Regulation of taurine transport in murine macrophages

We studied the regulation of taurine transport in ANA1 murine macrophage cell line. Taurine uptake was upregulated by hypertonicity and downregulated by bacterial lypopolysaccharide (LPS) and other stimuli leading to macrophage activation. However combined stimulation with LPS plus hypertonic shock evoked an increase of taurine uptake that was even higher than with hypertonic shock alone. Taurine transport was not modified by LPS in GG2EE macrophages derived from C3H/Hej mouse strain, which harbour a mutated Toll-like receptor 4 (TLR4) and thus are not activated by LPS. The extracellular signal-regulated kinase (ERK) inhibitor PD98059 abrogates the effect of both LPS and hyperosmotic shock on ANA1 taurine uptake, while the p38 inhibitor SB203580 reduces the taurine uptake in control conditions and impairs only the response to hypertonicity. These results suggest that the effect of LPS on taurine transport depends on ERK pathway and can be influenced by environmental conditions.