scholarly journals A PUF hub drives self-renewal in C. elegans germline stem cells

2019 ◽  
Author(s):  
Kimberly A. Haupt ◽  
Kimberley T. Law ◽  
Amy L. Enright ◽  
Charlotte R. Kanzler ◽  
Heaji Shin ◽  
...  
Keyword(s):  
Stem Cells ◽  
Stem Cell ◽  
Notch Signaling ◽  
Rna Binding ◽  
Rna Binding Proteins ◽  
Germline Stem Cells ◽  
Null Mutant ◽  
Self Renewal ◽  
Puf Proteins ◽  
C Elegans

ABSTRACTStem cell regulation relies on extrinsic signaling from a niche plus intrinsic factors that respond and drive self-renewal within stem cells. A priori, loss of niche signaling and loss of the intrinsic self-renewal factors might be expected to have equivalent stem cell defects. Yet this simple prediction has not been borne out for most stem cells, including C. elegans germline stem cells (GSCs). The central regulators of C. elegans GSCs include extrinsically-acting GLP-1/Notch signaling from the niche, intrinsically-acting RNA binding proteins in the PUF family, termed FBF-1 and FBF-2 (collectively FBF), and intrinsically-acting PUF partner proteins that are direct Notch targets. Abrogation of either GLP-1/Notch signaling or its targets yields an earlier and more severe GSC defect than loss of FBF-1 and FBF-2, suggesting that additional intrinsic regulators must exist. Here, we report that those missing regulators are two additional PUF proteins, PUF-3 and PUF-11. Remarkably, an fbf-1 fbf-2; puf-3 puf-11 quadruple null mutant has a GSC defect virtually identical to that of a glp-1/Notch null mutant. PUF-3 and PUF-11 both affect GSC maintenance; both are expressed in GSCs; and epistasis experiments place them at the same position as FBF within the network. Therefore, action of PUF-3 and PUF-11 explains the milder GSC defect in fbf-1 fbf-2 mutants. We conclude that a “PUF hub”, comprising four PUF proteins and two PUF partners, constitutes the intrinsic self-renewal node of the C. elegans GSC RNA regulatory network. Discovery of this hub underscores the significance of PUF RNA-binding proteins as key regulators of stem cell maintenance.

scholarly journals Regulation of the mitosis/meiosis decision in the Caenorhabditis elegans germline

2003 ◽  
Vol 358 (1436) ◽  
pp. 1359-1362 ◽  
Author(s):  
Sarah L. Crittenden ◽  
Christian R. Eckmann ◽  
Liaoteng Wang ◽  
David S. Bernstein ◽  
Marvin Wickens ◽  
...  
Keyword(s):  
Stem Cells ◽  
Caenorhabditis Elegans ◽  
Rna Binding ◽  
Rna Binding Proteins ◽  
Germline Stem Cells ◽  
Puf Proteins ◽  
C Elegans ◽  
Transcriptional Regulatory ◽  
Mitotic Proliferation ◽  
Multicellular Organisms

During the development of multicellular organisms, the processes of growth and differentiation are kept in balance to generate and maintain tissues and organs of the correct size, shape and cellular composition. We have investigated the molecular controls of growth and differentiation in the Caenorhabditis elegans germline. A single somatic cell, called the distal tip cell, promotes mitotic proliferation in the adjacent germline by GLP–1/Notch signalling. Within the germline, the decisions between mitosis and meiosis and between spermatogenesis and oogenesis are controlled by a group of conserved RNA regulators. FBF, a member of the PUF (for Pumilio and FBF) family of RNA–binding proteins, promotes mitosis by repressing gld–1 mRNA activity; the GLD–1, GLD–2, GLD–3 and NOS–3 proteins promote entry into meiosis by regulating mRNAs that remain unknown. The regulatory balance between opposing FBF and GLD activities is crucial for controlling the extent of germline proliferation. PUF proteins regulate germline stem cells in both Drosophila and C. elegans and are localized to germline stem cells of the mammalian testis. Therefore, this post–transcriptional regulatory switch may be an ancient mechanism for controlling maintenance of stem cells versus differentiation.

