scholarly journals Wnt ligands regulate the asymmetric divisions of neuronal progenitors in C. elegans embryos

Development ◽  
2020 ◽  
Vol 147 (7) ◽  
pp. dev183186 ◽  
Author(s):  
Shilpa Kaur ◽  
Pauline Mélénec ◽  
Sabrina Murgan ◽  
Guillaume Bordet ◽  
Pierre Recouvreux ◽  
...  
Keyword(s):  
C Elegans ◽  
Neuronal Progenitors ◽  
Wnt Ligands ◽  
Asymmetric Divisions

Patterning of the C. elegans 1 degrees vulval lineage by RAS and Wnt pathways

Development ◽  
2000 ◽  
Vol 127 (23) ◽  
pp. 5047-5058 ◽  
Author(s):  
M. Wang ◽  
P.W. Sternberg
Keyword(s):  
Short Range ◽  
Precursor Cell ◽  
Ras Signaling ◽  
Cell Fates ◽  
C Elegans ◽  
Asymmetric Divisions ◽  
Anchor Cell ◽  
Wnt Pathways ◽  
Vulval Precursor Cell ◽  
Proper Orientation

In C. elegans, the descendants of the 1 degrees vulval precursor cell (VPC) establish a fixed spatial pattern of two different cell fates: E-F-F-E. The two inner granddaughters attach to the somatic gonadal anchor cell (AC) and generate four vulF cells, while the two outer granddaughters produce four vulE progeny. zmp-1::GFP, a molecular marker that distinguishes these two fates, is expressed in vulE cells, but not vulF cells. We demonstrate that a short-range AC signal is required to ensure that the pattern of vulE and vulF fates is properly established. In addition, signaling between the inner and outer 1 degrees VPC descendants, as well as intrinsic polarity of the 1 degrees VPC daughters, is involved in the asymmetric divisions of the 1 degrees VPC daughters and the proper orientation of the outcome. Finally, we provide evidence that RAS signaling is used during this new AC signaling event, while the Wnt receptor LIN-17 appears to mediate signaling between the inner and outer 1 degrees VPC descendants.

scholarly journals Physically asymmetric division of the C. elegans zygote ensures invariably successful embryogenesis

eLife ◽  
2021 ◽  
Vol 10 ◽  
Author(s):  
Radek Jankele ◽  
Rob Jelier ◽  
Pierre Gönczy
Keyword(s):  
Cell Fate ◽  
Cell Cycle Progression ◽  
Cell Lineage ◽  
External Compression ◽  
Cycle Progression ◽  
Spindle Positioning ◽  
C Elegans ◽  
Daughter Cells ◽  
Asymmetric Divisions ◽  
Cell Positioning

Asymmetric divisions that yield daughter cells of different sizes are frequent during early embryogenesis, but the importance of such a physical difference for successful development remains poorly understood. Here, we investigated this question using the first division ofCaenorhabditis elegansembryos, which yields a large AB cell and a small P1cell. We equalized AB and P1sizes using acute genetic inactivation or optogenetic manipulation of the spindle positioning protein LIN-5. We uncovered that only some embryos tolerated equalization, and that there was a size asymmetry threshold for viability. Cell lineage analysis of equalized embryos revealed an array of defects, including faster cell cycle progression in P1descendants, as well as defects in cell positioning, division orientation, and cell fate. Moreover, equalized embryos were more susceptible to external compression. Overall, we conclude that unequal first cleavage is essential for invariably successful embryonic development ofC. elegans.

pos-1 encodes a cytoplasmic zinc-finger protein essential for germline specification in C. elegans

Development ◽  
1999 ◽  
Vol 126 (1) ◽  
pp. 1-11 ◽  
Author(s):  
H. Tabara ◽  
R.J. Hill ◽  
C.C. Mello ◽  
J.R. Priess ◽  
Y. Kohara
Keyword(s):  
Germ Cell ◽  
Zinc Finger Protein ◽  
Early Embryogenesis ◽  
Cell Fates ◽  
C Elegans ◽  
Lethal Mutations ◽  
Finger Protein ◽  
Asymmetric Divisions ◽  
Maternal Mrnas ◽  
Novel Protein

