Biochemical and Biophysical Research Communications, Vol.479, No.4, 628-635, 2016
Identification and characterization of NPC1L1 variants in Uygur and Kazakh with extreme low-density lipoprotein cholesterol
Background: Plasma levels of low-density lipoprotein cholesterol (LDL-C) are a major risk factor for cardiovascular disease and are influenced by both heredity and dietary habits. The Niemann-Pick Cl like 1 (NPC1L1) protein mediates efficient dietary cholesterol absorption and contributes to variations in human LDL-C levels. Methods: In the present study, using high throughput sequencing we identified three non-synonymous (NS) variations and 64 synonymous variations in the NPC1L1 gene from subsets of Chinese Han, Uygur and Kazakh populations with high or low LDL-C. Subsequently, three NS variations encoding R174H, V177I and V1284L substitutions were observed only in Uygur and Kazakh individuals with limited maximal plasma LDL-C levels. Results: In further experiments, we investigated cholesterol-regulated recycling and glycosylation and stability of these NS NPC1L1 variants. However, no significant differences between WT and variant NPC1L1 proteins were observed using in vivo assays in mouse livers with adenovirus-mediated expression, demonstrating that none of the three NPC1L1 NS variants caused decreased uptake of biliary cholesterol. Conclusions: Simultaneously, these data indicate that R174H, V177I and V1284L NPC1L1 variations in high or low LDL-C individuals may not directly influence cholesterol absorption by NPC1L1. (C) 2016 Published by Elsevier Inc.