Biochemical features of primary cells from a pediatric patient with a gain-of-function ODC1 genetic mutation
Biochemical features of primary cells from a pediatric patient with a gain-of-function ODC1 genetic mutation
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DOI：
10.1042/bcj20190294
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发表时间：
2019-07-31
影响因子：
4.1
通讯作者：
Bachmann, Andre S.
中科院分区：
文献类型：
--
作者：
Schultz, Chad R.;Bupp, Caleb P.;Bachmann, Andre S.
我们最近描述了一个新的常染色体显性遗传疾病的儿科患者引起的杂合子从头突变的鸟氨酸脱羧酶1（ODC 1）基因。这种新的遗传性疾病的特征是全面发育迟缓，脱发，过度生长和畸形特征。我们假设这种新的突变（c.1342 A>T）导致ODC蛋白的C-末端截短变体，该变体对正常的蛋白酶体降解具有抗性，导致腐胺在细胞中积累。ODC（E.C. 4.1.1.17）是多胺（腐胺、亚精胺和精胺）生物合成中的限速酶，其在胚胎发生、器官发生和肿瘤发生中起关键作用。在这项研究中，我们表明，从一个3岁的患者皮肤活检的原代真皮成纤维细胞含有大量的ODC蛋白和腐胺相比，原代真皮（新生儿和成人）成纤维细胞对照细胞。重要的是，积累的ODC蛋白变体保持功能活性，因为我们使用特异性C-14放射性ODC活性测定法在原代真皮成纤维细胞（对照的12-17倍）和红细胞（RBC）（对照的125-137倍）中检测到异常高的ODC酶活性。暴露于ODC抑制剂α-二氟甲基鸟氨酸（DFMO）的原代真皮成纤维细胞的ODC活性和腐胺降低到对照组中观察到的水平，而不会对细胞形态产生不利影响或诱导细胞死亡。总之，我们的患者和潜在的其他携带类似ODC 1功能获得性突变的患者可能受益于DFMO治疗，DFMO是一种具有良好安全性的药物，可抑制体内异常高的ODC活性和腐胺水平。
We recently described a new autosomal dominant genetic disorder in a pediatric patient caused by a heterozygous de novo mutation in the ornithine decarboxylase 1 (ODC1) gene. The new genetic disorder is characterized by global developmental delay, alopecia, overgrowth, and dysmorphic features. We hypothesized that this new mutation (c.1342 A>T) leads to a C-terminal truncation variant of the ODC protein that is resistant to normal proteasomal degradation, leading to putrescine accumulation in cells. ODC (E.C. 4.1.1.17) is a rate-limiting enzyme in the biosynthesis of polyamines (putrescine, spermidine, and spermine) that plays a crucial role during embryogenesis, organogenesis, and tumorigenesis. In this study, we show that primary dermal fibroblasts derived from a skin biopsy of a 3-year-old patient contain large amounts of ODC protein and putrescine compared with primary dermal (neonatal and adult) fibroblast control cells. Importantly, the accumulated ODC protein variant remained functionally active as we detected exceptionally high ODC enzyme activity in both primary dermal fibroblasts (12-17-fold of controls) and red blood cells (RBCs) (125-137-fold of controls), using a specific C-14 radioactive ODC activity assay. Exposure of primary dermal fibroblasts to ODC inhibitor alpha-difluoromethylornithine (DFMO) reduced the ODC activity and putrescine to levels observed in controls without adversely affecting cell morphology or inducing cell death. In conclusion, our patient and potentially other patients that carry a similar ODC1 gain-of-function mutation might benefit from treatment with DFMO, a drug with a good safety profile, to suppress the exceptionally high ODC activity and putrescine levels in the body.