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ABCC6- a new player in cellular cholesterol and lipoprotein metabolism?

Patricia Kuzaj1, Joachim Kuhn1, Mareike Dabisch-Ruthe1, Isabel Faust1, Christian Götting2, Cornelius Knabbe1 and Doris Hendig1*

Author Affiliations

1 Herz- und Diabeteszentrum NRW, Institut für Laboratoriums- und Transfusionsmedizin, Universitätsklinik der Ruhr-Universität Bochum, Georgstraße 11, 32 545 Bad Oeynhausen, Germany

2 MVZ Labor Limbach Nürnberg, Lina-Ammon-Straße 28, 90471 Nürnberg, Germany

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Lipids in Health and Disease 2014, 13:118  doi:10.1186/1476-511X-13-118

Published: 27 July 2014



Dysregulations in cholesterol and lipid metabolism have been linked to human diseases like hypercholesterolemia, atherosclerosis or the metabolic syndrome. Many ABC transporters are involved in trafficking of metabolites derived from these pathways. Pseudoxanthoma elasticum (PXE), an autosomal-recessive disease caused by ABCC6 mutations, is characterized by atherogenesis and soft tissue calcification.


In this study we investigated the regulation of cholesterol biosynthesis in human dermal fibroblasts from PXE patients and healthy controls.


Gene expression analysis of 84 targets indicated dysregulations in cholesterol metabolism in PXE fibroblasts. Transcript levels of ABCC6 were strongly increased in lipoprotein-deficient serum (LPDS) and under serum starvation in healthy controls. For the first time, increased HMG CoA reductase activities were found in PXE fibroblasts. We further observed strongly elevated transcript and protein levels for the proprotein convertase subtilisin/kexin type 9 (PCSK9), as well as a significant reduction in APOE mRNA expression in PXE.


Increased cholesterol biosynthesis, elevated PCSK9 levels and reduced APOE mRNA expression newly found in PXE fibroblasts could enforce atherogenesis and cardiovascular risk in PXE patients. Moreover, the increase in ABCC6 expression accompanied by the induction of cholesterol biosynthesis supposes a functional role for ABCC6 in human lipoprotein and cholesterol homeostasis.

Pseudoxanthoma elasticum; ABC transporter; ABCC6; Cholesterol biosynthesis; Atherosclerosis; HMG CoA reductase; SREBP2; PCSK9; LDLR; APOE