RAS pathway mutations are linked to ~25% of all human cancers and cause birth defects that affect approximately 1/1000 human births. Moreover, RAS has proven frustratingly intractable to classical genetic and pharmaceutical approaches, establishing an urgent need for new approaches and therapies to understand and treat RAS-driven disease. Exciting recent work, much of it from my new host lab (the Levin lab), has shown that bioelectric signals can prevent and normalize RAS-driven tumors. Developmental bioelectricity has been implicated in a range of developmental processes, including left-right patterning, brain morphogenesis, and eye development. Moreover, bioelectric interventions stimulate regeneration in otherwise non-regenerative organs and to induce formation of ectopic eyes throughout the body of a developing embryo. Craniofacial development is one of the most striking examples of bioelectric signaling, which manifests as an endogenous 'Electric Face' of dynamic patterns of de- and hyperpolarization that precede and instruct morphogenesis. A major knowledge gap exists regarding how bioelectric signals interface with classical genetic pathways like RAS signaling. The goal of this proposal is to understand the functional relationship between these crucial signaling nodes during craniofacial development in the highly tractable Xenopus laevis model. The external development of Xenopus facilitates bioelectric studies since membrane potential can only be measured in living cells. We observed that ectopically activating the RAS pathway induces severe craniofacial abnormalities, and thus established Xenopus as a model for RASopathies like Noonan syndrome.
Aim 1 will be to characterize these craniofacial abnormalities using both molecular-genetic and bioelectric approaches and integrating these findings into a computational model comprising the KRAS pathway, bioelectric signaling, and transcriptional changes. Connecting bioelectric and RAS signaling will both provide novel mechanistic insights to the pathology of RASopathies and inform future experiments aimed at rescuing craniofacial abnormalities using bioelectric effectors.
Aim 2 will test the computational model in the context of functional experiments to repair RAS-induced craniofacial abnormalities. The optogenetic approaches that have previously been successfully used to promote regeneration of tails and prevent/normalize RAS-induced tumors will be exploited as new tools to repair RAS induced craniofacial defects. Finally, the bioelectric circuitry of the developing face will be re-wired by altering connectivity patterns of gap junctions (electrical synapses), as guided by the computational modeling, to restore proper craniofacial morphology to embryos with RAS-induced defects. Thus, the key RAS and bioelectric developmental signaling nodes will be integrated into a computational model, and the predictions made by this model will be used to devise and test bioelectric interventions that will underpin new regenerative therapies for RAS-dependent craniofacial diseases.

Public Health Relevance

Therapeutically intractable RASopathies cause a wide variety of birth defects, including craniofacial abnormalities. Bioelectric signals have been used to prevent and normalize RAS-driven tumors. We will integrate the key RAS and bioelectric developmental signaling nodes into a computational model and use this model to devise and test bioelectric interventions that will underpin new regenerative therapies for RAS- dependent craniofacial diseases.

National Institute of Health (NIH)
National Institute of Dental & Craniofacial Research (NIDCR)
Postdoctoral Individual National Research Service Award (F32)
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NIDR Special Grants Review Committee (DSR)
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Frieden, Leslie A
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Tufts University
Schools of Arts and Sciences
United States
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