A sensitized genetic screen to identify regulators of C. elegans germline stem cells

2021 ◽  
Author(s):  
Sarah Robinson-Thiewes ◽  
Aaron M. Kershner ◽  
Heaji Shin ◽  
Kimberly A. Haupt ◽  
Peggy Kroll-Connor ◽  
...  
Keyword(s):  
Stem Cells ◽  
Rna Binding ◽  
Rna Binding Proteins ◽  
Gene Products ◽  
Germline Stem Cells ◽  
Loss Of Function ◽  
Genetic Screens ◽  
Self Renewal ◽  
C Elegans ◽  
Forward Genetic Screens

AbstractGermline stem cells (GSCs) in Caenorhabditis elegans are maintained by GLP-1/Notch signaling from the niche and by a downstream RNA regulatory network. Loss of the GLP-1 receptor causes GSCs to precociously undergo meiotic differentiation, the “Glp” phenotype, due to a failure to self-renew. lst-1 and sygl-1 are functionally redundant direct targets of GLP-1 signaling whose gene products work with PUF RNA binding proteins to promote GSC self-renewal. Whereas single loss-of-function mutants are fertile, lst-1 sygl-1 double mutants are sterile and Glp. We set out to identify genes that function redundantly with either lst-1 or sygl-1 to maintain GSCs. To this end, we conducted forward genetic screens for Glp mutants in genetic backgrounds lacking functional copies of either lst-1 or sygl-1. The screens generated nine glp-1 alleles, two lst-1 alleles, and one allele of pole-1, which encodes the catalytic subunit of DNA polymerase ε. Three glp-1 alleles reside in Ankyrin (ANK) repeats not previously mutated. pole-1 single mutants have a low penetrance Glp that is enhanced by loss of either lst-1 or sygl-1. Thus, the screen uncovered one locus that interacts genetically with both lst-1 and sygl-1 and generated useful mutations for further studies of GSC regulation.

scholarly journals Towards identifying subnetworks from FBF binding landscapes in Caenorhabditis spermatogenic or oogenic germlines

2018 ◽  
Author(s):  
Douglas F. Porter ◽  
Aman Prasad ◽  
Brian H. Carrick ◽  
Peggy Kroll-Connor ◽  
Marvin Wickens ◽  
...  
Keyword(s):  
Stem Cells ◽  
Stem Cell ◽  
Binding Proteins ◽  
Rna Binding ◽  
Rna Binding Proteins ◽  
Cell Cycle Regulators ◽  
Germline Stem Cells ◽  
Stem Cell Regulation ◽  
Cell Functions ◽  
Almost All

AbstractMetazoan PUF (Pumilio and FBF) RNA-binding proteins regulate various biological processes, but a common theme across phylogeny is stem cell regulation. In Caenorhabditis elegans, FBF (fem-3 Binding Factor) maintains germline stem cells regardless of which gamete is made, but FBF also functions in the process of spermatogenesis. We have begun to “disentangle” these biological roles by asking which FBF targets are gamete-independent, as expected for stem cells, and which are gamete-specific. Specifically, we compared FBF iCLIP binding profiles in adults making sperm to those making oocytes. Normally, XX adults make oocytes. To generate XX adults making sperm, we used a fem-3(gf) mutant requiring growth at 25°; for comparison, wild-type oogenic hermaphrodites were also raised at 25°. Our FBF iCLIP data revealed FBF binding sites in 1522 RNAs from oogenic adults and 1704 RNAs from spermatogenic adults. More than half of these FBF targets were independent of germline gender. We next clustered RNAs by FBF-RNA complex frequencies and found four distinct blocks. Block I RNAs were enriched in spermatogenic germlines, and included validated target fog-3, while Block II and III RNAs were common to both genders, and Block IV RNAs were enriched in oogenic germlines. Block II (510 RNAs) included almost all validated FBF targets and was enriched for cell cycle regulators. Block III (21 RNAs) was enriched for RNA-binding proteins, including previously validated FBF targets gld-1 and htp-1. We suggest that Block I RNAs belong to the FBF network for spermatogenesis, and that Blocks II and III are associated with stem cell functions.

scholarly journals Centrosome misorientation mediates slowing of the cell cycle under limited nutrient conditions in Drosophila male germline stem cells

2012 ◽  
Vol 23 (8) ◽  
pp. 1524-1532 ◽  
Author(s):  
Therese M. Roth ◽  
C.-Y. Ason Chiang ◽  
Mayu Inaba ◽  
Hebao Yuan ◽  
Viktoria Salzmann ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Stem Cells ◽  
Cell Proliferation ◽  
Stem Cell ◽  
Germline Stem Cells ◽  
Self Renewal ◽  
Stem Cell Regulation ◽  
Male Germline ◽  
Male Germline Stem Cells ◽  
Nutrient Conditions

