glp-1 and inductions establishing embryonic axes in C. elegans

Development ◽  
1994 ◽  
Vol 120 (7) ◽  
pp. 2051-2064 ◽  
Author(s):  
H. Hutter ◽  
R. Schnabel
Keyword(s):  
Major Part ◽  
Early Embryo ◽  
Embryonic Axes ◽  
Cell Contacts ◽  
Cell Lineages ◽  
C Elegans ◽  
Cell Embryo ◽  
Almost All ◽  
Anterior Posterior ◽  
Cell Cell

Two successive inductions specify blastomere identities, that is complex cell lineages and not specific tissues, in a major part of the early C. elegans embryo. The first induction acts along the anterior-posterior axis of the embryo and the second along the left-right axis. During the first induction a specific lineage program is induced in the posterior of the two AB blastomeres present in the four cell embryo. During the second induction, almost all of the left-right differences of the embryo are specified by interactions between a single signalling blastomere, MS, and the AB blastomeres that surround it. In both cases the inductions break the equivalence of pairs of blastomeres. The inductions correlate with the cell-cell contacts to the inducing blastomeres. The stereotype cleavage patterns of the early embryo results in invariant cell-cell contacts that guarantee the specificity of the inductions. Both inductions are affected in embryos mutant for glp-1 suggesting that in both cases glp-1 is involved in the reception of the signal.

par-6, a gene involved in the establishment of asymmetry in early C. elegans embryos, mediates the asymmetric localization of PAR-3

Development ◽  
1996 ◽  
Vol 122 (10) ◽  
pp. 3133-3140 ◽  
Author(s):  
J.L. Watts ◽  
B. Etemad-Moghadam ◽  
S. Guo ◽  
L. Boyd ◽  
B.W. Draper ◽  
...  
Keyword(s):  
Early Embryo ◽  
Cell Periphery ◽  
Loss Of Function ◽  
P Granules ◽  
C Elegans ◽  
Lethal Mutations ◽  
Cell Embryo ◽  
New Gene ◽  
The One ◽  
Anterior Posterior

The generation of asymmetry in the one-cell embryo of Caenorhabditis elegans is necessary to establish the anterior-posterior axis and to ensure the proper identity of early blastomeres. Maternal-effect lethal mutations with a partitioning defective phenotype (par) have identified several genes involved in this process. We have identified a new gene, par-6, which acts in conjunction with other par genes to properly localize cytoplasmic components in the early embryo. The early phenotypes of par-6 embryos include the generation of equal-sized blastomeres, improper localization of P granules and SKN-1 protein, and abnormal second division cleavage patterns. Overall, this phenotype is very similar to that caused by mutations in a previously described gene, par-3. The probable basis for this similarity is revealed by our genetic and immunolocalization results; par-6 acts through par-3 by localizing or maintaining the PAR-3 protein at the cell periphery. In addition, we find that loss-of-function par-6 mutations act as dominant bypass suppressors of loss-of-function mutations in par-2.

Anucleate Caenorhabditis elegans sperm can crawl, fertilize oocytes and direct anterior-posterior polarization of the 1-cell embryo

Development ◽  
2000 ◽  
Vol 127 (2) ◽  
pp. 355-366 ◽  
Author(s):  
P.L. Sadler ◽  
D.C. Shakes
Keyword(s):  
Cellular Transformation ◽  
Sperm Nucleus ◽  
Sperm Chromatin ◽  
Egg Activation ◽  
C Elegans ◽  
Oocyte Meiosis ◽  
Cell Embryo ◽  
First Time ◽  
Anterior Posterior

It has long been appreciated that spermiogenesis, the cellular transformation of sessile spermatids into motile spermatozoa, occurs in the absence of new DNA transcription. However, few studies have addressed whether the physical presence of a sperm nucleus is required either during spermiogenesis or for subsequent sperm functions during egg activation and early zygotic development. To determine the role of the sperm nucleus in these processes, we analyzed two C. elegans mutants whose spermatids lack DNA. Here we show that these anucleate sperm not only differentiate into mature functional spermatozoa, but they also crawl toward and fertilize oocytes. Furthermore, we show that these anucleate sperm induce both normal egg activation and anterior-posterior polarity in the 1-cell C. elegans embryo. The latter finding demonstrates for the first time that although the anterior-posterior embryonic axis in C. elegans is specified by sperm, the sperm pronucleus itself is not required. Also unaffected is the completion of oocyte meiosis, formation of an impermeable eggshell, migration of the oocyte pronucleus, and the separation and expansion of the sperm-contributed centrosomes. Our investigation of these mutants confirms that, in C. elegans, neither the sperm chromatin mass nor a sperm pronucleus is required for spermiogenesis, proper egg activation, or the induction of anterior-posterior polarity.

scholarly journals Planar cell polarity in the C. elegans embryo emerges by differential retention of aPARs at cell-cell contacts

