| 1. |
- Rilla, Kirsi, et al.
(författare)
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Changed lamellipodial extension, adhesion plaques and migration in epidermal keratinocytes containing constitutively expressed sense and antisense hyaluronan synthase 2 (Has2) genes.
- 2002
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Ingår i: Journal of Cell Science. - Cambridge : The Company of Biologists. - 0021-9533 .- 1477-9137. ; 115, s. 3633-3643
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Tidskriftsartikel (refereegranskat)abstract
- Hyaluronan is a major component of the epidermal extracellular matrix, is actively synthesized by keratinocytes and shows fast matrix turnover in the stratified epithelium. We probed the importance of hyaluronan synthesis in keratinocytes by establishing cell lines carrying the exogenous hyaluronan synthase 2 (Has2) gene in sense and antisense orientations to increase and decrease their hyaluronan synthesis, respectively. Compared with cell lines transfected with the vector only, most clones containing the Has2 sense gene migrated faster in an in vitro wounding assay, whereas Has2 antisense cells migrated more slowly. Has2 antisense clones showed delayed entry into the S phase of cell cycle following plating, smaller lamellipodia and less spreading on the substratum. The decrease of hyaluronan on the undersurface of Has2 antisense cells was associated with an increased area of adhesion plaques containing vinculin. Exogenous hyaluronan added to the keratinocyte cultures had a minor stimulatory effect on migration after wounding but did not restore the reduced migratory ability of Has2 antisense cells. Hyaluronan decasaccharides that displace receptor bound hyaluronan in keratinocytes, and Streptomyces hyaluronidase sufficient to remove most cell surface hyaluronan had little effect on cell migration. The results suggest that the dynamic synthesis of hyaluronan directed by Has2, rather than the abundance of pericellular hyaluronan, controls keratinocyte migration, a cell function vital for the repair of squamous epithelia following wounding.
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| 2. |
- Sironen, Reijo, et al.
(författare)
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cDNA array reveals mechanosensitive genes in chondrocytic cells under hydrostatic pressure.
- 2002
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Ingår i: Biochimica et Biophysica Acta. - : Elsevier. - 0006-3002 .- 1878-2434. ; 1591:1-3, s. 45-54
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Tidskriftsartikel (refereegranskat)abstract
- Hydrostatic pressure (HP) has a profound effect on cartilage metabolism in normal and pathological conditions, especially in weight-bearing areas of the skeletal system. As an important component of overall load, HP has been shown to affect the synthetic capacity and well-being of chondrocytes, depending on the mode, duration and magnitude of pressure. In this study we examined the effect of continuous HP on the gene expression profile of a chondrocytic cell line (HCS-2/8) using a cDNA array containing 588 well-characterized human genes under tight transcriptional control. A total of 51 affected genes were identified, many of them not previously associated with mechanical stimuli. Among the significantly up-regulated genes were immediate-early genes, and genes involved in heat-shock response (hsp70, hsp40, hsp27), and in growth arrest (GADD45, GADD153, p21(Cip1/Waf1), tob). Markedly down-regulated genes included members of the Id family genes (dominant negative regulators of basic helix-loop-helix transcription factors), and cytoplasmic dynein light chain and apoptosis-related gene NIP3. These alterations in the expression profile induce a transient heat-shock gene response and activation of genes involved in growth arrest and cellular adaptation and/or differentiation.
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| 3. |
- Sironen, Reijo, et al.
(författare)
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High pressure effects on cellular expression profile and mRNA stability. A cDNA array analysis.
