scholarly journals Anillin proteins stabilize the cytoplasmic bridge between the two primordial germ cells during C. elegans embryogenesis

2017 ◽  
Author(s):  
Eugénie Goupil ◽  
Rana Amini ◽  
Jean-Claude Labbé
Keyword(s):  
Germ Line ◽  
Primordial Germ Cells ◽  
Primordial Germ Cell ◽  
Cytoplasmic Bridge ◽  
C Elegans ◽  
Daughter Cells ◽  
Cytoplasmic Bridges ◽  
Key Steps ◽  
Muscle Myosin

ABSTRACTStable cytoplasmic bridges arise from failed cytokinesis, the last step of cell division, and are a key feature of syncytial architectures in the germ line of most metazoans. Whereas the C. elegans germ line is syncytial, its formation remains poorly understood. We studied the role of ANI-2, a noncanonical and shorter form of the actomyosin scaffold protein anillin that is expressed specifically during embryogenesis in the germ line precursor blastomere, P4. We found that the P4 blastomere does not complete abscission following cytokinesis, leaving a stable cytoplasmic bridge between the two daughter cells. Interestingly, depletion of ANI-2 results in a regression of the membrane partition between the two cells, indicating that ANI-2 is required to stabilize the cytoplasmic bridge. We identified several contractility regulators that, like ANI-2, localize to the cytoplasmic bridge and are required to stabilize it. Epistatic analysis of these regulators’ mutual dependencies revealed a pathway in which Rho regulators promote ANI-2 accumulation at the stable cytoplasmic bridge, which in turns promotes the accumulation of the non-muscle myosin II NMY-2 and the midbody component CYK-7 at the bridge, in part by limiting the accumulation of canonical anillin ANI-1. Our results uncover key steps in C. elegans germ line formation and define a set of conserved regulators that ensure the proper stability of the primordial germ cell cytoplasmic bridge during embryonic development.

scholarly journals Actomyosin contractility regulators stabilize the cytoplasmic bridge between the two primordial germ cells during Caenorhabditis elegans embryogenesis

2017 ◽  
Vol 28 (26) ◽  
pp. 3789-3800 ◽  
Author(s):  
Eugénie Goupil ◽  
Rana Amini ◽  
David H. Hall ◽  
Jean-Claude Labbé
Keyword(s):  
Caenorhabditis Elegans ◽  
Primordial Germ Cells ◽  
Primordial Germ Cell ◽  
Cytoplasmic Bridge ◽  
C Elegans ◽  
Daughter Cells ◽  
Actomyosin Contractility ◽  
Nonmuscle Myosin Ii ◽  
Cytoplasmic Bridges ◽  
Key Steps

Stable cytoplasmic bridges arise from failed cytokinesis, the last step of cell division, and are a key feature of syncytial architectures in the germline of most metazoans. Whereas the Caenorhabditis elegans germline is syncytial, its formation remains poorly understood. We found that the germline precursor blastomere, P4, fails cytokinesis, leaving a stable cytoplasmic bridge between the two daughter cells, Z2 and Z3. Depletion of several regulators of actomyosin contractility resulted in a regression of the membrane partition between Z2 and Z3, indicating that they are required to stabilize the cytoplasmic bridge. Epistatic analysis revealed a pathway in which Rho regulators promote accumulation of the noncannonical anillin ANI-2 at the stable cytoplasmic bridge, which in turns promotes the accumulation of the nonmuscle myosin II NMY-2 and the midbody component CYK-7 at the bridge, in part by limiting the accumulation of canonical anillin ANI-1. Our results uncover key steps in C. elegans germline formation and define a set of conserved regulators that are enriched at the primordial germ cell cytoplasmic bridge to ensure its stability during embryonic development.

scholarly journals DAF-18/PTEN inhibits germline zygotic gene activation during primordial germ cell quiescence

2020 ◽  
Author(s):  
Amanda L. Fry ◽  
Amy Webster ◽  
Rojin Chitrakar ◽  
L. Ryan Baugh ◽  
E. Jane Albert Hubbard
Keyword(s):  
Cell Cycle ◽  
Germ Line ◽  
Primordial Germ Cells ◽  
Primordial Germ Cell ◽  
Gene Activation ◽  
Dependent Manner ◽  
Germline Gene ◽  
C Elegans ◽  
Zygotic Gene ◽  
Zygotic Gene Activation

AbstractQuiescence, an actively-maintained reversible state of cell cycle arrest, is not well understood. PTEN is one of the most frequently lost tumor suppressors in human cancers and regulates quiescence of stem cells and cancer cells. In C. elegans mutant for daf-18, the sole C. elegans PTEN ortholog, primordial germ cells (PGCs) divide inappropriately in starvation conditions, in a TOR-dependent manner. Here, we further investigated the role of daf-18 in maintaining PGC quiescence. We found that maternal or zygotic daf-18 is sufficient to maintain cell cycle quiescence, that daf-18 acts in the germ line and soma, and that daf-18 affects timing of PGC divisions in fed animals. Importantly, our results also implicate daf-18 in zygotic germline gene activation, though not in germline fate specification. However, TOR is less important to zygotic germline gene expression, suggesting that in the absence of food daf-18/PTEN prevents inappropriate germline zygotic gene activation and cell division by distinct mechanisms.

