101
|
Hughes AL, Hughes CE, Henderson KA, Yazvenko N, Gottschling DE. Selective sorting and destruction of mitochondrial membrane proteins in aged yeast. eLife 2016; 5. [PMID: 27097106 PMCID: PMC4889329 DOI: 10.7554/elife.13943] [Citation(s) in RCA: 91] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2015] [Accepted: 04/18/2016] [Indexed: 12/31/2022] Open
Abstract
Mitochondrial dysfunction is a hallmark of aging, and underlies the development of many diseases. Cells maintain mitochondrial homeostasis through a number of pathways that remodel the mitochondrial proteome or alter mitochondrial content during times of stress or metabolic adaptation. Here, using yeast as a model system, we identify a new mitochondrial degradation system that remodels the mitochondrial proteome of aged cells. Unlike many common mitochondrial degradation pathways, this system selectively removes a subset of membrane proteins from the mitochondrial inner and outer membranes, while leaving the remainder of the organelle intact. Selective removal of preexisting proteins is achieved by sorting into a mitochondrial-derived compartment, or MDC, followed by release through mitochondrial fission and elimination by autophagy. Formation of MDCs requires the import receptors Tom70/71, and failure to form these structures exacerbates preexisting mitochondrial dysfunction, suggesting that the MDC pathway provides protection to mitochondria in times of stress.
Collapse
Affiliation(s)
- Adam L Hughes
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, United States.,Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, United States
| | - Casey E Hughes
- Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, United States
| | - Kiersten A Henderson
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, United States
| | - Nina Yazvenko
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, United States
| | - Daniel E Gottschling
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, United States
| |
Collapse
|
102
|
A role for Mfb1p in region-specific anchorage of high-functioning mitochondria and lifespan in Saccharomyces cerevisiae. Nat Commun 2016; 7:10595. [PMID: 26839174 PMCID: PMC4742906 DOI: 10.1038/ncomms10595] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2015] [Accepted: 01/04/2016] [Indexed: 01/20/2023] Open
Abstract
Previous studies indicate that replicative lifespan in daughter cells of Sacchraromyces cerevisiae depends on the preferential inheritance of young, high-functioning mitochondria. We report here that mitochondria are functionally segregated even within single mother cells in S. cerevisiae. A high-functioning population of mitochondria accumulates at the tip of the mother cell distal to the bud. We find that the mitochondrial F-box protein (Mfb1p) localizes to mitochondria in the mother tip and is required for mitochondrial anchorage at that site, independent of the previously identified anchorage protein Num1p. Deletion of MFB1 results in loss of the mother-tip-localized mitochondrial population, defects in mitochondrial function and premature replicative ageing. Inhibiting mitochondrial inheritance to buds, by deletion of MMR1, in mfb1Δ cells restores mitochondrial distribution, promotes mitochondrial function and extends replicative lifespan. Our results identify a mechanism that retains a reservoir of high-functioning mitochondria in mother cells and thereby preserves maternal reproductive capacity. Mitochondria are asymmetrically inherited during cell division, a process that can affect cell fate and lifespan. Here the authors describe a mechanism for mitochondrial quality control in yeast that maintains a reservoir of high-functioning mitochondria in mother cells and preserves maternal reproductive capacity.
Collapse
|
103
|
Higuchi-Sanabria R, Vevea JD, Charalel JK, Sapar ML, Pon LA. The transcriptional repressor Sum1p counteracts Sir2p in regulation of the actin cytoskeleton, mitochondrial quality control and replicative lifespan in Saccharomyces cerevisiae. MICROBIAL CELL (GRAZ, AUSTRIA) 2016; 3:79-88. [PMID: 28357337 PMCID: PMC5349106 DOI: 10.15698/mic2016.02.478] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/09/2015] [Accepted: 12/15/2015] [Indexed: 11/13/2022]
Abstract
Increasing the stability or dynamics of the actin cytoskeleton can extend lifespan in C. elegans and S. cerevisiae. Actin cables of budding yeast, bundles of actin filaments that mediate cargo transport, affect lifespan control through effects on mitochondrial quality control. Sir2p, the founding member of the Sirtuin family of lifespan regulators, also affects actin cable dynamics, assembly, and function in mitochondrial quality control. Here, we obtained evidence for novel interactions between Sir2p and Sum1p, a transcriptional repressor that was originally identified through mutations that genetically suppress sir2∆ phenotypes unrelated to lifespan. We find that deletion of SUM1 in wild-type cells results in increased mitochondrial function and actin cable abundance. Furthermore, deletion of SUM1 suppresses defects in actin cables and mitochondria of sir2∆ yeast, and extends the replicative lifespan and cellular health span of sir2∆ cells. Thus, Sum1p suppresses Sir2p function in control of specific aging determinants and lifespan in budding yeast.
Collapse
Affiliation(s)
- Ryo Higuchi-Sanabria
- Department of Pathology and Cell Biology, Columbia University, New
York, NY, USA
| | - Jason D. Vevea
- Department of Pathology and Cell Biology, Columbia University, New
York, NY, USA
- Current address: Department of Neuroscience, University of
Wisconsin, Madison, WI, USA
| | - Joseph K. Charalel
- Department of Pathology and Cell Biology, Columbia University, New
York, NY, USA
- Current address: Department of Genetics, Stanford University,
Stanford, CA, USA
| | - Maria L. Sapar
- Department of Biological Sciences, Hunter College and The Graduate
Center Biochemistry, Biology and Biopsychology and Behavioral Neuroscience Programs,
CUNY, New York, NY 10065, USA. Current address: Weill Institute for Cell and
Molecular Biology, Cornell University, Ithaca, NY, USA
| | - Liza A. Pon
- Department of Pathology and Cell Biology, Columbia University, New
York, NY, USA
- Herbert Irving Comprehensive Cancer Center, Columbia University, New
York, NY, USA
| |
Collapse
|
104
|
Higuchi-Sanabria R, Charalel JK, Viana MP, Garcia EJ, Sing CN, Koenigsberg A, Swayne TC, Vevea JD, Boldogh IR, Rafelski SM, Pon LA. Mitochondrial anchorage and fusion contribute to mitochondrial inheritance and quality control in the budding yeast Saccharomyces cerevisiae. Mol Biol Cell 2016; 27:776-87. [PMID: 26764088 PMCID: PMC4803304 DOI: 10.1091/mbc.e15-07-0455] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2015] [Accepted: 01/07/2016] [Indexed: 11/30/2022] Open
Abstract
Fzo1p contributes to mitochondrial inheritance by fusion of mitochondria that enter the bud to mitochondria that are anchored in the bud tip. This promotes retention of mitochondria in the bud tip. However, it also promotes anchorage of lower-functioning mitochondria in the bud tip, which inhibits clearance of those organelles from buds. Higher-functioning mitochondria that are more reduced and have less ROS are anchored in the yeast bud tip by the Dsl1-family protein Mmr1p. Here we report a role for mitochondrial fusion in bud-tip anchorage of mitochondria. Fluorescence loss in photobleaching (FLIP) and network analysis experiments revealed that mitochondria in large buds are a continuous reticulum that is physically distinct from mitochondria in mother cells. FLIP studies also showed that mitochondria that enter the bud can fuse with mitochondria that are anchored in the bud tip. In addition, loss of fusion and mitochondrial DNA (mtDNA) by deletion of mitochondrial outer or inner membrane fusion proteins (Fzo1p or Mgm1p) leads to decreased accumulation of mitochondria at the bud tip and inheritance of fitter mitochondria by buds compared with cells with no mtDNA. Conversely, increasing the accumulation and anchorage of mitochondria in the bud tip by overexpression of MMR1 results in inheritance of less-fit mitochondria by buds and decreased replicative lifespan and healthspan. Thus quantity and quality of mitochondrial inheritance are ensured by two opposing processes: bud-tip anchorage by mitochondrial fusion and Mmr1p, which favors bulk inheritance; and quality control mechanisms that promote segregation of fitter mitochondria to the bud.
Collapse
Affiliation(s)
- Ryo Higuchi-Sanabria
- Department of Pathology and Cell Biology, Columbia University, New York, NY 10032
| | - Joseph K Charalel
- Department of Pathology and Cell Biology, Columbia University, New York, NY 10032
| | - Matheus P Viana
- Department of Developmental and Cell Biology and Center for Complex Biological Systems, University of California, Irvine, Irvine, CA 92697
| | - Enrique J Garcia
- Department of Pathology and Cell Biology, Columbia University, New York, NY 10032
| | - Cierra N Sing
- Department of Pathology and Cell Biology, Columbia University, New York, NY 10032
| | - Andrea Koenigsberg
- Department of Pathology and Cell Biology, Columbia University, New York, NY 10032
| | - Theresa C Swayne
- Herbert Irving Comprehensive Cancer Center, Columbia University, New York, NY 10032
| | - Jason D Vevea
- Department of Pathology and Cell Biology, Columbia University, New York, NY 10032
| | - Istvan R Boldogh
- Department of Pathology and Cell Biology, Columbia University, New York, NY 10032
| | - Susanne M Rafelski
- Department of Developmental and Cell Biology and Center for Complex Biological Systems, University of California, Irvine, Irvine, CA 92697
| | - Liza A Pon
- Department of Pathology and Cell Biology, Columbia University, New York, NY 10032 Herbert Irving Comprehensive Cancer Center, Columbia University, New York, NY 10032
| |
Collapse
|
105
|
Higuchi-Sanabria R, Swayne TC, Boldogh IR, Pon LA. Live-Cell Imaging of Mitochondria and the Actin Cytoskeleton in Budding Yeast. Methods Mol Biol 2016; 1365:25-62. [PMID: 26498778 DOI: 10.1007/978-1-4939-3124-8_2] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Maintenance and regulation of proper mitochondrial dynamics and functions are necessary for cellular homeostasis. Numerous diseases, including neurodegeneration and muscle myopathies, and overall cellular aging are marked by declining mitochondrial function and subsequent loss of multiple other cellular functions. For these reasons, optimized protocols are needed for visualization and quantification of mitochondria and their function and fitness. In budding yeast, mitochondria are intimately associated with the actin cytoskeleton and utilize actin for their movement and inheritance. This chapter describes optimal approaches for labeling mitochondria and the actin cytoskeleton in living budding yeast cells, for imaging the labeled cells, and for analyzing the resulting images.
