A Series of Tubes: The C. elegans Excretory Canal Cell as a Model for Tubule Development

Formation and regulation of properly sized epithelial tubes is essential for multicellular life. The excretory canal cell of C. elegans provides a powerful model for investigating the integration of the cytoskeleton, intracellular transport, and organismal physiology to regulate the developmental processes of tube extension, lumen formation, and lumen diameter regulation in a narrow single cell. Multiple studies have provided new understanding of actin and intermediate filament cytoskeletal elements, vesicle transport, and the role of vacuolar ATPase in determining tube size. Most of the genes discovered have clear homologues in humans, with implications for understanding these processes in mammalian tissues such as Schwann cells, renal tubules, and brain vasculature. The results of several new genetic screens are described that provide a host of new targets for future studies in this informative structure.

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CCP1, a tubulin deglutamylase, increases survival of rodent spinal cord neurons following glutamate-induced excitotoxicity

10.1101/2020.09.16.295279 ◽

2020 ◽

Author(s):

Yasmin H. Ramadan ◽

Amanda Gu ◽

Nicole Ross ◽

Sara A. McEwan ◽

Maureen M. Barr ◽

...

Keyword(s):

Spinal Cord ◽

Intracellular Transport ◽

Spinal Cord Injuries ◽

Neuronal Injury ◽

Post Translational Modification ◽

Spinal Cord Neurons ◽

C Elegans ◽

Structural Support ◽

Cytoskeletal Elements

AbstractMicrotubules (MTs) are cytoskeletal elements that provide structural support, establish morphology, and act as roadways for intracellular transport in cells. Neurons extend and must maintain long axons and dendrites to transmit information through the nervous system. Therefore, in neurons, the ability to independently regulate cytoskeletal stability and MT-based transport in different cellular compartments is essential. Post-translational modification of MTs is one mechanism by which neurons can regulate the cytoskeleton.The carboxypeptidase CCP1 negatively regulates post-translational glutamylation of MTs. We previously demonstrated that the CCP1 homolog in C. elegans is important for maintenance of cilia. In mammals, loss of CCP1, and the resulting hyperglutamylation of MTs, causes neurodegeneration. It has long been known that CCP1 expression is activated by neuronal injury; however, whether CCP1 plays a neuroprotective role after injury is unknown. Furthermore, it not yet clear whether CCP1 acts on ciliary MTs in spinal cord neurons.Using an in vitro model of excitotoxic neuronal injury coupled with shRNA-mediated knockdown of CCP1, we demonstrate that CCP1 protects neurons from excitotoxic death. Unexpectedly, excitotoxic injury reduced CCP1 expression in our system, and knockdown of CCP1 did not result in loss or shortening of cilia in cultured spinal cord neurons. Our results suggest that CCP1 acts on axonal and dendritic MTs to promote cytoskeletal rearrangements that support neuroregeneration and that enzymes responsible for glutamylation of MTs might be therapeutically targeted to prevent excitotoxic death after spinal cord injuries.

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Identification of novel synaptonemal complex components in C. elegans

The Journal of Cell Biology ◽

10.1083/jcb.201910043 ◽

2020 ◽

Vol 219 (5) ◽

Cited By ~ 6

Author(s):

Matthew E. Hurlock ◽

Ivana Čavka ◽

Lisa E. Kursel ◽

Jocelyn Haversat ◽

Matthew Wooten ◽

...