Transformation of the germ line into muscle in mes-1 mutant embryos of C. elegans

Development ◽  
1995 ◽  
Vol 121 (9) ◽  
pp. 2961-2972 ◽  
Author(s):  
S. Strome ◽  
P. Martin ◽  
E. Schierenberg ◽  
J. Paulsen
Keyword(s):  
Cell Fate ◽  
Germ Cells ◽  
Germ Line ◽  
Primordial Germ Cells ◽  
Primordial Germ Cell ◽  
Wild Type ◽  
C Elegans ◽  
Stem Cell Divisions ◽  
Asymmetric Partitioning

Mutations in the maternal-effect sterile gene mes-1 cause the offspring of homozygous mutant mothers to develop into sterile adults. Lineage analysis revealed that mutant offspring are sterile because they fail to form primordial germ cells during embryogenesis. In wild-type embryos, the primordial germ cell P4 is generated via a series of four unequal stem-cell divisions of the zygote. mes-1 embryos display a premature and progressive loss of polarity in these divisions: P0 and P1 undergo apparently normal unequal divisions and cytoplasmic partitioning, but P2 (in some embryos) and P3 (in most embryos) display defects in cleavage asymmetry and fail to partition lineage-specific components to only one daughter cell. As an apparent consequence of these defects, P4 is transformed into a muscle precursor, like its somatic sister cell D, and generates up to 20 body muscle cells instead of germ cells. Our results show that the wild-type mes-1 gene participates in promoting unequal germ-line divisions and asymmetric partitioning events and thus the determination of cell fate in early C. elegans embryos.

AMPK blocks chromatin activation and consequent R-loop formation to protect genome stability following acute starvation

2021 ◽  
Author(s):  
Bing Sun ◽  
McLean Sherrin ◽  
Richard Roy
Keyword(s):  
Dna Damage ◽  
Genome Stability ◽  
Germ Line ◽  
Critical Role ◽  
Significant Proportion ◽  
Loop Formation ◽  
C Elegans ◽  
Chromatin Activation ◽  
Acute Starvation

Abstract During periods of starvation organisms must modify both gene expression and metabolic pathways to adjust to the energy stress. We previously reported that C. elegans that lack AMPK have transgenerational reproductive defects that result from abnormally elevated H3K4me3 levels in the germ line following recovery from acute starvation1. Here we show that H3K4me3 is dramatically increased at promoters, driving aberrant transcription elongation that results in the accumulation of R-loops in the starved AMPK mutants. DRIP-seq analysis demonstrated that a significant proportion of the genome was affected by R-loop formation with a dramatic expansion in the number of R-loops at numerous loci, most pronounced at the promoter-TSS regions of genes in the starved AMPK mutants. The R-loops are transmissible into subsequent generations, likely contributing to the transgenerational reproductive defects typical of these mutants following starvation. Strikingly, AMPK null germ lines show considerably more RAD-51 foci at sites of R-loop formation, potentially sequestering it from its critical role at meiotic breaks and/or at sites of induced DNA damage. Our study reveals a previously unforeseen role of AMPK in maintaining genome stability following starvation, where in its absence R-loops accumulate, resulting in reproductive compromise and DNA damage hypersensitivity.

Dual role of Ovol2 on the germ cell lineage segregation during gastrulation in mouse embryogenesis

Development ◽  
2022 ◽  
Author(s):  
Yuki Naitou ◽  
Go Nagamatsu ◽  
Nobuhiko Hamazaki ◽  
Kenjiro Shirane ◽  
Masafumi Hayashi ◽  
...  
Keyword(s):  
Germ Cells ◽  
Splice Variant ◽  
Epithelial To Mesenchymal Transition ◽  
Functional Relationship ◽  
Germ Line ◽  
Primordial Germ Cells ◽  
Cell Lineage ◽  
Animal Kingdom ◽  
Mesenchymal Transition

In mammals, primordial germ cells (PGCs), the origin of the germ line, are specified from the epiblast at the posterior region where gastrulation simultaneously occurs, yet the functional relationship between PGC specification and gastrulation remains unclear. Here, we show that Ovol2, a transcription factor conserved across the animal kingdom, balances these major developmental processes by repressing the epithelial-to-mesenchymal transition (EMT) driving gastrulation and the upregulation of genes associated with PGC specification. Ovol2a, a splice variant encoding a repressor domain, directly regulates EMT-related genes and consequently induces re-acquisition of potential pluripotency during PGC specification, whereas Ovol2b, another splice variant missing the repressor domain, directly upregulates genes associated with PGC specification. Taken together, these results elucidate the molecular mechanism underlying allocation of the germ line among epiblast cells differentiating into somatic cells through gastrulation.

