scholarly journals Hatched and starved: Two chromatin compaction mechanisms join forces to silence germ cell genome

2021 ◽  
Vol 220 (9) ◽  
Author(s):  
Ana Karina Morao ◽  
Sevinc Ercan
Keyword(s):  
Germ Cell ◽  
Germ Cells ◽  
Nutrient Availability ◽  
Food Shortage ◽  
Chromatin Compaction ◽  
C Elegans ◽  
Cell Genome

Animals evolved in environments with variable nutrient availability and one form of adaptation is the delay of reproduction in food shortage conditions. Belew et al. (2021. J. Cell Biol.https://doi.org/10.1083/jcb.202009197) report that in the nematode C. elegans, starvation-induced transcriptional quiescence in germ cells is achieved through a pathway that combines two well-known chromatin compaction mechanisms.

scholarly journals Genetic control of programmed cell death in the Caenorhabditis elegans hermaphrodite germline

Development ◽  
1999 ◽  
Vol 126 (5) ◽  
pp. 1011-1022 ◽  
Author(s):  
T.L. Gumienny ◽  
E. Lambie ◽  
E. Hartwieg ◽  
H.R. Horvitz ◽  
M.O. Hengartner
Keyword(s):  
Cell Death ◽  
Caenorhabditis Elegans ◽  
Germ Cell ◽  
Somatic Cell ◽  
Cell Fate ◽  
Germ Cells ◽  
Mapk Pathway ◽  
Apoptotic Cell ◽  
C Elegans ◽  
Pathway Activation

Development of the nematode Caenorhabditis elegans is highly reproducible and the fate of every somatic cell has been reported. We describe here a previously uncharacterized cell fate in C. elegans: we show that germ cells, which in hermaphrodites can differentiate into sperm and oocytes, also undergo apoptotic cell death. In adult hermaphrodites, over 300 germ cells die, using the same apoptotic execution machinery (ced-3, ced-4 and ced-9) as the previously described 131 somatic cell deaths. However, this machinery is activated by a distinct pathway, as loss of egl-1 function, which inhibits somatic cell death, does not affect germ cell apoptosis. Germ cell death requires ras/MAPK pathway activation and is used to maintain germline homeostasis. We suggest that apoptosis eliminates excess germ cells that acted as nurse cells to provide cytoplasmic components to maturing oocytes.

scholarly journals C. elegans Anillin proteins regulate intercellular bridge stability and germline syncytial organization

2014 ◽  
Vol 206 (1) ◽  
pp. 129-143 ◽  
Author(s):  
Rana Amini ◽  
Eugénie Goupil ◽  
Sara Labella ◽  
Monique Zetka ◽  
Amy S. Maddox ◽  
...  
Keyword(s):  
Caenorhabditis Elegans ◽  
Germ Cell ◽  
Germ Cells ◽  
Cytoplasmic Streaming ◽  
Intercellular Bridge ◽  
Cell Specification ◽  
Intercellular Bridges ◽  
C Elegans ◽  
Daughter Cells ◽  
Germ Cell Specification

Cytokinesis generally produces two separate daughter cells, but in some tissues daughter nuclei remain connected to a shared cytoplasm, or syncytium, through incomplete cytokinesis. How syncytia form remains poorly understood. We studied syncytial formation in the Caenorhabditis elegans germline, in which germ cells connect to a shared cytoplasm core (the rachis) via intercellular bridges. We found that syncytial architecture initiates early in larval development, and germ cells become progressively interconnected until adulthood. The short Anillin family scaffold protein ANI-2 is enriched at intercellular bridges from the onset of germ cell specification, and ANI-2 loss resulted in destabilization of intercellular bridges and germ cell multinucleation defects. These defects were partially rescued by depleting the canonical Anillin ANI-1 or blocking cytoplasmic streaming. ANI-2 is also required for elastic deformation of the gonad during ovulation. We propose that ANI-2 promotes germ cell syncytial organization and allows for compensation of the mechanical stress associated with oogenesis by conferring stability and elasticity to germ cell intercellular bridges.

scholarly journals The C. elegans gonadal sheath Sh1 cells associate selectively with a differentiating germ cell population in the proliferative zone

2021 ◽  
Author(s):  
Xin Li ◽  
Noor Singh ◽  
Camille Miller ◽  
India Washington ◽  
Bintou Sosseh ◽  
...  
Keyword(s):  
Germ Cell ◽  
Germ Cells ◽  
Germ Line ◽  
Fluorescent Proteins ◽  
Temperature Sensitive ◽  
Variable Expression ◽  
C Elegans ◽  
Proliferative Zone ◽  
Adult Hermaphrodite ◽  
Sheath Cells

