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- 1. 1 Ursula Heins Marroquín Journal Club 22.03.17
- 2. 2 Saccharomyces cerevisiae (Budding yeast) unicellular eukaryotic organism small genome comprising about 6000 genes, which has been completely sequenced molecular genetic tools Cost effective model Easy to manipulate High throughput screening 31% of yeast gene has a human homolog
- 3. 3 Introduction S. cerevisiae Aged yeast cells - Mitochondria fragmentation - Increase ROS - Loss of mitochondrial DNA AGEING Chronological life span Replicative life span S. cerevisiae
- 4. 4 Introduction S. cerevisiae Aged yeast cells - Mitochondria fragmentation - Increase ROS - Loss of mitochondrial DNA AGEING Chronological life span Replicative life span S. cerevisiae Number of times an individual cell divides
- 6. 6 Method: Mother enrichment program (MEP) Mother Cell Cell division Daughter Cell
- 7. 7 Method: Mother enrichment program (MEP) Daughter Cell the transcription factor Ace2 Sequester in the cytoplasm Transported into the nucleus
- 8. 8 Method: Mother enrichment program (MEP) Cre- EBD78 SUMO-conjugating enzyme Activator of the anaphase-promoting complex (APC) Arrest in M-phase
- 9. 9 Results: Mitochondrial dysfunction in aged yeast Calcofluor staining of the bud scar TOM70-GFP Mitochondrial marker Nr. Cell division Characterization of age-associated mitochondrial phenotypes
- 10. 10 Results: Decreased of mitochondrial function DiOC6 : ΔΨ-dependent mitochondrial fluorescent dye
- 11. 11 Mitochondrial structure in young cells 250 genes1) 2) Overexpression of the 250 genes MEP strain expressing Tom70-GFP Delayed to the onset of altered mitochondrial morphology in aged cells
- 12. 12 Results: VAM1 and VPH2 VAM1 VPH2 A Catalytic subunit of V-ATPase V-ATPase assembly V-ATPase : Acidification of the vacuole Overexpression of VMA suppressed mitochondrial dysfunction in 93 % Overexpression of VPH2 suppressed mitochondrial dysfunction in 77 % Suppression by VMA1 or VPH2 overexpression required V-ATPase activity
- 13. 13 Results: Vacuolar and mitochondrial function are linked • Overexpression of VMA1 and VPH2 increase both media and maximal replicative lifespan.
- 14. 14 How vpH affects mitochondrial function? vacuolar protein degradation? Deletion of PEP4 No alteration of mitochondrial structure
- 15. 15 How vpH affects mitochondrial function? Import of vacuolar metabolite? Overexpression of vacuolar importers + ConcA ATV1 Neutral amino acid transporter Prevent mitochondrial dysfunction
- 16. 16 Results: ATV1 prevents mitochondrial fragmentation Overexpression of ATV1 • Prevent alteration of mitochondrial structure • No change in vacuolar acidification
- 17. 17 Results: ATV1 as aging modulator Deletion of ATV1 Development of age-induced mitochondrial dysfunction Overexpression = Extending RLS Deletion = Shortening of RLS
- 18. 18 Conclusion o Yeast is a good model for aging o Link between vacuolar pH and mitochondrial function o Link between metabolite transport and aging o Vacuole functionalion as aging modulator o Reestablishment of acidification in the vacuole in the daughter cells
- 19. 19 Thank you
Hinweis der Redaktion
- Expression of the Cre recombinase is restricted by a daughter-specific promoter derived from SCW11 (PSCW11) (Figure 1A). Daughter-specific expression from PSCW11 is regulated by the transcription factor Ace2, which is asymmetrically distributed to daughter cell nuclei prior to cytokinesis Cre activity is also post-transcriptionally regulated by fusion to the estradiol-binding domain (EBD) of the murine estrogen receptor (Cre-EBD78). The EBD sequesters the fusion protein in the cytoplasm until estradiol is introduced, at which point the fusion protein is transported into the nucleus where Cre can act upon its loxP DNA substrates
- Mitochondria—which are normally tubular—fragmented and ultimately aggregated in aged cells (Fig. 1a). Mitochondrial fragmentation was present early in the ageing process (86% of cells at 8 divisions), and progressed to large aggregates and small fragments (93% of cells at 17 divisions) that persisted throughout ageing (median lifespan of 28 divisions).
- Mitochondrial membrane potential decreases in aged cells as indicated by DiOC6 staining of aged cells expressing the mitochondrial outer membrane protein Tom70- mCherry. c, Mitochondrial import is reduced in aged cells. Localization of mitochondrial matrix marker preCox4-mCherry in aged cells that also express Tom70-GFP. pre-Cox4-mCherry is localized to the cytoplasm in cells with reduced mitochondrial import. dependent on the membrane potential for protein import, which is imported into mitochondria proportional to the MMP
- Mitochondrial structure is regulated by 250 identified genes in young cells
- Vma1 is the catalytic subunit of the peripheral-membrane-associated V1 sector of the V-ATPase14. Vph2 is an endoplasmic-reticulum-localized integral membrane protein required for V-ATPase assembly15. Overexpression of VMA1 or VPH2 from a high-copy promoter suppressed age-induced mitochondrial dysfunction in 93% and 77% of aged cells, respectively (17 or 16 divisions) (Fig. 1b and Supplementary Fig. 3a). Importantly, suppression by VMA1 or VPH2 overexpression required V-ATPase activity, as treatment with the specific V-ATPase inhibitor concanamycin A (concA)16 blocked their ability to produce normal, tubular mitochondria (Fig. 1b and Supplementary Fig. 3a).
- that resembled mitochondrial phenotypes present in aged cells.
- If reduced import of a particular amino acid or ion into the vacuole led to mitochondrial dysfunction, then overexpressing the transporter required for import of that metabolite into the vacuole might suppress mitochondrial dysfunction in cells with a low vacuolar proton gradient. To test this, we reduced the vacuolar proton gradient by treating cells with low concentrations of concA, and measured mitochondrial DYwith DiOC6 in cells overexpressing individual vacuolar amino acid or ion transporters. Overexpressing most characterized V-ATPasedependent vacuolar importers22–24 had no (NHX1, VBA1, VBA3) or little (VCX1, VBA2) effect on mitochondrial function. However, overexpressing AVT1, a neutral amino acid transporter25, prevented mitochondrial dysfunction in 60% of cells
- If reduced import of a particular amino acid or ion into the vacuole led to mitochondrial dysfunction, then overexpressing the transporter required for import of that metabolite into the vacuole might suppress mitochondrial dysfunction in cells with a low vacuolar proton gradient. To test this, we reduced the vacuolar proton gradient by treating cells with low concentrations of concA, and measured mitochondrial DYwith DiOC6 in cells overexpressing individual vacuolar amino acid or ion transporters. Overexpressing most characterized V-ATPasedependent vacuolar importers22–24 had no (NHX1, VBA1, VBA3) or little (VCX1, VBA2) effect on mitochondrial function. However, overexpressing AVT1, a neutral amino acid transporter25, prevented mitochondrial dysfunction in 60% of cells