| 1. |
|
|
| 2. |
- Aftab, Obaid, 1984-, et al.
(författare)
-
Label-free detection and dynamic monitoring of drug-induced intracellular vesicle formation enabled using a 2-dimensional matched filter
- 2014
-
Ingår i: Autophagy. - : Informa UK Limited. - 1554-8627 .- 1554-8635. ; 10:1, s. 57-69
-
Tidskriftsartikel (refereegranskat)abstract
- Analysis of vesicle formation and degradation is a central issue in autophagy research and microscopy imaging is revolutionizing the study of such dynamic events inside living cells. A limiting factor is the need for labeling techniques that are labor intensive, expensive, and not always completely reliable. To enable label-free analyses we introduced a generic computational algorithm, the label-free vesicle detector (LFVD), which relies on a matched filter designed to identify circular vesicles within cells using only phase-contrast microscopy images. First, the usefulness of the LFVD is illustrated by presenting successful detections of autophagy modulating drugs found by analyzing the human colorectal carcinoma cell line HCT116 exposed to each substance among 1266 pharmacologically active compounds. Some top hits were characterized with respect to their activity as autophagy modulators using independent in vitro labeling of acidic organelles, detection of LC3-II protein, and analysis of the autophagic flux. Selected detection results for 2 additional cell lines (DLD1 and RKO) demonstrate the generality of the method. In a second experiment, label-free monitoring of dose-dependent vesicle formation kinetics is demonstrated by recorded detection of vesicles over time at different drug concentrations. In conclusion, label-free detection and dynamic monitoring of vesicle formation during autophagy is enabled using the LFVD approach introduced.
|
|
| 3. |
- Brnjic, Slavica, et al.
(författare)
-
Induction of Tumor Cell Apoptosis by a Proteasome Deubiquitinase Inhibitor Is Associated with Oxidative Stress
- 2014
-
Ingår i: Antioxidants and Redox Signaling. - : Mary Ann Liebert Inc. - 1523-0864 .- 1557-7716. ; 21:17, s. 2271-2285
-
Tidskriftsartikel (refereegranskat)abstract
- Aims: b-AP15 is a recently described inhibitor of the USP14/UCHL5 deubiquitinases (DUBs) of the 19S proteasome. Exposure to b-AP15 results in blocking of proteasome function and accumulation of polyubiquitinated protein substrates in cells. This novel mechanism of proteasome inhibition may potentially be exploited for cancer therapy, in particular for treatment of malignancies resistant to currently used proteasome inhibitors. The aim of the present study was to characterize the cellular response to b-AP15-mediated proteasome DUB inhibition. Results: We report that b-AP15 elicits a similar, but yet distinct, cellular response as the clinically used proteasome inhibitor bortezomib. b-AP15 induces a rapid apoptotic response, associated with enhanced induction of oxidative stress and rapid activation of Jun-N-terminal kinase 1/2 (JNK)/activating protein-1 signaling. Scavenging of reactive oxygen species and pharmacological inhibition of JNK reduced b-AP15-induced apoptosis. We further report that endoplasmic reticulum (ER) stress is induced by b-AP15 and is involved in apoptosis induction. In contrast to bortezomib, ER stress is associated with induction of alpha-subunit of eukaryotic initiation factor 2 phosphorylation. Innovation: The findings establish that different modes of proteasome inhibition result in distinct cellular responses, a finding of potential therapeutic importance. Conclusion: Our data show that enhanced oxidative stress and ER stress are major determinants of the strong apoptotic response elicited by the 19S DUB inhibitor b-AP15. Antioxid. Redox Signal. 21, 2271-2285.
|
|
| 4. |
- Chen, Jialin, et al.
(författare)
-
Characterization and comparison of post-natal rat Achilles tendon-derived stem cells at different development stages
- 2016
-
Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 6
-
Tidskriftsartikel (refereegranskat)abstract
- Tendon stem/progenitor cells (TSPCs) are a potential cell source for tendon tissue engineering. The striking morphological and structural changes of tendon tissue during development indicate the complexity of TSPCs at different stages. This study aims to characterize and compare post-natal rat Achilles tendon tissue and TSPCs at different stages of development. The tendon tissue showed distinct differences during development: the tissue structure became denser and more regular, the nuclei became spindle-shaped and the cell number decreased with time. TSPCs derived from 7 day Achilles tendon tissue showed the highest self-renewal ability, cell proliferation, and differentiation potential towards mesenchymal lineage, compared to TSPCs derived from 1 day and 56 day tissue. Microarray data showed up-regulation of several groups of genes in TSPCs derived from 7 day Achilles tendon tissue, which may account for the unique cell characteristics during this specific stage of development. Our results indicate that TSPCs derived from 7 day Achilles tendon tissue is a superior cell source as compared to TSPCs derived from 1 day and 56 day tissue, demonstrating the importance of choosing a suitable stem cell source for effective tendon tissue engineering and regeneration.
|
|
| 5. |
- Fryknäs, Mårten, et al.
