Cytoplasmic localization and reorganization in ascidian eggs: role of postplasmic/PEM RNAs in axis formation and fate determination

2012 ◽  
Vol 1 (4) ◽  
pp. 501-518 ◽  
Author(s):  
Kazuhiro W. Makabe ◽  
Hiroki Nishida
Keyword(s):  
Axis Formation ◽  
Cytoplasmic Localization ◽  
Fate Determination

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.

scholarly journals Jagged–Delta asymmetry in Notch signaling can give rise to a Sender/Receiver hybrid phenotype

2015 ◽  
Vol 112 (5) ◽  
pp. E402-E409 ◽  
Author(s):  
Marcelo Boareto ◽  
Mohit Kumar Jolly ◽  
Mingyang Lu ◽  
José N. Onuchic ◽  
Cecilia Clementi ◽  
...  
Keyword(s):  
Notch Signaling ◽  
Cell Fate ◽  
Target Genes ◽  
Tumor Stroma ◽  
Notch Receptor ◽  
Toggle Switch ◽  
Cell Fate Determination ◽  
Asymmetric Effect ◽  
Fate Determination

Notch signaling pathway mediates cell-fate determination during embryonic development, wound healing, and tumorigenesis. This pathway is activated when the ligand Delta or the ligand Jagged of one cell interacts with the Notch receptor of its neighboring cell, releasing the Notch Intracellular Domain (NICD) that activates many downstream target genes. NICD affects ligand production asymmetrically––it represses Delta, but activates Jagged. Although the dynamical role of Notch–Jagged signaling remains elusive, it is widely recognized that Notch–Delta signaling behaves as an intercellular toggle switch, giving rise to two distinct fates that neighboring cells adopt––Sender (high ligand, low receptor) and Receiver (low ligand, high receptor). Here, we devise a specific theoretical framework that incorporates both Delta and Jagged in Notch signaling circuit to explore the functional role of Jagged in cell-fate determination. We find that the asymmetric effect of NICD renders the circuit to behave as a three-way switch, giving rise to an additional state––a hybrid Sender/Receiver (medium ligand, medium receptor). This phenotype allows neighboring cells to both send and receive signals, thereby attaining similar fates. We also show that due to the asymmetric effect of the glycosyltransferase Fringe, different outcomes are generated depending on which ligand is dominant: Delta-mediated signaling drives neighboring cells to have an opposite fate; Jagged-mediated signaling drives the cell to maintain a similar fate to that of its neighbor. We elucidate the role of Jagged in cell-fate determination and discuss its possible implications in understanding tumor–stroma cross-talk, which frequently entails Notch–Jagged communication.

scholarly journals Role of the RGS (regulator of G protein signaling) domain of Axin in vertebrate axis formation

2009 ◽  
Vol 23 (S1) ◽  
Author(s):  
Patricia Schneider ◽  
Diane Slusarski ◽  
Douglas Houston
Keyword(s):  
G Protein ◽  
Axis Formation ◽  
G Protein Signaling ◽  
Protein Signaling ◽  
Signaling Domain

scholarly journals Novel role of the muskelin–RanBP9 complex as a nucleocytoplasmic mediator of cell morphology regulation

2008 ◽  
Vol 182 (4) ◽  
pp. 727-739 ◽  
Author(s):  
Manojkumar Valiyaveettil ◽  
Amber A. Bentley ◽  
Priya Gursahaney ◽  
Rajaa Hussien ◽  
Ritu Chakravarti ◽  
...  
Keyword(s):  
Cell Morphology ◽  
Subcellular Fractionation ◽  
Cytoplasmic Localization ◽  
Intracellular Protein ◽  
Morphological Alterations ◽  
C Terminus ◽  
Evolutionarily Conserved ◽  
The Status ◽  
Interfering Rna

