Mechanisms of epigenetic regulation by C. elegans nuclear RNA interference pathways

The plexin family transmembrane proteins are putative receptors for semaphorins, which are implicated in the morphogenesis of animal embryos, including axonal guidance. We have generated and characterized putative null mutants of the C. elegans plexinA gene, plx-1. plx-1 mutants exhibited morphological defects: displacement of ray 1 and discontinuous alae. The epidermal precursors for the affected organs were aberrantly arranged in the mutants, and a plx-1::gfp transgene was expressed in these epidermal precursor cells as they underwent dynamic morphological changes. Suppression of C. elegans transmembrane semaphorins, Ce-Sema-1a and Ce-Sema-1b, by RNA interference caused a displacement of ray 1 similar to that of plx-1 mutants, whereas mutants for the Ce-Sema-2a/mab-20 gene, which encodes a secreted-type semaphorin, exhibited phenotypes distinct from those of plx-1 mutants. A heterologous expression system showed that Ce-Sema-1a, but not Ce-Sema-2a, physically bound to PLX-1. Our results indicate that PLX-1 functions as a receptor for transmembrane-type semaphorins, and, though Ce-Sema-2a and PLX-1 both play roles in the regulation of cellular morphology during epidermal morphogenesis, they function rather independently.

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Predictable Transitive RNA Interference Induced by mRNA hairpins in C. elegans

The FASEB Journal ◽

10.1096/fasebj.22.1_supplement.787.2 ◽

2008 ◽

Vol 22 (S1) ◽

Author(s):

Jennifer O'Bier ◽

Jessica Cox ◽

Matthew Doty ◽

Caitlin Schwartz ◽

J. David Rawn ◽

...

Keyword(s):

Rna Interference ◽

C Elegans

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HCP-4/CENP-C Promotes the Prophase Timing of Centromere Resolution by Enabling the Centromere Association of HCP-6 in Caenorhabditis elegans

Molecular and Cellular Biology ◽

10.1128/mcb.25.7.2583-2592.2005 ◽

2005 ◽

Vol 25 (7) ◽

pp. 2583-2592 ◽

Cited By ~ 19

Author(s):

Landon L. Moore ◽

Gerald Stanvitch ◽

Mark B. Roth ◽

David Rosen

Keyword(s):

Rna Interference ◽

Caenorhabditis Elegans ◽

Holocentric Chromosomes ◽

Kinetochore Protein ◽

C Elegans ◽

Kinetochore Assembly ◽

Centromere Protein ◽

Sister Centromere ◽

Microtubule Capture

ABSTRACT Prior to microtubule capture, sister centromeres resolve from one another, coming to rest on opposite surfaces of the condensing chromosome. Subsequent assembly of sister kinetochores at each sister centromere generates a geometry favorable for equal levels of segregation of chromatids. The holocentric chromosomes of Caenorhabditis elegans are uniquely suited for the study of centromere resolution and subsequent kinetochore assembly. In C. elegans, only two proteins have been identified as being necessary for centromere resolution, the kinase AIR-2 (prophase only) and the centromere protein HCP-4/CENP-C. Here we found that the loss of proteins involved in chromosome cohesion bypassed the requirement for HCP-4/CENP-C but not for AIR-2. Interestingly, the loss of cohesin proteins also restored the localization of HCP-6 to the kinetochore. The loss of the condensin II protein HCP-6 or MIX-1/SMC2 impaired centromere resolution. Furthermore, the loss of HCP-6 or MIX-1/SMC2 resulted in no centromere resolution when either nocodazole or RNA interference (RNAi) of the kinetochore protein KNL-1 perturbed spindle-kinetochore interactions. This result suggests that normal prophase centromere resolution is mediated by condensin II proteins, which are actively recruited to sister centromeres to mediate the process of resolution.

