Gropp F N C, Greger D L, Morel C, Sauter S, Blum J W
Veterinary Physiology, Vetsuisse Faculty, University of Bern, CH-3012 Bern, Switzerland.
J Anim Sci. 2006 Oct;84(10):2684-91. doi: 10.2527/jas.2006-174.
Nuclear receptors (NR) are ligand-activated transcription factors that regulate different metabolic pathways by influencing the expression of target genes. The current study examined mRNA abundance of NR and NR target genes at different sites of the gastrointestinal tract (GIT) and the liver of healthy dogs (Beagles; n = 11). Samples of GIT and liver were collected postmortem and homogenized, total RNA was extracted and reverse transcribed, and gene expression was quantified by real-time reverse-transcription PCR relative to the mean of 3 housekeeping genes (beta-actin, glyceraldehyde-3-phosphate dehydrogenase, and ubi-quitin). Differences were observed (P < or = 0.05) in the mRNA abundance among stomach (St), duodenum (Du), jejunum (Je), ileum (Il), and colon (Col) for NR [pregnane X receptor (Du, Je > Il, Col > St), peroxisome proliferator-associated receptor gamma (St, Du, Col > Je, Il), constitutive androstane receptor (Je, Du > Il, Col), and retinoid x receptor alpha (Du > Il)] and NR target genes [glutathione-S-transferase A3-3 (Du > Je > St, Il; St > Col), phenol-sulfating phenol sulfotransferase 1A1 (Du, Je > Il, St; Col > St), cytochrome P450 3A12 (Du, Je > St, Il, Col), multiple drug resistance gene 1 (Du, Je, Il, Col > St), multiple drug resistance-associated protein 2 (Je, Du > Il > St, Col), multiple drug resistance-associated protein 3 (Col > St > Il; Du > Je, Il; St > Il), NR corepressor 2 (St > Il, Col), and cytochrome P450 reductase (St, Du, Je > Il, Col)], but not for peroxisome proliferator-associated receptor alpha. Differences (P > 0.05) in mRNA abundance in the liver relative to the GIT were also observed. In conclusion, the presence of numerous differences in expression of NR and NR target genes in different parts of the GIT and in liver of healthy dogs may be associated with location-specific functions and regulation of GIT regions.
核受体（NR）是配体激活的转录因子，通过影响靶基因的表达来调节不同的代谢途径。本研究检测了健康犬（比格犬；n = 11）胃肠道（GIT）不同部位和肝脏中NR及其靶基因的mRNA丰度。在犬死后采集GIT和肝脏样本并进行匀浆，提取总RNA并进行逆转录，通过实时逆转录PCR相对于3个管家基因（β-肌动蛋白、甘油醛-3-磷酸脱氢酶和泛素）的平均值对基因表达进行定量分析。观察到NR [孕烷X受体（十二指肠、空肠>回肠、结肠>胃）、过氧化物酶体增殖物激活受体γ（胃、十二指肠、结肠>空肠、回肠）、组成型雄甾烷受体（空肠、十二指肠>回肠、结肠）和视黄酸X受体α（十二指肠>回肠）]及其靶基因[谷胱甘肽-S-转移酶A3-3（十二指肠>空肠>胃、回肠；胃>结肠）、苯酚硫酸化苯酚磺基转移酶1A1（十二指肠、空肠>回肠、胃；结肠>胃）、细胞色素P450 3A12（十二指肠、空肠>胃、回肠、结肠）、多药耐药基因1（十二指肠、空肠、回肠、结肠>胃）、多药耐药相关蛋白2（空肠、十二指肠>回肠>胃、结肠）多药耐药相关蛋白3（结肠>胃>回肠；十二指肠>空肠、回肠；胃>回肠）、NR共抑制因子2（胃>回肠、结肠）和细胞色素P450还原酶（胃、十二指肠、空肠>回肠、结肠）]在胃（St）、十二指肠（Du）、空肠（Je）、回肠（Il）和结肠（Col）之间的mRNA丰度存在差异（P≤0.05），而过氧化物酶体增殖物激活受体α则无差异。同时也观察到肝脏中mRNA丰度相对于GIT存在差异（P>0.05）。总之，健康犬GIT不同部位和肝脏中NR及其靶基因表达存在众多差异，这可能与GIT区域的位置特异性功能和调节有关。
