| 1. |
- Eriksson, Emma, 1980, et al.
(författare)
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A microfluidic system in combination with optical tweezers for analyzing rapid and reversible cytological alterations in single cells upon environmental changes
- 2007
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Ingår i: Lab on a chip. - : Royal Society of Chemistry (RSC). - 1473-0197 .- 1473-0189. ; 7:1, s. 71-76
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Tidskriftsartikel (refereegranskat)abstract
- We report on the development of an experimental platform where epi-fluorescence microscopy and optical tweezers are combined with a microfluidic system to enable the analysis of rapid cytological responses in single cells. The microfluidic system allows two different media to be merged in a Y-shaped channel. Microscale channel dimensions ensure purely laminar flow and, as a result, an environmental gradient can be created between the two media. Optical tweezers are used to move a single trapped cell repeatedly between the different environments. The cell is monitored continuously by fluorescence microscopy during the experiment. In a first experiment on yeast (Saccharomyces cerevisiae) we observed changes in cell volume as the cell was moved between environments with different osmolarity. This demonstrated that the platform allowed analysis of cytological alterations on a time scale shorter than 0.2 s. In a second experiment we observed the spatial migration of the Yap1p transcription factor fused to GFP as a cell was moved from an environment of low to high oxidative capacity. The system is universal allowing the response to numerous environmental changes to be studied on the sub second time scale in a variety of model cells. We intend to use the platform to study how the age of cells, their progression through the cell cycle, or their genetic landscape, alter their capacity (kinetics and amplitude) to respond to environmental changes.
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| 2. |
- Fredriksson, Åsa, 1968, et al.
(författare)
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Decline in ribosomal fidelity contributes to the accumulation and stabilization of the master stress response regulator sigma S upon carbon starvation
- 2007
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Ingår i: Genes & Development. - : Cold Spring Harbor Laboratory. - 0890-9369 .- 1549-5477. ; 21:7, s. 862-874
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Tidskriftsartikel (refereegranskat)abstract
- The {sigma}S subunit of RNA polymerase is a master regulator of Escherichia coli that retards cellular senescence and bestows cells with general stress protective functions during growth arrest. We show that mutations and drugs triggering translational errors elevate {sigma}S levels and stability. Furthermore, mutations enhancing translational fidelity attenuate induction of the rpoS regulon and prevent stabilization of {sigma}S upon carbon starvation. Destabilization of {sigma}S by increased proofreading requires the presence of the {sigma}S recognition factor SprE (RssB) and the ClpXP protease. The data further suggest that {sigma}S becomes stabilized upon starvation as a result of ClpP sequestration and this sequestration is enhanced by oxidative modifications of aberrant proteins produced by erroneous translation. ClpP overproduction counteracted starvation-induced stabilization of {sigma}S, whereas overproduction of a ClpXP substrate (ssrA-tagged GFP) stabilized {sigma}S in exponentially growing cells. We present a model for the sequence of events leading to the accumulation and activation of {sigma}S upon carbon starvation, which are linked to alterations in both ribosomal fidelity and efficiency.
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| 3. |
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| 4. |
- Langegård, Ulrica, 1969, et al.
(författare)
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The Art of Living With Symptoms : A Qualitative Study Among Patients With Primary Brain Tumors Receiving Proton Beam Therapy
- 2020
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Ingår i: Cancer Nursing. - Philadelphia : LIPPINCOTT WILLIAMS & WILKINS. - 0162-220X .- 1538-9804. ; 43:2, s. E79-E86
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Tidskriftsartikel (refereegranskat)abstract
- Background: Symptom management in conjunction with proton beam therapy (PBT) from patient's perspective has not been explored. Such knowledge is essential to optimize the care in this relatively new treatment modality.Objective: The aim of this study was to explore the process of symptom management in patients with brain tumor receiving PBT.Methods: Participants were 22 patients with primary brain tumor who received PBT, recruited in collaboration with a national center for proton therapy and 2 oncology clinics at 2 university hospitals in Sweden. Interviews using open-ended questions were conducted before, during, and/or after treatment. Verbatim interview transcripts were analyzed using classic Grounded Theory.Results: "The art of living with symptoms" emerged as the core concept. This encompassed 3 interconnected symptom management concepts: "Adapting to limited ability," "Learning about oneself," and "Creating new routines." These concepts were summarized in a substantive theoretical model of symptom management. Despite the struggle to manage symptoms, participants lived a satisfactory life.Conclusions: Symptom management in conjunction with PBT comprises a process of action, thoughts, and emotions. The concepts that emerged indicated patients' symptom management strategies were based on their own resources.Implications for Practice: It is important that PBT facilities develop an approach that facilitates the symptom management process based on patients' experiences of symptoms, as well as their actions and available resources.
