Project description:When an organism encounters a pathogen, the host innate immune system is activated to defend against pathogen colonization and the toxic xenobiotics produced. C. elegans employ multiple defense systems to ensure survival when exposed to Pseudomonas aeruginosa (PA14) including activation of the cytoprotective transcription factor SKN-1/NRF2. Although wildtype C. elegans quickly learn to avoid pathogens, here we describe a peculiar apathy to PA14 in animals with constitutive activation of SKN-1, whereby animals choose not to leave while continuing to feed on the pathogen even when a non-pathogenic food option is available. Although lacking the urgency to escape the infectious environment, animals with constitutive SKN-1 activity are not oblivious to the presence of the pathogen and display a typical intestinal distension from PA14 colonization and eventual demise, but surprisingly, fail to learn to avoid pathogen with training. SKN-1 activation, specifically in neurons and intestinal tissues, orchestrates a unique transcriptional program which leads to defects in serotonin signaling from both neurons and non-neuronal tissues that drives the pathogen apathy behavior and pleiotropic responses to selective serotonin reuptake inhibitors (SSRIs). Taken together, our work reveals new insights into how animals perceive environmental pathogens and subsequently alter behavior and cellular programs to promote survival.
Project description:Optimal health requires perpetual transcriptional fidelity of gene expression. SKN-1/NRF2 is a cytoprotective transcription factor in C. elegans that regulates the expression of cellular defenses during stress, including: nutrient deprivation, redox imbalance, and xenobiotic and pathogen exposure. Constitutive activation of SKN-1 results in pleiotropic outcomes, including shortened lifespan and protective redistribution of somatic fat to the germline. We measured lipid distribution between the soma and germ tissues after manipulation of SKN-1 activity. Modulating the epigenetic landscape refines SKN-1 activity away from innate immunity targets and alleviates negative metabolic outcomes. Similarly, paraquat exposure redirects SKN-1 activity toward oxidative stress responses and away from pathogen response genes, which restores lipid distribution across tissues. Lastly, activating p38 MAPK signaling is sufficient to drive SKN-1-dependent loss of somatic fat. These data reveal a coordination of organismal metabolic homeostasis with pathogen responses and identifies mechanisms for counteracting the pleiotropic consequences of aberrant transcriptional activity.
Project description:In the presence of stressful environments, the SKN-1 cytoprotective transcription factor is activated to induce the expression of gene targets that can restore homeostasis. However, constitutive activation of SKN-1 results in diminished health and a reduction of lifespan. Here we demonstrate the necessity to regulate the activity of SKN-1 for maintaining the longevity promoting responses associated with impaired daf-2/insulin receptor signaling, the eat-2 model of caloric restriction, and glp-1-dependent loss of germ cell proliferation. A hallmark of animals with constitutive SKN-1 activation is the age-dependent loss of somatic lipids and this phenotype is linked to the general reduction in survival in animals harboring the skn-1gf allele, but surprisingly, daf-2lf; skn-1gf double mutant animals do not redistribute somatic lipids which suggests the insulin signaling pathway functions downstream of SKN-1 in the maintenance of lipid distribution. As expected, eat-2lf; skn-1gf double mutant animals, which independently activate SKN-1, continue to display somatic lipid depletion in older ages with and without the skn-1gf activating mutation but animals lacking a proliferating germline do not redistribute somatic lipids, which supports a genetic model where SKN-1 activity is an important regulator of lipid mobilization in response to food availability to fuel the developing germline by engaging the daf-2/insulin receptor pathway.
Project description:Coordination of cellular responses to stress are essential for health across the lifespan. The transcription factor SKN-1 is an essential homeostat that mediates survival in stress-inducing environments and cellular dysfunction, but constitutive activation of SKN-1 drives premature aging thus revealing the importance of turning off cytoprotective pathways. Here we identify how SKN-1 activation in two ciliated ASI neurons in C. elegans results in an increase in organismal transcriptional capacity that drives pleiotropic outcomes in peripheral tissues. An increase in the expression of established SKN-1 stress response and lipid metabolism gene classes of RNA in the ASI neurons, in addition to the increased expression of several classes of non-coding RNA, define a molecular signature of animals with constitutive SKN-1 activation and diminished healthspan. We reveal neddylation as a novel regulator of the SKN-1 homeostat that mediates SKN-1 abundance within intestinal cells. Moreover, RNAi-independent activity of the dicer-related DExD/H-box helicase, drh-1, in the intestine, can oppose the effects of aberrant SKN-1 transcriptional activation and delays age-dependent decline in health. Taken together, our results uncover a cell non-autonomous circuit to maintain organism-level homeostasis in response to excessive SKN-1 transcriptional activity in the sensory nervous system.
