廣東型 G6PD 突變的小鼠產生肥胖、胰島素阻抗性、葡萄糖耐受不良與脂肪肝

Mice carrying G6PD Canton mutation develop obesity, insulin resistance, glucose intolerance, and fatty liver

劉育如(Yu-Ju Liu)

指導教授 ： 張以承

國立臺灣大學/醫學院/分子醫學研究所/碩士(2021年)

https://doi.org/10.6342/NTU202101067

摘要

在全球約有4 億人有glucose-6-phosphate dehydrogenase (G6PD)基因變異，G6PD 突變是世界第二的常見單基因突變。位置在Ｘ染色體遠端長臂的一組基因座(Xq28）。缺乏G6PD 使細胞無法產出足夠的nicotinamide adenine dinucleotide phosphate(NADPH)，伴隨reduced glutathione (GSH)降低，使氧化壓力增加。紅血球方面G6PD 的缺乏很容易氧化造成溶血。在台灣，估計大約有1.61%（男生2.81%，女生0.70%）人口帶有G6PD 基因突變, 其中以c.1376G>T(p.R459L)的點突變(廣東型蠶豆症）最常見。
在一篇統合型研究中中，G6PD 缺乏可能會導致罹患糖尿病風險增加。大規模的第二型糖尿病基因掃描也發現G6PD 基因變異會引起糖尿病，因此我們以小鼠模型驗證，發現相對於人類只有一個G6PD 基因, 小鼠有兩個同源G6PD 基因，一條在X 性染色體及另一條在第5 條染色體上的G6pd2。為模擬台灣常見廣東型蠶豆症，本實驗使用CRISPR-Cas9 系統在G6pdx 中產生G>T 的點突變及在小鼠第二條染色體剔除G6pd2，產生G6PD 雙突變的小鼠。
我們發現G6PD 雙突變小鼠餵食高脂高蔗糖飼料相對於對照組小鼠，體重上升，胰島素阻抗性增加、葡萄糖耐受性減少、脂肪肝增加、並可能產生血脂異常與腎功能異常，伴隨脂肪細胞肥大。藉由血液抹片與血球計數發現並非溶血造成、我們探討G6PD 雙突變的老鼠肥胖原因，發現其能量消耗減少為主要原因。

關鍵字

6-磷酸葡萄糖脫氫酶缺乏症 ； 氧化壓力 ； 胰島素阻抗性 ； 肥胖 ； 葡萄糖耐受性 ； 脂肪肝

並列摘要

Approximately 400 million people carry mutations in the glucose 6-phosphate dehydrogenase (G6PD) gene, and G6PD mutation is the second most prevalent genetic mutation in the world. This gene is located in the long arm of the distal end of the X chromosome (Xq28).Cells with G6PD deficiency do not produce enough nicotinamide adenine dinucleotide phosphate (NADPH), have reduced glutathione peroxidase (GSH) and increased oxidative stress.G6PD-deficient erythrocytes are particularly susceptible to oxidative insults and are at risk of for hemolysis. In Taiwan,it is estimated that there are about 1.61 %, with the most common mutationc.1376G>T(p.R459L) being Canton type (46.8%).
In a meta-anlysis of observational studies, human carrying G6PD deficiency have an increased risk of diabetes. Here, we develop knockin mice carrying the mutation mimicking human G6PD Canton mutation. In addition to human who have only one G6PD gene in the X chromosome, mice have an additional homologous G6pd2 gene in chromosome 5. To mimick the Canton-type mutation, we used the CRISPR-Cas9 system to generate a G>T mutation in G6pdx and knockout G6pd2 on mouse chromosome 5, resulting in mice with G6pd double mutations.
We found that G6pd double mutant mice fed high-fat high-sucrose diet have increased body weight, increased insulin resistance, impaired glucose tolerance, and more severe fatty liver compared with control mice with hypertrophic adipocytes.These mice also showed a trend of worsened renal function and lipid profile. We explored the causes of obesity in mice with G6PD double mutations, and found that these mice have reduced energy expenditure, which may be the major cause of weightgain. These changes were not related to hemolysis.

並列關鍵字

6-phosphate glucose dehydrogenase deficiency ； oxidative stress ； obesity ； insulin resistance ； glucose intolerance ； fatty liver

參考文獻

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