G protein-coupled receptors (GPCRs) are a family of membrane proteins characterized by seven α-helical transmembrane domains and the ability to bind to extracellular signal to produce intracellular responses. Upon ligand binding, GPCRs undergo conformational changes that result in the dissociation of the attached heterotrimeric G protein complex to initiate a downstream signaling cascade via secondary messengers. Their membrane location and ability to generate a response inside the cells makes GPCRs ideal drug target, accounting for 35% of drugs on the market. Within the last decade, GPCRs have been shown to produce signaling responses through their interaction with β-arrestins, distinct from the canonical pathway via G-protein interaction. Here, we utilize yeast, a relatively simple and easy-to-use microbial system as a model to study not only canonical signaling but also β-arrestin-mediated non-canonical signaling. Yeast share many functionally exchangeable proteins with higher eukaryotes involved in the GPCR signaling pathway and thus can be easily modified to study both signaling pathways for human GPCRs. Angiotensin type II receptor type I (AGTR1) is a GPCR that binds to angiotensin II peptide and mediates its essential function in cardiovascular tissue. Biased ligands for AGTR1 that preferentially signal via β-arrestin have been shown to be clinically relevant to treat hypertension and improve cardiovascular health. With the aid of AGTR1, a well-established GPCR to study biased signaling response, we establish and validate engineered yeast to study “complete” GPCR signaling with the ability to screen biased ligands.  Results for AGTR1 expression, trafficking to the plasma membrane, ligand binding and downstream signaling in yeast will be discussed.

Yeast as a model to study biased signaling of GPCRs

2019 Spring National Meeting

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