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DEPS-1 promotes P-granule assembly and RNA interference in C. elegans germ cells

Development ◽

10.1242/dev.015552 ◽

2008 ◽

Vol 135 (5) ◽

pp. 983-993 ◽

Cited By ~ 49

Author(s):

C. A. Spike ◽

J. Bader ◽

V. Reinke ◽

S. Strome

Keyword(s):

Rna Interference ◽

Germ Cells ◽

C Elegans

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A novel linker histone-like protein is associated with cytoplasmic filaments inCaenorhabditis elegans

Journal of Cell Science ◽

10.1242/jcs.115.14.2881 ◽

2002 ◽

Vol 115 (14) ◽

pp. 2881-2891

Author(s):

Monika A. Jedrusik ◽

Stefan Vogt ◽

Peter Claus ◽

Ekkehard Schulze

Keyword(s):

Rna Interference ◽

Fluorescent Protein ◽

Muscle Growth ◽

Egg Laying ◽

Globular Domain ◽

Protein Fusion ◽

Linker Histones ◽

C Elegans ◽

Fusion Protein Expression ◽

Green Fluorescent

The histone H1 complement of Caenorhabditis elegans contains a single unusual protein, H1.X. Although H1.X possesses the globular domain and the canonical three-domain structure of linker histones, the amino acid composition of H1.X is distinctly different from conventional linker histones in both terminal domains. We have characterized H1.X in C. elegans by antibody labeling, green fluorescent protein fusion protein expression and RNA interference. Unlike normal linker histones, H1.X is a cytoplasmic as well as a nuclear protein and is not associated with chromosomes. H1.X is most prominently expressed in the marginal cells of the pharynx and is associated with a peculiar cytoplasmic cytoskeletal structure therein, the tonofilaments. Additionally H1.X::GFP is expressed in the cytoplasm of body and vulva muscle cells, neurons, excretory cells and in the nucleoli of embryonic blastomeres and adult gut cells. RNA interference with H1.X results in uncoordinated and egg laying defective animals, as well as in a longitudinally enlarged pharynx. These phenotypes indicate a cytoplasmic role of H1.X in muscle growth and muscle function.

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RNA interference in Caenorhabditis elegans: Uptake, mechanism, and regulation

Parasitology ◽

10.1017/s0031182011001788 ◽

2011 ◽

Vol 139 (5) ◽

pp. 560-573 ◽

Cited By ~ 35

Author(s):

JIMMY J. ZHUANG ◽

CRAIG P. HUNTER

Keyword(s):

Rna Interference ◽

Genetic Analysis ◽

Large Scale ◽

Parasitic Nematodes ◽

Loss Of Function ◽

Uptake Mechanism ◽

Delivery Methods ◽

C Elegans ◽

Systemic Rnai ◽

Powerful Research Tool

SUMMARYRNA interference (RNAi) is a powerful research tool that has enabled molecular insights into gene activity, pathway analysis, partial loss-of-function phenotypes, and large-scale genomic discovery of gene function. While RNAi works extremely well in the non-parasitic nematode C. elegans, it is also especially useful in organisms that lack facile genetic analysis. Extensive genetic analysis of the mechanisms, delivery and regulation of RNAi in C. elegans has provided mechanistic and phenomenological insights into why RNAi is so effective in this species. These insights are useful for the testing and development of RNAi in other nematodes, including parasitic nematodes where more effective RNAi would be extremely useful. Here, we review the current advances in C. elegans for RNA delivery methods, regulation of cell autonomous and systemic RNAi phenomena, and implications of enhanced RNAi mutants. These discussions, with a focus on mechanism and cross-species application, provide new perspectives for optimizing RNAi in other species.

