Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.2.1.23 (beta-galactosidase)
 14,648 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Following heat shock the expression of heat shock genes is regulated by the heat shock transcription factor, HSF, known to bind to arrays of the heat shock element, NGAAN, upstream of the heat shock genes. Phosphorylation of HSF is necessary for its activation. We report that the treatment of Chinese hamster HA-1 cells with 250 nM of okadaic acid (OA), a ser/thr phosphatase inhibitor, leads to an increase in activated HSF after heat shock. This is followed by the activation of the transcription of heat shock genes as assayed by the increase in the synthesis of beta-galactosidase in an HA-1 cell line containing the heat shock promoter ligated to the beta-galactosidase gene. To investigate the specificity of OA, we used other phosphatase inhibitors. We found that treatment of HA-1 cells with 500 microM of sodium vanadate, an inhibitor of tyr/phosphatases, resulted in a three to fivefold reduction in HSF activation and binding to the heat shock element following heat shock. Such reduction in HSF activation virtually abolished beta-galactosidase induction. Reduced HSP synthesis was further confirmed by SDS-PAGE and Western blot analysis using anti-HSP-70 and 28 antibodies. Sodium vanadate treatment of heat shocked cells greatly reduced levels of thermotolerance. These results show that ser/thr and specifically tyr/phosphatase inhibitors modulate the signal transduction pathway of HSF activation.
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PMID:Inhibitors of tyrosine and Ser/Thr phosphatases modulate the heat shock response. 817 93

In normally growing Drosophila cultured cells the Drosophila heat shock transcription factor (dHSF) is localized in the cytosol and translocates into the nucleus after heat shock. In the cytosol of nonshocked cells, the dHSF is present as a monomer that cannot bind DNA. Upon stress, the dHSF enters the nucleus where it is observed to be a trimer. A novel nuclear localization sequence (NLS) in the dHSF was found to be responsible for stress-dependent nuclear entry. Deletion of the NLS prevents nuclear entry, as expected, yet surprisingly also allows constitutive oligomerization and DNA binding in the cytosol. Further analysis of the NLS by mutagenesis suggests that the two functions of nuclear entry and oligomerization are separable in that distinct residues present in the NLS are responsible for each. Mutations in certain basic residues completely block nuclear entry, as expected for a constitutive NLS. In addition, two residues were found in the NLS that, when altered, allowed constitutive nuclear entry of dHSF independent of stress. These residues may interact with a putative cellular component or possibly other domains of the HSF to prevent nuclear entry in normally growing cells. The NLS can also function autonomously to target a beta-galactosidase fusion protein into the nucleus in a heat shock-dependent fashion.
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PMID:Nuclear entry, oligomerization, and DNA binding of the Drosophila heat shock transcription factor are regulated by a unique nuclear localization sequence. 917 74

Evidence is provided for the presence at the physiological temperature of 20 degrees C of a heat shock transcriptor factor, HSF, in the nuclei of P.lividus embryos. This HSF is able to specifically bind in vitro the heat shock element, HSE, of the promoter of the hsp70 gene i.v., as suggested by DNA-protein binding reactions and DNAse I protection assays. Upon heat-shock, at the temperature of 31 degrees C, its ability to bind the HSE units becomes much higher. The HSF activated by heat-shock drives in vivo the transcription of the beta-galactosidase reporter gene in transgenic sea urchin gastrulae. An ATF-like transcription factor, widely described in other organisms but not at all in sea urchins, is also present in the nuclear extracts and is able to bind the consensus individuated in the hsp70 i.v. gene promoter.
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PMID:Sea urchin HSF activity in vitro and in transgenic embryos. 938 97