Drosophila male germline stem cells (GSCs) divide asymmetrically, balancing self-renewal and differentiation. Although asymmetric stem cell division balances between self-renewal and differentiation, it does not dictate how frequently differentiating cells must be produced. In male GSCs, asymmetric GSC division is achieved by stereotyped positioning of the centrosome with respect to the stem cell niche. Recently we showed that the centrosome orientation checkpoint monitors the correct centrosome orientation to ensure an asymmetric outcome of the GSC division. When GSC centrosomes are not correctly oriented with respect to the niche, GSC cell cycle is arrested/delayed until the correct centrosome orientation is reacquired. Here we show that induction of centrosome misorientation upon culture in poor nutrient conditions mediates slowing of GSC cell proliferation via activation of the centrosome orientation checkpoint. Consistently, inactivation of the centrosome orientation checkpoint leads to lack of cell cycle slowdown even under poor nutrient conditions. We propose that centrosome misorientation serves as a mediator that transduces nutrient information into stem cell proliferation, providing a previously unappreciated mechanism of stem cell regulation in response to nutrient conditions.

scholarly journals The Expression of Markers Related to Ovarian Germline Stem Cells in the Mouse Ovarian Surface Epithelium and the Correlation with Notch Signaling Pathway

2015 ◽  
Vol 37 (6) ◽  
pp. 2311-2322 ◽  
Author(s):  
Zezheng Pan ◽  
Mengli Sun ◽  
Jia Li ◽  
Fangyue Zhou ◽  
Xia Liang ◽  
...  
Keyword(s):  
Stem Cells ◽  
Stem Cell ◽  
Notch Signaling ◽  
Signaling Pathway ◽  
Ovarian Surface Epithelium ◽  
Notch Signaling Pathway ◽  
Surface Epithelium ◽  
Stem Cell Markers ◽  
Germline Stem Cells ◽  
Ovarian Surface

Background/Aims: Ovarian germline stem cells (OGSCs) have been shown to mainly exist in the ovarian surface epithelium (OSE), but the activity changes of germline stem cells during different reproductive stages and the potential regulatory signaling pathway are still unknown. The Notch signaling pathway plays a key role in cell development, primordial follicles and stem cell proliferation. However, whether it plays a role in the proliferation of OGSCs is unknown. Here, we analyzed the activity changes of germline stem cells and the correlation between germline stem cells and the Notch signaling pathway. Methods: The expression of germline stem cell markers Mvh, Ooc4 and the Notch molecules Notch1, Hes1, and Hes5 were detected during 3 days (3d), and 2, 12, 20 months (2m, 12m, 20m) mouse ovarian surface epithelium samples. DAPT, a specific inhibitor of the Notch pathway, was used to observe the influence of Notch signaling in the germline stem cells. Results: The results showed that the levels of MVH and OCT4 decreased substantially with reproductive age in ovarian surface epithelium, and the same tendency was detected in the Notch signaling molecules Notch1, Hes1 and Hes5. Dual-IF results showed that the germline stem cell markers were co-expressed with Notch molecules in the ovarian surface epithelium. While, the expression of MVH and OCT4 were reduced when the ovaries were treated with DAPT and the levels were attenuated with increasing dose of DAPT. Conclusion: Taken together, our results indicate that the viability of OGSCs decreased with the age of the mouse ovaries, and the activity of OGSCs in the ovarian surface epithelium may be related to the Notch signaling pathway.

scholarly journals C. elegans germ cells divide and differentiate along a folded epithelium

2018 ◽  
Author(s):  
Hannah S. Seidel ◽  
Tilmira A. Smith ◽  
Jessica K. Evans ◽  
Jarred Q. Stamper ◽  
Thomas G. Mast ◽  
...  
Keyword(s):  
Stem Cells ◽  
Stem Cell ◽  
Germ Cells ◽  
Cell Model ◽  
Three Dimensional ◽  
3D Models ◽  
Germline Stem Cells ◽  
C Elegans ◽  
Stem Cell Regulation ◽  
Stem Cell Model

AbstractKnowing how stem cells and their progeny are positioned within their tissues is essential for understanding their regulation. One paradigm for stem cell regulation is the C. elegans germline, which is maintained by a pool of germline stem cells in the distal gonad, in a region known as the ‘progenitor zone’. The C. elegans germline is widely used as a stem cell model, but the cellular architecture of the progenitor zone has been unclear. Here we characterize this architecture by creating virtual 3D models of the progenitor zone in both sexes. We show that the progenitor zone in adult hermaphrodites is essentially a folded epithelium. The progenitor zone in males is not folded. Analysis of germ cell division shows that daughter cells are born side-by-side along the surface of the epithelium. Analysis of a key regulator driving differentiation, GLD-1, shows that germ cells in hermaphrodites differentiate along the path of the folded epithelium, with previously described “steps” in GLD-1 expression corresponding to germline folds. Our study provides a three-dimensional view of how C. elegans germ cells progress from stem cell to overt differentiation, with critical implications for regulators driving this transition.

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.

Sign in / Sign up

Export Citation Format

Share Document