(författare)
-
Iron chelators target both proliferating and quiescent cancer cells
- 2016
-
Ingår i: Scientific Reports. - : NATURE PUBLISHING GROUP. - 2045-2322. ; 6
-
Tidskriftsartikel (refereegranskat)abstract
- Poorly vascularized areas of solid tumors contain quiescent cell populations that are resistant to cell cycle-active cancer drugs. The compound VLX600 was recently identified to target quiescent tumor cells and to inhibit mitochondrial respiration. We here performed gene expression analysis in order to characterize the cellular response to VLX600. The compound-specific signature of VLX600 revealed a striking similarity to signatures generated by compounds known to chelate iron. Validation experiments including addition of ferrous and ferric iron in excess, EXAFS measurements, and structure activity relationship analyses showed that VLX600 chelates iron and supported the hypothesis that the biological effects of this compound is due to iron chelation. Compounds that chelate iron possess anti-cancer activity, an effect largely attributed to inhibition of ribonucleotide reductase in proliferating cells. Here we show that iron chelators decrease mitochondrial energy production, an effect poorly tolerated by metabolically stressed tumor cells. These pleiotropic features make iron chelators an attractive option for the treatment of solid tumors containing heterogeneous populations of proliferating and quiescent cells.
|
|
| 6. |
- Habicht, Juri, et al.
(författare)
-
UNC-45A Breaks MT Lattice Independent of its Effect on Non-Muscle Myosin II
- 2020
-
Ingår i: Journal of Cell Science. - : The Company of Biologists. - 0021-9533 .- 1477-9137.
-
Tidskriftsartikel (refereegranskat)abstract
- In invertebrates, UNC-45 regulates myosin stability and functions. Vertebrates have two distinct isoforms of the protein: UNC-45B, expressed in muscle cells only and UNC-45A, expressed in all cells and implicated in regulating both Non-Muscle Myosin II (NMII)- and microtubule (MT)-associated functions. Here we show that both, in vitro and in cells, UNC-45A binds to the MT lattice leading to MT bending, breakage and depolymerization. Furthermore, we show that UNC-45A destabilizes MTs independent of its NMII C-terminal binding domain and even in presence of the NMII inhibitor blebbistatin. These findings identified UNC-45A as a novel type of MT-severing protein with a not mutually exclusive but rather dual role in regulating NMII activity and MT stability. Because many human diseases, from cancer to neurodegenerative diseases, are caused by or associated with deregulation of MT stability our findings have profound implications in both, the biology of MTs as well as the biology of human diseases and possible therapeutic implications for their treatment.
|
|
| 7. |
- Hernlund, Emma, et al.
(författare)
-
The phosphoinositide 3-kinase/mammalian target of rapamycin inhibitor NVP-BEZ235 is effective in inhibiting regrowth of tumour cells after cytotoxic therapy
- 2012
-
Ingår i: European Journal of Cancer. - : Elsevier BV. - 0959-8049 .- 1879-0852. ; 48:3, s. 396-406
-
Tidskriftsartikel (refereegranskat)abstract
- PURPOSE:Regrowth of tumour cells between cycles of chemotherapy is a significant clinical problem. Treatment strategies where antiproliferative agents are used to inhibit tumour regrowth between chemotherapy cycles are attractive, but such strategies are difficult to test using conventional monolayer culture systems.METHODS:We used the in vitro tumour spheroid model to study regrowth of 3-D colon carcinoma tissue after cytotoxic therapy. Colon carcinoma cells with wild-type or mutant phosphatidyl inositol 3-kinase catalytic subunit (PI3KCA) or KRAS alleles were allowed to form multicellular spheroids and the effects of different pharmacological compounds were studied after sectioning and staining for relevant markers of cell proliferation and apoptosis.RESULTS:Studies using colon cancer cells with gene disruptions suggested that the phosphoinositide 3-kinase (PI3K)-mammalian target of rapamycin (mTOR) pathway was essential for proliferation in 3-D culture. The dual PI3K-mTOR inhibitor NVP-BEZ235, currently in clinical trials, was found to inhibit phosphorylation of the mTOR target 4EBP1 in 3-D cultured cells. The ability of NVP-BEZ235 to inhibit tumour cell proliferation and to induce apoptosis was markedly more pronounced in 3-D cultures compared to monolayer cultures. It was subsequently found that NVP-BEZ235 was effective in inhibiting regrowth of 3-D cultured cells after treatment with two cytotoxic inhibitors of the ubiquitin-proteasome system (UPS), methyl-13-hydroxy-15-oxokaurenoate (MHOK) and bortezomib (Velcade®).CONCLUSIONS:The dual PI3K-mTOR inhibitor NVP-BEZ235 was found to reduce cell proliferation and to induce apoptosis in 3-D cultured colon carcinoma cells, NVP-BEZ235 is a promising candidate for use in sequential treatment modalities together with cytotoxic drugs to reduce the cell mass of solid tumours.
|
|
| 8. |
- Hillert, Ellin-Kristina, et al.
