scholarly journals Interactions between the WEE-1.3 kinase and the PAM-1 aminopeptidase in oocyte maturation and the early C. elegans embryo

2021 ◽  
Author(s):  
Dorothy Benton ◽  
Eva C Jaeger ◽  
Arielle Kilner ◽  
Ashley Kimble ◽  
Josh Lowry ◽  
...  
Keyword(s):  
Missense Mutation ◽  
Oocyte Maturation ◽  
Protective Role ◽  
C Elegans ◽  
Direct Target ◽  
The One ◽  
Actomyosin Cytoskeleton ◽  
Embryonic Viability ◽  
Anterior Posterior

Abstract Puromycin-sensitive aminopeptidases are found across phyla and are known to regulate the cell-cycle and play a protective role in neurodegenerative disease. PAM-1 is a puromycin-sensitive aminopeptidase important for meiotic exit and polarity establishment in the one-cell Caenorhabditis elegans embryo. Despite conservation of this aminopeptidase, little is known about its targets during development. In order to identify novel interactors, we conducted a suppressor screen and isolated four suppressing mutations in three genes that partially rescued the maternal-effect lethality of pam-1 mutants. Suppressed strains show improved embryonic viability and polarization of the anterior-posterior axis. We identified a missense mutation in wee-1.3 in one of these suppressed strains. WEE-1.3 is an inhibitory kinase that regulates maturation promoting factor. While the missense mutation suppressed polarity phenotypes in pam-1, it does so without restoring centrosome-cortical contact or altering the cortical actomyosin cytoskeleton. To see if PAM-1 and WEE-1.3 interact in other processes, we examined oocyte maturation. While depletion of wee-1.3 causes sterility due to precocious oocyte maturation, this effect was lessened in pam-1 worms, suggesting that PAM-1 and WEE-1.3 interact in this process. Levels of WEE-1.3 were comparable between wild-type and pam-1 strains, suggesting that WEE-1.3 is not a direct target of the aminopeptidase. Thus, we have established an interaction between PAM-1 and WEE-1.3 in multiple developmental processes and have identified suppressors that are likely to further our understanding of the role of puromycin-sensitive aminopeptidases during development.

scholarly journals ABCB transporters in a leaf beetle respond to sequestered plant toxins

2020 ◽  
Vol 287 (1934) ◽  
pp. 20201311
Author(s):  
Paulina Kowalski ◽  
Michael Baum ◽  
Marcel Körten ◽  
Alexander Donath ◽  
Susanne Dobler
Keyword(s):  
Host Plants ◽  
Leaf Beetle ◽  
Protective Role ◽  
Specific Storage ◽  
Toxic Compounds ◽  
Chrysochus Auratus ◽  
Defensive Glands ◽  
The One ◽  
Uptake And Transport

Phytophagous insects can tolerate and detoxify toxic compounds present in their host plants and have evolved intricate adaptations to this end. Some insects even sequester the toxins for their defence. This necessitates specific mechanisms, especially carrier proteins that regulate uptake and transport to specific storage sites or protect sensitive tissues from noxious compounds. We identified three ATP-binding cassette subfamily B (ABCB) transporters from the transcriptome of the cardenolide-sequestering leaf beetle Chrysochus auratus and analysed their functional role in the sequestration process. These were heterologously expressed and tested for their ability to interact with various potential substrates: verapamil (standard ABCB substrate), the cardenolides digoxin (commonly used), cymarin (present in the species's host plant) and calotropin (present in the ancestral host plants). Verapamil stimulated all three ABCBs and each was activated by at least one cardenolide, however, they differed as to which they were activated by. While the expression of the most versatile transporter fits with a protective role in the blood–brain barrier, the one specific for cymarin shows an extreme abundance in the elytra, coinciding with the location of the defensive glands. Our data thus suggest a key role of ABCBs in the transport network needed for cardenolide sequestration.

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 The kinases PIG-1 and PAR-1 act in redundant pathways to regulate asymmetric division in the EMS blastomere of C. elegans

2017 ◽  
Author(s):  
Malgorzata J. Liro ◽  
Diane G. Morton ◽  
Lesilee S. Rose
Keyword(s):  
Wnt Pathway ◽  
Asymmetric Division ◽  
Spindle Orientation ◽  
Cell Stage ◽  
Spindle Positioning ◽  
C Elegans ◽  
Stage Embryo ◽  
Cell Embryo ◽  
The One

AbstractThe PAR-1 kinase of C. elegans is localized to the posterior of the one-cell embryo and its mutations affect asymmetric spindle placement and partitioning of cytoplasmic components in the first cell cycle. However, unlike mutations in the posteriorly localized PAR-2 protein, par-1 mutations do not cause failure to restrict the anterior PAR polarity complex. Further, it has been difficult to examine the role of PAR-1 in subsequent divisions due to the early defects in par-1 mutant embryos. Here we show that the PIG-1 kinase acts redundantly with PAR-1 to restrict the anterior PAR-3 protein for polarity maintenance in the one-cell embryo. By using a weak allele of par-1 that exhibits enhanced lethality when combined with a pig-1 mutation we have further explored roles for these genes in subsequent divisions. We find that both PIG-1 and PAR-1 regulate spindle orientation in the EMS blastomere of the four-cell stage embryo to ensure that it undergoes an asymmetric division. In this cell, PIG-1 and PAR-1 act in parallel pathways for spindle positioning, PIG-1 in the MES-1/SRC-1 pathway and PAR-1 in the Wnt pathway.

