Michael Hilzendeger

Program: Cancer Biology

Current advisor: Rotating in the lab of Charles Kaufman, MD, PhD

Undergraduate university: University of Virginia

Research summary
In this rotation, I studied the phenomenon of lysosomal membrane permeabilization (LMP), a process by which loss of integrity of the lysosomal membrane releases the contents (mainly proteases) of this organelle in to the cell, which can induce cell damage and trigger cell death. Ionizing radiation is known to induce LMP, and release lysosomal contents into the cytosol. My main focus in the rotation was to develop a reliable readout for LMP that is amenable to analysis via flow cytometry. My workflow included optimizing LysoTracker staining, which is a fluorophore that fluoresces in the presence of the acidic compartment of the lysosome. Interestingly, my research showed that IR actually increased LysoTracker staining, suggesting that IR-induced damage expands the lysosomal compartment after injury or consolidates the existing compartment. I also investigated the protease activity of lysosomes isolated from cervical cancer cell lines before and after LMP was induced and found that a pull-down based method of isolation preserved the protease activity of lysosomes while a column-based lysosome isolation kit did not preserve lysosomal protease activity.

Graduate publications