Keyword(s):

Caenorhabditis Elegans ◽

Structure Function ◽

Synaptonemal Complex ◽

Genetic Screens ◽

Genetic Redundancy ◽

Homologous Chromosomes ◽

Superresolution Microscopy ◽

C Elegans ◽

Biochemical Identification

The synaptonemal complex (SC) is a tripartite protein scaffold that forms between homologous chromosomes during meiosis. Although the SC is essential for stable homologue pairing and crossover recombination in diverse eukaryotes, it is unknown how individual components assemble into the highly conserved SC structure. Here we report the biochemical identification of two new SC components, SYP-5 and SYP-6, in Caenorhabditis elegans. SYP-5 and SYP-6 are paralogous to each other and play redundant roles in synapsis, providing an explanation for why these genes have evaded previous genetic screens. Superresolution microscopy reveals that they localize between the chromosome axes and span the width of the SC in a head-to-head manner, similar to the orientation of other known transverse filament proteins. Using genetic redundancy and structure–function analyses to truncate C-terminal tails of SYP-5/6, we provide evidence supporting the role of SC in both limiting and promoting crossover formation.

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Syndecan Regulates Cellular Morphogenesis in Cooperation with the Netrin Guidance Pathway and Rho-family GTPases

10.1101/2022.01.13.476274 ◽

2022 ◽

Author(s):

Raphael Dima ◽

Marianne Bah Tahe ◽

Yann A Chabi ◽

Lise Rivollet ◽

Anthony F Arena ◽

...

Keyword(s):

Heparan Sulfate ◽

Cell Types ◽

Cellular Functions ◽

C Elegans ◽

Rho Family Gtpases ◽

Canal Cell ◽

Guidance Receptors ◽

Cell Shapes ◽

Rho Family ◽

Excretory Canal

The establishment of complex cell shapes is essential for specific cellular functions, and thus critical in animal development and physiology. Heparan sulfate proteoglycans (HSPGs) are conserved glycoproteins that regulate interactions between extracellular signals and their receptors, to orchestrate morphogenetic events and elicit cellular responses. Although HSPG-regulated pathways have been implicated in regulating the guidance of neuronal migrations, whether HSPGs regulate earlier aspects of cellular development that dictate cell shape remains unknown. HSPGs consist of a protein core (e.g., Syndecan, Perlecan, Glypican, etc.) with attached heparan sulfate (HS) glycosaminoglycan chains, which are synthesized by glycosyltransferases of the exostosin family. Using mutations in the two C. elegans HS glycosyltransferases genes, rib-1 and rib-2, we reveal that HSPGs control the number of cellular projections in the epithelial excretory canal cell, which can form more than its normal four canals in these mutants. We identify SDN-1/Syndecan as the key HSPG that regulates the number of excretory canal cell projections in a cell-autonomous manner. We also find that Syndecan and guidance receptors for Netrin function in the same pathway to restrict the number of cellular projections. Furthermore, we show that the formation of extra projections in the absence of Syndecan requires the conserved Rho-family GTPases CED-10/Rac and MIG-2/RhoG. Our findings not only contribute to understanding the roles of conserved HSPGs in cellular morphogenetic events, but also reveal the existence of an HSPG-regulated system operating to guarantee that a precise number of cellular projections is established during cell development. Given the evolutionary conservation of developmental mechanisms and the molecules implicated, this work provides information relevant to understanding the cellular and molecular bases of the development of precise cellular morphologies in varied cell types across animals.

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Caenorhabditis elegans germline development requires brap-2

10.7287/peerj.preprints.27176 ◽

2018 ◽

Author(s):

Dayana R D'Amora ◽

Queenie Hu ◽

Monica Pizzardi ◽

Terrance Kubiseski

Keyword(s):

Ubiquitin Ligase ◽

Brood Size ◽

Potential Role ◽

Chromosomal Abnormalities ◽

E3 Ubiquitin Ligase ◽

Retention Factor ◽

Germline Development ◽

C Elegans ◽

Mammalian Tissues

Background. Mutations in C. elegans can produce visible and quantifiable defects in morphology, lifespan, and development. BRAP2/IMP (BRCA1-associated binding protein 2) has been characterized as an E3 ubiquitin ligase, a general cytoplasmic retention factor, a potential scaffold protein, and is found to be widely expressed throughout various mammalian tissues, most highly in testes. However, its role in the development or health of these tissues has not been addressed. Results. The focus of this study is to determine the role of BRAP-2 in C. elegans germline development. We determined that brap-2 mutants display defects in germline morphology and a reduction in brood size. We also found that chromosomal abnormalities and embryonic lethality are elevated in brap-2 mutants following DNA damage, suggesting a potential role for BRAP-2 in facilitating DNA repair. Conclusions. Our findings indicate that BRAP-2 is required for C. elegans germline health and identifies a novel role for BRAP-2 in germline development.

