Profound Re-Organization of Cell Surface Proteome in Equine Retinal Pigment Epithelial Cells in Response to In Vitro Culturing

Szober, Christoph M.; Hauck, Stefanie M.; Euler, Kerstin N.; Fröhlich, Kristina J. H.; Alge-Priglinger, Claudia S.; Ueffing, Marius; Deeg, Cornelia A.

doi:10.3390/ijms131114053

Cited by 7 publications

(5 citation statements)

References 41 publications

(60 reference statements)

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“…Since exogenous Gal-3 bound to the ECM of PVR membranes, and both CD147 and integrin-β1 could be detected in human specimen of PVR, this interaction could be of relevance in the clinical situation. Although not investigated at this point, the activity profile of the three interacting proteins identified here, together with the increased expression of Gal-3 upon RPE dedifferentiation [29], [76], would fit well into the theme of the pathogenesis of the disease. As compared with other mechanisms for affinity/avidity regulation, glycan-protein interactions may be particularly well suited for mediating the prolonged changes in cell behavior that accompany profound phenotypic alterations such as those observed during epithelial-to-mesenchymal transition of the RPE in PVR.…”

Section: Discussionmentioning

confidence: 64%

Galectin-3 Induces Clustering of CD147 and Integrin-β1 Transmembrane Glycoprotein Receptors on the RPE Cell Surface

et al. 2013

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Proliferative vitreoretinopathy (PVR) is a blinding disease frequently occurring after retinal detachment surgery. Adhesion, migration and matrix remodeling of dedifferentiated retinal pigment epithelial (RPE) cells characterize the onset of the disease. Treatment options are still restrained and identification of factors responsible for the abnormal behavior of the RPE cells will facilitate the development of novel therapeutics. Galectin-3, a carbohydrate-binding protein, was previously found to inhibit attachment and spreading of retinal pigment epithelial cells, and thus bares the potential to counteract PVR-associated cellular events. However, the identities of the corresponding cell surface glycoprotein receptor proteins on RPE cells are not known. Here we characterize RPE-specific Gal-3 containing glycoprotein complexes using a proteomic approach. Integrin-β1, integrin-α3 and CD147/EMMPRIN, a transmembrane glycoprotein implicated in regulating matrix metalloproteinase induction, were identified as potential Gal-3 interactors on RPE cell surfaces. In reciprocal immunoprecipitation experiments we confirmed that Gal-3 associated with CD147 and integrin-β1, but not with integrin-α3. Additionally, association of Gal-3 with CD147 and integrin-β1 was observed in co-localization analyses, while integrin-α3 only partially co-localized with Gal-3. Blocking of CD147 and integrin-β1 on RPE cell surfaces inhibited binding of Gal-3, whereas blocking of integrin-α3 failed to do so, suggesting that integrin-α3 is rather an indirect interactor. Importantly, Gal-3 binding promoted pronounced clustering and co-localization of CD147 and integrin-β1, with only partial association of integrin-α3. Finally, we show that RPE derived CD147 and integrin-β1, but not integrin-α3, carry predominantly β-1,6-N-actyl-D-glucosamine-branched glycans, which are high-affinity ligands for Gal-3. We conclude from these data that extracellular Gal-3 triggers clustering of CD147 and integrin-β1 via interaction with β1,6-branched N-glycans on RPE cells and hypothesize that Gal-3 acts as a positive regulator for CD147/integrin-β1 clustering and therefore modifies RPE cell behavior contributing to the pathogenesis of PVR. Further investigations at this pathway may aid in the development of specific therapies for PVR.

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Section: Discussionmentioning

confidence: 64%

Galectin-3 Induces Clustering of CD147 and Integrin-β1 Transmembrane Glycoprotein Receptors on the RPE Cell Surface

et al. 2013

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“…Although these findings shed more light on disease mechanisms, the interaction of these dysfunctional molecular mechanisms driving ERU as well as their exact individual role and timing in ERU pathogenesis needs further assessment. Establishment of a Mueller glia cell line ( 133 ) and characterization of cultured RPE cells ( 90 ) provide valuable tools for more in depth functional examinations of ERU pathology. Additionally, the possibility of commensal microbiota involvement in ERU onset needs to be addressed.…”

Section: Discussionmentioning

confidence: 99%

“…The outer BRB is formed by retinal pigment epithelium (RPE) cells, which play a crucial role in the mainly avascular retina of the horse, since they maintain homeostasis of retinal cells ( 89 ). This is also reflected in the RPE surface proteome, which strongly associates to transport processes ( 90 ). Furthermore, horses with ERU display a distinctly changed RPE membrane protein repertoire in ERU ( 91 ).…”

Section: Target Organmentioning

confidence: 99%

Immunological Insights in Equine Recurrent Uveitis

Degroote¹,

Deeg²

2021

Front. Immunol.

