1K Papers found (0.011 seconds)

Meng F et al. (2008) FEBS J "A fluorescence energy transfer-based mechanical stress sensor for specific proteins in situ."

Sachs F, Meng F, Suchyna TM

[

FEBS J,

2008]

To measure mechanical stress in real time, we designed a fluorescence resonance energy transfer (FRET) cassette, denoted stFRET, which could be inserted into structural protein hosts. The probe was composed of a green fluorescence protein pair, Cerulean and Venus, linked with a stable alpha-helix. We measured the FRET efficiency of the free cassette protein as a function of the length of the linker, the angles of the fluorophores, temperature and urea denaturation, and protease treatment. The linking helix was stable to 80 degrees C, unfolded in 8 m urea, and rapidly digested by proteases, but in all cases the fluorophores were unaffected. We modified the alpha-helix linker by adding and subtracting residues to vary the angles and distance between the donor and acceptor, and assuming that the cassette was a rigid body, we calculated its geometry. We tested the strain sensitivity of stFRET by linking both ends to a rubber sheet subjected to equibiaxial stretch. FRET decreased proportionally to the substrate strain. The naked cassette expressed well in human embryonic kidney-293 cells and, surprisingly, was concentrated in the nucleus. However, when the cassette was located into host proteins such alpha-actinin, nonerythrocyte spectrin and filamin A, the labeled hosts expressed well and distributed normally in cell lines such as 3T3, where they were stressed at the leading edge of migrating cells and relaxed at the trailing edge. When collagen-19 was labeled near its middle with stFRET, it expressed well in Caenorhabditis elegans, distributing similarly to hosts labeled with a terminal green fluorescent protein, and the worms behaved normally.

Meng F et al. (2022) Virology "Unbiased genetic screen identifies Caenorhabditis elegans genes conserved for nodavirus genome replication."

Yan T, Dahal K, Meng F, Lu R

[

Virology,

2022]

All RNA viruses produce and use RNA-dependent RNA polymerases (RdRPs) for their genome replication. Efficient viral genome replication also requires host factors which often function as co-factors of viral RdRP. To identify host factors required for nodavirus genome replication, we carried out an unbiased genetic screen in Caenorhabditis elegans mutants defective in antiviral RNA interference. This genetic screen utilized a self-replicating GFP-tagged viral replicon, derived from flock house virus, as a reporter for the loss of viral genome replication. Upon completing the screen, 16 candidate alleles were isolated and assigned to 14 candidate genes through genetic complementation. Interestingly, 4 of the candidate genes were also found to be required for the genome replication of Orsay virus, a nodavirus that naturally infects C. elegans. Our unbiased genetic screen therefore has led to the identification of a set of worm genes conserved for nodavirus genome replication.

Meng F et al. (2011) Cell Mol Bioeng "Real Time FRET Based Detection of Mechanical Stress in Cytoskeletal and Extracellular Matrix Proteins."

Lazakovitch E, Meng F, Sachs F, Gronostajski RM, Suchyna TM

[

Cell Mol Bioeng,

2011]

A molecular force sensing cassette (stFRET) was incorporated into actinin, filamin, and spectrin in vascular endothelial cells (BAECs) and into collagen-19 in Caenorhabditis elegans. To estimate the stress sensitivity of stFRET in solution, we used DNA springs. A 60-mer loop of single stranded DNA was covalently linked to the external cysteines of the donor and acceptor. When the complementary DNA was added it formed double stranded DNA with higher persistence length, stretching the linker and substantially reducing FRET efficiency. The probe stFRET detected constitutive stress in all cytoskeletal proteins tested, and in migrating cells the stress was greater at the leading edge than the trailing edge. The stress in actinin, filamin and spectrin could be reduced by releasing focal attachments from the substrate with trypsin. Inhibitors of actin polymerization produced a modest increase in stress on the three proteins suggesting they are mechanically in parallel. Local shear stress applied to the cell with a perfusion pipette showed gradients of stress leading from the site of perfusion. Transgenic C. elegans labeled in collagen-19 produced a behaviorally and anatomically normal animal with constitutive stress in the cuticle. Stretching the worm visibly stretched the probe in collagen showing that we can trace the distribution of mean tissue stress in specific molecules. stFRET is a general purpose dynamic sensor of mechanical stress that can be expressed intracellularly and extracellularly in isolated proteins, cells, tissues, organs and animals.

Meng F et al. (2018) Oxid Med Cell Longev "Gengnianchun Extends the Lifespan of Caenorhabditis elegans via the Insulin/IGF-1 Signalling Pathway."

