scholarly journals RTKN-1/Rhotekin shields endosome-associated F-actin from disassembly to ensure endocytic recycling

2021 ◽  
Vol 220 (5) ◽  
Author(s):  
Yanling Yan ◽  
Shuai Liu ◽  
Can Hu ◽  
Chaoyi Xie ◽  
Linyue Zhao ◽  
...  
Keyword(s):  
Network Architecture ◽  
Intramolecular Interaction ◽  
Binding Capacity ◽  
Regulatory Protein ◽  
Actin Dynamics ◽  
Mutant Form ◽  
Actin Network ◽  
Endocytic Recycling ◽  
C Elegans

Cargo sorting and the subsequent membrane carrier formation require a properly organized endosomal actin network. To better understand the actin dynamics during endocytic recycling, we performed a genetic screen in C. elegans and identified RTKN-1/Rhotekin as a requisite to sustain endosome-associated actin integrity. Loss of RTKN-1 led to a prominent decrease in actin structures and basolateral recycling defects. Furthermore, we showed that the presence of RTKN-1 thwarts the actin disassembly competence of UNC-60A/cofilin. Consistently, in RTKN-1–deficient cells, UNC-60A knockdown replenished actin structures and alleviated the recycling defects. Notably, an intramolecular interaction within RTKN-1 could mediate the formation of oligomers. Overexpression of an RTKN-1 mutant form that lacks self-binding capacity failed to restore actin structures and recycling flow in rtkn-1 mutants. Finally, we demonstrated that SDPN-1/Syndapin acts to direct the recycling endosomal dwelling of RTKN-1 and promotes actin integrity there. Taken together, these findings consolidated the role of SDPN-1 in organizing the endosomal actin network architecture and introduced RTKN-1 as a novel regulatory protein involved in this process.

scholarly journals Spatial integration of mechanical forces by alpha-actinin establishes actin network symmetry

2019 ◽  
Author(s):  
Fabrice Senger ◽  
Amandine Pitaval ◽  
Hajer Ennomani ◽  
Laetitia Kurzawa ◽  
Laurent Blanchoin ◽  
...  
Keyword(s):  
Network Architecture ◽  
Spatial Organization ◽  
Global Network ◽  
Mechanical Forces ◽  
Spatial Integration ◽  
Actin Network ◽  
Entire Cell ◽  
Extracellular Microenvironment ◽  
Extracellular Environment

Cell and tissue morphogenesis depend on the production and spatial organization of tensional forces in the actin cytoskeleton. Actin network architecture is complex because it is made of distinct modules in which filaments adopt a variety of organizations. The assembly and dynamics of these modules is well described but the self-organisation rules directing the global network architecture are much less understood. Here we investigated the mechanism regulating the interplay between network architecture and the geometry of cell’s extracellular environment. We found that α-actinin, a filament crosslinker, is essential for network symmetry to be consistent with extracellular microenvironment symmetry. It appeared to be required for the interconnection of transverse arcs with radial fibres to ensure an appropriate balance between forces at cell adhesions and across the entire actin network. Furthermore, the connectivity of the actin network appeared necessary for the cell ability to integrate and adapt to complex patterns of extracellular cues as they migrate. Altogether, our study has unveiled a role of actin-filament crosslinking in the physical integration of mechanical forces throughout the entire cell, and the role of this integration in the establishment and adaptation of intracellular symmetry axes in accordance with the geometry of extracellular cues.

scholarly journals Arp2/3 mediates early endosome dynamics necessary for the maintenance of PAR asymmetry in Caenorhabditis elegans

2012 ◽  
Vol 23 (10) ◽  
pp. 1917-1927 ◽  
Author(s):  
Jessica M. Shivas ◽  
Ahna R. Skop
Keyword(s):  
Caenorhabditis Elegans ◽  
Maintenance Phase ◽  
Early Endosome ◽  
Actin Dynamics ◽  
Cellular Polarity ◽  
Cortical Actin ◽  
Endocytic Recycling ◽  
C Elegans ◽  
Early Endosomes ◽  
Stable Maintenance

