| 1. |
- Caballero, Antonio, et al.
(författare)
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Absence of mitochondrial translation control proteins extends life span by activating sirtuin-dependent silencing.
- 2011
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Ingår i: Molecular cell. - : Elsevier BV. - 1097-4164 .- 1097-2765. ; 42:3, s. 390-400
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Tidskriftsartikel (refereegranskat)abstract
- Altered mitochondrial functionality can extend organism life span, but the underlying mechanisms are obscure. Here we report that inactivating SOV1, a member of the yeast mitochondrial translation control (MTC) module, causes a robust Sir2-dependent extension of replicative life span in the absence of respiration and without affecting oxidative damage. We found that SOV1 interacts genetically with the cAMP-PKA pathway and the chromatin remodeling apparatus. Consistently, Sov1p-deficient cells displayed reduced cAMP-PKA signaling and an elevated, Sir2p-dependent, genomic silencing. Both increased silencing and life span extension in sov1Δ cells require the PKA/Msn2/4p target Pnc1p, which scavenges nicotinamide, a Sir2p inhibitor. Inactivating other members of the MTC module also resulted in Sir2p-dependent life span extension. The data demonstrate that the nuclear silencing apparatus senses and responds to the absence of MTC proteins and that this response converges with a pathway for life span extension elicited by reducing TOR signaling.
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| 2. |
- Öling, David, et al.
(författare)
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Loss of Ubp3 increases Silencing, decreases Unequal Recombination in rDNA, and shortens the Replicative Life Span in Saccharomyces cerevisiae.
- 2014
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Ingår i: Molecular Biology of the Cell. - 1059-1524. ; 25:12, s. 1916-1924
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Tidskriftsartikel (refereegranskat)abstract
- Ubp3 is a conserved ubiquitin protease that acts as an antisilencing factor in MAT and telomeric regions. Here we show that ubp3∆ mutants also display increased silencing in ribosomal DNA (rDNA). Consistent with this, RNA polymerase II occupancy is lower in cells lacking Ubp3 than in wild-type cells in all heterochromatic regions. Moreover, in a ubp3∆ mutant, unequal recombination in rDNA is highly suppressed. We present genetic evidence that this effect on rDNA recombination, but not silencing, is entirely dependent on the silencing factor Sir2. Further, ubp3∆ sir2∆ mutants age prematurely at the same rate as sir2∆ mutants. Thus our data suggest that recombination negatively influences replicative life span more so than silencing. However, in ubp3∆ mutants, recombination is not a prerequisite for aging, since cells lacking Ubp3 have a shorter life span than isogenic wild-type cells. We discuss the data in view of different models on how silencing and unequal recombination affect replicative life span and the role of Ubp3 in these processes.
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| 3. |
- Öling, David, et al.
(författare)
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Opposing roles of Ubp3-dependent deubiquitination regulate replicative life span and heat resistance
- 2014
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Ingår i: Embo Journal. - : Wiley. - 0261-4189 .- 1460-2075. ; 33:7, s. 747-761
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Tidskriftsartikel (refereegranskat)abstract
- Abstract The interplay between molecular chaperones, ubiquitin/deubiquitinating enzymes, and proteasomes is a critical element in protein homeostasis. Among these factors, the conserved deubiquitinase, Ubp3, has the interesting ability, when overproduced, to suppress the requirement for the major cytosolic Hsp70 chaperones. Here, we show that Ubp3 overproduction counteracts deficiency of Hsp70s by the removal of damaged proteins deposited in inclusion bodies (JUNQ) during both aging and heat stress. Consistent with this, Ubp3 destabilized, deubiquitinated, and diminished the toxicity of the JUNQ-associated misfolded protein Ubc9(ts) in a proteasome-dependent manner. In contrast, another misfolded model protein, increment ssCPY*, was stabilized by Ubp3-dependent deubiquitination demonstrating a dual role for Ubp3, saving or destroying aberrant protein species depending on the stage at which the damaged protein is committed for destruction. We present genetic evidence for the former of these activities being key to Ubp3-dependent suppression of heat sensitivity in Hsp70-deficient cells, whereas protein destruction suppresses accelerated aging. We discuss the data in view of how heat stress and aging might elicit differential damage and challenges on the protein homeostasis network. The conserved deubiquitinase Ubp3 regulates both heat stress resistance and replicative life span in yeast through dual roles in cellular protein homeostasis. Ubp3 aids removal of damaged proteins either by stabilizing them in a rescue pathway or by accelerating their proteasome-mediated degradation. Ubp3 promotes the removal of damaged proteins deposited in JUNQ inclusion bodies. Misfolded model proteins are either stabilized or degraded by Ubp3 overproduction. Ubp3 suppresses heat sensitivity in Hsp70-deficient cells by diverting damaged proteins from destruction. Ubp3-mediated proteasomal degradation of cytotoxic proteins suppresses accelerated replicative aging.
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