McConalogue K, Corvera C U, Gamp P D, Grady E F, Bunnett N W
Department of Surgery, University of California San Francisco, San Francisco, California 94143-0660, USA.
Mol Biol Cell. 1998 Aug;9(8):2305-24. doi: 10.1091/mbc.9.8.2305.
Observations in reconstituted systems and transfected cells indicate that G-protein receptor kinases (GRKs) and beta-arrestins mediate desensitization and endocytosis of G-protein-coupled receptors. Little is known about receptor regulation in neurons. Therefore, we examined the effects of the neurotransmitter substance P (SP) on desensitization of the neurokinin-1 receptor (NK1-R) and on the subcellular distribution of NK1-R, Galphaq/11, GRK-2 and -3, and beta-arrestin-1 and -2 in cultured myenteric neurons. NK1-R was coexpressed with immunoreactive Galphaq/11, GRK-2 and -3, and beta-arrestin-1 and -2 in a subpopulation of neurons. SP caused 1) rapid NK1-R-mediated increase in [Ca2+]i, which was transient and desensitized to repeated stimulation; 2) internalization of the NK1-R into early endosomes containing SP; and 3) rapid and transient redistribution of beta-arrestin-1 and -2 from the cytosol to the plasma membrane, followed by a striking redistribution of beta-arrestin-1 and -2 to endosomes containing the NK1-R and SP. In SP-treated neurons Galphaq/11 remained at the plasma membrane, and GRK-2 and -3 remained in centrally located and superficial vesicles. Thus, SP induces desensitization and endocytosis of the NK1-R in neurons that may be mediated by GRK-2 and -3 and beta-arrestin-1 and -2. This regulation will determine whether NK1-R-expressing neurons participate in functionally important reflexes.
在重组系统和转染细胞中的观察结果表明，G蛋白偶联受体激酶（GRK）和β-抑制蛋白介导G蛋白偶联受体的脱敏和内吞作用。关于神经元中的受体调节知之甚少。因此，我们研究了神经递质P物质（SP）对培养的肌间神经元中神经激肽-1受体（NK1-R）脱敏以及NK1-R、Gαq/11、GRK-2和-3以及β-抑制蛋白-1和-2亚细胞分布的影响。NK1-R与免疫反应性Gαq/11、GRK-2和-3以及β-抑制蛋白-1和-2在一部分神经元中共表达。SP导致：1）由NK1-R介导的[Ca2+]i迅速增加，这种增加是短暂的，并且对重复刺激脱敏；2）NK1-R内化到含有SP的早期内体中；3）β-抑制蛋白-1和-2从细胞质迅速且短暂地重新分布到质膜，随后β-抑制蛋白-1和-2显著重新分布到含有NK1-R和SP的内体中。在经SP处理的神经元中，Gαq/11保留在质膜上，GRK-2和-3保留在位于中央和表面的囊泡中。因此，SP诱导神经元中NK1-R的脱敏和内吞作用，这可能由GRK-2和-3以及β-抑制蛋白-1和-2介导。这种调节将决定表达NK1-R的神经元是否参与功能上重要的反射。