The widely conserved Arp2/3 complex regulates branched actin dynamics that are necessary for a variety of cellular processes. In Caenorhabditis elegans, the actin cytoskeleton has been extensively characterized in its role in establishing PAR asymmetry; however, the contributions of actin to the maintenance of polarity before the onset of mitosis are less clear. Endocytic recycling has emerged as a key mechanism in the dynamic stabilization of cellular polarity, and the large GTPase dynamin participates in the stabilization of cortical polarity during maintenance phase via endocytosis in C. elegans. Here we show that disruption of Arp2/3 function affects the formation and localization of short cortical actin filaments and foci, endocytic regulators, and polarity proteins during maintenance phase. We detect actin associated with events similar to early endosomal fission, movement of endosomes into the cytoplasm, and endosomal movement from the cytoplasm to the plasma membrane, suggesting the involvement of actin in regulating processes at the early endosome. We also observe aberrant accumulations of PAR-6 cytoplasmic puncta near the centrosome along with early endosomes. We propose a model in which Arp2/3 affects the efficiency of rapid endocytic recycling of polarity cues that ultimately contributes to their stable maintenance.

scholarly journals LET-413/Erbin acts as a RAB-5 effector to promote RAB-10 activation during endocytic recycling

2017 ◽  
Vol 217 (1) ◽  
pp. 299-314 ◽  
Author(s):  
Hang Liu ◽  
Shimin Wang ◽  
Weijian Hang ◽  
Jinghu Gao ◽  
Wenjuan Zhang ◽  
...  
Keyword(s):  
Interacting Proteins ◽  
Guanine Nucleotide ◽  
Nucleotide Exchange ◽  
Endocytic Recycling ◽  
Binding Partner ◽  
C Elegans ◽  
Intestinal Epithelia ◽  
Guanine Nucleotide Exchange ◽  
Nucleotide Exchange Factor

RAB-10/Rab10 is a master regulator of endocytic recycling in epithelial cells. To better understand the regulation of RAB-10 activity, we sought to identify RAB-10(GDP)–interacting proteins. One novel RAB-10(GDP)–binding partner that we identified, LET-413, is the Caenorhabditis elegans homologue of Scrib/Erbin. Here, we focus on the mechanistic role of LET-413 in the regulation of RAB-10 within the C. elegans intestine. We show that LET-413 is a RAB-5 effector and colocalizes with RAB-10 on endosomes, and the overlap of LET-413 with RAB-10 is RAB-5 dependent. Notably, LET-413 enhances the interaction of DENN-4 with RAB-10(GDP) and promotes DENN-4 guanine nucleotide exchange factor activity toward RAB-10. Loss of LET-413 leads to cytosolic dispersion of the RAB-10 effectors TBC-2 and CNT-1. Finally, we demonstrate that the loss of RAB-10 or LET-413 results in abnormal overextensions of lateral membrane. Hence, our studies indicate that LET-413 is required for DENN-4–mediated RAB-10 activation, and the LET-413–assisted RAB-5 to RAB-10 cascade contributes to the integrity of C. elegans intestinal epithelia.

scholarly journals N-WASP regulates the mobility of the B cell receptor and co-receptors during signaling activation

2019 ◽  
Author(s):  
Ivan Rey-Suarez ◽  
Brittany Wheatley ◽  
Peter Koo ◽  
Zhou Shu ◽  
Simon Mochrie ◽  
...  
Keyword(s):  
B Cell ◽  
Single Molecule ◽  
Regulatory Protein ◽  
Cell Receptor ◽  
Receptor Activation ◽  
B Cell Receptor ◽  
Fine Tuning ◽  
Actin Dynamics ◽  
Signaling Activation

AbstractRegulation of membrane receptor mobility is important in tuning the cell’s response to external signals. This is particularly relevant in the context of immune receptor signaling. The binding of B cell receptors (BCR) to antigen induces B cell receptor activation. While actin dynamics and BCR signaling are known to be linked, the role of actin dynamics in modulating receptor mobility is not well understood. Here, we use single molecule imaging to examine BCR movement during signaling activation and examine the role of actin dynamics on BCR mobility. We use a novel machine learning based method to classify BCR trajectories into distinct diffusive states and show that the actin regulatory protein N-WASP regulates receptor mobility. Constitutive loss or acute inhibition of N-WASP, which is associated with enhanced signaling, leads to a predominance of BCR trajectories with lower diffusivity and is correlated with a decrease in actin dynamics. Furthermore, loss of N-WASP reduces diffusivity of CD19, a stimulatory co-receptor of the BCR but not that of unstimulated FcγRIIB, an inhibitory co-receptor. The effect of N-WASP is mirrored by inhibition of the Arp2/3 complex and formins. Our results implicate the dynamic actin network in fine-tuning receptor mobility and receptor-ligand interactions, thereby modulating B cell signaling.

