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The Interaction of the LL‐37 Peptide with CpG DNA Oligonucleotides
Author(s) -
Avelsgard Irmamarie,
Craig Maria
Publication year - 2015
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.29.1_supplement.571.24
Subject(s) - dna , electrophoretic mobility shift assay , oligonucleotide , microbiology and biotechnology , chemistry , cpg site , cathelicidin , innate immune system , biology , biochemistry , gene , transcription factor , gene expression , receptor , dna methylation
LL‐37, a member of the cathelicidin family of innate immune peptides, forms complexes with extracellular self‐DNA and aids in the transport of DNA across cell membranes. LL‐37/DNA complex formation and DNA internalization by immune cells activates a series of events that lead to an autoimmune response. We have used electrophoretic mobility shift assays (EMSA) and western blotting to examine the details of complex formation between LL‐37 and 24‐bp DNA fragments containing CpG sequences. We observe by EMSA that increasing amounts of CpG DNA are shifted as the concentration of LL‐37 increases. Quantitative analysis of DNA bands in the EMSA gels has allowed us to construct binding curves for the formation of LL‐37/DNA complexes. The curves indicate that a strong cooperative effect in the binding process leads to tight binding with low apparent dissociation constants for CpG DNA above an LL‐37 concentration of about 20 µM. Complementary experiments in a THP‐1 monocytic cell model investigate the uptake of LL‐37 and LL‐37/DNA complexes.