Dependence of insulin secretion from permeabilized pancreatic β-cells on the activation of Ca2+/calmodulin-dependent protein kinase II -: A re-evaluation of inhibitor studies
Dependence of insulin secretion from permeabilized pancreatic β-cells on the activation of Ca2+/calmodulin-dependent protein kinase II -: A re-evaluation of inhibitor studies
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DOI：
10.1016/s0006-2952(00)00483-4
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发表时间：
2000-12-01
影响因子：
5.8
通讯作者：
Easom, RA
中科院分区：
文献类型：
--
作者：
Bhatt, HS;Conner, BP;Easom, RA
以前的研究利用钙/钙调蛋白依赖性蛋白激酶II（CaM激酶II）的抑制剂，以解决这种酶在胰岛素分泌中的作用，产生了矛盾的结果。在当前的研究中，这些不一致性已经通过评价各种CaM激酶II抑制剂降低Ca 2+诱导的透化β细胞胰岛素分泌的作用来解决。KN-93（2-[N-（2-羟乙基）-N-（反式-甲氧基-苯磺酰基）]-氨基-N-（4-氯肉桂酰基）-N-甲基苄胺）在α-毒素透化的β-细胞中平行地显著抑制CaM激酶II活化和胰岛素分泌。这些效应是特异性的，因为它们不被无活性类似物KN-92（2-[N-（4-甲氧基苯磺酰基）]-氨基-N-（4-氯肉桂基）-N-甲基苄胺）模拟。相反，KN-62（1-[N，O-双（5-异喹啉磺酰基）-N-甲基-1-酪氨酰基]-4-苯基哌嗪），虽然据报道在作用机制方面与KN-93相似，但在这些细胞制剂中不抑制Ca 2+诱导的CaM激酶II活化或胰岛素分泌。所有三种药物都抑制了在存在升高的细胞外钾的情况下由去极化诱导的完整β细胞中的Ca 2+内流，尽管程度不同。CaM激酶II的合成肽抑制剂[Ala（286）]CaMK 281-302和AIP（autocamtide-2-related inhibitory peptide）强烈抑制Ca 2+诱导的电透化胰岛的胰岛素分泌，这种作用也与CaM激酶II激活的等效抑制相关。该重新评估（i）基于KN-62不能抑制这些制剂中CaM激酶II的活化，解释了KN-62对透化细胞的胰岛素分泌缺乏作用;（ii）已经揭示了CaM抑制剂，无论是化学的还是肽的性质，其能够防止酶活化均匀地抑制Ca 2+敏感的胰岛素分泌;和（iii）在完整细胞研究中，谨慎使用KN-62/93/92作为CaM激酶II的选择性抑制剂。这些观察结果加强了CaM激酶II在β细胞中胰岛素胞吐中起重要作用的建议。(C)2000 Elsevier Science Inc.
Previous studies utilizing inhibitors of the Ca2+/calmodulin-dependent protein kinase II (CaM kinase II) to address the role of this enzyme in insulin secretion have produced contradictory results. In the current study, these inconsistencies have been addressed by evaluating the effect of various CaM kinase II inhibitors to decrease Ca2+-induced insulin secretion from permeabilized beta -cells. KN-93 (2-[N-(2-hydroxyethyl)-N-(dr-methoxy-benzenesulfonyl)]-amino-N-(4-chlorocinnamyl)-N-methylbenzylamine) markedly inhibited both CaM kinase II activation and insulin secretion in parallel in alpha -toxin-permeabilized beta -cells. These effects were specific since they were not mimicked by the inactive analog, KN-92 (2-[N-(4-methoxybenzenesulfonyl)]-amino-N-(4-chlorocinnamyl)-N-methylbenzylamine). In contrast, KN-62 (1-[N,O-bis(5-isoquinolinesulfonyl)-N-methyl-1-tyrosyl]-4-phenylpiperazine), while reported to be similar to KN-93 with respect to mechanism of action, did not inhibit Ca2+-induced activation of CaM kinase II or insulin secretion in these cell preparations. All three agents suppressed Ca2+ influx in intact beta -cells induced by depolarization in the presence of elevated extracellular potassium although to different extents. The synthetic peptide inhibitors of CaM kinase II, [Ala(286)]CaMK 281-302 and AIP (autocamtide-2-related inhibitory peptide), strongly inhibited Ca2+-induced insulin secretion from electropermeabilized islets, an effect that also correlated with an equivalent inhibition of CaM kinase II activation. This re-evaluation (i) explains a lack of effect of KN-62 on insulin secretion from permeabilized cells based on its inability to inhibit CaM kinase II activation in these preparations; (ii) has revealed that CaM inhibitors, either chemical or peptide in nature, that are capable of preventing enzyme activation uniformly suppress Ca2+-sensitive insulin secretion; and (iii) cautions the use of KN-62/93/92 as selective inhibitors of CaM kinase II in intact cell studies. These observations reinforce the suggestion that CaM kinase II plays an important role in insulin exocytosis in the beta -cell. (C) 2000 Elsevier Science Inc.