The C. elegans adult hermaphrodite germ line is surrounded by a thin tube formed by somatic sheath cells that support germ cells as they mature from the stem-like mitotic state through meiosis, gametogenesis and ovulation. Recently, we discovered that the distal-most Sh1 sheath cells associate with mitotic germ cells as they exit the niche. Here we report that these distal sheath-associated germ cells differentiate first in animals with temperature-sensitive mutations affecting germ cell state, and stem-like germ cells are maintained distal to the Sh1 boundary. We analyze several markers of the distal sheath, which is best visualized with endogenously tagged membrane proteins, as overexpressed fluorescent proteins fail to localize to distal membrane processes and can cause gonad morphology defects. However, such reagents with highly variable expression can be used to determine the relative positions of the two Sh1 cells, one of which often extends further distal than the other.

scholarly journals Protection of the C. elegans germ cell genome depends on diverse DNA repair pathways during normal proliferation

PLoS ONE ◽  
2021 ◽  
Vol 16 (4) ◽  
pp. e0250291
Author(s):  
Bettina Meier ◽  
Nadezda V. Volkova ◽  
Ye Hong ◽  
Simone Bertolini ◽  
Víctor González-Huici ◽  
...  
Keyword(s):  
Dna Repair ◽  
Germ Cell ◽  
Excision Repair ◽  
Base Substitution ◽  
Structural Variants ◽  
C Elegans ◽  
Repair Deficiency ◽  
Repair Pathways ◽  
Cell Genome ◽  
Dna Repair Mutants

Maintaining genome integrity is particularly important in germ cells to ensure faithful transmission of genetic information across generations. Here we systematically describe germ cell mutagenesis in wild-type and 61 DNA repair mutants cultivated over multiple generations. ~44% of the DNA repair mutants analysed showed a >2-fold increased mutagenesis with a broad spectrum of mutational outcomes. Nucleotide excision repair deficiency led to higher base substitution rates, whereaspolh-1(Polη) andrev-3(Polζ) translesion synthesis polymerase mutants resulted in 50–400 bp deletions. Signatures associated with defective homologous recombination fall into two classes: 1)brc-1/BRCA1andrad-51/RAD51 paralog mutants showed increased mutations across all mutation classes, 2)mus-81/MUS81andslx-1/SLX1nuclease, andhim-6/BLM,helq-1/HELQorrtel-1/RTEL1helicase mutants primarily accumulated structural variants. Repetitive and G-quadruplex sequence-containing loci were more frequently mutated in specific DNA repair backgrounds. Tandem duplications embedded in inverted repeats were observed inhelq-1helicase mutants, and a unique pattern of ‘translocations’ involving homeologous sequences occurred inrip-1recombination mutants.atm-1/ATM checkpoint mutants harboured structural variants specifically enriched in subtelomeric regions. Interestingly, locally clustered mutagenesis was only observed for combinedbrc-1andcep-1/p53 deficiency. Our study provides a global view of how different DNA repair pathways contribute to prevent germ cell mutagenesis.

scholarly journals Functional Recovery of the Germ Line Following Splicing Collapse

2021 ◽  
Author(s):  
Wei Cao ◽  
Christopher Tran ◽  
Stuart K Archer ◽  
Sandeep Gopal ◽  
Roger Pocock
Keyword(s):  
Germ Cell ◽  
Germ Cells ◽  
Rna Splicing ◽  
Messenger Rna ◽  
Germ Line ◽  
Intron Retention ◽  
Mrna Splicing ◽  
C Elegans ◽  
Mrna Transcripts ◽  
Line Following

Splicing introns from precursor-messenger RNA (pre-mRNA) transcripts is essential for translating functional proteins. Here, we report that the previously uncharacterized Caenorhabditis elegans protein MOG-7, acts as a pre-mRNA splicing factor. Depleting MOG-7 from the C. elegans germ line causes intron retention in the majority of germline-expressed genes, impeding the germ cell cycle, and causing defects in nuclear morphology, germ cell identity and sterility. Despite the deleterious consequences caused by MOG-7 loss, the adult germ line can functionally recover to produce viable and fertile progeny when MOG-7 is restored. Germline recovery is dependent on a burst of apoptosis that likely clears defective germ cells, and viable gametes generated from the proliferation of germ cells in the progenitor zone. Together, these findings reveal that MOG-7 is essential for germ cell development, and that the germ line is able to functionally recover after a collapse in RNA splicing.

scholarly journals Positive mRNA Translational Control in Germ Cells by Initiation Factor Selectivity

