CAREER: Molecular mechanisms of pH sensitive proteins, pathways, and cell behaviors

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Maintaining intracellular pH (pHi) is vital in normal cellular physiology including metabolism, cellular growth, and cellular division, with even small changes in pHi having a drastic effect on cellular processes. While the role for pHi in regulating biology is clear, the proteins and biomolecules that sense these small changes in pHi are largely unknown. Furthermore, there are no good tools to manipulate and measure pHi in single cells thereby limiting progress in this field. In this project, the PI will determine the molecular mechanisms driving pH sensitive proteins, reveal how pH dynamics drive single-cell behaviors, and develop next-generation tools for changing pHi in living cells. This project will further our understanding of how pHi regulates single-cell biology and will reveal the molecular mechanisms of how proteins sense and respond to pHi. The new tools to manipulate cell pHi will also be applicable to other fields, including understanding how pHi drives pathological processes. For the Broader Impacts of this project, the PI will develop a transformative education program to explore scientific research as a creative endeavor. This includes developing project-based learning curriculum for undergraduate students and implementing activity-based learning modules for STEAM (Science, Technology, Engineering, Art, and Mathematics) education in middle school art classrooms. These modules will cultivate an innovation mindset, strengthen interdisciplinary skills, and build positive associations of science as a creative endeavor, which has been shown to encourage students to pursue STEM.Human cells normally maintain an intracellular pH (pHi) between 7.0 and 7.2 but increases in pHi to ~7.6 can signal cells to divide, to move, or to change their metabolism. While the role for pHi in regulating biology is clear, the proteins and biomolecules that sense these small changes in pHi are largely unknown. Thus, this project will address major gaps in the field of pH-sensitive biology. First, the PI will use recently validated optogenetic tools to probe how spatiotemporal pH dynamics regulate single-cell behaviors including cell migration and polarity changes. Second, the PI will leverage the sodium-proton exchanger (NHE1) as a foundation for protein engineering in order to develop a suite of next-generation optogenetic tools to raise pHi for hours to days. Third, the PI will determine the molecular mechanisms underlying pH-sensing by ionizable residue networks, specifically in various SH2-domain-containing signaling proteins that regulate pH-sensitive biology. This work will reveal how pHi dynamics drive single cell biology as well as support future work investigating pH-dependent cellular pathways and essential design principles of pH sensitive proteins.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.