Glutamine-induced signaling pathways via amino acid receptors in enteroendocrine L cell lines
Glutamine-induced signaling pathways via amino acid receptors in enteroendocrine L cell lines
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DOI：
10.1530/jme-19-0260
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发表时间：
2020-04-01
影响因子：
3.5
通讯作者：
Tsuboi, Takashi
中科院分区：
文献类型：
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作者：
Nakamura, Takumi;Harada, Kazuki;Tsuboi, Takashi
胰升糖素样肽-1(GLP-1)由胃肠内分泌的L细胞分泌，可诱导胰岛素分泌，对维持血糖稳态起重要作用。GLP-1的分泌是由包括氨基酸在内的各种腔内营养物质诱导的。细胞内钙离子和cAMP动力学在GLP-1的分泌调节中起着重要作用；然而，氨基酸诱导GLP-1分泌的潜在机制的几个方面还没有得到很好的描述。我们研究了L-谷氨酰胺诱导小鼠肠内分泌L细胞内钙离子和cAMP浓度(分别为[Ca~(2+)](I)和[cAMP](I))升高的机制。在细胞外低[Na+]条件下应用L-谷氨酰胺抑制钠偶联L-谷氨酰胺转运体的功能，不能引起细胞内[Ca~(2+)]~(2+)升高。G蛋白偶联受体家族6成员A和钙敏感受体拮抗剂对[Ca~(2+)](I)和[cAMP](I)无明显影响，而味觉受体1成员3(TAS1R3)拮抗剂可抑制[cAMP](I)的升高。为了阐明TAS1R3的功能，TAS1R3与味觉受体1成员1(TAS1R1)形成异二聚体，我们用CRISPR/Cas9系统建立了TAS1R1和TAS1R3突变的GLUTag细胞。TAS1R1突变型GLUTag细胞表现出L-谷氨酰胺诱导的[cAMP](I)升高，而部分TAS1R3突变型GLUTag细胞不表现出L-谷氨酰胺诱导的[cAMP](I)和GLP-1分泌增加。提示TAS1R3在L谷氨酰胺诱导的[cAMP](I)和GLP-1分泌增加中起重要作用。因此，TAS1R3可能与Gs偶联，并与cAMP调节有关。
Glucagon-like peptide-1 (GLP-1), secreted by gastrointestinal enteroendocrine L cells, induces insulin secretion and is important for glucose homeostasis. GLP-1 secretion is induced by various luminal nutrients, including amino acids. Intracellular Ca2+ and cAMP dynamics play an important role in GLP-1 secretion regulation; however, several aspects of the underlying mechanism of amino acid-induced GLP-1 secretion are not well characterized. We investigated the mechanisms underlying the L-glutamine-induced increase in Ca2+ and cAMP intracellular concentrations ([Ca2+](i) and [cAMP](i), respectively) in murine enteroendocrine L cell line GLUTag cells. Application of L-glutamine to cells under low extracellular [Na+] conditions, which inhibited the function of the sodium-coupled L-glutamine transporter, did not induce an increase in [Ca2+](i). Application of G proteincoupled receptor family C group 6 member A and calcium-sensing receptor antagonist showed little effect on [Ca2+](i) and [cAMP](i); however, taste receptor type 1 member 3 (TAS1R3) antagonist suppressed the increase in [cAMP](i). To elucidate the function of TAS1R3, which forms a heterodimeric umami receptor with taste receptor type 1 member 1 (TAS1R1), we generated TAS1R1 and TAS1R3 mutant GLUTag cells using the CRISPR/ Cas9 system. TAS1R1 mutant GLUTag cells exhibited L-glutamine-induced increase in [cAMP](i), whereas some TAS1R3 mutant GLUTag cells did not exhibit L-glu tamine-induced increase in [cAMP](i) and GLP-1 secretion. These findings suggest that TAS1R3 is impo rtant for L-glutamine-induced increase in [cAMP](i) and GLP-1 secretion. Thus, TAS1R3 may be coupled with Gs and related to cAMP regulation.