Darby C et al. (2001) Infect Immun "Mimicry of a G protein mutation by pertussis toxin expression in transgenic Caenorhabditis elegans."

Darby C, Falkow S

[Infect Immun, 2001]

Pathogens produce virulence factors that interact directly with host molecules, but in many cases the host targets are unknown. The genetic and molecular identification of these orphan targets is often not feasible with mammalian experimental models. However, a substantial number of known targets are molecules and pathways that are conserved among eukaryotes, and therefore the use of nonmammalian model hosts to identify orphan targets may prove useful. To demonstrate the feasibility of this approach, we transformed the nematode Caenorhabditis elegans with a gene encoding the catalytic subunit of pertussis toxin (PTX), which in mammals inactivates G(o/i)alpha proteins. Expression of PTX in C. elegans produced phenotypes almost identical to those of a null mutation in the nematode gene encoding G(o/i)alpha. Furthermore, PTX suppressed the phenotype of a constitutively active form of nematode G(o/i)alpha protein. These results indicate that PTX is functional in nematodes and acts specifically on the C. elegans homologue of the mammalian target.

Darby C et al. (1999) Worm Breeder's Gazette "A plague on your worms-- Bacteria of the genus Yersinia inhibit the growth of C. elegans"

Falkow S, Darby C

[Worm Breeder's Gazette, 1999]

Recent work shows that C. elegans is a useful model for pathogenesis by the bacterium Pseudomonas aeruginosa (1-4). We examined whether other pathogenic bacteria might also affect the nematode.

Vinci CR et al. (2007) J Biol Chem "Recognition of age-damaged (R,S)-adenosyl-L-methionine by two methyltransferases in the yeast Saccharomyces cerevisiae."

Vinci CR, Clarke SG

[J Biol Chem, 2007]

The biological methyl donor, S adenosylmethionine (AdoMet), can exist in two diastereoisomeric states with respect to its sulfonium ion. The "S" configuration, (S,S)AdoMet, is the only form that is produced enzymatically as well as the only form used in almost all biological methylation reactions. Under physiological conditions, however, the sulfonium ion can spontaneously racemize to the "R" form, producing (R,S)AdoMet. As of yet, (R,S)AdoMet has no known physiological function and may inhibit cellular reactions. In this study, two enzymes have been found in Saccharomyces cerevisiae that are capable of recognizing (R,S)AdoMet and using it to methylate homocysteine to form methionine. These enzymes are the products of the SAM4 and MHT1 genes, previously identified as homocysteine methyltransferases dependent upon AdoMet and S-methylmethionine respectively. We find here that Sam4 recognizes both (S,S) and (R,S)AdoMet, but its activity is much higher with the R,S form. Mht1 reacts with only the R,S form of AdoMet while no activity is seen with the S,S form. R,S-specific homocysteine methyltransferase activity is also shown here to occur in extracts of Arabidopsis thaliana, Drosophila melanogaster, and Caenorhabditis elegans, but has not been detected in several tissue extracts of Mus musculus. Such activity may function to prevent the accumulation of (R,S)AdoMet in these organisms.

Darby C et al. (2002) Nature "Caenorhabditis elegans: plague bacteria biofilm blocks food intake."

Ghori N, Falkow S, Darby C, Hsu JW

[Nature, 2002]

Bubonic plague is transmitted to mammals, including humans, by the bites of fleas whose digestive tracts are blocked by a mass of the bacterium Yersinia pestis. In these fleas, the plague-causing bacteria are surrounded by an extracellular matrix of unknown composition, and the blockage depends on a group of bacterial genes known as the hmsHFRS operon. Here we show that Y. pestis creates an hmsHFRS-dependent extracellular biofilm to inhibit feeding by the nematode Caenorhabditis elegans.

Fanning S et al. (2018) Mol Cell "Lipidomic Analysis of -Synuclein Neurotoxicity Identifies Stearoyl CoA Desaturase as a Target for Parkinson Treatment."

