High-fat diet rescues lethality of homozygous knock-in R155H VCP myopathic mice

描述（由申请人提供）：我们实验室是第一个鉴定VCP突变是遗传性包涵体肌病、佩吉特骨病、额颞叶痴呆和肌萎缩侧索硬化症的病因的实验室，并且在鉴定这些疾病的潜在分子发病机制方面取得了进展。对患者成肌细胞和杂合子R155 H小鼠的研究已经将VCP置于泛素-蛋白酶体信号传导和自噬途径的交叉点，这两种机制被认为是导致细胞内蛋白质降解和肌肉和大脑中观察到的异常病理学的原因。我们开发了第一个携带常见R155 H突变的基因敲入VCP小鼠模型，该模型具有许多人类疾病的典型临床特征（1）。与R155 H杂合（VCPR 155 H/+）小鼠模型中的疾病进展不同，纯合子（VCPR 155 H/R155 H）具有更严重的肌肉、脑和脊髓病理学，大多数存活不超过21天。结构和功能研究表明，纯合子表现出异常的自噬途径和线粒体增殖。最近的初步研究表明，给怀孕的杂合子母鼠喂食脂肪含量增加3%的饮食，可以显著提高其纯合子后代的存活率。这些后代的寿命超过21天，并成功断奶，表明增加脂肪饮食改善了致死表型。在本申请中，我们建议研究脂肪含量的最佳百分比以进一步挽救致死表型。我们还将研究正常与高脂饮食处理的纯合子VCP基因敲入小鼠中重要的线粒体、自噬和泛素-蛋白酶体分子途径的改变。研究这一观察结果为VCP和相关疾病患者提供了一个有前途的治疗策略。 公共卫生相关性：与杂合R155 H VCP小鼠模型相比，敲入纯合VCP R155 H敲入小鼠表现出更严重的疾病，并在21天死亡。小鼠具有许多与VCP基因突变相关的遗传性包涵体肌病、骨佩吉特病、额颞叶痴呆（IBMPFD）和ALS的典型病理特征。我们最近发现，我们可以挽救致命的表型喂养怀孕的母鼠和幼崽高脂肪的饮食。该建议提供了利用敲入纯合子小鼠进行必要的临床前研究的机会，然后再评估VCP疾病患者的这种有前途的治疗方法。

DESCRIPTION (provided by applicant): Our laboratory was the first to identify VCP mutations as a cause of hereditary inclusion body myopathy, Paget's disease of bone, frontotemporal dementia and amyotrophic lateral sclerosis, and has made progress in identifying the underlying molecular pathogenesis of these diseases. Studies of patients' myoblasts and the heterozygous R155H mouse have placed VCP at the intersection of the ubiquitin-proteasome signaling and autophagy pathways, both mechanisms being considered responsible for the intracellular protein degradation and abnormal pathology seen in muscle and brain. We have developed the first knock-in VCP mouse model carrying the common R155H mutation, which has many clinical features typical of the human disease (1). Unlike disease progression in the R155H heterozygous (VCPR155H/+) mouse model, homozygotes (VCPR155H/R155H) have a more severe muscle, brain and spinal cord pathology, with most surviving no more than 21 days. Homozygotes demonstrate an abnormal autophagic pathway and mitochondrial proliferation, as evidenced by structural and functional studies. Recent preliminary studies have shown that feeding pregnant heterozygous dams a diet with a 3% increase in fat results in a dramatic improvement in the survival of their homozygous offspring. These offspring live longer than 21 days and are successfully weaned, demonstrating that an increased fat diet ameliorates the lethal phenotype. In this application, we propose to investigate the optimum percentage of fat content on further rescuing the lethal phenotype. We will also study the important altered mitochondrial, autophagy and ubiquitin-proteasome molecular pathways in the homozygous VCP knock-in mice treated with normal versus high-fat diets. Studying this observation affords the opportunity to develop a promising therapeutic strategy for patients with VCP and related diseases. PUBLIC HEALTH RELEVANCE: The knock-in homozygous VCP R155H knock-in mouse demonstrates more severe disease compared to the heterozygous R155H VCP mouse model and dies by 21 days. The mice have many of the pathological features typical of hereditary inclusion body myopathy, Paget disease of bone, frontotemporal dementia (IBMPFD) and ALS associated with mutations in the VCP gene. We have recently identified that we can rescue the lethal phenotype by feeding pregnant dams and pups a higher fat diet. This proposal offers the opportunity of utilizing the knock-in homozygous mice for the necessary preclinical studies before evaluating this promising treatment in patients with VCP disease.