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Updated: Dec 5, 2025
A Protocol to Evaluate and Quantify Retinal Pigmented Epithelium Pathologies in Mouse Models of Age-Related Macular Degeneration
Published on: March 10, 2023
Modulation of Tmem135 Leads to Retinal Pigmented Epithelium Pathologies in Mice
Michael Landowski1,2,3, Samuel Grindel1, Pawan K Shahi2,3
1Department of Medical Genetics, University of Wisconsin-Madison, Madison, Wisconsin, United States.
Purpose:
Aging is a critical risk factor for the development of retinal diseases, but how aging perturbs ocular homeostasis and contributes to disease is unknown. We identified transmembrane protein 135 (Tmem135) as a gene important for regulating retinal aging and mitochondrial dynamics in mice. Overexpression of Tmem135 causes mitochondrial fragmentation and pathologies in the hearts of mice. In this study, we examine the eyes of mice overexpressing wild-type Tmem135 (Tmem135 TG) and compare their phenotype to Tmem135 mutant mice.
Methods:
Eyes were collected for histology, immunohistochemistry, electron microscopy, quantitative PCR, and Western blot analysis. Before tissue collection, electroretinography (ERG) was performed to assess visual function. Mouse retinal pigmented epithelium (RPE) cultures were established to visualize mitochondria.
Results:
Pathologies were observed only in the RPE of Tmem135 TG mice, including degeneration, migratory cells, vacuolization, dysmorphogenesis, cell enlargement, and basal laminar deposit formation despite similar augmented levels of Tmem135 in the eyecup (RPE/choroid/sclera) and neural retina. We observed reduced mitochondria number and size in the Tmem135 TG RPE. ERG amplitudes were decreased in 365-day-old mice overexpressing Tmem135 that correlated with reduced expression of RPE cell markers. In Tmem135 mutant mice, RPE cells are thicker, smaller, and denser than their littermate controls without any signs of degeneration.
Conclusions:
Overexpression and mutation of Tmem135 cause contrasting RPE abnormalities in mice that correlate with changes in mitochondrial shape and size (overfragmented in TG vs. overfused in mutant). We conclude proper regulation of mitochondrial homeostasis by TMEM135 is critical for RPE health.
Insights
Transmembrane protein 135 (Tmem135) regulates retinal aging and mitochondrial health. Its overexpression causes RPE degeneration, while mutations lead to different abnormalities, highlighting TMEM135
Area of Science:
- Ophthalmology and Vision Science
- Cell Biology
- Aging Research
Background:
- Aging is a primary risk factor for retinal diseases.
- Mechanisms linking aging to ocular homeostasis disruption remain unclear.
- Transmembrane protein 135 (Tmem135) is implicated in retinal aging and mitochondrial dynamics.
Purpose of the Study:
- To investigate the role of Tmem135 in regulating retinal aging and ocular homeostasis in mice.
- To compare the ocular phenotype of mice overexpressing Tmem135 with Tmem135 mutant mice.
Main Methods:
- Eyes from Tmem135 transgenic (TG) and mutant mice were analyzed using histology, immunohistochemistry, and electron microscopy.
- Visual function was assessed via electroretinography (ERG).
- Retinal Pigmented Epithelium (RPE) cultures were used to study mitochondrial morphology.
Main Results:
- Tmem135 TG mice exhibited RPE pathologies including degeneration, vacuolization, and basal laminar deposit formation.
- Reduced mitochondrial number and size were observed in Tmem135 TG RPE.
- ERG amplitudes decreased in aged Tmem135 TG mice, correlating with reduced RPE cell markers; Tmem135 mutant mice showed thicker, smaller, denser RPE cells without degeneration.
Conclusions:
- Tmem135 plays a critical role in maintaining RPE health and mitochondrial homeostasis.
- Both Tmem135 overexpression and mutation lead to distinct RPE abnormalities.
- Mitochondrial morphology (fragmentation in TG, fusion in mutant) is directly impacted by Tmem135 status.
