增强子结合蛋白家族的新基因HP8的部分cDNA克隆

探讨人的增强子结合蛋白（Ｃ／ＥＢＰ）相关基因。方法以大鼠Ｃ／ＥＢＰｃＤＮＡ为探针，筛选人胎盘ｃＤＮＡ文库。结果得到一个含有１９７５碱基命名为ＨＰ８的ｃＤＮＡ克隆，其中１～６０４位碱基属编码区。经基因数据库查对未发现同源基因。该基因编码的蛋白Ｃ－末端含有亮氨酸拉链结构（ｌｅｕｃｉｎｅ ｚｉｐｐｅｒ ｓｔｒｕｃｅｕｒｅ）和Ｃ／ＥＢＰ功能区（Ｃ－末端６０个氨基酸）同源性高达９７％，而上游编码区则与Ｃ／ＥＢＰ及其已知家族同源性很低，表明该基因属Ｃ／ＥＢＰ基因家族新成员。基因组Ｓｏｕｔｈｅｒｎ杂交证实该基因为单拷贝基因。在１４种胎儿组织中显示小肠、皮肤高表达，肾上腺中度表达，肝、肺、肾、甲状腺、胆囊低表达。在３例正常成人肝组织中仅１例低表达，而在５对肝癌及癌旁肝组织中显示２例癌组织及１例癌旁组织高表达。结论以上结果提示该基因可能与细胞增殖有关。

HP8 : The partial cDNA clone of a novel member of C/EBP gene family

Objective To explore the human C/EBP related genes. Methods Screening human placenta cDNA library with rat C/EBP cDNA probe. Results One positive clone , HP8 was obtained. This clone contained 1975 base pair. which include 604 coding base pairs. The matched DNA sequence was not found in the gene database (EMBL 95. 6 ) . The 201 amino acids encoded by this gene had the leucine zipper structure and demonstrated the highest homology ( 97%) with C/EBP throughout the DNA-binding domain and leucine repeat region (C-terminal 60 amino acids ) . Beyond this region , only low homology was detected in HP8 protein and C/EBP or C/EBP related proteins. Herewith , HP8 was defined as a novel member of C/EBP gene family. Genomic Southern blot analysis confirmed that HP8 was a single copy gene . Northern blot analysis in 14 different fetus tissues showed that high level of HP8 mRNA was expressed in small intestine and skin , middle level in adrenal gland , low level in liver , lung , kidney , thyroid gland and gallbladder. In 3 human adult liver tissues , only one low level HP8 mRNA , whereas of 5 hepatomas and one of their surrounding nontumorous hepatic tissues had , high level HP8 mRNA. Concl usion These results. suggested that HP8 gene might be a transactivator related to cell growth . As Northern blot analysis indicated , HP8 gene has about 2 . 7Kb full length cDNA .