ABSTRACT
During neurodegenerative disease, the toxic accumulation of aggregates and misfolded proteins is often accompanied with widespread changes in peripheral metabolism, even in cells in which the aggregating protein is not present. The mechanism by which the central nervous system elicits a distal reaction to proteotoxic stress remains unknown. We hypothesized that the endocrine communication of neuronal stress plays a causative role in the changes in mitochondrial homeostasis associated with proteotoxic disease states. We find that an aggregation-prone protein expressed in the neurons of C. elegans binds to mitochondria, eliciting a global induction of a mitochondrial-specific unfolded protein response (UPR(mt)), affecting whole-animal physiology. Importantly, dense core vesicle release and secretion of the neurotransmitter serotonin is required for the signal's propagation. Collectively, these data suggest the commandeering of a nutrient sensing network to allow for cell-to-cell communication between mitochondria in response to protein folding stress in the nervous system.
Subject(s)
Homeostasis , Signal Transduction , Unfolded Protein Response , Animals , Caenorhabditis elegans/metabolism , Caenorhabditis elegans Proteins/metabolism , Calcium-Binding Proteins/metabolism , Cell Communication , Mitochondria/metabolism , Neuroendocrine Cells/metabolism , Neurons/metabolism , Neurons/pathology , Peptides/metabolism , Protein Folding , Serotonin/metabolismABSTRACT
BACKGROUND: Embryonic diapause (dormancy) is a state of temporary arrest of embryonic development that is triggered by unfavorable conditions and serves as an evolutionary strategy to ensure reproductive survival. Unlike maternally-controlled embryonic diapause in mammals, chicken embryonic diapause is critically dependent on the environmental temperature. However, the molecular control of diapause in avian species remains largely uncharacterized. In this study, we evaluated the dynamic transcriptomic and phosphoproteomic profiles of chicken embryos in pre-diapause, diapause, and reactivated states. RESULTS: Our data demonstrated a characteristic gene expression pattern in effects on cell survival-associated and stress response signaling pathways. Unlike mammalian diapause, mTOR signaling is not responsible for chicken diapause. However, cold stress responsive genes, such as IRF1, were identified as key regulators of diapause. Further in vitro investigation showed that cold stress-induced transcription of IRF1 was dependent on the PKC-NF-κB signaling pathway, providing a mechanism for proliferation arrest during diapause. Consistently, in vivo overexpression of IRF1 in diapause embryos blocked reactivation after restoration of developmental temperatures. CONCLUSIONS: We concluded that embryonic diapause in chicken is characterized by proliferation arrest, which is the same with other spices. However, chicken embryonic diapause is strictly correlated with the cold stress signal and mediated by PKC-NF-κB-IRF1 signaling, which distinguish chicken diapause from the mTOR based diapause in mammals.
Subject(s)
Diapause , NF-kappa B , Animals , Chick Embryo , Female , Chickens/genetics , Signal Transduction , Temperature , TOR Serine-Threonine KinasesABSTRACT
A set of high-quality pan-genomes would help identify important genes that are still hidden/incomplete in bird reference genomes. In an attempt to address these issues, we have assembled a de novo chromosome-level reference genome of the Silkie (Gallus gallus domesticus), which is an important avian model for unique traits, like fibromelanosis, with unclear genetic foundation. This Silkie genome includes the complete genomic sequences of well-known, but unresolved, evolutionarily, endocrinologically, and immunologically important genes, including leptin, ovocleidin-17, and tumor-necrosis factor-α. The gap-less and manually annotated MHC (major histocompatibility complex) region possesses 38 recently identified genes, with differentially regulated genes recovered in response to pathogen challenges. We also provide whole-genome methylation and genetic variation maps, and resolve a complex genetic region that may contribute to fibromelanosis in these animals. Finally, we experimentally show leptin binding to the identified leptin receptor in chicken, confirming an active leptin ligand-receptor system. The Silkie genome assembly not only provides a rich data resource for avian genome studies, but also lays a foundation for further functional validation of resolved genes.
Subject(s)
Chickens , Leptin , Animals , Chickens/genetics , Leptin/genetics , Genome , Genomics , ChromosomesABSTRACT
The ability to detect, respond and adapt to mitochondrial stress ensures the development and survival of organisms. Caenorhabditis elegans responds to mitochondrial stress by activating the mitochondrial unfolded protein response (UPRmt) to buffer the mitochondrial folding environment, rewire the metabolic state, and promote innate immunity and lifespan extension. Here we show that HDA-1, the C. elegans ortholog of mammalian histone deacetylase (HDAC) is required for mitochondrial stress-mediated activation of UPRmt. HDA-1 interacts and coordinates with the genome organizer DVE-1 to induce the transcription of a broad spectrum of UPRmt, innate immune response and metabolic reprogramming genes. In rhesus monkey and human tissues, HDAC1/2 transcript levels correlate with the expression of UPRmt genes. Knocking down or pharmacological inhibition of HDAC1/2 disrupts the activation of the UPRmt and the mitochondrial network in mammalian cells. Our results underscore an evolutionarily conserved mechanism of HDAC1/2 in modulating mitochondrial homeostasis and regulating longevity.
