RNAi Screening Implicates a SKN-1–Dependent Transcriptional Response in Stress Resistance and Longevity Deriving from Translation Inhibition

Caenorhabditis elegans SKN-1 (ortholog of mammalian Nrf1/2/3) is critical for oxidative stress resistance and promotes longevity under reduced insulin/IGF-1–like signaling (IIS), dietary restriction (DR), and normal conditions. SKN-1 inducibly activates genes involved in detoxification, protein homeostasis, and other functions in response to stress. Here we used genome-scale RNA interference (RNAi) screening to identify mechanisms that prevent inappropriate SKN-1 target gene expression under non-stressed conditions. We identified 41 genes for which knockdown leads to activation of a SKN-1 target gene (gcs-1) through skn-1-dependent or other mechanisms. These genes correspond to multiple cellular processes, including mRNA translation. Inhibition of translation is known to increase longevity and stress resistance and may be important for DR–induced lifespan extension. One model postulates that these effects derive from reduced energy needs, but various observations suggest that specific longevity pathways are involved. Here we show that translation initiation factor RNAi robustly induces SKN-1 target gene transcription and confers skn-1-dependent oxidative stress resistance. The accompanying increases in longevity are mediated largely through the activities of SKN-1 and the transcription factor DAF-16 (FOXO), which is required for longevity that derives from reduced IIS. Our results indicate that the SKN-1 detoxification gene network monitors various metabolic and regulatory processes. Interference with one of these processes, translation initiation, leads to a transcriptional response whereby SKN-1 promotes stress resistance and functions together with DAF-16 to extend lifespan. This stress response may be beneficial for coping with situations that are associated with reduced protein synthesis.

[1]  R. Deshaies,et al.  Transcription factor Nrf1 mediates the proteasome recovery pathway after proteasome inhibition in mammalian cells. , 2010, Molecular cell.

[2]  C. Kenyon.  The genetics of ageing , 2010, Nature.

[3]  G. Sykiotis,et al.  Stress-Activated Cap'n'collar Transcription Factors in Aging and Human Disease , 2010, Science Signaling.

[4]  L. Partridge,et al.  Mechanisms of Life Span Extension by Rapamycin in the Fruit Fly Drosophila melanogaster , 2010, Cell metabolism.

[5]  B. Kennedy,et al.  Hot topics in aging research: protein translation, 2009 , 2009, Aging cell.

[6]  J. Yewdell,et al.  Innate Immune and Chemically Triggered Oxidative Stress Modifies Translational Fidelity , 2009, Nature.

[7]  Seung-Jae V. Lee,et al.  Glucose shortens the life span of C. elegans by downregulating DAF-16/FOXO activity and aquaporin gene expression. , 2009, Cell metabolism.

[8]  T. Blackwell,et al.  Life is short, if sweet. , 2009, Cell metabolism.

[9]  Atsushi Fukushima,et al.  Reactive oxygen species enhance insulin sensitivity. , 2009, Cell metabolism.

[10]  Janet M. Thornton,et al.  Ribosomal Protein S6 Kinase 1 Signaling Regulates Mammalian Life Span , 2009, Science.

[11]  Subhash D. Katewa,et al.  4E-BP Extends Lifespan upon Dietary Restriction by Enhancing Mitochondrial Activity in Drosophila , 2009, Cell.

[12]  C. Murphy,et al.  Condition‐adapted stress and longevity gene regulation by Caenorhabditis elegans SKN‐1/Nrf , 2009, Aging cell.

[13]  T. Johnson,et al.  Oxidative stress and longevity in Caenorhabditis elegans as mediated by SKN‐1 , 2009, Aging cell.

[14]  Daniel A Chamovitz,et al.  Revisiting the COP9 signalosome as a transcriptional regulator , 2009, EMBO reports.

[15]  L. Pintard,et al.  In the land of the rising sun with the COP9 signalosome and related Zomes , 2009, EMBO reports.

