki67iresCreER allele confirms that active NSCs reversibly return to quiescence, achieving long-term self-renewal. Our findings suggest a niche-based mechanism for the regulation of NSC fate and number.

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