Collapse
Affiliation(s)
- Ryo Higuchi-Sanabria
- Department of Pathology and Cell Biology, College of Physicians and Surgeons, Columbia University, 630 W. 168th Street, New York, NY, 10032, USA
| | - Theresa C Swayne
- Confocal and Specialized Microscopy Shared Resource, Herbert Irving Comprehensive Cancer Center, Columbia University, New York, NY, USA
| | - Istvan R Boldogh
- Department of Pathology and Cell Biology, College of Physicians and Surgeons, Columbia University, 630 W. 168th Street, New York, NY, 10032, USA
| | - Liza A Pon
- Department of Pathology and Cell Biology, College of Physicians and Surgeons, Columbia University, 630 W. 168th Street, New York, NY, 10032, USA. .,Confocal and Specialized Microscopy Shared Resource, Herbert Irving Comprehensive Cancer Center, Columbia University, New York, NY, USA.
| |
Collapse
|
106
|
Shou W. Acknowledging selection at sub-organismal levels resolves controversy on pro-cooperation mechanisms. eLife 2015; 4. [PMID: 26714105 PMCID: PMC4798966 DOI: 10.7554/elife.10106] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2015] [Accepted: 12/21/2015] [Indexed: 01/24/2023] Open
Abstract
Cooperators who pay a cost to produce publically-available benefits can be exploited by cheaters who do not contribute fairly. How might cooperation persist against cheaters? Two classes of mechanisms are known to promote cooperation: 'partner choice', where a cooperator preferentially interacts with cooperative over cheating partners; and 'partner fidelity feedback', where repeated interactions between individuals ensure that cheaters suffer as their cooperative partners languish (see, for example, Momeni et al., 2013). However when both mechanisms can act, differentiating them has generated controversy. Here, I resolve this controversy by noting that selection can operate on organismal and sub-organismal 'entities' such that partner fidelity feedback at sub-organismal level can appear as partner choice at organismal level. I also show that cooperation between multicellular eukaryotes and mitochondria is promoted by partner fidelity feedback and partner choice between sub-organismal entities, in addition to being promoted by partner fidelity feedback between hosts and symbionts, as was previously known.
Collapse
Affiliation(s)
- Wenying Shou
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, United States
| |
Collapse
|
107
|
Saarikangas J, Barral Y. Protein aggregates are associated with replicative aging without compromising protein quality control. eLife 2015; 4. [PMID: 26544680 PMCID: PMC4635334 DOI: 10.7554/elife.06197] [Citation(s) in RCA: 102] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2014] [Accepted: 10/19/2015] [Indexed: 12/12/2022] Open
Abstract
Differentiation of cellular lineages is facilitated by asymmetric segregation of fate determinants between dividing cells. In budding yeast, various aging factors segregate to the aging (mother)-lineage, with poorly understood consequences. In this study, we show that yeast mother cells form a protein aggregate during early replicative aging that is maintained as a single, asymmetrically inherited deposit over the remaining lifespan. Surprisingly, deposit formation was not associated with stress or general decline in proteostasis. Rather, the deposit-containing cells displayed enhanced degradation of cytosolic proteasome substrates and unimpaired clearance of stress-induced protein aggregates. Deposit formation was dependent on Hsp42, which collected non-random client proteins of the Hsp104/Hsp70-refolding machinery, including the prion Sup35. Importantly, loss of Hsp42 resulted in symmetric inheritance of its constituents and prolonged the lifespan of the mother cell. Together, these data suggest that protein aggregation is an early aging-associated differentiation event in yeast, having a two-faceted role in organismal fitness. DOI:http://dx.doi.org/10.7554/eLife.06197.001 Aging is a complex process. Studies involving a single-celled organism called budding yeast are commonly used to investigate the factors that contribute to aging. When these yeast cells divide, a small daughter cell buds out from a large mother cell. A mother cell has a limited lifespan and produces a finite number of daughter cells and then dies (a phenomenon referred to ‘replicative aging’). However, when a daughter cell forms, the daughter's age is reset to zero, giving it the full potential to produce new offspring. Previous research on budding yeast has shown that damaged or aggregated proteins accumulate in the mother cells but not the daughter cells, and that this accumulation of proteins contributes to shortening the lifespan of the mother cell. Furthermore, protein aggregation has also been associated with a number of age-related diseases in humans, including neurodegenerative disorders such as Alzheimer's and Parkinson's disease. However, it remains unclear how cells respond to protein aggregation that occurs during aging. Many studies that have previously investigated this question have relied on exposing cells to stressful conditions, such as high temperatures, in order to trigger proteins to aggregate. But now, Saarikangas and Barral have studied how proteins aggregate under normal, unstressed conditions in budding yeast as they age. The experiments revealed that most unstressed yeast cells develop a single deposit of aggregated proteins already during early aging. This age-associated structure proved to be a different type of response than the protein aggregation that occurs during stress. Furthermore, the deposit did not form as a consequence of the cell having obvious problems with folding its proteins, nor did the deposit hinder cells from coping with stressful conditions that trigger protein misfolding. Rather, this deposit supported the ability of the cell to degrade defective proteins. This suggests that the deposit represents an early adaptive response to aging, which might consequently provide aged cells some advantage over their younger counterparts. Saarikangas and Barral also found that this protein deposit was always retained in the mother cell and not passed onto the daughters at cell division. Further experiments showed that an enzyme called heat shock protein 42 was responsible for collecting target proteins and bring them together to form the single deposit. Reducing the levels of this enzyme prevented the deposit from forming and extended the lifespan of the mother cells. Thus, these findings suggest that mother cells collect harmful protein aggregates into a single deposit and prevent them from entering the daughter cells. Further work is needed to understand how the deposit is preferentially retained within the mother cell. DOI:http://dx.doi.org/10.7554/eLife.06197.002
Collapse
Affiliation(s)
- Juha Saarikangas
- Institute of Biochemistry, Eidgenössische Technische Hochschule Zürich, Zürich, Switzerland
| | - Yves Barral
- Institute of Biochemistry, Eidgenössische Technische Hochschule Zürich, Zürich, Switzerland
| |
Collapse
|
108
|
Knoblach B, Rachubinski RA. Motors, anchors, and connectors: orchestrators of organelle inheritance. Annu Rev Cell Dev Biol 2015; 31:55-81. [PMID: 26443192 DOI: 10.1146/annurev-cellbio-100814-125553] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Organelle inheritance is a process whereby organelles are actively distributed between dividing cells at cytokinesis. Much valuable insight into the molecular mechanisms of organelle inheritance has come from the analysis of asymmetrically dividing cells, which transport a portion of their organelles to the bud while retaining another portion in the mother cell. Common principles apply to the inheritance of all organelles, although individual organelles use specific factors for their partitioning. Inheritance factors can be classified as motors, which are required for organelle transport; anchors, which immobilize organelles at distinct cell structures; or connectors, which mediate the attachment of organelles to motors and anchors. Here, we provide an overview of recent advances in the field of organelle inheritance and highlight how motor, anchor, and connector molecules choreograph the segregation of a multicopy organelle, the peroxisome. We also discuss the role of organelle population control in the generation of cellular diversity.
Collapse
Affiliation(s)
- Barbara Knoblach
- Department of Cell Biology, University of Alberta, Edmonton, Alberta T6G 2H7, Canada;
| | - Richard A Rachubinski
- Department of Cell Biology, University of Alberta, Edmonton, Alberta T6G 2H7, Canada;
| |
Collapse
|
109
|
Systematic analysis of asymmetric partitioning of yeast proteome between mother and daughter cells reveals "aging factors" and mechanism of lifespan asymmetry. Proc Natl Acad Sci U S A 2015; 112:11977-82. [PMID: 26351681 DOI: 10.1073/pnas.1506054112] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Budding yeast divides asymmetrically, giving rise to a mother cell that progressively ages and a daughter cell with full lifespan. It is generally assumed that mother cells retain damaged, lifespan limiting materials ("aging factors") through asymmetric division. However, the identity of these aging factors and the mechanisms through which they limit lifespan remain poorly understood. Using a flow cytometry-based, high-throughput approach, we quantified the asymmetric partitioning of the yeast proteome between mother and daughter cells during cell division, discovering 74 mother-enriched and 60 daughter-enriched proteins. While daughter-enriched proteins are biased toward those needed for bud construction and genome maintenance, mother-enriched proteins are biased towards those localized in the plasma membrane and vacuole. Deletion of 23 of the 74 mother-enriched proteins leads to lifespan extension, a fraction that is about six times that of the genes picked randomly from the genome. Among these lifespan-extending genes, three are involved in endosomal sorting/endosome to vacuole transport, and three are nitrogen source transporters. Tracking the dynamic expression of specific mother-enriched proteins revealed that their concentration steadily increases in the mother cells as they age, but is kept relatively low in the daughter cells via asymmetric distribution. Our results suggest that some mother-enriched proteins may increase to a concentration that becomes deleterious and lifespan-limiting in aged cells, possibly by upsetting homeostasis or leading to aberrant signaling. Our study provides a comprehensive resource for analyzing asymmetric cell division and aging in yeast, which should also be valuable for understanding similar phenomena in other organisms.
Collapse
|
110
|
Kang WK, Kim YH, Kang HA, Kwon KS, Kim JY. Sir2 phosphorylation through cAMP-PKA and CK2 signaling inhibits the lifespan extension activity of Sir2 in yeast. eLife 2015; 4. [PMID: 26329457 PMCID: PMC4586308 DOI: 10.7554/elife.09709] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2015] [Accepted: 09/02/2015] [Indexed: 01/24/2023] Open
Abstract
Silent information regulator 2 (Sir2), an NAD+-dependent protein deacetylase, has been proposed to be a longevity factor that plays important roles in dietary restriction (DR)-mediated lifespan extension. In this study, we show that the Sir2's role for DR-mediated lifespan extension depends on cAMP-PKA and casein kinase 2 (CK2) signaling in yeast. Sir2 partially represses the transcription of lifespan-associated genes, such as PMA1 (encoding an H+-ATPase) and many ribosomal protein genes, through deacetylation of Lys 16 of histone H4 in the promoter regions of these genes. This repression is relieved by Sir2 S473 phosphorylation, which is mediated by active cAMP-PKA and CK2 signaling. Moderate DR increases the replicative lifespan of wild-type yeast but has no effect on that of yeast expressing the Sir2-S473E or S473A allele, suggesting that the effect of Sir2 on DR-mediated lifespan extension is negatively regulated by S473 phosphorylation. Our results demonstrate a mechanism by which Sir2 contributes to lifespan extension. DOI:http://dx.doi.org/10.7554/eLife.09709.001 We know that cutting calorie intake through a restricted diet can slow down the aging process and prolong the lives of many organisms ranging from yeast to mammals. Calorie restriction also has protective effects on various age-related diseases including neurodegenerative disorders, cardiovascular disease, and cancer. Many studies suggest that we may mimic the beneficial effects of calorie restriction by controlling the activities of some proteins involved in the aging process. An enzyme called Sir2 is required for calorie restriction to be able to increase lifespan. This enzyme modifies proteins called histones, which are used to package DNA inside cells. In yeast, Sir2 modifies the histones in such a way that the genes contained in that section of DNA are inactivated (or ‘silenced’). As the yeast cells age, the activity of Sir2 declines, which allows these genes to become active and contribute to the aging process. However, when yeast cells are grown in the presence of little sugar—which mimics caloric restriction—Sir2 is activated and this restores gene silencing. It is not clear how Sir2's ability to silence these genes contributes to prolonged lifespan. Kang et al. studied the role of Sir2 in yeast and observed that one of the genes that Sir2 inactivates is called PMA1. This gene encodes a protein that is known to restrict the lifespan of yeast cells. Further experiments show that other proteins attach or remove molecules called phosphate groups from Sir2 to regulate its activity. Sir2 is inactivated when a phosphate group is attached, and active in the absence of phosphate. Under a reduced diet, the proteins that add phosphate to Sir2 are inactive, which allows Sir2 to become active and reduce the expression of the PMA1 gene. These results show that Sir2 fine-tunes the expression of PMA1 and other age-related genes and that the attachment of phosphate groups to Sir2 by other proteins interferes with this regulation. The next challenges will be to identify the proteins responsible for attaching phosphate groups to Sir2, and to find out how they work. DOI:http://dx.doi.org/10.7554/eLife.09709.002
Collapse
Affiliation(s)
- Woo Kyu Kang
- Department of Microbiology and Molecular Biology, College of Bioscience and Biotechnology, Chungnam National University, Daejeon, Republic of Korea
| | - Yeong Hyeock Kim
- Department of Microbiology and Molecular Biology, College of Bioscience and Biotechnology, Chungnam National University, Daejeon, Republic of Korea
| | - Hyun Ah Kang
- Department of Life Science, Chung-Ang University, Seoul, Republic of Korea
| | - Ki-Sun Kwon
- Aging Intervention Research Center, Korea Research Institute of Bioscience and Biotechnology, Daejeon, Republic of Korea
| | - Jeong-Yoon Kim
- Department of Microbiology and Molecular Biology, College of Bioscience and Biotechnology, Chungnam National University, Daejeon, Republic of Korea
| |
Collapse
|
111
|
Jazwinski S. Mitochondria to nucleus signaling and the role of ceramide in its integration into the suite of cell quality control processes during aging. Ageing Res Rev 2015; 23:67-74. [PMID: 25555678 DOI: 10.1016/j.arr.2014.12.007] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2014] [Revised: 12/15/2014] [Accepted: 12/22/2014] [Indexed: 12/26/2022]
Abstract
Mitochondria to nucleus signaling has been the most extensively studied mode of inter-organelle communication. The first signaling pathway in this category of information transfer to be discovered was the retrograde response, with its own set of signal transduction proteins. The finding that this pathway compensates for mitochondrial dysfunction to extend the replicative lifespan of yeast cells has generated additional impetus for its study. This research has demonstrated crosstalk between the retrograde response and the target of rapamycin (TOR), small GTPase RAS, and high-osmolarity glycerol (HOG) pathways in yeast, all of which are key players in replicative lifespan. More recently, the retrograde response has been implicated in the diauxic shift and survival in stationary phase, extending its operation to the yeast chronological lifespan as well. In this capacity, the retrograde response may cooperate with other, related mitochondria to nucleus signaling pathways. Counterparts of the retrograde response are found in the roundworm, the fruit fly, the mouse, and even in human cells in tissue culture. The exciting realization that the retrograde response is embedded in the network of cellular quality control processes has emerged over the past few years. Most strikingly, it is closely integrated with autophagy and the selective brand of this quality control process, mitophagy. This coordination depends on TOR, and it engages ceramide/sphingolipid signaling. The yeast LAG1 ceramide synthase gene was the first longevity gene cloned as such, and its orthologs hyl-1 and hyl-2 determine worm lifespan. Thus, the involvement of ceramide signaling in quality control gives these findings cellular context. The retrograde response and ceramide are essential components of a lifespan maintenance process that likely evolved as a cytoprotective mechanism to defend the organism from diverse stressors.
