Caudy AA et al. (2003) Nature "A micrococcal nuclease homologue in RNAi effector complexes."

Caudy AA, Ketting RF, Hammond SM, Hannon GJ, Denli AM, Myers MM, Silva JM, Plasterk RHA, Bathoorn AMP, Tops BBJ

[Nature, 2003]

RNA interference (RNAi) regulates gene expression by the cleavage of messenger RNA, by mRNA degradation and by preventing protein synthesis. These effects are mediated by a ribonucleoprotein complex known as RISC (RNA-induced silencing complex)(1). We have previously identified four Drosophila components (short interfering RNAs1, Argonaute 2 (ref. 2), VIG and FXR3) of a RISC enzyme that degrades specific mRNAs in response to a double-stranded-RNA trigger. Here we show that Tudor-SN (tudor staphylococcal nuclease)-a protein containing five staphylococcal/micrococcal nuclease domains and a tudor domain-is a component of the RISC enzyme in Caenorhabditis elegans, Drosophila and mammals. Although Tudor-SN contains non-canonical active-site sequences, we show that purified Tudor-SN exhibits nuclease activity similar to that of other staphylococcal nucleases. Notably, both purified Tudor-SN and RISC are inhibited by a specific competitive inhibitor of micrococcal nuclease. Tudor-SN is the first RISC subunit to be identified that contains a recognizable nuclease domain, and could therefore contribute to the RNA

Del Borrello, S. et al. (2017) International Worm Meeting "Using simulated anaerobiosis in C. elegans as a platform for anthelmintic drug discovery."

Schertzberg, M., Spensley, M., Caudy, A. A., Fraser, A. G., Lautens, M. J., Del Borrello, S.

[International Worm Meeting, 2017]

Parasitic helminth infections affect 1 4 of the world, and result in thousands of deaths every year as well as economic losses in agriculture. This is in part due to increasing anthelmintic resistance, thus fueling a need for the discovery of novel anthelmintics. During host infection, parasitic helminths are in an oxygen-deprived environment, during which they use a special form of anaerobic respiration to survive - malate dismutation - which requires rhodoquinone, a ubiquinone-related electron carrier. This pathway is absent in mammals, but exists in the nematode worm C. elegans, making it an ideal drug target and the worm a good model of parasitic helminth metabolism. We established an image-based assay of worm movement-the acute assay-and found that worms treated with potassium cyanide (KCN) become paralyzed, however additional treatment with 2-Deoxy-D-glucose (2DG) recovers movement. KCN prevents oxidative phosphorylation in the aerobic electron transport chain (ETC), and 2DG is a glucose analog that blocks glycolysis. A key question is how worms are producing ATP when both glycolysis and the ETC are blocked. We used RNAseq to investigate the transcriptional response to KCN + 2DG, and found our treatment activates the hypoxia response. Mutant analysis of genes required for this response has shown this response is required for recovery. Furthermore, RNAseq data shows that treatment with KCN + 2DG recapitulates anaerobiosis. Interestingly, we also see inhibition of Complex I with Rotenone prevents recovery. Therefore, we conclude that recovery from paralysis requires at least two processes: a working hypoxia response, and the anaerobic electron transport chain. My project goal is to better understand these and other anaerobic pathways to uncover new anthelmintic targets. Our long-term goals include conducting a drug screen for new anthelmintics using simulated anaerobiosis in C. elegans, and a forward genetic screen to uncover alternative metabolic pathways required for recovery.

Tan, J. et al. (2019) International Worm Meeting "Comparative analysis of gene expression profiles in parasitic helminths to identify novel genes involved in anaerobic metabolism."

Schertzberg, M., Caudy, A., Tan, J., Del Borrello, S., Lautens, M., Doucet, K., Spensley, M., Fraser, A.

