| 1. |
- Ahmadpour, Doryaneh, 1973, et al.
(författare)
-
Syntaxin 5-dependent phosphorylation of the small heat shock protein Hsp42 and its role in protein quality control
- 2023
-
Ingår i: Febs Journal. - 1742-464X. ; 290:19, s. 4744-4761
-
Tidskriftsartikel (refereegranskat)abstract
- The small heat shock protein Hsp42 and the t-SNARE protein Sed5 have central roles in the sequestration of misfolded proteins into insoluble protein deposits in the yeast Saccharomyces cerevisiae. However, whether these proteins/processes interact in protein quality control (PQC) is not known. Here, we show that Sed5 and anterograde trafficking modulate phosphorylation of Hsp42 partially via the MAPK kinase Hog1. Such phosphorylation, specifically at residue S215, abrogated the co-localization of Hsp42 with the Hsp104 disaggregase, aggregate clearance, chaperone activity, and sequestration of aggregates to IPOD and mitochondria. Furthermore, we found that Hsp42 is hyperphosphorylated in old cells leading to a drastic failure in disaggregation. Old cells also displayed a retarded anterograde trafficking, which, together with slow aggregate clearance and hyperphosphorylation of Hsp42, could be counteracted by Sed5 overproduction. We hypothesize that the breakdown of proper PQC during yeast aging may, in part, be due to a retarded anterograde trafficking leading to hyperphosphorylation of Hsp42.
|
|
| 2. |
- Babazadeh, Roja, et al.
(författare)
-
Syntaxin 5 Is Required for the Formation and Clearance of Protein Inclusions during Proteostatic Stress
- 2019
-
Ingår i: Cell Reports. - : Elsevier BV. - 2211-1247. ; 28:8
-
Tidskriftsartikel (refereegranskat)abstract
- Spatial sorting to discrete quality control sites in the cell is a process harnessing the toxicity of aberrant proteins. We show that the yeast t-snare phosphoprotein syntaxin5 (Sed5) acts as a key factor in mitigating proteotoxicity and the spatial deposition and clearance of IPOD (insoluble protein deposit) inclusions associates with the disaggregase Hsp104. Sed5 phosphorylation promotes dynamic movement of COPII-associated Hsp104 and boosts disaggregation by favoring anterograde ER-to-Golgi trafficking. Hsp104-associated aggregates co-localize with Sed5 as well as components of the ER, trans Golgi network, and endocytic vesicles, transiently during proteostatic stress, explaining mechanistically how misfolded and aggregated proteins formed at the vicinity of the ER can hitchhike toward vacuolar IPOD sites. Many inclusions become associated with mitochondria in a HOPS/vCLAMP-dependent manner and co-localize with Vps39 (HOPS/vCLAMP) and Vps13, which are proteins providing contacts between vacuole and mitochondria. Both Vps39 and Vps13 are required also for efficient Sed5-dependent clearance of aggregates.
|
|
| 3. |
- Cvjetkovic, Aleksander, et al.
(författare)
-
Extracellular vesicles in motion
- 2017
-
Ingår i: Science Matters. - : Sciencematters. - 2297-8240 .- 2297-9239.
-
Tidskriftsartikel (refereegranskat)abstract
- By secreting extracellular vesicles (EVs), including exosomes and microvesicles, into the extracellular milieu, cells can convey complex biological messages between each other. These vesicles are generally thought to be static packages lacking the flexibility of their parental cells in terms of motility and the ability to change shape. However, cryo-electron micrographs reveal the presence of actin-like filaments in a subpopulation of EVs, raising the question if these vesicles could possess motile capabilities similar to that produced by actin in cells. We here show that fluorescently labeled EVs change their shape in a matter of minutes, regardless of whether they are isolated from human body fluids, mouse tissue or cell culture of human cells or yeast. Our findings therefore cast doubt on movement being confined to cells, suggesting that some EVs indeed have an intrinsic capacity to move. This novel observation showing morphological plasticity among EVs adds another level of complexity to the already multifaceted vesicular secretome, and may lead to new ways in which we perceive these nano-carriers of intercellular signals.
|
|
| 4. |
- Hill, Sandra Malmgren, 1987, et al.
