Phosphoinositide 3-kinase-dependent and -independent activation of the small GTPase Rac2 in human neutrophils

Takashi Akasaki, Hirofumi Koga, Hideki Sumimoto

研究成果: ジャーナルへの寄稿学術誌査読

155 被引用数 (Scopus)


The small GTPase Rac participates in various cellular events such as cytoskeletal reorganization. It has remained, however, largely unknown about intracellular signaling pathways for Rac activation because of the lack of a simple and reliable assay to estimate the activation. Here we describe a novel method to detect the GTP-bound, active Rac in cells by pulling it down with the Rac-binding domain of the protein kinase PAK. Experiments using this method reveal that stimulation of human neutrophils with the G(i)-coupled receptor agonists N-formyl-methionyl-leucyl-phenylalanine (fMLP) and leukotriene B4 (LTB4) leads to a rapid and transient increase in the GTP- bound state of Rac2, whereas phorbol myristate acetate (PMA) causes a slow but more sustained activation of Rac2. Pretreatment of cells with pertussis toxin results in defective activation of Rac2 in response to fMLP and LTB4, indicating that coupling of the receptors to G(i) plays a crucial role in the activation. Furthermore, the phosphoinositide 3-kinase (PI3K) inhibitors wortmannin and LY294002 block Rac2 activation elicited by the receptor agonists, but not that by PMA. Thus the G(i)-coupled receptors likely mediate Rac2 activation via PI3K, whereas PMA activates Rac2 in a PI3K-independent manner.

ジャーナルJournal of Biological Chemistry
出版ステータス出版済み - 6月 18 1999

!!!All Science Journal Classification (ASJC) codes

  • 生化学
  • 分子生物学
  • 細胞生物学


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