Figure 8.

Fatty acid selectivity of sPLA₂-V. Lipids extracted from the spleen of 1-year-old sPLA₂-V-deficient (−/−) and littermate control (+/+) mice were subjected to mass spectrometric lipidomics analysis (values are mean ± SEM, *P < 0.05 and **P < 0.01). Experiments were performed in accordance with the procedure described previously (5). Y-axis indicate relative abundance (AUC; area under the curve) of each product per mg tissue. Free fatty acid (FFA) species with a lower degree of unsaturation, including PA (16:0), palmitoleic acid (16:1), stearic acid (18:0; SA), OA (18:1), LA (18:2), eicosanoic acid (20:0) and eicosenoic acid (C20:1), but not PUFAs including AA (20:4), EPA (20:5), DPA (22:5) and DHA (22:6), were significantly reduced in sPLA₂-V-deficient mice relative to control mice. Accordingly, LA metabolites, including 9- and 13-hydroxyoctadecadienoic acids (HODEs) among others, were substantially decreased in mutant mice relative to control mice, whereas none of the AA, EPA and DHA metabolites differed significantly between the genotypes. These results are consistent with the view that sPLA₂-V has a propensity to preferentially hydrolyze phospholipids having sn-2 fatty acids with a lower degree of unsaturation, as illustrated at right bottom.