Hao Zhiming, Li Xiaohua, Qiao Taidong, Fan Daiming
Department of Gastroenterology, 1st Affiliated Hospital, School of Medicine, Xi'an Jiaotong University, Xi'an 710061, China.
Int J Biol Macromol. 2008 Jan 1;42(1):27-32. doi: 10.1016/j.ijbiomac.2007.08.009. Epub 2007 Sep 8.
CIAPIN1 is a newly identified anti-apoptosis molecule which plays an important role in definitive haematopoiesis in mouse fetal liver and confers multidrug resistance in gastric cancer cells. However, the biophysical function of CIAPIN1 is far from elucidated. Bioinformatics predicts that CIAPIN1 may contain a generic methyltransferase motif and a Zn-ribbon-like motif. Based on these data, we postulated that CIAPIN1 might be a DNA or RNA methyltransferase. To substantiate this proposal, recombinant human CIAPIN1 (rhCIAPIN1) was expressed by a baculovirus-insect cell system and purified by Ni-NTA affinity chromatography. In vitro DNA and RNA methyltransferring tests, DNA demethylation test and S-adenosyl-l-[methyl-3H]methionine (3H-AdoMet) binding test were carried out. Our experiments failed to demonstrate that rhCIAPIN1 had any DNA, RNA methyltransferase activity, DNA demethylase activity, or had the capability of binding AdoMet in vitro. Further studies are needed to definitely clarify whether CIAPIN1 has methyltransferase activity.
CIAPIN1是一种新发现的抗凋亡分子，在小鼠胎肝的确定性造血过程中发挥重要作用，并赋予胃癌细胞多药耐药性。然而，CIAPIN1的生物物理功能远未阐明。生物信息学预测CIAPIN1可能包含一个通用甲基转移酶基序和一个锌带样基序。基于这些数据，我们推测CIAPIN1可能是一种DNA或RNA甲基转移酶。为证实这一推测，重组人CIAPIN1（rhCIAPIN1）通过杆状病毒-昆虫细胞系统表达，并通过镍-亚氨基二乙酸亲和层析进行纯化。进行了体外DNA和RNA甲基转移试验、DNA去甲基化试验以及S-腺苷-L-[甲基-³H]甲硫氨酸（³H-AdoMet）结合试验。我们的实验未能证明rhCIAPIN1在体外具有任何DNA、RNA甲基转移酶活性、DNA去甲基酶活性或结合AdoMet的能力。需要进一步研究以明确CIAPIN1是否具有甲基转移酶活性。
