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) 在激动剂刺激下会发生功能和分布变化，即受体脱敏/内化。 G 蛋白偶联受体激酶 (GRK) 对激动剂占据的 GPCR 进行磷酸化是诱导受体脱敏和随后抑制蛋白介导的内化的关键事件。然而，与Gq蛋白家族（例如组胺H_1受体（H_1Rs））偶联的Ca^2+受体的脱敏/内化机制的研究要少得多，特别是通过Ca^2+对脱敏/内化过程的反馈调节我们研究了人U373中Ca^2+（CaM）介导的H_1Rs调节 MG星形细胞瘤细胞，并发现激动剂诱导的、网格蛋白介导的H_1R内化的发生被Ca^2+/CaM的激活延迟，这可能是由于GRK介导的内化过程的抑制。虽然由于Ca^2+/CaM介导的受体内化抑制而使H_1R保留在细胞表面膜上，但Ca^2+/CaM通过激活CaM激酶II（用于脱敏）和蛋白磷酸酶2B（用于再敏化）来调节对细胞表面H_1R的激动剂亲和力。即使在激动剂存在下细胞内Ca 2+ 浓度的随后降低也可以允许H_1R被内化。相反，由Ca 2+ 离子载体、离子霉素引起的非受体介导的细胞内Ca 2+ 持续增加未能抑制组胺介导的H_1R内化。因此，表明Ca 2+ /CaM的受体介导的激活在通过调节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发挥关键作用。

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。