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

血管紧张素 II (Ang II) 受体有两种不同的亚型，即 1 型 (AT1) 和 2 型 (AT2)，它们都是 G 蛋白偶联受体超家族 (GPCR) 的成员。在心血管调节中，多种信号通路将 AT1 受体与 Gq 依赖性磷酸肌醇 (IP) 的产生以及 Ang II 的不依赖于 Gq 的磷酸细胞外信号激活激酶 (p-ERK)1/2 连接起来。分别是血管收缩和细胞生长。 Ang II 类似物 [Sar^1, Ile^4, Ile^8]Ang II 不会刺激 Gq 依赖性 IP 产生，但仍然在人冠状动脉平滑肌细胞以及稳定表达 AT^1 受体的细胞系中激活 Gq 独立的 p-ERK1/2。这种激活主要是由 [Sar^1、Ile^4、Ile^8]Ang II 诱导的 Gq 独立表皮生长因子受体反式激活介导的。我们发现 AT^1 受体信号传导显示出分叉成功能上独立的途径。此外，GPCR 的成员经历同源和/或异源寡聚化以诱导细胞信号传导。尽管其中一些显示出组成型激活，但尚不清楚此类 GPCR 如何通过跨膜 (TM) 螺旋运动进行同源寡聚化。我们之前报道过 AT2 受体表现出组成型激活并诱导细胞凋亡，不依赖于其配体 Ang II。因此，我们分析了当AT2受体诱导细胞信号传导时，AT2受体随TM运动的易位和寡聚化。组成型活性同源寡聚化是由于一种 AT2 受体中的 Cys35 与另一种 AT2 受体中的 Cys290 之间的二硫键形成的，在没有 Ang II 刺激的情况下定位于细胞膜并诱导细胞凋亡而不改变受体构象。这些结果提供了直接证据，表明通过两个细胞外环中的分子间相互作用，组成型活性同源寡聚GPCR易位至细胞膜，并诱导独立于受体构象和配体刺激的细胞信号传导。基于分子生物学研究，我们发现了关于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治疗策略。较少的

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