(författare)
-
Proteasome inhibitor b-AP15 induces enhanced proteotoxicity by inhibiting cytoprotective aggresome formation
- 2019
-
Ingår i: Cancer Letters. - : ELSEVIER IRELAND LTD. - 0304-3835 .- 1872-7980. ; 448, s. 70-83
-
Tidskriftsartikel (refereegranskat)abstract
- Proteasome inhibitors have been shown to induce cell death in cancer cells by triggering an acute proteotoxic stress response characterized by accumulation of poly-ubiquitinated proteins, ER stress and the production of reactive oxygen species. The aggresome pathway has been described as an escape mechanism from proteotoxicity by sequestering toxic cellular aggregates. Here we show that b-AP15, a small-molecule inhibitor of proteasomal deubiquitinase activity, induces poly-ubiquitin accumulation in absence of aggresome formation. b-AP15 was found to affect organelle transport in treated cells, raising the possibility that microtubule-transport of toxic protein aggregates is inhibited, leading to enhanced cytotoxicity. In contrast to the antiproliferative effects of the clinically used proteasome inhibitor bortezomib, the effects of b-AP15 are not further enhanced by the histone deacetylase inhibitor suberoylanilide hydroxamic acid (SAHA). Our results suggest an inhibitory effect of b-AP15 on the transport of misfolded proteins, resulting in a lack of aggresome formation, and a strong proteotoxic stress response.
|
|
| 9. |
- Li, Ze, et al.
(författare)
-
Modulated-Virtual-Vector-Based Predictive Current Control for Dual Three-Phase PMSM With Enhanced Steady-State Performance
- 2023
-
Ingår i: IECON 2023 - 49th Annual Conference of the IEEE Industrial Electronics Society. - : Institute of Electrical and Electronics Engineers (IEEE).
-
Konferensbidrag (refereegranskat)abstract
- Dual three-phase permanent magnet synchronous machine (DTP-PMSM) has attracted great attention due to its high reliability and high-power output capacities. However, the conventional single-voltage-vector-based predictive current control (SV-PCC) for DTP-PMSM presents high torque ripple and current harmonics, and high computational burden. To solve those issues, a modulated-virtual-vector-based PCC (MVV-PCC) for DTP-PMSM is proposed in this paper. Wherein, twenty-four VVs are synthesized by the inherent voltage vectors, and two VVs and one zero voltage vector with optimal duty cycles are determined and applied in each sampling period to improve the steady-state performance. The selection of optimal VVs and the calculation of the optimal duty cycles are simplified by integrating the deadbeat control and modulation scheme. Various comparisons are carried out to validate the effectiveness and superiority of the proposed MVV-PCC strategy.
|
|
| 10. |
- Li, Ze, et al.
(författare)
-
Multi-Virtual-Vector-Based Predictive Current Control for Fault-Tolerant Inverter-Fed Dual Three-Phase Permanent Magnet Synchronous Machines
- 2023
-
Ingår i: 2023 IEEE International Conference on Predictive Control of Electrical Drives and Power Electronics, PRECEDE 2023. - : Institute of Electrical and Electronics Engineers (IEEE).
-
Konferensbidrag (refereegranskat)abstract
- Dual three-phase permanent magnet synchronous machine (DTP-PMSM) has received extensive interests due to its inherent fault-tolerant capability. However, conventional single-virtual-vector-based predictive current control (SVV-PCC) for DTP-PMSM with open-phase fault (OPF) presents poor steady-state performance and high computational burden. To address these issues, a multi-virtual-vector-based PCC (MVV-PCC) for DTP-PMSM with OPF is proposed in this paper. Therein, two virtual vectors and one zero vector with optimal duty cycles are determined in each sampling period to improve the steady-state performance. A simplification strategy for selecting the optimal virtual vectors and calculating the optimal duty cycles is established to reduce the computational burden in digital implementation. Extensive comparisons are conducted to verify the effectiveness of the proposed MVV-PCC scheme.
|
|
