Identification of two-pore domain potassium channels as potent modulators of osmotic volume regulation in human T lymphocytes

Abstract

Many functions of T lymphocytes are closely related to cell volume homeostasis and regulation, which utilize a complex network of membrane channels for anions and cations. Among the various potassium channels, the voltage-gated KV1.3 is well known to contribute greatly to the osmoregulation and particularly to the potassium release during the regulatory volume decrease (RVD) of T cells faced with hypotonic environment. Here we address a putative role of the newly identified two-pore domain (K2P) channels in the RVD of human CD4+ T lymphocytes, using a series of potent well known channel blockers. In the present study, the pharmacological profiles of RVD inhibition revealed K2P5.1 and K2P18.1 as the most important K2P channels involved in the RVD of both naïve and stimulated T cells. The impact of chemical inhibition of K2P5.1 and K2P18.1 on the RVD was comparable to that of KV1.3. K2P9.1 also notably contributed to the RVD of T cells but the extent of this contribution and its dependence on the activation status could not be unambiguously resolved. In summary, our data provide first evidence that the RVD-related potassium efflux from human T lymphocytes relies on K2P channels.