FIF [fibroblast growth factor-2 (FGF-2)-interacting-factor], a nuclear putatively antiapoptotic factor, interacts specifically with FGF-2
FIF [fibroblast growth factor-2 (FGF-2)-interacting-factor], a nuclear putatively antiapoptotic factor, interacts specifically with FGF-2
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DOI：
10.1210/me.14.11.1709
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发表时间：
2000-11-01
影响因子：
--
通讯作者：
Bugler, B
中科院分区：
文献类型：
--
作者：
Van den Berghe, L;Laurell, H;Bugler, B
大量证据表明，成纤维细胞生长因子2（FGF-2）的某些活性依赖于内分泌作用模式。最近，我们发现FGF-2的三种高分子量（HMM）核形式是320 kDa蛋白复合物的一部分，而胞质AUC起始形式包含在130 kDa复合物中。因此，FGF内源性靶标的表征对于阐明其内源性活性变得至关重要。通过筛选基于GAL 4的酵母双杂交表达文库，我们已经分离出编码55 kDa的核蛋白的基因，FIF（FGF 2-interacting-factor），其与FGF 2特异性相互作用，但不与FGF-1、FGF-3或FGF-6相互作用。在该系统中，FIF与NH 2延伸的24-kDa FGF形式的相互作用与18-kDa形式的相互作用同样良好，表明FIF结合基序位于FGF-2的最后155个氨基酸中。然而，免疫共沉淀实验显示与HMM FGF-2的排他性关联。预测的蛋白质包含一个典型的亮氨酸拉链结构域和三个重叠的疏水七肽重复序列。跨越这些重复的区域与位于FIF蛋白的N-末端部分的区域一起参与与FGF-2的结合。与全长FIF蛋白相反，几种缺失构建体能够反式激活lac-Z报告基因。此外，COOH-末端部分，而不是全长FIF蛋白，先前已被证明具有抗凋亡特性。因此，我们讨论的可能性，这些活动可以反映FIF的生理功能，通过其与FGF-2的相互作用。
Numerous evidence indicates that some of the activities of fibroblast growth factor 2 (FGF-2) depend on an intracrine mode of action. Recently, we showed that three high molecular mass (HMM) nuclear forms of FGF-2 are part of a 320-kDa protein complex while the cytoplasmic AUG-initiated form is included in a 130-kDa complex. Consequently, the characterization of FGF endogenous targets has become crucial to allow the elucidation of their endogenous activities. Through the screening of GAL4-based yeast two-hybrid expression libraries, we have isolated a gene encoding a nuclear protein of 55 kDa, FIF (FGF2-interacting-factor), which interacts specifically with FGF2 but not with FGF-1, FGF-3, or FGF-6. In this system, FIF interacts equally well with the NH2-extended 24-kDa FGF form as with the 18-kDa form, indicating that the FIF-binding motif is located in the last 155 amino acids of FGF-2. Nevertheless, coimmunoprecipitation experiments showed an exclusive association with HMM FGF-2. The predicted protein contains a canonical leucine zipper domain and three overlapping hydrophobic heptad repeats. The region spanning these repeats is, together with a region located in the N-terminal part of the FIF protein, implicated in the binding to FGF-2. In contrast to the full-length FIF protein, several deletion constructs were able to transactivate a lac-Z reporter gene. Furthermore, the COOH-terminal part, but not the full-length FIF protein, has previously been shown to exhibit antiapoptotic properties. Thus we discuss the possibility that these activities could reflect a physiological function of FIF through its interaction with FGF-2.