Mechanism of lacritin-dependent production of the important dry eye mucin 'MUC16'. Homo sapiens

Lacritin targets its coreceptor 'syndecan-1' in lacritin-dependent production of the important dry eye mucin 'MUC16'. Real-time PCR analysis suggests that this effect is post-transcriptional. In contrast, serum stimulation of MUC16 by these cells is transcriptionally dependent. Our goal is to determine whether this regulation is global to other heavily O-glycosylated proteins, and if so, if it is dependent on transcription of a Golgi glycosyltransferases. If not, the mechanism might be microRNA dependent. Overall design: Among other glycogenes, expression of heparanases, sulfotransferases and epimerase are also of interest. Heparanase is required for lacritin binding to its co-receptor syndecan-1 and this binding site may require a sulfated iduronic acid. In request 1705, we recently asked core D whether they could generate this sulfate iduronic acid-containing glycan (iduronic acid (2-O-sulfated)-N-acetylglucosamine-glucuronic acid-N-acetylglucosamine-[glucuronic acid-N-acetylglucosamine]5-glucuronic acid-galactose-galactose-SERINE) to test as a competitive inhibitor in binding studies. Our experiment is to compare Glyco-gene expression by human corneal epithelial cells in response to cell communication glycoprotein 'lacritin' versus negative control deletion construct 'C-25 lacritin' and versus positive control serum.