Ionomycin Restores Taurine Transporter Activity in Cyclosporin-A Treated Macrophages

Abstract

Do 449-900, KoreaTaurine is accumulated at high concentrations in various tissues. The taurine transporter (TAUT) is responsible for the transportation of taurine in the cell. The transporter is affected by various stimuli to maintain cell volume. Macrophage cell volume varies in its activated states. In our experiment, it was found that the murine macrophage cell line, RAW264.7, expressed TAUT protein in its membrane. Its transporting activities could be blocked by -amino acid such as -alanine, but not by a-amino acids in this cell line. when assessed in RAW264.7 cells under the influence of immunosuppressive reagents, the activity of the TAUT was decreased by treatment with rapamycin (RM) or cyclosporin A (CSA). However, when ionomycin (IM) was added to this system, TAUT activity was recovered only in CSA-treated cells, in a concentrationdependent manner. in order to inhibit voltage gated Ca 2 + channels, calmidazolium was added to the RAW264.7 cell line. Treatment of the cells with calmidazolium completely blocked TAUT. Furthermore, addition of IM to this system resulted in recovery the activity of TAUT again. When we added phorbol myristyl acetate (PMA) to the cell line, secretion of nitric oxide (NO) was increased 4-fold and the TAUT activity was decreased 5-fold. However, the addition of N-nitro L-arginine methyl ester (L-NAME), an inducible NO synthase (iNOS) inhibitor, to the PMA-treated cells induced recovery of TAUT activity. These results showed that the activity of TAUT was sensitive to both the intracellular concentrations of Ca 2+ and NO.

Ethane-β-Sultam Modifies the Activation of the Innate Immune System Induced by Intermittent Ethanol Administration in Female Adolescent Rats

“…Since TauT activity is decreased by inflammation [26][27][28], this might indicate that the ability of such cells to protect themselves from inflammation will be decreased. Therefore taurine analogues which are able to traverse cellular membranes independently of TauT may enhance intracellular taurine levels and promote anti-inflammatory pathways Beta sultam is an analogue of β-lactams, a group of compounds which are able to inactivate serine enzymes, i,e, elastase, which is released in response to inflammatory stimuli and plays a major role in protein digestion following phagocytosis [29].…”

Anti-inflammatory actions of a taurine analogue, ethane β-sultam, in phagocytic cells, in vivo and in vitro

“…TauT controls the influx of taurine within very narrow limits, such that exogenously administered taurine only transiently increases levels within a number of cellular types, including liver [6] and, to a lesser extent, brain [7] [8] [6]. TauT activity can be modified by a number of factors including inflammation, where it is decreased [9] [10] [11], calcium ions and nitric oxide [9], glucocorticoids [12], protein kinase C activation in rat astroglial cells 4 [13] and human glioma GL15 cells [14]. Therefore taurine analogues, which are able to traverse membranes independently of TauT, may enhance intracellular taurine levels thereby promoting anti-inflammatory pathways.…”