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International Worm Meeting,
2015]
During the life cycle of parasitic and free-living nematodes, a wide range of biomolecules especially proteinases are continuously excreted or secreted into the environment, contributing to their survival, reproduction, habitat establishment, regulation of host immune system and various other functions. ESPs are active directly at the parasite-host or worm-environment interface and many ESP proteinases are enzymatically active, making them promising drug targets and anti-parasitic vaccine candidates. However, the mechanisms and related pathways are not clear given the complex processes occurring throughout different life stages. Also, whether the parasitic proteinases inherited and evolved whole or partly from free-living ancestral worms in response to parasitism has not been addressed. Thus, the investigation of ESP using C. elegans would provide rich information concerning ESP composition and the activity and substrate specificity of proteinases. Comparison of ESPs with parasitic nematodes might reveal novel functional pathways. We used liquid chromatography (LC)/MS-based proteomics to profile proteins released during in vitro maintenance of C. elegans asynchronous cultures and identified about 235 C. elegans proteins so far. General substrate and class specific substrates were used to test ESP general and cathepsin B-, D-like and collagenase activities. In addition, different culture conditions, for example, temperature, different E. coli diet, dauer-forming condition, were explored to show the adjustments in ESP profile according to environment. Annotation of identified proteins showed that many are metalloproteases, cysteine proteases and other catalytic proteases. Some of these proteases are implicated in the molting cycle, carbohydrate metabolism, growth rate regulation among other biological processes. We plan to use genetic methods to further explore specific functional roles of these ESP proteins. .
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International Worm Meeting,
2019]
Excretory-secretory products (ESP) are first characterized and defined in parasitic nematode proteomics studies as the combination of various biomolecules that are continuously excreted or secreted into the environment throughout the whole life cycle. ESP is particularly interesting to many scientists as anti-parasitic vaccine candidates and promising drug target since large portions of ESP are active enzymes that potentially function directly at the parasite-host or worm-environment interfaces. ESPs are also reported to play pivotal roles in many critical pathways, regulating nematode survival, reproduction, food processing and innate immune response. However, proteomics study using parasitic nematodes as model are limited due to lack of whole genome sequence knowledge and lack of genome-editing tools. Thus the number of ESP identified is limited and many functions of ESP proteins are elucidated. Therefore, we use the most studied nematode, Caenorhabditis elegans, as the model to characterize the composition of excreted/secreted proteins with the help of liquid chromatography (LC)/MS. In summary, we characterized more than 500 proteins with mix-staged worms, including many metalloproteases, cysteine proteases and lysozymes. We first confirmed the representative proteins are secreted/excreted from intestine and hypodermis using GFP tagged expression experiments and signal peptide prediction. With gene ontology analysis, many proteins are indicated to play roles in defending bacteria infection and regulating pathogen susceptibility. We compared the reported Caenorhabditis elegans transcriptomes culturing on different bacteria and pathogens with our ESP data, leading to the identification of a specific group of proteins that are up regulated in response to pathogen instead of bacteria. On the other hand, we compare the published ESPs of parasitic nematodes to C. elegans data. Through protein family analysis, we confirmed the conservation of pathways between species that having drastically different life styles, suggesting C. elegans ESP study can serve as the platform to facilitate nematode studies.
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International Worm Meeting,
2013]
The fatty acid composition of an animal's phospholipids has a great impact on the properties of the membrane including its permeability, fluidity, and susceptibility to damage. In fact, altered membrane makeup has been associated with a number of diseases as well as with natural aging. The membrane's integrity is also heavily influenced by its capacity to remove or repair damage; however, little is known about how membrane maintenance mechanisms impact membrane quality over time. Using dietary stable isotope tracers in C. elegans, we can quantify fatty acid replacement in membranes by following the dietary carbon into phospholipids via gas chromatography/mass spectrometry. These studies have found that in young sterile adults about a third of the membrane fatty acids are replaced or remodeled within a 6 hour period. This significant amount of new fatty acid indicates that the membrane needs a continual infusion of new lipids for replacement of consumed and damaged molecules. Additionally, we have found that, in these young adults, the majority of the new fatty acid tails are directly derived from dietary fat. Currently, we are defining how other metabolic pathways such as lipid synthesis influence the maintenance of membranes by conducting a targeted RNAi screen in conjunction with stable isotope labeling. Over aging, the composition of the membrane changes with a specific loss of polyunsaturated fatty acid species. This loss is predicted to be a result of damage as this group of fatty acids is particularly susceptible to reactive oxygen species attack. We hypothesized that reduced membrane maintenance may contribute to the altered membrane structure observed with natural aging. Indeed, we have found that as nematodes age, the amount of dietary resources funneled into the membrane is dramatically reduced. We are currently examining the relationship between membrane maintenance and longevity in different genetic backgrounds. This effort combined with our studies in young adult populations will allow us to identify important regulatory pathways for the maintenance of appropriate membrane composition and to further understand the role of membrane maintenance in aging.
