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: 12672129
• 负责人: HISHINUMA Shigeru
• 金额: $ 2.18万
• 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: 2000
• 资助国家: 日本
• 起止时间: 2000 至 2001
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-12672129/
• 关键词: ASTROCYTOMA CELL; HTSTAMINE HI RECEPIOR; DESENSITIZATION; RESENSITIZATION; RECEPTOR INTFRNALIZAT1ON; BINDING AFFINITY; CALMODULIN; CaM KINASE II; CALCINEURIN; ヒスタミンH1受容体; 受容体親和性

Many G protein-coupled receptors (GPCRs) undergo functional and distributional changes on 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+>-mobilizing receptors coupled to the Gq family of G proteins, such as histamine H_1, receptors (H_1,Rs), has been much less studied, in particular, with respect to feedback modulation of the desensitization/internalization process via the Ca^<2+> signaling. We have found in human U373 MG astrocytoma cells that agonist-induced, clathrin-mediated internalization of H_1Rs is transiently inhibited by Ca^<2+>/calmodulin (CaM), where neither Ca^<2+>/CaM-dependent enzymes, such as CaM kinase II and calcineurin (PP2B), nor protein kinase C (PKCs) is involved. Since Ca^<2+>/CaM is known to inhibit receptor Phosphorylation by GRKs, this might be responsible for the Ca^<2+>/CaM-mediated inhibition of receptor internalization. As a result, H_1Rs remain on the cell surface membrane during the early stage of agonist stimulation. In contrast to the receptor internalization, the affinity of histamine for the H,Rs was dually regulated by desensitizing CaM kinase II and resensitizing PP2B before initiation of the receptor internalization. The subsequent decrease in the intracellular Ca^<2+> concentration even in the presence of agonist may allow H_1Rs to be internalized, and the internalized receptors showed a reduced affinity for histamine. Thus, it is suggested that Ca^<2+>/CaM play 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）在激动剂刺激下发生功能和分布变化，即，受体的脱敏/内化。G蛋白偶联受体激酶（GRKs）对激动剂占据的GPCR的磷酸化是诱导受体脱敏和随后的抑制蛋白介导的内化的关键事件。然而，与G蛋白Gq家族偶联的Ca^2+动员受体，如组胺H_1受体（H_1，Rs）的脱敏/内化机制研究较少，特别是关于通过Ca^2+信号传导对脱敏/内化过程的反馈调节。我们在人U373 MG星形细胞瘤细胞中发现，激动剂诱导的网格蛋白介导的H_1受体内化被Ca^2+/钙调蛋白（CaM）短暂抑制，其中既不涉及Ca^2 +/CaM依赖性酶，如CaM激酶II和钙调神经磷酸酶（PP 2B），也不涉及蛋白激酶C（PKC）。由于已知Ca^2+/CaM可抑制GRKs对受体的磷酸化，这可能是Ca^2+/CaM介导的受体内化抑制的原因。因此，在激动剂刺激的早期阶段，H_1Rs保留在细胞表面膜上。与受体内化相反，组胺对H，Rs的亲和力在受体内化开始之前通过脱敏CaM激酶II和重新敏化PP 2B进行双重调节。即使在激动剂存在的情况下，细胞内Ca^2+浓度也随之降低，这可能使H_1受体被内化，而内化的受体对组胺的亲和力降低。因此，Ca^<2+>/CaM通过调节CaM激酶II、PP 2B和GRKs的活性，在决定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

Hishinuma, S.: "Ca^<2+>/calmodulin-mediated regulation of desensitization and internalization of G_q protein-coupled histamine H_1 receptors"Recent Research Developments in Neurochemistry. 3. 215-230 (2000)

Hishinuma，S.：“Ca ^ 2 /钙调蛋白介导的G_q蛋白偶联组胺H_1受体的脱敏和内化调节”神经化学的最新研究进展。

Shigeru Hishinuma: "Ca^<2+>/calmodulin-mediated regulation of the desensitizing process in G_q protein-coupled histamine H_1 receptor-mediated Ca^<2+> responses in human U373 MG astrocytoma cells"Journal of Neurochemistry. 75. 772-781 (2000)

Shigeru Hishinuma：“人U373 MG星形细胞瘤细胞中G_q蛋白偶联组胺H_1受体介导的Ca ^ 2 反应中Ca ^ 2 /钙调蛋白介导的脱敏过程调节”神经化学杂志。

Shigeru Hishinuma: "Internalization-mediated regulation of the affinity of histamine for G_q protein-coupled histamine H_1 receptors in human U373 MG astrocytoma cells"Japanese Journal of Pharmacology. 88(Suppl.l). 211 (2002)

Shigeru Hishinuma：“人 U373 MG 星形细胞瘤细胞中组胺对 G_q 蛋白偶联组胺 H_1 受体亲和力的内化介导调节”《日本药理学杂志》。

Hishinuma, S. and Saito, M.: "Internalization-mediated regulation of the affinity of histamine for G_q protein-coupled histamine H_1 receptors in human U373 MG astrocytoma cells"Japanese Journal of Pharmacology. 88 (Suppl. I). 211 (2002)

Hishinuma, S. 和 Saito, M.：“人 U373 MG 星形细胞瘤细胞中组胺对 G_q 蛋白偶联组胺 H_1 受体亲和力的内化介导调节”《日本药理学杂志》。

Shigeru Hishinuma: "Agonist-mediated regulation of histamine H_1 receptors and Ca^<2+> signaling : Ca^<2+>/calmodulin-mediated requlation of receptor function and distribution"Program & Abstract for International Sendai Histamine Symposium. 122 (2000)

Shigeru Hishinuma：“组胺 H_1 受体和 Ca^2 > 信号传导的激动剂介导的调节：Ca^2/钙调蛋白介导的受体功能和分布的调节”计划