63 THE EFFECT OF A MODIFIED CRYOPRESERVATION METHOD ON THE VIABILITY OF FROZEN–THAWED PRIMORDIAL GERM CELL ON THE KOREAN NATIVE CHICKEN (Ogye)

2014 ◽  
Vol 26 (1) ◽  
pp. 145
Author(s):  
H. Kim ◽  
D. H. Kim ◽  
J. Y. Han ◽  
S. B. Choi ◽  
Y.-G. Ko ◽  
...  
Keyword(s):  
Germ Cells ◽  
Germ Line ◽  
New Technology ◽  
Primordial Germ Cells ◽  
Primordial Germ Cell ◽  
Genetic Material ◽  
Trypan Blue Exclusion ◽  
Trypan Blue Exclusion Method ◽  
Native Chicken ◽  
Korean Native Chicken

Cryopreservation of poultry semen has been reported, but preservation of female genetic material has not been possible because of the unique anatomical and physiological characteristics of the avian egg. Thus, conservation of genetic material in chickens was attempted by preserving primordial germ cells (PGC) in LN2. This study established a method for preserving chicken PGC that enables long-term storage in LN2 for preservation of species. The purpose of this study was to clarify the effects of fetal bovine serum (FBS) or chicken serum (CS) treatment on the viability of cryopreserved PGC in the Korean native chicken (Ogye). Primordial germ cells were separated from a germinal gonad using a fine glass micropipette under a microscope and were suspended in a freezing medium containing freezing and protecting agents [e.g. dimethyl sulfoxide (DMSO) and ethylene glycol (EG)]. The PGC were then purified using the magnetic-activated cell sorting (MACS) method. The viability of the PGC in both groups was determined by the trypan blue exclusion method. The values of the 0, 5, 10, and 15% DMSO plus FBS treatment were 21.6, 30.36, 36.42, 50.39, and 48.36%, respectively. The viability of PGC after freeze-thawing was significantly higher for the 10% EG plus FBS treatment than for the 10% EG plus CS treatment (P < 0.05; 64.36 v. 50.66%). This study established a method for preserving chicken PGC that enables systematic storage and labelling of cryopreserved PGC in LN2 at a germplasm repository and ease of entry into a database. In the future, the importance of this new technology is that poultry lines can be conserved while work is being conducted on improving the production of germ line chimeras.

Role of leukemia inhibitory factor and its receptor in mouse primordial germ cell growth

Development ◽  
1994 ◽  
Vol 120 (11) ◽  
pp. 3145-3153 ◽  
Author(s):  
L. Cheng ◽  
D.P. Gearing ◽  
L.S. White ◽  
D.L. Compton ◽  
K. Schooley ◽  
...  
Keyword(s):  
Leukemia Inhibitory Factor ◽  
Primordial Germ Cells ◽  
Primordial Germ Cell ◽  
Oncostatin M ◽  
Inhibitory Factor ◽  
Feeder Cells ◽  
Facs Analysis ◽  
Mouse Primordial Germ Cell ◽  
Direct Target

The pleiotropic cytokine leukemia inhibitory factor (LIF) is able to promote the growth of mouse primordial germ cells (PGCs) in culture. It is unclear whether LIF acts directly on PGCs or indirectly via feeder cells or embryonic somatic cells. To understand the role of LIF in PGC growth, we have carried out molecular and cell culture analyses to investigate the role of both the LIF ligand and its receptor in PGC development. LIF is able to stimulate PGC growth independently of the presence of feeder cells supporting the hypothesis that LIF acts directly on PGCs to promote their growth. We show here that transcripts for the low-affinity LIF receptor (LIFR), an integral component of the functional LIF receptor complex, are expressed in the developing gonad. Fluorescence-activated cell sorter (FACS) analysis, using an anti-LIFR antiserum, demonstrates that LIFR is present on the surface of PGCs, suggesting that PGCs are likely to be a direct target of LIF action in culture. Signalling via LIFR is essential for PGC growth in culture since the anti-LIFR antiserum, which blocks LIF binding to its receptor, abolishes PGC survival in culture. Two LIF-related cytokines, namely oncostatin M and ciliary neurotrophic factor, can also promote PGC growth in culture in addition to LIF. Thus one or more of these LIFR-dependent cytokines may play an important role in PGC development in mice.

