Project description:Somatic stem cells mediate tissue maintenance for the lifetime of an organism. Despite the well-established longevity that is a prerequisite for such function, accumulating data argue for compromised stem cell function with age. Identifying the mechanisms underlying age-dependent stem cell dysfunction is therefore key to understand the aging process. Using a model that carries a proofreading defective mitochondrial DNA polymerase, we demonstrate hematopoietic defects reminiscent of premature HSC aging including anemia, lymphopenia and myeloid lineage skewing. However, in contrast to physiologic stem cell aging, rapidly accumulating mitochondrial DNA mutations displayed little involvement of the hematopoietic stem cell pool but rather with distinct differentiation blocks and/or disappearance of downstream progenitors. Hematopoietic stem cells (HSC) has been sorted out from midaged wildtype and mutator mice and compared with stem cells sorted from young and and old wt mice
Project description:Somatic stem cells mediate tissue maintenance for the lifetime of an organism. Despite the well-established longevity that is a prerequisite for such function, accumulating data argue for compromised stem cell function with age. Identifying the mechanisms underlying age-dependent stem cell dysfunction is therefore key to understand the aging process. Using a model that carries a proofreading defective mitochondrial DNA polymerase, we demonstrate hematopoietic defects reminiscent of premature HSC aging including anemia, lymphopenia and myeloid lineage skewing. However, in contrast to physiologic stem cell aging, rapidly accumulating mitochondrial DNA mutations displayed little involvement of the hematopoietic stem cell pool but rather with distinct differentiation blocks and/or disappearance of downstream progenitors.
Project description:Senescence phenotypes and mitochondrial dysfunction are implicated in aging and neurodegeneration, and in the premature aging disease, including A-T. Loss of mitochondrial function can drive age-related decline in the brain, but little is known about whether improving mitochondrial homeostasis alleviates senescence phenotypes. Here we demonstrate impaired mitochondrial function and increased senescence growth arrest with senescence-associated secretory phenotype (SASP) in A-T patient fibroblasts, and in ATM-deficient cells and mice. We find that boosting intracellular NAD+ levels with nicotinamide riboside (NR) reduces senescence, suppresses neuroinflammation, and improves motor function in Atm-/- mice. We further show that the senescence responses are mediated by stimulator of interferon genes (STING), which is activated by cytoplasmic mtDNA and that NR prevents senescence and neuroinflammation through stimulation of mitophagy. Our findings suggest a pivotal role for mitochondrial dysfunction induced senescence in A-T pathogenesis, and that enhancing mitophagy is a potential therapeutic intervention.
Project description:Senescence phenotypes and mitochondrial dysfunction are implicated in aging and neurodegeneration, and in the premature aging disease, including A-T. Loss of mitochondrial function can drive age-related decline in the brain, but little is known about whether improving mitochondrial homeostasis alleviates senescence phenotypes. Here we demonstrate impaired mitochondrial function and increased senescence growth arrest with senescence-associated secretory phenotype (SASP) in A-T patient fibroblasts, and in ATM-deficient cells and mice. We find that boosting intracellular NAD+ levels with nicotinamide riboside (NR) reduces senescence, suppresses neuroinflammation, and improves motor function in Atm-/- mice. We further show that the senescence responses are mediated by stimulator of interferon genes (STING), which is activated by cytoplasmic mtDNA and that NR prevents senescence and neuroinflammation through stimulation of mitophagy. Our findings suggest a pivotal role for mitochondrial dysfunction induced senescence in A-T pathogenesis, and that enhancing mitophagy is a potential therapeutic intervention.
Project description:Although numerous long noncoding RNAs (lncRNAs) have been identified, our understanding of their roles in mammalian physiology remains limited. Here we investigated the physiologic function of the conserved lncRNA Norad in vivo. Deletion of Norad in mice results in genomic instability and mitochondrial dysfunction, leading to a dramatic multi-system degenerative phenotype resembling premature aging. Loss of tissue homeostasis in Norad-deficient animals is attributable to augmented activity of PUMILIO proteins, which act as post-transcriptional repressors of target mRNAs to which they bind. Norad is the preferred RNA target of PUMILIO2 (PUM2) in mouse tissues and, upon loss of Norad, PUM2 hyperactively represses key genes required for mitosis and mitochondrial function. Accordingly, enforced Pum2 expression fully phenocopies Norad deletion, resulting in rapid-onset aging-associated phenotypes. These findings provide new insights and open new lines of investigation into the roles of noncoding RNAs and RNA binding proteins in normal physiology and aging.
Project description:Although numerous long noncoding RNAs (lncRNAs) have been identified, our understanding of their roles in mammalian physiology remains limited. Here we investigated the physiologic function of the conserved lncRNA Norad in vivo. Deletion of Norad in mice results in genomic instability and mitochondrial dysfunction, leading to a dramatic multi-system degenerative phenotype resembling premature aging. Loss of tissue homeostasis in Norad-deficient animals is attributable to augmented activity of PUMILIO proteins, which act as post-transcriptional repressors of target mRNAs to which they bind. Norad is the preferred RNA target of PUMILIO2 (PUM2) in mouse tissues and, upon loss of Norad, PUM2 hyperactively represses key genes required for mitosis and mitochondrial function. Accordingly, enforced Pum2 expression fully phenocopies Norad deletion, resulting in rapid-onset aging-associated phenotypes. These findings provide new insights and open new lines of investigation into the roles of noncoding RNAs and RNA binding proteins in normal physiology and aging.
