T1R1 and T1R3 are receptors expressed in taste buds that detect L-amino acids. These receptors are also expressed throughout diverse organ systems, such as the digestive system and muscle tissue, and are thought to function as amino acid sensors. The mechanism of transcriptional regulation of the mouse T1R1 gene (Tas1r1) has not been determined; therefore, in this study, we examined the function of Tas1r1 promoter in the mouse myoblast cell line, C2C12. Luciferase reporter assays showed that a 148-bp region upstream of the ATG start codon of Tas1r1 had a promoter activity. The GT box in the Tas1r1 promoter was conserved in the dog, human, mouse, and pig. Site-directed mutagenesis of this GT box significantly reduced the promoter activation. The GT box in promoters is a recurring motif for Sp/KLF family members. RNAi-mediated depletion of Sp4 and Klf5 decreased Tas1r1 expression, while overexpression of Klf5, but not Sp4, significantly increased Tas1r1 expression. The ENCODE data of chromatin immunoprecipitation and sequencing (ChIP-seq) showed that Klf5 bound to the GT box during the myogenic differentiation. Furthermore, the Klf5 knockout cell lines led to a considerable decrease in the levels of Tas1r1 expression. Collectively, these results showed that Klf5 binds to the GT box in the Tas1r1 promoter and regulates Tas1r1 expression in C2C12 cells.

中文翻译：

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Krüppel样因子5（Klf5）调节C2C12成肌细胞中小鼠T1R1氨基酸受体基因（Tas1r1）的表达。

T1R1和T1R3是在味蕾中表达的检测L-氨基酸的受体。这些受体也表达在各种器官系统中，例如消化系统和肌肉组织，并被认为是氨基酸传感器。小鼠T1R1基因（Tas1r1）的转录调控机制尚未确定。因此，在这项研究中，我们检查了小鼠成肌细胞C2C12中Tas1r1启动子的功能。萤光素酶报告基因分析表明，Tas1r1的ATG起始密码子上游的148 bp区域具有启动子活性。Tas1r1启动子中的GT盒在狗，人，小鼠和猪中是保守的。该GT盒的定点诱变显着降低了启动子的激活。启动子中的GT框是Sp / KLF家族成员的重复主题。RNAi介导的Sp4和Klf5耗竭降低了Tas1r1表达，而Klf5而不是Sp4的过表达显着增加了Tas1r1表达。染色质免疫沉淀和测序（ChIP-seq）的ENCODE数据显示，Klf5在成肌分化过程中与GT盒结合。此外，Klf5基因敲除细胞系导致Tas1r1表达水平显着下降。总的来说，这些结果表明，Klf5与Tas1r1启动子中的GT盒结合并调节Tas1r1在C2C12细胞中的表达。Klf5基因敲除细胞系导致Tas1r1表达水平显着下降。总而言之，这些结果表明，Klf5与Tas1r1启动子中的GT盒结合并调节Tas1r1在C2C12细胞中的表达。Klf5基因敲除细胞系导致Tas1r1表达水平显着下降。总而言之，这些结果表明，Klf5与Tas1r1启动子中的GT盒结合并调节Tas1r1在C2C12细胞中的表达。