食管癌相关基因1编码蛋白的相互作用蛋白筛选

Search for interacting proteins of esophageal cancer related gene-1 encoded protein through the yeast two-hybrid system

目的 筛选与食管癌相关基因 1(ECRG 1)编码蛋白相互作用的蛋白 ,为其功能研究奠定基础。方法 将编码ECRG 1羧基端 378个氨基酸的DNA序列插入到pGBKT7 DNA BD载体 ,与编码Gal4DNA结合结构域的DNA序列拼接做融合基因 ,将此重组质粒与已克隆到pACT2载体上的人肝脏cDNA文库 (与编码Gal4激活结构域的DNA序列融合 )共转化酵母细胞AH10 9。ECRG 1与相应的人肝脏cDNA片段编码的蛋白发生相互作用后 ,可激活报告基因的表达。排除假阳性后 ,阳性克隆中的文库cDNA进行测序分析。同源性检索搜寻GenBank中与之相同或相似的序列。结果 共转化得到约 3× 10 6个转化子 ,2 3个克隆有报告基因的表达。排除假阳性后 ,得到 2个阳性克隆 ,它们分别编码Miz 1(myc interactingznfingerprotein 1)和FLNA(actin bindingprotein 2 80 )。结论 ECRG 1基因编码蛋白在酵母中可特异性的结合Miz 1和FLNA ,提示ECRG 1可能通过与MIZ 1、FLNA相互作用参与调控细胞周期的运行。

Objective To understand the role that esophageal cnacer related gene-1 (ECRG-1) plays and to search for ECRG-1-interacting proteins. Methods A DNA fragment encoding the carboxy-terminus of ECRG-1(amino acids 40-418) was inserted into pGBKT7-DNA-BD vector and fused in-frame to the DNA-binding domain of GAL4. Then, it was used as a bait to screen the human fetal liver cDNA library by yeast two-hybrid, with the cDNA fragment inserted into pACT2 vector and fused in-frame to the Gal4 activation domain. If ECRG-1 interacted with a protein encoded by a cDNA fragmant in the yeast, the transcription of reporter Gene could be activated. With the false positive clonies eliminated, the inserts in the positive plasmids were sequenced and compared to those in the GenBank. Results In approximately 3×10 6 independent tansformants screened, 23 clonies exhibited the expression of reporter gene. After eliminating the false positive clonies, two cDNA fragments were obtained. DNA sequencing revealed that one encoded Miz-1(Myc-interacting Zn finger protein-1), and another encoded FLNA(actin-binding protein-280), Miz-1, being a Zn finger protein, could be bound to p15 promotor and activated the transcription. FLNA, being an actin-binding protein took part in the TGF-β pathway via interaction with Smad. Conclusion ECRG-1 is able to be specifically bound to Miz-1 and FLNA in the yeast. It may play a role in the regulation of cell cycle via interaction with Miz-1 and FLNA.