TY - JOUR
T1 - Mutation in apolipoprotein B associated with hypobetalipoproteinemia despite decreased binding to the low density lipoprotein receptor
AU - Benn, Marianne
AU - Nordestgaard, Børge G
AU - Jensen, Jan Skov
AU - Nilausen, Karin Skov
AU - Meinertz, Hans
AU - Tybjaerg-Hansen, Anne
PY - 2005
Y1 - 2005
N2 - Mutations in apolipoprotein B (APOB) may reduce binding of low density lipoprotein (LDL) to the LDL receptor and cause hypercholesterolemia. We showed that heterozygotes for a new mutation in APOB have hypobetalipoproteinemia, despite a reduced binding of LDL to the LDL receptor. APOB R3480P heterozygotes were identified among 9,255 individuals from the general population and had reduced levels of apoB-containing lipoproteins. Most surprisingly, R3480P LDL bound with lower affinity to the LDL receptor than non-carrier LDL in vitro, and these results were confirmed by turnover studies of LDL in vivo. In very low density lipoprotein (VLDL) turnover studies, the amount of VLDL converted to LDL in R3480P heterozygotes was substantially reduced, suggesting that this was the explanation for the hypobetalipoproteinemia observed in these individuals. Our findings emphasized the importance of combining in vitro studies with both human in vivo and population-based studies, as in vitro studies often have focused on very limited aspects of complex mechanisms taken out of their natural context.
AB - Mutations in apolipoprotein B (APOB) may reduce binding of low density lipoprotein (LDL) to the LDL receptor and cause hypercholesterolemia. We showed that heterozygotes for a new mutation in APOB have hypobetalipoproteinemia, despite a reduced binding of LDL to the LDL receptor. APOB R3480P heterozygotes were identified among 9,255 individuals from the general population and had reduced levels of apoB-containing lipoproteins. Most surprisingly, R3480P LDL bound with lower affinity to the LDL receptor than non-carrier LDL in vitro, and these results were confirmed by turnover studies of LDL in vivo. In very low density lipoprotein (VLDL) turnover studies, the amount of VLDL converted to LDL in R3480P heterozygotes was substantially reduced, suggesting that this was the explanation for the hypobetalipoproteinemia observed in these individuals. Our findings emphasized the importance of combining in vitro studies with both human in vivo and population-based studies, as in vitro studies often have focused on very limited aspects of complex mechanisms taken out of their natural context.
U2 - http://dx.doi.org/10.1074/jbc.M413877200
DO - http://dx.doi.org/10.1074/jbc.M413877200
M3 - Journal article
VL - 280
SP - 21052
EP - 21060
JO - Journal of Biological Chemistry
JF - Journal of Biological Chemistry
SN - 0021-9258
IS - 22
ER -