Molecular mechanisms of anti-ageing hormetic effects of mild stress….

1. Molecular mechanisms of anti-ageing hormetic effects of mild stress…. Suresh Rattan Editor-in-Chief, BiogerontologyDanish Centre for Molecular Gerontology Department of Molecular Biology University of Aarhus Denmark

2. Approaching ageing/anti-ageing scientifically.... • Describing the phenomenon • Explanation/conceptualisation • Intervention

3. Describing the phenomenon… Species/populations: fungi, insects, worms, fish, bird, mammals Individuals rats, mice, Drosophila, C. elegans, Humans Systems immune, nervous, cardiovascular, endocrine, reproductive, skeletal Organs and tissues brain, heart, liver, lungs, skin, kidney, Cells fibroblasts, keratinocytes, epithelial cells, osteoblasts, T cells, glial cells Organelles nucleus, mitochondria, lysosomes, ER Macromolecules DNA, RNA, proteins, carbohydrates, lipids

4. Understanding ageing1: Functional principle Ageing is the progressive impairment in functional ability, (making us more prone to diseases and death).

5. Genetic principle of ageing There are no real gerontogenes which have evolved to specifically cause ageing.

6. Nature of genes in ageing • Of course, genes can influence lifespan, and several gene mutations have been reported which increase or decrease lifespan through a wide range of molecular pathways. • None of these genes had evolved to specifically cause ageing or terminate life. So, at best, these genes can be termed VIRTUAL GERONTOGENES(Rattan, 1995: FASEB J.)

7. Molecular struggle for survival against constant onslaught... Radiation UV- light Cell Pollution Smoking Oxygen Metabolism Mitochondria

8. Positive correlationswithspecies lifespan • DNA repair • Antioxidant levels • Cell proliferation potential • Cellular responsiveness to stress other correlations which may or may not always hold true are: body mass, brain mass, genome size, ribosome number etc..

9. Biochemical failure of maintenance and repair causes ageing.

10. Strategies to slow down and/orto prevent the failure of maintenance: • Chemical interventions for damage control/removal. • Chemical interventions to stimulate maintenance and repair pathways. • Chemical mimetics of maintenance and repair pathways. • Replenishing lost hormones and other macromolecules, micronutrients. • Nutritional supplements, functional foods.

11. Slowing down ageing from within By making use of the homeodynamic characteristic of living beings.

12. Homeostasis/Homeodynamics Living systems have the ability to counteract and adapt in response to any disturbance, challenge and stress.

13. As a result of homeodynamic ability, a challenge is counteracted, damage repaired, and a new adapted state for survival is achieved.(if not, the system is dead!!).

14. Stress response and longevity... • Cells and organisms selected for resistance to severe stress have enhanced survival and longevity. • Genetically engineered cells and organisms with overexpressing stress response genes have increased longevity.

15. Induction of defence and repair pathways by mild stress has beneficial effects for cells and organisms. Mild stress... This effect is known as HORMESIS.

16. Exercise as a paradigm for hormesis • Biochemically, exercise is damaging. • But, biologically, it is generally good - HORMETICALLY

17. Hormesis could be a way to improve maintenance and repair processes, and to slow down the progression of ageing.

18. Heat shock response in a cell Extracellular stress HSF1 DNA binding Transcription Activation & translocation Inactive HSF1 Translation Intracellular stress Substrate binding Denatured protein HSP Degradation Refolding Functional protein Degradation Proteasome Lysosome

19. Repated mild heat shock and cellular ageing • Mild heat shock at 41° C, twice a week, throughout replicative lifespan of human skin fibroblasts has no negative effects on: Cell survival Cell attachment Growth rates and PD rates Cell yield CPDL

20. Biological effects of repeated mild heat stress on human fibroblasts • Reduced cell enlargement. • Redued irregularization. • Reduced lipofuscin-containing residual bodies. • Reduction in the level of oxidatively- and glycoxidatively-damaged proteins. • Increased resistance to other stresses: UV-A, ethanol, hydrogen-peroxide.

21. Mechanisms of hormesis - 1 • 2 to 3-fold increase in the level of reduced glutathione (GSH). • 2-fold reduction in oxidized glutathione (GSSG). • Increased levels of Hsp27, Hsc70 and Hsp70. • Decreased levels of Hsp90.

22. Mechanisms of hormesis - 2:Improved protein degradation machinery - proteasome Proteasomal activities are stimulated by mild heat stress. Proteasomal content is not affected by mild heat stress.

23. Mechanisms of hormesis - 3:Stimulation of proteasome via its activators The content of the 11S, but not of the 19S, activator is increased. The binding of the 11S activator is enhanced in young cells.

24. Hormetic questions yet to be resolved...... How do cells sense stress and how quickly? What are the molecular differences between mild and severe stress-response? What are the differences in hormetic-response of different cells, organs, tissues, individuals...? Can different stresses be combined, and to what extent? What is the ideal hormetic regime - intensity, frequency?

25. Aging hormetically Brian Clark Anuresh & Suresh Rattan • Technical backbone Gunhild Siboska, Helle Jacobsen, Anne Gylling • Students and post-docs Rasmus Beedholm, Lakshman Sodagam, Regina Gonzalez, Ripudaman Singh, Elise Nielsen, David Kraft and Yvonne Eskildsen-Helmond. Financial support from: Danish Medical and Science Research Councils SSVF & SNF, EU-Biomed Programmes and Senetek PLC,......