Regulation of CXCR4 Expression by Taurine in Macrophage-Like Cells

Taurine (2-aminoethanesulfonic acid) is a free β-amino acid found at high concentrations in many mammalian tissues. Taurine plays a role in several essential biological processes, including anti-oxidation, anti-inflammation, and osmoregulation. However, its regulatory mechanisms, especially at the genetic and molecular levels, have not been elucidated. Here, we targeted immune-related genes and investigated the effects of taurine on immune-related gene expression in macrophage-like cells. J774.1 cell line was used, and the effect of taurine on mRNA expression of immune-related genes such as cytokines, their receptors, and toll-like receptors was examined. Among these, taurine significantly increased the mRNA levels of C-X-C chemokine receptor 2 (CXCR2), chemokine receptor. Furthermore, we found that the taurine-induced increase in CXCR4 mRNA levels was higher than that in CXCR2 mRNA levels. Taurine increased both mRNA and protein expression levels of CXCR4. Additionally, we examined the effects of taurine analogs, including hypotaurine, β-alanine, and γ-aminobutyric acid (GABA). While GABA increased the mRNA expression of CXCR4, hypotaurine slightly increased this expression, and β-alanine had no effect, although these taurine analogs are the substrates of taurine transporter. These findings demonstrate that taurine specifically affects CXCR4 mRNA expression in macrophage-like cells.