Germ cells arise during early C. elegans embryogenesis from an invariant sequence of asymmetric divisions that separate germ cell precursors from somatic precursors. We show that maternal-effect lethal mutations in the gene pos-1 cause germ cell precursors to inappropriately adopt somatic cell fates. During early embryogenesis, pos-1 mRNA and POS-1 protein are present predominantly in the germ precursors. POS-1 is a novel protein with two copies of a CCCH finger motif previously described in the germline proteins PIE-1 and MEX-1 in C. elegans, and in the mammalian TIS11/Nup475/TTP protein. However, mutations in pos-1 cause several defects in the development of the germline blastomeres that are distinct from those caused by mutations in pie-1 or mex-1. The earliest defect detected in pos-1 mutants is the failure to express APX-1 protein from maternally provided apx-1 mRNA, suggesting that POS-1 may have an important role in regulating the expression of maternal mRNAs in germline blastomeres.

scholarly journals Roles of Actin in the Morphogenesis of the Early Caenorhabditis elegans Embryo

2020 ◽  
Vol 21 (10) ◽  
pp. 3652
Author(s):  
Dureen Samandar Eweis ◽  
Julie Plastino
Keyword(s):  
Cell Division ◽  
Caenorhabditis Elegans ◽  
Asymmetric Cell Division ◽  
Cell Types ◽  
Actin Dynamics ◽  
Actin Binding ◽  
Asymmetric Cell Divisions ◽  
C Elegans ◽  
Asymmetric Divisions ◽  
Different Cell Types

The cell shape changes that ensure asymmetric cell divisions are crucial for correct development, as asymmetric divisions allow for the formation of different cell types and therefore different tissues. The first division of the Caenorhabditis elegans embryo has emerged as a powerful model for understanding asymmetric cell division. The dynamics of microtubules, polarity proteins, and the actin cytoskeleton are all key for this process. In this review, we highlight studies from the last five years revealing new insights about the role of actin dynamics in the first asymmetric cell division of the early C. elegans embryo. Recent results concerning the roles of actin and actin binding proteins in symmetry breaking, cortical flows, cortical integrity, and cleavage furrow formation are described.

scholarly journals Physically asymmetric division of the C. elegans zygote ensures invariably successful embryogenesis

2021 ◽  
Author(s):  
Radek Jankele ◽  
Rob Jelier ◽  
Pierre Gönczy
Keyword(s):  
Cell Fate ◽  
Cell Cycle Progression ◽  
Cell Lineage ◽  
External Compression ◽  
Cycle Progression ◽  
Spindle Positioning ◽  
C Elegans ◽  
Daughter Cells ◽  
Asymmetric Divisions ◽  
Cell Positioning

Asymmetric divisions that yield daughter cells of different sizes are frequent during early embryogenesis, but the importance of such a physical difference for successful development remains poorly understood. Here, we investigated this question using the first division of C. elegans embryos, which yields a large AB cell and a small P1 cell. We equalized AB and P1 sizes using acute genetic inactivation or optogenetic manipulation of the spindle positioning protein LIN-5. We uncovered that only some embryos tolerated equalization and that there was a size asymmetry threshold for viability. Cell lineage analysis of equalized embryos revealed an array of defects, including faster cell cycle progression in P1 descendants, as well as defects in cell positioning, division orientation, and cell fate. Moreover, equalized embryos were more susceptible to external compression. Overall, we conclude that unequal first cleavage is essential for invariably successful embryonic development of C. elegans.

scholarly journals CEH-20/Pbx and UNC-62/Meis function upstream of rnt-1/Runx to regulate asymmetric divisions of the C. elegans stem-like seam cells