scholarly journals Lactate and pyruvate promote cellular stress resistance and longevity through ROS signaling

2019 ◽  
Author(s):  
Arnaud Tauffenberger ◽  
Hubert Fiumelli ◽  
Salam Almustafa ◽  
Pierre J. Magistretti
Keyword(s):  
Energy Production ◽  
Neuroblastoma Cells ◽  
Protective Role ◽  
Antioxidant Defenses ◽  
Oxygen Species ◽  
Cellular Mechanisms ◽  
C Elegans ◽  
Survival Pathways ◽  
Lactate And Pyruvate

SummaryL-lactate, for long considered a glycolytic end-product, is now recognized as an important energy substrate. Moreover, it appears that its role is not limited to energy production but also as a signal for neuroprotection and synaptic plasticity. Using a model of neuroblastoma cells and the nematode C. elegans we investigated the cellular mechanisms underlying this protective role of L-lactate. We found that L-lactate promotes a mild Reactive Oxygen Species (ROS) induction that translates into activation of antioxidant defenses and pro-survival pathways such as PI3K/AKT and Endoplasmic Reticulum (ER) chaperones. This hormetic mechanism provides protection against oxidative stress in both cells and nematodes. Furthermore, a mild ROS induction by lactate also promotes longevity in C. elegans.

Overlapping roles of two Hox genes and the exd ortholog ceh-20 in diversification of the C. elegans postembryonic mesoderm

Development ◽  
2000 ◽  
Vol 127 (23) ◽  
pp. 5179-5190 ◽  
Author(s):  
J. Liu ◽  
A. Fire
Keyword(s):  
Hox Genes ◽  
Postembryonic Development ◽  
Striated Muscles ◽  
Hox Cluster ◽  
C Elegans ◽  
Direct Target ◽  
Mutant Phenotypes

Members of the Hox family of homeoproteins and their cofactors play a central role in pattern formation of all germ layers. During postembryonic development of C. elegans, non-gonadal mesoderm arises from a single mesoblast cell M. Starting in the first larval stage, M divides to produce 14 striated muscles, 16 non-striated muscles, and two non-muscle cells (coelomocytes). We investigated the role of the C. elegans Hox cluster and of the exd ortholog ceh-20 in patterning of the postembryonic mesoderm. By examining the M lineage and its differentiation products in different Hox mutant combinations, we found an essential but overlapping role for two of the Hox cluster genes, lin-39 and mab-5, in diversification of the postembryonic mesoderm. This role of the two Hox gene products required the CEH-20 cofactor. One target of these two Hox genes is the C. elegans twist ortholog hlh-8. Using both in vitro and in vivo assays, we demonstrated that twist is a direct target of Hox activation. We present evidence from mutant phenotypes that twist is not the only target for Hox genes in the M lineage: in particular we show that lin-39 mab-5 double mutants exhibit a more severe M lineage defect than the hlh-8 null mutant.

scholarly journals Olfactory learning primes the heat shock transcription factor HSF-1 to enhance the expression of molecular chaperone genes in C. elegans

2017 ◽  
Author(s):  
Felicia K. Ooi ◽  
Veena Prahlad
Keyword(s):  
Gene Expression ◽  
Rna Polymerase Ii ◽  
Molecular Chaperone ◽  
Pathogenic Bacteria ◽  
Environmental Enrichment ◽  
Protective Role ◽  
C Elegans ◽  
Expression Of Genes ◽  
Genes Encoding

AbstractLearning, a process by which animals modify their behavior as a result of experience, allows organisms to synthesize information from their surroundings to acquire resources and predict danger. Here we show that prior encounter with the odor of pathogenic bacteria prepares Caenorhabditis elegans to survive actual exposure to the pathogen by increasing HSF-1-dependent expression of genes encoding molecular chaperones. Learning-mediated enhancement of chaperone gene expression requires serotonin. Serotonin primes HSF-1 to enhance the expression of molecular chaperone genes by promoting its localization to RNA polymerase II–enriched nuclear loci, even prior to transcription. HSF-1-dependent chaperone gene expression ensues, however, only if and when animals encounter the pathogen. Thus, learning equips C. elegans to better survive environmental dangers by pre-emptively and specifically initiating transcriptional mechanisms throughout the whole organism. These studies provide one plausible basis for the protective role of environmental enrichment in disease.

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.

