We aimed to study the involvement of Kir3.1 channel in TLR4-mediated signaling. LPS stimulation induced the recruitment of TLR4 and Kir3.1 into the lipid raft in THP-1 cells. Treatment with Tertiapin-Q an inhibitor of Kir3.1, markedly abolished the recruitment of TLR4 into the lipid raft and inhibited the LPS-induced NF-kappa B activation, resulting in decreased production of TNF-alpha, IL-1 beta, and IL-6. To verify the specific role of the Kir3.1 channel, we generated Kir3.1-knockdown THP-1 cells. The Kir3.1(KD) THP-1 cells exhibited inhibition of NF-kappa B activation and production of these pro-inflammatory cytokines in response to TLR4 stimulation. Taken together, our results demonstrate that the Kir3.1 channel is involved in the TLR4-mediated signal at an early event by facilitating the recruitment of TLR4 into lipid raft. (C) 2011 Elsevier Inc. All rights reserved.