[16]  K. Choe,et al.  The WD40 Repeat Protein WDR-23 Functions with the CUL4/DDB1 Ubiquitin Ligase To Regulate Nuclear Abundance and Activity of SKN-1 in Caenorhabditis elegans , 2009, Molecular and Cellular Biology.

[17]  A. Hinnebusch,et al.  Regulation of Translation Initiation in Eukaryotes: Mechanisms and Biological Targets , 2009, Cell.

[18]  B. Morgan,et al.  A redox-sensitive peroxiredoxin that is important for longevity has tissue- and stress-specific roles in stress resistance , 2008, Proceedings of the National Academy of Sciences.

[19]  A. Yamaguchi,et al.  Inhibition of a eukaryotic initiation factor (eIF2Bδ,/F11A3.2) during adulthood extends lifespan in Caenorhabditis elegans , 2008, FASEB journal : official publication of the Federation of American Societies for Experimental Biology.

[20]  S. Mango,et al.  The Target of Rapamycin Pathway Antagonizes pha-4/FoxA to Control Development and Aging , 2008, Current Biology.

[21]  A. Antebi,et al.  C. elegans dauer formation and the molecular basis of plasticity. , 2008, Genes & development.

[22]  William B. Mair,et al.  Aging and survival: the genetics of life span extension by dietary restriction. , 2008, Annual review of biochemistry.

[23]  S. Lenzen.  Oxidative stress: the vulnerable beta-cell. , 2008, Biochemical Society transactions.

[24]  Matt Kaeberlein,et al.  Yeast Life Span Extension by Depletion of 60S Ribosomal Subunits Is Mediated by Gcn4 , 2008, Cell.

[25]  Alfred L. Fisher,et al.  The Caenorhabditis elegans K10C2.4 Gene Encodes a Member of the Fumarylacetoacetate Hydrolase Family , 2008, Journal of Biological Chemistry.

[26]  C. Sevier,et al.  Ero1 and redox homeostasis in the endoplasmic reticulum. , 2008, Biochimica et biophysica acta.

[27]  Jennifer M. A. Tullet,et al.  Direct Inhibition of the Longevity-Promoting Factor SKN-1 by Insulin-like Signaling in C. elegans , 2008, Cell.

[28]  T. Johnson,et al.  Proteasomal dysfunction activates the transcription factor SKN-1 and produces a selective oxidative-stress response in Caenorhabditis elegans. , 2008, The Biochemical journal.

[29]  G. Sykiotis,et al.  Keap1/Nrf2 signaling regulates oxidative stress tolerance and lifespan in Drosophila. , 2008, Developmental cell.

[30]  A. Antebi,et al.  Genetics of Aging in Caenorhabditis elegans , 2007, PLoS genetics.

[31]  P. Kapahi,et al.  Longevity determined by developmental arrest genes in Caenorhabditis elegans , 2007, Aging cell.

[32]  L. Guarente,et al.  Two neurons mediate diet-restriction-induced longevity in C. elegans , 2007, Nature.

[33]  M. Tyers,et al.  CIF-1, a Shared Subunit of the COP9/Signalosome and Eukaryotic Initiation Factor 3 Complexes, Regulates MEL-26 Levels in the Caenorhabditis elegans Embryo , 2007, Molecular and Cellular Biology.

[34]  G. Ruvkun,et al.  Lifespan Regulation by Evolutionarily Conserved Genes Essential for Viability , 2007, PLoS genetics.

[35]  Nektarios Tavernarakis,et al.  eIF4E function in somatic cells modulates ageing in Caenorhabditis elegans , 2007, Nature.

[36]  P. Kapahi,et al.  Inhibition of mRNA translation extends lifespan in Caenorhabditis elegans , 2007, Aging cell.

[37]  Seung-Jae V. Lee,et al.  Lifespan extension by conditions that inhibit translation in Caenorhabditis elegans , 2007, Aging cell.

[38]  Hannah J. Zhang,et al.  An integrated view of oxidative stress in aging: basic mechanisms, functional effects, and pathological considerations. , 2007, American journal of physiology. Regulatory, integrative and comparative physiology.

