Regulation of Cardiomyocyte Glut4 Expression by ZAC1
Regulation of Cardiomyocyte Glut4 Expression by ZAC1
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DOI：
10.1074/jbc.m109.097246
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发表时间：
2010-05-28
影响因子：
4.8
通讯作者：
Swan, Kristin
中科院分区：
文献类型：
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作者：
Czubryt, Michael P.;Lamoureux, Lise;Swan, Kristin
转录因子ZAC1在包括发育中的心脏在内的多种组织中表达，但其生理作用尚不清楚。我们研究了ZAC1在调节胰岛素反应性葡萄糖转运蛋白GLUT4表达中的作用，以及ZAC1的表达是否在心肌细胞肥大中发生改变。我们分别用PCR和Western blotting证实了Zac1 mRNA和蛋白在大鼠心肌细胞中的表达。通过结合染色质免疫沉淀和荧光素酶测定，我们发现ZAC1通过Glut4启动子中的特定结合位点调节Glut4的表达。通过荧光模拟物摄取测定，ZAC1的过表达增加了Glut4 mRNA和蛋白的表达，并导致心肌细胞葡萄糖摄取增加。苯肾上腺素或异丙肾上腺素诱导肥大导致Zac1表达增加。我们在Zac1基因中发现了一个新的假定启动子，并证明MEF2在肥厚刺激下与该启动子的结合增加。MEF2调节Zac1启动子的反激活和Zac1蛋白的表达。这项工作确定了ZAC1是一种新的和以前未知的心肌细胞Glut4表达和葡萄糖摄取的调节剂。我们的研究结果还暗示MEF2在诱导肥大的过程中作为ZAC1表达的调节因子。
The transcription factor ZAC1 is expressed in a variety of tissues including the developing heart, but its physiological role is unclear. We examined the role of ZAC1 in regulating expression of the insulin-responsive glucose transporter GLUT4 and whether ZAC1 expression is altered in cardiomyocyte hypertrophy. We demonstrated expression of Zac1 mRNA and protein in rat cardiomyocytes by PCR and Western blotting, respectively. Using a combination of chromatin immunoprecipitation and luciferase assays, we showed that ZAC1 regulates Glut4 expression via a specific binding site in the Glut4 promoter. Overexpression of ZAC1 increased Glut4 mRNA and protein expression and resulted in increased glucose uptake in cardiomyocytes as determined by a fluorescent analog uptake assay. Induction of hypertrophy by phenylephrine or isoproterenol resulted in increased Zac1 expression. We identified a novel putative promoter in the Zac1 gene and demonstrated increased binding of MEF2 to this promoter in response to hypertrophic stimulation. MEF2 regulated transactivation of the Zac1 promoter and ZAC1 protein expression. This work identifies ZAC1 as a novel and previously unknown regulator of cardiomyocyte Glut4 expression and glucose uptake. Our results also implicate MEF2 as a regulator of ZAC1 expression in response to induction of hypertrophy.