Rachel Lim
Pronouns: she/her
Research Mentor(s): Lev Prasov
Research Mentor School/College/Department: Ophthalmology and Visual Sciences; Human Genetics / Medicine
Program:
Authors: Rachel Lim, Gabrielle Rozumek, Michelle Brinkmeier, Su Wang, Lijin Dong, Robert Hufnagel, Lev Prasov
Session: Session 5: 2:40 pm – 3:30 pm
Poster: 65
Abstract
Our lab recently discovered a large family with a dominantly inherited frameshift C-terminal splice site mutation in the Myelin Regulatory Factor (MYRF) gene, which is highly and selectively expressed in the retinal pigment epithelium (RPE). The RPE is the barrier between the retina and the choroid and is important for the health and function of the retina. Mice generated with the humanized MYRF mutation (MYRFhumMUT) and humanized MYRF wildtype (MYRFhumWT) underwent single-cell RNA sequencing to define cell cycle changes and understand cell population differences. Preliminary results suggested that there were over 20% more RPE cells in the G2/M phase of the cell cycle in MYRFhumMUT eyes compared to the control. We hypothesize that RPE are delayed in cell cycle exit due to the MYRFhumMUT. To test our hypothesis, timed pregnant mice were injected with 5-ethynyl-2’-deoxyuridine (EdU) to label actively proliferating cells at embryonic day (E)13.5. We analyzed eye sections from MYRFhumWT/humMUT (HET, n=3) and MYRFhumMUT/humMUT (MUT, n=2) mice, quantifying EdU+/Otx2+ (RPE marker) RPE. We found similar levels of EdU+/Otx2+ cells between the genotypes. Staining for phospho-histone H3 (pHH3), a mitosis marker, showed a significant increase in central RPE in the MUT (0.8 ± 0.3%) over HET (0.1 ± 0.2%) mice, p=0.0464. Our findings at E13.5 suggest MUT mice have no difference in S-phase but show a greater number of central RPE undergoing mitosis as compared to the HET mice. Further studies will include new timed breedings for E17.5 mice to validate our cell cycle findings and define impacts on eye growth.
