TY - JOUR
T1 - Site-specific O-glycosylation of members of the low-density lipoprotein receptor superfamily enhances ligand interactions
AU - Wang, Shengjun
AU - Mao, Yang
AU - Narimatsu, Yoshiki
AU - Ye, Zilu
AU - Tian, Weihua
AU - Goth, Christoffer K
AU - Lira-Navarrete, Erandi
AU - Pedersen, Nis B
AU - Benito-Vicente, Asier
AU - Martin, Cesar
AU - Uribe, Kepa B
AU - Hurtado-Guerrero, Ramon
AU - Christoffersen, Christina
AU - Seidah, Nabil G
AU - Nielsen, Rikke
AU - Christensen, Erik I
AU - Hansen, Lars
AU - Bennett, Eric P
AU - Vakhrushev, Sergey Y
AU - Schjoldager, Katrine T
AU - Clausen, Henrik
N1 - © 2018 by The American Society for Biochemistry and Molecular Biology, Inc.
PY - 2018/5/11
Y1 - 2018/5/11
N2 - The low-density lipoprotein receptor (LDLR) and related receptors are important for the transport of diverse biomolecules across cell membranes and barriers. Their functions are especially relevant for cholesterol homeostasis and diseases, including neurodegenerative and kidney disorders. Members of the LDLR-related protein family share LDLR class A (LA) repeats providing binding properties for lipoproteins and other biomolecules. We previously demonstrated that short linker regions between these LA repeats contain conserved O-glycan sites. Moreover, we found that O-glycan modifications at these sites are selectively controlled by the GalNAc-transferase isoform, GalNAc-T11. However, the effects of GalNAc-T11-mediated O-glycosylation on LDLR and related receptor localization and function are unknown. Here, we characterized O-glycosylation of LDLR-related proteins and identified conserved O-glycosylation sites in the LA linker regions of VLDLR, LRP1, and LRP2 (Megalin) from both cell lines and rat organs. Using a panel of gene-edited isogenic cell line models, we demonstrate that GalNAc-T11-mediated LDLR and VLDLR O-glycosylation is not required for transport and cell-surface expression and stability of these receptors but markedly enhances LDL and VLDL binding and uptake. Direct ELISA-based binding assays with truncated LDLR constructs revealed that O-glycosylation increased affinity for LDL by ∼5-fold. The molecular basis for this observation is currently unknown, but these findings open up new avenues for exploring the roles of LDLR-related proteins in disease.
AB - The low-density lipoprotein receptor (LDLR) and related receptors are important for the transport of diverse biomolecules across cell membranes and barriers. Their functions are especially relevant for cholesterol homeostasis and diseases, including neurodegenerative and kidney disorders. Members of the LDLR-related protein family share LDLR class A (LA) repeats providing binding properties for lipoproteins and other biomolecules. We previously demonstrated that short linker regions between these LA repeats contain conserved O-glycan sites. Moreover, we found that O-glycan modifications at these sites are selectively controlled by the GalNAc-transferase isoform, GalNAc-T11. However, the effects of GalNAc-T11-mediated O-glycosylation on LDLR and related receptor localization and function are unknown. Here, we characterized O-glycosylation of LDLR-related proteins and identified conserved O-glycosylation sites in the LA linker regions of VLDLR, LRP1, and LRP2 (Megalin) from both cell lines and rat organs. Using a panel of gene-edited isogenic cell line models, we demonstrate that GalNAc-T11-mediated LDLR and VLDLR O-glycosylation is not required for transport and cell-surface expression and stability of these receptors but markedly enhances LDL and VLDL binding and uptake. Direct ELISA-based binding assays with truncated LDLR constructs revealed that O-glycosylation increased affinity for LDL by ∼5-fold. The molecular basis for this observation is currently unknown, but these findings open up new avenues for exploring the roles of LDLR-related proteins in disease.
U2 - 10.1074/jbc.M117.817981
DO - 10.1074/jbc.M117.817981
M3 - Journal article
C2 - 29559555
SN - 0021-9258
VL - 293
SP - 7408
EP - 7422
JO - Journal of Biological Chemistry
JF - Journal of Biological Chemistry
IS - 19
ER -