Department of Pharmacology University of California Davis Davis CA USA.
Department of Cell Biology & Human Anatomy University of California Davis Davis CA USA.
J Am Heart Assoc. 2024 Oct 15;13(20):e035375. doi: 10.1161/JAHA.124.035375. Epub 2024 Oct 8.
Increased vascular Ca1.2 channel function causes enhanced arterial tone during hypertension. This is mediated by elevations in angiotensin II/protein kinase C signaling. Yet, the mechanisms underlying these changes are unclear. We hypothesize that α1 phosphorylation at serine 1928 (S1928) is a key event mediating increased Ca1.2 channel function and vascular reactivity during angiotensin II signaling and hypertension.
The hypothesis was examined in freshly isolated mesenteric arteries and arterial myocytes from control and angiotensin II-infused mice. Specific techniques include superresolution imaging, proximity ligation assay, patch-clamp electrophysiology, Ca imaging, pressure myography, laser speckle imaging, and blood pressure telemetry. Hierarchical "nested" and appropriate parametric or nonparametric test and ANOVAs were used to assess statistical differences. We found that angiotensin II redistributed the Ca1.2 pore-forming α1 subunit into larger clusters. This was correlated with elevated Ca1.2 channel activity and cooperativity, global intracellular Ca and contraction of arterial myocytes, enhanced myogenic tone, and altered blood flow in wild-type mice. These angiotensin II-induced changes were prevented/ameliorated in cells/arteries from S1928 mutated to alanine knockin mice, which contain a negative modulation of the α1 S1928 phosphorylation site. In angiotensin II-induced hypertension, increased α1 clustering, Ca1.2 activity and cooperativity, myogenic tone, and blood pressure in wild-type cells/tissue/mice were averted/reduced in S1928 mutated to alanine samples.
Results suggest an essential role for α1 S1928 phosphorylation in regulating channel distribution, activity and gating modality, and vascular function during angiotensin II signaling and hypertension. Phosphorylation of this single vascular α1 amino acid could be a risk factor for hypertension that may be targeted for therapeutic intervention.
血管中 Ca1.2 通道功能的增强会导致高血压期间动脉张力增加。这是通过血管紧张素 II/蛋白激酶 C 信号的升高来介导的。然而，这些变化的机制尚不清楚。我们假设α1 丝氨酸 1928 位（S1928）的磷酸化是介导血管紧张素 II 信号和高血压期间 Ca1.2 通道功能和血管反应性增强的关键事件。
该假说在来自对照和血管紧张素 II 输注小鼠的新鲜分离的肠系膜动脉和动脉肌细胞中进行了检验。具体技术包括超分辨率成像、邻近连接分析、膜片钳电生理学、钙成像、压力肌动描记术、激光散斑成像和血压遥测。采用分层“嵌套”和适当的参数或非参数检验和方差分析来评估统计学差异。我们发现血管紧张素 II 将 Ca1.2 孔形成的α1 亚基重新分布到更大的簇中。这与 Ca1.2 通道活性和协同性升高、细胞内 Ca 整体增加和动脉肌细胞收缩、增强的肌原性张力以及野生型小鼠血流改变相关。这些血管紧张素 II 诱导的变化在 S1928 突变为丙氨酸的敲入小鼠的细胞/动脉中被预防/减轻，这些小鼠含有对α1 S1928 磷酸化位点的负调节作用。在血管紧张素 II 诱导的高血压中，野生型细胞/组织/小鼠中α1 聚集、Ca1.2 活性和协同性、肌原性张力和血压的增加在 S1928 突变为丙氨酸的样本中被避免/减少。
结果表明，α1 S1928 磷酸化在调节血管紧张素 II 信号和高血压期间通道分布、活性和门控模式以及血管功能方面起着重要作用。这种血管α1 单个氨基酸的磷酸化可能是高血压的一个危险因素，可能成为治疗干预的靶点。
