Chemical Genetic Analysis of RAS Signaling

Abstract The GTPase RAS functions as a molecular “on/off” switch, existing both in GDP-bound (inactive) and GTP- bound forms (active). Despite functioning as a simple binary switch, RAS is capable of directing complex and diverse cellular processes, including proliferation, migration, survival, and T-cell development. Recent work suggests that the ability of RAS to play complex, often conflicting roles in diverse processes results from differences in cellular context and and/or subcellular localization of its signaling. We have developed a novel chemical genetic tool–called Chemically-Inducible Activator of RAS (CIAR)–to study the dynamics of the signaling networks that are mediated by RAS activity. CIAR allows rapid and dose-dependent activation of RAS signaling with a cell permeable small molecule. With CIAR, we propose to use targeted, quantitative phosphoproteomics and transcriptomics to study the fundamental dynamic behavior of RAS-driven signaling. Subcellularly-localized versions of CIAR will also be used to determine the effects of localized RAS activation on the dynamics of RAS-mediated signaling. Finally, we will explore positive and negative feedback within RAS-driven signaling pathways by selectively enhancing or inhibiting downstream signaling components.