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Neuron,
2012]
The adult mammalian central nervous system exhibits restricted regenerative potential. Chen etal. (2011) and El Bejjani and Hammarlund (2012) used Caenorhabditis elegans to uncover intrinsic factors that inhibit regeneration of axotomized mature neurons, opening avenues for potential therapeutics.
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Immunity,
2017]
IL-17 is a cytokine known primarily for its role in inflammation. In a recent issue of Nature, Chen etal. (2017) demonstrate that IL-17 plays a neuromodulatory role in Caenorhabditis elegans by acting directly on neurons to amplify neuronal responses to stimuli and produce changes in animal behavior.
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Neuron,
2012]
Animals use a form of sensory feedback termed proprioception to monitor their body position and modify the motor programs that control movement. In this issue of Neuron, Wen etal. (2012) provide evidence that a subset of motor neurons function as proprioceptors in C.elegans, where B-type motor neurons sense body curvature to control the bending movements that drive forward locomotion.
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[
International Worm Meeting,
2013]
Gene expression studies not only inform us on potential gene function but also serve as a measure of cellular and organismal phenotype and provide the foundation for building transcriptional regulatory networks. WormBase offers extensive coverage of C. elegans gene expression from small-scale as well as genome-scale studies such as modENCODE. WormBase includes data from expression results based on reporter gene analysis, immunostaining, in situ hybridization, single molecule FISH (smFISH), RNAseq, and microarrays, among others. Recently, we have started to curate gene expression data from other species. Over the past four years WormBase has adapted SPELL as a tool to access large-scale gene expression data. These now include microarray, tiling array, and RNAseq data. The WormBase implementations of SPELL include the following functions: 1. A display of expression levels of individual genes in each experimental dataset. 2. A search capability for genes with similar expression profiles and biological processes. 3. Access to whole experiment datasets, which are available for download. All SPELL microarray, tiling array and RNAseq data are mapped to the current WormBase release, keeping these data current with the latest gene models. Transcriptional regulation information is captured from reported changes in gene expression due to gene mutation, small molecule/chemical, or heat shock/physical treatment. These data can be viewed as part of gene interaction networks using Cytoscape as an interactive browser. In addition, WormBase accommodates a number of canonical transcriptional factor binding sites using Position Weight Matrix (PWM)/Position Frequency Matrix (PFM) data obtained through literature curation. These data can be accessed with the MotifFinder plugin in GBrowse. Large-scale transcriptional regulation data from modEncode, such as ChIp-seq, transcription factor binding sites (enhancers, silencers, promoters), histone modification sites, and DNAseI hypersensitivity sites, etc., are also integrated into WormBase. These data can also be viewed with GBrowse in their own track. In this poster we will give an overview of the gene expression and regulation data and the ways to access and mine these data.
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Dev Cell,
2016]
Temperature-sensing neurons in C.elegans reduce the life-shortening effects of high temperatures via steroid signaling. In this issue of Developmental Cell, Chen etal. (2016) elucidate the underlying mechanisms by which the transcription factor CREB induces the neuropeptide FLP-6 in the temperature-sensing neurons to counteract the life-shortening effects of high temperature.
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Cell,
2014]
Surface receptors can link binding of ligands to changes in the actin-based cell cytoskeleton. Chia etal. and Chen etal. provide evidence for direct binding between the cytoplasmic tails ofreceptorsand the WAVE complex, a regulator of the actin nucleator Arp2/3 complex, which mighthelp to explain how environmental signals are translated into changes in morphology andmotility.
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Mol Neurodegener,
2015]
The original version of this article [1] unfortunately contained a mistake. The author list contained a spelling error for the author Hannah V. McCue. The original article has been corrected for this error. The corrected author list is given below:Xi Chen, Hannah V. McCue, Shi Quan Wong, Sudhanva S. Kashyap, Brian C. Kraemer, Jeff W. Barclay, Robert D. Burgoyne and Alan Morgan