Regional localization of cytochrome P4501A1 mRNA expression in extra-hepatic tissues using in-situ reverse transcription PCR amplification

Cytochrome P4501A1 (CYP1A1)의 유전자 분포에 대한 광범위한 연구에도 불구하고, 현재까지 간장외 조직에서의 유전자 발현양상에 대한 연구는 미미한 실정이다. 본 연구에서는 면역조직화학적 방법, reverse transcription polymerase chain reaction (RT-PCR), Southern analysis, in situ RT-PCR 방법으로 간, 이자, 신장, 폐 및 뇌에서 CYP1A1유전자 발현양상을 관찰하였다. CYP1A1 mRNA 및 단백질은 2,3,7,8-tetrachlorodibenzo-p-dioxin 혹은 YH439 투여에 의해 유도되었는데, 간장에서는 주로 간문맥주변에 나타났으며, 신장에서는 세뇨관 상피세포에서, 폐에서는 기관지 상피세포에서, 그리고 이자에서는 α-cells에서 동정이 되었으나, in-situ RT-PCR 및 면역조직염색상에서는 관찰되지 않았다. 이와 같이 CYP1A1 mRNA 및 단백질이 세포 특이적으로 발현된다는 사실은 환경오염물질과 같은 유해물질에 노출되었을 경우 방어기전에 중요한 기능을 할 것으로 사료된다.

Despite extensive research on the induction mechanism of the cytochrome P4501Al (CYPlAl) gene, its regional expression in extra-hepatic tissues is not well characterized. Here we determined the localization of CYPIAl expression using immunohistochemistry, reverse transcription and polymerase chain reaction (RT-PCR), Southern analysis and in-situ RT-PCR. The levels of CYP1Al mRNA and protein, undetectable in untreated rat tissues, were significantly elevated by treatment with either 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) or a synthetic thiazolium compound, YH439. Elevated levels of CYP1A1 mRNA transcript and immunoreactive CYP1A1 protein were mainly observed in the periportal region of the liver, the cortical tubular epithelium of the kidney, bronchiolar epithelial cells of the lung and peripheral cells of the pancreatic islets, most likely a-cells. In contrast, neither CYP1A1 mRNA nor its protein was detected in brain by in situ RT-PCR and immunohistochemistry even after treatment with YH439 or TCDD, although an increased level of CYP1A1 mRNA transcript in brain was recognized by RT-PCR followed by Southern analysis. The selective regional distribution of CYP1A1 mRNA and protein may play a role in the preferential toxicity of certain extra-hepatic cells exposed to potentially toxic agents including environmental carcinogens.