ATP-citrate lyase deficiency in the mouse
ATP-citrate lyase deficiency in the mouse
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DOI：
10.1074/jbc.m310512200
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发表时间：
2004-03-05
影响因子：
4.8
通讯作者：
Young, SG
中科院分区：
文献类型：
--
作者：
Beigneux, AP;Kosinski, C;Young, SG
ATP-柠檬酸裂解酶 (Acly) 是合成乙酰辅酶 A (CoA) 的两种胞质酶之一。由于乙酰辅酶A是胆固醇和甘油三酯的重要组成部分，因此Acly被认为是高脂血症和肥胖症的治疗靶点。为了定义Acly缺陷小鼠的表型，我们创建了Acly基因敲除小鼠，其中β-半乳糖苷酶标记物由Acly调节序列表达。我们还试图定义 Acly 的细胞类型特异性表达模式，以进一步阐明该酶的体内作用。纯合 Acly 基因敲除小鼠在发育早期死亡。尽管 Acly mRNA 和蛋白质的表达量只有正常量的一半，但杂合子小鼠在进食和高脂肪饮食下均健康、具有生育能力且血脂正常。来自杂合子 Acly 小鼠的成纤维细胞和肝细胞含有正常量一半的 Acly mRNA 和蛋白质，但这不会干扰甘油三酯和胆固醇的合成或由甾醇调节元件结合蛋白调节的脂质生物合成基因的表达。乙酰辅酶A合成酶1（另一种产生乙酰辅酶A的胞质酶）的表达没有上调。通过β-半乳糖苷酶染色判断，Acly 普遍表达，但在脂肪生成水平高的组织中表达特别高，例如在高碳水化合物饮食的小鼠肝脏中。 β-半乳糖苷酶染色在发育中的大脑中很强烈，这与组织的高水平从头脂肪生成一致。在成人大脑中，β-半乳糖苷酶染色通常要低得多，这与脂肪生成水平的降低一致。然而，β-半乳糖苷酶在胆碱能神经元中的表达仍然非常高，这可能反映了 Acly 在生成乙酰辅酶A以促进乙酰胆碱合成中的重要性。 Acly 敲除等位基因可用于识别对乙酰辅酶 A 合成有较高需求的细胞类型。
ATP-citrate lyase (Acly) is one of two cytosolic enzymes that synthesize acetyl-coenzyme A (CoA). Because acetyl-CoA is an essential building block for cholesterol and triglycerides, Acly has been considered a therapeutic target for hyperlipidemias and obesity. To define the phenotype of Acly-deficient mice, we created Acly knockout mice in which a beta-galactosidase marker is expressed from Acly regulatory sequences. We also sought to define the cell type-specific expression patterns of Acly to further elucidate the in vivo roles of the enzyme. Homozygous Acly knockout mice died early in development. Heterozygous mice were healthy, fertile, and normolipidemic on both chow and high fat diets, despite expressing half-normal amounts of Acly mRNA and protein. Fibroblasts and hepatocytes from heterozygous Acly mice contained half-normal amounts of Acly mRNA and protein, but this did not perturb triglyceride and cholesterol synthesis or the expression of lipid biosynthetic genes regulated by sterol regulatory element-binding proteins. The expression of acetyl-CoA synthetase 1, another cytosolic enzyme for producing acetylCoA, was not up-regulated. As judged by beta-galactosidase staining, Acly was expressed ubiquitously but was expressed particularly highly in tissues with high levels of lipogenesis, such as in the livers of mice fed a high-carbohydrate diet. beta-Galactosidase staining was intense in the developing brain, in keeping with the high levels of de novo lipogenesis of the tissue. In the adult brain, beta-galactosidase staining was in general much lower, consistent with reduced levels of lipogenesis; however, beta-galactosidase expression remained very high in cholinergic neurons, likely reflecting the importance of Acly in generating acetyl-CoA for acetylcholine synthesis. The Acly knockout allele is useful for identifying cell types with a high demand for acetyl-CoA synthesis.