[International Worm Meeting, 2019]

Parasitic worms infect over a billion humans worldwide and have a significant destructive impact on agriculture that results in billions of dollars in economic losses. While there are a few existing anthelmintic drugs to treat parasitic infections, increasing resistance to these drugs have accelerated the need to develop new anthelmintics. Our goal is to use C. elegans as a model to understand the alternative metabolic pathways used by parasitic worms to survive in the anaerobic environments of their hosts. In low oxygen conditions helminths and some marine organisms are able to utilize rhodoquinone (RQ) for use as an alternative electron carrier. Since humans do not synthesize RQ or utilize the same form of anaerobic metabolisms, inhibiting crucial components of this pathway is thus an attractive prospect for anthelmintic development. To identify novel genes important for anaerobic metabolism in helminths, we mined existing RNA-seq data to compare gene expression profiles across a range of parasitic worms. In particular, we focused on differential gene expression during the life cycles of these parasites, looking for clusters of genes that are co-expressed during host infection suggesting a role in RQ synthesis and/or anaerobic metabolism. We then use an image-based assay developed in our lab to test the requirement of these genes in anaerobic pathways in C. elegans. Together, this will provide further insight into how these anaerobic pathways are regulated in worms, and help identify potential targets for new anthelmintic drugs.

Wang, Chris et al. (2013) International Worm Meeting "TEG-1 regulates the stability of miRISC components and the levels of microRNAs."

Hansen, Dave, Wang, Chris

[International Worm Meeting, 2013]

TEG-1 (Tumorous Enhancer of Glp-1(gf))-related proteins are found in organisms from yeast to humans. We have previously reported roles for TEG-1 in germline development, including regulating the mitosis/meiosis decision and germline sex determination (Wang et. al. 2012. Dev. Dyn. 241:505-521). Recently, we found that teg-1 mutants display heterochronic defect phenotypes, including: (1) reiteration of the L2 stage resulting in an increased number of seam cells; (2) defective seam cell fusion at the L4 molt; and (3) retarded alae formation at the L4-adult transition. Since developmental timing defects are often controlled by microRNAs, we sought to determine if TEG-1 also plays a role in microRNA function. We found that mature let-7, mir-58, and mir-62 levels are significantly reduced in teg-1 mutants. To gain insight into the cause of reduced microRNA levels in teg-1 mutants, we performed immunoprecipitation (IP) and found that TEG-1 interacts with VIG-1, a Drosophila Vasa Intronic Gene ortholog, whose activity is required for proper let-7 function and is believed to be a component of the microRNA RNA-induced silencing complex (RISC) (Caudy et. al. 2003. Nature 425:411-414; Chan et. al. 2008. RNA 14:2104-2114). This interaction was confirmed by co-IP experiments using wild-type extracts. Interestingly, we also found that TEG-1 levels are lowered in vig-1 mutants, and both VIG-1 and ALG-1 (an Argonaute component of the RISC complex) levels are reduced in teg-1 mutants. This finding led us to propose that VIG-1 and ALG-1 levels are regulated post-translationally. Consistent with this hypothesis, we found that the mRNA levels of vig-1 and alg-1 remain unchanged in teg-1 mutants, whereas elevated VIG-1 and ALG-1 protein levels are detected in teg-1 mutants and wild-type animals treated with lactacystin, a specific inhibitor of the 26S proteasome. Together, these data suggest that TEG-1 regulates a broad range of microRNAs through stabilizing the microRISC components, potentially by protecting them from proteasomal degradation.

Quartey MO et al. (2021) Sci Rep "The A(1-38) peptide is a negative regulator of the A(1-42) peptide implicated in Alzheimer disease progression."

Pennington PR, Heistad RM, Nyarko JNK, Barnes JR, Bolanos MAC, Parsons MP, Knudsen KJ, De Carvalho CE, Leary SC, Mousseau DD, Buttigieg J, Maley JM, Quartey MO

[Sci Rep, 2021]

The pool of -Amyloid (A) length variants detected in preclinical and clinical Alzheimer disease (AD) samples suggests a diversity of roles for A peptides. We examined how a naturally occurring variant, e.g. A(1-38), interacts with the AD-related variant, A(1-42), and the predominant physiological variant, A(1-40). Atomic force microscopy, Thioflavin T fluorescence, circular dichroism, dynamic light scattering, and surface plasmon resonance reveal that A(1-38) interacts differently with A(1-40) and A(1-42) and, in general, A(1-38) interferes with the conversion of A(1-42) to a -sheet-rich aggregate. Functionally, A(1-38) reverses the negative impact of A(1-42) on long-term potentiation in acute hippocampal slices and on membrane conductance in primary neurons, and mitigates an A(1-42) phenotype in Caenorhabditis elegans. A(1-38) also reverses any loss of MTT conversion induced by A(1-40) and A(1-42) in HT-22 hippocampal neurons and APOE 4-positive human fibroblasts, although the combination of A(1-38) and A(1-42) inhibits MTT conversion in APOE 4-negative fibroblasts. A greater ratio of soluble A(1-42)/A(1-38) [and A(1-42)/A(1-40)] in autopsied brain extracts correlates with an earlier age-at-death in males (but not females) with a diagnosis of AD. These results suggest that A(1-38) is capable of physically counteracting, potentially in a sex-dependent manner, the neuropathological effects of the AD-relevant A(1-42).

