Biological Chemistry Department, University of Michigan Medical School, Ann Arbor, MI, 48109, USA.
Biological Chemistry Department, University of Michigan Medical School, Ann Arbor, MI, 48109, USA; Undergraduate Honors Program, University of Michigan, Ann Arbor, MI, 48109, USA.
Peptides. 2021 Dec;146:170641. doi: 10.1016/j.peptides.2021.170641. Epub 2021 Aug 25.
The structural conservation and activity of the myosuppressin cardioinhibitory peptide across species suggests it plays an important role in physiology, yet much remains unknown regarding its signaling. We previously reported Drosophila melanogaster myosuppressin (dromyosuppressin, DMS; TDVDHVFLRF-NH) decreases cardiac contractility through a G protein-coupled receptor, DMS-R2. Our study showed the DMS N-terminus amino acids influence its structure-activity relationship (SAR), yet how they act is not established. We predicted myosuppressin N-terminal amino acids played a role in signaling. Here, we tested our hypothesis in the beetle, Zophobas atratus, using a semi-isolated heart bioassay to explore SAR in a different Order and focus on cardiac signaling. We generated a series of myosuppressin truncated analogs by removing the N-terminal residue and measuring the activity of each structure on cardiac contractility. While DVDHVFLRF-NH decreased cardiac contractility, we found VDHVFLRF-NH, DHVFLRF-NH, and HVFLRF-NH increased activity. In contrast, VFLRF- NH decreased activity and FLRF-NH was inactive. Next, we analyzed molecular docking data and found the active truncated analogs interacted with the 3-6 lock in DMS-R2, the myosuppressin cardiac receptor, disrupting the salt bridge between H114 and E369, and K289 and Q372. Further, the docking results showed the inhibitory effect on contractility may be associated with contact to Y78, while the analogs that increased contractility lacked this interaction. The data from our study demonstrated N-terminal amino acids played a role in myosuppressin activity and signaling suggesting the cardiac receptor can be targeted by biased agonists. Our myosuppressin cardiac contractility data and predicted receptor interactions describe the presence of functional selectivity in a ligand-directed signaling pathway in heart.
跨物种的肌抑制素心脏抑制肽的结构保守性和活性表明它在生理学中发挥着重要作用，但关于其信号转导仍有许多未知。我们之前报道了果蝇肌抑制素（dromyosuppressin，DMS；TDVDHVFLRF-NH）通过 G 蛋白偶联受体 DMS-R2 降低心脏收缩力。我们的研究表明，DMS 的 N 端氨基酸影响其结构-活性关系（SAR），但它们的作用方式尚未确定。我们预测肌抑制素 N 端氨基酸在信号转导中发挥作用。在这里，我们使用半分离心脏生物测定法在甲虫 Zophobas atratus 中测试了我们的假设，以探索不同目序中的 SAR，并关注心脏信号转导。我们通过去除 N 端残基生成了一系列肌抑制素截断类似物，并测量了每种结构对心脏收缩力的活性。虽然 DVDHVFLRF-NH 降低了心脏收缩力，但我们发现 VDHVFLRF-NH、DHVFLRF-NH 和 HVFLRF-NH 增加了活性。相比之下，VFLRF-NH 降低了活性，FLRF-NH 则没有活性。接下来，我们分析了分子对接数据，发现活性截断类似物与 DMS-R2（肌抑制素心脏受体）中的 3-6 锁结合，破坏了 H114 和 E369 之间的盐桥以及 K289 和 Q372。此外，对接结果表明，对收缩力的抑制作用可能与 Y78 的接触有关，而增加收缩力的类似物则缺乏这种相互作用。我们的研究数据表明，N 端氨基酸在肌抑制素的活性和信号转导中发挥作用，这表明心脏受体可以被偏倚激动剂靶向。我们的肌抑制素心脏收缩力数据和预测的受体相互作用描述了配体定向信号通路中功能选择性的存在。
