Sphingosine 1-phosphate receptor type 2 positively regulates interleukin (IL)-4/IL-13-induced STAT6 phosphorylation

Previous reports have demonstrated that sphingosine 1-phosphate receptor type 2 (S1P(2)) is involved in the activation of signal transducer and activator of transcription (STAT) 6. Additionally, the major signaling pathway of S1P(2) is the Rho-Rho kinase pathway. In this study, we examined the role of S1P(2) in STAT6 activation in a macrophage (M phi) model using THP-1 cells differentiated with phorbol 12-myristate 13-acetate (PMA). We established S1P(2)(knockout) THP-1 cells using the CRISPR-Cas9 gene editing system. The PMA-treated S1P(2)(knockout) THP-1 M phi s showed decreases in IL-4/IL-13-induced phosphorylation of Janus-activated kinase (JAK) 1, JAK2, and STAT6 as well as mRNA expression of the M2 marker ARG1 compared with wild-type THP-1 M phi s. Pretreatment of PMA-treated THP-1 M phi s with the S1P(2) antagonist JTE-013, the Rho inhibitor Rhosin or the Rho kinase inhibitor Y27632 inhibited the IL-4/IL-13-induced increase in STAT6 phosphorylation. The expressions of suppressor of cytokine signaling 3 in the S1P(2)(knockout) THP-1 M phi s were higher than those in wild-type THP-1 M phi s. In addition, the protein tyrosine phosphatase inhibitor vanadate enhanced IL-4-induced STAT6 phosphorylation in the S1P(2)(knockout) THP-1 M phi s, suggesting that S1P(2)-Rho-Rho kinase inhibited the negative regulation of STAT6. These results suggest that the S1P(2)-Rho-Rho kinase pathway is necessary for full activation of STAT6 by IL-4/IL13 in M phi s.