Burghi Valeria, Echeverría Emiliana B, Sosa Máximo H, Quiroga Diego T, Muñoz Marina C, Davio Carlos, Monczor Federico, Fernández Natalia C, Dominici Fernando P
Facultad de Farmacia y Bioquímica, Instituto de Investigaciones Farmacológicas (ININFA), Universidad de Buenos Aires, Consejo Nacional de Investigaciones Científicas y Técnicas, Buenos Aires, Argentina.
Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Consejo Nacional de Investigaciones Científicas y Técnicas, Instituto de Química y Fisicoquímica Biológicas (IQUIFIB), Buenos Aires, Argentina.
Front Pharmacol. 2019 Feb 22;10:146. doi: 10.3389/fphar.2019.00146. eCollection 2019.
The MasR receptor (MasR) is an orphan G protein-coupled receptor proposed as a candidate for mediating the angiotensin (Ang)-converting enzyme 2-Ang-(1-7) protective axis of renin-angiotensin system. This receptor has been suggested to participate in several physiological processes including cardio- and reno-protection and regulation of the central nervous system function. Although the knowledge of the signaling mechanisms associated with MasR is essential for therapeutic purposes, these are still poorly understood. Accordingly, in the current study we aimed to characterize the signaling pathways triggered by the MasR. To do that, we measured cAMP and Ca levels in both naïve and MasR transfected cells in basal conditions and upon incubation with putative MasR ligands. Besides, we evaluated activation of ERK1/2 by Ang-(1-7) in MasR transfected cells. Results indicated the existence of a high degree of MasR constitutive activity toward cAMP modulation. This effect was not mediated by the PDZ-binding motif of the MasR but by receptor coupling to Gαi-adenylyl cyclase signaling pathway. Incubation of MasR transfected cells with Ang-(1-7) or the synthetic ligand AVE 0991 amplified MasR negative modulation of cAMP levels. On the other hand, we provided evidence for lack of MasR-associated modulation of Ca levels by Ang-(1-7). Finally, it was determined that the MasR attenuated Ang-(1-7)-induced ERK1/2 phosphorylation mediated by AT1R. We provided further characterization of MasR signaling mechanisms regarding its constitutive activity and response to putative ligands. This information could prove useful to better describe MasR physiological role and development of therapeutic agents that could modulate its action.
MasR受体（MasR）是一种孤儿G蛋白偶联受体，被认为是介导肾素-血管紧张素系统中血管紧张素（Ang）转换酶2-Ang-（1-7）保护轴的候选者。该受体已被提示参与多种生理过程，包括心脏和肾脏保护以及中枢神经系统功能的调节。尽管了解与MasR相关的信号传导机制对于治疗目的至关重要，但目前对这些机制仍知之甚少。因此，在本研究中，我们旨在表征由MasR触发的信号通路。为此，我们在基础条件下以及与假定的MasR配体孵育后，测量了未转染细胞和MasR转染细胞中的cAMP和Ca水平。此外，我们评估了Ang-（1-7）在MasR转染细胞中对ERK1/2的激活作用。结果表明，MasR对cAMP调节存在高度的组成性活性。这种作用不是由MasR的PDZ结合基序介导的，而是由受体与Gαi-腺苷酸环化酶信号通路偶联介导的。用Ang-（1-7）或合成配体AVE 0991孵育MasR转染细胞，可增强MasR对cAMP水平的负调节作用。另一方面，我们提供证据表明Ang-（1-7）对Ca水平缺乏与MasR相关的调节作用。最后，确定MasR减弱了由AT1R介导的Ang-（1-7）诱导的ERK1/2磷酸化。我们进一步表征了MasR信号传导机制的组成性活性及其对假定配体的反应。这些信息可能有助于更好地描述MasR的生理作用以及开发能够调节其作用的治疗药物。