2015 ◽  
Vol 2015 ◽  
pp. 1-11 ◽  
Author(s):  
Andrew J. Friday ◽  
Brett D. Keiper
Keyword(s):  
Germ Cell ◽  
Germ Cells ◽  
Translation Initiation ◽  
Translational Control ◽  
Rna Binding ◽  
Rna Binding Proteins ◽  
Positive Function ◽  
Initiation Factor ◽  
C Elegans ◽  
Initiation Factors

Ultimately, the production of new proteins in undetermined cells pushes them to new fates. Other proteins hold a stem cell in a mode of self-renewal. In germ cells, these decision-making proteins are produced largely from translational control of preexisting mRNAs. To date, all of the regulation has been attributed to RNA binding proteins (RBPs) that repress mRNAs in many models of germ cell development (Drosophila, mouse,C. elegans, andXenopus). In this review, we focus on the selective, positive function of translation initiation factors eIF4E and eIF4G, which recruit mRNAs to ribosomes upon derepression. Evidence now shows that the two events are not separate but rather are coordinated through composite complexes of repressors and germ cell isoforms of eIF4 factors. Strikingly, the initiation factor isoforms are themselves mRNA selective. The mRNP complexes of translation factors and RBPs are built on specific populations of mRNAs to prime them for subsequent translation initiation. Simple rearrangement of the partners causes a dormant mRNP to become synthetically active in germ cells when and where they are required to support gametogenesis.

scholarly journals Delay in primordial germ cell migration in adamts9 knockout zebrafish

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Jonathan J. Carver ◽  
Yuanfa He ◽  
Yong Zhu
Keyword(s):  
Cell Migration ◽  
Germ Cell ◽  
Germ Cells ◽  
Primordial Germ Cells ◽  
Primordial Germ Cell ◽  
Ring Stage ◽  
C Elegans ◽  
Germ Cell Migration ◽  
A Disintegrin And Metalloproteinase

AbstractAdamts9 (a disintegrin and metalloproteinase with a thrombospondin type 1 motif, member 9) is one of a few metalloproteinases structurally conserved from C. elegans to humans and is indispensable in germ cell migration in invertebrates. However, adamts9′s roles in germ cell migration in vertebrates has not been examined. In the present study, we found zygotic expression of adamts9 started around the germ ring stage and reached peak levels at 3 days post fertilization (dpf) in zebrafish. The migration of primordial germ cells (PGC) was completed within 24 hours (h) in wildtype siblings, while a delay in PGC migration was found at 15 and 24-h post-fertilization (hpf) in the Adamts9 knockout (KO). However, the delayed PGC migration in Adamts9 KO disappeared at 48 hpf. Our study suggests a conserved function of Adamts9 in germ cell migration among invertebrates and vertebrates. In addition, our results also suggest that Adamts9 is not essential for germ cell migration as reported in C. elegans, possibly due to expansion of Adamts family members and compensatory roles from other metalloproteinases in vertebrates. Further studies are required in order to elucidate the functions and mechanisms of metalloproteinases in germ cell migration and gonad formation in vertebrates.

scholarly journals Conversion of Germ Cells to Somatic Cell Types in C. elegans

2020 ◽  
Vol 8 (4) ◽  
pp. 24 ◽  
Author(s):  
Nida ul Fatima ◽  
Baris Tursun
Keyword(s):  
Transcription Factor ◽  
Germ Cell ◽  
Somatic Cell ◽  
Cell Fate ◽  
Germ Cells ◽  
Molecular Mechanisms ◽  
Essential Property ◽  
C Elegans ◽  
Differentiated Cells ◽  
A Cell

The potential of a cell to produce all types of differentiated cells in an organism is termed totipotency. Totipotency is an essential property of germ cells, which constitute the germline and pass on the parental genetic material to the progeny. The potential of germ cells to give rise to a whole organism has been the subject of intense research for decades and remains important in order to better understand the molecular mechanisms underlying totipotency. A better understanding of the principles of totipotency in germ cells could also help to generate this potential in somatic cell lineages. Strategies such as transcription factor-mediated reprogramming of differentiated cells to stem cell-like states could benefit from this knowledge. Ensuring pluripotency or even totipotency of reprogrammed stem cells are critical improvements for future regenerative medicine applications. The C. elegans germline provides a unique possibility to study molecular mechanisms that maintain totipotency and the germ cell fate with its unique property of giving rise to meiotic cells Studies that focused on these aspects led to the identification of prominent chromatin-repressing factors such as the C. elegans members of the Polycomb Repressive Complex 2 (PRC2). In this review, we summarize different factors that were recently identified, which use molecular mechanisms such as control of protein translation or chromatin repression to ensure maintenance of totipotency and the germline fate. Additionally, we focus on recently identified factors involved in preventing transcription-factor-mediated conversion of germ cells to somatic lineages. These so-called reprogramming barriers have been shown in some instances to be conserved with regard to their function as a cell fate safeguarding factor in mammals. Overall, continued studies assessing the different aspects of molecular pathways involved in maintaining the germ cell fate in C. elegans may provide more insight into cell fate safeguarding mechanisms also in other species.

