• Biomolecules & Therapeutics
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• v.31 no.1
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• pp.59-67
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• 2023

Thrombin is a serine protease that participates in a variety of biological signaling through protease-activated receptors. Intestinal myofibroblasts play central roles in maintaining intestinal homeostasis. In this study, we found that thrombin-induced apoptosis is mediated by the calcium-mediated activation of cytosolic phospholipase A₂ in the CCD-18Co cell. Thrombin reduced cell viability by inducing apoptosis and proteinase-activated receptor-1 antagonist attenuated thrombin-induced cell death. Endogenous ceramide did not affect the cell viability itself, but a ceramide-mediated pathway was involved in thrombin-induced cell death. Thrombin increased intracellular calcium levels and cytosolic phospholipase A₂ activity. The ceramide synthase inhibitor Fumonisin B1, intracellular calcium chelator BAPTA-AM, and cytosolic phospholipase A₂ inhibitor AACOCF₃ inhibited thrombin-induced cell death. Thrombin stimulated arachidonic acid release and reactive oxygen species generation, which was blocked by AACOCF₃, BAPTA-AM, and the antioxidant reagent Trolox. Taken together, thrombin triggered apoptosis through calcium-mediated activation of cytosolic phospholipase A₂ in intestinal myofibroblasts.

• Toxicological Research
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• v.16 no.4
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• pp.311-315
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• 2000

Previous studies showed that benzoquinone derivatives inhibited platelet aggregation. but there is no information available on their cytotoxicity to platelets. 1n the present study. washed platelets isolated from rats were treated with 1.4-benzoquinone. a representative benzoquinone derivative. to examine its antiaggregating effect and cytotoxicity. 1.4-Benzoquinone significantly inhibited thrombin-induced platelet aggregation. Consistent with this finding. 1.4-benzoquinone suppressed cytosolic calcium increase induced by thrombin. To examine the cytotoxicity by 1 A-benzoquinone in platelets. turbidometry and lactate dehydrogenase release were measured. Treatment with 1.4-benzoquinone resulted in slight cytotoxicity (30% release at 60 min) to platelets. However. the cytotoxicity was not correlated with increase of cytosolic calcium levels in platelets. All these data suggested that 1.4-benzoquinone inhibited thrombin-induced platelet aggregation mediated by inhibition elf calcium level increase and that 1.4-benzoquinone reveals cytotoxicity to some extent without alteration of calcium level in platelets.

• Journal of Plant Biology
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• v.34 no.3
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• pp.239-244
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• 1991

Ca2+ is implicated as a second messenger in coupling various stimuli such as hormone, gravity and light. The determine whether or not plant hormones mobilize calcium with different action, we investigated the cytosolic Ca2+ changes by IAA and zeatin in the protoplasts isolated from elongating mesocotyl of maize. IAA increased the influx of Ca2+ due to the calcium channel opening, which was confirmed by using verapamil, calcium channel blocker. On the other hand, zeatin increased the cytosolic Ca2+ by promoting the efflux of Ca2+ derived from cellular organelles. These results suggest that different calcium flux induced by IAA and zeatin plays a role in appropriate response resulting in increase of cell elongation or repression cell elongatoin.

• Journal of Ginseng Research
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• v.20 no.2
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• pp.159-167
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• 1996

To study the effects of ginseng saponin components on the signal transduction in the ac tivation of murine macrophages, phagocytosis and Intracellular calcium concentration of peritoneal exuded mouse macrophages were examined. The phagocytosis was increased significantly after treatment with total saponin, diol-saponin, $Rg_1$ and $Rg_2$, but triol-saponin was unable to increase phagocytosis. The phagocytosis were increased when H7, a PKC inhibitor, was pretreated and increased significantly by saponin fractions except total saponin. Pertussis toxin, which inactivates G-protein, decreased the phagocytosis. But the phagocytosis was restored to the control level by saponin fractions and the phagocytosis was increased significantly by $Rg_2$ and $Rg_2$. The triol saponin increased phagocytosis approximately by 2-fold as compared with the TMB-8 treated group. Peritoneal exuded macrophages displayed a prominent rise in cytosolic calcium following treatment with triol-saponin, $Rg_1$, $Rg_2$ and $Rg_2$. Incubation of macrophages with PT resulted in an inhibition of cytosolic calcium mobilization, but increased cytosolic calcium mobilization with saponin fraction.