scholarly journals Syndapin/SDPN-1 is required for endocytic recycling and endosomal actin association in the Caenorhabditis elegans intestine

2016 ◽  
Vol 27 (23) ◽  
pp. 3746-3756 ◽  
Author(s):  
Adenrele M. Gleason ◽  
Ken C. Q. Nguyen ◽  
David H. Hall ◽  
Barth D. Grant
Keyword(s):  
Caenorhabditis Elegans ◽  
Membrane Lipids ◽  
Actin Dynamics ◽  
Endocytic Recycling ◽  
Recycling Endosome ◽  
Recycling Endosomes ◽  
Bar Domain ◽  
C Elegans ◽  
Early Endosomes

Syndapin/pascin-family F-BAR domain proteins bind directly to membrane lipids and are associated with actin dynamics at the plasma membrane. Previous reports also implicated mammalian syndapin 2 in endosome function during receptor recycling, but precise analysis of a putative recycling function for syndapin in mammalian systems is difficult because of its effects on the earlier step of endocytic uptake and potential redundancy among the three separate genes that encode mammalian syndapin isoforms. Here we analyze the endocytic transport function of the only Caenorhabditis elegans syndapin, SDPN-1. We find that SDPN-1 is a resident protein of the early and basolateral recycling endosomes in the C. elegans intestinal epithelium, and sdpn-1 deletion mutants display phenotypes indicating a block in basolateral recycling transport. sdpn-1 mutants accumulate abnormal endosomes positive for early endosome and recycling endosome markers that are normally separate, and such endosomes accumulate high levels of basolateral recycling cargo. Furthermore, we observed strong colocalization of endosomal SDPN-1 with the F-actin biosensor Lifeact and found that loss of SDPN-1 greatly reduced Lifeact accumulation on early endosomes. Taken together, our results provide strong evidence for an in vivo function of syndapin in endocytic recycling and suggest that syndapin promotes transport via endosomal fission.

scholarly journals Cortical flow aligns actin filaments to form a furrow

eLife ◽  
2016 ◽  
Vol 5 ◽  
Author(s):  
Anne-Cecile Reymann ◽  
Fabio Staniscia ◽  
Anna Erzberger ◽  
Guillaume Salbreux ◽  
Stephan W Grill
Keyword(s):  
Actin Filaments ◽  
Network Architecture ◽  
Ring Formation ◽  
Material Parameters ◽  
C Elegans ◽  
Physical Mechanisms ◽  
Ring Assembly ◽  
Quantitative Level ◽  
Flow Alignment

Cytokinesis in eukaryotic cells is often accompanied by actomyosin cortical flow. Over 30 years ago, Borisy and White proposed that cortical flow converging upon the cell equator compresses the actomyosin network to mechanically align actin filaments. However, actin filaments also align via search-and-capture, and to what extent compression by flow or active alignment drive furrow formation remains unclear. Here, we quantify the dynamical organization of actin filaments at the onset of ring assembly in the C. elegans zygote, and provide a framework for determining emergent actomyosin material parameters by the use of active nematic gel theory. We characterize flow-alignment coupling, and verify at a quantitative level that compression by flow drives ring formation. Finally, we find that active alignment enhances but is not required for ring formation. Our work characterizes the physical mechanisms of actomyosin ring formation and highlights the role of flow as a central organizer of actomyosin network architecture.

scholarly journals WTS-1/LATS regulates endocytic recycling by restraining F-actin assembly in a synergistic manner

2021 ◽  
Author(s):  
Hanchong Zhang ◽  
Zihang Cheng ◽  
Wenbo Li ◽  
Jie Hu ◽  
Linyue Zhao ◽  
...  
Keyword(s):  
Actin Polymerization ◽  
Hippo Pathway ◽  
Actin Assembly ◽  
Core Component ◽  
Endocytic Recycling ◽  
Actin Organization ◽  
C Elegans ◽  
The Hippo Pathway ◽  
Homeostatic Mechanisms

