Thieringer HA et al. (1998) East Coast Worm Meeting "TOWARD MOLECULAR IDENTIFICATION OF TWO PROTEINS THAT ARE BELIEVED TO INTERACT WITH THE C. elegans UNC-8 ION CHANNEL"

Thieringer HA, Sahota S, Driscoll MA

[East Coast Worm Meeting, 1998]

unc-8, a C. elegans member of the DEG/ENaC ion channel superfamily, is postulated to encode a subunit of a stretch-gated ion channel that modulates locomotion. Loss-of-function alleles of unc-8 have subtle effects on locomotion that include reduction of both the amplitude and wavelength of the normal sinusoidal track carved in an E. coli lawn by a moving worm. Dominant gain-of-function alleles of unc-8 result in hyperactive channels that cause cell swelling and severe uncoordination of the worm, including an inability to move backwards. A suppressor screen for reversal of this uncoordinated phenotype identified four extragenic mutations, sup-40, sup-41, sup-42, and sup-43 (Genetics, 139: 1261-1272). sup-40 is a dominant suppressor of unc-8(gf) alleles that also suppresses mec-4(d)-induced degeneration of the touch receptor neurons. sup-40(lb130) homozygotes are sterile due to fragile and/or poorly formed eggs which can burst upon movement of the worm. Eggs which do not burst are misshapen and do not progress well through development. Cosmid rescue of the suppression phenotype has proven difficult in our hands and we are presently attempting to rescue the sterile phenotype of sup-40. We will report our progress on the molecular identification of sup-40. sup-43(lb141) is an allele-specific, semi-dominant suppressor of a unc-8(e49). e49 encodes change A586T within the conserved extracellular third cysteine-rich domain of the channel subunit. sup-43(lb141) homozygotes exhibit a mild coiler phenotype, which also includes defects in the normal backward movement of the worm in response to light touch on the head. These phenotypes also appear to be semi-dominant. Through both standard genetic and PCR mapping techniques we have mapped sup-43 to chromosome III and are in the process of fine structure mapping of this allele. In the process of mapping this allele we have found that the sup-43 phenotype is exacerbated in mutants defective in some collagen genes, suggesting an interaction with the extracellular matrix. Our progress toward the molecular identification of this allele will be reported.

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.

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

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

[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.

Thieringer HA et al. (1997) International C. elegans Meeting "Analysis of two suppressor loci of unc-8, a degenerin family member that influences the sinusoidal body wave"

Thieringer HA, Sahota S, Driscoll MA, Shreffler W

[International C. elegans Meeting, 1997]

A recently identified member of the degenerin ion channel family, unc-8 (Neuron,18:107-119) is expressed in several sensory neurons, interneurons and motorneurons of C. elegans. unc-8 gain of function mutations induce severe uncoordination and neuronal swelling. unc-8 null alleles show subtle defects in locomotion, most notably a marked decrease in both the amplitude and wavelength of the tracks carved by the worm in an E. coli lawn. We have speculated that unc-8 is a subunit of a stretch-activated channel that potentiates body turns in response to localized neuronal stretch that occurs during normal sinusoidal movement. The identification of proteins that interact with UNC-8 is essential for understanding the composition and mechanism of action of this ion channel. An extensive suppressor screen of!unc-8(gf) alleles conducted by E. Wolinsky's lab identified four extragenic suppressor loci (Genetics,139:1261-1272). We are presently focusing on the molecular identification of two of these. sup-40(lb130) is a dominant suppressor of unc-8 that also suppresses mec-4(d) induced degeneration of the touch receptor neurons. We have narrowed down the sup-40 locus to one cosmid C29C12, which contains 7 candidate genes. A second suppressor of unc-8, sup-43(lb141) is a recessive allele-specific suppressor of unc-8(e49). We know that e49 encodes change A586T within a conserved extracellular cys-rich domain of the channel. sup43(lb141) by itself causes a mild coiler phenotype and also causes swelling and vacuolization of bodywall muscle cells. We have mapped sup-43 to the vicicnity of lin-7 on the left arm of chromosome II. The allele-specific action of sup-43(lb141) suggests it could interact directly with UNC-8.

Thieringer HA et al. (1999) Curr Top Membr "C. elegans members of the DEG/ENaC channel superfamily: form and function."

Driscoll MA, Sahota S, Thieringer HA, Mano I

[Curr Top Membr, 1999]

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."

Coenye T, Van Nieuwerburgh F, Deforce D, 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.

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

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

[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.

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

Depuydt P, Coenye T, Vandecandelaere I, 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.

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.

Nam K et al. (1997) Mol Cell Biol "Severe growth defect in a Schizosaccharomyces pombe mutant defective in intron lariat degradation."

Devine SE, Boeke JD, Lee G, Nam K, Trambley J

[Mol Cell Biol, 1997]

The cDNAs and genes encoding the intron lariat-debranching enzyme were isolated from the nematode Caenorhabditis elegans and the fission yeast Schizosaccharomyces pombe based on their homology with the Saccharomyces cerevisiae gene. The cDNAs were shown to be functional in an interspecific complementation experiment; they can complement an S. cerevisiae dbr1 null mutant. About 2.5% of budding yeast S. cerevisiae genes have introns, and the accumulation of excised introns in a dbr1 null mutant has little effect on cell growth. In contrast, many S. pombe genes contain introns, and often multiple introns per gene, so that S. pombe is estimated to contain approximately 40 times as many introns as S. cerevisiae. The S. pombe dbr1 gene was disrupted and shown to be nonessential. Like the S. cerevisiae mutant, the S. pombe null mutant accumulated introns to high levels, indicating that intron lariat debranching represents a rate-limiting step in intron degradation in both species. Unlike the S. cerevisiae mutant, the S. pombe dbr1::leu1+ mutant had a severe growth defect and exhibited an aberrant elongated cell shape in addition to an intron accumulation phenotype. The growth defect of the S. pombe dbr1::leu1+ strain suggests that debranching activity is critical for efficient intron RNA degradation and that blocking this pathway interferes with cell growth.