Expression and cellular localization of melatonin-synthesizing enzymes in the rat lens
Expression and cellular localization of melatonin-synthesizing enzymes in the rat lens
复制标题
DOI：
10.1111/j.1600-079x.2006.00389.x
复制
发表时间：
2007-01-01
影响因子：
10.3
通讯作者：
Shimizu, Kimiya
中科院分区：
文献类型：
--
作者：
Itoh, Masanori T.;Takahashi, Noriyuki;Shimizu, Kimiya
褪黑素（n -乙酰-5-甲氧基色胺）可以防止氧化应激引起的白内障发展，以前的研究表明晶状体可以合成褪黑素。在本研究中，我们检测了褪黑素生物合成的两个关键酶，芳基烷基胺n -乙酰转移酶（AANAT）和羟基吲哚- o -甲基转移酶（HIOMT）是否在成年雄性大鼠的晶状体中表达。逆转录聚合酶链反应分析表明AANAT和HIOMT mrna均在晶状体中表达。AANAT蛋白的Western blotting结果显示，晶状体与松果体一样含有AANAT蛋白，分子量为24 kDa。免疫组化显示AANAT蛋白定位于晶状体皮质纤维细胞。血清素是AANAT的底物和褪黑素前体，在这个区域也被发现。这些发现表明晶状体表达AANAT和HIOMT，并提示皮质纤维细胞是晶状体中主要的褪黑激素合成位点。晶状体皮质纤维细胞中局部合成的褪黑素可能保护晶状体本身免受白内障的发展。
Melatonin (N-acetyl-5-methoxytryptamine) prevents oxidative stress-induced cataract development, and previous studies have suggested that the ocular lens synthesizes melatonin. In the present study, we examined whether two key enzymes in melatonin biosynthesis, arylalkylamine N-acetyltransferase (AANAT) and hydroxyindole-O-methyltransferase (HIOMT), are expressed in the lens of adult male rats. Reverse transcriptase-polymerase chain reaction analyses demonstrated that both AANAT and HIOMT mRNAs are expressed in the lens. Western blotting for AANAT protein showed that the lens, like the pineal gland, contains this enzyme protein with a molecular mass of 24 kDa. Immunohistochemistry revealed that AANAT protein is localized to the lens cortical fiber cells. Serotonin, which is a substrate for AANAT and a melatonin precursor, was also found in this region. These findings demonstrate that the lens expresses AANAT and HIOMT, and suggest that the cortical fiber cells are the main melatonin-synthesizing sites in the lens. Locally synthesized melatonin in the lens cortical fiber cells may protect the lens itself from cataract development.