The disruption of endosomal actin architecture negatively affects endocytic recycling. However, the underlying homeostatic mechanisms that regulate actin organization during recycling remain unclear. In this study, we identified a synergistic endosomal actin assembly restricting mechanism in C. elegans involving WTS-1/LATS kinase, which is a core component of the Hippo pathway. WTS-1 resides on the sorting endosomes and colocalizes with the actin polymerization regulator PTRN-1/CAMSAPs. We observed an increase in PTRN-1-labeled structures in WTS-1-deficient cells, indicating that WTS-1 can limit the endosomal localization of PTRN-1. Accordingly, the actin overaccumulation phenotype in WTS-1-depleted cells was mitigated by the associated PTRN-1 loss. We further demonstrated that recycling defects and actin overaccumulation in WTS-1-deficient cells were reduced by the overexpression of constitutively active UNC-60A/cofilin(S3A), which aligns with the role of LATS as a positive regulator of cofilin activity. Altogether, our data confirmed previous findings, and we proposed an additional model: WTS-1 acts alongside the UNC-60A/cofilin-mediated actin disassembly to restrict the assembly of endosomal F-actin by curbing PTRN-1 dwelling on endosomes, preserving recycling transport.

scholarly journals Caenorhabditis elegans Intersectin: A Synaptic Protein Regulating Neurotransmission

2007 ◽  
Vol 18 (12) ◽  
pp. 5091-5099 ◽  
Author(s):  
Simon Rose ◽  
Maria Grazia Malabarba ◽  
Claudia Krag ◽  
Anna Schultz ◽  
Hanako Tsushima ◽  
...  
Keyword(s):  
Caenorhabditis Elegans ◽  
Synaptic Vesicle ◽  
Regulatory Role ◽  
Actin Dynamics ◽  
Synaptic Vesicle Recycling ◽  
Multifunctional Protein ◽  
C Elegans ◽  
Vesicle Recycling ◽  
Negative Regulatory Role

Intersectin is a multifunctional protein that interacts with components of the endocytic and exocytic pathways, and it is also involved in the control of actin dynamics. Drosophila intersectin is required for viability, synaptic development, and synaptic vesicle recycling. Here, we report the characterization of intersectin function in Caenorhabditis elegans. Nematode intersectin (ITSN-1) is expressed in the nervous system, and it is enriched in presynaptic regions. The C. elegans intersectin gene (itsn-1) is nonessential for viability. In addition, itsn-1-null worms do not display any evident phenotype, under physiological conditions. However, they display aldicarb-hypersensitivity, compatible with a negative regulatory role of ITSN-1 on neurotransmission. ITSN-1 physically interacts with dynamin and EHS-1, two proteins involved in synaptic vesicle recycling. We have previously shown that EHS-1 is a positive modulator of synaptic vesicle recycling in the nematode, likely through modulation of dynamin or dynamin-controlled pathways. Here, we show that ITSN-1 and EHS-1 have opposite effects on aldicarb sensitivity, and on dynamin-dependent phenotypes. Thus, the sum of our results identifies dynamin, or a dynamin-controlled pathway, as a potential target for the negative regulatory role of ITSN-1.

How do histone modifications contribute to transgenerational epigenetic inheritance in C. elegans?

2020 ◽  
Vol 48 (3) ◽  
pp. 1019-1034 ◽  
Author(s):  
Rachel M. Woodhouse ◽  
Alyson Ashe
Keyword(s):  
Histone Modifications ◽  
Molecular Mechanisms ◽  
Epigenetic Inheritance ◽  
Nematode Caenorhabditis Elegans ◽  
Histone Methyltransferases ◽  
Transgenerational Epigenetic Inheritance ◽  
C Elegans ◽  
Recent Developments ◽  
Gene Regulatory

Gene regulatory information can be inherited between generations in a phenomenon termed transgenerational epigenetic inheritance (TEI). While examples of TEI in many animals accumulate, the nematode Caenorhabditis elegans has proven particularly useful in investigating the underlying molecular mechanisms of this phenomenon. In C. elegans and other animals, the modification of histone proteins has emerged as a potential carrier and effector of transgenerational epigenetic information. In this review, we explore the contribution of histone modifications to TEI in C. elegans. We describe the role of repressive histone marks, histone methyltransferases, and associated chromatin factors in heritable gene silencing, and discuss recent developments and unanswered questions in how these factors integrate with other known TEI mechanisms. We also review the transgenerational effects of the manipulation of histone modifications on germline health and longevity.

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.

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