정상사람의 공장에서 유도성 NOS 유전자의 지속적 발현과 역할에 관한 연구

초록

It has been previously demonstrated that inducible nitric oxide synthase (jNOS) is constitutively expressed in some normal human tissues. Here we demonstrate the expression of a specific iNOS in the normal jejunum of human digestive tract. RT-PCR and Northern-blot analyses revealed constitutive expression of iNOS mRNA. In the transcriptional level, the size of mRNA expressed was longer (4.5 kb) than that normally observed in other tissues and cells like macophages and hepatocytes (4.2 kb). The expression of this large size iNOS mRNA in the jejunum was a special characteristic of iNOS in digestive tract tissues such as small or large intestines. This length difference is presumed to be due to alternative splicing mechanism. In the translational level, the expression of 130 kDa iNOS protein was identified by Western-blotting with monoclonal antibodies raised against the pure enzyme. The iNOS activity in enzyme identities such as Ca++-and BH4-dependency. The enzyme extracted from jejunum showed strong Ca++-independency but BH4-dependency. These results suggest that the NO gases produced both by the iNOS constitutively expressed in jejunum and also by the iNOS inducible with certain endotoxins or cytokines in intestines may play an important role both in maintaining normal intestinal homeostsis and also in protection system.