Messina A, Nannelli A, Fiorio R, Longo V, Gervasi P G
Istituto di Fisiologia Clinica CNR, Area della Ricerca CNR, Pisa, Italy.
Toxicology. 2009 Jun 16;260(1-3):47-52. doi: 10.1016/j.tox.2009.03.003. Epub 2009 Mar 20.
The presence and inducibility of specific CYPs (1A1, 1A2, 1B1, 2B22, 3A22, 3A29 and 3A46) and the related transcriptional factors (AhR, CAR, PXR, and HNF4alpha) were investigated, at activity and/or transcriptional level, in liver, respiratory and olfactory mucosa of control and beta-naphthoflavone (betaNF)-treated pigs an agonist of AhR, or rifampicin (RIF), an agonist of PXR. Experiments with real-time PCR showed that CYP1A1 mRNA was enhanced by betaNF, although at different extent, in liver, respiratory and olfactory tissues, whereas mRNAs of CYP1A2 and 1B1 were increased only in liver. Accordingly, in microsomes of both nasal tissues, the transcriptional activation of CYP1A1 was accompanied by an induction of ethoxyresorufin deethylase activity (a marker of this isoform) but not of methoxyresorufin demethylase activity (a marker of CYP1A2). The rifampicin treatment resulted in a transcriptional activation of CYP2B22 and CYP3As genes in liver but not in respiratory and olfactory mucosa. In parallel, the marker activity of CYP2B (ethoxy 4-(trifluoromethyl)coumarin deethylase) and CYP3As (6beta-testosterone hydroxylase and benzyloxyquinoline debenzylase) were induced in liver microsomes but not in the nasal ones. Considering the transcriptional factors, the basal expression of AhR mRNA was found to be as high in liver as in both nasal tissues but not susceptible to induction by betaNF. Also PXR mRNA was found, aside liver, well expressed in the nasal tissues, whereas CAR and HNF4alpha mRNAs were barely detected. In any case, these transcripts appeared to be enhanced by RIF treatment. Our results demonstrated that in the respiratory and olfactory mucosa of pig, although the presence of AhR, only CYP1A1, but not 1A2 and 1B1 resulted to be inducible by betaNF. Similarly, it was observed that in these nasal tissues, although the presence of PXR, neither CYP2B22 nor any CYP3A resulted to be inducible by RIF. Thus, the regulation mechanism of CYP1A2, 1B1, 2B22, 3A22, 3A29, and 3A46, in the nasal mucosa involves tissue-enriched transcriptional factors others than AhR, CAR, PXR, and HNF4alpha, which are fundamental in liver.
在对照猪以及用β-萘黄酮（βNF，一种芳烃受体（AhR）激动剂）或利福平（RIF，一种孕烷X受体（PXR）激动剂）处理的猪的肝脏、呼吸道和嗅觉黏膜中，研究了特定细胞色素P450（CYP）（1A1、1A2、1B1、2B22、3A22、3A29和3A46）及其相关转录因子（AhR、组成型雄烷受体（CAR）、PXR和肝细胞核因子4α（HNF4α））在活性和/或转录水平上的存在情况及诱导性。实时聚合酶链反应（PCR）实验表明，βNF可使肝脏、呼吸道和嗅觉组织中的CYP1A1信使核糖核酸（mRNA）增强，尽管增强程度不同，而CYP1A2和1B1的mRNA仅在肝脏中增加。相应地，在两个鼻组织的微粒体中，CYP1A1的转录激活伴随着乙氧基亚芴基脱乙基酶活性（该同工酶的标志物）的诱导，但不伴随着甲氧基异芴基脱甲基酶活性（CYP1A2的标志物）的诱导。利福平处理导致肝脏中CYP2B22和CYP3A基因的转录激活，但在呼吸道和嗅觉黏膜中未出现。同时，肝脏微粒体中CYP2B（乙氧基4-（三氟甲基）香豆素脱乙基酶）和CYP3A（6β-睾酮羟化酶和苄氧基喹啉脱苄基酶）的标志物活性被诱导，但鼻组织微粒体中未被诱导。考虑到转录因子，发现AhR mRNA的基础表达在肝脏和两个鼻组织中一样高，但不易被βNF诱导。还发现，除肝脏外，PXR mRNA在鼻组织中也有良好表达，而CAR和HNF4α mRNA几乎未被检测到。无论如何，这些转录本似乎可被RIF处理增强。我们的结果表明，在猪呼吸道和嗅觉黏膜中，尽管存在AhR，但只有CYP1A1可被βNF诱导，而CYP1A2和1B1则不能。同样，观察到在这些鼻组织中，尽管存在PXR，但CYP2B22和任何CYP3A均不能被RIF诱导。因此，鼻黏膜中CYP1A2、1B1、2B22、3A22、3A29和3A46的调控机制涉及除AhR、CAR、PXR和HNF4α之外的组织富集转录因子，而这些转录因子在肝脏中是至关重要的。