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Caenorhabditis elegans germline development requires brap-2

10.7287/peerj.preprints.27176v1 ◽

2018 ◽

Author(s):

Dayana R D'Amora ◽

Queenie Hu ◽

Monica Pizzardi ◽

Terrance Kubiseski

Keyword(s):

Ubiquitin Ligase ◽

Brood Size ◽

Potential Role ◽

Chromosomal Abnormalities ◽

E3 Ubiquitin Ligase ◽

Retention Factor ◽

Germline Development ◽

C Elegans ◽

Mammalian Tissues

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

Biochemical Society Transactions ◽

10.1042/bst20190944 ◽

2020 ◽

Vol 48 (3) ◽

pp. 1019-1034 ◽

Cited By ~ 1

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.

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Centrosome Aurora A gradient ensures single polarity axis in C. elegans embryos

Biochemical Society Transactions ◽

10.1042/bst20200298 ◽

2020 ◽

Vol 48 (3) ◽

pp. 1243-1253 ◽

Cited By ~ 1

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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Characterization of Caenorhabditis elegans Homologs of the Down Syndrome Candidate Gene DYRK1A

Genetics ◽

10.1093/genetics/163.2.571 ◽

2003 ◽

Vol 163 (2) ◽

pp. 571-580 ◽

Cited By ~ 1

Author(s):

William B Raich ◽

Celine Moorman ◽

Clay O Lacefield ◽

Jonah Lehrer ◽

Dusan Bartsch ◽

...

Keyword(s):

Down Syndrome ◽

Caenorhabditis Elegans ◽

Trisomy 21 ◽

Gene Dosage ◽

Inducible Promoters ◽

C Elegans ◽

Dual Specificity ◽

Specificity Protein

Abstract The pathology of trisomy 21/Down syndrome includes cognitive and memory deficits. Increased expression of the dual-specificity protein kinase DYRK1A kinase (DYRK1A) appears to play a significant role in the neuropathology of Down syndrome. To shed light on the cellular role of DYRK1A and related genes we identified three DYRK/minibrain-like genes in the genome sequence of Caenorhabditis elegans, termed mbk-1, mbk-2, and hpk-1. We found these genes to be widely expressed and to localize to distinct subcellular compartments. We isolated deletion alleles in all three genes and show that loss of mbk-1, the gene most closely related to DYRK1A, causes no obvious defects, while another gene, mbk-2, is essential for viability. The overexpression of DYRK1A in Down syndrome led us to examine the effects of overexpression of its C. elegans ortholog mbk-1. We found that animals containing additional copies of the mbk-1 gene display behavioral defects in chemotaxis toward volatile chemoattractants and that the extent of these defects correlates with mbk-1 gene dosage. Using tissue-specific and inducible promoters, we show that additional copies of mbk-1 can impair olfaction cell-autonomously in mature, fully differentiated neurons and that this impairment is reversible. Our results suggest that increased gene dosage of human DYRK1A in trisomy 21 may disrupt the function of fully differentiated neurons and that this disruption is reversible.

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Syndecan Transmembrane Domain Specifically Regulates Downstream Signaling Events of the Transmembrane Receptor Cytoplasmic Domain

International Journal of Molecular Sciences ◽

10.3390/ijms22157918 ◽

2021 ◽

Vol 22 (15) ◽

pp. 7918

Author(s):

Jisun Hwang ◽

Bohee Jang ◽

Ayoung Kim ◽

Yejin Lee ◽

Joonha Lee ◽

...

