Evidence that the angiotensin IV (AT4) receptor is the enzyme insulin-regulated aminopeptidase
Evidence that the angiotensin IV (AT4) receptor is the enzyme insulin-regulated aminopeptidase
复制标题
DOI：
10.1074/jbc.c100512200
复制
发表时间：
2001-12-28
影响因子：
4.8
通讯作者：
Chai, SY
中科院分区：
文献类型：
--
作者：
Albiston, AL;McDowall, SG;Chai, SY
血管紧张素IV或其更稳定的类似物的中枢输注促进正常动物的记忆保持和提取，并逆转东莨菪碱或双侧穿通通路病变引起的遗忘。这些肽以高亲和性和特异性结合一个新的结合位点，称为血管紧张素AT（4）受体。到目前为止，AT（4）受体还没有分子特征。在这里，我们通过蛋白质纯化和肽测序鉴定AT（4）受体是胰岛素调节氨肽酶（IRAP）。用IRAP转染的HEK 293 T细胞表现出典型的AT（4）受体结合特征; AT（4）受体配体血管紧张素IV和LVV-血红素7竞争[I-125]Nle（1）-血管紧张素IV的结合，IC 50值分别为32和140 nM。免疫组织化学和杂交组织化学测定的IRAP及其mRNA在脑中的分布与放射性配体结合测定的AT（4）受体的分布平行。我们还发现AT（4）受体配体剂量依赖性地抑制IRAP的催化活性。因此，我们已经证明AT（4）受体是IRAP，并提出AT（4）受体配体可能通过抑制IRAP的催化活性从而延长其神经肽底物的半衰期来发挥其作用。
Central infusion of angiotensin IV or its more stable analogues facilitates memory retention and retrieval in normal animals and reverses amnesia induced by scopolamine or by bilateral perforant pathway lesions. These peptides bind with high affinity and specificity to a novel binding site designated the angiotensin AT(4) receptor. Until now, the AT(4) receptor has eluded molecular characterization. Here we identify the AT(4) receptor, by protein purification and peptide sequencing, to be insulin-regulated aminopeptidase (IRAP). HEK 293T cells transfected with IRAP exhibit typical AT(4) receptor binding characteristics; the AT(4) receptor ligands, angiotensin IV and LVV-hemorphin 7, compete for the binding of [I-125]Nle(1)-angiotensin IV with IC50 values of 32 and 140 nM, respectively. The distribution of IRAP and its mRNA in the brain, determined by immunohistochemistry and hybridization histochemistry, parallels that of the AT(4) receptor determined by radioligand binding. We also show that AT(4) receptor ligands dose-dependently inhibit the catalytic activity of IRAP. We have therefore demonstrated that the AT(4) receptor is IRAP and propose that AT(4) receptor ligands may exert their effects by inhibiting the catalytic activity of IRAP thereby extending the half-life of its neuropeptide substrates.