Cortical forces and CDC-42 control clustering of PAR proteins for Caenorhabditis elegans embryonic polarization

2017 ◽  
Vol 19 (8) ◽  
pp. 988-995 ◽  
Author(s):  
Shyi-Chyi Wang ◽  
Tricia Yu Feng Low ◽  
Yukako Nishimura ◽  
Laurent Gole ◽  
Weimiao Yu ◽  
...  
Keyword(s):  
Caenorhabditis Elegans ◽  
Par Proteins

scholarly journals PAR-3 and PAR-1 Inhibit LET-99 Localization to Generate a Cortical Band Important for Spindle Positioning in Caenorhabditis elegans Embryos

2007 ◽  
Vol 18 (11) ◽  
pp. 4470-4482 ◽  
Author(s):  
Jui-Ching Wu ◽  
Lesilee S. Rose
Keyword(s):  
Caenorhabditis Elegans ◽  
Cell Fate ◽  
Protein Signaling ◽  
Posterior Cortex ◽  
Par Proteins ◽  
Anterior Cortex ◽  
Spindle Positioning ◽  
High Let ◽  
Fate Determinants ◽  
Cell Fate Determinants

The conserved PAR proteins are localized in asymmetric cortical domains and are required for the polarized localization of cell fate determinants in many organisms. In Caenorhabditis elegans embryos, LET-99 and G protein signaling act downstream of the PARs to regulate spindle positioning and ensure asymmetric division. PAR-3 and PAR-2 localize LET-99 to a posterior cortical band through an unknown mechanism. Here we report that LET-99 asymmetry depends on cortically localized PAR-1 and PAR-4 but not on cytoplasmic polarity effectors. In par-1 and par-4 embryos, LET-99 accumulates at the entire posterior cortex, but remains at low levels at the anterior cortex occupied by PAR-3. Further, PAR-3 and PAR-1 have graded cortical distributions with the highest levels at the anterior and posterior poles, respectively, and the lowest levels of these proteins correlate with high LET-99 accumulation. These results suggest that PAR-3 and PAR-1 inhibit the localization of LET-99 to generate a band pattern. In addition, PAR-1 kinase activity is required for the inhibition of LET-99 localization, and PAR-1 associates with LET-99. Finally, examination of par-1 embryos suggests that the banded pattern of LET-99 is critical for normal posterior spindle displacement and to prevent spindle misorientation caused by cell shape constraints.

scholarly journals A polarity pathway for exocyst-dependent intracellular tube extension

eLife ◽  
2021 ◽  
Vol 10 ◽  
Author(s):  
Joshua Abrams ◽  
Jeremy Nance
Keyword(s):  
Caenorhabditis Elegans ◽  
Apical Membrane ◽  
Par Proteins ◽  
Membrane Recruitment ◽  
Vesicle Tethering ◽  
Protein Depletion ◽  
Excretory Cell

Lumen extension in intracellular tubes can occur when vesicles fuse with an invading apical membrane. Within theCaenorhabditis elegansexcretory cell, which forms an intracellular tube, the exocyst vesicle-tethering complex is enriched at the lumenal membrane and is required for its outgrowth, suggesting that exocyst-targeted vesicles extend the lumen. Here, we identify a pathway that promotes intracellular tube extension by enriching the exocyst at the lumenal membrane. We show that PAR-6 and PKC-3/aPKC concentrate at the lumenal membrane and promote lumen extension. Using acute protein depletion, we find that PAR-6 is required for exocyst membrane recruitment, whereas PAR-3, which can recruit the exocyst in mammals, appears dispensable for exocyst localization and lumen extension. Finally, we show that CDC-42 and RhoGEF EXC-5/FGD regulate lumen extension by recruiting PAR-6 and PKC-3 to the lumenal membrane. Our findings reveal a pathway that connects CDC-42, PAR proteins, and the exocyst to extend intracellular tubes.