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Horses worldwide suffer from equine recurrent uveitis (ERU), an organ-specific, immune-mediated disease with painful, remitting-relapsing inflammatory attacks alternating with periods of quiescence, which ultimately leads to blindness. In course of disease, both eyes can eventually be affected and since blind horses pose a threat to themselves and their surroundings, these animals have to be killed. Therefore, this disease is highly relevant for veterinary medicine. Additionally, ERU shows strong clinical and pathological resemblance to autoimmune uveitis in man. The exact cause for the onset of ERU is unclear to date. T cells are believed to be the main effector cells in this disease, as they overcome the blood retinal barrier to invade the eye, an organ physiologically devoid of peripheral immune cells. These cells cause severe intraocular inflammation, especially in their primary target, the retina. With every inflammatory episode, retinal degeneration increases until eyesight is completely lost. In ERU, T cells show an activated phenotype, with enhanced deformability and migration ability, which is reflected in the composition of their proteome and downstream interaction pathways even in quiescent stage of disease. Besides the dysregulation of adaptive immune cells, emerging evidence suggests that cells of the innate immune system may also directly contribute to ERU pathogenesis. As investigations in both the target organ and the periphery have rapidly evolved in recent years, giving new insights on pathogenesis-associated processes on cellular and molecular level, this review summarizes latest developments in ERU research.

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“…Retinal pigment epithelium (RPE) builds the outer blood-retinal barrier [ 6 ] and is the crucial part of the immune defense of the eye [ 7 ]. We started with in-depth molecular analysis of RPE cells by creating an equine cell line and comparing the cell surface proteome of Passage 4 equine RPE cells and native cells [ 6 ]. Since there was a significant alteration between cell surface proteomes of native and cultured cells, the suitability of cultured cells for molecular analyses was affected [ 6 ].…”

Section: Introductionmentioning

confidence: 99%

“…We started with in-depth molecular analysis of RPE cells by creating an equine cell line and comparing the cell surface proteome of Passage 4 equine RPE cells and native cells [ 6 ]. Since there was a significant alteration between cell surface proteomes of native and cultured cells, the suitability of cultured cells for molecular analyses was affected [ 6 ]. Thus, in a follow-up study, we used in situ labelling of tissue samples in very short post-mortem times, which enabled the identification of 148 RPE cell surface proteins, potentially representing their appearance in physiological and pathophysiological in vivo processes [ 5 ].…”

Section: Introductionmentioning

confidence: 99%

Novel Localization of Peripherin 2, the Photoreceptor-Specific Retinal Degeneration Slow Protein, in Retinal Pigment Epithelium

Uhl

Amann

Hauck

et al. 2015

IJMS

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Retinal pigment epithelium (RPE) builds the outer blood-retinal barrier of the eye. Since one typical feature of the autoimmune disease, equine recurrent uveitis (ERU), is the breakdown of this barrier, we recently performed comparative analysis of healthy and uveitic RPE. We identified for the first time peripherin 2, which is responsible for visual perception and retina development, to be localized in RPE. The purpose of this study was therefore to validate our findings by characterizing the expression patterns of peripherin 2 in RPE and retina. We also investigated whether peripherin 2 expression changes in ERU and if it is expressed by the RPE itself. Via immunohistochemistry, significant downregulation of peripherin 2 in uveitic RPE compared to the control was detectable, but there was no difference in healthy and uveitic retina. A further interesting finding was the clear distinction between peripherin 2 and the phagocytosis marker, rhodopsin, in healthy RPE. In conclusion, changes in the expression pattern of peripherin 2 selectively affect RPE, but not retina, in ERU. Moreover, peripherin 2 is clearly detectable in healthy RPE due to both phagocytosis and the expression by the RPE cells themselves. Our novel findings are very promising for better understanding the molecular mechanisms taking place on RPE in uveitis.

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Profound Re-Organization of Cell Surface Proteome in Equine Retinal Pigment Epithelial Cells in Response to In Vitro Culturing

Cited by 7 publications

References 41 publications

Galectin-3 Induces Clustering of CD147 and Integrin-β1 Transmembrane Glycoprotein Receptors on the RPE Cell Surface

Galectin-3 Induces Clustering of CD147 and Integrin-β1 Transmembrane Glycoprotein Receptors on the RPE Cell Surface

Immunological Insights in Equine Recurrent Uveitis

Novel Localization of Peripherin 2, the Photoreceptor-Specific Retinal Degeneration Slow Protein, in Retinal Pigment Epithelium

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