Murine Knockout Model of Mevalonic Aciduria

描述（来自申请）：甲羟戊酸激酶（MvK）催化胆固醇和异戊二烯合成的第一步，是两种人类酶缺乏的位点，严重的甲羟戊酸尿症（MA）和高免疫球蛋白D综合征（HIDS），两者都表现为自身炎症性疾病。研究人员的长期目标是了解与MA和HIDS相关的多效性病理生理，以及MvK在多种细胞过程中的潜在作用。为了实现这一目标，他们利用了一种基因诱捕方法来清除小鼠中的MvK。尽管MvK-/-小鼠似乎在胚胎期死亡，但MvK+/-小鼠存活并表现出与HIDS和MA患者相似的高炎症表型，但没有MA患者观察到的额外神经系统后遗症。具体目的是使用研究者目前的基因陷阱构建确定MvK-/-小鼠胎儿丢失的胚胎年龄，评估可能存在的结构异常并确定是否发生着床，然后通过敲入特定的人类MvK错义突变来产生活的MvK-/-小鼠。理由是HIDS患者表现出更高的残留MvK酶活性（占对照组的1.4-5.7%），而MA患者（占对照组的0-0.2%）。因此，研究人员推测MvK+/-动物（具有约50%的MvK+/+酶活性）可能更容易再现HIDS表型，而再现人类MA表型需要更大程度的敲除小鼠MvK活性，而不是通过基因缺失完全消除。假设是敲入特定的人类MvK错义突变将产生可存活的MvK-/-小鼠，再现在MA患者中观察到的神经表型和免疫疾病。研究者将坚持队列控制设计，对所有研究采用年龄和性别匹配的对照，并将采用标准的畜牧业、胚胎分离和表征以及基因靶向方法。MvK+/-和MvK-/-小鼠将有助于揭示与MA和HIDS相关的病理生理，同时为其他自身炎症疾病以及涉及胆固醇途径功能的单基因/复杂遗传疾病的表征提供工具。

DESCRIPTION (from the application): Mevalonate kinase (MvK) catalyzes the first committed step in cholesterol and isoprene synthesis, and is the site of two human enzyme deficiencies, severe mevalonic aciduria (MA) and hyperimmunoglobulin D syndrome (HIDS), both manifesting autoinflammatory disease. The investigators' long-term objective is to understand the pleiotropic pathophysiology associated with MA and HIDS, and the potential role of MvK in diverse cellular processes. To work toward this objective, they have utilized a gene-trap approach to ablate MvK in the mouse. Whereas MvK-/- mice appear to die embryonically, MvK+/- mice survive and manifest a hyperinflammatory phenotype reminiscent of that seen in both HIDS and MA patients, but absent the additional neurological sequelae observed in MA patients. The specific aim is to identify the embryological age of fetal loss for MvK-/- mice using the investigators' current gene-trap construct, assess structural anomalies that might be present and determine whether implantation occurs, and then generate a viable MvK-/- mouse via knock-in of specific human MvK missense mutations. The rationale is that HIDS patients manifest higher residual MvK enzyme activity (1.4-5.7% of control) than MA patients (0-0.2% of control). Thus, the investigators speculate that MvK+/- animals (with ~50% of MvK+/+ enzyme activity) might more readily recapitulate the HIDS phenotype, whereas it will require greater knock-down of murine MvK activity to recapitulate the human MA phenotype, but not total ablation via gene deletion. The hypothesis is that knock-in of specific human MvK missense mutations will produce a viable MvK-/- mouse that recapitulates the neurological phenotype and immune disease observed in MA patients. The investigators will adhere to a cohort control design, with age- and gender-matched controls for all studies, and will employ standard methods of animal husbandry, embryo isolation and characterization, and gene targeting. MvK+/- and MvK-/- mice will help unravel pathophysiology associated with MA and HIDS, while providing tools for characterization of other autoinflammatory disorders as well as monogenic/complex genetic diseases in which cholesterol pathway function has been implicated.