Phosphorylation of A 27-kDa protein correlates with survival of protein-synthesis-inhibited MCF-7 cells

Impact of Non-Invasive Physical Plasma on Heat Shock Protein Functionality in Eukaryotic Cells

Recently, biomedical research has increasingly investigated physical plasma as an innovative therapeutic approach with a number of therapeutic biomedical effects. It is known from radiation and chemotherapy that these applications can lead to the induction and activation of primarily cytoprotective heat shock proteins (HSP). HSP protect cells and tissues from physical, (bio)chemical, and physiological stress and, ultimately, along with other mechanisms, govern resistance and treatment failure. These mechanisms are well known and comparatively well studied in drug therapy. For therapies in the field of physical plasma medicine, however, extremely little data are available to date. In this review article, we provide an overview of the current studies on the interaction of physical plasma with the cellular HSP system.

Interaction of aurintricarboxylic acid (ATA) with four nucleic acid binding proteins DNase I, RNase A, reverse transcriptase and Taq polymerase

In the investigation of interaction of aurintricarboxylic acid (ATA) with four biologically important proteins we observed inhibition of enzymatic activity of DNase I, RNase A, M-MLV reverse transcriptase and Taq polymerase by ATA in vitro assay. As the telomerase reverse transcriptase (TERT) is the main catalytic subunit of telomerase holoenzyme, we also monitored effect of ATA on telomerase activity in vivo and observed dose-dependent inhibition of telomerase activity in Chinese hamster V79 cells treated with ATA. Direct association of ATA with DNase I (K(d)=9.019 microM)), RNase A (K(d)=2.33 microM) reverse transcriptase (K(d)=0.255 microM) and Taq polymerase (K(d)=81.97 microM) was further shown by tryptophan fluorescence quenching studies. Such association altered the three-dimensional conformation of DNase I, RNase A and Taq polymerase as detected by circular dichroism. We propose ATA inhibits enzymatic activity of the four proteins through interfering with DNA or RNA binding to the respective proteins either competitively or allosterically, i.e. by perturbing three-dimensional structure of enzymes.

Impaired migration of trophoblast cells caused by simvastatin is associated with decreased membrane IGF-I receptor, MMP2 activity and HSP27 expression

BACKGROUND

Statins inhibit 3-hydroxy-3-methylglutaryl coenzyme-A reductase, the rate-limiting enzyme of the mevalonate pathway, and are used successfully in the treatment of hypercholesterolaemia. Statins are contraindicated during pregnancy. Lately, we have shown that simvastatin has adverse affects on human first trimester placental explants' proliferation and migration. The objective of the present study was to investigate the molecules involved in mediating simvastatin's effect on trophoblast cell migration. We hypothesized that simvastatin attenuates insuline-like growth factor-I (IGF-I) receptor expression (involved in trophoblast motility), matrix metalloproteinase (MMP) activities, and heat shock protein 27 (HSP27) levels (whose mRNA is actively transcribed during trophoblast differentiation) in trophoblast cells thus consequently effecting their migration.

METHODS

Human placental explants were cultured above a matrigel with/without simvastatin (10 microM) for 5 days. In this model, trophoblast migrates from the villi into the matrigel. Western-blot and immunohistochemistry served for analysing HSP27 expression. Immunohistochemistry was used for assessing IGF-I receptor localization. MMPs activity was assayed by gel zymography.

RESULTS

Simvastatin reduced IGF-I receptor membranal expression, MMP2 activity and HSP27 expression in trophoblast cells (P < 0.05).

CONCLUSIONS

The inhibitory effect of simvastatin on trophoblast cell migration is associated with a significant decrease in the tested molecules, which probably contributes to the impaired migration.

Proteomic analysis of calcium/calmodulin-dependent protein kinase I and IV in vitro substrates reveals distinct catalytic preferences

The multifunctional calcium/calmodulin-dependent protein kinases I and IV (CaMKI and CaMKIV) are closely related by primary sequence and predicted to have similar substrate specificities based on peptide studies. We identified a fragment of p300-(1-117) that is a substrate of both kinases, and through both mutagenesis and Edman phosphate ((32)P) release sequencing, established that CaMKI and CaMKIV phosphorylate completely different sites. The CaMKI site, Ser(89) ((84)LLRSGSSPNL(93)), fits the expected consensus whereas the CaMKIV site, Ser(24) ((19)SSPALSASAS(28)), is novel. To compare kinase substrate preferences more generally, we employed a proteomic display technique that allowed comparison of complex cell extracts phosphorylated by each kinase in a rapid in vitro assay, thereby demonstrating substrate preferences that overlapped but were clearly distinct. To validate this approach, one of the proteins labeled in this assay was identified by microsequencing as HSP25, purified as a recombinant protein, and examined as a substrate for both CaMKI and CaMKIV. Again, CaMKI and CaMKIV were different, this time in kinetics and stoichiometry of the phosphorylation sites, with CaMKI preferring Ser(15) ((10)LLRTPSWGPF(19)) to Ser(85) ((80)LNRQLSSGVS(89)) 3:1, but CaMKIV phosphorylating the two sites equally. These differences in substrate specificities emphasize the need to consider these protein kinases independently despite their close homology.

Heat shock proteins in human cancer

The heat shock proteins (hsp) are ubiquitous molecules induced in cells exposed to sublethal heat shock, present in all living cells, and highly conserved during evolution. Their function is to protect cells from environmental stress damage by binding to partially denatured proteins, dissociating protein aggregates, to regulate the correct folding, and to cooperate in transporting newly synthesized polypeptides to the target organelles. The molecular chaperones are involved in numerous diseases, including cancer, revealing changes of expression. In this review, we mainly describe the relationship of hsp expression with human cancer, and discuss what is known about their post-translational modifications according to malignancies.

Aurintricarboxylic acid inhibits apoptosis and supports proliferation in a haemopoietic growth-factor dependent myeloid cell line

The actions of the nuclease inhibitor aurintricarboxylic acid (ATA) were investigated in the growth-factor dependent murine myeloid cell line NSF-60. NSF-60 cells proliferate in response to interleukin-3 (IL-3) and undergo apoptosis when deprived of exogenous IL-3, as demonstrated by the appearance of characteristic DNA 'ladders' following agarose gel electrophoresis. ATA, at concentrations between 5 and 25 microM, inhibited apoptosis in growth-factor deprived cells as demonstrated by inhibition of DNA fragmentation and increased cell survival. ATA at a concentration of 25 microM supported proliferation of the cell line in the absence of exogenous growth-factor. Both ATA and IL-3 increased protein phosphorylation in this cell line. ATA and IL-3 induced proliferation was inhibited by the kinase inhibitors genistein, staurosporine and H-7. These findings suggest that, in NSF-60, ATA is not acting exclusively as an endonuclease inhibitor and that protein phosphorylation is involved in the mechanism of action of ATA in this cell line.