Fu Y, Wang W, Meng F, Rao Y, Li J

[

Oxid Med Cell Longev,

2018]

Gengnianchun (GNC), a traditional Chinese medicine (TCM), is believed to have beneficial effects on ageing-related diseases, such as antioxidant properties and effects against A-induced toxicity. We previously found that GNC extended the lifespan of Caenorhabditis elegans. However, the mechanism underlying this effect was unclear. In this study, we further explored the mechanisms of GNC using a C. elegans model. GNC significantly increased the lifespan of C. elegans and enhanced oxidative and thermal stress resistance. Moreover, chemotaxis increased after GNC treatment. RNA-seq analysis showed that GNC regulated genes associated with longevity. We also conducted lifespan assays with a series of worm mutants. The results showed that GNC significantly extended the lifespan of several mutant strains, including eat-2 (ad465), rsks-1 (ok1255), and glp-1 (e2144), suggesting that the prolongevity effect of GNC is independent of the function of these genes. However, GNC failed to extend the lifespan of daf-2 (e1370), age-1 (hx546), and daf-16 (mu86) mutant strains. Our findings suggest that GNC extends the lifespan of C. elegans via the insulin/IGF-1 signalling pathway and may be a potential antiageing agent.

Meng F et al. (2017) Evid Based Complement Alternat Med "Gengnianchun, a Traditional Chinese Medicine, Enhances Oxidative Stress Resistance and Lifespan in Caenorhabditis elegans by Modulating daf-16/FOXO."

Wang W, Fu Y, Meng F, Li J

[

Evid Based Complement Alternat Med,

2017]

Objective. Gengnianchun (GNC), a traditional Chinese medicine (TCM), is primarily used to improve declining functions related to aging. In this study, we investigated its prolongevity and stress resistance properties and explored the associated regulatory mechanism using a Caenorhabditis elegans model. Methods. Wild-type C. elegans N2 was used for lifespan analysis and oxidative stress resistance assays. Transgenic animals were used to investigate pathways associated with antioxidative stress activity. The effects of GNC on levels of reactive oxygen species (ROS) and expression of specific genes were examined. Results. GNC-treated wild-type worms showed an increase in survival time under both normal and oxidative stress conditions. GNC decreased intracellular ROS levels by 67.95%. GNC significantly enhanced the oxidative stress resistance of several mutant strains, suggesting that the protective effect of GNC is independent of the function of these genes. However, the oxidative stress resistance effect of GNC was absent in worms with daf-16 mutation. We also found upregulation of daf-16 downstream targets including sod-3 and mtl-1. Conclusions. Our findings suggest that GNC extends the lifespan of C. elegans and enhances its resistance to oxidative stress via a daf-16/FOXO-dependent pathway. This study also provides a feasible method for screening the biological mechanisms of TCMs.

Meng F et al. (2017) Evid Based Complement Alternat Med "A Chinese Herbal Formula, Gengnianchun, Ameliorates -Amyloid Peptide Toxicity in a Caenorhabditis elegans Model of Alzheimer's Disease."

Fu Y, Rao Y, Li J, Wang W, Meng F

[

Evid Based Complement Alternat Med,

2017]

Alzheimer's disease (AD) is an age-related neurodegenerative disorder, and the few drugs that are currently available only treat the symptoms. Traditional medicine or phytotherapy has been shown to protect against AD. In our previous studies, Gengnianchun (GNC), a traditional Chinese medicine formula with a prolongevity effect, protected against A-induced cytotoxicity in pheochromocytoma cells (PC-12 cells) and hippocampal cells. Here, we investigated the effects and possible mechanisms by which GNC protected against A toxicity using transgenic Caenorhabditis elegans CL4176. Our results showed that GNC effectively delayed the A toxicity-triggered body paralysis of CL4176 worms. GNC decreased A by reducing A mRNA levels. Moreover, GNC significantly reduced reactive oxygen species in the AD model worms compared with the controls. In addition, GNC upregulated the daf-16, sod-3, hsp-16.2 genes, and enhanced DAF-16 translocation from the cytoplasm to the nuclei under oxidative stress conditions. GNC treatment of C. elegans strains lacking DAF-16 did not affect the paralysis phenotype. Taken together, these findings suggest that GNC could protect against A-induced toxicity via the DAF-16 pathway in C. elegans. Further studies are required to analyze its effectiveness in more complex animals.

Meng L et al. (2020) Dev Cell "NLR-1/CASPR Anchors F-Actin to Promote Gap Junction Formation."

