Bioactive 4-Oxoheptanedioic Monoamide Derivatives of Proteins and Ethanolaminephospholipids: Products of Docosahexaenoate Oxidation.
Oxidative stress causes lipid-derived oxidative modification of biomolecules that has been implicated in many pathological states. Phospholipids containing polyunsaturated fatty acids are major targets of free radical-initiated oxidation. Phospholipids that incorporate docosahexaenoate (DHA) are highly enriched in important neural structures including the brain and retina, where DHA comprises 40% and 60% of total fatty acids, respectively. Oxidative fragmentation of 2-docosahexaenoyl-1-palmityl-sn-glycerophosphocholine generates esters of 4-hydroxy-7-oxohept-5-enoic acid (HOHA) and 4-keto-7-oxohept-5-enoic acid (KOHA) with 2-lysophosphatidylcholine, HOHA-PC, and KOHA-PC. Covalent HOHA adducts that incorporate the primary amino groups of proteins and ethanolamine phospholipids in carboxyethylpyrrole (CEP) derivatives were detected immunologically with anti-CEP antibodies in human tumors, retina, and blood. Now, we generated an anti-OHdiA antibody to test the hypothesis that KOHA adducts, which incorporate the primary amino groups of proteins or ethanolamine phospholipids in 4-oxo-heptanedioic (OHdiA) monoamide derivatives, are present in vivo. However, whereas the anti-CEP antibody is highly specific and does not cross-react with the OHdiA monoamide epitope, the anti-OHdiA monoamide antibody cross-reacted with CEP epitopes making it of little value as an analytical tool for OHdiA monoamides but suggesting the possibility that OHdiA monoamides would exhibit receptor-mediated biological activity similar to that of CEP. An LC-MS/MS method was developed that allows quantification of OHdiA derivatives in biological samples. We now find that KOHA-PC forms OHdiA monoamide adducts of proteins and ethanolamine phospholipids and that OHdiA-protein levels are significantly higher than OHdiA-ethanloamine phospholipid levels in blood from healthy human subjects, 0.45 μM and 0.18 μM, respectively (n = 3, and p = 0.027). OHdiA monoamide epitopes are angiogenic, causing TLR2-dependent adhesion and tube formation by human umbilical vein endothelial cells. OHdiA monoamide epitopes are only slightly less potent than CEP epitopes that contribute to the pathological angiogenesis of age-related macular degeneration and tumor growth.
Department of Chemistry, Case Western Reserve University , Cleveland, Ohio 44106, United States.
Junhong
J
Guo
Department of Chemistry, Case Western Reserve University , Cleveland, Ohio 44106, United States.
Li
L
Hong
Department of Molecular Cardiology, Cleveland Clinic , Cleveland, Ohio 44195, United States.
Xiaoxia Z
XZ
West
Department of Chemistry, Case Western Reserve University , Cleveland, Ohio 44106, United States.
Hua
H
Wang
Department of Chemistry, Case Western Reserve University , Cleveland, Ohio 44106, United States.
Robert G
RG
Salomon
D000818:Animals; D002417:Cattle; D003998:Dicarboxylic Acids / Q000737:chemistry / Q000378:metabolism*; D004281:Docosahexaenoic Acids / Q000737:chemistry / Q000378:metabolism*; D019856:Ethanolamine / Q000097:blood / Q000737:chemistry / Q000378:metabolism*; D006538:Heptanoic Acids / Q000737:chemistry / Q000378:metabolism*; D061307:Human Umbilical Vein Endothelial Cells / Q000166:cytology / Q000378:metabolism; D006801:Humans; D015394:Molecular Structure; D010084:Oxidation-Reduction; D010743:Phospholipids / Q000097:blood / Q000737:chemistry / Q000378:metabolism*; D012709:Serum Albumin / Q000737:chemistry / Q000378:metabolism*
D003998:Dicarboxylic Acids; D006538:Heptanoic Acids; D010743:Phospholipids; D012709:Serum Albumin; D004281:Docosahexaenoic Acids; D019856:Ethanolamine