Role of taurine in hyperosmotic stress response of fish cells

Abstract

We identified a Na⁺- and Cl^--dependent high affinity taurine transporter as a hyperosmotic stress-inducible gene in a cultured common carp cell (EPC). Since the taurine transporter concentrates taurine from extracellular fluid to cell, upregulation of taurine transporter expression promotes the accumulation of taurine during hyperosmotic stress, suggesting the role of taurine as a compatible organic osmolyte. In tissues of tilapia (Oreochromis mossambicus), taurine transporter mRNA was also increased during high-salinity adaptation. Although increase in taurine transporter mRNA was detected in all the tissues examined, total tissue taurine content did not always increased during high-salinity adaptation. Immunohistochemistry indicated the localization of taurine transporter protein in basolateral membrane of corium and epidermal cells of pectoral fin. These results suggest that polarized transport and subsequent changes in distribution of taurine in a tissue are critical for high-salinity adaptation of an individual fish.