Yan D, Meng L

[

Dev Cell,

2020]

Gap junctions are present in most tissues and play essential roles in various biological processes. However, we know surprisingly little about the molecular mechanisms underlying gap junction formation. Here, we uncover the essential role of a conserved EGF- and laminin-G-domain-containing protein nlr-1/CASPR in the regulation of gap junction formation in multiple tissues across different developmental stages in C.elegans. NLR-1 is located in the gap junction perinexus, a region adjacent to but not overlapping with gap junctions, and forms puncta before the clusters of gap junction channels appear on the membrane. We show that NLR-1 can directly bind to actin to recruit F-actin networks at the gap junction formation plaque, and the formation of F-actin patches plays a critical role in the assembly of gap junction channels. Our findings demonstrate that nlr-1/CASPR acts as an early stage signal for gap junction formation through anchoring of F-actin networks.

Kipreos ET et al. (2000) Genome Biol "The F-box protein family."

Kipreos ET, Pagano M

[

Genome Biol,

2000]

SUMMARY: The F-box is a protein motif of approximately 50 amino acids that functions as a site of protein-protein interaction. F-box proteins were first characterized as components of SCF ubiquitin-ligase complexes (named after their main components, Skp I, Cullin, and an F-box protein), in which they bind substrates for ubiquitin-mediated proteolysis. The F-box motif links the F-box protein to other components of the SCF complex by binding the core SCF component Skp I. F-box proteins have more recently been discovered to function in non-SCF protein complexes in a variety of cellular functions. There are 11 F-box proteins in budding yeast, 326 predicted in Caenorhabditis elegans, 22 in Drosophila, and at least 38 in humans. F-box proteins often include additional carboxy-terminal motifs capable of protein-protein interaction; the most common secondary motifs in yeast and human F-box proteins are WD repeats and leucine-rich repeats, both of which have been found to bind phosphorylated substrates to the SCF complex. The majority of F-box proteins have other associated motifs, and the functions of most of these proteins have not yet been defined.

Chamberlin HM et al. (1995) Worm Breeder's Gazette "lin-49, An Essential Gene Required For Normal F and U Cells."

Chamberlin HM, Sternberg PW, Baillie DL

[

Worm Breeder's Gazette,

1995]

lin-49, an essential gene required for normal F and U cells

Long T et al. (2018) J Virol "Transgene-assisted genetic screen identifies rsd-6 and novel genes as key components of antiviral RNAi in Caenorhabditis elegans."

Lu R, Long T, Meng F

[

J Virol,

2018]

RNA interference (RNAi) is a widespread antiviral mechanism triggered by virus-produced double-stranded RNAs (dsRNAs). In Caenorhabditis elegans antiviral RNAi involves a RIG-I-like RNA helicase, termed DRH-1 (dicer related RNA helicase 1), that is not required for classical RNAi triggered by artificial dsRNA. Currently, whether antiviral RNAi in C. elegans involves novel factors that are dispensable for classical RNAi remains to be an open question. To address this question, we designed and carried out a genetic screen that aims to identify novel genes involved in worm antiviral RNAi. By introducing extra copies of known antiviral RNAi genes into the reporter worms we managed to reject alleles derived from 4 known antiviral RNAi genes, including DRH-1 coding gene, during the screen. Our genetic screen identified altogether 25 alleles which were assigned to 11 candidate genes and 2 known antiviral RNAi genes through genetic complementation tests. Using mapping-by-sequencing strategy we identified one of the candidate genes as rsd-6, a gene that helps maintain genome integrity through an endogenous gene silencing pathway but was not known to be required for antiviral RNAi. More importantly we found that two of the candidate genes are required for antiviral RNAi targeting Orsay virus, a natural viral pathogen of C. elegans, but dispensable for classical RNAi. Since drh-1 is so far the only antiviral RNAi gene not required for classical RNAi, we believe that our genetic screen led to identification of novel worm genes that may target virus-specific features to function in RNAi.ImportanceIn nematode worms drh-1 detects virus produced double-stranded RNA (dsRNA) thereby to specifically contribute to antiviral RNA silencing. To identify drh-1-like genes with dedicated function in antiviral RNAi we recently carried out a genetic screen that was designed to automatically reject all alleles derived from 4 known antiviral silencing genes, including drh-1 Of the 11 candidate genes identified we found two of them to be required for antiviral silencing targeting a natural viral pathogen of C. elegans, but not for classical RNA silencing triggered by artificial dsRNA. We believe that these two genes are novel components of worm antiviral RNAi, considering the fact that drh-1, the only known antiviral RNAi gene that is dispensable for classical RNAi. This genetic screen also identified rsd-6, a gene that maintains genome integrity under unfavorable condition, as key regulator of worm antiviral silencing, demonstrating an interplay between antiviral immunity and genome integrity maintenance.

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