Extending from PARs in Caenorhabditis elegans to homologues in Haemonchus contortus and other parasitic nematodes

Parasitology ◽  
2006 ◽  
Vol 134 (4) ◽  
pp. 461-482 ◽  
Author(s):  
S. NIKOLAOU ◽  
R. B. GASSER
Keyword(s):  
Caenorhabditis Elegans ◽  
Haemonchus Contortus ◽  
Asymmetric Cell Division ◽  
Small Ruminants ◽  
Future Research ◽  
Parasitic Nematodes ◽  
Par Proteins ◽  
Surface Receptors ◽  
Cytoskeletal Dynamics ◽  
Free Living Nematode

Signal transduction molecules play key roles in the regulation of developmental processes, such as morphogenesis, organogenesis and cell differentiation in all organisms. They are organized into ‘pathways’ that represent a coordinated network of cell-surface receptors and intracellular molecules, being involved in sensing environmental stimuli and transducing signals to regulate or modulate cellular processes, such as gene expression and cytoskeletal dynamics. A particularly important group of molecules implicated in the regulation of the cytoskeleton for the establishment and maintenance of cell polarity is the PAR proteins (derived from partition defective in asymmetric cell division). The present article reviews salient aspects of PAR proteins involved in the early embryonic development and morphogenesis of the free-living nematode Caenorhabditis elegans and some other organisms, with an emphasis on the molecule PAR-1. Recent advances in the knowledge and understanding of PAR-1 homologues from the economically important parasitic nematode, Haemonchus contortus, of small ruminants is summarized and discussed in the context of exploring avenues for future research in this area for parasitic nematodes.

scholarly journals Myosin and the PAR proteins polarize microfilament-dependent forces that shape and position mitotic spindles in Caenorhabditis elegans

2003 ◽  
Vol 161 (1) ◽  
pp. 21-26 ◽  
Author(s):  
Aaron F. Severson ◽  
Bruce Bowerman
Keyword(s):  
Caenorhabditis Elegans ◽  
Myosin Ii ◽  
Embryonic Cells ◽  
Mitotic Spindles ◽  
Posterior Cortex ◽  
Par Proteins ◽  
Nonmuscle Myosin Ii ◽  
Embryonic Polarity ◽  
Cortical Localization ◽  
Actomyosin Cytoskeleton

In Caenorhabditis elegans, the partitioning proteins (PARs), microfilaments (MFs), dynein, dynactin, and a nonmuscle myosin II all localize to the cortex of early embryonic cells. Both the PARs and the actomyosin cytoskeleton are required to polarize the anterior-posterior (a-p) body axis in one-cell zygotes, but it remains unknown how MFs influence embryonic polarity. Here we show that MFs are required for the cortical localization of PAR-2 and PAR-3. Furthermore, we show that PAR polarity regulates MF-dependent cortical forces applied to astral microtubules (MTs). These forces, which appear to be mediated by dynein and dynactin, produce changes in the shape and orientation of mitotic spindles. Unlike MFs, dynein, and dynactin, myosin II is not required for the production of these forces. Instead, myosin influences embryonic polarity by limiting PAR-3 to the anterior cortex. This in turn produces asymmetry in the forces applied to MTs at each pole and allows PAR-2 to accumulate in the posterior cortex of a one-cell zygote and maintain asymmetry.

The glycomes of Caenorhabditis elegans and other model organisms

2002 ◽  
Vol 69 ◽  
pp. 117-134 ◽  
Author(s):  
Stuart M. Haslam ◽  
David Gems ◽  
Howard R. Morris ◽  
Anne Dell
Keyword(s):  
Caenorhabditis Elegans ◽  
Current Knowledge ◽  
Structural Data ◽  
Model Organisms ◽  
Entire Genome ◽  
C Elegans ◽  
The Face ◽  
Area Of Concern ◽  
Nematode Worm

There is no doubt that the immense amount of information that is being generated by the initial sequencing and secondary interrogation of various genomes will change the face of glycobiological research. However, a major area of concern is that detailed structural knowledge of the ultimate products of genes that are identified as being involved in glycoconjugate biosynthesis is still limited. This is illustrated clearly by the nematode worm Caenorhabditis elegans, which was the first multicellular organism to have its entire genome sequenced. To date, only limited structural data on the glycosylated molecules of this organism have been reported. Our laboratory is addressing this problem by performing detailed MS structural characterization of the N-linked glycans of C. elegans; high-mannose structures dominate, with only minor amounts of complex-type structures. Novel, highly fucosylated truncated structures are also present which are difucosylated on the proximal N-acetylglucosamine of the chitobiose core as well as containing unusual Fucα1–2Gal1–2Man as peripheral structures. The implications of these results in terms of the identification of ligands for genomically predicted lectins and potential glycosyltransferases are discussed in this chapter. Current knowledge on the glycomes of other model organisms such as Dictyostelium discoideum, Saccharomyces cerevisiae and Drosophila melanogaster is also discussed briefly.

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