Project description:Although numerous long noncoding RNAs (lncRNAs) have been identified, our understanding of their roles in mammalian physiology remains limited. Here we investigated the physiologic function of the conserved lncRNA Norad in vivo. Deletion of Norad in mice results in genomic instability and mitochondrial dysfunction, leading to a dramatic multi-system degenerative phenotype resembling premature aging. Loss of tissue homeostasis in Norad-deficient animals is attributable to augmented activity of PUMILIO proteins, which act as post-transcriptional repressors of target mRNAs to which they bind. Norad is the preferred RNA target of PUMILIO2 (PUM2) in mouse tissues and, upon loss of Norad, PUM2 hyperactively represses key genes required for mitosis and mitochondrial function. Accordingly, enforced Pum2 expression fully phenocopies Norad deletion, resulting in rapid-onset aging-associated phenotypes. These findings provide new insights and open new lines of investigation into the roles of noncoding RNAs and RNA binding proteins in normal physiology and aging.
Project description:Metabolic dysfunction is a primary feature of Werner syndrome (WS), a human premature aging disease caused by mutations in the gene encoding the Werner (WRN) DNA helicase. WS patients exhibit severe metabolic phenotypes, but the underlying mechanisms are not understood, and whether the metabolic deficit can be targeted for therapeutic intervention has not been determined. Here we report impaired mitophagy and depletion of NAD+, a fundamental ubiquitous molecule, in WS patient samples and WS invertebrate models. WRN regulates transcription of a key NAD+ biosynthetic enzyme nicotinamide nucleotide adenylyltransferase 1 (NMNAT1). NAD+ repletion restores NAD+ metabolic profiles and improves mitochondrial quality through DCT-1 and ULK-1-dependent mitophagy. At the organismal level, NAD+ repletion remarkably extends lifespan and delays accelerated aging, including stem cell dysfunction, in C. elegans and Drosophila melanogaster models of WS. Our findings suggest that accelerated aging in WRN syndrome is mediated by impaired mitochondrial function and mitophagy, and that bolstering cellular NAD+ levels counteracts WS phenotypes.
Project description:<p>Metabolic dysfunction is a primary feature of Werner syndrome (WS), a human premature aging disease caused by mutations in the gene encoding the Werner (WRN) DNA helicase. WS patients exhibit severe metabolic phenotypes, but the underlying mechanisms are not understood, and whether the metabolic deficit can be targeted for therapeutic intervention has not been determined. Here we report impaired mitophagy and depletion of NAD+, a fundamental ubiquitous molecule, in WS patient samples and WS invertebrate models. WRN regulates transcription of a key NAD+ biosynthetic enzyme nicotinamide nucleotide adenylyltransferase 1 (NMNAT1). NAD+ repletion restores NAD+ metabolic profiles and improves mitochondrial quality through DCT-1 and ULK-1-dependent mitophagy. At the organismal level, NAD+ repletion remarkably extends lifespan and delays accelerated aging, including stem cell dysfunction, in C. elegans and Drosophila melanogaster models of WS. Our findings suggest that accelerated aging in WRN syndrome is mediated by impaired mitochondrial function and mitophagy, and that bolstering cellular NAD+ levels counteracts WS phenotypes.</p><p><br></p><p><strong>Extracellular UPLC-MS assay</strong> protocols and data are reported in the current study <a href=https://www.ebi.ac.uk/metabolights/MTBLS1221 target=_blank><strong>MTBLS1221</strong></a>.</p><p><strong>Intracellular UPLC-MS assay</strong> protocols and data are reported in <a href=https://www.ebi.ac.uk/metabolights/MTBLS1223 target=_blank><strong>MTBLS1223</strong></a>.</p>
Project description:<p>Metabolic dysfunction is a primary feature of Werner syndrome (WS), a human premature aging disease caused by mutations in the gene encoding the Werner (WRN) DNA helicase. WS patients exhibit severe metabolic phenotypes, but the underlying mechanisms are not understood, and whether the metabolic deficit can be targeted for therapeutic intervention has not been determined. Here we report impaired mitophagy and depletion of NAD+, a fundamental ubiquitous molecule, in WS patient samples and WS invertebrate models. WRN regulates transcription of a key NAD+ biosynthetic enzyme nicotinamide nucleotide adenylyltransferase 1 (NMNAT1). NAD+ repletion restores NAD+ metabolic profiles and improves mitochondrial quality through DCT-1 and ULK-1-dependent mitophagy. At the organismal level, NAD+ repletion remarkably extends lifespan and delays accelerated aging, including stem cell dysfunction, in C. elegans and Drosophila melanogaster models of WS. Our findings suggest that accelerated aging in WRN syndrome is mediated by impaired mitochondrial function and mitophagy, and that bolstering cellular NAD+ levels counteracts WS phenotypes.</p><p><br></p><p><strong>Intracellular UPLC-MS</strong> assay protocols and data are reported in the current study <a href=https://www.ebi.ac.uk/metabolights/MTBLS1223 target=_blank><strong>MTBLS1223</strong></a>.</p><p><strong>Extracellular UPLC-MS</strong> assay protocols and data are reported in <a href=https://www.ebi.ac.uk/metabolights/MTBLS1221 target=_blank><strong>MTBLS1221</strong></a>.</p>