The family of hepatoma-derived growth factor proteins: characterization of a new member HRP-4 and classification of its subfamilies
The family of hepatoma-derived growth factor proteins: characterization of a new member HRP-4 and classification of its subfamilies
复制标题
DOI：
10.1042/bj20011811
复制
发表时间：
2002-09-01
影响因子：
4.1
通讯作者：
Gieselmann, V
中科院分区：
文献类型：
--
作者：
Dietz, F;Franken, S;Gieselmann, V
肝癌衍生生长因子（HDGF）相关蛋白（HRPs）包括一个以HDGF命名的多肽家族，其通过其对成纤维细胞的促有丝分裂活性来鉴定。在本研究中，我们描述了一个迄今未知的HRP，称为HRP-4。牛HRP-4（bHRP-4）的cDNA预测了235个氨基酸的多肽。各种牛组织的北方和西方印迹分析表明，HRP-4只在睾丸中表达。在无血清培养基中，以1 ng/ml的最佳浓度，人工产生的bHRP-4和鼠HDGF（mHDGF）组氨酸标记的多肽对培养的原代人成纤维细胞显示出生长因子活性。生长因子活性随浓度增加而下降，在1 μ g/ml时达到背景水平。融合蛋白bHRP-4-绿色荧光蛋白和mHGF-绿色荧光蛋白在HEK-293细胞中的表达证实了蛋白质的核定位。bHRP-4和mHDGF与糖胺聚糖肝素和硫酸乙酰肝素结合，但不与硫酸软骨素结合。确定这些相互作用的亲和力常数在6和42 nM之间。bHRP-4氨基酸序列与HRP-1-3和p52/75/透镜上皮衍生生长因子（LEDGF）的比较显示，这些蛋白质共享91个氨基酸的保守N-末端部分，但具有不同长度和电荷的C-末端。这证明了这些蛋白质的模块化结构，并允许其根据电荷，大小和序列比较分为三组。HRP-4、HRP-1和HDGF是小的酸性蛋白，HRP-3是小的碱性蛋白，而HRP-2和p52/75/LEDGF是较大的碱性蛋白。
Hepatoma-derived growth factor (HDGF)-related proteins (HRPs) comprise a family of polypeptides named after HDGF, which was identified by its mitogenic activity towards fibroblasts. In the present study, we describe a hitherto unknown HRP, termed HRP-4. The cDNA of bovine HRP-4 (bHRP-4) predicts a polypeptide of 235 amino acids. Northern- and Western-blot analyses of various bovine tissues demonstrated that HRP-4 is only expressed in the testis. Recombinantly produced bHRP-4 and murine HDGF (mHDGF) histidine-tagged polypeptides display growth-factor activity for cultured primary human fibroblasts at an optimum concentration of 1 ng/ml in serum-free medium. The growth-factor activity declines with increasing concentrations to reach background levels at 1 mug/ml. The expression of the fusion proteins, bHRP-4-green fluorescent protein and mHDGF-green fluorescent protein, in HEK-293 cells demonstrates nuclear localization of the proteins. bHRP-4 and mHDGF bind to the glycosaminoglycans heparin and heparan sulphate, but not to chondroitin sulphate. Affinity constants determined for these interactions are between 6 and 42 nM. Comparison of the bHRP-4 amino acid sequence with HRP-1-3 and p52/75/lens epithelium-derived growth factor (LEDGF) shows that these proteins share a conserved N-terminal part of 91 amino acids but have C-termini of different lengths and charge. This demonstrates the modular structure of these proteins and allows its classification into three groups based on charge, size and sequence comparison. HRP-4, HRP-1 and HDGF are small acidic proteins, HRP-3 is a small basic protein, and HRP-2 and p52/75/LEDGF are larger basic proteins.