Collapse
|
112
|
Arlia-Ciommo A, Piano A, Leonov A, Svistkova V, Titorenko VI. Quasi-programmed aging of budding yeast: a trade-off between programmed processes of cell proliferation, differentiation, stress response, survival and death defines yeast lifespan. Cell Cycle 2015; 13:3336-49. [PMID: 25485579 PMCID: PMC4614525 DOI: 10.4161/15384101.2014.965063] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Recent findings suggest that evolutionarily distant organisms share the key features of the aging process and exhibit similar mechanisms of its modulation by certain genetic, dietary and pharmacological interventions. The scope of this review is to analyze mechanisms that in the yeast Saccharomyces cerevisiae underlie: (1) the replicative and chronological modes of aging; (2) the convergence of these 2 modes of aging into a single aging process; (3) a programmed differentiation of aging cell communities in liquid media and on solid surfaces; and (4) longevity-defining responses of cells to some chemical compounds released to an ecosystem by other organisms populating it. Based on such analysis, we conclude that all these mechanisms are programs for upholding the long-term survival of the entire yeast population inhabiting an ecological niche; however, none of these mechanisms is a ʺprogram of agingʺ - i.e., a program for progressing through consecutive steps of the aging process.
Collapse
Key Words
- D, diauxic growth phase
- ERCs, extrachromosomal rDNA circles
- IPOD, insoluble protein deposit
- JUNQ, juxtanuclear quality control compartment
- L, logarithmic growth phase
- MBS, the mitochondrial back-signaling pathway
- MTC, the mitochondrial translation control signaling pathway
- NPCs, nuclear pore complexes
- NQ, non-quiescent cells
- PD, post-diauxic growth phase
- Q, quiescent cells
- ROS, reactive oxygen species
- RTG, the mitochondrial retrograde signaling pathway
- Ras/cAMP/PKA, the Ras family GTPase/cAMP/protein kinase A signaling pathway
- ST, stationary growth phase
- TOR/Sch9, the target of rapamycin/serine-threonine protein kinase Sch9 signaling pathway
- UPRER, the unfolded protein response pathway in the endoplasmic reticulum
- UPRmt, the unfolded protein response pathway in mitochondria
- cell growth and proliferation
- cell survival
- cellular aging
- ecosystems
- evolution
- longevity
- programmed cell death
- yeast
- yeast colony
- yeast replicative and chronological aging
Collapse
|
113
|
A Genetic Screen for Saccharomyces cerevisiae Mutants That Fail to Enter Quiescence. G3-GENES GENOMES GENETICS 2015; 5:1783-95. [PMID: 26068574 PMCID: PMC4528334 DOI: 10.1534/g3.115.019091] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/04/2022]
Abstract
Budding yeast begin the transition to quiescence by prolonging G1 and accumulating limited nutrients. They undergo asymmetric cell divisions, slow cellular expansion, acquire significant stress tolerance and construct elaborate cell walls. These morphologic changes give rise to quiescent (Q) cells, which can be distinguished from three other cell types in a stationary phase culture by flow cytometry. We have used flow cytometry to screen for genes that are required to obtain the quiescent cell fraction. We find that cell wall integrity is critical and these genes may help define quiescence-specific features of the cell wall. Genes required to evade the host innate immune response are common. These may be new targets for antifungal drugs. Acquired thermotolerance is also a common property, and we show that the stress-response transcription factors Msn2 and Msn4 promote quiescence. Many other pathways also contribute, including a subset of genes involved in autophagy, ubiquitin-mediated proteolysis, DNA replication, bud site selection, and cytokinesis.
Collapse
|
114
|
|
115
|
Pattabiraman S, Kaganovich D. Imperfect asymmetry: The mechanism governing asymmetric partitioning of damaged cellular components during mitosis. BIOARCHITECTURE 2015; 4:203-9. [PMID: 25941938 DOI: 10.1080/19490992.2015.1014213] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Aging is universally associated with organism-wide dysfunction and a decline in cellular fitness. From early development onwards, the efficiency of self-repair, energy production, and homeostasis all decrease. Due to the multiplicity of systems that undergo agingrelated decline, the mechanistic basis of organismal aging has been difficult to pinpoint. At the cellular level, however, recent work has provided important insight. Cellular aging is associated with the accumulation of several types of damage, in particular damage to the proteome and organelles. Groundbreaking studies have shown that replicative aging is the result of a rejuvenation mechanism that prevents the inheritance of damaged components during division, thereby confining the effects of aging to specific cells, while removing damage from others. Asymmetric inheritance of misfolded and aggregated proteins, as well as reduced mitochondria, has been shown in yeast. Until recently, however, it was not clear whether a similar mechanism operates in mammalian cells, which were thought to mostly divide symmetrically. Our group has recently shown that vimentin establishes mitotic polarity in immortalized mammalian cells, and mediates asymmetric partitioning of multiple factors through direct interaction. These findings prompt a provocative hypothesis: that intermediate filaments serve as asymmetric partitioning modules or "sponges" that, when expressed prior to mitosis, can "clean" emerging cells of the damage they have accumulated.
Collapse
Affiliation(s)
- Sundararaghavan Pattabiraman
- a Department of Cell and Developmental Biology ; Alexander Silberman Institute of Life Sciences; Hebrew University of Jerusalem ; Jerusalem , Israel
| | - Daniel Kaganovich
- a Department of Cell and Developmental Biology ; Alexander Silberman Institute of Life Sciences; Hebrew University of Jerusalem ; Jerusalem , Israel
| |
Collapse
|
116
|
Katajisto P, Döhla J, Chaffer CL, Pentinmikko N, Marjanovic N, Iqbal S, Zoncu R, Chen W, Weinberg RA, Sabatini DM. Stem cells. Asymmetric apportioning of aged mitochondria between daughter cells is required for stemness. Science 2015; 348:340-3. [PMID: 25837514 DOI: 10.1126/science.1260384] [Citation(s) in RCA: 371] [Impact Index Per Article: 41.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2014] [Accepted: 03/12/2015] [Indexed: 12/19/2022]
Abstract
By dividing asymmetrically, stem cells can generate two daughter cells with distinct fates. However, evidence is limited in mammalian systems for the selective apportioning of subcellular contents between daughters. We followed the fates of old and young organelles during the division of human mammary stemlike cells and found that such cells apportion aged mitochondria asymmetrically between daughter cells. Daughter cells that received fewer old mitochondria maintained stem cell traits. Inhibition of mitochondrial fission disrupted both the age-dependent subcellular localization and segregation of mitochondria and caused loss of stem cell properties in the progeny cells. Hence, mechanisms exist for mammalian stemlike cells to asymmetrically sort aged and young mitochondria, and these are important for maintaining stemness properties.
Collapse
Affiliation(s)
- Pekka Katajisto
- Whitehead Institute for Biomedical Research, Boston, MA 02142, USA. Department of Biology, Massachusetts Institute of Technology (MIT), Cambridge, MA 02139, USA. Howard Hughes Medical Institute, MIT, Cambridge, MA 02139, USA. Institute of Biotechnology, University of Helsinki, P.O. Box 00014, Helsinki, Finland.
| | - Julia Döhla
- Institute of Biotechnology, University of Helsinki, P.O. Box 00014, Helsinki, Finland
| | | | - Nalle Pentinmikko
- Institute of Biotechnology, University of Helsinki, P.O. Box 00014, Helsinki, Finland
| | - Nemanja Marjanovic
- Whitehead Institute for Biomedical Research, Boston, MA 02142, USA. Department of Biology, Massachusetts Institute of Technology (MIT), Cambridge, MA 02139, USA
| | - Sharif Iqbal
- Institute of Biotechnology, University of Helsinki, P.O. Box 00014, Helsinki, Finland
| | - Roberto Zoncu
- Whitehead Institute for Biomedical Research, Boston, MA 02142, USA. Department of Biology, Massachusetts Institute of Technology (MIT), Cambridge, MA 02139, USA. Howard Hughes Medical Institute, MIT, Cambridge, MA 02139, USA
| | - Walter Chen
- Whitehead Institute for Biomedical Research, Boston, MA 02142, USA. Department of Biology, Massachusetts Institute of Technology (MIT), Cambridge, MA 02139, USA. Howard Hughes Medical Institute, MIT, Cambridge, MA 02139, USA
| | - Robert A Weinberg
- Whitehead Institute for Biomedical Research, Boston, MA 02142, USA. Department of Biology, Massachusetts Institute of Technology (MIT), Cambridge, MA 02139, USA
| | - David M Sabatini
- Whitehead Institute for Biomedical Research, Boston, MA 02142, USA. Department of Biology, Massachusetts Institute of Technology (MIT), Cambridge, MA 02139, USA. Howard Hughes Medical Institute, MIT, Cambridge, MA 02139, USA. Broad Institute, Cambridge, MA 02142, USA. The David H. Koch Institute for Integrative Cancer Research at MIT, Cambridge, MA 02139, USA.
| |
Collapse
|
117
|
Smith J, Wright J, Schneider BL. A budding yeast's perspective on aging: the shape I'm in. Exp Biol Med (Maywood) 2015; 240:701-10. [PMID: 25819684 DOI: 10.1177/1535370215577584] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Aging is exemplified by progressive, deleterious changes that increase the probability of death. However, while the effects of age are easy to recognize, identification of the processes involved has proved to be much more difficult. Somewhat surprisingly, research using the budding yeast has had a profound impact on our current understanding of the mechanisms involved in aging. Herein, we examine the biological significance and implications surrounding the observation that genetic pathways involved in the modulation of aging and the determination of lifespan in yeast are highly complicated and conserved.