Danielle Thierry-Mieg et al. (2003) Worm Breeder's Gazette "www.wormgenes.org , a new gene centered database"

Vahan Simonyan, Michel Potdevin, Mark Sienkiewicz, Yuji KOHARA, Jean Thierry-Mieg, Danielle Thierry-Mieg, Tadasu SHIN-I

[Worm Breeder's Gazette, 2003]

Wormgenes is a new resource for C.elegans offering a detailed summary about each gene and a powerful query system.

Tangrodchanapong T et al. (2020) Front Pharmacol "Frondoside A Attenuates Amyloid- Proteotoxicity in Transgenic Caenorhabditis elegans by Suppressing Its Formation."

Tangrodchanapong T, Sobhon P, Meemon K

[Front Pharmacol, 2020]

Oligomeric assembly of Amyloid- (A) is the main toxic species that contribute to early cognitive impairment in Alzheimer's patients. Therefore, drugs that reduce the formation of A oligomers could halt the disease progression. In this study, by using transgenic <i>Caenorhabditis elegans</i> model of Alzheimer's disease, we investigated the effects of frondoside A, a well-known sea cucumber <i>Cucumaria frondosa</i> saponin with anti-cancer activity, on A aggregation and proteotoxicity. The results showed that frondoside A at a low concentration of 1 M significantly delayed the worm paralysis caused by A aggregation as compared with control group. In addition, the number of A plaque deposits in transgenic worm tissues was significantly decreased. Frondoside A was more effective in these activities than ginsenoside-Rg3, a comparable ginseng saponin. Immunoblot analysis revealed that the level of small oligomers as well as various high molecular weights of A species in the transgenic <i>C. elegans</i> were significantly reduced upon treatment with frondoside A, whereas the level of A monomers was not altered. This suggested that frondoside A may primarily reduce the level of small oligomeric forms, the most toxic species of A. Frondoside A also protected the worms from oxidative stress and rescued chemotaxis dysfunction in a transgenic strain whose neurons express A. Taken together, these data suggested that low dose of frondoside A could protect against A-induced toxicity by primarily suppressing the formation of A oligomers. Thus, the molecular mechanism of how frondoside A exerts its anti-A aggregation should be studied and elucidated in the future.

Hodgkin JA (1998) International Journal of Developmental Biology "Seven types of pleiotropy."

Hodgkin JA

[International Journal of Developmental Biology, 1998]

Pleiotropy , a situation in which a single gene influences multiple phenotypic tra its, can arise in a variety of ways. This paper discusses possible underlying mechanisms and proposes a classification of the various phenomena involved.

Tuck S (2011) Curr Biol "Extracellular vesicles: budding regulated by a phosphatidylethanolamine translocase."

Tuck S

[Curr Biol, 2011]

Recent work on a Caenorhabditis elegans transmembrane ATPase reveals a central role for the aminophospholipid phosphatidylethanolamine in the production of a class of extracellular vesicles.

Viney ME et al. (2004) Naturwissenschaften "Is dauer pheromone of Caenorhabditis elegans really a pheromone?"

Viney ME, Franks NR

[Naturwissenschaften, 2004]

Animals respond to signals and cues in their environment. The difference between a signal (e.g. a pheromone) and a cue (e.g. a waste product) is that the information content of a signal is subject to natural selection, whereas that of a cue is not. The model free-living nematode Caenorhabditis elegans forms an alternative developmental morph (the dauer larva) in response to a so-called 'dauer pheromone', produced by all worms. We suggest that the production of 'dauer pheromone' has no fitness advantage for an individual worm and therefore we propose that 'dauer pheromone' is not a signal, but a cue. Thus, it should not be called a pheromone.