2019 ◽  
Author(s):  
Priyanka Dutta ◽  
Devang Odedra ◽  
Christian Pohl
Keyword(s):  
Cell Polarity ◽  
Rho Gtpases ◽  
Planar Cell Polarity ◽  
Apical Cell ◽  
Cell Contacts ◽  
C Elegans ◽  
Medial Cortex ◽  
Differential Retention ◽  
Cell Intercalation ◽  
Cell Cell

AbstractFormation of the anteroposterior and dorsoventral body axis in the Caenorhabditis elegans embryo depends on cortical actomyosin flows and advection of polarity determinants. The role of this patterning mechanism in tissue polarization immediately after formation of cell-cell contacts is not fully understood. Here, we demonstrate that planar cell polarity (PCP) is established in the C. elegans embryo at the time of left-right (l/r) symmetry breaking. At this stage, centripetal cortical flows asymmetrically and differentially advect anterior polarity determinants (aPARs) PAR-3, PAR-6 and PKC-3 from cell-cell contacts to the medial cortex, which results in their unmixing from apical myosin. Advection generally requires GSK-3 and CDC-42, while advection of PAR-6 specifically depends on the RhoGAP PAC-1. Concurrent asymmetric retention of PAR-3, E-cadherin/HMR-1, PAC-1 and opposing retention of the antagonistic Wnt pathway components APC/APR-1 and Frizzled/MOM-5 at apical cell-cell contacts leads to planar asymmetries. The most obvious mark of PCP, asymmetric retention of PAR-3 at posterior cell-cell contacts on the left side of the embryo, is required for proper cytokinetic cell intercalation. Hence, our data uncover how PCP can be established through Wnt signaling as well as dissociation and planar asymmetric retention of aPARs mediated by distinct Rho GTPases and their regulators.

scholarly journals The early embryonic development of the satellite organism Pristionchus pacificus: differences and similarities with Caenorhabditis elegans

Nematology ◽  
2008 ◽  
Vol 10 (3) ◽  
pp. 301-312 ◽  
Author(s):  
Gaetan Borgonie ◽  
Wim Bert ◽  
Wouter Houthoofd ◽  
Sandra Vangestel
Keyword(s):  
Caenorhabditis Elegans ◽  
Embryonic Development ◽  
Early Development ◽  
Model Organism ◽  
Embryonic Cell ◽  
Early Embryonic Development ◽  
Cell Contacts ◽  
Pristionchus Pacificus ◽  
C Elegans ◽  
Cell Cell

AbstractAs a comparative counterpart for the model organism Caenorhabditis elegans, the nematode Pristionchus pacificus was established as a satellite organism to study developmental processes. However, these studies mainly focused on post-embryonic development and little is known about the early embryonic development. Using 4D microscopy we reconstructed the early embryonic cell lineage of 12 individuals of P. pacificus. By analysing several parameters of early development, including the division sequence, the spatial arrangement of blastomeres, the cell cycle patterns of the AB lineage and cell-cell contacts in different cell stages of the embryo, it was shown that the early embryonic development is nearly identical to C. elegans. Known cell-cell contacts necessary for induction of blastomere fates in C. elegans are also present in P. pacificus. Thus, the spatio-temporal conditions that would allow possible homologous inductions are present. However, at least one model for blastomere specification seems not to apply to P. pacificus since the third division in the AB lineage differs from that of C. elegans. Furthermore, naturally occurring variability of early development was demonstrated, which is clearly permitted since there seems to be no influence on further development into an adult worm.

Expression of the homeotic gene mab-5 during Caenorhabditis elegans embryogenesis

Development ◽  
1992 ◽  
Vol 116 (2) ◽  
pp. 481-490 ◽  
Author(s):  
D.W. Cowing ◽  
C. Kenyon
Keyword(s):  
Early Stage ◽  
Postembryonic Development ◽  
Early Embryogenesis ◽  
Lacz Fusion ◽  
Homeotic Genes ◽  
Specific Expression ◽  
C Elegans ◽  
Developmental Factors ◽  
Cell Embryo ◽  
Anterior Posterior

mab-5 is a member of a complex of homeobox-containing genes evolutionarily related to the Antennapedia and bithorax complexes of Drosophila melanogaster. Like the homeotic genes in Drosophila, mab-5 is required in a particular region along the anterior-posterior body axis, and acts during postembryonic development to give cells in this region their characteristic identities. We have used a mab-5-lacZ fusion integrated into the C. elegans genome to study the posterior-specific expression of mab-5 during embryogenesis. The mab-5-lacZ fusion was expressed in the posterior of the embryo by 180 minutes after the first cleavage, indicating that the mechanisms responsible for the position-specific expression of mab-5-lacZ act at a relatively early stage of embryogenesis. In embryos homozygous for mutations in the par genes, which disrupt segregation of factors during early cleavages, expression of mab-5-lacZ was no longer localized to the posterior. This suggests that posterior-specific expression of mab-5 depends on the appropriate segregation of developmental factors during early embryogenesis. After extrusion of any blastomere of the four-cell embryo, descendants of the remaining three cells could still express the mab-5-lacZ fusion. In these partial embryos, however, the fusion was often expressed in cells scattered throughout the embryo, suggesting that cell-cell interactions and/or proper positioning of early blastomeres are required for mab-5 expression to be localized to the posterior.