Collapse
Affiliation(s)
- Jessica Smith
- Department of Medical Education and Department of Cell Biology & Biochemistry, Texas Tech University Health Sciences Center, Lubbock, TX 79430, USA
| | - Jill Wright
- Department of Medical Education and Department of Cell Biology & Biochemistry, Texas Tech University Health Sciences Center, Lubbock, TX 79430, USA
| | - Brandt L Schneider
- Department of Medical Education and Department of Cell Biology & Biochemistry, Texas Tech University Health Sciences Center, Lubbock, TX 79430, USA
| |
Collapse
|
118
|
Mechanisms by which different functional states of mitochondria define yeast longevity. Int J Mol Sci 2015; 16:5528-54. [PMID: 25768339 PMCID: PMC4394491 DOI: 10.3390/ijms16035528] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2015] [Revised: 03/05/2015] [Accepted: 03/05/2015] [Indexed: 12/17/2022] Open
Abstract
Mitochondrial functionality is vital to organismal physiology. A body of evidence supports the notion that an age-related progressive decline in mitochondrial function is a hallmark of cellular and organismal aging in evolutionarily distant eukaryotes. Studies of the baker’s yeast Saccharomyces cerevisiae, a unicellular eukaryote, have led to discoveries of genes, signaling pathways and chemical compounds that modulate longevity-defining cellular processes in eukaryotic organisms across phyla. These studies have provided deep insights into mechanistic links that exist between different traits of mitochondrial functionality and cellular aging. The molecular mechanisms underlying the essential role of mitochondria as signaling organelles in yeast aging have begun to emerge. In this review, we discuss recent progress in understanding mechanisms by which different functional states of mitochondria define yeast longevity, outline the most important unanswered questions and suggest directions for future research.
Collapse
|
119
|
Knoblach B, Rachubinski RA. Sharing the cell's bounty - organelle inheritance in yeast. J Cell Sci 2015; 128:621-30. [PMID: 25616900 DOI: 10.1242/jcs.151423] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Eukaryotic cells replicate and partition their organelles between the mother cell and the daughter cell at cytokinesis. Polarized cells, notably the budding yeast Saccharomyces cerevisiae, are well suited for the study of organelle inheritance, as they facilitate an experimental dissection of organelle transport and retention processes. Much progress has been made in defining the molecular players involved in organelle partitioning in yeast. Each organelle uses a distinct set of factors - motor, anchor and adaptor proteins - that ensures its inheritance by future generations of cells. We propose that all organelles, regardless of origin or copy number, are partitioned by the same fundamental mechanism involving division and segregation. Thus, the mother cell keeps, and the daughter cell receives, their fair and equitable share of organelles. This mechanism of partitioning moreover facilitates the segregation of organelle fragments that are not functionally equivalent. In this Commentary, we describe how this principle of organelle population control affects peroxisomes and other organelles, and outline its implications for yeast life span and rejuvenation.
Collapse
Affiliation(s)
- Barbara Knoblach
- Department of Cell Biology, University of Alberta, Edmonton, AL T6G 2H7, Canada
| | | |
Collapse
|
120
|
Higuchi-Sanabria R, Pernice WMA, Vevea JD, Alessi Wolken DM, Boldogh IR, Pon LA. Role of asymmetric cell division in lifespan control in Saccharomyces cerevisiae. FEMS Yeast Res 2014; 14:1133-46. [PMID: 25263578 PMCID: PMC4270926 DOI: 10.1111/1567-1364.12216] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2014] [Revised: 09/22/2014] [Accepted: 09/22/2014] [Indexed: 11/29/2022] Open
Abstract
Aging determinants are asymmetrically distributed during cell division in S. cerevisiae, which leads to production of an immaculate, age-free daughter cell. During this process, damaged components are sequestered and retained in the mother cell, and higher functioning organelles and rejuvenating factors are transported to and/or enriched in the bud. Here, we will describe the key quality control mechanisms in budding yeast that contribute to asymmetric cell division of aging determinants including mitochondria, endoplasmic reticulum (ER), vacuoles, extrachromosomal rDNA circles (ERCs), and protein aggregates.
Collapse
Affiliation(s)
- Ryo Higuchi-Sanabria
- Department of Pathology and Cell Biology, College of Physicians and Surgeons, Columbia University, New York, NY, USA
| | | | | | | | | | | |
Collapse
|
121
|
Zhou C, Slaughter BD, Unruh JR, Guo F, Yu Z, Mickey K, Narkar A, Ross RT, McClain M, Li R. Organelle-based aggregation and retention of damaged proteins in asymmetrically dividing cells. Cell 2014; 159:530-42. [PMID: 25417105 DOI: 10.1016/j.cell.2014.09.026] [Citation(s) in RCA: 168] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2014] [Revised: 08/07/2014] [Accepted: 09/10/2014] [Indexed: 12/26/2022]
Abstract
Aggregation of damaged or misfolded proteins is a protective mechanism against proteotoxic stress, abnormalities of which underlie many aging-related diseases. Here, we show that in asymmetrically dividing yeast cells, aggregation of cytosolic misfolded proteins does not occur spontaneously but requires new polypeptide synthesis and is restricted to the surface of ER, which harbors the majority of active translation sites. Protein aggregates formed on ER are frequently also associated with or are later captured by mitochondria, greatly constraining aggregate mobility. During mitosis, aggregates are tethered to well-anchored maternal mitochondria, whereas mitochondria acquired by the bud are largely free of aggregates. Disruption of aggregate-mitochondria association resulted in increased mobility and leakage of mother-accumulated aggregates into the bud. Cells with advanced replicative age exhibit gradual decline of aggregates-mitochondria association, likely contributing to their diminished ability to rejuvenate through asymmetric cell division.
Collapse
Affiliation(s)
- Chuankai Zhou
- Stowers Institute for Medical Research, 1000 East 50(th) Street, Kansas City, MO 64110, USA; Department of Molecular and Integrative Physiology, University of Kansas Medical Center, 3901 Rainbow Boulevard, Kansas City, KS 66160, USA
| | - Brian D Slaughter
- Stowers Institute for Medical Research, 1000 East 50(th) Street, Kansas City, MO 64110, USA
| | - Jay R Unruh
- Stowers Institute for Medical Research, 1000 East 50(th) Street, Kansas City, MO 64110, USA
| | - Fengli Guo
- Stowers Institute for Medical Research, 1000 East 50(th) Street, Kansas City, MO 64110, USA
| | - Zulin Yu
- Stowers Institute for Medical Research, 1000 East 50(th) Street, Kansas City, MO 64110, USA
| | - Kristen Mickey
- Department of Pharmacolgy, Toxicology, and Therapeutics, University of Kansas Medical Center, 3901 Rainbow Boulevard, Kansas City, KS 66160, USA
| | - Akshay Narkar
- Stowers Institute for Medical Research, 1000 East 50(th) Street, Kansas City, MO 64110, USA; Department of Molecular and Integrative Physiology, University of Kansas Medical Center, 3901 Rainbow Boulevard, Kansas City, KS 66160, USA
| | - Rhonda Trimble Ross
- Stowers Institute for Medical Research, 1000 East 50(th) Street, Kansas City, MO 64110, USA
| | - Melainia McClain
- Stowers Institute for Medical Research, 1000 East 50(th) Street, Kansas City, MO 64110, USA
| | - Rong Li
- Stowers Institute for Medical Research, 1000 East 50(th) Street, Kansas City, MO 64110, USA; Department of Molecular and Integrative Physiology, University of Kansas Medical Center, 3901 Rainbow Boulevard, Kansas City, KS 66160, USA.
| |
Collapse
|
122
|
Henderson KA, Hughes AL, Gottschling DE. Mother-daughter asymmetry of pH underlies aging and rejuvenation in yeast. eLife 2014; 3:e03504. [PMID: 25190112 PMCID: PMC4175738 DOI: 10.7554/elife.03504] [Citation(s) in RCA: 102] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2014] [Accepted: 09/03/2014] [Indexed: 12/20/2022] Open
Abstract
Replicative aging in yeast is asymmetric–mother cells age but their daughter cells are rejuvenated. Here we identify an asymmetry in pH between mother and daughter cells that underlies aging and rejuvenation. Cytosolic pH increases in aging mother cells, but is more acidic in daughter cells. This is due to the asymmetric distribution of the major regulator of cytosolic pH, the plasma membrane proton ATPase (Pma1). Pma1 accumulates in aging mother cells, but is largely absent from nascent daughter cells. We previously found that acidity of the vacuole declines in aging mother cells and limits lifespan, but that daughter cell vacuoles re-acidify. We find that Pma1 activity antagonizes mother cell vacuole acidity by reducing cytosolic protons. However, the inherent asymmetry of Pma1 increases cytosolic proton availability in daughter cells and facilitates vacuole re-acidification and rejuvenation. DOI:http://dx.doi.org/10.7554/eLife.03504.001 Aging is a part of life—but its biological basis and, in particular, how aged cells give rise to young offspring (or progeny) has not been clearly established for any organism. Budding yeast is a microorganism that is a valuable model to understand aging in more complex organisms like humans. Budding yeast cells undergo a process called ‘replicative aging’, meaning that each yeast mother cell produces a set number of daughter cells in her lifetime. However, when daughter cells arise from an aging mother cell, the daughter's age is ‘reset to zero’. How mother cells age, and how their daughters are rejuvenated, are questions that have been studied for decades. Previously, researchers discovered that a mother cell's vacuole (an acidic compartment that stores important molecules that can become toxic) becomes less acidic as the mother cell ages. Daughter cells, on the other hand, have very acidic vacuoles, which was linked to their renewed lifespans. However, the mechanism behind this difference in the acidity of the vacuole between mother and daughter cells was unknown. Now, Henderson et al. have found that a protein (called Pma1), which is found at the cell surface and pumps protons out of the cell, is present in mother cells but not in their newly-formed daughter cells. Furthermore, the Pma1 protein also accumulates as mother cells age. By pumping protons out of the cell, Pma1 effectively reduces the number of protons available to acidify the vacuole in the mother cell. However, because at first the daughter does not have Pma1, there are still plenty of protons inside the cell to acidify the vacuole. When Henderson et al. reduced the activity of Pma1 in mother cells, the entire cell became more acidic, and so did their vacuoles. Conversely daughter cells engineered to have more Pma1 were less acidic and had less acidic vacuoles than normal. Henderson et al. next asked whether reducing Pma1 activity to create a more acidic cell, could extend the lifespan of cells, and found that indeed cells with less Pma1 activity lived longer. As such, these findings indicate that an asymmetry in the acidity of the cell—caused by unequal levels of the Pma1 protein—contributes to reducing the lifespan of the mother cell and to rejuvenating the daughter cell. Thus Henderson et al. have identified one of the earliest events in the cellular aging process in budding yeast. Their findings suggest that an imbalance in an activity that is normally essential for cell survival (in this case, the activity of Pma1) can have long-term consequences for the cell that lead to aging. DOI:http://dx.doi.org/10.7554/eLife.03504.002
Collapse
Affiliation(s)
- Kiersten A Henderson
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, United States
| | - Adam L Hughes
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, United States
| | - Daniel E Gottschling
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, United States
| |
Collapse
|
123
|
Abstract
During yeast cytokinesis an aged mother cell gives rise to an immaculate daughter cell. A new study now demonstrates that this rejuvenation encompasses a novel Sir2- and actin-cable-dependent filtering process that prevents feeble mitochondria from entering the daughter cell.
