Abstract 2619: Characterization of RAS assembly architectures in living cells

Abstract Assembly of RAS proteins and RAS effectors into “nanoclusters” at the cell membrane regulates RAS signaling output. The structure and composition of membrane-bound RAS complexes is dynamic, but defined states appear to exist. We previously found biological and biophysical evidence for two different models of membrane-bound RAS assemblies where RAS proteins form symmetric or asymmetric RAS-RAS interactions. It is unknown what functions these two architectures might serve and what determinants these nanoclusters might be subject to. To further characterize which architectural states occur in various biological scenarios, we developed a plate-based assay to detect RAS-RAS interactions in cells. The system controls for RAS expression and can be used to discriminate symmetric and asymmetric RAS-RAS interactions. It can also be used to assess the relative contributions of the G domain (1-166) and hypervariable region (HVR) in mediating RAS-RAS interactions. We found that RAS isoforms can homo- and hetero-dimerize and observed that the G domain contributes to RAS-RAS interactions, but that the HVR does not. We also found that the primary determinant of HVR interaction with the membrane is electrostatic charge. Regarding cancer-causing mutations, we found that in the KRAS G12D context, RAS-RAS interactions appear to favor asymmetric RAS-RAS interactions while KRAS Q61H favors symmetric RAS-RAS interactions. Citation Format: Zhiwei Zhou, Xing-Xiao Li, Cynthia Meyer, Yu-An Zhang, Deekshi Angira, Kenneth Westover. Characterization of RAS assembly architectures in living cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 2619.