Tag Archives: store-operated Ca(2+) entry

Photoactivated fullerene C(60) induces store-operated Ca(2+) entry and cytochrome c release in Jurkat cells

S. M. Grebinyk1, K. O. Palyvoda2, S. V. Prylutska1, I. I. Grynyuk1,
A. A. Samoylenko2, L. B. Drobot2, O. P. Matyshevska1

1Taras Shevchenko Kyiv National University, Ukraine;
2Palladin Institute of Biochemistry, National Academy of Sciences of Ukraine, Kyiv;
e-mail: matysh@yahoo.com

The values of endoplasmic reticulum Ca2+-pool and store-operated Ca2+ entry (SOCE) were estimated in rat thymocytes and Jurkat cells loaded with indo-1 and treated with thapsigargin. It was shown that the relative value of SOCE in thymocytes was substantially lower than in Jurkat cells. Significant increase of SOCE in Jurkat cells preincubated with 10-5 M C60 and exposed to uv/visible light irradiation was detected at 1-3 h after exposure. At this time FCCP-induced Ca2+-release from mitochondria was shown to be reduced, while cytochrome c level into the cytoplasm of Jurkat cells, detected by Western blot analysis, to be increased. It is supposed that Ca2+ flux remodulation induced by photoexcited fullerene C60 in Jurkat cells might be involved in the initiation of signalling events leading to cell apoptosis.

IP(3)-sensitive Ca(2+)-channels of endoplasmic reticulum in secretory cells of the rat exorbital lacrimal gland

A. B. Kotliarova, V. V. Manko

Ivan Franko National University of Lviv, Ukraine;
e-mail: annkotliarova@gmail.com

The role of inositol-1,4,5-trisphosphate of (IP3)-sensitive Ca2+ channels in Ca2+ homeostasis maintenance under activation of M-cholinergic receptors and P2Y receptors in the secretory cells of the rat lacrimal gland was investigated. The study was carried out on intact and permeabilized secretory cells of exorbital lacrimal glands of rats. The cells were isolated using the modified Herzog, Sides, Miller method (1976) and permeabilized with digitonin (50 mg per 0.5 million cells). The functioning of the Ca2+-transport systems was estimated by changes of Ca2+ content in the studied cells, which was determined by the spectrophotometric method using arsenazo III. It was shown that IP3-sensitive Ca2+ channels (IP3Rs) of investigated cells are directly inhibited by 2-APB (10 µM/l). On the other hand, the channels are activated by IP3, cholinomimetic (carbacholine) and purine receptor agonist (ATP). When both M-cholinergic receptors and P2Y receptors were activated Ca2+ was released from the same IP3-sensitive store because the effects of ATP and carbacholine at high concentrations (1 mM/l and 10 µM/l, respectively) on the Ca2+ content were non-additive. The presence of the store-operated Ca2+-channels in secretory cells of the lacrimal gland is confirmed by the observed increase of cellular Ca2+ content as a result of Ca2+ mobilization from the store by carbacholine or thapsigargin and following restoration of Ca2+ concentration in the extracellular solution.