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中的第一个关键步骤，是两种人类酶缺乏症（严重甲羟戊酸尿症（MA）和高免疫球蛋白D综合征（HIDS））的部位，两者均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学，以及MvK在不同细胞过程中的潜在作用。为了实现这一目标，他们利用基因陷阱方法来消融小鼠中的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患者中所见相似的高度炎症表型，但不存在在MA患者中观察到的额外神经学后遗症。具体目的是使用研究者目前的基因陷阱构建体鉴定MvK-/-小鼠胎儿丢失的胚胎学年龄，评估可能存在的结构异常并确定是否发生植入，然后通过敲入特定的人MvK错义突变产生可行的MvK-/-小鼠。基本原理是HIDS患者表现出比MA患者（对照的0-0.2%）更高的残余MvK酶活性（对照的1.4-5.7%）。因此，研究人员推测，MvK+/-动物（具有约50%的MvK+/+酶活性）可能更容易重现HIDS表型，而需要更大程度地敲低鼠MvK活性才能重现人MA表型，而不是通过基因缺失进行完全消融。该假设是，敲入特定的人MvK错义突变将产生一种活的MvK-/-小鼠，其重现了在MA患者中观察到的神经学表型和免疫疾病。研究人员将坚持队列对照设计，所有研究均采用年龄和性别匹配的对照，并将采用标准的动物饲养、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相关的病理生理学，同时提供用于表征其他自身炎症性疾病以及涉及胆固醇通路功能的单基因/复杂遗传疾病的工具。

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.