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：1型(AT1)和2型(AT2)，它们是G蛋白偶联受体超家族(GPCRs)的成员。多条信号通路分别将AT1受体与依赖Gq的磷酸肌醇(IP)的产生和Ang II调节心血管收缩和细胞生长的非Gq依赖的磷酸化细胞外信号激活激酶(p-ERK)1/2联系起来。Ang II类似物[Sar^1，Ile^4，Ile^8]Ang II不能刺激Gq依赖性IP的产生，但仍能激活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非依赖性的p-ERK1/2。这种激活主要由[Sar^1，Ile^4，Ile^8]Ang II诱导的Gq非依赖性表皮生长因子受体反式激活所介导。我们发现，AT^1受体信号通路在功能上分成不同的通路。此外，GPCR成员经历同源和/或异源寡聚体…更多的诱导细胞信号传递的过程。尽管其中一些表现出结构性激活，但尚不清楚这些GPCRs如何通过跨膜(TM)螺旋运动进行同源齐聚。我们曾报道AT2受体呈结构性激活并诱导细胞凋亡，而不依赖其配体Ang II。因此，我们分析了AT2受体在诱导细胞信号转导时的移位和寡聚化。由于AT2受体上的Cys35和AT2受体上的Cys290之间的二硫键作用而导致的结构性活性同源齐聚，在没有Ang II刺激的情况下定位在细胞膜上，并在没有受体构象变化的情况下诱导了细胞凋亡。这些结果为血管紧张素Ⅱ受体的结构和功能提供了直接的证据，证明了通过胞外两个环的分子间相互作用，GPCRs被转移到细胞膜上，并诱导不依赖于受体构象和配体刺激的细胞信号。在分子生物学研究的基础上，我们对Ang II受体的结构和功能有了新的发现，并可能针对这些受体制定新的治疗策略。较少

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