"Examining RAS pathway rewiring with a chemically inducible activator of RAS"

A chemically-controlled system for activating RAS GTPases

RAS GTPases are involved in a number of dynamic signaling processes and have been a major focus of research due to the prevalence of activating RAS mutations in cancer. However, despite decades of research, some fundamental aspects of RAS biology are still not well understood. Difficulty in fully defining RAS-driven signaling stems from the overall complexity of downstream pathways and a lack of tools for specifically perturbing RAS function. To better characterize RAS-driven signaling, we recently developed a chemical genetic system for activating endogenous RAS with a small molecule. In this chapter, we describe the use of chemically inducible activator of RAS (CIAR), a single-protein, chemical genetic system that allows the rapid and dose-dependent activation of endogenous RAS. Methods in this chapter also describe the validation of RAS activation with CIAR through the analysis of downstream signaling.

SCN5A Nonsense Mutation and NF1 Frameshift Mutation in a Family With Brugada Syndrome and Neurofibromatosis

In this case series, we report for the first time a family in which the inherited nonsense mutation [c. 3946C > T (p.Arg1316*)] in the SCN5A gene segregates in association with Brugada syndrome (BrS). Moreover, we also report, for the first time, the frameshift mutation [c.7686delG (p.Ile2563fsX40)] in the NF1 gene, as well as its association with type 1 neurofibromatosis (NF1), characterized by pigmentary lesions (café au lait spots, Lisch nodules, freckling) and cutaneous neurofibromas. Both of these mutations and associated phenotypes were discovered in the same family. This genetic association may identify a subset of patients at higher risk of sudden cardiac death who require the appropriate electrophysiological evaluation. This case series highlights the importance of genetic testing not only to molecularly confirm the pathology but also to identify asymptomatic family members who need clinical examinations and preventive interventions, as well as to advise about the possibility of avoiding recurrence risk with medically assisted reproduction.

A Chemically Disrupted Proximity System for Controlling Dynamic Cellular Processes

Chemical methods that allow the spatial proximity of proteins to be temporally modulated are powerful tools for studying biology and engineering synthetic cellular behaviors. Here, we describe a new chemically controlled method for rapidly disrupting the interaction between two basally colocalized protein binding partners. Our chemically disrupted proximity (CDP) system is based on the interaction between the hepatitis C virus protease (HCVp) NS3a and a genetically encoded peptide inhibitor. Using clinically approved antiviral inhibitors as chemical disrupters of the NS3a/peptide interaction, we demonstrate that our CDP system can be used to confer temporal control over diverse intracellular processes. This NS3a-based CDP system represents a new modality for engineering chemical control over intracellular protein function that is complementary to currently available techniques.