• Toxicological Research
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• v.14 no.4
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• pp.507-513
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• 1998

The purpose of this study was to clarify the effect of silica on cytosolic free calcium mobilization and cell injury in primary cultured rat hepatocytes. Cytosolic free calcium concentration ([Ca$^{2+}$]) was measured employing calcium sensitive fluorescent dye, Fura-2 / AM, and cell injury was evaluated by determination of cellular ATP contents. Silica increased [Ca$^{2+}$], in a concentration-dependent manner in hepatocytes (10$^{-5}$ ~10$^{-2}$ M). Silica caused a biphasic increase in [Ca$^{2+}$], which was composed of an initial rapid rise and following sustained phase. $Ca^{2+}$ removal from the medium resulted in abolishment of initial and sustained phase of silica (10$^{-2}$ M)-induced [Ca$^{2+}$], in hepatocytes. The pretreatment with nifedipine (1 $\mu$M) attenuated silica-induced [Ca$^{2+}$], increases. Silica decreased cellular ATP contents in a dose-dependent manner. This silica-induced cell injury was attenuated by the pretreatment with EGTA (100 $\mu$M) and nifedipine (1 $\mu$M). This study suggests that the elevation of [Ca$^{2+}$], caused by silica may be due mainly to influx through a plasma membrane $Ca^{2+}$ channel and hepatotoxicity by silica relate with alteration of calcium homeostasis.ium homeostasis.

• The Korean Journal of Physiology and Pharmacology
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• v.2 no.4
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• pp.419-425
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• 1998

To clarify the effect of extracellular ATP in cultured C6 glioma cells, ATP-induced cytosolic free calcium ($[Ca^{2+}]_i$) mobilization and cell proliferation were investigated. ATP-induced $[Ca^{2+}]_i$ increased in a dose-dependent manner $(10^{-7}\;M{\sim}10^{-3}\;M)$. ATP-induced $[Ca^{2+}]_i$ increases were slightly slowed in extracellular calcium-free conditions especially in sustained phase. ATP-induced $[Ca^{2+}]_i$ increment was also inhibited by the pretreatment of U73122, a phospholipase C (PLC) inhibitor, in a time-dependent manner. Suramin, a putative $P_{2Y}$ receptor antagonist, dose-dependently weakened ATP-induced $[Ca^{2+}]_i$ mobilization. Significant increases in cell proliferation were observed at 2, 3, and 4 days after ATP was added. Stimulated cell proliferation was also observed with adenosine at days 2 and 3. This cell proliferation was significantly inhibited by the treatment with suramin. Ionomycin also stimulated cell proliferation in a concentration-dependent manner. In conclusion, we suggest that extracellular ATP stimulates C6 glioma cell proliferation via intracellular free calcium mobilization mediated by purinoceptor.

• Proceedings of the Zoological Society Korea Conference
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• 1995.10b
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• pp.293.2-293
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• 1995

No Abstract, See Full Text

• BMB Reports
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• v.56 no.3
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• pp.172-177
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• 2023

