Julia Spear, a fifth year graduate student in the laboratory of Katharine White, Clare Booth Luce Assistant Professor, has been profiled by the Journal of Cell Science for her recent publication. The paper, entitled “Single-cell intracellular pH dynamics regulate the cell cycle by timing G1 exit and the G2 transition,” appears in Volume 136, Issue 10 of the journal.
Her research focuses on the study of how intracellular pH (pHi) changes during cell cycle progression. Normal human epithelial cells function in a pHi range of 7.0-7.2, but transient pHi changes are necessary for cell behaviors such as cell movement, cell division, and programmed cell death. While it is known that pHi changes during these processes, very little is known of the detailed nature of how pHi varies with time or across heterogeneous cell populations. Spear was able to investigate these details using microscopy to measure pHi in single cells using a fluorescent biosensor. She captured images as cells progressed through the cell cycle and found that single cell pHi oscillates during growth and division, with dynamic pHi values corresponding to specific events in the cycle. Additionally, she found that manipulating pHi can alter the lengths and transitions of cell cycle stages. Ultimately, being able to accurately describe pHi over time improves the understanding of how cells time and regulate cell division. This work also suggests routes for therapeutically manipulating or perturbing the cell cycle in normal pH-dependent cell processes like wound healing or in diseases with dysregulated pHi such as cancer and neurodegeneration.
Spear first began research during the summer before her senior year at Susquehanna University prior to coming to Notre Dame. She credits White’s guidance and mentorship in helping to achieve these important research results. After graduation, Spear plans to pursue either a postdoctoral fellowship or an industrial job with a biology focus.