Intracellular cAMP contents regulate NAMPT expression via induction of C/EBPβ in adipocytes.
Intracellular cAMP contents regulate NAMPT expression via induction of C/EBPβ in adipocytes.
复制标题
细胞内 cAMP 含量通过诱导脂肪细胞中的 C/EBPβ 来调节 NAMPT 表达。
DOI：
10.1016/j.bbrc.2019.11.165
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发表时间：
2020
期刊：
影响因子：
--
通讯作者：
Katayama S.
中科院分区：
文献类型：
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作者：
Mitani T;Watanabe S;Wada K;Fujii H;Nakamura S;Katayama S.
细胞内烟酰胺腺嘌呤单核苷酸(NAD+)的减少会导致脂肪组织功能障碍。烟酰胺磷酸核糖转移酶(NAMPT)催化NAD+生物合成途径中的限速步骤。然而，调控脂肪细胞NAMPT表达的分子机制尚不清楚。本研究发现，细胞内cAMP可调节3T3-L1脂肪细胞中NAMPT的表达和启动子活性。蛋白激酶A抑制剂H89抑制cAMP介导的NAMPT启动子活性，而AMP激活的蛋白激酶抑制剂化合物C不影响cAMP介导的NAMPT启动子活性。细胞内cAMP诱导CCAAT/增强子结合蛋白β(C/EBpβ)表达。C/eBPβ的敲除抑制了NAMPT的表达和启动子的活性。此外，C/eBPβ激活Nampt启动子，而LIP激活C/eBPβ的显性负性形式。启动子序列分析表明，C/−−β介导的启动子活性需要位于NAMPT上的启动子96-76区域。染色质免疫沉淀实验证明C/eBPβ与Nampt的启动子序列结合。最后，NAMPT抑制剂FK866抑制3T3-L1细胞的成脂作用，这种抑制作用可被烟酰胺单核苷酸处理恢复。这些结果表明，细胞内cAMP通过诱导C/EBPβ的表达而增加NAMPT的水平，提示NAMPT的表达在脂肪形成中起重要作用。
A decline in intracellular nicotinamide adenine mononucleotide (NAD+) causes adipose tissue dysfunction. Nicotinamide phosphoribosyltransferase (NAMPT) catalyzes the rate-limiting step in the NAD+biosynthesis pathway. However, the molecular mechanism that mediates regulation of NAMPT expression in adipocytes is yet to be elucidated. This study found that intracellular cAMP regulates NAMPT expression and promoter activity in 3T3-L1 adipocytes. cAMP-mediatedNamptpromoter activity was suppressed by protein kinase A inhibitor H89, whereas AMP-activated protein kinase inhibitor compound C did not affect cAMP-mediatedNamptpromoter activity. Intracellular cAMP induced CCAAT/enhancer-binding protein β (C/EBPβ) expression. Knockdown of C/EBPβ suppressed NAMPT expression and promoter activity. Furthermore, theNamptpromoter was activated by C/EBPβ, while LIP activated the dominant-negative form of C/EBPβ. Promoter sequence analysis revealed that the region from −96 to −76 onNamptwas required for C/EBPβ-mediated promoter activity. Additionally, chromatin immunoprecipitation assay demonstrated that C/EBPβ was bound to the promoter sequences ofNampt. Finally, NAMPT inhibitor FK866 suppressed adipogenesis in 3T3-L1 cells, and this suppressive effect was restored by nicotinamide mononucleotide treatment. These findings showed that intracellular cAMP increased NAMPT levels by induction of C/EBPβ expression and indicated that the induction of NAMPT expression was important for adipogenesis.