Expression and cell compartmentalization of EGF–containing extracellular matrix protein 1 in retinal cells

Abstract

Abstract: : Purpose:A single missense mutation in EGF–containing extracellular matrix protein 1 ( EFEMP1 ) is assiociated with Malattia Leventinese ( ML ), an inherited macular degenerative disease. Wild type protein is know to be secreated whereas mutant is misfolded and retained within cells. Cells expressing EFEMP1 gene have not been identified so our purpose was to study the expression pattern and the cell compartmentalization of EFEMP1 proteins. As mutation may alter secretion of this protein we compared cell compartmentalization of normal and mutated proteins. Methods:To determine expression patterns of the EFEMP1 gene, in situ hybridization studies were carried out on paraffine sections of normal and disease ( ML and age–related macular degeneration: AMD ) human retinas. Fusion proteins using either GFP or a C terminal flag were constructed in order to determine cellular localization of the protein. Results:In normal eye EFEMP1 transcripts are localized mainly in the retinal ganglion cells and the photoreceptors. In the diseased human eye, transcripts are principally found in the RPE accompanied with drastic morphological changes of this tissue. Fusion proteins in cell lines are localized in different compartments of the secretory pathways. Conclusions:Morphological alterations of RPE cells in ML eye coincide with significant changes in the expression pattern of the EFEMP1 gene.

Keywords: retinal degenerations: cell biology • in situ hybridization • gene/expression