Using APC to study GPCR-gated ion channels and discover biased GPCR modulators

In their recent book chapter in “Potassium Channels: Methods and Protocols,” Ciria C. Hernandez, Luis E. Gimenez, and Roger D. Cone describe a very interesting application of Automated Patch Clamp (APC) technology to advance the study of GPCR-gated ion channels and accelerate the discovery of biased modulators of GPCRs.

GPCRs are critical drug targets due to their essential role in cellular signaling. Upon ligand binding, GPCRs can activate or block multiple distinct intracellular signaling pathways through various mechanisms, including heterotrimeric G proteins and β-arrestins. Some ligands, however, can stabilize specific GPCR conformations, selectively activating or blocking specific signaling pathways over others. This phenomenon, known as biased signaling, has important implications for drug development, as it allows the design of ligands that selectively activate specific therapeutic pathways while avoiding the unwanted side effects mediated by other signaling modalities.

A number of GPCRs are known to indirectly or directly regulate ion channel gating, suggesting that ion channel assays, such as patch clamp, might provide insights into GPCR function and modulation. This is exactly what Ciria Hernandez et al. presented in their book chapter. The authors focused on the melanocortin 4 receptor (MC4-R), which couples with the Kir7.1 potassium channel to regulate neuronal excitability within the hypothalamus, impacting energy homeostasis, appetite, and body weight.

Employing the SyncroPatch 384 APC system, the authors developed an assay to evaluate the coupling of the MC4-R/Kir7.1 complex based on real-time detection of the Kir7.1 channel response. They then validated this assay for primary drug screening and demonstrated reliable and reproducible currents from MC4-R- and Kir7.1-expressing cells, confirming the system’s effectiveness in screening potential therapeutic MC4-R modulators. Their pilot screen of 1,280 small molecule compounds identified 68 potentiators and 30 antagonists of the MC4-R/Kir7.1 complex.

Overall, the successful use of APC technology in studying the MC4-R/Kir7.1 complex illustrates its significant potential in studying GPCR-ion channel interactions. This approach will enhance our understanding of GPCR-gated ion channels and expedite the discovery of new biased modulators of GPCRs with improved efficacy and safety profiles.

Find the full book chapter here: Automated Patch Clamp Recordings of GPCR-Gated Ion Channels: Targeting the MC4-R/Kir7.1 Potassium Channel Complex

Learn more about automated patch clamp solutions from Nanion Technologies: https://www.nanion.de/product-categories/automated-patch-clamp/