Project description:We demonstrate that transcriptomic profiling of the NER mutant ercc-1 offers better understanding of the complex phenotypes of ercc-1 deficiency in C. elegans, as it does in mammalian models. There is a transcriptomic shift in ercc-1 mutants that suggests a stochastic impairment of growth and development, with a shift towards a higher proportion of males in the population. Extensive phenotypic analyses confirm that NER deficiency in C. elegans leads to severe developmental and growth defects and a reduced replicative lifespan, although post-mitotic lifespan is not affected. Results suggest that these defects are caused by an inability to cope with randomly occurring DNA damage, which may interfere with transcription and replication. The study investigates the developmental and aging phenotypes of different NER deficient C. elegans mutants (xpa-1, ercc-1, xpf-1 and xpg-1), where the transcriptomic profile of ercc-1 mutant is presented. We show that loss of NER function does not affect post-mitotic lifespan, but leads to impaired embryogenesis, germ cell and larval development and causes a reduced replicative lifespan. Phenotypes are most pronounced in ercc-1, xpf-1 and xpg-1 mutant animals. We provide evidence that this more pronounced phenotype is likely caused by the fact that these genes are involved in multiple repair pathways besides NER. Furthermore, transcriptional profiling of ercc-1 mutants confirms these observations, showing that growth and developmental pathways are underrepresented but that insulin signaling is not affected. Our analysis suggests that XPA-1, ERCC-1, XPF-1 and XPG-1 protect animals against replicative aging by preventing the accumulation of randomly acquired DNA damage. Eight mixed stage C. elegans samples were run on Affymetrix GeneChip C. elegans Genome Arrays. Four samples belong to ercc-1 mutant group and four to the wild-type, N2.
Project description:We demonstrate that transcriptomic profiling of the NER mutant ercc-1 offers better understanding of the complex phenotypes of ercc-1 deficiency in C. elegans, as it does in mammalian models. There is a transcriptomic shift in ercc-1 mutants that suggests a stochastic impairment of growth and development, with a shift towards a higher proportion of males in the population. Extensive phenotypic analyses confirm that NER deficiency in C. elegans leads to severe developmental and growth defects and a reduced replicative lifespan, although post-mitotic lifespan is not affected. Results suggest that these defects are caused by an inability to cope with randomly occurring DNA damage, which may interfere with transcription and replication. The study investigates the developmental and aging phenotypes of different NER deficient C. elegans mutants (xpa-1, ercc-1, xpf-1 and xpg-1), where the transcriptomic profile of ercc-1 mutant is presented. We show that loss of NER function does not affect post-mitotic lifespan, but leads to impaired embryogenesis, germ cell and larval development and causes a reduced replicative lifespan. Phenotypes are most pronounced in ercc-1, xpf-1 and xpg-1 mutant animals. We provide evidence that this more pronounced phenotype is likely caused by the fact that these genes are involved in multiple repair pathways besides NER. Furthermore, transcriptional profiling of ercc-1 mutants confirms these observations, showing that growth and developmental pathways are underrepresented but that insulin signaling is not affected. Our analysis suggests that XPA-1, ERCC-1, XPF-1 and XPG-1 protect animals against replicative aging by preventing the accumulation of randomly acquired DNA damage.
Project description:Targetted metabolomics in U2OS PRDX1 WT and PRDX1-/- While cellular metabolism impacts the DNA damage response, a systematic understanding of the metabolic requirements that are crucial for DNA damage repair has yet to be achieved. Here, we investigate the metabolic enzymes and processes that are essential when cells are exposed to DNA damage. By integrating functional genomics with chromatin proteomics and metabolomics, we provide a detailed description of the interplay between cellular metabolism and the DNA damage response. Subsequent analysis identified Peroxiredoxin 1, PRDX1, as fundamental for DNA damage repair. During the DNA damage response, PRDX1 translocates to the nucleus where it is required to reduce DNA damage-induced nuclear reactive oxygen species levels. Moreover, PRDX1 controls aspartate availability, which is required for the DNA damage repair-induced upregulation of de novo nucleotide synthesis. Loss of PRDX1 leads to an impairment in the clearance of γΗ2ΑΧ nuclear foci, accumulation of replicative stress and cell proliferation defects, thus revealing a crucial role for PRDX1 as a DNA damage surveillance factor.
