PKC regulation of the human equilibrative nucleoside transporter, hENT1

Abstract

Regulation of nucleoside transporters is poorly understood. We show that acute stimulation of protein kinase C (PKC) causes a rapid increase in S‐(4‐nitrobenzyl)‐6‐thioinosine‐sensitive (human equilibrative nucleoside transporter 1, hENT1) nucleoside uptake, in human cultured cells, which is not due to increased metabolism and which can be blocked by PKC inhibitors. Use of isoform‐specific inhibitors indicates that PKC δ and/or ϵ (but not α, β or γ) are responsible for the acute effects. Down‐regulation of PKC decreases hENT1‐dependent uridine uptake. These are the first data to show rapid PKC δ/ϵ‐dependent stimulation of hENT1 transport by a mechanism that may involve activation of transporters at the membrane possibly by post‐translational modification of the protein.