Collapse
Affiliation(s)
- Thomas Nyström
- Department of Chemistry and Molecular Biology, University of Gothenburg, Medicinaregatan 9C, S-413 90 Göteborg, Sweden.
| |
Collapse
|
124
|
Van Vranken JG, Bricker DK, Dephoure N, Gygi SP, Cox JE, Thummel CS, Rutter J. SDHAF4 promotes mitochondrial succinate dehydrogenase activity and prevents neurodegeneration. Cell Metab 2014; 20:241-52. [PMID: 24954416 PMCID: PMC4126880 DOI: 10.1016/j.cmet.2014.05.012] [Citation(s) in RCA: 80] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/07/2014] [Revised: 03/28/2014] [Accepted: 04/28/2014] [Indexed: 02/05/2023]
Abstract
Succinate dehydrogenase (SDH) occupies a central place in cellular energy production, linking the tricarboxylic cycle with the electron transport chain. As a result, a subset of cancers and neuromuscular disorders result from mutations affecting any of the four SDH structural subunits or either of two known SDH assembly factors. Herein we characterize an evolutionarily conserved SDH assembly factor designated Sdh8/SDHAF4, using yeast, Drosophila, and mammalian cells. Sdh8 interacts specifically with the catalytic Sdh1 subunit in the mitochondrial matrix, facilitating its association with Sdh2 and the subsequent assembly of the SDH holocomplex. These roles for Sdh8 are critical for preventing motility defects and neurodegeneration in Drosophila as well as the excess ROS generated by free Sdh1. These studies provide insights into the mechanisms by which SDH is assembled and raise the possibility that some forms of neuromuscular disease may be associated with mutations that affect this SDH assembly factor.
Collapse
Affiliation(s)
- Jonathan G Van Vranken
- Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, UT 84112, USA
| | - Daniel K Bricker
- Department of Human Genetics, University of Utah School of Medicine, Salt Lake City, UT 84112, USA
| | - Noah Dephoure
- Department of Cell Biology, Harvard University Medical School, Boston, MA 02115, USA
| | - Steven P Gygi
- Department of Cell Biology, Harvard University Medical School, Boston, MA 02115, USA
| | - James E Cox
- Metabolomics Core Research Facility, University of Utah School of Medicine, Salt Lake City, UT 84112, USA
| | - Carl S Thummel
- Department of Human Genetics, University of Utah School of Medicine, Salt Lake City, UT 84112, USA.
| | - Jared Rutter
- Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, UT 84112, USA.
| |
Collapse
|
125
|
Petralia RS, Mattson MP, Yao PJ. Aging and longevity in the simplest animals and the quest for immortality. Ageing Res Rev 2014; 16:66-82. [PMID: 24910306 DOI: 10.1016/j.arr.2014.05.003] [Citation(s) in RCA: 64] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2014] [Revised: 05/08/2014] [Accepted: 05/22/2014] [Indexed: 12/12/2022]
Abstract
Here we review the examples of great longevity and potential immortality in the earliest animal types and contrast and compare these to humans and other higher animals. We start by discussing aging in single-celled organisms such as yeast and ciliates, and the idea of the immortal cell clone. Then we describe how these cell clones could become organized into colonies of different cell types that lead to multicellular animal life. We survey aging and longevity in all of the basal metazoan groups including ctenophores (comb jellies), sponges, placozoans, cnidarians (hydras, jellyfish, corals and sea anemones) and myxozoans. Then we move to the simplest bilaterian animals (with a head, three body cell layers, and bilateral symmetry), the two phyla of flatworms. A key determinant of longevity and immortality in most of these simple animals is the large numbers of pluripotent stem cells that underlie the remarkable abilities of these animals to regenerate and rejuvenate themselves. Finally, we discuss briefly the evolution of the higher bilaterians and how longevity was reduced and immortality lost due to attainment of greater body complexity and cell cycle strategies that protect these complex organisms from developing tumors. We also briefly consider how the evolution of multiple aging-related mechanisms/pathways hinders our ability to understand and modify the aging process in higher organisms.
Collapse
|
126
|
Carmona-Gutierrez D, Büttner S. The many ways to age for a single yeast cell. Yeast 2014; 31:289-98. [PMID: 24842537 PMCID: PMC4140606 DOI: 10.1002/yea.3020] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2014] [Revised: 05/07/2014] [Accepted: 05/09/2014] [Indexed: 12/17/2022] Open
Abstract
The identification and characterization of the molecular determinants governing ageing represents the key to counteracting age-related diseases and eventually prolonging our health span. A large number of fundamental insights into the ageing process have been provided by research into the budding yeast Saccharomyces cerevisiae, which couples a wide array of technical advantages with a high degree of genetic, proteomic and mechanistic conservation. Indeed, this unicellular organism harbours regulatory pathways, such as those related to programmed cell death or nutrient signalling, that are crucial for ageing control and are reminiscent of other eukaryotes, including mammals. Here, we summarize and discuss three different paradigms of yeast ageing: replicative, chronological and colony ageing. We address their physiological relevance as well as the specific and common characteristics and regulators involved, providing an overview of the network underlying ageing in one of the most important eukaryotic model organisms.
Collapse
|
127
|
Abstract
In a majority of cell types, mitochondria form highly dynamic, tubular networks. Maintaining the shape of this complex network is critical for both mitochondrial and cellular function and involves the activities of mitochondrial division, fusion, motility, and tethering. Recent studies have advanced our understanding of the molecular mechanisms underlying these conserved activities and their integration with cellular needs.
Collapse
Affiliation(s)
- Laura L Lackner
- Department of Molecular Biosciences, Northwestern University, 2205 Tech Drive Hogan 2-100, Evanston, IL 60208, USA.
| |
Collapse
|
128
|
Nyström T, Liu B. The mystery of aging and rejuvenation - a budding topic. Curr Opin Microbiol 2014; 18:61-7. [PMID: 24631930 DOI: 10.1016/j.mib.2014.02.003] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2013] [Revised: 02/11/2014] [Accepted: 02/13/2014] [Indexed: 11/30/2022]
Abstract
In the process of yeast budding, an aged and deteriorated mother cell gives rise to a youthful and pristine daughter cell. This remarkable event offers a tractable model system for identifying factors affecting life expectancy and it has been established that multiple aging factors operate in parallel. Herein, we will highlight the identity of such aging factors, how they are asymmetrically segregated, and whether the knowledge of their deteriorating effects might be utilized to approach cellular and tissue rejuvenation in metazoans, including humans.
Collapse
Affiliation(s)
- Thomas Nyström
- Department of Chemistry and Molecular Biology, University of Gothenburg, Medicinaregatan 9C, S-413 90 Göteborg, Sweden.
| | - Beidong Liu
- Department of Chemistry and Molecular Biology, University of Gothenburg, Medicinaregatan 9C, S-413 90 Göteborg, Sweden
| |
Collapse
|
129
|
Denoth Lippuner A, Julou T, Barral Y. Budding yeast as a model organism to study the effects of age. FEMS Microbiol Rev 2014; 38:300-25. [PMID: 24484434 DOI: 10.1111/1574-6976.12060] [Citation(s) in RCA: 134] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2013] [Revised: 12/13/2013] [Accepted: 01/06/2014] [Indexed: 12/20/2022] Open
Abstract
Although a budding yeast culture can be propagated eternally, individual yeast cells age and eventually die. The detailed knowledge of this unicellular eukaryotic species as well as the powerful tools developed to study its physiology makes budding yeast an ideal model organism to study the mechanisms involved in aging. Considering both detrimental and positive aspects of age, we review changes occurring during aging both at the whole-cell level and at the intracellular level. The possible mechanisms allowing old cells to produce rejuvenated progeny are described in terms of accumulation and inheritance of aging factors. Based on the dynamic changes associated with age, we distinguish different stages of age: early age, during which changes do not impair cell growth; intermediate age, during which aging factors start to accumulate; and late age, which corresponds to the last divisions before death. For each aging factor, we examine its asymmetric segregation and whether it plays a causal role in aging. Using the example of caloric restriction, we describe how the aging process can be modulated at different levels and how changes in different organelles might interplay with each other. Finally, we discuss the beneficial aspects that might be associated with age.
Collapse
|
130
|
Strandkvist C, Juul J, Bendtsen KM. Asymmetric segregation of damaged cellular components in spatially structured multicellular organisms. PLoS One 2014; 9:e87917. [PMID: 24551071 PMCID: PMC3923766 DOI: 10.1371/journal.pone.0087917] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2013] [Accepted: 01/01/2014] [Indexed: 11/18/2022] Open
Abstract
The asymmetric distribution of damaged cellular components has been observed in species ranging from fission yeast to humans. To study the potential advantages of damage segregation, we have developed a mathematical model describing ageing mammalian tissue, that is, a multicellular system of somatic cells that do not rejuvenate at cell division. To illustrate the applicability of the model, we specifically consider damage incurred by mutations to mitochondrial DNA, which are thought to be implicated in the mammalian ageing process. We show analytically that the asymmetric distribution of damaged cellular components reduces the overall damage level and increases the longevity of the cell population. Motivated by the experimental reports of damage segregation in human embryonic stem cells, dividing symmetrically with respect to cell-fate, we extend the model to consider spatially structured systems of cells. Imposing spatial structure reduces, but does not eliminate, the advantage of asymmetric division over symmetric division. The results suggest that damage partitioning could be a common strategy for reducing the accumulation of damage in a wider range of cell types than previously thought.
