N-palmitoylation of the radioprotective domain of interleukin-1 affords inhibition of LPS-induced nitric oxide generation.
Interleukin-1beta (IL-1beta), a cytokine involved in homeostatic processes such as the immune system and inflammatory reactions, is a potent inducer of nitric oxide. The nonapeptide of human IL-1beta (VQGEESNDK, position 163-171, specific radioprotective domain--SRD) has been shown to retain radioprotective, immunostimulatory, and adjuvant activities of the native molecule without any inflammatory and pyrogenic properties. Unlike the parent IL-1, SRD did not induce nitric oxide (NO) in control or irradiated RAW 264.7 cells nor did it affect inducible nitric oxide synthase (iNOS) as shown by ELISA based mRNA assay (Quantikine). A lipophillic derivative of the SRD (a palmitoyl residue at the amino terminus of the SRD) was synthesized (palmitoyl specific radioprotective domain, P-SRD) to find out if this structural derivatization would restore the NO-inducing ability of IL-1. Surprisingly, P-SRD not only did not induce NO, but significantly inhibited lipopolysaccharide (LPS) stimulated nitric oxide (NO) production. Quantikine studies indicated that P-SRD also inhibited iNOS in LPS stimulated macrophage cells, suggesting that decrease in NO production in the presence of P-SRD was the result of iNOS mRNA inhibition. These results indicate that N-palmitoylation of SRD may effectively ameliorate potentially fatal symptoms of LPS-induced endotoxemic hypotensive shock associated with IL-1 without inflammatory and pyrogenic toxic side effects.
Singh
V K
VK
Radiation Casualty Management Team, Radiation Medicine Department, Armed Forces Radiobiology Research Institute, Bethesda, Maryland 20889-5603, USA. singh@afrri.usuhs.mil
Seed
T M
TM
Kumar
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KS
D000595:Amino Acid Sequence; D000818:Animals; D002460:Cell Line; D006801:Humans; D007375:Interleukin-1 / Q000737:chemistry* / Q000494:pharmacology*; D008070:Lipopolysaccharides / Q000633:toxicity; D008264:Macrophages / Q000187:drug effects / Q000378:metabolism / Q000528:radiation effects; D051379:Mice; D009569:Nitric Oxide / Q000096:biosynthesis*; D019001:Nitric Oxide Synthase / Q000235:genetics; D052247:Nitric Oxide Synthase Type II; D019308:Palmitic Acid / Q000737:chemistry; D010446:Peptide Fragments / Q000737:chemistry* / Q000494:pharmacology*; D017434:Protein Structure, Tertiary; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D011837:Radiation-Protective Agents / Q000737:chemistry / Q000494:pharmacology; D011994:Recombinant Proteins / Q000737:chemistry / Q000494:pharmacology; D012772:Shock, Septic / Q000209:etiology / Q000517:prevention & control
D007375:Interleukin-1; D008070:Lipopolysaccharides; D010446:Peptide Fragments; D012333:RNA, Messenger; D011837:Radiation-Protective Agents; D011994:Recombinant Proteins; D019308:Palmitic Acid; D009569:Nitric Oxide; C496319:NOS2 protein, human; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II; C496317:Nos2 protein, mouse