确定I型肌醇1,4,5-三磷酸受体部分激动作用的最小结构要求。

Defining the minimal structural requirements for partial agonism at the type I myo-inositol 1,4,5-trisphosphate receptor.

作者信息

Wilcox R A, Fauq A, Kozikowski A P, Nahorski S R

机构信息

Department of Cell Physiology and Pharmacology, University of Leicester, UK.

出版信息

FEBS Lett. 1997 Feb 3;402(2-3):241-5. doi: 10.1016/s0014-5793(96)01540-2.

DOI:10.1016/s0014-5793(96)01540-2

PMID:9037203

Abstract

The novel synthetic analogues D-3-fluoro-myo-inositol 1,5-bisphosphate-4-phosphorothioate, [3F-Ins(1,5)P2-4PS], D-3-fluoro-myo-inositol 1,4-bisphosphate-5-phosphorothioate [3F-Ins(1,4)P2-5PS], and D-3-fluoro-myo-inositol 1-phosphate-4,5-bisphosphorothioate [3F-Ins(1)P-(4,5)PS2] were utilised to define the structure-activity relationships which could produce partial agonism at the Ca2+ mobilising myo-inositol 1,4,5-trisphosphate [Ins(1,4,5)P3] receptor. Based on prior structure-activity data we hypothesised that the minimal structural requirements for lns(1,4,5)P3 receptor partial agonism, were phosphorothioate substitution of the crucial vicinal 4,5-bisphosphate pair accompanied by another structural perturbation, such fluorination of 3-position of the myo-inositol ring. All the analogues fully displaced [3H]Ins(1,4,5)P3 from a single Ins(1,4,5)P3 binding site in pig cerebellar membranes [3F-Ins(1,5)P2-4PS (1C50 = 26 nM), 3F-Ins(1,4)P2-5PS (IC50 = 80 nM) and 3F-Ins(1)P-(4,5)PS2 (IC50 = 109 nM) cf. Ins(1,4,5)P3 (IC50 = 11 nM)]. In contrast, 3F-Ins(1,5)P2-4PS (IC50 = 424 nM) and 3F-Ins(1,4)P2-5PS (IC50 = 3579 nM) were weak full agonists at the Ca2+ mobilising Ins(1,4,5)P3 receptor of permeabilised SH-SY5Y neuroblastoma cells, being respectively 4- and 36-fold less potent than Ins(1,4,5)P3 (EC50 = 99 nM). While 3F-Ins(1)P-(4,5)PS2 (EC50 = 11345 nM) was a partial agonist releasing only 64.3 +/- 1.9% of the Ins(1,4,5)P3-sensitive intracellular Ca2+ pools. 3F-Ins(1)P-(4,5)PS2 was unique among the Ins(1,4,5)P3 receptor partial agonists so far identified in having a relatively high affinity for the Ins(1,4,5)P3 binding site, accompanied by a significant loss of intrinsic activity for Ca2+ mobilisation. This improved affinity was probably due to the retention of the 1-position phosphate, which enhances interaction with the Ins-(1,4,5)P3 receptor. 3F-Ins(1)P-(4,5)PS2 may be an important lead compound for the development of efficient Ins(1,4,5)P3 receptor antagonists.

摘要

新型合成类似物D-3-氟-肌醇1,5-二磷酸-4-硫代磷酸酯[3F-Ins(1,5)P2-4PS]、D-3-氟-肌醇1,4-二磷酸-5-硫代磷酸酯[3F-Ins(1,4)P2-5PS]和D-3-氟-肌醇1-磷酸-4,5-二硫代磷酸酯[3F-Ins(1)P-(4,5)PS2]被用于确定结构-活性关系，这些关系可能在动员Ca2+的肌醇1,4,5-三磷酸[Ins(1,4,5)P3]受体上产生部分激动作用。基于先前的结构-活性数据，我们推测Ins(1,4,5)P3受体部分激动作用的最小结构要求是关键的邻位4,5-二磷酸对的硫代磷酸酯取代，并伴有另一种结构扰动，如肌醇环3位的氟化。所有类似物在猪小脑膜的单个Ins(1,4,5)P3结合位点上完全取代了[3H]Ins(1,4,5)P3[3F-Ins(1,5)P2-4PS(IC50 = 26 nM)、3F-Ins(1,4)P2-5PS(IC50 = 80 nM)和3F-Ins(1)P-(4,5)PS2(IC50 = 109 nM)，对比Ins(1,4,5)P3(IC50 = 11 nM)]。相比之下，3F-Ins(1,5)P2-4PS(IC50 = 424 nM)和3F-Ins(1,4)P2-5PS(IC50 = 3579 nM)在通透的SH-SY5Y神经母细胞瘤细胞的动员Ca2+的Ins(1,4,5)P3受体上是弱的完全激动剂，效力分别比Ins(1,4,5)P3(EC50 = 99 nM)低4倍和36倍。而3F-Ins(1)P-(4,5)PS2(EC50 = 11345 nM)是一种部分激动剂，仅释放64.3±1.9%的Ins(1,4,5)P3敏感的细胞内Ca2+池。3F-Ins(1)P-(4,5)PS2在迄今鉴定的Ins(1,4,5)P3受体部分激动剂中是独特的，它对Ins(1,4,5)P3结合位点具有相对较高的亲和力，同时Ca2+动员的内在活性显著丧失。这种亲和力的提高可能是由于1位磷酸的保留，这增强了与Ins-(1,4,5)P3受体的相互作用。3F-Ins(1)P-(4,5)PS2可能是开发高效Ins(1,4,5)P3受体拮抗剂的重要先导化合物。