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Development and Longevity

Development and Longevity. Weiqing Li. Department of Biological Structure. University of Washington, Seattle. Conj 542, 2/1/11. Developmental Biology. Mechanisms of Aging. Stem Cell Research. Development. Adulthood. ?. 1. Shared signaling cascades? 2. Antagonistic pleiotropy?

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Development and Longevity

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  1. Development and Longevity Weiqing Li Department of Biological Structure University of Washington, Seattle Conj 542, 2/1/11

  2. Developmental Biology Mechanisms of Aging Stem Cell Research

  3. Development Adulthood ? 1. Shared signaling cascades? 2. Antagonistic pleiotropy? 3. More intrinsic connections?

  4. Dwarf mice live longer (4 years and 12 days old — roughly the equivalent of a 136-year-old human) R. Miller, Michigan

  5. Tatar & Antebi, 2003

  6. Each C. elegans can produce about 500 progeny http://www.wormatlas.org/handbook/anatomyintro/anatomyintro.htm

  7. C. elegans as a genetic model organism • short lifespan (15-25 days) • short generation time (<3 days) • genetics: - genetic screen and mutant mapping - gene knockdown by feeding RNAi - gene knockout consortiums • simple transgenic techniques (takes < 3 days to generate • a transgenic line) • strains can be kept at -80°C • transparent • invariant linage

  8. C. elegans organs / tissues Kidney: excretory canals Lung: pseudocoelom Blood: fluid in pseudocoelom Heart: pharynx, body-wall muscle Liver: intestine Skeleton and bone: cuticle Adipose tissue: intestine, pseudocoelom “Immune system”: intestine Macrophages: coelomocytes Pancreas: sensory neurons, intestine Steroidogenic glands: XXX neurons, skin, intestine, somatic gonad

  9. Adverse environmental cues, or down-regulation of insulin signaling, induce dauer arrest in C. elegans normal environment L3 embryo L1 L2 L3 L4 adult dauer • growth arrest • increased fat • extended lifespan adverse environment dauer Insulin receptor mutant

  10. The down-regulation of the insulin pathway results in extended lifespan in C. elegans Insulin receptor PI3 kinase longevity hormone

  11. Khan et al., Science 299: 572, 2003 Mice live longer when insulin receptor function is depleted in the fat tissue FIRKO mice Wild-type mice

  12. Sch9 : an akt homolog Longo, 2009

  13. A conserved insulin signaling pathway in C. elegans insulin-like ligands: DAF-28 and INS1-37 PI’s insulin receptor-like P55 AAP-1 PI3K PTEN lipid phosphatase PI3P’s IST-1 IRS-1 kinases PDK-1 on off FOXO transcription factor development metabolism aging & etc.

  14. Baumeister et al., 2006

  15. Ciliated sensory neurons are exposed to sense the environment ASI ASJ ciliated endings nerve ring ASI ASJ Pdaf-28 (insulin)::GFP http://www.wormatlas.org/handbook/ amphid

  16. Growth vs. Survival delay / limit growth delay reproduction conserve energy turn on stress responses live long grow fast and reproduce adverse environments: protect your body (somatic maintenance) good environments: live normally

  17. The Activation of Five Signaling Pathways is Required to Prevent Dauer Arrest insulin signaling TOR signaling cGMP signaling dauer arrest ? TGF- signaling steroid signaling

  18. pha-4 Baumeister et al., 2006

  19. The diseases of affluence Obesity diatetes, hypertention, heart disease, stroke. Diabetes blindness, kidney failure, heart diseases, stroke, nerve problems, premature death.

