Vitamin D3 analogs stimulate calcium currents in rat osteosarcoma cells.
Vitamin D3 analogs stimulate calcium currents in rat osteosarcoma cells.
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DOI：
10.1016/s0021-9258(19)51022-5
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发表时间：
1994-09
期刊：
影响因子：
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通讯作者：
S. Yukihiro;G. Posner;S. Guggino
中科院分区：
文献类型：
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作者：
S. Yukihiro;G. Posner;S. Guggino
1 α，25-二羟基维生素D3（1，25-D3）迅速（在几秒钟内）将内向钙电流激活的阈值转移到更负的生理电位。为了确定骨细胞中钙通道的开放是否由胞质1，25-二羟基维生素D3受体（VDR）、几种天然代谢物1，25-D3、25-羟基维生素D3和24 R、25-二羟基维生素D3以及合成类似物25-羟基-16，23 E-二烯D3（HO）、25-羟基-23-炔D3（Y）和1 α介导，25-二羟基-16-烯-23-炔-26，27-F6 D3（EO）对二氢吡啶敏感的内向钡电流进行了测试。为了探测类固醇1位刺激钡电流的结构特异性，我们使用了几种合成的1-（1 '-羟乙基）（NP、ON、NN、OP）和1-（2'-羟乙基）-25-羟基维生素D3类似物（14 w-1 α和14-w 1 β）。使用穿孔膜片钳技术，我们发现天然存在的维生素D3类似物对钡电流的刺激的等级顺序效力与它们对VDR的亲和力几乎相同，其中1，25-D3是最有效的类似物。使用对VDR具有最小亲和力的合成类似物，我们发现没有1-OH基团但在位置16和23处具有额外双键或在位置23处具有三键的化合物保留了对钙通道活化的高亲和力。此外，在1'位的1-羟乙基-25-羟基维生素D3 R异构体比在该位置的S异构体具有更大的亲和力，并且β取向的2'-羟乙基基团给予同系物比α取向的2 '-羟乙基基团更大的亲和力。这些合成类似物对钙通道产生快速作用，并显示出与细胞溶质维生素D3受体结合不同的药理学特异性，这一事实表明钙内流是由不同的信号转导途径介导的。1，25-D3（50 pM）的高生理亲和力表明它是钙通道的生物调节剂。
1 alpha, 25-Dihydroxyvitamin D3 (1,25-D3) rapidly (within seconds) shifts the threshold for activation of inward calcium currents to more negative and physiological potentials. To determine whether the opening of calcium channels in bone cells is mediated by the cytosolic 1,25-dihydroxyvitamin D3 receptor (VDR), several natural metabolites 1,25-D3, 25-hydroxyvitamin D3, and 24R,25-dihydroxyvitamin D3 and synthetic analogs 25-hydroxy-16,23E-diene D3 (HO), 25-hydroxy-23-yne D3 (Y), and 1 alpha, 25-dihydroxy-16-ene-23-yne-26,27-F6 D3 (EO) were tested on dihydropyridine-sensitive inward barium currents. In order to probe the structural specificity at the 1 position of the steroid for stimulation of barium currents, we used several synthetic 1-(1'-hydroxyethyl) (NP, ON, NN, OP) and 1-(2'-hydroxyethyl)-25-hydroxyvitamin D3 analogs (14w-1 alpha and 14-w1 beta). Using the perforated patch-clamp technique, we found that the naturally occurring vitamin D3 analogs gave nearly the same rank order potency for stimulation of barium currents as their affinity for VDR with 1,25-D3 being the most potent analog. Using the synthetic analogs which have minimal affinity for VDR, we found that the compounds without 1-OH group but with additional double bonds in positions 16 and 23 or with a triple bond in position 23 retained high affinity for calcium channel activation. Furthermore, 1-hydroxyethyl-25-hydroxyvitamin D3R isomers at the 1' position had greater affinity than the S isomers at this position, and a beta oriented 2'-hydroxyethyl group gave the homolog greater affinity than did the alpha-oriented 2'-hydroxyethyl group. The fact that these synthetic analogs cause rapid effects on calcium channels and show pharmacological specificity different from the binding to the cytosolic vitamin D3 receptor suggests that calcium influx is mediated by a distinct signal transduction pathway. The high and physiological affinity of 1,25-D3 (50 pM) suggests that it is a biological regulator of calcium channels.