INVESTIGATION OF DESENSITIZATION/RESENSITIZATION MECHANISMS FOR Gq PROTEIN-COUPLED RECEPTORS

Gq 蛋白偶联受体脱敏/再敏机制的研究

• 批准号: 14572078
• 负责人: HISHINUMA Shigeru
• 金额: $ 1.92万
• 依托单位: MEIJI PHARMACEUTICAL UNIVERSITY
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 2002
• 资助国家: 日本
• 起止时间: 2002 至 2003
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-14572078/
• 关键词: ASTROCYTOMA CELL; HISTAMINE HI RECEPTOR; DESENSITIZATION; RESENSITIZXTlON; RECEPTOR INTERNALIZATION; BINDING AFFINITY; CALMODULIN; CaM KINASE II; CALCINEURIN; CadキナーゼII

Many G protein-coupled receptors (GPCRs) undergo functional and distributional changes upon stimulation with agonist, i.e., desensitization/internalization of receptors. Phosphorylation of agonist-occupied GPCRs by G protein-coupled receptor kinases (GRKs) is a key event for induction of receptor desensitization and the subsequent arrestin-mediated internalization. However, desensitization/internalization mechanisms of Ca^<2+> receptors coupled to the Gq family of G proteins, such as histamine H_1 receptors (H_1Rs), has been much less studied, in particular, with respect to feedback modulation of the desensitization/internalization process via the Ca^<2+> We investigated Ca~<2+> (CaM)-mediated regulation of H_1Rs in human U373 MG astrocytoma cells, and found that the onset of agonist-induced, clathrin-mediated internalization of H_1Rs was delayed by activation of Ca^<2+>/CaM, possibly due to inhibition of GRK-mediated internalization process. While the H_1Rs remained on the cell surface membrane owing to the Ca^<2+>/CaM-mediated inhibition of receptor internalization, the agonist affinity for the cell surface H_1Rs was regulated by Ca^<2+>/CaM via actiyation of CaM kinase II (for desensitization) and protein phosphatase 2B (for resenisitization). The subsequent decrease in the intracellular Ca^<2+> concentration even in the presence of agonist may allow H_1Rs to be internalized. In contrast, a receptor-non-mediated and sustained increase in the intracellular Ca^<2+> by a Ca^<2+> ionophore, ionomycin, failed to inhibit histamine-mediated internalization of H_1Rs. Thus, it is suggested that the receptor-mediated activation of Ca^<2+>/CaM plays a crucial role in determining both function and distribution of Gq protein-coupled receptors by regulating activity of CaM kinase II, PP2B and GRKs.

许多G蛋白偶联受体（GPCR）在用激动剂（即受体的脱敏/内在化）刺激后会发生功能和分布变化。 G蛋白偶联受体激酶（GRKS）对激动剂占用的GPCR的磷酸化是诱导受体脱敏和随后的抑制素介导的内在化的关键事件。但是，Ca^<2+>受体的脱敏/内部化机制与GQ蛋白的GQ家族（例如组胺H_1受体（H_1RS））相结合的研究少于研究，特别是在通过CA^<2+>的脱敏化/内部化过程中的反馈调节，我们研究了CA^<2+> <2+ <2+ <2+> - MG星形细胞瘤细胞，发现激动剂诱导的，网格蛋白介导的H_1RS的内在化的发作通过CA^<2+>/CAM的激活延迟，这可能是由于抑制了GRK介导的内在化过程。由于Ca^<2+>/CAM介导的受体内在化抑制了CA^<2+>/介导的h_1RS，但通过CA^<2+>/cAM通过CAM激酶II的作用（用于脱发）和蛋白质磷酸酶2B（有效的蛋白质磷酸酶2B（有效）。随后的细胞内Ca^<2+>浓度的降低，即使在存在激动剂的情况下，也可以允许H_1RS内部化。相比之下，通过Ca^<2+>离子载体Ionymycin Ionymycin未能抑制组胺介导的H_1R的内在化，受体介导的介导并持续增加了细胞内Ca^<2+>。因此，提出受体介导的Ca^<2+>/CAM的激活在通过调节CAM激酶II，PP2B和GRK的活性来确定GQ蛋白偶联受体的功能和分布中起着至关重要的作用。

项目成果

Yuko Sato: "Effects of a Ca^<2+> ionophore, ionomycin, on histamine-induced internalization of Gq protein-coupled histamine H_1 receptors in human U373 MG astrocytoma cells."Journal of Pharmacological Sciences. 91(Suppl.I). 248 (2003)

Yuko Sato：“Ca^2离子载体、离子霉素对人U373 MG星形细胞瘤细胞中组胺诱导的Gq蛋白偶联组胺H_1受体内化的影响。”药理学科学杂志。

Shigeru Hishinuma: "Desensitization and internalization of Gq protein-coupled histamine H_1 receptors."Journal of Pharmacological Sciences. 94(Suppl.I). 22 (2004)

Shigeru Hishinuma：“Gq 蛋白偶联组胺 H_1 受体的脱敏和内化。”药理学杂志。

Hishinuma, S.: "Desensitization and internalization of Gq protein-coupled histamine H_1 receptors."J. Pharmacol. Sci.. 94 (Suppl. I). 22 (2004)

Hishinuma, S.：“Gq 蛋白偶联组胺 H_1 受体的脱敏和内化。”J.

Sato, Y.: "Regulation of the affinity of histamine for histamine H_1 receptors by the jonomycin-induced increase in intracellular Ca^<2+> concentration in human U373 MG astrocytoma cells."J. Pharmacol. Sci.. 94 (Suppl. I). 282 (2004)

Sato，Y.：“通过乔诺霉素诱导人 U373 MG 星形细胞瘤细胞内 Ca^2 浓度增加来调节组胺对组胺 H_1 受体的亲和力。”J.

Yuko Sato: "Regulation of the affinity of histamine for histamine H_1 receptors By the ionomycin-induced increase in intracellular Ca^<2+> concentration in human U373 MG astrocytoma cells"Journal of Pharmacological Sciences. 94(Suppl.I). 282 (2004)

Yuko Sato：“通过离子霉素诱导人U373 MG星形细胞瘤细胞内Ca ^ 2 浓度增加来调节组胺对组胺H_1受体的亲和力”药理学杂志。