肌醇三磷酸（IP3）、蛋白激酶C（PKC）和细胞内pH值（pHi）在淡水蜗牛椎实螺（Lymnaea stagnalis）钙流蛋白刺激的蛋白腺刺激-反应偶联中的作用。

The role of IP3, PKC, and pHi in the stimulus-response coupling of calfluxin-stimulated albumen glands of the freshwater snail Lymnaea stagnalis.

作者信息

Dictus W J, Broers-Vendrig C M, de Jong-Brink M

机构信息

Department of Biology, Vrije Universiteit, Amsterdam, The Netherlands.

出版信息

Gen Comp Endocrinol. 1988 May;70(2):206-15. doi: 10.1016/0016-6480(88)90141-4.

DOI:10.1016/0016-6480(88)90141-4

PMID:2838378

Abstract

Signal-response coupling was studied in an exocrine female accessory sex gland (albumen gland) of the freshwater snail Lymnaea stagnalis. Glands were incubated in vitro with Calfluxin (CaFl), a neuropeptide which stimulates the influx of Ca2+ into the mitochondria of the secretory cells. This influx, which is considered to reflect an increase of Ca2+ in the cytosol, was measured as the percentage mitochondria containing Ca deposits. Ca deposits. Ca deposits were visualized at the ultrastructural level with the pyroantimonate precipitation technique. The origin of the Ca2+ and the mechanism by which the Ca2+ concentration in the cytosol is elevated were investigated. The results indicate that CaFl stimulates the influx of extracellular Ca2+ and mobilizes intracellular Ca2+. The increase of the percentage of mitochondria containing Ca deposits is sensitive to Ca2+ channel blockers (D600, Co2+, La3+), indicating that Ca2+ channels are involved. Li+ ions suppress the CaFl response, which suggests that the hydrolysis of phosphatidylinositol-4,5-bisphosphate (PIP2), and thus the production of myo-inositol-1,4,5-trisphosphate (IP3) and 1,2-diacylglycerol (DG) is involved in the Ca2+ mobilization. The protein kinase-C (PKC) stimulator 4-beta-phorbol 12-beta-myrastate 13-alpha-acetate (PMA) mimicked the response to CaFl. The PKC inhibitors trifluoperazine (TFP) and chlorpromazine (CP) markedly decreased the CaFl-stimulated influx of Ca2+ into the mitochondria. The PMA-stimulated influx of Ca2+ into the mitochondria is not dependent on extracellular Ca2+ and is not sensitive to Ca2+ channel blockers. In PMA-stimulated glands, the Na+/H+ exchange blocker amiloride completely abolished the Ca2+ influx into mitochondria. In CaFl-stimulated glands the influx was partly blocked. Increasing the internal pH of the glandular cells with the Na+/H+ ionophore monensin or with NH4Cl mimicked the CaFl response. It is proposed that upon stimulation with CaFl, mobilization of intracellular Ca2+ is mediated via the PKC-stimulated activation of the Na+/H+ exchange, thus leading to an increase of the internal pH. The role of IP3 in the mobilization of intracellular Ca2+ is uncertain.

摘要

在淡水螺椎实螺的雌性外分泌附属性腺（蛋白腺）中研究了信号 - 反应偶联。腺体在体外与钙流素（CaFl）一起孵育，钙流素是一种神经肽，可刺激Ca²⁺流入分泌细胞的线粒体。这种流入被认为反映了细胞质中Ca²⁺的增加，通过含有Ca沉积物的线粒体百分比来测量。用焦锑酸盐沉淀技术在超微结构水平上观察Ca沉积物。研究了Ca²⁺的来源以及细胞质中Ca²⁺浓度升高的机制。结果表明，CaFl刺激细胞外Ca²⁺的流入并动员细胞内Ca²⁺。含有Ca沉积物的线粒体百分比的增加对Ca²⁺通道阻滞剂（D600、Co²⁺、La³⁺）敏感，表明Ca²⁺通道参与其中。Li⁺离子抑制CaFl反应，这表明磷脂酰肌醇 - 4,5 - 二磷酸（PIP2）的水解，进而肌醇 - 1,4,5 - 三磷酸（IP3）和1,2 - 二酰基甘油（DG）的产生参与了Ca²⁺的动员。蛋白激酶C（PKC）刺激剂4 - β - 佛波醇12 - β - 肉豆蔻酸酯13 - α - 乙酸酯（PMA）模拟了对CaFl的反应。PKC抑制剂三氟拉嗪（TFP）和氯丙嗪（CP）显著降低了CaFl刺激的Ca²⁺流入线粒体。PMA刺激的Ca²⁺流入线粒体不依赖于细胞外Ca²⁺，并且对Ca²⁺通道阻滞剂不敏感。在PMA刺激的腺体中，Na⁺/H⁺交换阻滞剂阿米洛利完全消除了Ca²⁺流入线粒体。在CaFl刺激的腺体中，流入部分受阻。用Na⁺/H⁺离子载体莫能菌素或NH₄Cl增加腺细胞的内部pH模拟了CaFl反应。有人提出，在用CaFl刺激时，细胞内Ca²⁺的动员是通过PKC刺激的Na⁺/H⁺交换激活介导的，从而导致内部pH升高。IP3在细胞内Ca²⁺动员中的作用尚不确定。