Project description:Background: The ability of an organism to repair DNA damage is implicated in carcinogenesis and aging. Interestingly expression profiling of Nucleotide Excision Repair (NER) deficient segmental progeroid mice revealed gene expression changes resembling these observed in aged wild type animals. Our previous transcriptional profiling of NER-deficient C. elegans xpa-1 mutant showed overrepresentation of genes involved in lifespan determination and upregulation of several oxidative stress response genes (Fensgard et al. Aging 2010). However, since an independent study performed by Boyd and coworkers (Boyd et al. Mut Res 2010) showed limited number of changes in xpa-1 mutant. Therefore to independently validate that transcriptome modulation does take place in xpa-1 mutants, we performed another global gene expression profiling based on 5 independent biological replicates allowing more stringent statistical analysis. Results: In agreement with what was observed by Boyd and coworkers (Boyd et al. Mut Res 2010) current transcriptomic analysis detected fewer changes in xpa-1 C. elegans mutant with only a few genes regulated more than 4-fold. Nevertheless, Gene Ontology (GO) enrichment analysis performed on statistically significantly regulated unique protein coding genes revealed overrepresentation of aging gene cluster. Moreover, as before, overexpression of several genes involved in oxidative stress responses was detected. Conclusion: More stringent statistical analysis predictably resulted in a smaller number of regulated genes and thus overrepresented GOs comparing to the earlier paper. However, major conclusions of the previous study can be still regarded as valid, as the most important aging GO is still overrepresented. Background: The ability of an organism to repair DNA damage is implicated in carcinogenesis and aging. Interestingly expression profiling of Nucleotide Excision Repair (NER) deficient segmental progeroid mice revealed gene expression changes resembling these observed in aged wild type animals. Our previous transcriptional profiling of NER-deficient C. elegans xpa-1 mutant showed overrepresentation of genes involved in lifespan determination and upregulation of several oxidative stress response genes (Fensgard et al. Aging 2010). However, since an independent study performed by Boyd and coworkers (Boyd et al. Mut Res 2010) showed limited number of changes in xpa-1 mutant. Therefore to independently validate that transcriptome modulation does take place in xpa-1 mutants, we performed another global gene expression profiling based on 5 independent biological replicates allowing more stringent statistical analysis. Results: In agreement with what was observed by Boyd and coworkers (Boyd et al. Mut Res 2010) current transcriptomic analysis detected fewer changes in xpa-1 C. elegans mutant with only a few genes regulated more than 4-fold. Nevertheless, Gene Ontology (GO) enrichment analysis performed on statistically significantly regulated unique protein coding genes revealed overrepresentation of aging gene cluster. Moreover, as before, overexpression of several genes involved in oxidative stress responses was detected. Conclusion: More stringent statistical analysis predictably resulted in a smaller number of regulated genes and thus overrepresented GOs comparing to the earlier paper. However, major conclusions of the previous study can be still regarded as valid, as the most important aging GO is still overrepresented. Background: The ability of an organism to repair DNA damage is implicated in carcinogenesis and aging. Interestingly expression profiling of Nucleotide Excision Repair (NER) deficient segmental progeroid mice revealed gene expression changes resembling these observed in aged wild type animals. Our previous transcriptional profiling of NER-deficient C. elegans xpa-1 mutant showed overrepresentation of genes involved in lifespan determination and upregulation of several oxidative stress response genes (Fensgard et al. Aging 2010). However, since an independent study performed by Boyd and coworkers (Boyd et al. Mut Res 2010) showed limited number of changes in xpa-1 mutant. Therefore to independently validate that transcriptome modulation does take place in xpa-1 mutants, we performed another global gene expression profiling based on 5 independent biological replicates allowing more stringent statistical analysis. Results: In agreement with what was observed by Boyd and coworkers (Boyd et al. Mut Res 2010) current transcriptomic analysis detected fewer changes in xpa-1 C. elegans mutant with only a few genes regulated more than 4-fold. Nevertheless, Gene Ontology (GO) enrichment analysis performed on statistically significantly regulated unique protein coding genes revealed overrepresentation of aging gene cluster. Moreover, as before, overexpression of several genes involved in oxidative stress responses was detected. Conclusion: More stringent statistical analysis predictably resulted in a smaller number of regulated genes and thus overrepresented GOs comparing to the earlier paper. However, major conclusions of the previous study can be still regarded as valid, as the most important aging GO is still overrepresented. Activation of oxidative stress-responses and downregulation of insulin-like signaling (ILS) is seen in Nucleotide Excision Repair (NER) deficient segmental progeroid mice. Evidence suggests that this is a survival response to persistent transcription-blocking DNA damage, although the relevant lesions have not been identified. Here we provide evidence for transcriptional reprogramming in NER-deficient C. elegans xpa-1 by transcriptomic and proteomic approaches. This reprograming is accompanied by increased intracellular ROS and ATP levels and lifespan shortening in xpa-1 mutant. Moreover we show that Base Excision Repair DNA glycosylase NTH-1 is upstream form the signaling events leading to transcriptomic changes, as its downregulation reverses overexpression of sod-3, gst-4 and aqp-1 genes, reduces intracellular ROS and ATP levels and reverses lifespan shortening observed in xpa-1 mutant. Surprisingly, however, these responses appear to not depend on cyclopurine levels, since these lesions are lower in xpa-1 C. elegans mutant than in the wild type. Finally, we also explore here which other upstream factors are necessary for transcriptional reprograming in xpa-1 mutant. Untreated Caenorhabditis elegans mutant deficient in xpa-1 and the wild type N2 strain were subjected to transcriptome analysis using Affymetrix platform. For each sample group five replicates were analyzed.
