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OxLDL antibody inhibits MCP-1 release in monocytes/macrophages by regulating Ca2+ /K+ channel flow.

ABSTRACT: oxLDL peptide vaccine and its antibody adoptive transferring have shown a significantly preventive or therapeutic effect in atherosclerotic animal model. The molecular mechanism behind this is obscure. Here, we report that oxLDL induces MCP-1 release in monocytes/macrophages through their TLR-4 (Toll-like receptor 4) and ERK MAPK pathway and is calcium/potassium channel-dependent. Using blocking antibodies against CD36, TLR-4, SR-AI and LOX-1, only TLR-4 antibody was found to have an inhibitory effect and ERK MAPK-specific inhibitor (PD98059) was found to have a dramatic inhibitory effect compared to inhibitors of other MAPK group members (p38 and JNK MAPKs) on oxLDL-induced MCP-1 release. The release of cytokines and chemokines needs influx of extracellular calcium and imbalance of efflux of potassium. Nifedipine, a voltage-dependent calcium channel (VDCC) inhibitor, and glyburide, an ATP-regulated potassium channel (K+ATP ) inhibitor, inhibit oxLDL-induced MCP-1 release. Potassium efflux and influx counterbalance maintains the negative potential of macrophages to open calcium channels, and our results suggest that oxLDL actually induces the closing of potassium influx channel - inward rectifier channel (Kir ) and ensuing the opening of calcium channel. ERK MAPK inhibitor PD98059 inhibits oxLDL-induced Ca2+ /Kir channel alterations. The interfering of oxLDL-induced MCP-1 release by its monoclonal antibody is through its Fc?RIIB (CD32). Using blocking antibodies against Fc?RI (CD64), Fc?RIIB (CD32) and Fc?RIII (CD16), only CD32 blocking antibody was found to reverse the inhibitory effect of oxLDL antibody on oxLDL-induced MCP-1 release. Interestingly, oxLDL antibody specifically inhibits oxLDL-induced ERK MAPK activation and ensuing Ca2+ /Kir channel alterations, and MCP-1 release. Thus, we found a molecular mechanism of oxLDL antibody on inhibition of oxLDL-induced ERK MAPK pathway and consequent MCP-1 release.

SUBMITTER: Su J

PROVIDER: S-EPMC5387129 | biostudies-literature | 2017 May

REPOSITORIES: biostudies-literature

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oxLDL antibody inhibits MCP-1 release in monocytes/macrophages by regulating Ca<sup>2+</sup> /K<sup>+</sup> channel flow.

Su Jinyu J Zhou Hui H Liu Xianyan X Nilsson Jan J Fredrikson Gunilla Nordin GN Zhao Ming M

Journal of cellular and molecular medicine 20161220 5

oxLDL peptide vaccine and its antibody adoptive transferring have shown a significantly preventive or therapeutic effect in atherosclerotic animal model. The molecular mechanism behind this is obscure. Here, we report that oxLDL induces MCP-1 release in monocytes/macrophages through their TLR-4 (Toll-like receptor 4) and ERK MAPK pathway and is calcium/potassium channel-dependent. Using blocking antibodies against CD36, TLR-4, SR-AI and LOX-1, only TLR-4 antibody was found to have an inhibitory ...[more]

PMID: 27995732

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Project description:Orai1, the pore subunit of Ca(2+) release-activated Ca(2+) channels, has four transmembrane segments (TMs). The first segment, TMI, lines the pore and plays an important role in channel activation and ion permeation. TMIII, on the other hand, does not line the pore but still regulates channel gating and permeation properties. To understand the role of TMIII, we have mutated and characterized several residues in this domain. Mutation of Trp-176 to Cys (W176C) and Gly-183 to Ala (G183A) had dramatic effects. Unlike wild-type channels, which exhibit little outward current and are activated by STIM1, W176C mutant channels exhibited a large outward current at positive potentials and were constitutively active in the absence of STIM1. G183A mutant channels also exhibited substantial outward currents but were active only in the presence of 2-aminoethoxydiphenyl borate (2-APB), irrespective of STIM1. With W176C mutant channels inward, monovalent currents were blocked by Ca(2+) with a high affinity similar to the wild type, but the Ca(2+)-dependent blocking of outward currents differed in the two cases. Although a 50% block of the WT outward current required 250 μm Ca(2+), more than 6 mm was necessary to have the same effect on W176C mutant channels. In the presence of extracellular Ca(2+), W176C and G183A outward currents developed slowly in a voltage-dependent manner, whereas they developed almost instantaneously in the absence of Ca(2+). These changes in permeation and gating properties mimic the changes induced by mutations of Glu-190 in TMIII and Asp-110/Asp-112 in the TMI/TMII loop. On the basis of these data, we propose that TMIII maintains negatively charged residues at or near the selectivity filter in a conformation that facilitates Ca(2+) inward currents and prevents outward currents of monovalent cations. In addition, to controlling selectivity, TMIII may also stabilize channel gating in a closed state in the absence of STIM1 in a Trp-176-dependent manner.

Dataset Information

OxLDL antibody inhibits MCP-1 release in monocytes/macrophages by regulating Ca2+ /K+ channel flow.

Publications

oxLDL antibody inhibits MCP-1 release in monocytes/macrophages by regulating Ca<sup>2+</sup> /K<sup>+</sup> channel flow.

Similar Datasets

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