2001 Fiscal Year Final Research Report Summary
study on Ca2+ influx by Methpds of Cell Biology in Mouse Fggs
| Project/Area Number |
12680706
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Cell biology
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| Research Institution | Natiomal Institute for Physiological Scienes |
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Principal Investigator |
MOHRI Tatsuma Natiomal Institute for Physiological Scienes Research Associate, 生理学研究所, 助手 (60290912)
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| Project Period (FY) |
2000 – 2001
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| Keywords | Ca^<2+> oscillations / Ca^<2+> influx / Ca^<2+> measurement / Mn^<2+> quenching / SE(sperm extract) / Insp3(inositol 1,4,5trisphosphate) / InsP_3R(InsP_3receptors) / capacitativeCa^<2+>influx |
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| Research Abstract |
Our objective of the study was to investigate the mechanisms of Ca^2+ influx as an universal phenomenon in cell biology. To elucidate the intracellular or extracellular Ca^2+ mobilization during Ca^2+ oscillations in the cell system we investigated the spatio-temporal pattern of intracellular Ca^2+ and Ca^2+ influx in mouse eggs using cell-biological techniques that are intacellular Ca^2+ imaging, Mn^2+ quench of fluorescence dye, Fura-2 and microinjection of stimulants or an antibody, which is a functional inhibitor of activation. Ca^2+ oscillations were induced by microinjection of hamster sperm extract (SE) into mouse eggs. We found the following 4 points, l) Competitive Mn^2+/Ca^2+ influx exists at the resting state. A marked Mn^2+/Ga^2+ influx occurs during the first Ca^2+ release upon SE iniection. and persistently facilitated Mn^2+/Ca^2+ influx is observed during steady Ca^2+ oscillations. As intracellular Mn^2+ concentration ([Mn^2+]i) increased progressively, periodic [Mn^2+] rises appear, corresponding to each Ca^2+ transient but taking a slower time course. A numerical simulation and Mn^2+ oscillations calculated from experimental data strongly suggest that repetitive Mn^2+ release develops after Mn2+ entry and uptake into the ER. 2) No significant increase in Mn^2+influx was detected by injection of SE, InsP_3, or Ca^2+, when Ca^2+ release was prevented by pre-injection of an antibody against the InsP_3 receptor, suggesting that none of them itself causes Ca2+ influx. 3) Depletion of the ER using an ER Ca^2+ pump inhibitor, thapsigargin plus repetitive injection of inositol 1, 4, 5-trisphosphate (InsP_3) cause a marked Mn2+ influx, suggesting that mouse eggs have a cpacitative mechanism. 4) Ca^2+ influx is activated during the initial large Ca^2+ release possibly by a capacitative mechanism and kept facilitated during steady Ca^2+ oscillations.
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[Publications] Mohri. T.. Shirakawa, H., Oda, S., Sato, M. S., Mikoshiba, K., and Miyazaki, S: "Ca^2+/Mn^2+ dynamics during Ca^2+ oscillations induced by microinjection of sperm extract in mouse eggs."Cell Struct Funct. 6, Suppl. 568 (2000)
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