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Inducible Systemic RNA Silencing in Caenorhabditis elegans

Molecular Biology of the Cell ◽

10.1091/mbc.e03-01-0858 ◽

2003 ◽

Vol 14 (7) ◽

pp. 2972-2983 ◽

Cited By ~ 86

Author(s):

Lisa Timmons ◽

Hiroaki Tabara ◽

Craig C. Mello ◽

Andrew Z. Fire

Keyword(s):

Rna Interference ◽

Caenorhabditis Elegans ◽

Rna Silencing ◽

Molecular Mechanisms ◽

Normal Animal ◽

Cell Types ◽

Animal Cells ◽

Tissue Specific ◽

C Elegans ◽

Systemic Rna

Introduction of double-stranded RNA (dsRNA) can elicit a gene-specific RNA interference response in a variety of organisms and cell types. In many cases, this response has a systemic character in that silencing of gene expression is observed in cells distal from the site of dsRNA delivery. The molecular mechanisms underlying the mobile nature of RNA silencing are unknown. For example, although cellular entry of dsRNA is possible, cellular exit of dsRNA from normal animal cells has not been directly observed. We provide evidence that transgenic strains of Caenorhabditis elegans transcribing dsRNA from a tissue-specific promoter do not exhibit comprehensive systemic RNA interference phenotypes. In these same animals, modifications of environmental conditions can result in more robust systemic RNA silencing. Additionally, we find that genetic mutations can influence the systemic character of RNA silencing in C. elegans and can separate mechanisms underlying systemic RNA silencing into tissue-specific components. These data suggest that trafficking of RNA silencing signals in C. elegans is regulated by specific physiological and genetic factors.

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mut-7 of C. elegans, Required for Transposon Silencing and RNA Interference, Is a Homolog of Werner Syndrome Helicase and RNaseD

Cell ◽

10.1016/s0092-8674(00)81645-1 ◽

1999 ◽

Vol 99 (2) ◽

pp. 133-141 ◽

Cited By ~ 414

Author(s):

René F Ketting ◽

Thomas H.A Haverkamp ◽

Henri G.A.M van Luenen ◽

Ronald H.A Plasterk

Keyword(s):

Rna Interference ◽

Werner Syndrome ◽

C Elegans ◽

Transposon Silencing

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ATP-binding Cassette Transporters Are Required for Efficient RNA Interference in Caenorhabditis elegans

Molecular Biology of the Cell ◽

10.1091/mbc.e06-03-0192 ◽

2006 ◽

Vol 17 (8) ◽

pp. 3678-3688 ◽

Cited By ~ 33

Author(s):

Prema Sundaram ◽

Benjamin Echalier ◽

Wang Han ◽

Dawn Hull ◽

Lisa Timmons

Keyword(s):

Rna Interference ◽

Caenorhabditis Elegans ◽

Abc Transporters ◽

Transport Systems ◽

Atp Binding ◽

C Elegans ◽

Steep Concentration Gradient ◽

Conserved Gene ◽

Membrane Transport Systems ◽

Atp Binding Cassette

RNA interference (RNAi) is a conserved gene-silencing phenomenon that can be triggered by delivery of double-stranded RNA (dsRNA) to cells and is a widely exploited technology in analyses of gene function. Although a number of proteins that facilitate RNAi have been identified, current descriptions of RNAi and interrelated mechanisms are far from complete. Here, we report that the Caenorhabditis elegans gene haf-6 is required for efficient RNAi. HAF-6 is a member of the ATP-binding cassette (ABC) transporter gene superfamily. ABC transporters use ATP to translocate small molecule substrates across the membranes in which they reside, often against a steep concentration gradient. Collectively, ABC transporters are involved in a variety of activities, including protective or barrier mechanisms that export drugs or toxins from cells, organellar biogenesis, and mechanisms that protect against viral infection. HAF-6 is expressed predominantly in the intestine and germline and is localized to intracellular reticular organelles. We further demonstrate that eight additional ABC genes from diverse subfamilies are each required for efficient RNAi in C. elegans. Thus, the ability to mount a robust RNAi response to dsRNA depends upon the deployment of two ancient systems that respond to environmental assaults: RNAi mechanisms and membrane transport systems that use ABC proteins.

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