(författare)
-
Asymmetric Inheritance of Aggregated Proteins and Age Reset in Yeast Are Regulated by Vac17-Dependent Vacuolar Functions
- 2016
-
Ingår i: Cell Reports. - : Elsevier BV. - 2211-1247. ; 16:3, s. 826-838
-
Tidskriftsartikel (refereegranskat)abstract
- Age can be reset during mitosis in both yeast and stem cells to generate a young daughter cell from an aged and deteriorated one. This phenomenon requires asymmetry-generating genes (AGGs) that govern the asymmetrical inheritance of aggregated proteins. Using a genome-wide imaging screen to identify AGGs in Saccharomyces cerevisiae, we discovered a previously unknown role for endocytosis, vacuole fusion, and the myosin-dependent adaptor protein Vac17 in asymmetrical inheritance of misfolded proteins. Overproduction of Vac17 increases deposition of aggregates into cytoprotective vacuole-associated sites, counteracts age-related breakdown of endocytosis and vacuole integrity, and extends replicative lifespan. The link between damage asymmetry and vesicle trafficking can be explained by a direct interaction between aggregates and vesicles. We also show that the protein disaggregase Hsp104 interacts physically with endocytic vesicle-associated proteins, such as the dynamin-like protein, Vps1, which was also shown to be required for Vac17-dependent sequestration of protein aggregates. These data demonstrate that two physiognomies of aging-reduced endocytosis and protein aggregation-are interconnected and regulated by Vac17.
|
|
| 5. |
- Keuenhof, Katharina, 1994, et al.
(författare)
-
Large organellar changes occur during mild heat shock in yeast
- 2021
-
Ingår i: Journal of cell science. - : The Company of Biologists. - 1477-9137 .- 0021-9533. ; 135:5
-
Tidskriftsartikel (refereegranskat)abstract
- When the temperature is increased, the heat shock response is activated to protect the cellular environment. The transcriptomics and proteomics of this process are intensively studied, while information about how the cell responds structurally to heat stress is mostly lacking. Here, Saccharomyces cerevisiae were subjected to a mild continuous heat shock (38°C) and intermittently cryo-immobilized for electron microscopy. Through measuring changes in all distinguishable organelle numbers, sizes, and morphologies in over 2100 electron micrographs a major restructuring of the cell's internal architecture during the progressive heat shock was revealed. The cell grew larger but most organelles within it expanded even more, shrinking the volume of the cytoplasm. Organelles responded to heat shock at different times, both in terms of size and number, and adaptations of certain organelles' morphology (such as the vacuole), were observed. Multivesicular bodies grew to almost 170% in size, indicating a previously unknown involvement in the heat shock response. A previously undescribed electron translucent structure accumulated close to the plasma membrane. This all-encompassing approach provides a detailed chronological progression of organelle adaptation throughout the cellular heat-stress response.
|
|
| 6. |
- Niklasson, Bo, et al.
(författare)
-
Development of type 1 diabetes in wild bank voles associated with islet autoantibodies and the novel ljungan virus.
- 2003
-
Ingår i: International journal of experimental diabesity research. - : Hindawi Limited. ; 4:1, s. 35-44
-
Tidskriftsartikel (refereegranskat)abstract
- Wild bank voles (Clethrionomys glareolus) may develop diabetes in laboratory captivity. The aim of this study was to test whether bank voles develop type 1 diabetes in association with Ljungan virus. Two groups of bank voles were analyzed for diabetes, pancreas histology, autoantibodies to glutamic acid decarboxylase (GAD65), IA-2, and insulin by standardized radioligand-binding assays as well as antibodies to in vitro transcribed and translated Ljungan virus antigens. Group A represented 101 trapped bank voles, which were screened for diabetes when euthanized within 24 hours of capture. Group B represented 67 bank voles, which were trapped and kept in the laboratory for 1 month before being euthanized. Group A bank voles did not have diabetes. Bank voles in group B (22/67; 33%) developed diabetes due to specific lysis of pancreatic islet beta cells. Compared to nondiabetic group B bank voles, diabetic animals had increased levels of GAD65 (P < .0001), IA-2 (P < .0001), and insulin (P
|
|
| 7. |
- Rondelet, A., et al.
(författare)
-
Clathrin's adaptor interaction sites are repurposed to stabilize microtubules during mitosis
- 2020
-
Ingår i: Journal of Cell Biology. - : Rockefeller University Press. - 0021-9525 .- 1540-8140. ; 219:2
-
Tidskriftsartikel (refereegranskat)abstract
- Clathrin ensures mitotic spindle stability and efficient chromosome alignment, independently of its vesicle trafficking function. Although clathrin localizes to the mitotic spindle and kinetochore fiber microtubule bundles, the mechanisms by which clathrin stabilizes microtubules are unclear. We show that clathrin adaptor interaction sites on clathrin heavy chain (CHC) are repurposed during mitosis to directly recruit the microtubule-stabilizing protein GTSE1 to the spindle. Structural analyses reveal that these sites interact directly with clathrin-box motifs on GTSE1. Disruption of this interaction releases GTSE1 from spindles, causing defects in chromosome alignment. Surprisingly, this disruption destabilizes astral microtubules, but not kinetochore-microtubule attachments, and chromosome alignment defects are due to a failure of chromosome congression independent of kinetochore-microtubule attachment stability. GTSE1 recruited to the spindle by clathrin stabilizes microtubules by inhibiting the microtubule depolymerase MCAK. This work uncovers a novel role of clathrin adaptor-type interactions to stabilize nonkinetochore fiber microtubules to support chromosome congression, defining for the first time a repurposing of this endocytic interaction mechanism during mitosis.
|
|
| 8. |
- Schneider, Kara, et al.