Patterning of the embryo along the anterior-posterior axis: the role of the caudal genes

Development ◽  
1997 ◽  
Vol 124 (19) ◽  
pp. 3805-3814 ◽  
Author(s):  
M. Epstein ◽  
G. Pillemer ◽  
R. Yelin ◽  
J.K. Yisraeli ◽  
A. Fainsod
Keyword(s):  
Antisense Rna ◽  
Hox Genes ◽  
Homeobox Genes ◽  
Regulatory Function ◽  
Regulatory Interactions ◽  
C Elegans ◽  
Posterior Position ◽  
Anterior Posterior ◽  
Anterior Posterior Axis

Patterning along the anterior-posterior axis takes place during gastrulation and early neurulation. Homeobox genes like Otx-2 and members of the Hox family have been implicated in this process. The caudal genes in Drosophila and C. elegans have been shown to determine posterior fates. In vertebrates, the caudal genes begin their expression during gastrulation and they take up a posterior position. By injecting sense and antisense RNA of the Xenopus caudal gene Xcad-2, we have studied a number of regulatory interactions among homeobox genes along the anterior-posterior axis. Initially, the Xcad-2 and Otx-2 genes are mutually repressed and, by late gastrulation, they mark the posterior- or anterior-most domains of the embryo, respectively. During late gastrulation and neurulation, Xcad-2 plays an additional regulatory function in relation to the Hox genes. Hox genes normally expressed anteriorly are repressed by Xcad-2 overexpression while those normally expressed posteriorly exhibit more anterior expression. The results show that the caudal genes are part of a posterior determining network which during early gastrulation functions in the subdivision of the embryo into anterior head and trunk domains. Later in gastrulation and neurulation these genes play a role in the patterning of the trunk region.

scholarly journals Insights into cisplatin-induced neurotoxicity and mitochondrial dysfunction in Caenorhabditis elegans

2021 ◽  
Author(s):  
Carmen Martinez-Fernandez ◽  
Milana Bergamino ◽  
David Brena ◽  
Natascia Ventura ◽  
Sebastian Honnen ◽  
...  
Keyword(s):  
Caenorhabditis Elegans ◽  
Protective Role ◽  
Automated System ◽  
Dopamine Synthesis ◽  
Physiological Level ◽  
Body Postures ◽  
C Elegans ◽  
Mitochondrial Functions ◽  
Dose Dependent

Cisplatin is the most common drug in first-line chemotherapy against solid tumors. We and others have previously used the nematode Caenorhabditis elegans to identify genetic factors influencing the sensitivity and resistance to cisplatin. In this study, we take advantage of C. elegans to explore cisplatin effects on mitochondrial functions and investigate cisplatin-induced neurotoxicity through a high-resolution semi-automated system for evaluating locomotion. Firstly, we report that a high-glucose diet sensitizes C. elegans to cisplatin at the physiological level and that mitochondrial CED-13 protects the cell from cisplatin-induced oxidative stress. Additionally, by assessing mitochondrial function with a Seahorse Analyzer, we observed a detrimental additive effect of cisplatin and glucose in mitochondrial respiration. Secondly, since we previously found that catechol-O-methyltransferases (involved in dopamine degradation) were upregulated upon cisplatin exposure, we studied the protective role of the FDA-approved drug dopamine against cisplatin-induced neurotoxicity. To implement the use of the Tierpsy Tracker system for measuring neurotoxicity in C. elegans, we showed that abnormal displacements and body postures in cat-2 mutants, which have the dopamine synthesis pathway disrupted, can be rescued by adding dopamine. Then, we used such a system to demonstrate that dopamine treatment protects from the dose-dependent neurotoxicity caused by cisplatin.

scholarly journals Septins and a formin have distinct functions in anaphase chiral cortical rotation in the C. elegans zygote

2021 ◽  
pp. mbc.E20-09-0576
Author(s):  
Adhham Zaatri ◽  
Jenna A. Perry ◽  
Amy Shaub Maddox
Keyword(s):  
Network Connectivity ◽  
Division Plane ◽  
C Elegans ◽  
Early Anaphase ◽  
Simultaneous Loss ◽  
Actomyosin Cytoskeleton ◽  
Future Work ◽  
The Relationship ◽  
Shed Light ◽  
Anterior Posterior

Many cells and tissues exhibit chirality that stems from the chirality of proteins and polymers. In the C. elegans zygote actomyosin contractility drives chiral rotation of the entire cortex circumferentially around the division plane during anaphase. How contractility is translated to cell-scale chirality, and what dictates handedness, are unknown. Septins are candidate contributors to cell-scale chirality because they anchor and crosslink the actomyosin cytoskeleton. We report that septins are required for anaphase cortical rotation. In contrast, the formin CYK-1, which we found to be enriched in the posterior in early anaphase, is not required for cortical rotation, but contributes to its chirality. Simultaneous loss of septin and CYK-1 function led to abnormal and often reversed cortical rotation. Our results suggest that anaphase contractility leads to chiral rotation by releasing torsional stress generated during formin-based polymerization, which is polarized along the cell anterior-posterior axis, and which accumulates due to actomyosin network connectivity. Our findings shed light on the molecular and physical bases for cellular chirality in the C. elegans zygote. We also identify conditions in which chiral rotation fails but animals are developmentally viable, opening avenues for future work on the relationship between early embryonic cellular chirality and animal body plan. [Media: see text] [Media: see text]

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