Activation of heat-shock transcription factor 1 by hypertonic shock in 3T3 cells

Alfieri, Roberta; Petronini, Pier Giorgio; Urbani, Simona; Borghetti, Angelo F.

doi:10.1042/bj3190601

Cited by 28 publications

(17 citation statements)

References 39 publications

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“…A functional involvement of HSE restricted to seed desiccation, as demonstrated here, is consistent with the finding of HSF activation by hypertonic shock. In animal cells, immunological evidence has demonstrated that HSF1 is involved in this activation, rather than the developmentally regulated HSF2 (Alfieri et al, 1996). In plants, unpublished evidence discussed by Prä ndl and Schö ffl (1996) suggests a similar activation of plant HSF during desiccation in zygotic embryogenesis.…”

Section: Role Of Hse In the Developmental Regulation Of Ha Hsp177 G4mentioning

confidence: 99%

Dual regulation of a heat shock promoter during embryogenesis: stage‐dependent role of heat shock elements

1998

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SummaryTransgenic tobacco expression was analysed of chimeric genes with point mutations in the heat shock element (HSE) arrays of a small heat shock protein (sHSP) gene from sunflower: Ha hsp17.7 G4. The promoter was developmentally regulated during zygotic embryogenesis and responded to heat stress in vegetative tissues. Mutations in the HSE affected nucleotides crucial for human heat shock transcription factor 1 (HSF1) binding. They abolished the heat shock response of Ha hsp17.7 G4 and produced expression changes that demonstrated dual regulation of this promoter during embryogenesis. Thus, whereas activation of the chimeric genes during early maturation stages did not require intact HSE, expression at later desiccation stages was reduced by mutations in both the proximal (-57 to -89) and distal (-99 to -121) HSE. In contrast, two point mutations in the proximal HSE that did not severely affect gene expression during zygotic embryogenesis, eliminated the heat shock response of the same chimeric gene in vegetative organs. Therefore, by site-directed mutagenesis, it was possible to separate the heat shock response of Ha hsp17.7 G4 from its developmental regulation. The results indicate the co-existence, in a single promoter, of HSF-dependent and -independent regulation mechanisms that would control sHSP gene expression at different stages during plant embryogenesis.

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Section: Role Of Hse In the Developmental Regulation Of Ha Hsp177 G4mentioning

confidence: 99%

Dual regulation of a heat shock promoter during embryogenesis: stage‐dependent role of heat shock elements

1998

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“…To date, five target HSPs for this kind of stress have been identified: (1) two members of the HSP70 family, the highly stress-inducible HSP72 [29,31,80,100,106,108,120] and "Bip", the HSP of the endoplasmic reticulum [129]; (2) two small HSPs, HSP25/27 and αB-crystallin [34,54,64,100]; and (3) a new member of the HSP110 family, the so-called osmotic stress protein OSP94, which is highly inducible by hyperosmolality [68]. When cells are exposed to either hypo-or hypertonic medium the first reaction is the activation of the heat-shock-specific transcription factor, HSF, and DNA binding of this factor to the heat shock element (HSE) [1,57], pointing at a transcriptional regulation of the osmotically induced HSP expression.…”

Section: Heat Shock Proteinsmentioning

confidence: 99%

Cellular response to osmotic stress in the renal medulla

Beck¹,

Burger‐Kentischer²,

Müller³

1998

Pfl�gers Archiv European Journal of Physiology

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Cells of the renal medulla, which are exposed under normal physiological conditions to widely fluctuating extracellular solute concentrations, respond to hypertonic stress by accumulating the organic osmolytes glycerophosphorylcholine (GPC), betaine, myo-inositol, sorbitol and free amino acids. Increased intracellular contents of these osmolytes are achieved by a combination of increased uptake (myo-inositol and betaine) and synthesis (sorbitol, possibly GPC), decreased degradation (GPC) and reduced osmolyte release. In the medulla of the concentrating kidney, accumulation of organic osmolytes, which do not perturb cell function even at high concentrations, allows the maintenance of "normal" intracellular concentrations of inorganic electrolytes. Adaptation to decreasing extracellular solute concentrations, e.g. diuresis, is achieved primarily by activation of pathways allowing the efflux of organic osmolytes, and secondarily by inactivation of production (sorbitol) and uptake (betaine, myo-inositol) and stimulation of degradation (GPC). Apart from modulation of the osmolyte content, osmolality-dependent reorganization of the cytoskeleton and expression of specific stress proteins (heat shock proteins) may be further, as yet poorly characterized, components of the regulatory systems involved in the adaptation of medullary cells to osmotic stress.

