High amphipathicity of α-helical peptides enhances unmethylated CpG DNA-induced activation of mouse macrophage-like RAW264.7 cells

TL;DR

A study shows that α-helical peptides with high amphipathicity boost CpG DNA-induced activation in mouse macrophage-like cells.

Contribution

The study identifies high amphipathicity as a key factor in enhancing CpG DNA-induced activation by α-helical peptides.

Findings

Kn2-7's high amphipathicity enhances CpG DNA-induced activation in RAW264.7 cells.

L5 derivatives with increased amphipathicity also enhance CpG DNA-induced activation.

Amphipathicity does not affect DNA uptake but is crucial for activation enhancement.

Abstract

The α-helical antimicrobial peptide Kn2-7 enhances the activation of mouse macrophage-like RAW264.7 induced by DNA containing unmethylated cytosine-guanine motifs (CpG DNA). This enhancement is related to increased cellular uptake of DNA by Kn2-7, but the relevant properties of Kn2-7 are unknown. Physicochemical property analysis revealed that Kn2-7 has high amphipathicity. In contrast, the α-helical antimicrobial peptide L5, which increases the cellular uptake of CpG DNA but does not enhance CpG DNA-induced activation, has low amphipathicity. Kn2-7 derivatives with decreased amphipathicity but the same amino acid composition as Kn2-7 did not enhance CpG DNA-induced activation. On the other hand, L5 derivatives with high amphipathicity but the same amino acid composition as L5 enhanced CpG DNA-induced activation. Cellular uptake of DNA was not increased by the L5 derivatives, indicating that high amphipathicity does not affect DNA uptake. Furthermore, α-helical peptides with reversed sequences relative to the Kn2-7 and L5 derivatives with high amphipathicity were synthesized. The reversed-sequence peptides, which had the same amphipathicity but different amino acid sequences from their counterparts, enhanced CpG DNA-induced activation. Taken together, these observations indicate that the high amphipathicity of α-helical peptides enhances the CpG DNA-induced activation of RAW264.7.

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