Subject(s)
Caenorhabditis elegans Proteins/metabolism , Caenorhabditis elegans/enzymology , Histone Deacetylase 1/metabolism , Histone Deacetylase 2/metabolism , Histone Deacetylases/metabolism , Longevity , Mitochondria/enzymology , Animals , Caenorhabditis elegans/genetics , Caenorhabditis elegans/growth & development , Caenorhabditis elegans Proteins/genetics , Histone Deacetylase 1/genetics , Histone Deacetylase 2/genetics , Histone Deacetylases/genetics , Macaca mulatta , Stress, Physiological , Unfolded Protein ResponseABSTRACT
N6-methyldeoxyadenine (6mA), a major type of DNA methylation in bacteria, represents a part of restriction-modification systems to discriminate host genome from invader DNA1. With the recent advent of more sensitive detection techniques, 6mA has also been detected in some eukaryotes2-8. However, the physiological function of this epigenetic mark in eukaryotes remains elusive. Heritable changes in DNA 5mC methylation have been associated with transgenerational inheritance of responses to a high-fat diet9, thus raising the exciting possibility that 6mA may also be transmitted across generations and serve as a carrier of inheritable information. Using Caenorhabditis elegans as a model, here we report that histone H3K4me3 and DNA 6mA modifications are required for the transmission of mitochondrial stress adaptations to progeny. Intriguingly, the global DNA 6mA level is significantly elevated following mitochondrial perturbation. N6-methyldeoxyadenine marks mitochondrial stress response genes and promotes their transcription to alleviate mitochondrial stress in progeny. These findings suggest that 6mA is a precisely regulated epigenetic mark that modulates stress response and signals transgenerational inheritance in C. elegans.
Subject(s)
Adaptation, Physiological , Adenosine/analogs & derivatives , Epigenesis, Genetic , Mitochondria/metabolism , Signal Transduction/genetics , Adenosine/metabolism , Animals , Caenorhabditis elegans/genetics , Caenorhabditis elegans/metabolism , DNA Methylation , Gene Expression Regulation , Histones/metabolism , Mitochondria/genetics , Models, Genetic , Stress, PhysiologicalABSTRACT
Metformin, a widely used first-line drug for treatment of type 2 diabetes (T2D), has been shown to extend lifespan and delay the onset of age-related diseases. However, its primary locus of action remains unclear. Using a pure in vitro reconstitution system, we demonstrate that metformin acts through the v-ATPase-Ragulator lysosomal pathway to coordinate mTORC1 and AMPK, two hubs governing metabolic programs. We further show in Caenorhabditis elegans that both v-ATPase-mediated TORC1 inhibition and v-ATPase-AXIN/LKB1-mediated AMPK activation contribute to the lifespan extension effect of metformin. Elucidating the molecular mechanism of metformin regulated healthspan extension will boost its therapeutic application in the treatment of human aging and age-related diseases.
Subject(s)
Caenorhabditis elegans/drug effects , Caenorhabditis elegans/physiology , Hypoglycemic Agents/metabolism , Lysosomes/metabolism , Metformin/metabolism , AMP-Activated Protein Kinases/metabolism , Animals , Longevity/drug effects , Mechanistic Target of Rapamycin Complex 1/metabolismABSTRACT
Neurons have a central role in the systemic coordination of mitochondrial unfolded protein response (UPRmt) and the cell non-autonomous modulation of longevity. However, the mechanism by which the nervous system senses mitochondrial stress and communicates to the distal tissues to induce UPRmt remains unclear. Here we employ the tissue-specific CRISPR-Cas9 approach to disrupt mitochondrial function only in the nervous system of Caenorhabditis elegans, and reveal a cell non-autonomous induction of UPRmt in peripheral cells. We further show that a neural sub-circuit composed of three types of sensory neurons, and one interneuron is required for sensing and transducing neuronal mitochondrial stress. In addition, neuropeptide FLP-2 functions in this neural sub-circuit to signal the non-autonomous UPRmt. Taken together, our results suggest a neuropeptide coordination of mitochondrial stress response in the nervous system.