C. elegans has served as a laboratory model organism due to its ease of manipulation and the availability of both forward and reverse genetics. In recent years, efforts to study host-pathogen interactions in C. elegans have increased. For example, analysis of infections by bacteria such as Pseudomonas, Salmonella or Serratia has revealed the existence of innate immune pathways in C. elegans that are also conserved in vertebrates. To date, there has been no natural virus infection reported in C. elegans or C. briggsae. Here we describe evidence of natural virus infection in wild isolates of both C. elegans and C. briggsae. Two highly divergent but related RNA viruses in the family Nodaviridae, tentatively named Orsay nodavirus and Santeuil nodavirus, were detected and their genomes partially sequenced. Infected worm lysates passed through 0.2 um filters could be used to infect uninfected worms, which could be further passaged for many generations. Furthermore, the viruses were subject to processing by the RNAi machinery as evidenced by the detection of virally derived small RNAs. Infection of mutant worms defective in small RNA pathways yielded more robust levels of viral RNA as compared to infection of isogenic N2 reference worms. These data demonstrate that nodaviruses are natural parasites of nematodes in the wild. Further study of the interactions between these viruses and nematodes is likely to provide insight into the natural ecology of nematodes and may reveal novel innate immune mechanisms that respond to viral infection. Overall design: Two small RNA libraries (18-30 nt) from nodavirus-infected and cured C. elegans wild isolate JU1580 were sequenced on the Illumina Genome Analyzer II platform. Samples were treated with tobacco acid pyrophosphatase to allow cloning of small RNA molecules with 5'-triphosphates. Each sample was labelled with a unique four base pair barcode and libraries were multiplexed together with a third library (not included in this submission). The multiplexed libraries were sequenced in triplicate.
Natural and experimental infection of Caenorhabditis nematodes by novel viruses related to nodaviruses.
Subject
View SamplesWe sought to obtain gene signature specific of high oxidative phsophorylation function.
Chemotherapy-Resistant Human Acute Myeloid Leukemia Cells Are Not Enriched for Leukemic Stem Cells but Require Oxidative Metabolism.
Cell line, Treatment
View SamplesIt has been hypothesized that chemotherapy resistant human acute myeloid leukemia (AML) cells are enriched in an immature phenotype, cellular quiescence and leukemic initiating cells (LICs). However, these hypotheses have never been validated completely in vivo. We have developed a physiologically relevant chemotherapeutic approach with cytosine arabinoside AraC using patient-derived xenograft (PDX) models. AraC-treated AML cells are not consistently enriched for either immature cells or quiescent cells. AraC treatment does not enrich for LICs as measured by limiting dilution in secondary transplantations. Rather chemotherapy resistant cells in vivo have high levels of reactive oxygen species (ROS) and a gene signature consistent with oxidative phosphorylation (OXPHOS). Treatment of human HIGH OXPHOS but not LOW OXPHOS AML cell lines showed chemotherapy resistance in vivo, showing that essential mitochondrial functions make significant contributions to AraC resistance in AML. Accordingly, targeting mitochondrial OXPHOS metabolism through the inhibition of mitochondrial protein synthesis, the electron transfer chain or fatty acid oxidation induced an energetic shift towards LOW OXPHOS and strongly enhanced anti-leukemic effects of AraC in AML cells. These results demonstrate that chemotherapy resistance in AML is not necessarily associated with stemness but is highly dependent on a distinct oxidative metabolism, and that the HIGH OXPHOS gene signature is a robust hallmark of the AraC response in PDX and a promising therapeutic avenue to treat AML residual disease.
Chemotherapy-Resistant Human Acute Myeloid Leukemia Cells Are Not Enriched for Leukemic Stem Cells but Require Oxidative Metabolism.
Specimen part, Disease
View SamplesIt has been hypothesized that chemotherapy resistant human acute myeloid leukemia (AML) cells are enriched in an immature phenotype, cellular quiescence and leukemic initiating cells (LICs). However, these hypotheses have never been validated completely in vivo. We have developed a physiologically relevant chemotherapeutic approach with cytosine arabinoside AraC using patient-derived xenograft (PDX) models. AraC-treated AML cells are not consistently enriched for either immature cells or quiescent cells. AraC treatment does not enrich for LICs as measured by limiting dilution in secondary transplantations. Rather chemotherapy resistant cells in vivo have high levels of reactive oxygen species (ROS) and a gene signature consistent with oxidative phosphorylation (OXPHOS). Treatment of human HIGH OXPHOS but not LOW OXPHOS AML cell lines showed chemotherapy resistance in vivo, showing that essential mitochondrial functions make significant contributions to AraC resistance in AML. Accordingly, targeting mitochondrial OXPHOS metabolism through the inhibition of mitochondrial protein synthesis, the electron transfer chain or fatty acid oxidation induced an energetic shift towards LOW OXPHOS and strongly enhanced anti-leukemic effects of AraC in AML cells. These results demonstrate that chemotherapy resistance in AML is not necessarily associated with stemness but is highly dependent on a distinct oxidative metabolism, and that the HIGH OXPHOS gene signature is a robust hallmark of the AraC response in PDX and a promising therapeutic avenue to treat AML residual disease.
Chemotherapy-Resistant Human Acute Myeloid Leukemia Cells Are Not Enriched for Leukemic Stem Cells but Require Oxidative Metabolism.
Specimen part, Disease, Treatment, Subject
View Samples