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Abstracts
THE POSSIBLE ROLE OF THE NON-GASTRIC H+/K+-ATPASE ATP12A (ATP1AL1) IN APOPTOSIS
Ritter, M. and Jakab, M.
Institute of Physiology and Pathophysiology, Paracelsus Medical University, Salzburg, Austria
The non-gastric H+/K+-ATPase ATP12A (ATP1AL1) is expressed in various tissues. We found by RTPCR and/or western blotting, intracellular pH measurements, electron microprobe analysis, cell volume (CV) measurements and flow cytometry that ATP12A is expressed in human myelomonocytic HL60 cells, rat insulinoma Ins-1E cells, human pancreatic islets, the prostate cancer cell lines LNCaP, PC3 and DU-145 as well as in normal and cancerous human prostate tissue. Treatment of HL60 cells with low (1mM) concentrations of butyrate leads to monocyte-directed differentiation whereas higher (510mM) concentrations induce apoptosis as assessed by flow cytometric determination of CD86 expression, CV, cell granularity, caspase activity, phosphatidylserine exposure on the outer cell membrane leaflet, cell cycle analysis
and cell proliferation. Ins-1E cells undergo apoptosis upon treatment with dexamethasone, the polyphenol resveratrol or by glucose starvationTranscriptional up-regulation of ATP12A is evident during apoptosis in HL60 and Ins-1E cells and both cell types exhibit apparent apoptotic volume decrease (AVD). The inhibitor of the H+/K+-ATPase SCH28080 leads per se to induction of apoptosis in HL60 cells and Ins-1E cells and accelerates the time course of induced apoptosis. Moreover ATP12A expression is altered in tissue from benign hyperplasia of human prostate and in prostate cancer. In summary it is shown that ATP12A is functionally active, plays a role during apoptosis in HL60 cells and Ins-1E cells and is differently expressed in normal and pathological prostate tissue.
THE INVOLVEMENT OF GLUTATHIONE SYSTEM IN THE REGULATION
OF THE FUNCTIONAL ACTIVITY OF NA+/K+-ATPASE PROTEINS IN OXIDATIVE STRESS
Ryazantseva, N.V., Stepovaya, Ye.A., Nosareva, O.L., Konovalova, Ye.V., Naumova, A.I., Shakhristova, Ye.V., Orlov, D.S., and Novitsky, V.V.
Siberian State Medical University, Tomsk, Russian Federation
The change in condition of glutathione system in oxi-dative stress is considered as one of the regulation mechanisms of cell volume. In formation of oxidative stress, the attack of active forms of oxygen is primarily directed not to the lipids, but the redox-sensitive amino acids in the proteins of cytosolic membranes. Therefore, the role of oxidative modification of proteins in disruption of plasmalemma can be put into the forefront. Glutathione and enzymatic redox-proteins of thiol-disulfide system associated with it ensure the process of S-thiolation/dethiolation of active protein nuclei, protecting them from irreversible oxidative modification and inacti-vation, which contributes to regulation of functional activity of the cells. It is known that the cell volume depends on functional activity of ion-transporting systems, including Na+/K+-ATPase. Providing catalytic functions and transitions between conformational states of Na+/K+-ATPase depends on lipid-protein interactions. A number
of molecular mechanisms of damage lead to oxidation of SH-groups of the enzyme.
The simulation of oxidative stress was carried out in blood lymphocytes by adding H202 into incubation medium at a final concentration of 5 mM; the concentration of hy-droxyl radical and protein-bound glutathione was estimated. It is shown that in incubating blood lymphocytes in the presence of 5 mM of H202, there occurred a fairly significant increase of the fraction of protein-bound glutathione (by 1.43 times) and hydroxyl radical (by 2.01 times), as compared with intact cells. In the formation of oxidative stress, the process of glutathionylation of cell proteins is being activated, and the activity of Na+/K+-ATPase increases, which contributes to maintaining the optimum lymphocyte volume for functioning.
The study was carried out with financial support within the framework of State Agreements No.8302 and No. 16.120.11.614-NS.
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Бюллетень сибирской медицины, 2013, том 12, № 4, с. 24-68
