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.

scholarly journals Cystic Canal Mutants in Caenorhabditis elegans Are Defective in the Apical Membrane Domain of the Renal (Excretory) Cell

1999 ◽  
Vol 214 (1) ◽  
pp. 227-241 ◽  
Author(s):  
Matthew Buechner ◽  
David H. Hall ◽  
Harshida Bhatt ◽  
Edward M. Hedgecock
Keyword(s):  
Caenorhabditis Elegans ◽  
Apical Membrane ◽  
Membrane Domain ◽  
Excretory Cell

sma-1 encodes a betaH-spectrin homolog required for Caenorhabditis elegans morphogenesis

Development ◽  
1998 ◽  
Vol 125 (11) ◽  
pp. 2087-2098 ◽  
Author(s):  
C. McKeown ◽  
V. Praitis ◽  
J. Austin
Keyword(s):  
Plasma Membrane ◽  
Caenorhabditis Elegans ◽  
Apical Membrane ◽  
Membrane Skeleton ◽  
Elongation Rate ◽  
Apical Plasma Membrane ◽  
Wild Type ◽  
C Elegans ◽  
Lateral Membrane ◽  
Excretory Cell

Morphogenesis transforms the C. elegans embryo from a ball of cells into a vermiform larva. During this transformation, the embryo increases fourfold in length; present data indicates this elongation results from contraction of the epidermal actin cytoskeleton. In sma-1 mutants, the extent of embryonic elongation is decreased and the resulting sma-1 larvae, although viable, are shorter than normal. We find that sma-1 mutants elongate for the same length of time as wild-type embryos, but at a decreased rate. The sma-1 mutants we have isolated vary in phenotypic severity, with the most severe alleles showing the greatest decrease in elongation rate. The sma-1 gene encodes a homolog of betaH-spectrin, a novel beta-spectrin isoform first identified in Drosophila. sma-1 RNA is expressed in epithelial tissues in the C. elegans embryo: in the embryonic epidermis at the start of morphogenesis and subsequently in the developing pharynx, intestine and excretory cell. In Drosophila, betaH-spectrin associates with the apical plasma membrane of epithelial cells; beta-spectrin is found at the lateral membrane. We propose that SMA-1 is a component of an apical membrane skeleton in the C. elegans embryonic epidermis that determines the rate of elongation during morphogenesis.

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 Caenorhabditis elegans chaperonin CCT/TRiC is required for actin and tubulin biogenesis and microvillus formation in intestinal epithelial cells

2014 ◽  
Vol 25 (20) ◽  
pp. 3095-3104 ◽  
Author(s):  
Keiko Saegusa ◽  
Miyuki Sato ◽  
Katsuya Sato ◽  
Junko Nakajima-Shimada ◽  
Akihiro Harada ◽  
...  
Keyword(s):  
Caenorhabditis Elegans ◽  
Epithelial Cells ◽  
Apical Membrane ◽  
Intestinal Epithelial Cells ◽  
Intestinal Cells ◽  
Intermediate Filament Protein ◽  
Apical Surface ◽  
Intestinal Epithelial ◽  
Microtubule Network

Intestinal epithelial cells have unique apical membrane structures, known as microvilli, that contain bundles of actin microfilaments. In this study, we report that Caenorhabditis elegans cytosolic chaperonin containing TCP-1 (CCT) is essential for proper formation of microvilli in intestinal cells. In intestinal cells of cct-5(RNAi) animals, a substantial amount of actin is lost from the apical area, forming large aggregates in the cytoplasm, and the apical membrane is deformed into abnormal, bubble-like structures. The length of the intestinal microvilli is decreased in these animals. However, the overall actin protein levels remain relatively unchanged when CCT is depleted. We also found that CCT depletion causes a reduction in the tubulin levels and disorganization of the microtubule network. In contrast, the stability and localization of intermediate filament protein IFB-2, which forms a dense filamentous network underneath the apical surface, appears to be superficially normal in CCT-deficient cells, suggesting substrate specificity of CCT in the folding of filamentous cytoskeletons in vivo. Our findings demonstrate physiological functions of CCT in epithelial cell morphogenesis using whole animals.

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

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 A polarity pathway for exocyst-dependent intracellular tube extension

2020 ◽  
Author(s):  
Joshua Abrams ◽  
Jeremy Nance
Keyword(s):  
Mammalian Cells ◽  
Rho Gtpase ◽  
Tube Formation ◽  
Membrane Domain ◽  
Lumen Formation ◽  
Vesicle Tethering ◽  
C Elegans ◽  
And Function ◽  
Excretory Cell ◽  
Upstream Regulators

ABSTRACTLumen extension in intracellular tubes can occur by the directed fusion of vesicles with an invading apical membrane domain. Within the C. elegans excretory cell, which contains an intracellular tube, the exocyst vesicle-tethering complex is enriched at the lumenal membrane domain and is required for tube formation, suggesting that it targets vesicles needed for lumen extension. Here, we identify a polarity pathway that promotes intracellular tube formation by enriching the exocyst at the lumenal membrane. We show that the PAR polarity proteins PAR-6 and PKC-3/aPKC localize to the lumenal membrane domain and function within the excretory cell to promote lumen extension, similar to exocyst component SEC-5 and exocyst regulator RAL-1. Using acute protein depletion, we find that PAR-6 is required to recruit the exocyst to the lumenal membrane domain, whereas PAR-3, which functions as an exocyst receptor in mammalian cells, appears to be dispensable for exocyst localization and lumen extension. Finally, we show that the Rho GTPase CDC-42 and the RhoGEF EXC-5/FGD act as upstream regulators of lumen formation by recruiting PAR-6 and PKC-3 to the lumenal membrane. Our findings reveal a molecular pathway that connects Rho GTPase signaling, cell polarity, and vesicle-tethering proteins to promote lumen extension in intracellular tubes.

scholarly journals Robo and Ror function in a common receptor complex to regulate Wnt-mediated neurite outgrowth in Caenorhabditis elegans

2018 ◽  
Vol 115 (10) ◽  
pp. E2254-E2263 ◽  
Author(s):  
Jiaming Wang ◽  
Mei Ding
Keyword(s):  
Caenorhabditis Elegans ◽  
Growth Cones ◽  
Asymmetric Distribution ◽  
Receptor Complex ◽  
Biological Processes ◽  
Membrane Recruitment ◽  
Guidance Cues ◽  
Downstream Effector ◽  
Common Receptor

Growing axons are exposed to various guidance cues en route to their targets, but the mechanisms that govern the response of growth cones to combinations of signals remain largely elusive. Here, we found that the sole Robo receptor, SAX-3, in Caenorhabditis elegans functions as a coreceptor for Wnt/CWN-2 molecules. SAX-3 binds to Wnt/CWN-2 and facilitates the membrane recruitment of CWN-2. SAX-3 forms a complex with the Ror/CAM-1 receptor and its downstream effector Dsh/DSH-1, promoting signal transduction from Wnt to Dsh. sax-3 functions in Wnt-responsive cells and the SAX-3 receptor is restricted to the side of the cell from which the neurite is extended. DSH-1 has a similar asymmetric distribution, which is disrupted by sax-3 mutation. Taking these results together, we propose that Robo receptor can function as a Wnt coreceptor to regulate Wnt-mediated biological processes in vivo.

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