| 1. |
- Elo, Mika, et al.
(author)
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Differential regulation of stress proteins by high hydrostatic pressure, heat shock, and unbalanced calcium homeostasis in chondrocytic cells.
- 2000
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In: Journal of Cellular Biochemistry. - : John Wiley & Sons. - 0730-2312 .- 1097-4644. ; 79:4, s. 610-619
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Journal article (peer-reviewed)abstract
- High hydrostatic pressure (HP) has recently been shown to increase cellular heat shock protein 70 (Hsp70) level in a specific way that does not involve transcriptional activation of the gene, but rather the stabilisation of the mRNA for Hsp70. In this study, we investigated whether there are other observable changes caused by HP stress, and compared them with those induced by certain other forms of stressors. A chondrocytic cell line T/C28a4 was exposed to 30 MPa continuous HP, heat shock at 43 degrees C, and increased cytosolic calcium concentration by the addition of sarco-endoplasmic reticulum Ca(2+) ATPase inhibitor thapsigargin (25 nM) or calcium ionophore A23187 (1 microM) in the cultures. The protein synthesis was studied by in vitro metabolic labelling followed by one- and two-dimensional polyacrylamide gel electrophoresis, and mass spectrometry was utilized to confirm the identity of the protein spots on two-dimensional gels. Continuous 30 MPa HP increased remarkably the relative labelling of Hsp70. Labelling of Hsp90 was also increased by 15-20%, although no clear change was evident at the protein level in Western blots. Elevated intracellular Ca(2+) concentration induced by thapsigargin and calcium ionophore A23187 increased mainly the synthesis of glucose-regulated protein 78 (Grp78/BiP), whereas Hsp70 and Hsp90 were decreased by the treatment. Heat shock was the strongest inducer of Hsp70 and Hsp90. This study further confirmed the induction of Hsp70 in chondrocytic cells exposed to high HP, but it also showed that calcium-mediated responses are unlikely to cause the stress response observed in the hydrostatically pressurized cells.
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| 2. |
- Elo, Mika, et al.
(author)
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Specific induction of heat shock protein 90beta by high hydrostatic pressure.
- 2003
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In: Biorheology. - : IOS Press. - 0006-355X .- 1878-5034. ; 40:1-3, s. 141-146
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Journal article (peer-reviewed)abstract
- In chondrocytes, a low-amplitude intermittent hydrostatic pressure induces production of extracellular matrix molecules, while high hydrostatic pressure inhibits it. High pressure increases cellular heat shock protein 70 level in a number of cell types on account of increased stabilisation of the heat shock protein 70 mRNA. In our experiments, only bovine primary chondrocytes, but not an immortalized chondrocytic cell line, could resist the induction of the stress response in the presence of continuous 30 MPa hydrostatic pressure. We have recently shown that protein synthesis is required for the stabilization. According to two-dimensional gel electrophoresis the synthesis of heat shock protein 90 was also increased in a chondrocytic cell line and in HeLa cells, and mass spectrometric analysis suggested that the induction was rather due to increase in heat shock protein 90beta than in heat shock protein 90alpha. The stress response was rather intense in HeLa cells, therefore, we investigated the effect of continuous 30 MPa hydrostatic pressure on the expression of the two heat shock protein 90 genes in HeLa cells using Northern and Western blot analyses. Heat shock protein 90beta mRNA level increased within 6 hours of exposure to 30 MPa hydrostatic pressure, while hsp90alpha level remained stable. At protein level there was a clear increase in the heat shock protein 90beta/heat shock protein 90alpha ratio, too. These results show a specific regulation of stress proteins in cells exposed to high hydrostatic pressure.
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| 3. |
- Kaarniranta, Kai, et al.
(author)
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Neuronal cells show regulatory differences in the hsp70 gene response.
- 2002
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In: Brain Research. Molecular Brain Research. - : Elsevier. - 0169-328X .- 1872-6941. ; 101:1-2, s. 136-140
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Journal article (peer-reviewed)abstract
- The synthesis of heat shock proteins (Hsps), encoded by heat shock genes, is increased in response to various stress stimuli. Hsps function as molecular chaperones, they dissociate cytotoxic stress-induced protein aggregates within cells and ensure improved survival. Induction of heat shock genes is mainly regulated at the transcriptional level. The stress responsive transcription factor, heat shock factor 1 (HSF1), is involved in the transcriptional induction of the heat shock genes. Our objective was to examine how hsp70 genes are regulated in different transformed and primary neurons upon exposure to elevated temperature. Our findings reveal that the Hsp70 response is regulated at the translational level in Neuro-2a neuroblastoma cells, while the IMR-32 neuroblastoma cells respond to stress by the classical HSF1-driven transcriptional regulatory mechanism. Primary rat hippocampal neurons show a lack of HSF1 and induction of the hsp70 gene. These observations suggest that neuronal cells display different hsp70 gene expression patterns which range from undetected response to transcriptional and posttranscriptional regulation during heat stress.
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| 4. |
- Kaarniranta, Kai, et al.
