3':5'-环磷酸腺苷和鸟嘌呤核苷酸对钙诱导的电通透AtT-20细胞促肾上腺皮质激素释放的影响。

Effects of adenosine 3':5'-cyclic monophosphate and guanine nucleotides on calcium-evoked ACTH release from electrically permeabilized AtT-20 cells.

作者信息

Guild S

机构信息

Department of Pharmacology, University of Glasgow.

出版信息

Br J Pharmacol. 1991 Sep;104(1):117-22. doi: 10.1111/j.1476-5381.1991.tb12394.x.

DOI:10.1111/j.1476-5381.1991.tb12394.x

PMID:1664757

原文链接:https://pmc.ncbi.nlm.nih.gov/articles/PMC1908274/

Abstract

The mouse AtT-20/D16-16 anterior pituitary tumour cell line was used as a model system for the investigation of adenosine 3':5'-cyclic monophosphate (cyclic AMP)-mediated enhancement of calcium-evoked adrenocorticotrophin (ACTH) secretion. 2. AtT-20 cells were permeabilized by subjecting the cells to intense electric fields. Exposure of permeabilized cells to calcium (1 mM) in the external medium significantly stimulated ACTH secretion over the first 20 min of exposure. This calcium-stimulated ACTH secretion was dependent upon the presence of MgATP (5 mM). 3. The amount of ACTH secreted, in a 20 min incubation at 37 degrees C, from permeabilized cells depended upon the free calcium concentration in the permeabilization medium. Calcium stimulated ACTH secretion from permeabilized cells in the concentration range of 10(-7)-10(-5) M (half maximal = 7 x 10(-7) M). Cyclic AMP(10(-4) M) increased the amount of ACTH secreted at each effective concentration of calcium. However, cyclic AMP did not alter the potency of calcium as a stimulant of ACTH secretion. 4. Guanosine 5'-O-(3-thiotriphosphate) (GTP-gamma-S, 10(-4) M) stimulated ACTH secretion from permeabilized cells in the absence of calcium and was additive with calcium-evoked ACTH secretion up to a maximum which could be stimulated by calcium acting singly. Guanosine 5'-O-(2-thiodiphosphate) (GDP-beta-S, 10(-4) M) inhibited calcium-evoked ACTH secretion from permeabilized cells. 5. GTP-gamma-S stimulated ACTH secretion from permeabilized cells in a concentration-dependent manner. The nucleotide significantly stimulated ACTH secretion at concentrations of 10-'M and above. Cyclic AMP (10-4 M) increased the amount of ACTH secretion evoked by effective concentrations of GTP-y-S.6. The results of the present study support the hypothesis that, in AtT-20 cells, cyclic AMP is acting at some site, distal to calcium entry, which modulates the ability of an increase in cytosolic calcium concentration to stimulate ACTH secretion. One such site may be a GTP-binding protein which the present study suggests may mediate the effects of calcium upon the secretory apparatus. These GTP-binding proteins may be a target for regulation by cyclic AMP.

摘要

小鼠AtT-20/D16-16垂体前叶肿瘤细胞系被用作一个模型系统，用于研究3':5'-环磷酸腺苷（环磷腺苷）介导的钙诱发促肾上腺皮质激素（ACTH）分泌增强作用。2. 通过对AtT-20细胞施加强电场使其透化。在外部培养基中，将透化细胞暴露于钙（1 mM）下，在暴露的前20分钟内显著刺激了ACTH分泌。这种钙刺激的ACTH分泌依赖于MgATP（5 mM）的存在。3. 在37℃孵育20分钟时，透化细胞分泌的ACTH量取决于透化培养基中的游离钙浓度。钙在10⁻⁷ - 10⁻⁵ M的浓度范围内刺激透化细胞分泌ACTH（半数最大效应浓度 = 7×10⁻⁷ M）。环磷腺苷（10⁻⁴ M）在每个有效的钙浓度下都增加了ACTH的分泌量。然而，环磷腺苷并没有改变钙作为ACTH分泌刺激物的效力。4. 5'-O-(3-硫代三磷酸)鸟苷（GTP-γ-S，10⁻⁴ M）在无钙的情况下刺激透化细胞分泌ACTH，并且与钙诱发的ACTH分泌相加，直至达到单独钙刺激所能达到的最大值。5'-O-(2-硫代二磷酸)鸟苷（GDP-β-S，10⁻⁴ M）抑制透化细胞的钙诱发ACTH分泌。5. GTP-γ-S以浓度依赖的方式刺激透化细胞分泌ACTH。该核苷酸在10⁻⁶ M及以上的浓度下显著刺激ACTH分泌。环磷腺苷（10⁻⁴ M）增加了有效浓度的GTP-γ-S诱发的ACTH分泌量。6. 本研究结果支持以下假设：在AtT-20细胞中，环磷腺苷在钙进入细胞的远端某个位点起作用，调节细胞质钙浓度增加刺激ACTH分泌的能力。一个这样的位点可能是一种GTP结合蛋白，本研究表明它可能介导钙对分泌装置的作用。这些GTP结合蛋白可能是环磷腺苷调节的靶点。