Kato Aya, Reisert Johannes, Ihara Sayoko, Yoshikawa Keiichi, Touhara Kazushige
Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo 113-8657, Japan, Present address: Kansei Laboratories, KAO Corporation, Tokyo 131-8501, Japan.
Monell Chemical Senses Center, 3500 Market Street, Philadelphia, PA 19104-3308, USA and.
Chem Senses. 2014 Nov;39(9):771-80. doi: 10.1093/chemse/bju050. Epub 2014 Oct 13.
Thousands of odors are sensed and discriminated by G protein-coupled odorant receptors (ORs) expressed in olfactory sensory neurons (OSNs). G protein-coupled receptor kinases (GRKs) may have a role in desensitization of ORs. However, whether ORs are susceptible to agonist-dependent desensitization and whether GRKs affect odorant responsiveness of OSNs are currently unknown. Here we show that GRK3 attenuated the agonist responsiveness of a specific mouse odorant receptor for eugenol (mOR-EG) upon agonist pretreatment in HEK293 cells, but GRK3 did not affect the response amplitude or the recovery kinetics upon repeated agonist stimulation. We performed electrophysiological recordings of single OSNs which expressed mOR-EG and green fluorescent protein (GFP) in the presence or absence of GRK3. The kinetics and amplitude of agonist responsiveness of individual GFP-labeled mOR-EG neurons were not significantly affected by the absence of GRK3. These results indicate that the role of GRK3 in attenuating ORs responsiveness in OSNs may have been overestimated.
嗅觉感觉神经元（OSN）中表达的G蛋白偶联气味受体（OR）能感知并区分数千种气味。G蛋白偶联受体激酶（GRK）可能在OR的脱敏过程中发挥作用。然而，OR是否易受激动剂依赖性脱敏作用影响，以及GRK是否影响OSN的气味反应性，目前尚不清楚。在此，我们表明，在HEK293细胞中，经激动剂预处理后，GRK3会减弱特定的小鼠丁香酚气味受体（mOR-EG）的激动剂反应性，但GRK3在重复激动剂刺激后并不影响反应幅度或恢复动力学。我们对在有或没有GRK3的情况下表达mOR-EG和绿色荧光蛋白（GFP）的单个OSN进行了电生理记录。GRK3的缺失并未显著影响单个GFP标记的mOR-EG神经元激动剂反应性的动力学和幅度。这些结果表明，GRK3在减弱OSN中OR反应性方面的作用可能被高估了。