scholarly journals An Essential Role for a Membrane Lipid in Cytokinesis

2000 ◽  
Vol 149 (6) ◽  
pp. 1215-1224 ◽  
Author(s):  
Kazuo Emoto ◽  
Masato Umeda
Keyword(s):  
Cell Surface ◽  
Mammalian Cells ◽  
Mutant Cell ◽  
Myosin Ii ◽  
Membrane Lipid ◽  
Cleavage Furrow ◽  
Contractile Ring ◽  
Cytoplasmic Bridge ◽  
Daughter Cells

Phosphatidylethanolamine (PE) is a major membrane phospholipid that is mainly localized in the inner leaflet of the plasma membrane. We previously demonstrated that PE was exposed on the cell surface of the cleavage furrow during cytokinesis. Immobilization of cell surface PE by a PE-binding peptide inhibited disassembly of the contractile ring components, including myosin II and radixin, resulting in formation of a long cytoplasmic bridge between the daughter cells. This blockade of contractile ring disassembly was reversed by removal of the surface-bound peptide, suggesting that the PE exposure plays a crucial role in cytokinesis. To further examine the role of PE in cytokinesis, we established a mutant cell line with a specific decrease in the cellular PE level. On the culture condition in which the cell surface PE level was significantly reduced, the mutant ceased cell growth in cytokinesis, and the contractile ring remained in the cleavage furrow. Addition of PE or ethanolamine, a precursor of PE synthesis, restored the cell surface PE on the cleavage furrow and normal cytokinesis. These findings provide the first evidence that PE is required for completion of cytokinesis in mammalian cells, and suggest that redistribution of PE on the cleavage furrow may contribute to regulation of contractile ring disassembly.

scholarly journals Kinesin-like Protein CHO1 Is Required for the Formation of Midbody Matrix and the Completion of Cytokinesis in Mammalian Cells

2002 ◽  
Vol 13 (6) ◽  
pp. 1832-1845 ◽  
Author(s):  
Jurgita Matuliene ◽  
Ryoko Kuriyama
Keyword(s):  
Binding Site ◽  
Mammalian Cells ◽  
Cytoplasmic Bridge ◽  
Central Spindle ◽  
Atp Binding Site ◽  
Daughter Cells ◽  
Dividing Cells ◽  
Spindle Midzone ◽  
Segregation Of Chromosomes

CHO1 is a mammalian kinesin-like motor protein of the MKLP1 subfamily. It associates with the spindle midzone during anaphase and concentrates to a midbody matrix during cytokinesis. CHO1 was originally implicated in karyokinesis, but the invertebrate homologues of CHO1 were shown to function in the midzone formation and cytokinesis. To analyze the role of the protein in mammalian cells, we mutated the ATP-binding site of CHO1 and expressed it in CHO cells. Mutant protein (CHO1F′) was able to interact with microtubules via ATP-independent microtubule-binding site(s) but failed to accumulate at the midline of the central spindle and affected the localization of endogenous CHO1. Although the segregation of chromosomes, the bundling of midzone microtubules, and the initiation of cytokinesis proceeded normally in CHO1F′-expressing cells, the completion of cytokinesis was inhibited. Daughter cells were frequently entering interphase while connected by a microtubule-containing cytoplasmic bridge from which the dense midbody matrix was missing. Depletion of endogenous CHO1 via RNA-mediated interference also affected the formation of midbody matrix in dividing cells, caused the disorganization of midzone microtubules, and resulted in abortive cytokinesis. Thus, CHO1 may not be required for karyokinesis, but it is essential for the proper midzone/midbody formation and cytokinesis in mammalian cells.

scholarly journals Revisiting Centrioles in Nematodes—Historic Findings and Current Topics

Cells ◽  
2018 ◽  
Vol 7 (8) ◽  
pp. 101 ◽  
Author(s):  
Anna Schwarz ◽  
Prabhu Sankaralingam ◽  
Kevin O’Connell ◽  
Thomas Müller-Reichert
Keyword(s):  
Germ Line ◽  
Future Directions ◽  
C Elegans ◽  
Assembly Factors ◽  
Centriole Assembly

Theodor Boveri is considered as the “father” of centrosome biology. Boveri’s fundamental findings have laid the groundwork for decades of research on centrosomes. Here, we briefly review his early work on centrosomes and his first description of the centriole. Mainly focusing on centriole structure, duplication, and centriole assembly factors in C. elegans, we will highlight the role of this model in studying germ line centrosomes in nematodes. Last but not least, we will point to future directions of the C. elegans centrosome field.

Sign in / Sign up

Export Citation Format

Share Document