Understanding How Rod Photoreceptors Regulate Time During Retinal Development
Discipline: Biological Sciences
Subcategory: biochemistry
Session: 2
Room: 1 - Hanover DE
Jackson Nguyen - Worcester Polytechnic Institute
Co-Author(s): Aikaterini Kalargyrou, Harvard University, Cambridge, MA Ryoji Amamoto, Harvard University, Cambridge, MA (Principal Investigator)
One of the most tantalizing questions in developmental biology has traditionally been how cells give rise to complex structures – a process regulated by numerous factors, including time. If time is not properly regulated, cells cannot respond to temporally specific signaling cues and fail to develop normally. To study time regulation, we utilized rod photoreceptors in the mouse retina, which exhibit a unique timekeeping mechanism. Prior research showed that late-born rod precursor cells do not begin to express Rhodopsin, a terminal differentiation marker, immediately after cell birth, but rather, they wait approximately six days after birth. We hypothesized a “timekeeper” protein that controls this intrinsic delay in Rhodopsin expression in late-born rod precursors post-birth. To test this hypothesis, we blocked protein degradation pathways via a proteasome inhibitor, MG-132, for 19 hours ex vivo and investigated the effects of Rhodopsin expression at various stages during rod development. To pinpoint when these rods were born, we accurately labeled these cells with their birthdates using EdU and VdU thymidine analogs. Then, to visualize the Rhodopsin marker, we used immunohistochemistry. Our results revealed that late-born rod cells treated with MG-132 not only reduced Rhodopsin expression but also delayed this reduction by approximately one postnatal development day. This finding highlights the potential role of protein degradation in regulating the timing of cellular differentiation, offering new insights into the molecular temporal mechanisms of cellular development.
Funder Acknowledgement(s): This work was supported by the 2024 Harvard-Amgen Scholars Program.
Faculty Advisor: Ryoji Amamoto, ramamoto@meei.harvard.edu
Role: During the summer of 2024, I participated in the Harvard-Amgen Scholars Program. I worked full-time (40 hours/week) in Dr. Ryoji Amamoto's retinal degeneration and development lab at Harvard University for 10 weeks. I was guided by both Dr. Aikaterini Kalargyrou, a postdoctoral mentor in the lab, as well as my PI. I performed key tasks such as retinal dissection, cell culturing, birthdating cells using click chemistry, conducting immunohistochemistry to stain for Rhodopsin, imaging cells with fluorescence microscopy, analyzing data using ImageJ, and creating graphs for presentations.