  20. Famine Food abundant survivors? diabetic

  21. Development Adulthood ? 1. Shared signaling cascades? 2. Antagonistic pleiotropy? 3. More intrinsic connections?

  22. insulins PI’s P55 PI3P’s IRS-1 development metabolism aging & etc. Genetics revealed the insulin/IGF-1 pathway in C. elegans reverse genetics forward genetics functional genomics (RNAi knockdown) AKT-1 P55 INS-7 INS-18 AKT-1 AKT-2 INS-11 DAF-2 AGE-1 DAF-28 classical genetics deletion knockouts identify gene functions suppressor screens: DAF-18/PTEN DAF-16/FOXO PDK-1 (gf) AKT-1 (gf) mechanisms of biological processes reporter-based screens:

  23. Functional genomics ( RNAi screen) C. elegans chromosome Known/predicted ORFs (~19,000) A B C D E F E. coli expressing individual RNAi clones A B C D E F Add worms Eat bacteria & take up specific dsRNA Score phenotypes Andy Fraser, Ravi Kamath, Julie Ahringer, MRC/Wellcome, UK

  24. Longevity Determined by Developmental Arrest Genes in Caenorhabditis elegans Chen et al., 2007 57 larval arrest genes RNAi during adulthood 24 longevity regulators Mitochondrial genes, Genes affecting translation, transcription

  25. Lifespan Regulation by Evolutionarily Conserved Genes Essential for Viability Curran and Ruvkun, 2007 2,700 essential genes RNAi during adulthood 64 longevity regulators Insulin and metabolic pathways; Translation, RNA and chromatin factors.

  26. pha-4/FoxA skn-1/Nrf1, 2

  27. http://www.wormatlas.org/

  28. Blastomere Identity in C. elegans makes mesoderm (muscle, pharynx) progeny make pharynx and epidermis due to induction from MS makes gut

  29. 1994

  30. daf-16: FoxO, mediates insulin signaling eat-2: nicotinic acetylcholine receptor 2007

  31. Nrf target genes: Phase II detoxification enzymes, including gcs-1 ROS: reactive oxygen species Hyung An and Blackwell, 2008

  32. skn-1-dependent GCS-1::GFP expression in the intestine and ASI neurons Stressor: heat (or paraquat)

  33. Stress-induced nuclear accumulation of SKN-1::GFP

  34. The Activation of Five Signaling Pathways is Required to Prevent Dauer Arrest insulin signaling TOR signaling cGMP signaling dauer arrest ? TGF- signaling steroid signaling

  35. Tatar & Antebi, 2003

  36. Each C. elegans can produce about 500 progeny http://www.wormatlas.org/handbook/anatomyintro/anatomyintro.htm

  37. Xie, 2008

  38. Germline development, notch signaling and stem cell model in C. elegans LAG-2(delta)::GFP GLP-1(notch)::RFP

  39. Depletion of germ-line stem cells extends lifespan Z1 Z4 Z2 Z3 Ablation of Z2, Z3: extended lifespan DTC DTC Ablation of Z1,Z2, Z3, Z4: normal lifespan Ablation of Z2, Z3 In daf-16/FOXO(-): normal lifespan glp-1/notch (-): defective germ-line, extended lifespan Kenyon lab (UCSF)

  40. RNAi screen (LGI) for normal lifespan Identification of kri-1 (ankyrin repeats) glp-1/ notch(-) RNAi of known steroid pathway genes Involvement of steroid signaling glp-1/ notch(-) (lifespan, DAF-16::GFP)

  41. A functional Pkri-1::KRI-1::GFP indicates that kri-1 is expressed in the intestine

  42. kri-1 mediates the longevity signal triggered by loss of germline specifically

  43. RNAi of kri-1 or steroid-pathway genes blocked nuclear DAF-16::GFP loss of germline stem cells daf-9/cyp daf-12/nhr kri-1 daf-16/FOXO

  44. The steroid signal(s) triggered by loss of germline may be generated in both the somatic gonad and intestine daf-36(oxygenase)::gfp Rottiers et al., 2006

  45. Xie, 2008

  46. glp-1 animals store less fat when daf-16 and kri-1 functions are normal Wang et al., 2008

  47. K04A8.5(RNAi) A triglyceride lipase (K04A8.5) regulatesfat storage and longevity in response to loss of GCS signal K04A8.5 Q-PCR (WT vs. glp-1) K04A8.5 RNAi knock-down K04A8.5 overexpression Wang et al., 2008

  48. Inhibition of GCS proliferation triggers the signal

  49. Inhibition of GCS proliferation triggers the signal K04A8.5 Q-PCR

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