LXR agonist increases apoE secretion from HepG2 spheroid, together with an increased production of VLDL and apoE-rich large HDLReport as inadecuate




LXR agonist increases apoE secretion from HepG2 spheroid, together with an increased production of VLDL and apoE-rich large HDL - Download this document for free, or read online. Document in PDF available to download.

Lipids in Health and Disease

, 10:134

First Online: 05 August 2011Received: 08 July 2011Accepted: 05 August 2011

Abstract

BackgroundThe physiological regulation of hepatic apoE gene has not been clarified, although the expression of apoE in adipocytes and macrophages has been known to be regulated by LXR.

Methods and ResultsWe investigated the effect of TO901317, a LXR agonist, on hepatic apoE production utilizing HepG2 cells cultured in spheroid form, known to be more differentiated than HepG2 cells in monolayer culture. Spheroid HepG2 cells were prepared in alginate-beads. The secretions of albumin, apoE and apoA-I from spheroid HepG2 cells were significantly increased compared to those from monolayer HepG2 cells, and these increases were accompanied by increased mRNA levels of apoE and apoA-I. Several nuclear receptors including LXRα also became abundant in nuclear fractions in spheroid HepG2 cells. Treatment with TO901317 significantly increased apoE protein secretion from spheroid HepG2 cells, which was also associated with the increased expression of apoE mRNA. Separation of the media with FPLC revealed that the production of apoE-rich large HDL particles were enhanced even at low concentration of TO901317, and at higher concentration of TO901317, production of VLDL particles increased as well.

ConclusionsLXR activation enhanced the expression of hepatic apoE, together with the alteration of lipoprotein particles produced from the differentiated hepatocyte-derived cells. HepG2 spheroids might serve as a good model of well-differentiated human hepatocytes for future investigations of hepatic lipid metabolism.

KeywordsSpheroid HepG2 cells LXR agonist Apolipoprotein E ApoE rich HDL VLDL List of AbbreviationsapoA-Iapolipoprotein A-I

apoBapolipoprotein B

apoEapolipoprotein E

TOTO901317

M-HepHepG2 cells cultured in monolayer

S-HepHepG2 cells cultured in spheroidal form

HNFhepatocyte nuclear factor

LXRliver × receptor

PPARperoxisome proliferator-activated receptor

RXRretinoid × receptor

ABCATP-binding cassette transporter

FPLCfast protein liquid chromatography

FBSfetal bovine serum

ELISAenzyme-linked immunosorbent assay.

Electronic supplementary materialThe online version of this article doi:10.1186-1476-511X-10-134 contains supplementary material, which is available to authorized users.

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Author: Makoto Kurano - Naoyuki Iso-O - Masumi Hara - Nobukazu Ishizaka - Kyoji Moriya - Kazuhiko Koike - Kazuhisa Tsukamoto

Source: https://link.springer.com/



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