Two novel D151Y and M391T LDLR mutations causing LDLR transport defects in Thai patients with familial hypercholesterolemia.
BACKGROUND
Familial hypercholesterolemia (FH) is an autosomal dominant disorder caused by mutations in the low density lipoprotein receptor (LDLR) gene. Two novel LDLR mutations, D151Y and M391T, had been previously identified in unrelated Thai patients with heterozygous FH. To confirm that these mutations cause FH, the functional characteristics of D151Y and M391T, which are located in the fourth cysteine repeat of the ligand-binding domain and in the sixth YWTD repeat of the epidermal growth factor precursor homology domain, respectively, were studied.


METHODS
CHO-ldlA7 cells were transfected with wild type and mutant LDLR cDNAs. Thereafter, the localization, expression, and ability of LDL uptake of LDLR were evaluated by confocal laser scanning microscope (CLSM), and flow cytometry.


RESULTS
CLSM revealed both D151Y and M391T LDLR were partially retained in the endoplasmic reticulum, with the remaining residual activity observed by LDL uptake. Similarly, flow cytometric analysis showed a significant reduction of LDLR expression to 18% and 38% and of LDL uptake to 15% and 71% in D151Y and M391T LDLR, respectively.


CONCLUSIONS
The transport defect of LDLR contributes to the pathology of FH. These data are useful for an insight inspires the development of novel lipid-lowering drugs with beneficial therapeutic value.
Jeenduang
Nutjaree
N
Department of Clinical Chemistry, Faculty of Medical Technology, Mahidol University, Bangkok, Thailand.
Ruangpracha
Athisake
A
Promptmas
Chamras
C
Pongrapeeporn
Klai-upsorn S
KU
Porntadavity
Sureerut
S
D000818:Animals; D001692:Biological Transport / Q000235:genetics; D002460:Cell Line; D004721:Endoplasmic Reticulum; D006801:Humans; D006937:Hypercholesterolemia / Q000235:genetics*; D008077:Lipoproteins, LDL / Q000378:metabolism; D020125:Mutation, Missense; D011973:Receptors, LDL / Q000032:analysis / Q000235:genetics* / Q000378:metabolism; D013785:Thailand; D014162:Transfection
D008077:Lipoproteins, LDL; D011973:Receptors, LDL