The evolutionarily conserved kelch-repeat protein muskelin was identified as an intracellular mediator of cell spreading. We discovered that its morphological activity is controlled by association with RanBP9/RanBPM, a protein involved in transmembrane signaling and a conserved intracellular protein complex. By subcellular fractionation, endogenous muskelin is present in both the nucleus and the cytosol. Muskelin subcellular localization is coregulated by its C terminus, which provides a cytoplasmic restraint and also controls the interaction of muskelin with RanBP9, and its atypical lissencephaly-1 homology motif, which has a nuclear localization activity which is regulated by the status of the C terminus. Transient or stable short interfering RNA–based knockdown of muskelin resulted in protrusive cell morphologies with enlarged cell perimeters. Morphology was specifically restored by complementary DNAs encoding forms of muskelin with full activity of the C terminus for cytoplasmic localization and RanBP9 binding. Knockdown of RanBP9 resulted in equivalent morphological alterations. These novel findings identify a role for muskelin–RanBP9 complex in pathways that integrate cell morphology regulation and nucleocytoplasmic communication.

scholarly journals Role of YAP/TAZ in Cell Lineage Fate Determination and Related Signaling Pathways

2020 ◽  
Vol 8 ◽  
Author(s):  
Boon C. Heng ◽  
Xuehui Zhang ◽  
Dominique Aubel ◽  
Yunyang Bai ◽  
Xiaochan Li ◽  
...  
Keyword(s):  
Signaling Pathways ◽  
Cell Lineage ◽  
Fate Determination

The IP3 receptor/Ca2+ channel and its cellular function

2007 ◽  
Vol 74 ◽  
pp. 9-22 ◽  
Author(s):  
Katsuhiko Mikoshiba
Keyword(s):  
Exocrine Secretion ◽  
Axis Formation ◽  
Ip3 Receptor ◽  
Release Channel ◽  
Saliva Secretion ◽  
Binding Core ◽  
Gastric Juice Secretion ◽  
Trisphosphate Receptor ◽  
Type 3

The IP3R [IP3 (inositol 1,4,5-trisphosphate) receptor] is responsible for Ca2+ release from the ER (endoplasmic reticulum). We have been working extensively on the P400 protein, which is deficient in Purkinje-neuron-degenerating mutant mice. We have discovered that P400 is an IP3R and we have determined the primary sequence. Purified IP3R, when incorporated into a lipid bilayer, works as a Ca2+ release channel and overexpression of IP3R shows enhanced IP3 binding and channel activity. Addition of an antibody blocks Ca2+ oscillations indicating that IP3R1 works as a Ca2+ oscillator. Studies on the role of IP3R during development show that IP3R is involved in fertilization and is essential for determination of dorso-ventral axis formation. We found that IP3R is involved in neuronal plasticity. A double homozygous mutant of IP3R2 (IP3R type 2) and IP3R3 (IP3R type 3) shows a deficit of saliva secretion and gastric juice secretion suggesting that IP3Rs are essential for exocrine secretion. IP3R has various unique properties: cryo-EM (electron microscopy) studies show that IP3R contains multiple cavities; IP3R allosterically and dynamically changes its form reversibly (square form–windmill form); IP3R is functional even though it is fragmented by proteases into several pieces; the ER forms a meshwork but also forms vesicular ER and moves along microtubules using a kinesin motor; X ray analysis of the crystal structure of the IP3 binding core consists of an N-terminal β-trefoil domain and a C-terminal α-helical domain. We have discovered ERp44 as a redox sensor in the ER which binds to the luminal part of IP3R1 and regulates its activity. We have also found the role of IP3 is not only to release Ca2+ but also to release IRBIT which binds to the IP3 binding core of IP3R.

Dominant role of the niche in melanocyte stem-cell fate determination

Nature ◽  
2002 ◽  
Vol 416 (6883) ◽  
pp. 854-860 ◽  
Author(s):  
Emi K. Nishimura ◽  
Siobhán A. Jordan ◽  
Hideo Oshima ◽  
Hisahiro Yoshida ◽  
Masatake Osawa ◽  
...  
Keyword(s):  
Stem Cell ◽  
Cell Fate ◽  
Dominant Role ◽  
Cell Fate Determination ◽  
Stem Cell Fate ◽  
Fate Determination ◽  
Melanocyte Stem Cell
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