Collapse
Affiliation(s)
| | - Jeppe Juul
- University of Copenhagen, Niels Bohr Institute, Copenhagen, Denmark
| | | |
Collapse
|
131
|
Wierman MB, Smith JS. Yeast sirtuins and the regulation of aging. FEMS Yeast Res 2014; 14:73-88. [PMID: 24164855 PMCID: PMC4365911 DOI: 10.1111/1567-1364.12115] [Citation(s) in RCA: 82] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2013] [Revised: 10/09/2013] [Accepted: 10/13/2013] [Indexed: 11/29/2022] Open
Abstract
The sirtuins are a phylogenetically conserved family of NAD(+) -dependent protein deacetylases that consume one molecule of NAD(+) for every deacetylated lysine side chain. Their requirement for NAD(+) potentially makes them prone to regulation by fluctuations in NAD(+) or biosynthesis intermediates, thus linking them to cellular metabolism. The Sir2 protein from Saccharomyces cerevisiae is the founding sirtuin family member and has been well characterized as a histone deacetylase that functions in transcriptional silencing of heterochromatin domains and as a pro-longevity factor for replicative life span (RLS), defined as the number of times a mother cell divides (buds) before senescing. Deleting SIR2 shortens RLS, while increased gene dosage causes extension. Furthermore, Sir2 has been implicated in mediating the beneficial effects of caloric restriction (CR) on life span, not only in yeast, but also in higher eukaryotes. While this paradigm has had its share of disagreements and debate, it has also helped rapidly drive the aging research field forward. S. cerevisiae has four additional sirtuins, Hst1, Hst2, Hst3, and Hst4. This review discusses the function of Sir2 and the Hst homologs in replicative aging and chronological aging, and also addresses how the sirtuins are regulated in response to environmental stresses such as CR.
Collapse
Affiliation(s)
- Margaret B Wierman
- Department of Biochemistry and Molecular Genetics, University of Virginia School of Medicine, Charlottesville, VA, USA
| | | |
Collapse
|
132
|
Sorokin MI, Knorre DA, Severin FF. Early manifestations of replicative aging in the yeast Saccharomyces cerevisiae. MICROBIAL CELL 2014; 1:37-42. [PMID: 28357208 PMCID: PMC5349164 DOI: 10.15698/mic2014.01.122] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
The yeast Saccharomyces cerevisiae is successfully used as a model organism to find genes responsible for lifespan control of higher organisms. As functional decline of higher eukaryotes can start as early as one quarter of the average lifespan, we asked whether S. cerevisiae can be used to model this manifestation of aging. While the average replicative lifespan of S. cerevisiae mother cells ranges between 15 and 30 division cycles, we found that resistances to certain stresses start to decrease much earlier. Looking into the mechanism, we found that knockouts of genes responsible for mitochondria-to-nucleus (retrograde) signaling, RTG1 or RTG3, significantly decrease the resistance of cells that generated more than four daughters, but not of the younger ones. We also found that even young mother cells frequently contain mitochondria with heterogeneous transmembrane potential and that the percentage of such cells correlates with replicative age. Together, these facts suggest that retrograde signaling starts to malfunction in relatively young cells, leading to accumulation of heterogeneous mitochondria within one cell. The latter may further contribute to a decline in stress resistances.
Collapse
Affiliation(s)
- Maksim I Sorokin
- Faculty of Bioengineering and Bioinformatics, Moscow State University, Vorobyevy Gory 1, Moscow, Russia. ; Institute of Mitoengineering, Moscow State University, Vorobyevy Gory 1, Moscow, Russia
| | - Dmitry A Knorre
- Belozersky Institute of Physico-Chemical Biology, Moscow State University, Vorobyevy Gory 1, Moscow, Russia. ; Institute of Mitoengineering, Moscow State University, Vorobyevy Gory 1, Moscow, Russia
| | - Fedor F Severin
- Belozersky Institute of Physico-Chemical Biology, Moscow State University, Vorobyevy Gory 1, Moscow, Russia. ; Institute of Mitoengineering, Moscow State University, Vorobyevy Gory 1, Moscow, Russia
| |
Collapse
|
133
|
Fehrmann S, Paoletti C, Goulev Y, Ungureanu A, Aguilaniu H, Charvin G. Aging yeast cells undergo a sharp entry into senescence unrelated to the loss of mitochondrial membrane potential. Cell Rep 2013; 5:1589-99. [PMID: 24332850 DOI: 10.1016/j.celrep.2013.11.013] [Citation(s) in RCA: 81] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2013] [Revised: 10/23/2013] [Accepted: 11/07/2013] [Indexed: 11/26/2022] Open
Abstract
In budding yeast, a mother cell can produce a finite number of daughter cells before it stops dividing and dies. Such entry into senescence is thought to result from a progressive decline in physiological function, including a loss of mitochondrial membrane potential (ΔΨ). Here, we developed a microfluidic device to monitor the dynamics of cell division and ΔΨ in real time at single-cell resolution. We show that cells do not enter senescence gradually but rather undergo an abrupt transition to a slowly dividing state. Moreover, we demonstrate that the decline in ΔΨ, which is observed only in a fraction of cells, is not responsible for entry into senescence. Rather, the loss of ΔΨ is an age-independent and heritable process that leads to clonal senescence and is therefore incompatible with daughter cell rejuvenation. These results emphasize the importance of quantitative single-cell measurements to decipher the causes of cellular aging.
Collapse
Affiliation(s)
- Steffen Fehrmann
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, 1 Rue Laurent Fries, 67400 Illkirch Cedex, France
| | - Camille Paoletti
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, 1 Rue Laurent Fries, 67400 Illkirch Cedex, France
| | - Youlian Goulev
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, 1 Rue Laurent Fries, 67400 Illkirch Cedex, France
| | | | - Hugo Aguilaniu
- LBMC, ENS Lyon, 46 Allée d'Italie, 69364 Lyon Cedex 07, France
| | - Gilles Charvin
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, 1 Rue Laurent Fries, 67400 Illkirch Cedex, France.
| |
Collapse
|
134
|
Higuchi R, Vevea JD, Swayne TC, Chojnowski R, Hill V, Boldogh IR, Pon LA. Actin dynamics affect mitochondrial quality control and aging in budding yeast. Curr Biol 2013; 23:2417-22. [PMID: 24268413 DOI: 10.1016/j.cub.2013.10.022] [Citation(s) in RCA: 86] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2013] [Revised: 09/27/2013] [Accepted: 10/09/2013] [Indexed: 11/24/2022]
Abstract
Actin cables of budding yeast are bundles of F-actin that extend from the bud tip or neck to the mother cell tip, serve as tracks for bidirectional cargo transport, and undergo continuous movement from buds toward mother cells [1]. This movement, retrograde actin cable flow (RACF), is similar to retrograde actin flow in lamellipodia, growth cones, immunological synapses, dendritic spines, and filopodia [2-5]. In all cases, actin flow is driven by the push of actin polymerization and assembly at the cell cortex, and myosin-driven pulling forces deeper within the cell [6-10]. Therefore, for movement and inheritance from mothers to buds, mitochondria must "swim upstream" against the opposing force of RACF [11]. We find that increasing RACF rates results in increased fitness of mitochondria inherited by buds and that the increase in mitochondrial fitness leads to extended replicative lifespan and increased cellular healthspan. The sirtuin SIR2 is required for normal RACF and mitochondrial fitness, and increasing RACF rates in sir2Δ cells increases mitochondrial fitness and cellular healthspan but does not affect replicative lifespan. These studies support the model that RACF serves as a filter for segregation of fit from less-fit mitochondria during inheritance, which controls cellular lifespan and healthspan. They also support a role for Sir2p in these processes.
Collapse
Affiliation(s)
- Ryo Higuchi
- Department of Pathology and Cell Biology, College of Physicians and Surgeons, Columbia University, 630 W. 168(th) Street, New York, NY 10032, USA
| | | | | | | | | | | | | |
Collapse
|
135
|
Bhandari P, Song M, Chen Y, Burelle Y, Dorn GW. Mitochondrial contagion induced by Parkin deficiency in Drosophila hearts and its containment by suppressing mitofusin. Circ Res 2013; 114:257-65. [PMID: 24192653 DOI: 10.1161/circresaha.114.302734] [Citation(s) in RCA: 101] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
RATIONALE Dysfunctional Parkin-mediated mitophagic culling of senescent or damaged mitochondria is a major pathological process underlying Parkinson disease and a potential genetic mechanism of cardiomyopathy. Despite epidemiological associations between Parkinson disease and heart failure, the role of Parkin and mitophagic quality control in maintaining normal cardiac homeostasis is poorly understood. OBJECTIVE We used germline mutants and cardiac-specific RNA interference to interrogate Parkin regulation of cardiomyocyte mitochondria and examine functional crosstalk between mitophagy and mitochondrial dynamics in Drosophila heart tubes. METHODS AND RESULTS Transcriptional profiling of Parkin knockout mouse hearts revealed compensatory upregulation of multiple related E3 ubiquitin ligases. Because Drosophila lack most of these redundant genes, we examined heart tubes of parkin knockout flies and observed accumulation of enlarged hollow donut mitochondria with dilated cardiomyopathy, which could be rescued by cardiomyocyte-specific Parkin expression. Identical abnormalities were induced by cardiomyocyte-specific Parkin suppression using 2 different inhibitory RNAs. Parkin-deficient cardiomyocyte mitochondria exhibited dysmorphology, depolarization, and reactive oxygen species generation without calcium cycling abnormalities, pointing to a primary mitochondrial defect. Suppressing cardiomyocyte mitochondrial fusion in Parkin-deficient fly heart tubes completely prevented the cardiomyopathy and corrected mitochondrial dysfunction without normalizing mitochondrial dysmorphology, demonstrating a central role for mitochondrial fusion in the cardiomyopathy provoked by impaired mitophagy. CONCLUSIONS Parkin deficiency and resulting mitophagic disruption produces cardiomyopathy in part by contamination of the cardiomyocyte mitochondrial pool through fusion between improperly retained dysfunctional/senescent and normal mitochondria. Limiting mitochondrial contagion by inhibiting organelle fusion shows promise for minimizing organ dysfunction produced by defective mitophagic signaling.
Collapse
Affiliation(s)
- Poonam Bhandari
- From the Center for Pharmacogenomics, Department of Internal Medicine, Washington University School of Medicine, St Louis, MO (P.B., M.S., Y.C., G.W.D.); and Department of Biomedical Sciences, University of Montreal, Quebec, Canada (Y.B.)
| | | | | | | | | |
Collapse
|
136
|
McInnes J, Rehders M, McFaline-Figueroa JR, Brix K, Pon LA, Nevoigt E. Defects in mitochondrial distribution during the prolonged lag phase of Saccharomyces cerevisiae preceding growth in glycerol as the sole source of carbon. FEMS Yeast Res 2013; 13:706-10. [PMID: 24020807 DOI: 10.1111/1567-1364.12085] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2013] [Accepted: 09/01/2013] [Indexed: 01/01/2023] Open
Abstract
The Saccharomyces cerevisiae strain CBS6412 has been shown to be able to grow in synthetic medium containing glycerol as the sole carbon source, conditions under which laboratory strains such as CEN.PK and S288c cannot grow. Nonetheless, this strain exhibits a lag phase of c. 30-40 h following transition to glycerol medium. As mitochondria play a critical role in the dissimilation of the respiratory carbon source glycerol, we investigated mitochondrial function and dynamics throughout the lag phase using mitochondria-targeted roGFP, a redox-sensitive GFP variant. We found that following transition to glycerol medium, mitochondria become more oxidizing, accumulate near the bud neck, and exhibit decreased inheritance into daughter cells. Directly preceding entry into exponential growth phase, mitochondria become more reducing, mitochondrial accumulations at the bud neck decrease, and inheritance of mitochondria into daughter cells is restored.
