| 1. |
- Berg, Cecilia, 1976-, et al.
(författare)
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Platelets induce reactive oxygen species-dependent growth of human skin fibroblasts
- 2003
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Ingår i: European Journal of Cell Biology. - : Elsevier BV. - 0171-9335 .- 1618-1298. ; 82:11, s. 565-571
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Tidskriftsartikel (refereegranskat)abstract
- A growing amount of evidence suggests that reactive oxygen species (ROS), such as hydrogen peroxide and superoxide anion, regulate intracellular signalling and have a role in cell proliferation. In the present study, we show that platelets increase the mitogenic rate in human fibroblasts and that this effect was inhibited by the intracellular antioxidant N-acetyl-L-cysteine (NAC) and the NADPH-oxidase inhibitor diphenyleneiodonium chloride (DPI). The mitogenic effects of platelets were mimicked by the platelet factors platelet-derived growth factor BB-isoform (PDGF-BB), transforming growth factor β1 (TGF-β1) and sphingosine-1-phosphate (S1P). The sphingosine kinase inhibitor DL-threo-dihydrosphingosine (DL-dihydro) abrogated the platelet-induced growth, while antibodies directed against PDGF or TGF-β had modest effects. Exposure of fibroblasts to platelets, PDGF-BB, TGF-β1 or S1P caused an extensive intracellular ROS production, measured as changes in dichlorofluorescein fluorescence. This ROS production was totally inhibited by NAC, pyrrolidinethiocarbamate (PDTC), DPI and apocynin. In conclusion, the results presented are indicative of a crucial role of ROS in the platelet-mediated regulation of fibroblast proliferation.
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| 2. |
- Grenklo, Staffan, et al.
(författare)
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Anti-actin antibodies generated against profilin : actin distinguish between non-filamentous and filamentous actin, and label cultured cells in a dotted pattern
- 2004
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Ingår i: European Journal of Cell Biology. - : Elsevier BV. - 0171-9335 .- 1618-1298. ; 83:8, s. 413-423
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Tidskriftsartikel (refereegranskat)abstract
- Actin polymerization is a prominent feature of migrating cells, where it powers the protrusion of the leading edge. Many studies have characterized the well-ordered and dynamic arrangement of filamentous actin in this submembraneous space. However, less is known about the organization of unpolymerized actin. Previously, we reported on the use of covalently coupled profilin:actin to study actin dynamics and presented evidence that profilin-bound actin is a major source of actin for filament growth. To locate profilin:actin in the cell we have now used this non-dissociable complex for antibody generation, and obtained monospecific anti-actin and antiprofilin antibodies from two separate immunizations. Fluorescence microscopy revealed drastic differences in the staining pattern generated by the anti-actin antibody preparations. With one, distinct puncta appeared at the actin-rich leading edge and sometimes aligned with microtubules in the interior of the lamella, while the other displayed typical actin filament staining. Labelling experiments in vitro demonstrated failure of the first antibody to recognize filamentous actin and none of the two bound microtubules. The two anti-profilin antibodies purified in parallel generated a punctated pattern similar to that seen with the first anti-actin antibody. All antibody preparations labelled the nuclei.
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| 3. |
- Larsson, M., et al.
(författare)
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The spatial and temporal expression of Tekt1, a mouse tektin C homologue, during spermatogenesis suggest that it is involved in the development of the sperm tail basal body and axoneme
- 2000
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Ingår i: European Journal of Cell Biology. - : Elsevier BV. - 0171-9335 .- 1618-1298. ; 79:10, s. 718-725
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Tidskriftsartikel (refereegranskat)abstract
- Tektins comprise a family of filament-forming proteins that are known to be coassembled with tubulins to form ciliary and flagellar microtubules. Recently we described the sequence of the first mammalian tektin protein, Tekt1 (from mouse testis), which is most homologous with sea urchin tektin C. We have now investigated the temporal and spatial expression of Tekt1 during mouse male germ cell development. By in situ hybridization analysis TEKT1 RNA expression is detected in spermatocytes and in round spermatids in the mouse testis, Immunofluorescence microscopy analysis with anti-Tekt1 antibodies showed no distinct labeling of any subcellular structure in spermatocytes, whereas in round spermatids anti-Tekt1 antibodies co-localize with anti-ANA antibodies to the centrosome. At a later stage, elongating spermatids display a larger area of anti-Tekt1 staining at their caudal ends; as spermiogenesis proceeds, the anti-Tekt1 staining disappears. Together with other evidence, these results provide the first intraspecies evidence that Tekt1 is transiently associated with the centrosome, and indicates that Tekt1 is one of several tektins to participate in the nucleation of the flagellar axoneme of mature spermatozoa, perhaps being required to assemble the basal body.
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| 4. |
- Xin, Sun, et al.
