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P. Yang, J. Tyrrell, G. J. Jaffe; Expression and Distribution of Membrane Complement Regulatory Proteins in the Mouse Posterior Segment. Invest. Ophthalmol. Vis. Sci. 2008;49(13):5167.
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There is increasing evidence that complement and inflammation contribute to age-related macular degeneration (AMD). Membrane complement regulatory proteins (mCRPs) such as complement receptor 1-related gene/protein (crry), a rodent-specific human CD46 analog, decay accelerating factor (DAF, CD55), and membrane inhibitor of reactive lysis (MIRL, CD59), protect cells from complement-mediated injury. The expression of mouse and human mCRPs differ in non-ocular tissues. To determine the function of these molecules in mouse models of AMD, it is important to understand their distribution and function in the mouse ocular tissues. Herein, we characterized the expression and distribution of mCRPS in the mouse posterior segment.
CD55, CD59, and crry mRNA and protein expression from C57Bl/6 (WT) and CD55/59 double knockout (CD55-/-CD59-/-) mice were determined by real-time RT-PCR, Western blot, and immunohistochemistry. Testis and kidney from WT and CD55-/-CD59-/- mice were used as positive controls. Staining of phosphatidylinositol-specific phospholipase C (PIPLC)-treated unfixed and fixed frozen sections were compared under identical conditions to assess release of glycosylphosphatidylinositol (GPI)-anchored CD59a from retinal tissue.
In WT mice, CD59a mRNA and protein were more abundant in eyecups compared to testis and kidney. CD59a mRNA and protein were not detected in tissues of CD55-/-CD59-/- mice. CD59a was distributed in photoreceptors and the outer plexiform layers of WT mice, but were not detected in CD55-/-CD59-/- retina. PIPLC treatment reduced CD59a WT mouse expression. CD55 mRNA and protein were only detected in WT testis but not WT ocular tissue or CD55-/-CD59 ocular tissue or testis. Crry was observed in WT mouse ocular tissues at higher levels than in WT testis, and at even higher levels in CD55-/-CD59-/- ocular tissue. Crry was localized to ganglion cell layer, inner nuclear layer and outer plexiform layer.
mCRPs are abundantly expressed in mouse posterior segment and likely protect these tissues from complement attack. These data will be useful to design and evaluate mouse models of AMD.
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