scholarly journals Identification of the critical replication targets of CDK reveals direct regulation of replication initiation factors by the embryo polarity machinery in C. elegans

2020 ◽  
Author(s):  
Vincent Gaggioli ◽  
Manuela R. Kieninger ◽  
Anna Klucnika ◽  
Richard Butler ◽  
Philip Zegerman
Keyword(s):  
Cell Cycle ◽  
Tumour Progression ◽  
Early Embryo ◽  
S Phase ◽  
Replication Initiation ◽  
Cell Lineages ◽  
C Elegans ◽  
Initiation Factors ◽  
Essential Function ◽  
Phase Length

AbstractDuring metazoan development, the cell cycle is remodelled to coordinate proliferation with differentiation. Developmental cues cause dramatic changes in the number and timing of replication initiation events, but the mechanisms and physiological importance of such changes are poorly understood. Cyclin-dependent kinase (CDK) is important for regulating S-phase length in many metazoa, and here we show in the nematode Caenorhabditis elegans that an essential function of CDK during early embryogenesis is to regulate the interactions between three replication initiation factors SLD-3, SLD-2 and MUS-101 (Dpb11/TopBP1). Mutations that bypass the requirement for CDK to generate interactions between these factors is sufficient for viability in the absence of CyclinE/Cdk2, demonstrating that this is a critical embryonic function of this cyclin/CDK complex. Both SLD-2 and SLD-3 are asymmetrically localised in the early embryo and the levels of these proteins inversely correlate with S-phase length. We also show that SLD-2 asymmetry is determined by direct interaction with the polarity protein PKC-3. This study explains the essential function of CDK for replication initiation in a metazoan and provides the first direct molecular mechanism through which polarization of the embryo is coordinated with DNA replication initiation.Author SummaryHow and when a cell divides changes as the cell assumes different fates. How these changes in cell division are brought about are poorly understood, but are critical to ensure that cells do not over-proliferate leading to cancer. The nematode C. elegans is an excellent system to study the role of cell cycle changes during animal development. Here we show that two factors SLD-2 and SLD-3 are critical to control the decision to begin genome duplication. We show that these factors are differently distributed to different cell lineages in the early embryo, which may be a key event in determining the cell cycle rate in these cells. For the first time we show that, PKC-3, a key component of the machinery that determines the front (anterior) from the back (posterior) of the embryo directly controls SLD-2 distribution, which might explain how the polarisation of the embryo causes changes in the proliferation of different cell lineages. As PKC-3 is frequently mutated in human cancers, how this factor controls cell proliferation may be important to understand tumour progression.

Centrosome Aurora A gradient ensures single polarity axis in C. elegans embryos

2020 ◽  
Vol 48 (3) ◽  
pp. 1243-1253 ◽  
Author(s):  
Sukriti Kapoor ◽  
Sachin Kotak
Keyword(s):  
Symmetry Breaking ◽  
Cell Fate ◽  
Cell Cortex ◽  
Axis Formation ◽  
Aurora A Kinase ◽  
Aurora A ◽  
C Elegans ◽  
Cell Embryo ◽  
Polarity Establishment

Cellular asymmetries are vital for generating cell fate diversity during development and in stem cells. In the newly fertilized Caenorhabditis elegans embryo, centrosomes are responsible for polarity establishment, i.e. anterior–posterior body axis formation. The signal for polarity originates from the centrosomes and is transmitted to the cell cortex, where it disassembles the actomyosin network. This event leads to symmetry breaking and the establishment of distinct domains of evolutionarily conserved PAR proteins. However, the identity of an essential component that localizes to the centrosomes and promotes symmetry breaking was unknown. Recent work has uncovered that the loss of Aurora A kinase (AIR-1 in C. elegans and hereafter referred to as Aurora A) in the one-cell embryo disrupts stereotypical actomyosin-based cortical flows that occur at the time of polarity establishment. This misregulation of actomyosin flow dynamics results in the occurrence of two polarity axes. Notably, the role of Aurora A in ensuring a single polarity axis is independent of its well-established function in centrosome maturation. The mechanism by which Aurora A directs symmetry breaking is likely through direct regulation of Rho-dependent contractility. In this mini-review, we will discuss the unconventional role of Aurora A kinase in polarity establishment in C. elegans embryos and propose a refined model of centrosome-dependent symmetry breaking.

Characterization of N-cadherin-containing cell-cell contacts of the liver

2006 ◽  
Vol 44 (01) ◽  
Author(s):  
BK Straub ◽  
J Boda-Heggemann ◽  
UF Pape ◽  
C Grund ◽  
E Specht-Delius ◽  
...  
Keyword(s):  
Cell Contacts ◽  
Cell Cell
Sign in / Sign up

Export Citation Format

Share Document