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| 5. |
- Aertsen, A., et al.
(författare)
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Heat shock protein-mediated resistance to high hydrostatic pressure in Escherichia coli
- 2004
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Ingår i: Applied and Environmental Microbiology. - 0099-2240. ; 70:5, s. 2660-2666
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Tidskriftsartikel (refereegranskat)abstract
- A random library of Escherichia coli MG1655 genomic fragments fused to a promoterless green fluorescent protein (GFP) gene was constructed and screened by differential fluorescence induction for promoters that are induced after exposure to a sublethal high hydrostatic pressure stress. This screening yielded three promoters of genes belonging to the heat shock regulon (dnaK, lon, clpPX), suggesting a role for heat shock proteins in protection against, and/or repair of, damage caused by high pressure. Several further observations provide additional support for this hypothesis: (i) the expression of rpoH, encoding the heat shock-specific sigma factor {sigma}32, was also induced by high pressure; (ii) heat shock rendered E. coli significantly more resistant to subsequent high-pressure inactivation, and this heat shock-induced pressure resistance followed the same time course as the induction of heat shock genes; (iii) basal expression levels of GFP from heat shock promoters, and expression of several heat shock proteins as determined by two-dimensional sodium dodecyl sulfate-polyacrylamide gel electrophoresis of proteins extracted from pulse-labeled cells, was increased in three previously isolated pressure-resistant mutants of E. coli compared to wild-type levels.
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| 6. |
- Ahmadpour, Doryaneh, 1973, et al.
(författare)
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Hitchhiking on vesicles: a way to harness age-related proteopathies?
- 2020
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Ingår i: FEBS Journal. - : Wiley. - 1742-464X .- 1742-4658. ; 287:23, s. 5068-5079
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Tidskriftsartikel (refereegranskat)abstract
- Central to proteopathies and leading to most age-related neurodegenerative disorders is a failure in protein quality control (PQC). To harness the toxicity of misfolded and damaged disease proteins, such proteins are either refolded, degraded by temporal PQC, or sequestered by spatial PQC into specific, organelle-associated, compartments within the cell. Here, we discuss the impact of vesicle trafficking pathways in general, and syntaxin 5 in particular, as key players in spatial PQC directing misfolded proteins to the surface of vacuole and mitochondria, which facilitates their clearance and detoxification. Since boosting vesicle trafficking genetically can positively impact on spatial PQC and make cells less sensitive to misfolded disease proteins, we speculate that regulators of such trafficking might serve as therapeutic targets for age-related neurological disorders.
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| 7. |
- Andersson, Rebecca, et al.