(author)
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Primary chondrocytes resist hydrostatic pressure-induced stress while primary synovial cells and fibroblasts show modified Hsp70 response.
- 2001
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In: Osteoarthritis and Cartilage. - : Saunders Elsevier. - 1063-4584 .- 1522-9653. ; 9:1, s. 7-13
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Journal article (peer-reviewed)abstract
- OBJECTIVE: During joint loading, chondrocytes in the articular cartilage are subjected to gradients of high compressive hydrostatic pressure (HP). In response to diverse chemical or physical stresses, heat shock genes are induced to express heat shock proteins (Hsps). This study sought to examine the role of Hsps in baroresistance in primary bovine chondrocytes and synovial cells, as well as in primary human fibroblasts.METHODS: Northern blotting was used to analyze the steady-state levels of hsp70 mRNA in the primary cells exposed to HP or heat stress. Hsp70 protein accumulation was analyzed by Western blotting, and the DNA-binding activity was examined by gel mobility shift assay.RESULTS: Primary bovine chondrocytes which have been adapted to live under pressurized conditions showed negligible Hsp70 response upon HP loading, whereas primary bovine synovial cells and human fibroblasts accumulated hsp70 mRNA and protein when subjected to HP. The response was initiated without activation of the heat shock transcription factor 1. Interestingly, pre-conditioning of the barosensitive fibroblasts with HP or heat shock reduced the Hsp70 response, indicating induction of baroresistance.CONCLUSION: This study suggests that Hsp70 can play an important role in the early stages of adaptation of cells to HP. Thus, the Hsp70 gene expression upon HP loading may serve as one indicator of the chondrocytic phenotype of the cells. This can be of use in the treatment of cartilage lesions.
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| 5. |
- Kaarniranta, Kai, et al.
(author)
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Protein synthesis is required for stabilization of hsp70 mRNA upon exposure to both hydrostatic pressurization and elevated temperature.
- 2000
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In: FEBS Letters. - : Elsevier. - 0014-5793 .- 1873-3468. ; 475:3, s. 283-286
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Journal article (peer-reviewed)abstract
- We have recently described that in chondrocytic cells high hydrostatic pressure (HP) causes a heat shock response via mRNA stabilization without a transcriptional activation of the hsp70 gene. In this study, we investigated whether this exceptional regulatory mechanism occurs more generally in different types of cells. Indeed, hsp70 mRNA and protein accumulated in HeLa, HaCat and MG-63 cells under 30 MPa HP, without DNA-binding of heat shock transcription factor 1 (HSF1) to the heat shock element of the hsp70 gene or formation of nuclear HSF1 granules, revealing a lack of transcriptional activation. Moreover, we observed that protein synthesis is needed for mRNA stabilization. Thus, high HP offers a model to study the mechanisms of hsp70 mRNA stabilization without HSF1-mediated induction of the heat shock gene response.
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| 6. |
- Kaarniranta, Kai, et al.
(author)
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Silmäpohjan rappeumatauti - vaikea ongelma lääkärille [Age-related macular degeneration--a difficult problem for the patient and for the ophthalmologist].
- 2003
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In: Duodecim. - 0012-7183 .- 2242-3281. ; 119:10, s. 935-942
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Journal article (peer-reviewed)abstract
- Silmänpohjan ikärappeuma on yleisin näkövammaisuutta aiheuttava silmäsairaus länsimaissa. Yli 65-vuotiaista 10–20 % kärsii sen aiheuttamista keskeisen näköalueen korjaantumattomista häiriöistä. Väestön vanhetessa ikärappeuman esiintyvyys on lisääntynyt. Sairauden kliiniset ja histopatologiset muutokset tunnetaan hyvin, mutta etiologia on tuntematon, ehkäisystä on niukasti tietoa ja hoitovaihtoehdot ovat vähäiset. Silmänpohjan ikärappeumasta on muodostunut yksi vaikeimmista ongelmista silmälääkäreille ja oftalmologian tutkijoille.
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| 7. |
- Kaarniranta, Kai, et al.
(author)
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Solustressin tutkimuksesta kliinisiin läpimurtoihin? [From research of cellular stress to various clinical break through innovations?]
- 2001
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In: Duodecim. - : Duodecim. - 0012-7183 .- 2242-3281. ; 117:22, s. 2266-2272
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Research review (peer-reviewed)abstract
- Fysikaalisen tai kemiallisen stressin seurauksena useiden geenien aktiivisuus vähenee,kun taas lämpösokki- eli stressigeenien induktio lisääntyy. Stressigeenit koodaavat lämpösokkiproteiineja(Hsp), jotka toimivat soluissa kaperoneina, »avustajina», auttaensolujen proteiineja laskostumaan oikein translaatiossa, kalvon läpi kuljetuksessa tai esimerkiksikorkean lämpötilan aiheuttaman vaurion jälkeen. Viime vuosina lämpösokkiproteiinienkliininen merkitys useiden sairauksien patogeneesissä, diagnostiikassa ja ennusteenmäärittämisessä on alkanut selvitä. Merkittävimmät kliiniset löydökset liittyvätiskeemisiin prosesseihin, kuten sydän- ja aivoinfarkteihin, useisiin neoplasioihin ja ikääntymiseen.Tässä katsauksessa käsittelemme stressigeenien säätelyä, Hsp70-stressiproteiinienkliinisiä yhteyksiä ja niiden mahdollisia hoitosovelluksia iskeemisissä, neoplastisissaja degeneratiivisissa prosesseissa.