BEST family is a class of Ca²⁺-activated Cl- channels evolutionary well conserved from bacteria to human. The human BEST paralogs (BEST1-BEST4) share significant amino acid sequence homology in the N-terminal region, which forms the transmembrane helicases and contains the direct calcium-binding site, Ca²⁺-clasp. But the cytosolic C-terminal region is less conserved in the paralogs. Interestingly, this domain-specific sequence conservation is also found in the BEST1 orthologs. However, the functional role of the C-terminal region in the BEST channels is still poorly understood. Thus, we aimed to understand the functional role of the C-terminal region in the human and mouse BEST1 channels by using electrophysiological recordings. We found that the calcium-dependent activation of BEST1 channels can be modulated by the C-terminal region. The C-terminal deletion hBEST1 reduced the Ca²⁺-dependent current activation and the hBEST1-mBEST1 chimera showed a significantly reduced calcium sensitivity to hBEST1 in the HEK293 cells. And the C-terminal domain could regulate cellular expression and plasma membrane targeting of BEST1 channels. Our results can provide a basis for understanding the C-terminal roles in the structure-function of BEST family proteins.

• Journal of applied mathematics & informatics
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• v.29 no.1_2
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• pp.427-442
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• 2011

Calcium is a vital second messenger for signal transduction in neurons. Calcium plays an important role in almost every part of the human body but in neuronal cytosol, it is of utmost importance. In order to understand the calcium signaling mechanism in a better way a finite element model has been developed to study the flow of calcium in two dimensions with time. This model assumes EBA (Excess Buffering Approximation), incorporating all the important parameters like time, association rate, influx, buffer concentration, diffusion constant etc. Finite element method is used to obtain calcium concentration in two dimensions and numerical integration is used to compute effect of time over 2-D Calcium profile. Comparative study of calcium signaling in two dimensions with time is done with other important physiological parameters. A MATLAB program has been developed for the entire problem and simulated on an x64 machine to compute the numerical results.

• Journal of Acupuncture Research
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• v.21 no.5
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• pp.179-190
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• 2004

Objectives : The purpose of this study was to investigate the effect of Bee Venom and Melittin acupuncture solution on the lipopolysaccharide and sodium nitroprusside- induced expression of cytosolic phospholipase $A_2$, tumor necrosis factor-${\alpha}$ and calcium concentration in RAW 264.7 cells, a murine macrophage cell line. Methods : The expression of cytosolic phospholipase $A_2$ and tumor necrosis factor-${\alpha}$ was determined by western blotting with corresponding antibodies, and the generation of intracellular calcium concentration was investigated by delta scan system in RAW 264.7 cells. Results : 1. Compared with control, expressions of lipopolysaccharide-induced cytosolic phospholipase $A_2$ were decreased significantly by $5{\mu}g/mL$ of bee venom and 5, $10{\mu}g/mL$ of melittin acupuncture solution and decreased by 0.5, $1{\mu}g/mL$ of bee venom. 2. Compared with control, expressions of sodium nitroprusside-induced phospholipase $A_2$ were decreased significantly by 0.5, 1, $5{\mu}g/mL$ of bee venom and by 5, $10{\mu}g/mL$ of melittin acupuncture solution. 3. Compared with control, expressions of lipopolysaccharide-induced tumor necrosis factor-${\alpha}$ were decreased significantly by $10{\mu}g/mL$ of melittin acupuncture solution and were not changed significantly by 0.5, 1, $5{\mu}g/mL$ of bee venom and $5{\mu}g/mL$ of melittin acupuncture solution. 4. Compared with control, expressions of sodium nitroprusside-induced tumor necrosis factor-${\alpha}$ were decreased significantly by 1, $5{\mu}g/mL$ of bee venom and 5, $10{\mu}g/mL$ of melittin acupuncture solution and decreased by $0.5{\mu}g/mL$ of bee venom 5. Compared with control, lipopolysaccharide-induced intracellular calcium concentrations were decreased by 0.5, 1, $5{\mu}g/mL$ of bee venom and $10{\mu}g/mL$ of melittin acupuncture solution and increased by $5{\mu}g/mL$ of melittin acupuncture solution. 6. Compared with control, sodium nitroprusside-induced intracellular calcium concentrations were decreased by 0.5, 1, $5{\mu}g/mL$ of bee venom and 5, $10{\mu}g/mL$ of melittin acupuncture solution.