(författare)
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Differential role of cytosolic Hsp70s in longevity assurance and protein quality control
- 2021
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Ingår i: PLoS Genetics. - : Public Library of Science (PLoS). - 1553-7404 .- 1553-7390. ; 17:1
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Tidskriftsartikel (refereegranskat)abstract
- 70 kDa heat shock proteins (Hsp70) are essential chaperones of the protein quality control network; vital for cellular fitness and longevity. The four cytosolic Hsp70's in yeast, Ssa1-4, are thought to be functionally redundant but the absence of Ssa1 and Ssa2 causes a severe reduction in cellular reproduction and accelerates replicative aging. In our efforts to identify which Hsp70 activities are most important for longevity assurance, we systematically investigated the capacity of Ssa4 to carry out the different activities performed by Ssa1/2 by overproducing Ssa4 in cells lacking these Hsp70 chaperones. We found that Ssa4, when overproduced in cells lacking Ssa1/2, rescued growth, mitigated aggregate formation, restored spatial deposition of aggregates into protein inclusions, and promoted protein degradation. In contrast, Ssa4 overproduction in the Hsp70 deficient cells failed to restore the recruitment of the disaggregase Hsp104 to misfolded/aggregated proteins, to fully restore clearance of protein aggregates, and to bring back the formation of the nucleolus-associated aggregation compartment. Exchanging the nucleotide-binding domain of Ssa4 with that of Ssa1 suppressed this 'defect' of Ssa4. Interestingly, Ssa4 overproduction extended the short lifespan of ssa1 Delta ssa2 Delta mutant cells to a lifespan comparable to, or even longer than, wild type cells, demonstrating that Hsp104-dependent aggregate clearance is not a prerequisite for longevity assurance in yeast. Author summary All organisms have proteins that network together to stabilize and protect the cell throughout its lifetime. One of these types of proteins are the Hsp70s (heat shock protein 70). Hsp70 proteins take part in folding other proteins to their functional form, untangling proteins from aggregates, organize aggregates inside the cell and ensure that damaged proteins are destroyed. In this study, we investigated three closely related Hsp70 proteins in yeast; Ssa1, 2 and 4, in an effort to describe the functional difference of Ssa4 compared to Ssa1 and 2 and to answer the question: What types of cellular stress protection are necessary to reach a normal lifespan? We show that Ssa4 can perform many of the same tasks as Ssa1 and 2, but Ssa4 doesn't interact in the same manner as Ssa1 and 2 with other types of proteins. This leads to a delay in removing protein aggregates created after heat stress. Ssa4 also cannot ensure that misfolded proteins aggregate correctly inside the nucleus of the cell. However, this turns out not to be necessary for yeast cells to achieve a full lifespan, which shows us that as long as cells can prevent aggregates from forming in the first place, they can reach a full lifespan.
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| 8. |
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| 9. |
- Andersson, Stefanie, 1989, et al.
(författare)
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Genome-wide imaging screen uncovers molecular determinants of arsenite-induced protein aggregation and toxicity
- 2021
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Ingår i: Journal of Cell Science. - : The Company of Biologists. - 0021-9533 .- 1477-9137. ; 134:11
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Tidskriftsartikel (refereegranskat)abstract
- The toxic metalloid arsenic causes widespread misfolding and aggregation of cellular proteins. How these protein aggregates are formed in vivo, the mechanisms by which they affect cells and how cells prevent their accumulation is not fully understood. To find components involved in these processes, we performed a genome-wide imaging screen and identified Saccharomyces cerevisiae deletion mutants with either enhanced or reduced protein aggregation levels during arsenite exposure. We show that many of the identified factors are crucial to safeguard protein homeostasis (proteostasis) and to protect cells against arsenite toxicity. The hits were enriched for various functions including protein biosynthesis and transcription, and dedicated follow-up experiments highlight the importance of accurate transcriptional and translational control for mitigating protein aggregation and toxicity during arsenite stress. Some of the hits are associated with pathological conditions, suggesting that arsenite-induced protein aggregation may affect disease processes. The broad network of cellular systems that impinge on proteostasis during arsenic stress identified in this current study provides a valuable resource and a framework for further elucidation of the mechanistic details of metalloid toxicity and pathogenesis. This article has an associated First Person interview with the first authors of the paper.
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| 10. |
- Andersson, Veronica, 1979, et al.
(författare)
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Enhancing protein disaggregation restores proteasome activity in aged cells
- 2013
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Ingår i: Aging-Us. - 1945-4589. ; 5:11, s. 802-812
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Tidskriftsartikel (refereegranskat)abstract
- The activity of the ubiquitin-proteasome system, UPS, declines during aging in several multicellular organisms. The reason behind this decline remains elusive. Here, using yeast as a model system, we show that while the level and potential capacity of the 26S proteasome is maintained in replicatively aged cells, the UPS is not functioning properly in vivo. As a consequence cytosolic UPS substrates, such as Delta ssCPY* are stabilized, accumulate, and form inclusions. By integrating a pGPD-HSP104 recombinant gene into the genome, we were able to constitutively elevate protein disaggregase activity, which diminished the accumulation of protein inclusions during aging. Remarkably, this elevated disaggregation restored degradation of a 26S proteasome substrate in aged cells without elevating proteasome levels, demonstrating that age-associated aggregation obstructs UPS function. The data supports the existence of a negative feedback loop that accelerates aging by exacerbating proteostatic decline once misfolded and aggregation-prone proteins reach a critical level.
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