scholarly journals Deficiency for Piwi results in transmission of a heritable stress that promotes longevity via DAF-16/Foxo

2018 ◽  
Author(s):  
Bree Heestand ◽  
Matt Simon ◽  
Stephen Frenk ◽  
Shawn Ahmed
Keyword(s):  
Germ Cell ◽  
Germ Cells ◽  
Stress Resistance ◽  
Rnai Pathway ◽  
Early Generation ◽  
C Elegans ◽  
Systemic Rnai ◽  
Late Generation ◽  
Cell Immortality ◽  
F1 Cross

AbstractThe C. elegans Piwi Argonaute protein PRG-1 and associated piRNAs protect the genomes of germ cells by suppressing the expression of transposons and potentially deleterious foreign nucleic acids. Deficiency for prg-1 compromises germ cell immortality, resulting in normal fertility for many generations followed by progressively reduced fertility and ultimately sterility. The sterility phenotype of prg-1 mutants was recently shown to be a form of reproductive arrest, which implies that prg-1 mutants may become sterile in response to a form of heritable stress. The DAF-16 stress resistance and longevity factor can promote germ cell immortality of prg-1 mutants by activating a systemic RNAi pathway. We found that this RNAi pathway was not required for the somatic longevity function of DAF-16. Given that prg-1 mutant germ cells may transmit a form of heritable stress, we studied the somatic longevity of prg-1 mutant adults. We found that early generation prg-1 mutants had normal lifespans, but that late-generation adults that displayed reduced fertility or sterility were long lived. Germ cells of long-lived late-generation prg-1 mutants gave rise to F1 cross progeny that were heterozygous for prg-1, fertile and also long lived. However, in the absence of DAF-16, the heritable stress transmitted by prg-1 mutant germ cells was deleterious and caused lifespan to shorten. We conclude that deficiency for the genomic surveillance factor PRG-1/Piwi results in germ cells that transmit a heritable stress that promotes somatic longevity via DAF-16/Foxo, which could be relevant transgenerational regulationof aging.

scholarly journals Multi-modal regulation of C. elegans hermaphrodite spermatogenesis by the GLD-1-FOG-2 complex

2018 ◽  
Author(s):  
Shuang Hu ◽  
Lauren E. Ryan ◽  
Ebru Kaymak ◽  
Lindsay Freeberg ◽  
Te-Wen Lo ◽  
...  
Keyword(s):  
Sex Determination ◽  
Germ Cell ◽  
Germ Cells ◽  
Translational Control ◽  
Rna Binding ◽  
Rna Binding Proteins ◽  
Wild Type ◽  
C Elegans ◽  
Target Mrnas ◽  
Mrna Targets

AbstractProper germ cell sex determination in Caenorhabditis nematodes requires a network of RNA-binding proteins (RBPs) and their target mRNAs. In some species, changes in this network enabled limited XX spermatogenesis, and thus self-fertility. In C. elegans, one of these selfing species, the global sex-determining gene tra-2 is regulated in germ cells by a conserved RBP, GLD-1, via the 3’ untranslated region (3’UTR) of its transcript. A C. elegans-specific GLD-1 cofactor, FOG-2, is also required for hermaphrodite sperm fate, but how it modifies GLD-1 function is unknown. Germline feminization in gld-1 and fog-2 null mutants has been interpreted as due to cell-autonomous elevation of TRA-2 translation. Consistent with the proposed role of FOG-2 in translational control, the abundance of nearly all GLD-1 target mRNAs (including tra-2) is unchanged in fog-2 mutants. Epitope tagging reveals abundant TRA-2 expression in somatic tissues, but an undetectably low level in wild-type germ cells. Loss of gld-1 function elevates germline TRA-2 expression to detectable levels, but loss of fog-2 function does not. A simple quantitative model of tra-2 activity constrained by these results can successfully sort genotypes into normal or feminized groups. Surprisingly, fog-2 and gld-1 activity enable the sperm fate even when GLD-1 cannot bind to the tra-2 3’ UTR. This suggests the GLD-1-FOG-2 complex regulates uncharacterized sites within tra-2, or other mRNA targets. Finally, we quantify the RNA-binding capacities of dominant missense alleles of GLD-1 that act genetically as “hyperrepressors” of tra-2 activity. These variants bind RNA more weakly in vitro than does wild-type GLD-1. These results indicate that gld-1 and fog-2 regulate germline sex via multiple interactions, and that our understanding of the control and evolution of germ cell sex determination in the C. elegans hermaphrodite is far from complete.

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