Collapse
Affiliation(s)
- Joseph McInnes
- School of Engineering and Science, Research Center MOLIFE - Molecular Life Science, Jacobs University Bremen, Bremen, Germany
| | | | | | | | | | | |
Collapse
|
137
|
Wasko BM, Kaeberlein M. Yeast replicative aging: a paradigm for defining conserved longevity interventions. FEMS Yeast Res 2013; 14:148-59. [PMID: 24119093 DOI: 10.1111/1567-1364.12104] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2013] [Revised: 08/22/2013] [Accepted: 09/26/2013] [Indexed: 12/15/2022] Open
Abstract
The finite replicative life span of budding yeast mother cells was demonstrated as early as 1959, but the idea that budding yeast could be used to model aging of multicellular eukaryotes did not enter the scientific mainstream until relatively recently. Despite continued skepticism by some, there are now abundant data that several interventions capable of extending yeast replicative life span have a similar effect in multicellular eukaryotes including nematode worms, fruit flies, and rodents. In particular, dietary restriction, mTOR signaling, and sirtuins are among the most studied longevity interventions in the field. Here, we describe key conserved longevity pathways in yeast and discuss relationships that may help explain how such broad conservation of aging processes could have evolved.
Collapse
Affiliation(s)
- Brian M Wasko
- Department of Pathology, University of Washington, Seattle, WA, USA
| | | |
Collapse
|
138
|
Westermann B. Mitochondrial inheritance in yeast. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2013; 1837:1039-46. [PMID: 24183694 DOI: 10.1016/j.bbabio.2013.10.005] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/16/2013] [Revised: 10/08/2013] [Accepted: 10/22/2013] [Indexed: 11/25/2022]
Abstract
Mitochondria are the site of oxidative phosphorylation, play a key role in cellular energy metabolism, and are critical for cell survival and proliferation. The propagation of mitochondria during cell division depends on replication and partitioning of mitochondrial DNA, cytoskeleton-dependent mitochondrial transport, intracellular positioning of the organelle, and activities coordinating these processes. Budding yeast Saccharomyces cerevisiae has proven to be a valuable model organism to study the mechanisms that drive segregation of the mitochondrial genome and determine mitochondrial partitioning and behavior in an asymmetrically dividing cell. Here, I review past and recent advances that identified key components and cellular pathways contributing to mitochondrial inheritance in yeast. This article is part of a Special Issue entitled: 18th European Bioenergetic Conference. Guest Editors: Manuela Pereira and Miguel Teixeira.
Collapse
|
139
|
Li L, Miles S, Melville Z, Prasad A, Bradley G, Breeden LL. Key events during the transition from rapid growth to quiescence in budding yeast require posttranscriptional regulators. Mol Biol Cell 2013; 24:3697-709. [PMID: 24088570 PMCID: PMC3842996 DOI: 10.1091/mbc.e13-05-0241] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
The transition to quiescence in budding yeast involves highly asymmetric cell divisions and elaborate cell wall fortifications that can be followed by flow cytometry. Posttranscriptional regulators Ssd1V, Mpt5, and Lsm1 are important for this transition. Yeast that naturally exhaust the glucose from their environment differentiate into three distinct cell types distinguishable by flow cytometry. Among these is a quiescent (Q) population, which is so named because of its uniform but readily reversed G1 arrest, its fortified cell walls, heat tolerance, and longevity. Daughter cells predominate in Q-cell populations and are the longest lived. The events that differentiate Q cells from nonquiescent (nonQ) cells are initiated within hours of the diauxic shift, when cells have scavenged all the glucose from the media. These include highly asymmetric cell divisions, which give rise to very small daughter cells. These daughters modify their cell walls by Sed1- and Ecm33-dependent and dithiothreitol-sensitive mechanisms that enhance Q-cell thermotolerance. Ssd1 speeds Q-cell wall assembly and enables mother cells to enter this state. Ssd1 and the related mRNA-binding protein Mpt5 play critical overlapping roles in Q-cell formation and longevity. These proteins deliver mRNAs to P-bodies, and at least one P-body component, Lsm1, also plays a unique role in Q-cell longevity. Cells lacking Lsm1 and Ssd1 or Mpt5 lose viability under these conditions and fail to enter the quiescent state. We conclude that posttranscriptional regulation of mRNAs plays a crucial role in the transition in and out of quiescence.
Collapse
Affiliation(s)
- Lihong Li
- Basic Science Division, Fred Hutchinson Cancer Research Center, Seattle, WA 98109
| | | | | | | | | | | |
Collapse
|
140
|
Vevea JD, Swayne TC, Boldogh IR, Pon LA. Inheritance of the fittest mitochondria in yeast. Trends Cell Biol 2013; 24:53-60. [PMID: 23932848 DOI: 10.1016/j.tcb.2013.07.003] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2013] [Revised: 07/02/2013] [Accepted: 07/08/2013] [Indexed: 01/01/2023]
Abstract
Eukaryotic cells compartmentalize their biochemical processes within organelles, which have specific functions that must be maintained for overall cellular health. As the site of aerobic energy mobilization and essential biosynthetic activities, mitochondria are critical for cell survival and proliferation. Here, we describe mechanisms to control the quality and quantity of mitochondria within cells with an emphasis on findings from the budding yeast Saccharomyces cerevisiae. We also describe how mitochondrial quality and quantity control systems that operate during cell division affect lifespan and cell cycle progression.
Collapse
Affiliation(s)
- Jason D Vevea
- Department of Pathology and Cell Biology, Columbia University, New York, NY, USA
| | - Theresa C Swayne
- Herbert Irving Comprehensive Cancer Center, Columbia University, New York, NY, USA
| | - Istvan R Boldogh
- Department of Pathology and Cell Biology, Columbia University, New York, NY, USA
| | - Liza A Pon
- Department of Pathology and Cell Biology, Columbia University, New York, NY, USA; Herbert Irving Comprehensive Cancer Center, Columbia University, New York, NY, USA.
| |
Collapse
|
141
|
Vevea JD, Alessi Wolken DM, Swayne TC, White AB, Pon LA. Ratiometric biosensors that measure mitochondrial redox state and ATP in living yeast cells. J Vis Exp 2013:50633. [PMID: 23912244 DOI: 10.3791/50633] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Abstract
Mitochondria have roles in many cellular processes, from energy metabolism and calcium homeostasis to control of cellular lifespan and programmed cell death. These processes affect and are affected by the redox status of and ATP production by mitochondria. Here, we describe the use of two ratiometric, genetically encoded biosensors that can detect mitochondrial redox state and ATP levels at subcellular resolution in living yeast cells. Mitochondrial redox state is measured using redox-sensitive Green Fluorescent Protein (roGFP) that is targeted to the mitochondrial matrix. Mito-roGFP contains cysteines at positions 147 and 204 of GFP, which undergo reversible and environment-dependent oxidation and reduction, which in turn alter the excitation spectrum of the protein. MitGO-ATeam is a Förster resonance energy transfer (FRET) probe in which the ε subunit of the FoF1-ATP synthase is sandwiched between FRET donor and acceptor fluorescent proteins. Binding of ATP to the ε subunit results in conformation changes in the protein that bring the FRET donor and acceptor in close proximity and allow for fluorescence resonance energy transfer from the donor to acceptor.
Collapse
Affiliation(s)
- Jason D Vevea
- Department of Pathology and Cell Biology, Columbia University
| | | | | | - Adam B White
- Herbert Irving Comprehensive Cancer Center, Columbia University
| | - Liza A Pon
- Department of Pathology and Cell Biology, Columbia University
| |
Collapse
|
142
|
Roles of mitochondrial dynamics under stressful and normal conditions in yeast cells. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2013; 2013:139491. [PMID: 23956814 PMCID: PMC3728513 DOI: 10.1155/2013/139491] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/07/2013] [Accepted: 06/25/2013] [Indexed: 01/20/2023]
Abstract
Eukaryotic cells contain dynamic mitochondrial filaments: they fuse and divide. Here we summarize data on the protein machinery driving mitochondrial dynamics in yeast and also discuss the factors that affect the fusion-fission balance. Fission is a general stress response of cells, and in the case of yeast this response appears to be prosurvival. At the same time, even under normal conditions yeast mitochondria undergo continuous cycles of fusion and fission. This seems to be a futile cycle and also expensive from the energy point of view. Why does it exist? Benefits might be the same as in the case of sexual reproduction. Indeed, mixing and separating of mitochondrial content allows mitochondrial DNA to segregate and recombine randomly, leading to high variation in the numbers of mutations per individual mitochondrion. This opens a possibility for effective purifying selection-elimination of mitochondria highly contaminated by deleterious mutations. The beneficial action presumes a mechanism for removal of defective mitochondria. We argue that selective mitochondrial autophagy or asymmetrical distribution of mitochondria during cell division could be at the core of such mechanism.
Collapse
|
143
|
Lewandowska A, Macfarlane J, Shaw JM. Mitochondrial association, protein phosphorylation, and degradation regulate the availability of the active Rab GTPase Ypt11 for mitochondrial inheritance. Mol Biol Cell 2013; 24:1185-95. [PMID: 23427260 PMCID: PMC3623639 DOI: 10.1091/mbc.e12-12-0848] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
There are conflicting models regarding the role of the Ypt11 GTPase in mitochondrial inheritance during yeast budding. This study demonstrates that Ypt11 function requires mitochondrial membrane targeting and GTPase domain–dependent effector interactions. In addition, the abundance of active Ypt11 forms is controlled by phosphorylation and degradation. The Rab GTPase Ypt11 is a Myo2-binding protein implicated in mother-to-bud transport of the cortical endoplasmic reticulum (ER), late Golgi, and mitochondria during yeast division. However, its reported subcellular localization does not reflect all of these functions. Here we show that Ypt11 is normally a low-abundance protein whose ER localization is only detected when the protein is highly overexpressed. Although it has been suggested that ER-localized Ypt11 and ER–mitochondrial contact sites might mediate passive transport of mitochondria into the bud, we found that mitochondrial, but not ER, association is essential for Ypt11 function in mitochondrial inheritance. Our studies also reveal that Ypt11 function is regulated at multiple levels. In addition to membrane targeting and GTPase domain–dependent effector interactions, the abundance of active Ypt11 forms is controlled by phosphorylation status and degradation. We present a model that synthesizes these new features of Ypt11 function and regulation in mitochondrial inheritance.
Collapse
Affiliation(s)
- Agnieszka Lewandowska
- Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, UT 84112, USA
| | | | | |
Collapse
|
144
|
Jazwinski SM. The retrograde response: when mitochondrial quality control is not enough. BIOCHIMICA ET BIOPHYSICA ACTA 2013. [PMID: 22374136 DOI: 10.1016/j.bbamcr.2012.02.010 [epub ahead of print]] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Mitochondria are responsible for generating adenosine triphosphate (ATP) and metabolic intermediates for biosynthesis. These dual functions require the activity of the electron transport chain in the mitochondrial inner membrane. The performance of these electron carriers is imperfect, resulting in release of damaging reactive oxygen species. Thus, continued mitochondrial activity requires maintenance. There are numerous means by which this quality control is ensured. Autophagy and selective mitophagy are among them. However, the cell inevitably must compensate for declining quality control by activating a variety of adaptations that entail the signaling of the presence of mitochondrial dysfunction to the nucleus. The best known of these is the retrograde response. This signaling pathway is triggered by the loss of mitochondrial membrane potential, which engages a series of signal transduction proteins, and it culminates in the induction of a broad array of nuclear target genes. One of the hallmarks of the retrograde response is its capacity to extend the replicative life span of the cell. The retrograde signaling pathway interacts with several other signaling pathways, such as target of rapamycin (TOR) and ceramide signaling. All of these pathways respond to stress, including metabolic stress. The retrograde response is also linked to both autophagy and mitophagy at the gene and protein activation levels. Another quality control mechanism involves age-asymmetry in the segregation of dysfunctional mitochondria. One of the processes that impinge on this age-asymmetry is related to biogenesis of the organelle. Altogether, it is apparent that mitochondrial quality control constitutes a complex network of processes, whose full understanding will require a systems approach. This article is part of a Special Issue entitled: Protein Import and Quality Control in Mitochondria and Plastids.
