Abstract 3491: Designed sensors reveal normal and oncogenic Ras signaling in endomembranes and condensates

While Ras is known to dynamically shuttle around the cell, the activity, mechanism of activation, and function of non-plasma membrane-localized Ras is unclear due to lack of suitable tools. To address these questions, we used the Latching Orthogonal Cage-Key pRotein (LOCKR) switch platform to generate first-in-class intracellular sensors for endogenous Ras activity (Ras-LOCKR-S) and signaling-dependent proximity labelers (Ras-LOCKR-PL). We find that: 1) Receptor activation leads to endogenous Ras signaling at endomembranes, which is enhanced by golgi-localized guanine exchange factors. 2) Recruitment of SAM68 and MARCKS to oncogenic condensates fuels local Ras signaling and cell growth. 3) Major Vault Protein drives RasG12C inhibitor resistance by enhancing signaling at the golgi and altering mitochondrial metabolism. Together, these results highlight the importance of non-plasma membrane Ras signaling (endomembranes and condensates), and our new sensors should accelerate the discovery of new therapeutic targets. Citation Format: Jason Z. Zhang, William H. Nguyen, John C. Rose, Shao-En Ong, Dustin J. Maly, David Baker. Designed sensors reveal normal and oncogenic Ras signaling in endomembranes and condensates [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 3491.