Bradykinin stimulates phosphorylation of synapsin I in PC12 cells

• Published in: Japanese Journal of Pharmacology 2001, Vol.85 (suppl.1), p.231-231
• Main Authors: Hirotsugu Kato, Katsuhiko Sakurada, Yuri Ikeda, Kohji Fukunaga, Hideyuki Yamamoto, Eihichi Miyamoto, Yasuharu Sasaki
• Format: Article
• Language: Japanese
• ISSN: 0021-5198

Bradykinin (BK) is well known to induce neurotransmitter release associated with phosphorylation of synapsin I in PC12 cells. However, the underlying mechanism is not fully understood. We, therefore, examined the effect of BK on the phosphorylation of synapsin I at site 3 (Ser 603) in PC12 cells using a phosphorylation site-specific antibody of synapsin I. Treatment of PC12 cells with BK induced a transient phosphorylation of synapsin I at site 3 with maximum phosphorylation point at 15 sec. in concentration-dependent manner. The BK -induced phosphorylation was not associated with an autophosphorylation of CaM kinase II. Furthermore, KN-62 (CaM kinase II inhibitor) did not affect both phosphorylations of synapsin I and CaM kinase II. BK/B2 receptor antagonist Hoe 140, but not B1 receptor antagonist des-Arg^10 Hoe 140, inhibited the BK effect. Thapsigargin, BAPTA-AM, and depletion of extracellular Ca^2+ also inhibited the BK effect. In contrast, high K^+ -induced phosphorylation was sensitive toBAPTA-AM, depletion of extracellular Ca^2+ and KN-62, but not thapsigargin. Theses results suggest that in PC12 cells, some of BK-activated pathway for the phosphorylation of synapsin I at site 3 may be CaM kinase II-independent and different from high K^+ -activated one.