Insulin-like growth factor-binding protein 5 (IGFBP-5) interacts with a four and a half LIM protein 2 (FHL2)
Insulin-like growth factor-binding protein 5 (IGFBP-5) interacts with a four and a half LIM protein 2 (FHL2)
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DOI：
10.1074/jbc.m110872200
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发表时间：
2002-04-05
影响因子：
4.8
通讯作者：
Mohan, S
中科院分区：
文献类型：
--
作者：
Amaar, YG;Thompson, GR;Mohan, S
最近使用胰岛素样生长因子I（IGF-1）敲除小鼠的研究表明，IGF结合蛋白（IGFBP）-5是一种重要的骨形成调节剂，其本身是一种生长因子，具有不依赖于IGF的细胞作用。由于 IGFBP-5 含有介导 IGFBP-5 转运至细胞核的核定位序列，因此我们提出 IGFBP-5 与核蛋白相互作用，影响骨形成相关基因的转录。因此，我们进行了研究，以 IGFBP-5 作为诱饵，在 U2 人骨肉瘤 cDNA 文库的酵母双杂交筛选中鉴定与 IGFBP-5 结合的蛋白质。与诱饵强烈相互作用的五个相关克隆对应于 FHL2 基因，该基因包含四个半 LIM 结构域。对过表达 FHL2 和 IGFBP-5 的 U2 细胞裂解物进行的免疫共沉淀研究证实，IGFBP-5 和 FHL2 之间的相互作用发生在整个细胞中。体外相互作用研究表明，纯化的 FHL2 与 IGFBP-5 相互作用，但不与 IGFBP-3、-4 或 -6 相互作用。 Northern blot分析显示FHL2在人成骨细胞中强烈表达。从 Western 免疫印迹分析和免疫荧光来看，FHL2 和 IGFBP-5 的核定位是明显的。 FHL2 作为 IGFBP-5 和其他骨调节剂在成骨细胞中的作用的细胞内介质的作用需要在未来的研究中得到验证。
Recent studies using insulin-like growth factor I (IGF-1) knockout mice demonstrate that IGF-binding protein (IGFBP)-5, an important bone formation regulator, itself is a growth factor with cellular effects not dependent on IGFs. Because IGFBP-5 contains a nuclear localization sequence that mediates transport of IGFBP-5 into the nucleus, we propose that IGFBP-5 interacts with nuclear proteins to affect transcription of genes involved in bone formation. We therefore undertook studies to identify proteins that bind to IGFBP-5 using IGFBP-5 as bait in a yeast two-hybrid screen of a U2 human osteosarcoma cDNA library. Five related clones that interacted strongly with the bait corresponded to the FHL2 gene, which contains four and a half LIM domains. Co-immunoprecipitation studies with lysates from U2 cells overexpressing FHL2 and IGFBP-5 confirmed that interaction between IGFBP-5 and FHL2 occurs in whole cells. In vitro interaction studies revealed that purified FHL2 interacted with IGFBP-5 but not with IGFBP-3, -4, or -6. Northern blot analysis showed that FHL2 was strongly expressed in human osteoblasts. Nuclear localization of both FHL2 and IGFBP-5 was evident from Western immunoblot analysis and immunofluorescence. The role of FHL2 as an intracellular mediator of the effects of IGFBP-5 and other osteoregulatory agents in osteoblasts will need to be verified in future studies.