Cell Biology and Histology, Dept. of Zoology and Animal Cell Biology, School of Science and Technology, University of the Basque Country, PO Box 644, E-48080, Bilbao, Basque Country, Spain.
Comp Biochem Physiol C Toxicol Pharmacol. 2010 Apr;151(3):334-42. doi: 10.1016/j.cbpc.2009.12.007. Epub 2010 Jan 5.
Benzo(a)pyrene (B(a)P) is a mutagenic polycyclic aromatic hydrocarbon (PAH) commonly released into the environment. B(a)P induces phase I biotransformation metabolism and peroxisome proliferation which is characterised in rodents by increased peroxisomal volume density, accompanied by the transcriptional induction of peroxisomal proteins. The aim of the present work was to study peroxisome proliferation at the transcriptional level, in comparison to the transcription of the well-characterised cytochrome P450 1A gene (cyp1a) in the thicklip grey mullet Chelon labrosus. For this purpose, genes coding for the major peroxisomal membrane protein PMP70 and CYP1A were cloned using degenerate primers. Then juvenile mullets were single injected with B(a)P (5mg/kg) and transcription of palmitoyl-CoA oxidase (aox1), multifunctional protein (mfp1), 3-ketoacyl-CoA thiolase (thio), Delta(2),Delta(4)dienoyl-CoA reductase 2, pmp70, catalase and cyp1a was semi-quantified in liver and gills 1 and 7days after the injection. Transcription of aox1 and cyp1a was induced in gills 1day after B(a)P injection. Cyp1a transcription was also induced in mullet liver one day after injection, indicating that B(a)P was available for the liver. This was further proved by the significant accumulation of B(a)P-like metabolites in bile 7days after the injection. In liver, aox1, mfp1 and thio transcription was induced at day 1 followed by the induction of catalase transcription at day 7 that may reflect a response to an oxidative stress caused by B(a)P itself or by oxyradicals produced through the biotransformation metabolism and the peroxisomal beta-oxidation. These hepatic responses were not reflected at AOX1 activity level. In conclusion, it has been shown for the first time that the three enzymes in the fish peroxisomal beta-oxidation pathway are transcriptionally induced by B(a)P. It remains to be tested whether this enhanced transcription is reflected in an increase in the volume of peroxisomes.
苯并(a)芘（B(a)P）是一种致突变性多环芳烃（PAH），通常会释放到环境中。B(a)P 可诱导 I 相生物转化代谢和过氧化物酶体增殖，在啮齿动物中表现为过氧化物酶体体积密度增加，并伴有过氧化物酶体蛋白的转录诱导。本研究旨在比较厚唇灰鲻 Chelon labrosus 中典型的细胞色素 P450 1A 基因（cyp1a）的转录，在转录水平上研究过氧化物酶体增殖。为此，使用简并引物克隆了编码主要过氧化物酶体膜蛋白 PMP70 和 CYP1A 的基因。然后，将幼鱼单次注射 B(a)P（5mg/kg），并在注射后 1 天和 7 天测量肝脏和鳃中过氧化物酶体氧化酶（aox1）、多功能蛋白（mfp1）、3-酮酰基辅酶 A 硫解酶（thio）、Δ(2),Δ(4)二烯酰基辅酶 A 还原酶 2、pmp70、过氧化氢酶和 cyp1a 的转录水平。注射后 1 天，aox1 和 cyp1a 在鳃中被诱导转录。注射后 1 天，cyp1a 在鱼肝脏中也被诱导转录，表明 B(a)P 可被肝脏利用。这进一步通过注射后 7 天胆汁中 B(a)P 样代谢物的显著积累得到证实。在肝脏中，aox1、mfp1 和 thio 的转录在第 1 天被诱导，随后在第 7 天被诱导的过氧化氢酶转录可能反映了 B(a)P 本身或通过生物转化代谢和过氧化物体β-氧化产生的氧自由基引起的氧化应激的反应。这些肝反应在 AOX1 活性水平上没有反映出来。总之，这是首次表明鱼类过氧化物酶体β-氧化途径中的三种酶均被 B(a)P 诱导转录。仍有待测试这种增强的转录是否反映在过氧化物酶体体积的增加上。
