Creation and characterization of GH binding protein gene disrupted mice

描述（由申请人提供）：迄今为止，生长激素结合蛋白（GHBP）的生物学作用在很大程度上仍然未知。虽然已经提出了许多理论，但没有直接证据可以确定这种蛋白质的特定作用。我们和其他人认为，GHBP很可能在GH/IGF- 1轴中发挥重要作用。对此的主要论点是由于哺乳动物中产生相同蛋白的两种不同机制的趋同进化（即在人类中，GHBP是通过GH受体（GHR）胞外结构域的蛋白水解切割产生的，而在啮齿动物中，GHBP是通过GHR前体mRNA的选择性剪接产生的）。因此，我们认为阐明GHBP功能的最佳方法是建立GHBP基因特异性破坏或“敲除”小鼠系。因此，本研究的目的是创建第一个GHBP特异性基因破坏的小鼠，然后确定GHBP对这些动物的生长表型以及其他代谢过程的贡献。我们的实验室已经破坏了小鼠GHR/BP基因，并产生了联合GHR/GHBP“敲除”小鼠。在纯合状态下，这些小鼠表现出侏儒表型，并作为称为Laron综合征的人GH不敏感状态的模型。尽管这些小鼠矮小肥胖，但它们对胰岛素的作用极其敏感，对糖尿病肾损伤具有抵抗力，令人惊讶的是，它们的寿命延长了。有了这个动物提供的背景，我们现在准备测试的具体假设有关的GHBP在体内的重要性，通过孤立的GHBP基因缺陷，使用有针对性的基因破坏方法。我们有信心，许多关于GHBP的生物学作用的问题将得到回答，除了新的问题被提出，一旦GHBP基因破坏的小鼠产生。该提案旨在阐明生长激素结合蛋白（GHBP）的作用，GHBP是一种蛋白质，其功能除了其结合血液中生长激素（GH）的能力之外，在很大程度上仍未知。与GHBP不同，GH的功能已得到充分证实，并且已知GH在正常代谢和几种疾病（如糖尿病、癌症甚至衰老）的进展中发挥重要作用。因此，从这一建议中获得的结果不仅将进一步加深我们对GH的理解，而且可以帮助我们进一步了解复杂的代谢条件和衰老过程。

DESCRIPTION (provided by applicant): To date, the biological role of growth hormone binding protein (GHBP) remains largely unknown. While many theories have been put forth, there is no direct evidence that can identify a specific role for this protein. We and others believe that it is highly likely that the GHBP plays a significant role in the GH/IGF- 1 axis. The main argument for this is due to the convergent evolution of two distinct mechanisms in mammals to produce the same protein (i.e. in humans the GHBP is produced by proteolytic cleavage of the GH receptor (GHR) extracellular domain while in rodents GHBP is produced by alternative splicing of the GHR precursor mRNA). Thus, we believe that the best way to elucidate the function of the GHBP is to create a GHBP gene specific disrupted or "knockout" mouse line. Hence, the objective of this research is to create the first GHBP specific gene-disrupted mouse and then to determine the contributions of GHBP on the growth phenotype as well as other metabolic processes in these animals. Our laboratory has already disrupted the mouse GHR/BP genes and generated combined GHR/GHBP "knockout" mice. In the homozygous state, these mice display a dwarf phenotype and serve as a model for a human GH- insensitive state termed Laron Syndrome. Although these mice are dwarf and obese, they are extremely sensitive to the action of insulin, resistant to diabetic kidney damage and, surprisingly, they have an extended life span. With this animal providing a background, we are now ready to test the specific hypotheses concerning the in vivo importance of GHBP by isolated GHBP gene-deficiency using a targeted gene disruption approach. We are confident that many questions concerning the biological role of GHBP will be answered in addition to new questions being raised once the GHBP gene disrupted mouse is generated. This proposal seeks to elucidate the role of growth hormone binding protein (GHBP), a protein whose function remains largely unknown other than its ability to bind growth hormone (GH) in the blood. Unlike GHBP, the function of GH is well established and GH is known to play an important role in normal metabolism and in the progression of several diseases such as diabetes, cancer and even aging. Thus, results obtained from this proposal would not only further our understanding of GH, but could help further our understanding of complex metabolic conditions and of the processes involved in aging.