(författare)
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A novel protein localized to the fibrillar compartment of the nucleolus and to the brush border of a secretory cell
- 2002
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Ingår i: European Journal of Cell Biology. - : Elsevier BV. - 0171-9335 .- 1618-1298. ; 81:3, s. 125-137
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Tidskriftsartikel (refereegranskat)abstract
- We report the identification and molecular characterization of a novel abundant nucleolar protein of the dipteran Chironomus tentans. As shown by Western blot analysis, this protein is present in nuclear extracts in a phosphorylated form with a mobility corresponding to 100 kDa. Therefore, the protein has been termed Chironomus tentans p100, or p100 for short. Analysis of the cDNA-derived primary structure of p100 indicates a protein that contains a combination of structural domains which could be involved in interactions with proteins and nucleic acids: twelve alternating acidic and basic repeats, a glycine-arginine-rich domain and a region with two zinc fingers of the C4-type. Acidic and basic repeats are typical for a group of nonribosomal nucleolar proteins. The best-studied representatives of this group are Nopp140 and nucleolin, proteins with structural and regulatory functions in rDNA transcription. Immunocytology and immunoelectron microscopy of Chironomus tentans salivary gland cells have shown that the p100 protein is located in the fibrillar compartment of the nucleolus, while it is almost absent from the granular compartment and from the nucleoplasm. The p100 protein remains in the nucleolus after removal of RNA and DNA by digestion with nucleases. This indicates that p100 might be a constituent of the nucleolar proteinaceous framework. Remarkably, p100 is also localized in the brush border in the apical part of the salivary gland cell. The presence of p100 both in the nucleolus and at the apical plasma membrane suggests that it could be involved in coordination of the level of protein production and export from the cell through regulation of the level of rRNA production in the nucleolus.
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| 5. |
- Akner, Gunnar, 1953-, et al.
(författare)
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Evidence for reversible, non-microtubule and non-microfilament-dependent nuclear translocation of hsp90 after heat shock in human fibroblasts
- 1992
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Ingår i: European Journal of Cell Biology. - 0171-9335 .- 1618-1298. ; 58:2, s. 356-364
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Tidskriftsartikel (refereegranskat)abstract
- A monoclonal antibody (29A) directed against rat liver heat shock protein M(r) 90,000 (hsp90) was produced. By Western immunoblotting of cytosols prepared from several different tissues and species, 29A was shown to specifically recognize only one band with M(r) approximately 90,000. Localization of hsp90 in human gingival fibroblasts was studied using the 29A antibody by indirect mono- and double-staining immunofluorescence and confocal laser scanning microscopy. The distribution was compared to that of the glucocorticoid receptor (GR) and various cytoskeletal structures. Cells were analyzed in interphase and mitosis under basal culture conditions, after heat shock and after microtubule and microfilament depolymerization, sometimes combined with heat shock. A major part of hsp90 immunoreactivity was diffusely distributed throughout the interphase cytoplasm, but a weak nuclear staining with non-stained nucleoli was also present, however, only detectable after methanol and not after formaldehyde/Triton X-100 fixation. Heat shock induced a time-dependent translocation of hsp90 from the cytoplasm to the cell nucleus reaching a plateau after 15 h. This compartment shift was reversible and also occurred in the absence of intact microtubules or intact microfilaments.
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| 6. |
- Akner, Gunnar, 1953-, et al.
(författare)
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Immunocytochemical localization of glucocorticoid receptor in human gingival fibroblasts and evidence for a colocalization of glucocorticoid receptor with cytoplasmic microtubules
- 1990
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Ingår i: European Journal of Cell Biology. - 0171-9335 .- 1618-1298. ; 53:2, s. 390-401
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Tidskriftsartikel (refereegranskat)abstract
- The cellular distribution of the glucocorticoid receptor (GR) in relation to various intracellular and plasma membrane structures in human fibroblasts was studied using indirect immunofluorescence techniques with monoclonal and polyclonal antibodies. During interphase, GR was located predominantly in the cytoplasm, showing a similar pattern as tubulin. In mitotic cells, GR and tubulin were localized in mitotic spindles and in telophase midbodies. Colchicine and vinblastine induced a similar redistribution of GR and tubulin to the cell periphery. This redistribution was reversible for colchicine but not for vinblastine. Vinblastine also induced paracrystals containing GR and tubulin. These results support the hypothesis that GR interacts in vivo with cytoplasmic microtubules.
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| 7. |
- Bengtsson, T., et al.
