Figure 2.
The GlcNAc-branching pathway in ocular surface epithelia. a, branches in complex-type N-glycans are processed through a series of enzymes, including MGAT1, MAN2A1, MAN2A2, MGAT2, MGAT4A, MGAT4B, and MGAT5 in the medial Golgi compartment. Gene expression of all of these enzymes was confirmed by qPCR in stratified human corneal and conjunctival cell lines, primary corneal epithelial cells, and native tissue (impression cytology) from human conjunctiva. b, the expression of N-glycan-processing genes in stratified cultures of human corneal epithelial cells was assessed by qPCR using a human glycosylation PCR array. The data show expression of B4GALT1 and B3GNT8, enzymes involved in the synthesis of poly-N-acetyllactosamine. In these experiments, negative or positive ΔΔCT values indicate, respectively, whether expression of the gene of interest is higher or lower than the reference gene MGAT1. Results in a represent three independent experiments performed in duplicate or triplicate. Data are represented as the mean ± S.D. Significance was determined using one-way analysis of variance with Tukey's post hoc test. The array in b was repeated twice with independently isolated RNA pooled from three tissue culture plates. *, p < 0.05; **, p < 0.01; ns, nonsignificant. GalT, galactosyltransferase.