TY - JOUR
T1 - Distinct roles of small GTPases RAC1 and RAC2 in histamine H4 receptor–mediated chemotaxis of mast cells
AU - Kuramasu, Atsuo
AU - Wakabayashi, Mie
AU - Inui, Makoto
AU - Yanai, Kazuhiko
N1 - Funding Information:
This work was supported in part by a Grant-in-Aid for Scientific Research (B) from the Japan Society for the Promotion of Science [Grant 19390061]. https://doi.org/10.1124/jpet.118.249706.
Funding Information:
We acknowledge the technical expertise of The DNA Core facility of the Center for Gene Research, Yamaguchi University, supported by a grant-in-aid from the Ministry of Education, Science, Sports and Culture of Japan. We also thank Shin-ichiro Kanno for technical assistance in nano-liquid chromatography–tandem mass spectrometry analysis and Editage (www.editage.jp) for English language editing.
PY - 2018/10
Y1 - 2018/10
N2 - Histamine induces chemotaxis of mast cells through the H4 receptor. However, little is known about the precise intracellular signaling pathway that mediates this process. In this study, we identified small GTPases Rac1 and Rac2 as intracellular binding partners of the H4 receptor and characterized their roles in H4 receptor signaling. We showed that histamine induced Rac GTPase activation via the H4 receptor. A Rac inhibitor NSC23766 attenuated chemotaxis of mast cells toward histamine, as well as histamine-induced calcium mobilization and extracellular signal-regulated kinase (ERK) activation. Histamine-induced migration of mast cells was also sensitive to PD98059, an inhibitor of the mitogen-activated protein kinase kinase, indicating that the Rac-ERK pathway was involved in chemotaxis through the H4 receptor. Inhibition of phosphatidylinositol-4,5-bisphosphate 3-kinase (PI3K) by LY294002 suppressed the histamine-induced chemotaxis and activation of Rac GTPases, suggesting that PI3K regulates chemotaxis upstream of Rac activation. Specific knockdown of Rac1 and Rac2 by short-hairpin RNA revealed that both Rac GTPases are necessary for histamine-induced migration. Downregulation of Rac1 and Rac2 led to attenuated response in calcium mobilization and ERK activation, respectively. These observations suggested that Rac1 and Rac2 have distinct and essential roles in intracellular signaling downstream of H4 receptor-PI3K in histamine-induced chemotaxis of mast cells.
AB - Histamine induces chemotaxis of mast cells through the H4 receptor. However, little is known about the precise intracellular signaling pathway that mediates this process. In this study, we identified small GTPases Rac1 and Rac2 as intracellular binding partners of the H4 receptor and characterized their roles in H4 receptor signaling. We showed that histamine induced Rac GTPase activation via the H4 receptor. A Rac inhibitor NSC23766 attenuated chemotaxis of mast cells toward histamine, as well as histamine-induced calcium mobilization and extracellular signal-regulated kinase (ERK) activation. Histamine-induced migration of mast cells was also sensitive to PD98059, an inhibitor of the mitogen-activated protein kinase kinase, indicating that the Rac-ERK pathway was involved in chemotaxis through the H4 receptor. Inhibition of phosphatidylinositol-4,5-bisphosphate 3-kinase (PI3K) by LY294002 suppressed the histamine-induced chemotaxis and activation of Rac GTPases, suggesting that PI3K regulates chemotaxis upstream of Rac activation. Specific knockdown of Rac1 and Rac2 by short-hairpin RNA revealed that both Rac GTPases are necessary for histamine-induced migration. Downregulation of Rac1 and Rac2 led to attenuated response in calcium mobilization and ERK activation, respectively. These observations suggested that Rac1 and Rac2 have distinct and essential roles in intracellular signaling downstream of H4 receptor-PI3K in histamine-induced chemotaxis of mast cells.
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U2 - 10.1124/jpet.118.249706
DO - 10.1124/jpet.118.249706
M3 - Article
C2 - 30021868
AN - SCOPUS:85052908821
VL - 367
SP - 9
EP - 19
JO - The Journal of pharmacology and experimental therapeutics
JF - The Journal of pharmacology and experimental therapeutics
SN - 0022-3565
IS - 1
ER -