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Pablo Argueso, Ashley M Woodward, Sylvain Lehoux, Flavio Mantelli, Stefano Bonini; Inflammatory stress impairs the N-glycan branching pathway in human ocular surface epithelia.. Invest. Ophthalmol. Vis. Sci. 2018;59(9):3846.
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Regulation of the medial Golgi N-glycan branching pathway is critical for cell growth, arrest, and differentiation. Here, we investigated the effect of inflammation on N-glycosyltransferase expression at the ocular surface.
N-glycans isolated from stratified human corneal epithelial cells were profiled by MALDI-TOF mass spectrometry. The effect of inflammatory mediators on the expression of glycosyltransferases was analyzed using a human glycosylation PCR array and qRT-PCR. Glycosyltransferase activity was determined using UDP-GlcNAc and mannotriose as donor and acceptor substrates, respectively. Impression cytology samples were collected from healthy subjects and patients with ocular cicatricial pemphigoid.
By mass spectrometry, corneal epithelial cells were rich in oligomannose and bi-antennary complex-type N-glycans. Treatment with TNFα resulted in down-regulation of 17 glycosyltransferases involved in N-glycosylation pathways. Of these enzymes, six were involved in the medial Golgi N-glycan branching pathway and included MGAT1 and 2, which are required for the formation of bi-antennary structures. These results were concomitant with reduced ability to transfer GlcNAc to a mannotriose acceptor substrate. Compared to TNFα, IL-1β had a limited effect on glycosyltransferase gene expression. Analysis of ocular pemphigoid tissue revealed a significant decrease in MGAT1 and 2 transcript levels compared to controls.
This study demonstrates that pro-inflammatory conditions lead to alteration of the medial Golgi N-glycan branching pathway, which may have implications to the pathogenesis of ocular surface disease.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.
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