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Updated: Mar 9, 2026
Methylnitrosourea MNU-induced Retinal Degeneration and Regeneration in the Zebrafish: Histological and Functional Characteristics
Published on: October 20, 2014
Loss of Zebrafish Mfrp Causes Nanophthalmia, Hyperopia, and Accumulation of Subretinal Macrophages
Ross F Collery1, Peter J Volberding1, Jonathan R Bostrom1
1Department of Cell Biology, Neurobiology, and Anatomy, Medical College of Wisconsin, Milwaukee, Wisconsin, United States.
Purpose:
Mutations in membrane frizzled-related protein (MFRP) are associated with nanophthalmia, hyperopia, foveoschisis, irregular patches of RPE atrophy, and optic disc drusen in humans. Mouse mfrp mutants show retinal degeneration but no change in eye size or refractive state. The goal of this work was to generate zebrafish mutants to investigate the loss of Mfrp on eye size and refractive state, and to characterize other phenotypes observed.
Methods:
Clustered regularly interspaced short palindromic repeats (CRISPR)/Cas9 methods were used to generate multiple frameshift mutations in zebrafish mfrp causing premature translational stops in Mfrp. Spectral-domain optical coherence tomography (SD-OCT) was used to measure eye metrics and refractive state, and immunohistochemistry was used to study adult eyes. Gene expression levels were measured using quantitative PCR.
Results:
Zebrafish Mfrp was shown to localize to apical and basal regions of RPE cells, as well as the ciliary marginal zone. Loss of Mfrp in mutant zebrafish was verified histologically. Zebrafish eyes that were mfrp mutant showed reduced axial length causing hyperopia, RPE folding, and macrophages were observed subretinally. Visual acuity was reduced in mfrp mutant animals.
Conclusions:
Mutation of zebrafish mfrp results in hyperopia with subretinal macrophage infiltration, phenocopying aspects of human and mouse Mfrp deficiency. These mutant zebrafish will be useful in studying the onset and progression of Mfrp-related nanophthalmia, the cues that initiate the recruitment of macrophages, and the mechanisms of Mfrp function.
Insights
Zebrafish mfrp mutants exhibit reduced eye size and hyperopia, mimicking human MFRP deficiency. These models aid research into nanophthalmia and related eye conditions.
Area of Science:
- Ophthalmology
- Genetics
- Developmental Biology
Background:
- Mutations in membrane frizzled-related protein (MFRP) are linked to human eye disorders like nanophthalmia and hyperopia.
- Previous studies in mouse models showed retinal degeneration but not significant changes in eye size or refractive state.
Purpose of the Study:
- To create and characterize zebrafish mutants to investigate the role of MFRP in eye size and refractive state.
- To identify other phenotypic consequences of MFRP loss in zebrafish.
Main Methods:
- CRISPR/Cas9 gene editing was employed to generate frameshift mutations in the zebrafish mfrp gene.
- Spectral-domain optical coherence tomography (SD-OCT) was used for eye metric and refractive state measurements.
- Immunohistochemistry and quantitative PCR were utilized to analyze Mfrp localization, RPE structure, and gene expression.
Main Results:
- Zebrafish MFRP localizes to the apical and basal regions of RPE cells and the ciliary marginal zone.
- Mutant zebrafish displayed reduced axial length, leading to hyperopia, RPE folding, and subretinal macrophage infiltration.
- A decrease in visual acuity was observed in the mfrp mutant zebrafish.
Conclusions:
- Zebrafish mfrp mutations result in hyperopia and subretinal macrophage infiltration, phenocopying aspects of human and mouse MFRP deficiency.
- These zebrafish models are valuable for studying the pathogenesis of MFRP-related nanophthalmia and macrophage recruitment.
- The study provides insights into the functional mechanisms of MFRP in ocular development and disease.
