An NPC1L1 gene promoter variant is associated with autosomal dominant hypercholesterolemia

Martín, B.; Solanas-Barca, M.; García-Otín, Á.-L.; Pampín, S.; Cofán, M.; Ros, E.; Rodríguez-Rey, J.-C.; Pocoví, M.; Civeira, F.

doi:10.1016/j.numecd.2009.03.023

« Previous Next »Nutrition, Metabolism & Cardiovascular Diseases
Volume 20, Issue 4 , Pages 236-242, May 2010

An NPC1L1 gene promoter variant is associated with autosomal dominant hypercholesterolemia

B. Martín
- Departamento de Bioquímica y Biología Molecular y Celular, Universidad de Zaragoza, and Ciber Enfermedades Raras (CIBERER), Instituto de Salud Carlos III (ISCIII), Spain
M. Solanas-Barca
- Laboratorio de Investigación Molecular, Hospital Universitario Miguel Servet, I+CS, Zaragoza, Spain
Á.-L. García-Otín
- Laboratorio de Investigación Molecular, Hospital Universitario Miguel Servet, I+CS, Zaragoza, Spain
S. Pampín
- Departamento de Biología Molecular, Facultad de Medicina, Universidad de Cantabria, Santander, Spain
M. Cofán
- Unitat de Lípids, Servei d'Endocrinologia i Nutrició, Institut d'Investigacions Biomèdiques August Pi i Sunyer, Hospital Clínic, Barcelona and Ciber Fisiopatología de la Obesidad y Nutrición (CIBEROBN), ISCIII, Spain
E. Ros
- Unitat de Lípids, Servei d'Endocrinologia i Nutrició, Institut d'Investigacions Biomèdiques August Pi i Sunyer, Hospital Clínic, Barcelona and Ciber Fisiopatología de la Obesidad y Nutrición (CIBEROBN), ISCIII, Spain
J.-C. Rodríguez-Rey
- Departamento de Biología Molecular, Facultad de Medicina, Universidad de Cantabria, Santander, Spain
M. Pocoví
- Departamento de Bioquímica y Biología Molecular y Celular, Universidad de Zaragoza, and Ciber Enfermedades Raras (CIBERER), Instituto de Salud Carlos III (ISCIII), Spain
F. Civeira
- Laboratorio de Investigación Molecular, Hospital Universitario Miguel Servet, I+CS, Zaragoza, Spain
- Corresponding author. Laboratorio de Investigación Molecular, Hospital Universitario Miguel Servet, Avda. Isabel La Católica, 1-3, 50009 Zaragoza, Spain. Tel.: +34 976765500; fax: +34 976369985.

Received 25 November 2008; received in revised form 19 March 2009; accepted 20 March 2009. published online 14 September 2009.

Abstract

Background and aims

A substantial number of subjects with autosomal dominant hypercholesterolemia (ADH) do not have LDL receptor (LDLR) or apolipoprotein B (APOB) mutations. Some ADH subjects appear to hyperabsorb sterols from the intestine, thus we hypothesized that they could have variants of the Niemann–Pick C1-Like 1 gene (NPC1L1). NPC1L1 encodes a crucial protein involved in intestinal sterol absorption.

Methods and results

Four NPC1L1 variants (−133A>G, −18C>A, 1679C>G, 28650A>G) were analyzed in 271 (155 women and 116 men) ADH bearers without mutations in LDLR or APOB aged 30–70years and 274 (180 women and 94 men) control subjects aged 25–65years. The AC haplotype determined by the −133A>G and −18C>A variants was underrepresented in ADH subjects compared to controls (p=0.01). In the ADH group, cholesterol absorption/synthesis markers were significantly lower in AC homozygotes that in all others haplotypes. Electrophoretic mobility shift assay (EMSA) results revealed that the −133A-specific oligonucleotide produced a retarded band stronger than the −133G allele. Luciferase activity with NPC1L1 −133G variant was 2.5-fold higher than with the −133A variant.

Conclusion

The −133A>G polymorphism exerts a significant effect on NPC1L1 promoter activity. NPC1L1 promoter variants might explain in part the hypercholesterolemic phenotype of some subjects with nonLDLR/nonAPOB ADH.

Keywords: Familial hypercholesterolemia, Polymorphisms, Cholesterol intestinal absorption

Abbreviations: ADH, autosomal dominant hypercholesterolemia, LDLR, LDL receptor gene, APOB, apolipoprotein B gene, NPC1L1, Niemann-Pick C1-Like 1, EMSA, electrophoretic mobility shift assay, CVD, cardiovascular disease, Apo, apolipoprotein, FH, familial hypercholesterolemia, FDB, familial defective apolipoprotein B, LDL, low-density lipoprotein, HDL, high-density lipoprotein, SNP, single nucleotide polymorphism, DNA, deoxyribonucleic acid, bp, base pair, PCR, polymerase chain reaction, IR, interquartile range