School of Medicine, University of St Andrews, St Andrews, Fife, KY16 9TF, UK.
FASEB J. 2010 Oct;24(10):3981-91. doi: 10.1096/fj.10-161000. Epub 2010 Jun 14.
This study investigated the expression and tissue distribution of inositol monophosphatase (IMPA1) and characterized its role in salinity adaptation in the eel. The coding sequence of eel IMPA1 was determined and confirmed to be orthologous to the mammalian gene/enzyme by phylogenetic analysis and structural modeling. Quantitative real-time PCR and Western blot techniques indicated up to 17-fold increases in mRNA expression and 2-fold increases in protein abundance in major osmoregulatory tissues following transfer of fish to seawater (SW). This was accompanied by up to 5-fold increases in enzyme activity, and 1.8- and 3-fold increases in inositol contents within the gill and kidney, respectively. Immunohistological studies revealed that IMPA1 protein expression predominated in SW-acclimated fish within basal epithelial/epidermal layers of the gill, esophagus, intestine, skin, and fins. SW transfer also induced a 10-fold increase in inositol content in the fin. IMPA1 immunoreactivity was also identified in chondrocytes within the cartilagenous matrix of the gills and fins, as well as in clusters of interstitial cells surrounding the kidney tubules. The observed increases in expression of IMPA1 highlight a protective role for inositol within various eel tissues following SW acclimation. This constitutes an adaptive mechanism in teleost fish naturally exposed to hypertonic environments.
本研究调查了肌醇单磷酸酶 (IMPA1) 的表达和组织分布，并探讨了其在鳗鲡盐度适应中的作用。通过系统进化分析和结构建模，确定并证实了鳗鲡 IMPA1 的编码序列与哺乳动物基因/酶具有同源性。定量实时 PCR 和 Western blot 技术表明，鱼类转移到海水 (SW) 后，主要渗透压调节组织中的 mRNA 表达增加了 17 倍，蛋白质丰度增加了 2 倍。伴随着酶活性增加了 5 倍，鳃和肾脏中的肌醇含量分别增加了 1.8 倍和 3 倍。免疫组织化学研究表明，在适应 SW 的鱼类中，IMPA1 蛋白表达主要位于鳃、食管、肠、皮肤和鳍的基底层上皮/表皮中。SW 转移还导致鳍中的肌醇含量增加了 10 倍。在鳃和鳍的软骨基质以及围绕肾小管的间质细胞簇中也鉴定到了 IMPA1 免疫反应性。IMPA1 表达的增加表明，在 SW 适应后，肌醇在各种鳗鲡组织中发挥了保护作用。这构成了对自然暴露于高渗环境的硬骨鱼类的一种适应性机制。
