Glucose and cAMP regulate the L-type pyruvate kinase gene by phosphorylation/dephosphorylation of the carbohydrate response element binding protein
Glucose and cAMP regulate the L-type pyruvate kinase gene by phosphorylation/dephosphorylation of the carbohydrate response element binding protein
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DOI：
10.1073/pnas.231370798
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发表时间：
2001-11-20
影响因子：
11.1
通讯作者：
Uyeda, K
中科院分区：
文献类型：
--
作者：
Kawaguchi, T;Takenoshita, M;Uyeda, K
最近，我们从大鼠肝脏中纯化并鉴定了一个与L型丙酮酸激酶(L-PK)基因的糖反应元件结合的未知转录因子。该因子被命名为碳水化合物反应元件结合蛋白(ChREBP)。ChREBP是L-PK基因转录所必需的，被高糖激活，而被cAMP抑制。在这里，我们证明了：(1)核定位信号和ChREBP的基本螺旋-环-螺旋/亮氨酸拉链结构域是转录所必需的，(FI)这些结构域是cAMP和葡萄糖调节的靶标。在cAMP依赖的3个蛋白激酶磷酸化位点中，Ser(196)和Thr(666)是靶点。前者的磷酸化导致核输入失活，后者的磷酸化导致DNA结合活性和L-PK转录的丧失。另一方面，葡萄糖通过胞浆中丝氨酸(196)的去磷酸化激活核输入，也通过胞核中苏氨酸(666)的去磷酸化来激活DNA结合活性。这些结果揭示了过量碳水化合物和cAMP对ChREBP和L-PK转录的调控机制。
Recently we purified and identified a previously uncharacterized transcription factor from rat liver binding to the carbohydrate responsive element of the L-type pyruvate kinase (L-PK) gene. This factor was named carbohydrate responsive element binding protein (ChREBP). ChREBP, essential for L-PK gene transcription, is activated by high glucose and inhibited by cAMP. Here, we demonstrated that (i) nuclear localization signal and basic helix-loop-helix/leucine-zipper domains of ChREBP were essential for the transcription, and (fi) these domains were the targets of regulation by cAMP and glucose. Among three cAMP-dependent protein kinase phosphorylation sites, Ser(196) and Thr(666) were the target sites. Phosphorylation of the former resulted in inactivation of nuclear import, and that of the latter resulted in loss of the DNA-binding activity and L-PK transcription. On the other hand, glucose activated the nuclear import by dephosphorylation of Ser(196) in the cytoplasm and also stimulated the DNA-binding activity by dephosphorylation of Thr(666) in the nucleus. These results thus reveal mechanisms for regulation of ChREBP and the L-PK transcription by excess carbohydrate and cAMP.