Importance of co-expression and co-activation of AT1, thromboxane A2 and EGF(HER1) receptors for angiotensin II-mediated signaling in vascular cells: analysis of molecular and functional interactions - part 2

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Angiotensin II (Ang II) induces endothelial dysfunction, vascular remodeling, and atherosclerosis as well as abdominal aortic aneurysm formation through activation of the AT1 receptor (AT1R). With regard to the pathological effects of Ang II in vascular cells, it is becoming increasingly clear that only the parallel activation of additional receptor types triggers full-scale Ang II-mediated signal transduction.In the first phase of the project, we demonstrated, for example, that EGF receptors (EGFR) or thromboxane A2 receptors (TP) expressed in vascular smooth muscle cells promote high-fat diet-induced vascular changes and atherosclerosis. In addition, our preliminary work reveals molecular and functional interactions of AT1R, TP, and EGFR with potential relevance to signal transduction, gene expression, and vascular cell homeostasis. Therefore, the proposed second phase of the project will further investigate how the interactions of the receptors AT1R, TP, and EGFR affect Ang II-induced cellular signal transduction, subsequent control of gene expression, and cell physiological consequences in vascular cells. To test this hypothesis, work packages (WP) will be addressed at the levels of (i) biophysical receptor interaction, (ii) cellular interaction of downstream signaling pathways, and (iii) cell physiological consequences of receptor interaction in vitro and in vivo. Continuing our cell biological approach and using validated FRET microscopy methods, mechanisms of receptor-receptor interaction will be investigated as well as whether AT1R-EGFR-TP triple complexes form in living cells. In addition, the Ang II-induced signalosome of vascular cells will be analyzed with particular emphasis on receptor-receptor interactions using mass spectrometric methods followed by validating Western Blot analyses (WP1). In addition, the characterization of receptor interaction with respect to intracellular signaling pathways of SRF transcriptional control will be continued (WP2), an analysis of receptor interaction for transcriptome regulation in human vascular cells will be pursued (WP3), and an experimental validation of bioinformatic predictions of (patho)physiological changes in human vascular cells will be performed (WP4 and WP5). Ultimately, the therapeutic potential of pharmacological blockade of EGFR and TP for Ang II-induced aortic atherogenesis and aneurysm formation, cardiac hypertrophy and mortality in ApoE knockout mice will be tested in vivo (AP6). We anticipate that the project will help clarify the importance of functional and molecular interactions between AT1R, TP, and EGFR for Ang II-mediated effects on vascular cells. By improving mechanistic understanding, it is expected to support the development of rational pharmacological therapeutic strategies for vascular diseases.