Lou Y, Haque A, Freyzon Y, Farese RV, Terry-Kantor E, Hofbauer HF, Termine D, Welte MA, Barrasa MI, Imberdis T, Noble T, Lindquist S, Clish CB, Jaenisch R, Pincus D, Nuber S, Sandoe J, Kohlwein SD, Kim TE, Ho GPH, Ramalingam N, Walther TC, Baru V, Selkoe D, Srinivasan S, Landgraf D, Soldner F, Dettmer U, Fanning S, Becuwe M, Newby G

[Mol Cell, 2018]

In Parkinson's disease (PD), -synuclein (S) pathologically impacts the brain, a highly lipid-rich organ. We investigated how alterations in S or lipid/fattyacid homeostasis affect each other. Lipidomic profiling of human S-expressing yeast revealed increases in oleic acid (OA, 18:1), diglycerides, and triglycerides. These findings were recapitulated in rodent and human neuronal models of S dyshomeostasis (overexpression; patient-derived triplication or E46K mutation; E46K mice). Preventing lipid droplet formation or augmenting OA increased S yeast toxicity; suppressing the OA-generating enzyme stearoyl-CoA-desaturase (SCD) was protective. Genetic or pharmacological SCD inhibition ameliorated toxicity in S-overexpressing rat neurons. In a C.elegans model, SCD knockout prevented S-induced dopaminergic degeneration. Conversely, we observed detrimental effects of OA on S homeostasis: in human neural cells, excess OA caused S inclusion formation, which was reversed by SCD inhibition. Thus, monounsaturated fatty acid metabolism is pivotal for S-induced neurotoxicity, and inhibiting SCD represents a novel PD therapeutic approach.

G Alloing et al. (1999) International C. elegans Meeting "Analysis of C. elegans host defense response to bacterial pathogen Pseudomonas aeruginosa"

M Tan, S Mahajan-Miklos, FM Ausubel, R Feinbaum, G Alloing

[International C. elegans Meeting, 1999]

Pathogenic bacteria are one of the major causes of disease in both animals and plants. Despite the specificity of the interaction between a bacterial pathogen and its host, there appear to be a number of common mechanisms underlying the process of disease (1,2). On the host side, it has been demonstrated that plants and animals share a set of defense mechanisms involved in "innate immunity". A signal transduction pathway with similarity to the Drosophila developmental regulatory Toll pathway appears to be critical for innate immunity in flies, mammals and plants (1). The underlying similarities between host/bacterial pathogen interactions suggested that a genetically tractable host/pathogen model could greatly improve our understanding of bacterial diseases in mammalian systems. A host/pathogen model system has been developed utilizing C. elegans and PA14, a clinical isolate of P. aeruginosa that is also virulent in Arabidopsis and mouse models. Depending on the medium used for bacterial growth, PA14 kills worms within 24 hours (Fast Killing or FK) or after a few days (Slow Killing or SK). FK is mediated at least in part by diffusible toxins whereas SK requires an infection-like process (3,4). Characterization of several PA14 mutants that are less pathogenic showed that the two killing processes require different bacterial virulence factors. We are interested in understanding the host response to infection by PA14. Towards this end, we have identified the C. elegans homologs of the Drosophila Toll receptor and Pelle kinase and are studying the role of these proteins in response to PA14 in both FK and SK. In addition, six C. elegans mutants have been isolated that are resistant to FK. We are beginning to map and characterize these mutants. (1) Belvin M.P. and Anderson K.V. (1996) Ann. Rev. Cell Dev. Biol. 12 , 393-416 (2) Finlay B.B and S. Falkow, S. (1997). Mol. Biol. Microbiol. Rev. 61 , 136-169 (3) Mahajan-Miklos, S. et al (1999). Cell 96 , 47-56 (4) Tan, M.-W. et al (1999). PNAS 96 , p715-720

Vandecandelaere I et al. (2017) PLoS One "Metabolic activity, urease production, antibiotic resistance and virulence in dual species biofilms of Staphylococcus epidermidis and Staphylococcus aureus."

Deforce D, Coenye T, Van Nieuwerburgh F, Vandecandelaere I

[PLoS One, 2017]