(författare)
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Actin dynamics in human neutrophils during adhesion and phagocytosis is controlled by changes in intracellular free calcium
- 1993
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Ingår i: European Journal of Cell Biology. - Jena, Germany : Urban und Fischer Verlag. - 0171-9335 .- 1618-1298. ; 62:1, s. 19-58
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Tidskriftsartikel (refereegranskat)abstract
- The role of changes in cytosolic free calcium concentration ([Ca2+]i) in the assembly and disassembly of actin during adhesion and phagocytosis was evaluated. Rhodamine-phalloidin staining combined with quantitative fluorescence and confocal laser scanning microscopy was used to measure local F-actin changes in single adherent human neutrophils phagocytosing yeast particles on different surfaces and under different calcium conditions. Cells were suspended in a) calcium-containing medium (CCM) or b) calcium-free medium (CFM) or c) were first depleted of calcium (i.e., MAPT/AM-loaded in CFM) and then suspended in CFM (MAPT). In parallel, local [Ca2+]i changes were monitored using a fura-2 ratio imaging system. In CCM or CFM, attachment to the substrate and formation of pseudopods around a yeast particle generated, within a few seconds, rises in [Ca2+]i, both around the phagosome and in the cell body. During continued phagocytosis, [Ca2+]i was more elevated around the phagosome compared to the rest of the cell. No [Ca2+]i fluctuations were observed in MAPT cells. Adhesion and phagocytosis led to a several-fold increase in F-actin. The increase was transient in cells in CCM and CFM, but remained high in Ca-depleted neutrophils. A distinct ring of F-actin was formed around a phagosome with a yeast particle. Twenty min after ingestion the amount of this actin decreased more than 50% in CCM and CFM cells but increased by 40 to 100% in MAPT cells. The accumulation of F-actin in MAPT cells was reduced to resting levels by adding Ca2+ and ionomycin after ingestion. This treatment reestablished the periphagosomal [Ca2+]i rises, as observed in CCM cells. In conclusion, the present study shows that the actin polymerization, occurring in human neutrophils during adhesion and phagocytosis, is not influenced by changes in [Ca2+]i, whereas the subsequent depolymerization is. The accumulation of actin filaments around the phagosome in calcium-depleted cells could be involved in the inhibition of phagolysosome fusion seen in the absence of [Ca2+]i changes (Jaconi et al., J. Cell Biol. 110, 1555-1564 (1990)). This suggests that the actin network, controlled by [Ca2+]i, regulates the movement of granules during phagocytosis.
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| 8. |
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| 9. |
- Cong, Goh Zheng, et al.
(författare)
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Targeted pancreatic beta cell imaging for early diagnosis
- 2020
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Ingår i: European Journal of Cell Biology. - : Elsevier BV. - 0171-9335 .- 1618-1298. ; 99:7
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Forskningsöversikt (refereegranskat)abstract
- Pancreatic beta cells are important in blood glucose level regulation. As type 1 and 2 diabetes are getting prevalent worldwide, we need to explore new methods for early detection of beta cell-related afflictions. Using bioimaging techniques to measure beta cell mass is crucial because a decrease in beta cell density is seen in diseases such as diabetes and thus can be a new way of diagnosis for such diseases. We also need to appraise beta cell purity in transplanted islets for type 1 diabetes patients. Sufficient amount of functional beta cells must also be determined before being transplanted to the patients. In this review, indirect imaging of beta cells will be discussed. This includes membrane protein on pancreatic beta cells whereby specific probes are designed for different imaging modalities mainly magnetic resonance imaging, positron emission tomography and fluorescence imaging. Direct imaging of insulin is also explored though probes synthesized for such function are relatively fewer. The path for successful pancreatic beta cell imaging is fraught with challenges like non-specific binding, lack of beta cell-restricted targets, the requirement of probes to cross multiple lipid layers to bind to intracellular insulin. Hence, there is an urgent need to develop new imaging techniques and innovative probing constructs in the entire imaging chain of bioengineering to provide early detection of beta cell-related pathology.
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| 10. |
- Eriksson, Ida, et al.
(författare)
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Impact of high cholesterol in a Parkinsons disease model: Prevention of lysosomal leakage versus stimulation of alpha-synuclein aggregation
- 2017
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Ingår i: European Journal of Cell Biology. - : ELSEVIER GMBH, URBAN & FISCHER VERLAG. - 0171-9335 .- 1618-1298. ; 96:2, s. 99-109
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Tidskriftsartikel (refereegranskat)abstract
- Parkinsons disease is characterized by accumulation of intraneuronal cytoplasmic inclusions, Lewy bodies, which mainly consist of aggregated alpha-synuclein. Controversies exist as to whether high blood cholesterol is a risk factor for the development of the disease and whether statin treatment could have a protective effect. Using a model system of BE(2)-M17 neuroblastoma cells treated with the neurotoxin 1-methyl-4-phenylpyridinium (MPP+), we found that MPP+-induced cell death was accompanied by cholesterol accumulation in a lysosomal-like pattern in pre-apoptotic cells. To study the effects of lysosomal cholesterol accumulation, we increased lysosomal cholesterol through pre-treatment with U18666A and found delayed leakage of lysosomal contents into the cytosol, which reduced cell death. This suggests that increased lysosomal cholesterol is a stress response mechanism to protect lysosomal membrane integrity in response to early apoptotic stress. However, high cholesterol also stimulated the accumulation of alpha-synuclein. Treatment with the cholesterol-lowering drug lovastatin reduced MPP+-induced cell death by inhibiting the production of reactive oxygen species, but did not prevent lysosomal cholesterol increase nor affect alpha-synuclein accumulation. Our study indicates a dual role of high cholesterol in Parkinsons disease, in which it acts both as a protector against lysosomal membrane permeabilization and as a stimulator of alpha-synuclein accumulation. (C) 2017 Elsevier GmbH. All rights reserved.
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