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Updated: May 27, 2026
Efficient Dissection and Culture of Primary Mouse Retinal Pigment Epithelial Cells
Published on: February 10, 2021
PALS1 is essential for retinal pigment epithelium structure and neural retina stratification
Bokyung Park1, Celso Henrique Alves, Ditte M Lundvig
1Department of Neuromedical Genetics, The Netherlands Institute for Neuroscience, Royal Netherlands Academy of Arts and Sciences, 1105 BA Amsterdam, The Netherlands.
Insights
Membrane-associated palmitoylated protein 5 (MPP5 or PALS1) deficiency causes retinal degeneration. PALS1 is crucial for photoreceptor-Müller glia adhesion and retinal development, impacting retinal pigment epithelium and neural retina.
Area of Science:
- Ophthalmology
- Cell Biology
- Genetics
Background:
- The PALS1-CRB-MUPP1 scaffold organizes cell adhesion in the retina.
- CRB1 mutations cause retinitis pigmentosa and Leber congenital amaurosis, but genotype-phenotype correlations are unclear.
- Other Crumbs complex proteins may modulate disease severity.
Purpose of the Study:
- To investigate the physiological role of PALS1 in retinal development and function.
- To understand PALS1's contribution to photoreceptor-Müller glia cell adhesion.
- To explore PALS1's influence on retinal disease progression.
Main Methods:
- Generation and analysis of conditional knockdown mice for Pals1.
- Confocal scanning laser ophthalmoscopy and spectral domain optical coherence tomography for retinal imaging.
- Electroretinography and histological analysis to assess retinal structure and function.
Main Results:
- PALS1 deficiency led to retinal abnormalities, including ectopic photoreceptor nuclei and irregular outer limiting membrane.
- Progressive photoreceptor degeneration was indicated by attenuated electroretinography a- and b-waves.
- Reduced Crumbs complex proteins, gliosis, and persistent cell death were observed in PALS1-deficient retinas.
Conclusions:
- PALS1 plays a critical role in retinal pigment epithelium and neural retina.
- PALS1 is essential for proper photoreceptor-Müller glia adhesion and retinal development.
- PALS1 deficiency results in progressive retinal degeneration, highlighting its importance in maintaining retinal integrity.
Abstract:
The membrane-associated palmitoylated protein 5 (MPP5 or PALS1) is thought to organize intracellular PALS1-CRB-MUPP1 protein scaffolds in the retina that are involved in maintenance of photoreceptor-Müller glia cell adhesion. In humans, the Crumbs homolog 1 (CRB1) gene is mutated in progressive types of autosomal recessive retinitis pigmentosa and Leber congenital amaurosis. However, there is no clear genotype-phenotype correlation for CRB1 mutations, which suggests that other components of the CRB complex may influence the severity of retinal disease. Therefore, to understand the physiological role of the Crumbs complex proteins, especially PALS1, we generated and analyzed conditional knockdown mice for Pals1. Small irregularly shaped spots were detected throughout the PALS1 deficient retina by confocal scanning laser ophthalmoscopy and spectral domain optical coherence tomography. The electroretinography a- and b-wave was severely attenuated in the aged mutant retinas, suggesting progressive degeneration of photoreceptors. The histological analysis showed abnormal retinal pigment epithelium structure, ectopic photoreceptor nuclei in the subretinal space, an irregular outer limiting membrane, half rosettes of photoreceptors in the outer plexiform layer, and a thinner photoreceptor synaptic layer suggesting improper photoreceptor cell layering during retinal development. The PALS1 deficient retinas showed reduced levels of Crumbs complex proteins adjacent to adherens junctions, upregulation of glial fibrillary acidic protein indicative of gliosis, and persisting programmed cell death after retinal maturation. The phenotype suggests important functions of PALS1 in the retinal pigment epithelium in addition to the neural retina.