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“…Heat shock proteins are also osmotically activated via increased transcription (12). Heat shock factor 1 is activated and binds heat shock element in 3T3 cells upon hyperosmotic shock (29).…”

Section: Table I Densitometric Quantification Of Phosphorylated and Nmentioning

confidence: 99%

Distinct Regulation of Osmoprotective Genes in Yeast and Mammals

Kültz

García-Peréz

Ferraris

et al. 1997

Journal of Biological Chemistry

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In yeast glycerol-3-phosphate dehydrogenase 1 is essential for synthesis of the osmoprotectant glycerol and is osmotically regulated via the high osmolarity glycerol (HOG1) kinase pathway. Homologous protein kinases, p38, and stress-activated protein kinase/Jun N-terminal kinase (SAPK/JNK) are hyperosmotically activated in some mammalian cell lines and complement HOG1 in yeast. In the present study we asked whether p38 or SAPK/JNK signal synthesis of the osmoprotectant sorbitol in rabbit renal medullary cells (PAP-HT25), analogous to the glycerol system in yeast. Sorbitol synthesis is catalyzed by aldose reductase (AR). Hyperosmolality increases AR transcription through an osmotic response element (ORE) in the 5-flanking region of the AR gene, resulting in elevated sorbitol. We tested if AR-ORE is targeted by p38 or SAPK/JNK pathways in PAP-HT25 cells. Hyperosmolality (adding 150 mM NaCl) strongly induces phosphorylation of p38 and of c-Jun, a specific target of SAPK/JNK. Transient lipofection of a dominant negative mutant of SAPK kinase, SEK1-AL, into PAP-HT25 cells specifically inhibits hyperosmotically induced c-Jun phosphorylation. Transient lipofection of a dominant negative p38 kinase mutant, MKK3-AL, into PAP-HT25 cells specifically suppresses hyperosmotic induction of p38 phosphorylation. We cotransfected either one of these mutants or their empty vector with an AR-ORE luciferase reporter construct and compared the hyperosmotically induced increase in luciferase activity with that in cells lipofected with only the AR-ORE luciferase construct. Hyperosmolality increased luciferase activity equally (5-7-fold) under all conditions. We conclude that hyperosmolality induces p38 and SAPK/JNK cascades in mammalian renal cells, analogous to inducing the HOG1 cascade in yeast. However, activation of p38 or SAPK/JNK pathways is not necessary for transcriptional regulation of AR through the ORE. This finding stands in contrast to the requirement for the HOG1 pathway for hyperosmotically induced activation of yeast GPD1.Homeostasis of intracellular inorganic ion concentrations and cell volume is essential for proper function of all cells. This is achieved by selective, energy-consuming electrolyte transport processes at the cell membrane (1) and by metabolic regulation of organic osmolyte levels in the cytoplasm (2). In situations of osmotic stress, cells adaptively osmoregulate by means of adjusting membrane water/ion fluxes and organic osmolyte levels. Such adaptive osmoregulation presumably is preceded by sensory and signaling events that monitor changes in osmotic strength and transduce this information to target genes and proteins of osmoprotective value.Recent work employing yeast genetics provides a wealth of information about the nature of osmosensing signal transduction in these primitive eukaryotic cells. The yeast Saccharomyces cerevisiae senses hyperosmolality through autophosphorylation of a sensor histidine kinase, SLN1, that is homologous to two-component sensor kinases common in bacteria (3). A second...

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Activation of heat-shock transcription factor 1 by hypertonic shock in 3T3 cells

Cited by 28 publications

References 39 publications

Dual regulation of a heat shock promoter during embryogenesis: stage‐dependent role of heat shock elements

Dual regulation of a heat shock promoter during embryogenesis: stage‐dependent role of heat shock elements

Cellular response to osmotic stress in the renal medulla

Distinct Regulation of Osmoprotective Genes in Yeast and Mammals

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