Project description:Coordination of cellular responses to stress are essential for health across the lifespan. The transcription factor SKN-1 is an essential homeostat that mediates survival in stress-inducing environments and cellular dysfunction, but constitutive activation of SKN-1 drives premature aging thus revealing the importance of turning off cytoprotective pathways. Here we identify how SKN-1 activation in two ciliated ASI neurons in C. elegans results in an increase in organismal transcriptional capacity that drives pleiotropic outcomes in peripheral tissues. An increase in the expression of established SKN-1 stress response and lipid metabolism gene classes of RNA in the ASI neurons, in addition to the increased expression of several classes of non-coding RNA, define a molecular signature of animals with constitutive SKN-1 activation and diminished healthspan. We reveal neddylation as a novel regulator of the SKN-1 homeostat that mediates SKN-1 abundance within intestinal cells. Moreover, RNAi-independent activity of the dicer-related DExD/H-box helicase, drh-1, in the intestine, can oppose the effects of aberrant SKN-1 transcriptional activation and delays age-dependent decline in health. Taken together, our results uncover a cell non-autonomous circuit to maintain organism-level homeostasis in response to excessive SKN-1 transcriptional activity in the sensory nervous system.
Project description:Deficiency of Serotonin Receptor 6 (5-HT6R) or/and its constitutive activity leads to the reduced neurogenesis and the depression-like behavior
Project description:Analysis of gastrocnemius from male wild type(WT) and Skn-1-deficient mice. Skn-1-deficient mice have reduced body weight with low body fat due to increased energy expenditure. Results provide insight into the molecular mechanisms up-regulating metabolism.
Project description:The Caenorhabditis elegans oxidative stress response transcription factor, SKN-1, is essential for the maintenance of redox homeostasis and is a functional ortholog of the Nrf family of transcription factors. The numerous levels of regulation that govern these transcription factors underscore their importance. Here, we add a thioredoxin, encoded by trx-1, to the expansive list of SKN-1 regulators. We report that loss of trx-1 promotes nuclear localization of intestinal SKN-1 in a redox-independent, cell non-autonomous fashion from the ASJ neurons. Furthermore, this regulation is not general to the thioredoxin family, as two other C. elegans thioredoxins TRX-2 and TRX-3 do not play a role in this process. Moreover, TRX-1-dependent regulation requires signaling from the p38 MAPK signaling pathway. However, while TRX-1 regulates SKN-1 nuclear localization, SKN-1 transcriptional activity remains largely unaffected. Interestingly, RNA-Seq revealed that loss of trx-1 elicits a general, organism-wide down-regulation of several classes of genes; those encoding for collagens and lipid transport and localization being most prevalent. However, one prominent lipase-related gene, lips-6, is highly up regulated upon loss of trx-1 in a skn-1-dependent manner. Together, these results uncover a novel role for a thioredoxin in regulating intestinal SKN-1 nuclear localization in a cell non-autonomous manner, thereby contributing to the understanding of the processes involved in maintaining redox homeostasis throughout an organism. Four samples were analyzed: Two nematode strains were analyzed, each under non-stressed and stressed (10mM NaAs) conditions
Project description:modENCODE_submission_2622 This submission comes from a modENCODE project of Michael Snyder. For full list of modENCODE projects, see http://www.genome.gov/26524648 Project Goal: We are identifying the DNA binding sites for 300 transcription factors in C. elegans. Each transcription factor gene is tagged with the same GFP fusion protein, permitting validation of the gene's correct spatio-temporal expression pattern in transgenic animals. Chromatin immunoprecipitation on each strain is peformed using an anti-GFP antibody, and any bound DNA is deep-sequenced using Solexa GA2 technology. For data usage terms and conditions, please refer to http://www.genome.gov/27528022 and http://www.genome.gov/Pages/Research/ENCODE/ENCODEDataReleasePolicyFinal2008.pdf EXPERIMENT TYPE: CHIP-seq. BIOLOGICAL SOURCE: Strain: OP178(made_by : S Kim tags : GFP::3xFlag mutagen : Bombard outcross : 3 genotype : unc119(ed3);wgIs178(skn-1::TY1 EGFP FLAG;unc119) official name : WBGene00004804 ); Developmental Stage: fed L1; Genotype: unc119(ed3);wgIs178(skn-1::TY1 EGFP FLAG;unc119); Sex: Hermaphrodite; EXPERIMENTAL FACTORS: Developmental Stage fed L1; Target gene skn-1; Strain OP178(made_by : S Kim tags : GFP::3xFlag mutagen : Bombard outcross : 3 genotype : unc119(ed3);wgIs178(skn-1::TY1 EGFP FLAG;unc119) official name : WBGene00004804 ); temp (temperature) 20 degree celsius Series_type: CHIP-seq