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| 8. |
- Kaarniranta, Kai, et al.
(author)
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Stress responses of mammalian cells to high hydrostatic pressure.
- 2003
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In: Biorheology. - : IOS Press. - 0006-355X .- 1878-5034. ; 40:1-3, s. 87-92
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Journal article (peer-reviewed)abstract
- High hydrostatic pressure causes stress response in many types of mammalian cells. We have previously shown that an accumulation of heat shock protein 70 (Hsp70) in a chondrocytic cell line occurred without an activation of the gene itself. Stabilization of the hsp70 mRNA was shown to be the reason for the Hsp70 stress response in the pressurized cells. Since accumulation of Hsp70 in pressurized cells indicated that high hydrostatic pressure induces a stress response without heat shock transcription factor activation, we decided to investigate the activation of two other stress-associated transcription factors, activator protein-1 (AP-1) and nuclear factor-kappaB (NF-kappaB). Induction of Hsp70 in immortalized and primary chondrocytes, murine Neuro-2a neuroblastoma and HeLa cervical carcinoma cell lines was investigated at both mRNA and protein levels. In immortalized chondrocytes and HeLa cells, hsp70 mRNA levels were clearly elevated after 6 hours of the onset of 30 MPa continuous hydrostatic pressure, while in primary chondrocytes and Neuro-2a cells (the cells known to be stress-sensitive) no induction was observed. Surprisingly, neither heat shock nor high hydrostatic pressure could induce the hsp70 mRNA in Neuro-2a cells, although an activation of heat shock transcription factor could be observed in heat-shocked cells. No activation of the AP-1 and NF-kappaB binding to their target DNA sequences could be shown in the immortalized chondrocytes.
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| 9. |
- Karjalainen, Hannu, et al.
(author)
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Gene expression profiles in chondrosarcoma cells subjected to cyclic stretching and hydrostatic pressure. A cDNA array study.
- 2003
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In: Biorheology. - : IOS Press. - 0006-355X .- 1878-5034. ; 40:1-3, s. 93-100
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Journal article (peer-reviewed)abstract
- Mechanical forces have a profound effect on cartilage tissue and chondrocyte metabolism. Strenuous loading inhibits the cellular metabolism, while optimal level of loading at correct frequency raises an anabolic response in chondrocytes. In this study, we used Atlas Human Cancer cDNA array to investigate mRNA expression profiles in human chondrosarcoma cells stretched 8% for 6 hours at a frequency of 0.5 Hz. In addition, cultures were exposed to continuous and cyclic (0.5 Hz) 5 MPa hydrostatic pressure. Cyclic stretch had a more profound effect on the gene expression profiles than 5 MPa hydrostatic pressure. Several genes involved with the regulation of cell cycle were increased in stretched cells, as well as mRNAs for PDGF-B, glucose-1-phosphate uridylyltransferase, Tiam1, cdc37 homolog, Gem, integrin alpha6, and matrix metalloproteinase-3. Among down-regulated genes were plakoglobin, TGF-alpha, retinoic acid receptor-alpha and Wnt8b. A smaller number of changes was detected after pressure treatments. Plakoglobin was increased under cyclic and continuous 5 MPa hydrostatic pressure, while mitogen-activated protein kinase-9, proliferating cell nuclear antigen, Rad6, CD9 antigen, integrins alphaE and beta8, and vimentin were decreased. Cyclic and continuous pressurization induces a number of specific changes. In conclusion, a different set of genes were affected by three different types of mechanical stimuli applied on chondrosarcoma cells.
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| 10. |
- Lammi, Mikko, 1961-, et al.
(author)
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Hydrostatic pressure-induced changes in cellular protein synthesis.
- 2004
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In: Biorheology. - : IOS Press. - 0006-355X .- 1878-5034. ; 41:3-4, s. 309-313
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Research review (peer-reviewed)abstract
- Hydrostatic pressure is a well-known effector of cellular protein synthesis. High continuous hydrostatic pressure inhibits protein synthesis in general. It has been known for a long time that 30S ribosomal subunit is associated with the effects of pressure on protein synthesis in prokaryotes, however, the mechanisms of action are still not completely understood. Our new data suggest that synthesis of eukaryotic elongation factor-2 (eEF-2) is decreased under 30 MPa continuous hydrostatic pressure. Thus, eEF-2 may have a role in the synthesis of pressure-regulated proteins in eukaryotic cells. The presence of pressure-sensitive proteins indicate that hydrostatic pressure can induce very specific responses in stressed cells. Accumulation of heat shock protein 70 and 90 beta occurs under high pressure, independent of the general inhibition of protein synthesis, although this response appears clearly weaker than during heat stress.
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