St3gal6 and
St6gal1. Increased percentages of core-fucosylated and triantennary glycan moieties were seen in LDKO livers, and proteins with the “hyperglycoforms” preferentially localized to exosomes and lysosomes. This up-regulation of N-glycosylation machinery was specific to the Golgi apparatus and not the endoplasmic reticulum. The increased glycan complexity in the LDKO correlated well with dilated unstacked Golgi ribbons and alterations in the secretion of albumin, cholesterol, and triglycerides. Our findings demonstrate a role for the FXR-SHP axis in maintaining glycoprotein diversity in the liver.
INTRODUCTION
N-Glycosylation is a key posttranslational modification that decides the fate of several liver proteins, including their targeting to the plasma membrane or for secretion. Briefly, various combinations of sugar molecules (glycan moieties) attach covalently to the nitrogen of asparagine residues of a protein (