(författare)
-
Elimination of virus-like particles reduces protein aggregation and extends replicative lifespan in Saccharomyces cerevisiae
- 2024
-
Ingår i: Proceedings of the National Academy of Science of the United States of America. - 0027-8424 .- 1091-6490. ; 121:14
-
Tidskriftsartikel (refereegranskat)abstract
- A major consequence of aging and stress, in yeast to humans, is an increased accumulation of protein aggregates at distinct sites within the cells. Using genetic screens, immunoelectron microscopy, and three-dimensional modeling in our efforts to elucidate the importance of aggregate annexation, we found that most aggregates in yeast accumulate near the surface of mitochondria. Further, we show that virus-like particles (VLPs), which are part of the retrotransposition cycle of Ty elements, are markedly enriched in these sites of protein aggregation. RNA interference-mediated silencing of Ty expression perturbed aggregate sequestration to mitochondria, reduced overall protein aggregation, mitigated toxicity of a Huntington's disease model, and expanded the replicative lifespan of yeast in a partially Hsp104-dependent manner. The results are in line with recent data demonstrating that VLPs might act as aging factors in mammals, including humans, and extend these findings by linking VLPs to a toxic accumulation of protein aggregates and raising the possibility that they might negatively influence neurological disease progression.
|
|
| 9. |
- Schneider, Kara, et al.
(författare)
-
Studying Spatial Protein Quality Control, Proteopathies, and Aging Using Different Model Misfolding Proteins in S. cerevisiae
- 2018
-
Ingår i: Frontiers in Molecular Neuroscience. - : Frontiers Media SA. - 1662-5099. ; 11
-
Tidskriftsartikel (refereegranskat)abstract
- Protein quality control (PQC) is critical to maintain a functioning proteome. Misfolded or toxic proteins are either refolded or degraded by a system of temporal quality control and can also be sequestered into aggregates or inclusions by a system of spatial quality control. Breakdown of this concerted PQC network with age leads to an increased risk for the onset of disease, particularly neurological disease. Saccharomyces cerevisiae has been used extensively to elucidate PQC pathways and general evolutionary conservation of the PQC machinery has led to the development of several useful S. cerevisiae models of human neurological diseases. Key to both of these types of studies has been the development of several different model misfolding proteins, which are used to challenge and monitor the PQC machinery. In this review, we summarize and compare the model misfolding proteins that have been used to specifically study spatial PQC in S. cerevisiae, as well as the misfolding proteins that have been shown to be subject to spatial quality control in S. cerevisiae models of human neurological diseases.
|
|
| 10. |
- Schneider, Kara, et al.
(författare)
-
Using reporters of different misfolded proteins reveals differential strategies in processing protein aggregates
- 2022
-
Ingår i: Journal of Biological Chemistry. - : Elsevier BV. - 0021-9258 .- 1083-351X. ; 298:11
-
Tidskriftsartikel (refereegranskat)abstract
- The accumulation of misfolded proteins is a hallmark of aging and many neurodegenerative diseases, making it important to understand how the cellular machinery recognizes and processes such proteins. A key question in this respect is whether misfolded proteins are handled in a similar way regardless of their genetic origin. To approach this question, we compared how three different misfolded proteins, guk1-7, gus1-3, and pro3-1, are handled by the cell. We show that all three are nontoxic, even though highly overexpressed, highlighting their usefulness in analyzing the cellular response to misfolding in the absence of severe stress. We found significant differences between the aggregation and disaggregation behavior of the misfolded proteins. Specifically, gus1-3 formed some aggregates that did not efficiently recruit the protein disaggregase Hsp104 and did not colocalize with the other misfolded reporter proteins. Strikingly, while all three misfolded proteins generally coaggregated and colocalized to specific sites in the cell, disaggregation was notably different; the rate of aggregate clearance of pro3-1 was faster than that of the other misfolded proteins, and its clearance rate was not hindered when pro3-1 colocalized with a slowly resolved misfolded protein. Finally, we observed using super-resolution light microscopy as well as immunogold labeling EM in which both showed an even distribution of the different misfolded proteins within an inclusion, suggesting that misfolding characteristics and remodeling, rather than spatial compartmentalization, allows for differential clearance of these misfolding reporters residing in the same inclusion. Taken together, our results highlight how properties of misfolded proteins can significantly affect processing.
|
|
