Blockade of the neuropeptide Y Y2 receptor with the potent antagonist BIIE0246 regulates gene expression levels in the lipid metabolic pathways in human hepatoma cell line HepG2

Abstract

Neuropeptide Y (NPY) and NPY Y2 receptor (Y2R) is involved in the stress-induced visceral obesity in mice. We have previously reported the association between 5'-flanking region of Y2R gene SNPs and plasma HDL-cholesterol levels in healthy subjects. Plasma HDL-cholesterol levels were significantly different in subjects with each SNPs (rs6857530; GG<GA<AA or rs6857715; TT<TC<CC). The luciferase activity was detected in HepG2 but not in macrophage differentiated from THP-1 cells when used pGL3-Basic vector including 5'-flanking region of Y2R gene with rs6857530GG plus rs6857715TT. The aim of the study is to elucidate further the mechanism underlying the association between Y2R gene SNPs and plasma HDL-cholesterol levels. After confirming that the sequences of the 5'-flanking region of Y2R gene included heterozygous rs6857530 (G/A) and rs6857715 (T/C) in HepG2 cells, we compared the effect of NPY alone and NPY plus Y2R antagonist BIIE0246 on gene expression in cultured HepG2 cells using real-time reverse transcription PCR (real-time RT-PCR) and microarray. BIIE0246 addition to HepG2 cells failed to change the mRNA expression levels of representative HDL metabolic regulators such as apo-lipoprotein A1 by real-time RT-PCR. BIIE0246 up-regulated (>1.5-fold) 743 entities, and down-regulated (<0.67-fold) 492 entities of 54,675 probe sets. BIIE0246-upregulated genes significantly (P-value<0.001) related to gene ontology (GO) categories of 3 biological processes, 7 cellular components and 1 molecular function. Three biological processes were chylomicron remodeling, negative regulation of cholesterol and sterol transport. BIIE0246-downregulated genes significantly related to GO categories of 44 biological processes, 11 cellular components and 1 molecular function. Furthermore, BIIE0246-downregulated genes were significantly involved in 44 pathways (P<0.01), in which sterol responsive element binding protein signaling were included. BIIE0246-upregulated genes were significantly involved in 22 pathways including vitamin B12/ lipoprotein metabolism (P=0.0048). These results suggest that Y2R blockade might inhibit cholesterol synthesis and raise plasma HDL-cholesterol levels, suggesting a new therapeutic drug for dyslipidemia in subjects with specific Y2R SNPs.