Keyword(s):

Transmembrane Domain ◽

Growth Factor Receptor ◽

Cytoplasmic Domain ◽

Nih3t3 Cells ◽

C Elegans ◽

Downstream Signaling ◽

Downstream Effectors ◽

Signaling Events

Despite the known importance of the transmembrane domain (TMD) of syndecan receptors in cell adhesion and signaling, the molecular basis for syndecan TMD function remains unknown. Using in vivo invertebrate models, we found that mammalian syndecan-2 rescued both the guidance defects in C. elegans hermaphrodite-specific neurons and the impaired development of the midline axons of Drosophila caused by the loss of endogenous syndecan. These compensatory effects, however, were reduced significantly when syndecan-2 dimerization-defective TMD mutants were introduced. To further investigate the role of the TMD, we generated a chimera, 2eTPC, comprising the TMD of syndecan-2 linked to the cytoplasmic domain of platelet-derived growth factor receptor (PDGFR). This chimera exhibited SDS-resistant dimer formation that was lost in the corresponding dimerization-defective syndecan-2 TMD mutant, 2eT(GL)PC. Moreover, 2eTPC specifically enhanced Tyr 579 and Tyr 857 phosphorylation in the PDGFR cytoplasmic domain, while the TMD mutant failed to support such phosphorylation. Finally, 2eTPC, but not 2eT(GL)PC, induced phosphorylation of Src and PI3 kinase (known downstream effectors of Tyr 579 phosphorylation) and promoted Src-mediated migration of NIH3T3 cells. Taken together, these data suggest that the TMD of a syndecan-2 specifically regulates receptor cytoplasmic domain function and subsequent downstream signaling events controlling cell behavior.

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Genetic Analysis of the Role of Pol II Holoenzyme Components in Repression by the Cyc8-Tup1 Corepressor in Yeast

Genetics ◽

10.1093/genetics/155.4.1535 ◽

2000 ◽

Vol 155 (4) ◽

pp. 1535-1542 ◽

Cited By ~ 3

Author(s):

Mark Lee ◽

Sukalyan Chatterjee ◽

Kevin Struhl

Keyword(s):

Transcriptional Repression ◽

Detectable Effect ◽

Genetic Screens ◽

Phenotypic Analysis ◽

Histone Tails ◽

Pol Ii ◽

Corepressor Complex ◽

The Individual ◽

Modest Effect

Abstract The Cyc8-Tup1 corepressor complex is targeted to promoters by pathway-specific DNA-binding repressors, thereby inhibiting the transcription of specific classes of genes. Genetic screens have identified mutations in a variety of Pol II holoenzyme components (Srb8, Srb9, Srb10, Srb11, Sin4, Rgr1, Rox3, and Hrs1) and in the N-terminal tails of histones H3 and H4 that weaken repression by Cyc8-Tup1. Here, we analyze the effect of individual and multiple mutations in many of these components on transcriptional repression of natural promoters that are regulated by Cyc8-Tup1. In all cases tested, individual mutations have a very modest effect on SUC2 RNA levels and no detectable effect on levels of ANB1, MFA2, and RNR2. Furthermore, multiple mutations within the Srb components, between Srbs and Sin4, and between Srbs and histone tails affect Cyc8-Tup1 repression to the same modest extent as the individual mutations. These results argue that the weak effects of the various mutations on repression by Cyc8-Tup1 are not due to redundancy among components of the Pol II machinery, and they argue against a simple redundancy between the holoenzyme and chromatin pathways. In addition, phenotypic analysis indicates that, although Srbs8–11 are indistinguishable with respect to Cyc8-Tup1 repression, the individual Srbs are functionally distinct in other respects. Genetic interactions among srb mutations imply that a balance between the activities of Srb8 + Srb10 and Srb11 is important for normal cell growth.

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