[39]  T. Johnson,et al.  daf-16 protects the nematode Caenorhabditis elegans during food deprivation. , 2006, The journals of gerontology. Series A, Biological sciences and medical sciences.

[40]  Masayuki Yamamoto,et al.  Nrf2-Keap1 regulation of cellular defense mechanisms against electrophiles and reactive oxygen species. , 2006, Advances in enzyme regulation.

[41]  Kunihiro Matsumoto,et al.  Regulation of the Caenorhabditis elegans oxidative stress defense protein SKN-1 by glycogen synthase kinase-3. , 2005, Proceedings of the National Academy of Sciences of the United States of America.

[42]  E. Nishida,et al.  The C. elegans p38 MAPK pathway regulates nuclear localization of the transcription factor SKN-1 in oxidative stress response. , 2005, Genes & development.

[43]  G. Ruvkun,et al.  A systematic RNAi screen for longevity genes in C. elegans. , 2005, Genes & development.

[44]  Hendrik C Korswagen,et al.  Functional Interaction Between ß-Catenin and FOXO in Oxidative Stress Signaling , 2005, Science.

[45]  J. McElwee,et al.  Broad spectrum detoxification: the major longevity assurance process regulated by insulin/IGF-1 signaling? , 2005, Mechanisms of Ageing and Development.

[46]  A. Kong,et al.  Induction of phase I, II and III drug metabolism/transport by xenobiotics , 2005, Archives of pharmacal research.

[47]  David E Hill,et al.  Toward improving Caenorhabditis elegans phenome mapping with an ORFeome-based RNAi library. , 2004, Genome research.

[48]  S. Benzer,et al.  Regulation of Lifespan in Drosophila by Modulation of Genes in the TOR Signaling Pathway , 2004, Current Biology.

[49]  Tibor Vellai,et al.  Genetics: Influence of TOR kinase on lifespan in C. elegans , 2003, Nature.

[50]  R. Deshaies,et al.  COP9 Signalosome A Multifunctional Regulator of SCF and Other Cullin-Based Ubiquitin Ligases , 2003, Cell.

[51]  T. Blackwell,et al.  SKN-1 links C. elegans mesendodermal specification to a conserved oxidative stress response. , 2003, Genes & development.

[52]  R. Kamath,et al.  Genome-wide RNAi screening in Caenorhabditis elegans. , 2003, Methods.

[53]  G. Lithgow,et al.  Stress resistance as a determinate of C. elegans lifespan , 2002, Mechanisms of Ageing and Development.

[54]  C. Link,et al.  Reporter transgenes for study of oxidant stress in Caenorhabditis elegans. , 2002, Methods in enzymology.

[55]  W. Dröge.  Free radicals in the physiological control of cell function. , 2002, Physiological reviews.

[56]  M. McMahon,et al.  Molecular basis for the contribution of the antioxidant responsive element to cancer chemoprevention. , 2001, Cancer letters.

[57]  M. Brownlee.  Biochemistry and molecular cell biology of diabetic complications , 2001, Nature.

[58]  P. Zipperlen,et al.  Effectiveness of specific RNA-mediated interference through ingested double-stranded RNA in Caenorhabditis elegans , 2000, Genome Biology.

[59]  A. Varshavsky,et al.  Detecting and measuring cotranslational protein degradation in vivo. , 2000, Science.

[60]  Jonathan W. Yewdell,et al.  Rapid degradation of a large fraction of newly synthesized proteins by proteasomes , 2000, Nature.

[61]  Y Honda,et al.  The daf‐2 gene network for longevity regulates oxidative stress resistance and Mn‐superoxide dismutase gene expression in Caenorhabditis elegans , 1999, FASEB journal : official publication of the Federation of American Societies for Experimental Biology.

[62]  G. Ruvkun,et al.  The Fork head transcription factor DAF-16 transduces insulin-like metabolic and longevity signals in C. elegans , 1997, Nature.

[63]  Bruce Bowerman,et al.  skn-1, a maternally expressed gene required to specify the fate of ventral blastomeres in the early C. elegans embryo , 1992, Cell.