Project description:Protein synthesis is strictly regulated during replicative aging in yeast, but global translational regulation during replicative aging is poorly characterized. To conduct ribosomal profiling during replicative aging, we collected a large number of dividing aged cells using a miniature chemostat aging device. Translational efficiency, defined as the number of ribosome footprints normalized to transcript abundance, was compared between young and aged cells for each gene. We identified more than 700 genes with changes greater than twofold during replicative aging. Increased translational efficiency was observed in genes involved in DNA repair and chromosome organization. Decreased translational efficiency was observed in genes encoding ribosome components, transposon Ty1 and Ty2 genes, transcription factor HAC1 genes associated with the unfolded protein response, genes involved in cell wall synthesis and assembly, and ammonium permease genes. Our results provide a global view of translational regulation during replicative aging, in which the pathways involved in various cell functions are translationally regulated and cause diverse phenotypic changes.
Project description:Unlike aging somatic cells, which exhibit a decline in molecular fidelity and eventually reach a state of replicative senescence, pluripotent stem cells can indefinitely replenish themselves while retaining full homeostatic capacity. The conferment of beneficial -pluripotency related traits via in vivo partial cellular reprogramming (IVPR) significantly extends lifespan and restores aging phenotypes in mouse models. Although the phases of cellular reprogramming are well characterized, details of the rejuvenation processes are poorly defined. Here we created the first reprogrammable accelerated aging mouse model with a DNA damage repair defect to better understand the effects of reprogramming on a key driver of aging. Using enhanced partial reprogramming by combining small molecules with the Yamanaka factors, we observed potent reversion of DNA damage, significant upregulation of multiple DNA damage repair processes, and restoration of the epigenetic clock is observed. In addition, we present evidence that TGFb inhibition of the ALK5 or ALK2 receptor is able to phenocopy some benefits including epigenetic clock restoration suggesting a role in the mechanism of rejuvenation during partial reprogramming.
Project description:DNA damage comprises a causal factor for aging and aging-associated diseases. Defects in genome maintenance pathways give rise to a variety of human congenital syndromes that are characterized by growth retardation, cancer susceptibility, and accelerated aging. The specific consequences of unrepaired DNA damage in human diseases are particularly apparent in syndromes caused by distinct nucleotide excision repair (NER) defects, however, with yet poorly understood genotype-phenotype correlations and highly complex disease phenotypes. We have established that the equivalent mutations in the simple metazoan Caenorhabditis elegans reflect the distinct outcomes of DNA repair defects and allow investigating the consequences of persistent DNA damage during animal development and aging. Here, we employed proteome, lipidome, and phosphoproteome analysis of NER-deficient animals in response to UV treatment in order to gain comprehensive insights into the full range of physiological adaptations to the presence of unrepaired DNA damage. We derive metabolic changes indicative of a tissue maintenance program and implicate an autophagy-mediated protoestatic response. We assign central roles for the IIS regulator DAF-2 and the EGF-signalling pathway in orchestrating this adaptive response to DNA damage. Our results provide new insights into the DNA damage responses in the organismal context.
Project description:In the yeast Saccharomyces cerevisiae, cleavage factor I (CFI) and cleavage and polyadenylation factor (CPF) build the core of the transcription termination machinery. CFI comprises the Rna14, Rna15, Pcf11, and Clp1 proteins, as well as the associated Hrp5 RNA-binding protein. We found that CFI participates in the DNA damage response and that rna14-1 shows synthetic growth defects with mutants of different repair pathways, including homologous recombination, non-homologous end joining, post replicative repair, mismatch repair, and nucleotide excision repair, implicating that impaired RNAPII termination and 3â-end processing decreases the cellular tolerance for DNA damage. Beyond replication progression defects, we found that bypass of the G1/S checkpoint in rna14-1 cells leads to synthetic sickness, accumulation of phosphorylated H2A, as well as increase in Rad52-foci and in recombination. Our data provide evidence that CFI dysfunction impairs RNAPII turnover, leading to replication hindrance and lower tolerance to exogenous DNA damage. These findings underscore the importance of coordination between transcription termination, DNA repair and replication in the maintenance of genomic stability. S. cerevisiae strains were grown in YPAD liquid culture at 30°C, total RNA was isolated and hybridized on Affymetrix microarrays.
Project description:While cellular metabolism impacts the DNA damage response, a systematic understanding of the metabolic requirements that are crucial for DNA damage repair has yet to be achieved. Here, we investigate the metabolic enzymes and processes that are essential when cells are exposed to DNA damage. By integrating functional genomics with chromatin proteomics and metabolomics, we provide a detailed description of the interplay between cellular metabolism and the DNA damage response. Subsequent analysis identified Peroxiredoxin 1, PRDX1, as fundamental for DNA damage repair. During the DNA damage response, PRDX1 translocates to the nucleus where it is required to reduce DNA damage-induced nuclear reactive oxygen species levels. Moreover, PRDX1 controls aspartate availability, which is required for the DNA damage repair-induced upregulation of de novo nucleotide synthesis. Loss of PRDX1 leads to an impairment in the clearance of γΗ2ΑΧ nuclear foci, accumulation of replicative stress and cell proliferation defects, thus revealing a crucial role for PRDX1 as a DNA damage surveillance factor.