In this paper, the metabolic activity in single and dual species biofilms of Staphylococcus epidermidis and Staphylococcus aureus isolates was investigated. Our results demonstrated that there was less metabolic activity in dual species biofilms compared to S. aureus biofilms. However, this was not observed if S. aureus and S. epidermidis were obtained from the same sample. The largest effect on metabolic activity was observed in biofilms of S. aureus Mu50 and S. epidermidis ET-024. A transcriptomic analysis of these dual species biofilms showed that urease genes and genes encoding proteins involved in metabolism were downregulated in comparison to monospecies biofilms. These results were subsequently confirmed by phenotypic assays. As metabolic activity is related to acid production, the pH in dual species biofilms was slightly higher compared to S. aureus Mu50 biofilms. Our results showed that S. epidermidis ET-024 in dual species biofilms inhibits metabolic activity of S. aureus Mu50, leading to less acid production. As a consequence, less urease activity is required to compensate for low pH. Importantly, this effect was biofilm-specific. Also S. aureus Mu50 genes encoding virulence-associated proteins (Spa, SplF and Dps) were upregulated in dual species biofilms compared to monospecies biofilms and using Caenorhabditis elegans infection assays, we demonstrated that more nematodes survived when co-infected with S. epidermidis ET-024 and S. aureus mutants lacking functional spa, splF or dps genes, compared to nematodes infected with S. epidermidis ET-024 and wild- type S. aureus. Finally, S. epidermidis ET-024 genes encoding resistance to oxacillin, erythromycin and tobramycin were upregulated in dual species biofilms and increased resistance was subsequently confirmed. Our data indicate that both species in dual species biofilms of S. epidermidis and S. aureus influence each other's behavior, but additional studies are required necessary to elucidate the exact mechanism(s) involved.

Vandecandelaere I et al. (2014) Pathog Dis "Protease production by Staphylococcus epidermidis and its effect on Staphylococcus aureus biofilms."

Coenye T, Vandecandelaere I, Depuydt P, Nelis HJ

[Pathog Dis, 2014]

Due to the resistance of Staphylococcus aureus to several antibiotics, treatment of S. aureus infections is often difficult. As an alternative to conventional antibiotics, the field of bacterial interference is investigated. Staphylococcus epidermidis produces a serine protease (Esp) which inhibits S. aureus biofilm formation and which degrades S. aureus biofilms. In this study, we investigated the protease production of 114 S. epidermidis isolates, obtained from biofilms on endotracheal tubes (ET). Most of the S. epidermidis isolates secreted a mixture of serine, cysteine and metalloproteases. We found a link between high protease production by S. epidermidis and the absence of S. aureus in ET biofilms obtained from the same patient. Treating S. aureus biofilms with the supernatant (SN) of the most active protease producing S. epidermidis isolates resulted in a significant biomass decrease compared to untreated controls, while the number of metabolically active cells was not affected. The effect on the biofilm biomass was mainly due to serine proteases. Staphylococcus aureus biofilms treated with the SN of protease producing S. epidermidis were thinner with almost no extracellular matrix. An increased survival of Caenorhabditis elegans, infected with S. aureus Mu50, was observed when the SN of protease positive S. epidermidis was added.

Kamp F et al. (2010) EMBO J "Inhibition of mitochondrial fusion by -synuclein is rescued by PINK1, Parkin and DJ-1."

Haass C, Hegermann J, Giese A, Eimer S, Kamp F, Lutz AK, Nuscher B, Wender N, Brunner B, Winklhofer KF, Exner N, Beyer K, Bartels T

[EMBO J, 2010]

Aggregation of -synuclein (S) is involved in the pathogenesis of Parkinson's disease (PD) and a variety of related neurodegenerative disorders. The physiological function of S is largely unknown. We demonstrate with in vitro vesicle fusion experiments that S has an inhibitory function on membrane fusion. Upon increased expression in cultured cells and in Caenorhabditis elegans, S binds to mitochondria and leads to mitochondrial fragmentation. In C. elegans age-dependent fragmentation of mitochondria is enhanced and shifted to an earlier time point upon expression of exogenous S. In contrast, siRNA-mediated downregulation of S results in elongated mitochondria in cell culture. S can act independently of mitochondrial fusion and fission proteins in shifting the dynamic morphologic equilibrium of mitochondria towards reduced fusion. Upon cellular fusion, S prevents fusion of differently labelled mitochondrial populations. Thus, S inhibits fusion due to its unique membrane interaction. Finally, mitochondrial fragmentation induced by expression of S is rescued by coexpression of PINK1, parkin or DJ-1 but not the PD-associated mutations PINK1 G309D and parkin 1-79 or by DJ-1 C106A.

El Mouridi, Sonia et al. (2021) MicroPubl Biol

AlHarbi, Sarah, El Mouridi, Sonia, Frkjr-Jensen, Christian

[MicroPubl Biol, 2021]

For El Mouridi, S; AlHarbi, S; Frkjr-Jensen, C (2021). A histamine-gated channel is an efficient negative selection marker for C. elegans transgenesis. microPublication Biology. 10.17912/micropub.biology.000349.