Collapse
Affiliation(s)
- S Michal Jazwinski
- Tulane Center for Aging and Department of Medicine, Tulane University Health Sciences Center, New Orleans, LA 70112, USA.
| |
Collapse
|
145
|
Delaney JR, Murakami C, Chou A, Carr D, Schleit J, Sutphin GL, An EH, Castanza AS, Fletcher M, Goswami S, Higgins S, Holmberg M, Hui J, Jelic M, Jeong KS, Kim JR, Klum S, Liao E, Lin MS, Lo W, Miller H, Moller R, Peng ZJ, Pollard T, Pradeep P, Pruett D, Rai D, Ros V, Schuster A, Singh M, Spector BL, Wende HV, Wang AM, Wasko BM, Olsen B, Kaeberlein M. Dietary restriction and mitochondrial function link replicative and chronological aging in Saccharomyces cerevisiae. Exp Gerontol 2012; 48:1006-13. [PMID: 23235143 DOI: 10.1016/j.exger.2012.12.001] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2012] [Revised: 11/27/2012] [Accepted: 12/03/2012] [Indexed: 12/30/2022]
Abstract
Chronological aging of budding yeast cells results in a reduction in subsequent replicative life span through unknown mechanisms. Here we show that dietary restriction during chronological aging delays the reduction in subsequent replicative life span up to at least 23days of chronological age. We further show that among the viable portion of the control population aged 26days, individual cells with the lowest mitochondrial membrane potential have the longest subsequent replicative lifespan. These observations demonstrate that dietary restriction modulates a common molecular mechanism linking chronological and replicative aging in yeast and indicate a critical role for mitochondrial function in this process.
Collapse
Affiliation(s)
- Joe R Delaney
- Department of Pathology, University of Washington, Seattle, WA 98195-7470, USA
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
146
|
Rafelski SM, Viana MP, Zhang Y, Chan YHM, Thorn KS, Yam P, Fung JC, Li H, Costa LDF, Marshall WF. Mitochondrial network size scaling in budding yeast. Science 2012; 338:822-4. [PMID: 23139336 DOI: 10.1126/science.1225720] [Citation(s) in RCA: 131] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Mitochondria must grow with the growing cell to ensure proper cellular physiology and inheritance upon division. We measured the physical size of mitochondrial networks in budding yeast and found that mitochondrial network size increased with increasing cell size and that this scaling relation occurred primarily in the bud. The mitochondria-to-cell size ratio continually decreased in aging mothers over successive generations. However, regardless of the mother's age or mitochondrial content, all buds attained the same average ratio. Thus, yeast populations achieve a stable scaling relation between mitochondrial content and cell size despite asymmetry in inheritance.
Collapse
Affiliation(s)
- Susanne M Rafelski
- Department of Biochemistry and Biophysics, University of California-San Francisco (UCSF), San Francisco, CA, USA.
| | | | | | | | | | | | | | | | | | | |
Collapse
|
147
|
An early age increase in vacuolar pH limits mitochondrial function and lifespan in yeast. Nature 2012; 492:261-5. [PMID: 23172144 PMCID: PMC3521838 DOI: 10.1038/nature11654] [Citation(s) in RCA: 392] [Impact Index Per Article: 32.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2011] [Accepted: 10/04/2012] [Indexed: 12/30/2022]
Abstract
Mitochondria have a central role in ageing. They are considered to be both a target of the ageing process and a contributor to it. Alterations in mitochondrial structure and function are evident during ageing in most eukaryotes, but how this occurs is poorly understood. Here we identify a functional link between the lysosome-like vacuole and mitochondria in Saccharomyces cerevisiae, and show that mitochondrial dysfunction in replicatively aged yeast arises from altered vacuolar pH. We found that vacuolar acidity declines during the early asymmetric divisions of a mother cell, and that preventing this decline suppresses mitochondrial dysfunction and extends lifespan. Surprisingly, changes in vacuolar pH do not limit mitochondrial function by disrupting vacuolar protein degradation, but rather by reducing pH-dependent amino acid storage in the vacuolar lumen. We also found that calorie restriction promotes lifespan extension at least in part by increasing vacuolar acidity via conserved nutrient-sensing pathways. Interestingly, although vacuolar acidity is reduced in aged mother cells, acidic vacuoles are regenerated in newborn daughters, coinciding with daughter cells having a renewed lifespan potential. Overall, our results identify vacuolar pH as a critical regulator of ageing and mitochondrial function, and outline a potentially conserved mechanism by which calorie restriction delays the ageing process. Because the functions of the vacuole are highly conserved throughout evolution, we propose that lysosomal pH may modulate mitochondrial function and lifespan in other eukaryotic cells.
Collapse
|
148
|
Quintana A, Hoth M. Mitochondrial dynamics and their impact on T cell function. Cell Calcium 2012; 52:57-63. [PMID: 22425631 DOI: 10.1016/j.ceca.2012.02.005] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2012] [Revised: 02/14/2012] [Accepted: 02/15/2012] [Indexed: 12/23/2022]
Abstract
Energy supply is the most prominent function of mitochondria, but in addition, mitochondria are indispensable for a multitude of other important cellular functions including calcium (Ca(2+)) signaling and buffering, the supply of metabolites and the sequestration of apoptotic factors. The efficiency of those functions highly depends on the proper positioning of mitochondria within the cytosol. In lymphocytes, mitochondria preferentially localize into the vicinity (∼200nm) of the immune synapse (IS). This localization is regulated by motor-based cytoskeleton-mediated transport, the fusion/fission dynamics of mitochondria, and probably also through tethering with the ER. IS formation also induces the accumulation of CRAC/ORAI1 Ca(2+) channels, the CRAC/ORAI channel activator STIM1, K(+) channels and plasma membrane Ca(2+) ATPase (PMCA) within the IS. Such a large agglomeration of Ca(2+) binding organelles and proteins highlights the IS as a critical cellular compartment for Ca(2+) dependent lymphocyte activation. At the IS, Ca(2+) microdomains generated beneath open CRAC/ORAI channels provide a rapid, robust and reliable mechanism for driving cellular responses in mast cells and T cells. Here, we discuss the relevance of motor-based mitochondrial transport, fusion, fission and tethering for mitochondrial localization in T cells and the importance of subplasmalemmal mitochondria to control local CRAC/ORAI1-dependent Ca(2+) microdomains at the IS for efficient T lymphocyte activation.
Collapse
Affiliation(s)
- Ariel Quintana
- La Jolla Institute for Allergy& Immunology, La Jolla, CA 92037, USA
| | | |
Collapse
|
149
|
Jazwinski SM. The retrograde response: when mitochondrial quality control is not enough. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2012; 1833:400-9. [PMID: 22374136 DOI: 10.1016/j.bbamcr.2012.02.010] [Citation(s) in RCA: 102] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/16/2012] [Revised: 02/10/2012] [Accepted: 02/12/2012] [Indexed: 12/28/2022]
Abstract
Mitochondria are responsible for generating adenosine triphosphate (ATP) and metabolic intermediates for biosynthesis. These dual functions require the activity of the electron transport chain in the mitochondrial inner membrane. The performance of these electron carriers is imperfect, resulting in release of damaging reactive oxygen species. Thus, continued mitochondrial activity requires maintenance. There are numerous means by which this quality control is ensured. Autophagy and selective mitophagy are among them. However, the cell inevitably must compensate for declining quality control by activating a variety of adaptations that entail the signaling of the presence of mitochondrial dysfunction to the nucleus. The best known of these is the retrograde response. This signaling pathway is triggered by the loss of mitochondrial membrane potential, which engages a series of signal transduction proteins, and it culminates in the induction of a broad array of nuclear target genes. One of the hallmarks of the retrograde response is its capacity to extend the replicative life span of the cell. The retrograde signaling pathway interacts with several other signaling pathways, such as target of rapamycin (TOR) and ceramide signaling. All of these pathways respond to stress, including metabolic stress. The retrograde response is also linked to both autophagy and mitophagy at the gene and protein activation levels. Another quality control mechanism involves age-asymmetry in the segregation of dysfunctional mitochondria. One of the processes that impinge on this age-asymmetry is related to biogenesis of the organelle. Altogether, it is apparent that mitochondrial quality control constitutes a complex network of processes, whose full understanding will require a systems approach. This article is part of a Special Issue entitled: Protein Import and Quality Control in Mitochondria and Plastids.
Collapse
Affiliation(s)
- S Michal Jazwinski
- Tulane Center for Aging and Department of Medicine, Tulane University Health Sciences Center, New Orleans, LA 70112, USA.
| |
Collapse
|
150
|
Swayne TC, Zhou C, Boldogh IR, Charalel JK, McFaline-Figueroa JR, Thoms S, Yang C, Leung G, McInnes J, Erdmann R, Pon LA. Role for cER and Mmr1p in anchorage of mitochondria at sites of polarized surface growth in budding yeast. Curr Biol 2011; 21:1994-9. [PMID: 22119524 DOI: 10.1016/j.cub.2011.10.019] [Citation(s) in RCA: 85] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2010] [Revised: 09/16/2011] [Accepted: 10/11/2011] [Indexed: 12/21/2022]
Abstract
Mitochondria accumulate at neuronal and immunological synapses and yeast bud tips and associate with the ER during phospholipid biosynthesis, calcium homeostasis, and mitochondrial fission. Here we show that mitochondria are associated with cortical ER (cER) sheets underlying the plasma membrane in the bud tip and confirm that a deletion in YPT11, which inhibits cER accumulation in the bud tip, also inhibits bud tip anchorage of mitochondria. Time-lapse imaging reveals that mitochondria are anchored at specific sites in the bud tip. Mmr1p, a member of the DSL1 family of tethering proteins, localizes to punctate structures on opposing surfaces of mitochondria and cER sheets underlying the bud tip and is recovered with isolated mitochondria and ER. Deletion of MMR1 impairs bud tip anchorage of mitochondria without affecting mitochondrial velocity or cER distribution. Deletion of the phosphatase PTC1 results in increased Mmr1p phosphorylation, mislocalization of Mmr1p, defects in association of Mmr1p with mitochondria and ER, and defects in bud tip anchorage of mitochondria. These findings indicate that Mmr1p contributes to mitochondrial inheritance as a mediator of anchorage of mitochondria to cER sheets in the yeast bud tip and that Ptc1p regulates Mmr1p phosphorylation, localization, and function.
Collapse
Affiliation(s)
- Theresa C Swayne
- Department of Pathology and Cell Biology, Columbia University College of Physicians and Surgeons, New York, NY 10032, USA
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|