PNAS：美国研发一种新技术帮助错误折叠蛋白找到正确位置

美国俄勒冈健康与科学大学的研究人员使用药物分子伴侣——作为错误折叠的蛋白质的折叠模板的药物目标特异性小分子——恢复了因为一个突变、错误折叠的细胞表面受体GnRHR而不育的雄性小鼠的生育能力。相关文章发表于2013年12月09日的《PNAS》杂志上。

PNAS：美国研发一种新技术帮助错误折叠蛋白找到正确位置

基因突变会使蛋白分子发生错误折叠，这些蛋白仍然保有功能，只不过无法到达正确的活性位点。在这种情况下，蛋白无法正常起作用，进而导致多种疾病。OHSU的研究团队利用能够进入细胞的小分子，对这些蛋白进行修正，使其成功到达正确位点发挥正常功能。这项在小鼠体内进行的研究，治愈了使小鼠雄性不育的疾病。研究人员相信，同样的技术也可以用于治疗人类。

“这一技术的应用前景很广，”领导这项研究的P. Michael Conn教授说。“因为许多人类疾病都是蛋白错误折叠引起的。药物伴侣Pharmacoperone能够挽救错误折叠的蛋白，使它们恢复正常功能，从而治疗相关疾病。用药物调节细胞内的分子运输路径，是治疗疾病的一个全新思路。”

蛋白必须精确折叠成为正确的三维结构，才能在人类细胞中执行功能。此前，人们认为错误折叠的蛋白没有功能。而Conn等人指出，这些蛋白仍有功能，只是被放在了错误的地方。当受体、离子通道和酶发生错误折叠时，会被细胞的质控系统识别，最终滞留在内质网中，或被运送到错误的位置。

研究显示，Pharmacoperone能够解决这一问题，让蛋白重新发挥作用。Pharmacoperone是能够扩散进入细胞的特异性小分子，它们可以作为折叠模板，帮助突变蛋白通过质控系统的审核，到达正确的活性位点。

Conn团队首次在活体动物中展示了Pharmacoperone的效力。他们构建了表达突变型GnRHR的小鼠模型，这种突变会使小鼠(和人)雄性不育。研究显示，药物伴侣成功帮助突变蛋白，回到细胞膜上发挥正常功能。

“我们希望这项研究能够改变制药公司筛选药物的方式，因为目前的筛选方法会错过许多有用的pharmacoperone药物。”Conn说。

错误折叠的蛋白在细胞中累积，会引起多种疾病，例如阿尔茨海默症、帕金森症和亨廷顿病等神经退行性疾病。此外，特定类型的糖尿病、遗传性白内障和囊性纤维化也与蛋白错误折叠有关。下一步，研究人员计划进入临床试验，将pharmacoperone技术用于治疗人类患者。

原文摘要：

Restoration of testis function in hypogonadotropic hypogonadal mice harboring a misfolded GnRHR mutant by pharmacoperone drug therapy

Jo Ann Janovick, M. David Stewart, Darla Jacob, L. D. Martin, Jian Min Deng, C. Allison Stewart, Ying Wang, Anda Cornea, Lakshmi Chavali, Suhujey Lopez, Shoukhrat Mitalipov, Eunju Kang, Hyo-Sang Lee, Pulak R. Manna, Douglas M. Stocco, Richard R. Behringer, and P. Michael Conn

Mutations in receptors, ion channels, and enzymes are frequently recognized by the cellular quality control system as misfolded and retained in the endoplasmic reticulum (ER) or otherwise misrouted. Retention results in loss of function at the normal site of biological activity and disease. Pharmacoperones are target-specific small molecules that diffuse into cells and serve as folding templates that enable mutant proteins to pass the criteria of the quality control system and route to their physiologic site of action. Pharmacoperones of the gonadotropin releasing hormone receptor (GnRHR) have efficacy in cell culture systems, and their cellular and biochemical mechanisms of action are known. Here, we show the efficacy of a pharmacoperone drug in a small animal model, a knock-in mouse, expressing a mutant GnRHR. This recessive mutation (GnRHR E90K) causes hypogonadotropic hypogonadism (failed puberty associated with low or apulsatile luteinizing hormone) in both humans and in the mouse model described. We find that pulsatile pharmacoperone therapy restores E90K from ER retention to the plasma membrane, concurrently with responsiveness to the endogenous natural ligand, gonadotropin releasing hormone, and an agonist that is specific for the mutant. Spermatogenesis, proteins associated with steroid transport and steroidogenesis, and androgen levels were restored in mutant male mice following pharmacoperone therapy. These results show the efficacy of pharmacoperone therapy in vivo by using physiological, molecular, genetic, endocrine and biochemical markers and optimization of pulsatile administration. We expect that this newly appreciated approach of protein rescue will benefit other disorders sharing pathologies based on misrouting of misfolded protein mutants.