We examined the effects of cellular aging on the expression of the heat shock-inducible HSP70 gene in WI-38 diploid human fibroblasts serially passaged in vitro. The senescence of the cells was established by evaluating population doubling level, cell density at confluency, and cell morphology along with the detection of senescence-associated beta-galactosidase activity (histochemically detectable at pH 6), a reliable marker of aging in low-density cultures. A marked decrease in the synthesis and accumulation of the inducible HSP70 protein was observed in serum-fed late passage cells exposed to a severe heat shock (30 min at 45 degrees C) in comparison to early passage cells. However, the degree of HSF-DNA binding, monitored by gel retardation assay was similar in both early and late passage cells. Similarly, Northern blotting analysis indicated that comparable amounts of inducible HSP70 mRNA were present in the total RNA fraction, in the total polyadenylated RNA fraction, or in the nuclear polyadenylated RNA fraction extracted from both early and late passage cells. In contrast, much less inducible HSP70 mRNA was detected in the total cytoplasmic RNA fraction or in the polyadenylated cytoplasmic RNA fraction of late passage cells. Thus age-related differences in heat-induced HSP70 synthesis and accumulation observed in serum-fed WI-38 cells appeared to result from an impairment in the posttranscriptional processing of the HSP70 mRNA at a level following the polyadenylation step and preceding translocation from the nucleus to the cytoplasm. When HF were serum deprived for 20 h before heat shock, the induction of HSP70 mRNA was less than 30% reduced in early passage cells in comparison to serum-fed cells; however, the level of HSP70 mRNA was markedly (over 80%) decreased in serum-deprived late passage cells. This result indicated that the presence of serum has a strong influence on heat shock-induced HSP70 gene expression in human fibroblasts aging in vitro.
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PMID:Attenuated expression of 70-kDa heat shock protein in WI-38 human fibroblasts during aging in vitro. 1050 96

Schneider SL2 cells activate the myogenic program in response to the ectopic expression of daughterless alone, as indicated by exit from the cell cycle, syncytia formation, and the presence of muscle myosin fibrils. Myogenic conversion can be potentiated by the coexpression of DMEF2 and nautilus with daughterless. In RT-PCR assays Schneider cells express two mesodermal markers, nautilus and DMEF2 mRNAs, as well as very low levels of daughterless mRNA but no twist. Full-length RT-PCR products for nautilus and DMEF2 encode immunoprecipitable proteins. We used RNA-i to demonstrate that both endogenous nautilus expression and DMEF2 expression are required for the myogenic conversion of Schneider cells by daughterless. Coexpression of twist blocks conversion by daughterless but twist dsRNA has no effect. Our results indicate that Schneider cells are of mesodermal origin and that myogenic conversion with ectopic expression of daughterless occurs by raising the levels of daughterless protein sufficiently to allow the formation of nautilus/daughterless heterodimers. The effectiveness of RNA-i is dependent upon protein half-life. Genes encoding proteins with relatively short half-lives (10 h), such as nautilus or HSF, are efficiently silenced, whereas more stable proteins, such as cytoplasmic actin or beta-galactosidase, are less amenable to the application of RNA-i. These results support the conclusion that nautilus is a myogenic factor in Drosophila tissue culture cells with a functional role similar to that of vertebrate MyoD. This is discussed with regard to the in vivo functions of nautilus.
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PMID:RNA interference demonstrates a role for nautilus in the myogenic conversion of Schneider cells by daughterless. 1111 27

Tumor suppressor p53, hypoxia-inducible factor 1 (HIF-1) and heat-shock factor 1 (HSF-1) are involved as the key transcription factors in cellular response to stress, induced by genetic material damage, hypoxia and heat shock respectively. The protein factors listed above also play an integral part in tumor development and progression. Thus, modulation of their activity may be important for treatment of cancer. In our work we obtained the reporter constructs for quantitative assessment of p53, HIF-1 and HSF-1 transcriptional activity on the basis of retro- and lentiviruses, allowing to obtain reporter cell lines almost out of any cell type. Induction of beta-galactosidase reporter gene expression, reflecting the activity of p53 and HIF-1 factors, depends on dose of treatment and also correlates with the induction of the endogenous target genes expression. The observed effect of activating treatments completely disappeared when the expression of p53 and HIF-1 genes was inhibited with specific siRNAs. The obtained reporter constructs may find the application in the screening of chemical and genetic (such as siRNA- and cDNA-libraries) modulators of transcriptional activity along with the investigation of components of signal transduction pathways modulating the transcriptional activity of those factors.
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PMID:[Retroviral reporter systems for the assessment of activity of stress-induced signal transduction pathways controlled by p53, HIF-1 and HSF-1 transcription factors]. 1585 52