Molecular analysis of the structural function of angiotensin II receptors for new therapeutic strategy

血管紧张素II （Ang II）受体的两种不同亚型，1型（AT1）和2型（AT2），它们是g蛋白偶联受体超家族（gpcr）的成员，已经被鉴定出来。多种信号通路将AT1受体连接到gq依赖性肌醇磷酸（IP）的产生和gq依赖性磷酸化细胞外信号激活激酶（p-ERK）1/2，分别通过Ang II调节心血管血管收缩和细胞生长。Ang II类似物[Sar^1， Ile^4， Ile^8]Ang II不刺激gq依赖性IP的产生，但仍然激活了人冠状动脉平滑肌细胞和稳定表达AT^1受体的细胞系中gq非依赖性p-ERK1/2。这种激活主要是由[Sar^1， Ile^4， Ile^8]Ang ii诱导的gq非依赖性表皮生长因子受体转激活介导的。我们发现AT^1受体信号显示分叉成功能独立的途径。此外，GPCRs的成员经过同源和/或异寡聚体化来诱导细胞信号传导。虽然其中一些显示组成激活，但尚不清楚这些gpcr是如何通过跨膜（TM）螺旋运动进行同质寡聚化的。我们之前报道过AT2受体表现出独立于其配体Ang II的组成性激活和诱导凋亡。因此，我们分析了AT2受体在诱导细胞信号传导时，随TM运动而发生的易位和寡聚化。一种AT2受体中的Cys35和另一种AT2受体中的Cys290之间的二硫键形成了组成性活性的同质寡聚化，在没有Ang II刺激的情况下定位于细胞膜，并在不改变受体构象的情况下诱导凋亡。这些结果提供了直接证据，证明组成型活性同源寡聚gpcr通过两个细胞外环的分子间相互作用易位到细胞膜并诱导细胞信号传导，而不依赖于受体构象和配体刺激。在分子生物学研究的基础上，我们发现了Ang II受体的结构和功能的新发现，以及针对这些受体的可能的新的治疗策略。少

Two distinct subtypes of angiotensin II (Ang II) receptors, type 1(AT1) and type 2 (AT2), which are members of the G-protein-coupled receptor superfamily (GPCRs), have been identified.Multiple signaling pathways link AT1 receptor to Gq-dependent inositol phosphate (IP) production and Gq-independent phospho-extracellular signal-activated kinase(p-ERK)1/2 by Ang II in the regulation of cardiovascular vasoconstriction and cell growth, respectively. An Ang II analogue, [Sar^1, Ile^4, Ile^8]Ang II, did not stimulate Gq-dependent IP production, but still activated Gq-independent p-ERK1/2 in human coronary artery smooth muscle cells as well as in a cell line that stably expressed AT^1 receptor. This activation was mostly mediated by [Sar^1, Ile^4, Ile^8]Ang II-induced Gq-independent epidermal growth factor receptor transactivation. We found that AT^1 receptor signaling shows bifurcation into functionally separate pathways.In addition, members of the GPCRs undergo homo- and/or hetero-oligomeri … More zation to induce cell signaling. Although some of these show constitutive activation, it is not clear how such GPCRs undergo homo-oligomerization with transmembrane (TM) helix movement. We previously reported that AT2 receptor showed constitutive activation and induced apoptosis independent of its ligand, Ang II. Therefore, we analyzed the translocation and oligomerization of AT2 receptor with TM movement when the receptor induces cell signaling. Constitutively active homo-oligomerization, which was due to disulfide bonding between Cys35 in one AT2 receptor and Cys290 in another AT2 receptor, was localized in the cell membrane without Ang II stimulation and induced apoptosis without changes in receptor conformation. These results provide the direct evidence that the constitutive active homo-oligomeric GPCRs by intermolecular interaction in two extracellular loops is translocated to the cell membrane and induces cell signaling independent of receptor conformation and ligand stimulation.Based on molecular biological studies, we found new findings on the structure and function of Ang II receptors and possible new therapeutic strategies for targeting these receptors. Less