Biology Open ◽  
2013 ◽  
Vol 2 (7) ◽  
pp. 718-727 ◽  
Author(s):  
S. Hughes ◽  
C. Brabin ◽  
P. J. Appleford ◽  
A. Woollard
Keyword(s):  
C Elegans ◽  
Asymmetric Divisions

scholarly journals Cellular Analyses of the Mitotic Region in the Caenorhabditis elegans Adult Germ Line

2006 ◽  
Vol 17 (7) ◽  
pp. 3051-3061 ◽  
Author(s):  
Sarah L. Crittenden ◽  
Kimberly A. Leonhard ◽  
Dana T. Byrd ◽  
Judith Kimble
Keyword(s):  
Stem Cells ◽  
Caenorhabditis Elegans ◽  
Germ Cells ◽  
Germ Line ◽  
Germline Stem Cells ◽  
C Elegans ◽  
Brdu Label ◽  
Asymmetric Divisions ◽  
Brdu Labeling ◽  
Cell Niche

The Caenorhabditis elegans germ line provides a model for understanding how signaling from a stem cell niche promotes continued mitotic divisions at the expense of differentiation. Here we report cellular analyses designed to identify germline stem cells within the germline mitotic region of adult hermaphrodites. Our results support several conclusions. First, all germ cells within the mitotic region are actively cycling, as visualized by bromodeoxyuridine (BrdU) labeling. No quiescent cells were found. Second, germ cells in the mitotic region lose BrdU label uniformly, either by movement of labeled cells into the meiotic region or by dilution, probably due to replication. No label-retaining cells were found in the mitotic region. Third, the distal tip cell niche extends processes that nearly encircle adjacent germ cells, a phenomenon that is likely to anchor the distal-most germ cells within the niche. Fourth, germline mitoses are not oriented reproducibly, even within the immediate confines of the niche. We propose that germ cells in the distal-most rows of the mitotic region serve as stem cells and more proximal germ cells embark on the path to differentiation. We also propose that C. elegans adult germline stem cells are maintained by proximity to the niche rather than by programmed asymmetric divisions.

scholarly journals C. elegans Runx/CBFβ suppresses POP-1(TCF) to convert asymmetric to proliferative division of stem cell-like seam cells

2019 ◽  
Author(s):  
Suzanne E. M. van der Horst ◽  
Janine Cravo ◽  
Alison Woollard ◽  
Juliane Teapal ◽  
Sander van den Heuvel
Keyword(s):  
Stem Cell ◽  
Cell Division ◽  
Asymmetric Cell Division ◽  
Time Lapse ◽  
Cell Number ◽  
Self Renewal ◽  
C Elegans ◽  
Cell Divisions ◽  
Seam Cell ◽  
Asymmetric Divisions

ABSTRACTA correct balance between proliferative and asymmetric cell divisions underlies normal development, stem cell maintenance and tissue homeostasis. What determines whether cells undergo symmetric or asymmetric cell division is poorly understood. To gain insight in the mechanisms involved, we studied the stem cell-like seam cells in the Caenorhabditis elegans epidermis. Seam cells go through a reproducible pattern of asymmetric divisions, instructed by non-canonical Wnt/β-catenin asymmetry signaling, and symmetric divisions that increase the seam cell number. Using time-lapse fluorescence microscopy, we show that symmetric cell divisions maintain the asymmetric localization of Wnt/β-catenin pathway components. Observations based on lineage-specific knockout and GFP-tagging of endogenous pop-1 support the model that POP-1TCF induces differentiation at a high nuclear level, while low nuclear POP-1 promotes seam cell self-renewal. Before symmetric division, the transcriptional regulator rnt-1Runx and cofactor bro-1CBFβ temporarily bypass Wnt/β-catenin asymmetry by downregulating pop-1 expression. Thereby, RNT-1/BRO-1 appears to render POP-1 below the level required for its repressor function, which converts differentiation into self-renewal. Thus, opposition between the C. elegans Runx/CBFβ and TCF stem-cell regulators controls the switch between asymmetric and symmetric seam cell division.

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