- 2002
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Ingår i: Biorheology. - : IOS Press. - 0006-355X .- 1878-5034. ; 39:1-2, s. 111-117
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Tidskriftsartikel (refereegranskat)abstract
- Hydrostatic pressure has a profound effect on cartilage tissue and chondrocyte metabolism. Depending on the type and magnitude of pressure various responses can occur in the cells. The mechanisms of mechanotransduction at cellular level and the events leading to specific changes in gene expression are still poorly understood. We have previously shown that induction of stress response in immortalized chondrocytes exposed to high static hydrostatic pressure increases the stability of heat shock protein 70 mRNA. In this study, our aim was to examine the effect of high pressure on gene expression profile and to study whether stabilization of mRNA molecules is a general phenomenon under this condition. For this purpose a cDNA array analysis was used to compare mRNA expression profile in pressurized vs. non-pressurized human chondrosarcoma cells (HCS 2/8). mRNA stability was analyzed using actinomycin-treated and nontreated samples collected after pressure treatment. A number of immediate-early genes, and genes regulating cell cycle and growth were up-regulated due to high pressure. Decrease in osteonectin, fibronectin, and collagen types VI and XVI mRNAs was observed. Also bikunin, cdc37 homologue and Tiam1, genes linked with hyaluronan metabolism, were down-regulated. In general, stability of down-regulated mRNA species appeared to increase. However, no increase in mRNA above control level due to stabilization was noticed in the genes available in the array. On the other hand, mRNAs of certain immediate-early genes, like c-jun, jun-B and c-myc, became destabilized under pressure treatment. Increased accumulation of mRNA on account of stabilization under high pressure conditions seems to be a tightly regulated, specific phenomenon.
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| 4. |
- Tammi, Markku, et al.
(författare)
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EGF regulates HAS-2 expression, controls epidermal thickness and stimulates keratinocyte migration
- 2002
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Ingår i: Hyaluronan, Vol 1: Chemical, Biochemical and Biological Aspects. - Great Britain : Woodhead Publishing Limited. - 1855735709 ; , s. 561-570
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Konferensbidrag (refereegranskat)abstract
- High concentrations of hyaluronan reside in the small space between the vital kertinocyte layers of human and animal epidermis and influence keratinocyte interactions, including growth, mobility and differentiation. We have previously found that the content of epidermal hyaluronan in human skin organ cultures is decreased and increased by cortisol and retinoic acid, and associated with enhanced and retarded terminal differentiation, respectively. To further substantiate this idea, we incubated epidermal keratinocytes with epidermal growth factor (EGF), and found a marked increase in hyaluronan synthesis which correlated with faster migration in an in vitro wounding assay of keratinocyte monolayers. EGF increased hyaluronan also in stratified, differentiated organotypic cultures, and increased the height of vital epidermis and reduced the thickness of the cornified layers, findings in line with an inhibition of terminal differentiation of keratinocytes. The stimulation of hyaluronan synthesis by EGF was due to upregulation of hyaluronan synthase 2 (HAS2) but not HAS1 or HAS3. A part of the EGF influence on the structure of epidermis, and on skin wound healing, is thus mediated through its control of HAS2 expression.
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| 5. |
- Törrönen, Kari, et al.
(författare)
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Hyaluronan stimulates keratinocyte migration and activates the transcription factor AP-1 in keratinocytes through the JNK pathway
- 2002
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Ingår i: Hyaluronan, Vol 1: Chemical, Biochemical and Biological Aspects. - Great Britain : Woodhead Publishing Limited. - 1855735709 ; , s. 551-556
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Konferensbidrag (refereegranskat)abstract
- Hyaluronan (HA) has been considered a passive extracellular matrix (ECM) polysaccharide, but recent studies have shown its importance in controlling many cell functions including motility, proliferation and adhesion, which imply signaling from ECM to cytosol. Hyaluronan is a major ECM component in stratified epithelia such as skin epidermis. We found that hyaluronan added to the growth medium of newly plated human skin keratinocytes increased cell migration in an in vitro wound-healing assay. Hyaluronan also increased the transcription factor AP-1, as determined by gel shift assays. The kinase signals that apperently led to the increased AP-1 level were associated with the activation of c-Jun, mainly via the JNK pathway as early as 10 min after the addition of hyaluronan, and with the minimum concentration of 10 ng/ml. ERK1 was also slightly activated, while p38 MAPkinase was not affected.
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