Pre- and postnatal hepatic expression profiles of two pig breeds differing in body composition

In order to gain insight into hepatic metabolic pathways and key transcripts affecting traits related to body composition we aimed to compare samples of pigs of two breeds, the “obese” German Landrace (DL) and the “lean” Pietrain (Pi) obtained at prenatal stages (35, 63, and 91 days post conceptionem) and at adult age (180 days). In terms of number of genes regulated the most striking differences between DL and Pi were found at adult age with upregulation of key genes of lipid biosynthesis/metabolism pathways (FASN, ACSS2, ACACA) in obese DL pigs on the one hand and upregulation of genes of cell growth and/or maintenance, protein syntheses as well as cell proliferation pathways (PPARD, POU1F1, IGF2R) in lean Pi pigs on the other hand. Time course analysis of expression profiles of breed differences from foetal to adult stage and functional cluster analysis of the biological processes confirmed the trend of differences between genetically different obese and lean breeds. The highlighted classes of genes showed common breed-typical expression throughout prenatal development and at adult age. The transcriptional differences between obese and lean pigs involving lipid pathways and cell activity are already initiated during early prenatal development. The information about genetic differences between obese and lean pigs reveals a number of functional candidate genes for traits related to obesity and leaness. Keywords: pig, oligo-microarray, prenatal liver expression, adult liver expression, obesity, leaness Porcine liver from three prenatal stages (35, 63, and 91 day post conceptionem, dpc) plus adult age (180 days) of 10 animals of each of the breeds DL and Pi, which differ in body composition, were collected. The hepatic gene expression patterns of DL and Pi breeds were compared at each of the four stages of development. Three or four biological replicate microarray hybridisations were performed for each stage with DL pools labelled with Cy5 and Pi pools labelled with Cy3.

为深入解析肝脏代谢通路以及筛选影响机体组成相关性状的关键转录本，本研究旨在对比两个品种猪的样本："肥胖型"德国长白猪（German Landrace, DL）与"瘦型"皮特兰猪（Pietrain, Pi），采样涵盖产前阶段（受孕后35、63和91天，days post conceptionem, 简称dpc）以及成年阶段（180日龄。
在基因调控数量层面，DL与Pi两品种间最显著的表达差异出现在成年阶段：一方面肥胖型DL猪的脂质生物合成/代谢通路关键基因（FASN、ACSS2、ACACA）显著上调；另一方面瘦型Pi猪则显著上调细胞生长/维持、蛋白质合成以及细胞增殖通路相关基因（PPARD、POU1F1、IGF2R）。
对从胎儿到成年阶段的品种表达差异开展时间进程分析，结合生物学过程功能聚类分析，均验证了遗传背景不同的肥胖型与瘦型品种间的表达差异趋势。本研究重点关注的基因类别，在整个产前发育阶段及成年阶段均呈现品种特异性表达模式。肥胖型与瘦型猪之间涉及脂质通路与细胞活性相关的转录差异，早在产前早期发育阶段就已启动。
本研究获取的肥胖型与瘦型猪的遗传差异信息，可为肥胖与瘦体型状相关的诸多功能性候选基因提供参考依据。
关键词：猪、寡核苷酸微阵列（oligo-microarray）、产前肝脏基因表达、成年肝脏基因表达、肥胖、瘦型

本研究收集了DL与Pi两个品种各10头猪的肝脏组织样本，采样覆盖3个产前阶段（受孕后35、63和91天，dpc）以及180日龄成年阶段，两品种在机体组成上存在显著差异。本研究在四个发育阶段中，分别对比了DL与Pi两品种的肝脏基因表达谱。每个阶段均以Cy5标记DL组样本池、Cy3标记Pi组样本池，完成3~4次生物学重复的微阵列杂交实验。