Characterization of LSD1 Expression Within the Murine Eye

• Type of Material: Article
• Authors: Salma Ferdous, Emory University; Hans Grossniklaus, Emory University; Jeffrey Boatright, Emory University; John Nickerson, Emory University
• Language: English
• Date: 2019-11-01
• Publisher: Association for Research in Vision and Ophthalmology (ARVO)
• Publication Version: Final Published Version
• Copyright Statement: Copyright 2019 The Authors
• License: Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International
• Final Published Version (URL): http://dx.doi.org/10.1167/iovs.19-26728
• Title of Journal or Parent Work: Investigative Ophthalmology & Visual Science
• ISSN: 0146-0404
• Volume: 60
• Issue: 14
• Start Page: 4619
• End Page: 4631
• Grant/Funding Information: Supported by the National Institutes of Health Grants R01EY028450, R01EY021592, P30EY006360, F31EY028855, R01EY028859, T32EY07092, and T32GM008490; the Abraham and Phyllis Katz Foundation; Veterans Affairs Rehabilitation Research & Development I01RX002806 and I21RX001924; Veterans Affairs Rehabilitation Research & Development C9246C (Atlanta Veterans Administration Center for Excellence in Vision and Neurocognitive Rehabilitation); and an unrestricted grant to the Department of Ophthalmology at Emory University from Research to Prevent Blindness, Inc.
• Keywords: PROTEINS; epigenetics; ocular development; MARKER; EPIGENETICS; Science & Technology; LSD1; LIGHT; heterochromatin; FEATURES; Ophthalmology; retinal development; rod and cone photoreceptors; DEMETHYLATION; histone demethylation; Life Sciences & Biomedicine; DIFFERENTIATION; RETINAL GANGLION-CELLS; euchromatin; HETEROCHROMATIN
• Research Categories: Health Sciences, Opthamology

Abstract

PURPOSE. The purpose of this study was to extend the current understanding of endogenous lysine-specific demethylase 1 (LSD1) expression spatially and temporally in the retina. Toward that end, we determined the localization and levels of LSD1 and its substrates H3K4me1 and H3K4me2 (H3K4me1/2) within the murine eye. METHODS. Immunofluorescent microscopy for LSD1, H3K4me1, and H3K4me2 was conducted on murine formalin-fixed paraffin-embedded eye sections across development in addition to Western immunoblotting to assess localization and protein levels. RESULTS. Retinal LSD1 protein levels were highest at postnatal day 7 (P7), whereas its substrates H3K4me1 and H3K4me2 had equally high levels at P2 and P14. Concentrations of all three proteins gradually decreased over developmental time until reaching a basement level of ~60% of maximum at P36. LSD1 and H3K4me1/2 were expressed uniformly in all retinal progenitor cells. By P36, there was variability in LSD1 expression in the ganglion cell layer, uniform expression in the inner nuclear layer, and dichotomous expression between photoreceptors in the outer nuclear layer. This contrasted with H3K4me1/2 expression, which remained uniform. Additionally, LSD1 was widely expressed in the lens, cornea, and retinal pigment epithelium. CONCLUSIONS. Consistent with its known role in neuronal differentiation, LSD1 is highly and uniformly expressed throughout all retinal progenitor cells. Variability in LSD1 expression, particularly in photoreceptors, may be indicative of their unique transcriptomes and epigenetic patterns of rods and cones. Murine rod nuclei exhibit LSD1 expression in a ring or shell, rather than throughout the nucleus, consistent with their unique inverted chromatin organization. LSD1 has substantial expression throughout adulthood, especially in cone nuclei. By providing insight into endogenous LSD1 expression, our current findings could directly inform future studies to determine the exact role of Lsd1 in the development and maintenance of specific structures and cell types within the eye.