The role of defensin fragment in the regulation of fatty acid composition of membrane phospholipids in epithelial-like cells

It is shown that a tetrapeptide fragment of defensin does not alter the phospholipid composition in the membranes of CHO-K1 cells but regulates the fatty acid composition of phosphatidylcholine, phosphatidylethanolamine (PEA), phosphatidylserine (PS), and phosphatidylinositol (PI). Incubation of the cells in the presence of this tetrapeptide resulted in modification of unsaturated fatty acid composition in the studied phospholipids. The content of monoenoic (mainly C18 : 1ω9) and/or dienoic (C18 : 2ω6) fatty acids increased, while the level of polyenoic fatty acids decreased. It was found that in the polyenoic fatty acid group of the PEA, PS and PI molecules, the ω3-/ω6-acid ratio decreased mainly due to the lower content of long-chain ω3-acids with 20 and/or 22 carbonic atoms. The possible role of this peptide in inhibition of the activity of Δ6- and Δ5-desaturases involved in the synthesis of long-chain polyenoic fatty acids, the quantitative alteration of which in phospholipids influences physicochemical parameters in cell membranes, is discussed.