Mono (S) hydroxy fatty acids: novel ligands for cytosolic actin

The ubiquitous hydroxylated fatty acids derived from arachidonic acid (HETEs) or linoleic acid (HODEs) exhibit diverse biological effects including chemotaxis, cell proliferation, and modulation of several enzymatic path- ways, including the 5-lipoxygenase leading to the inflamma- tory leukotrienes. It was observed that 12(S)- and 15(S)- HETE and 13(S)-HODE (12- and 15-lipoxygenase-derived metabolites, respectively) inhibited the 5-lipoxygenase present in rat basophilic leukemia (RBL -1) cell homogenates whereas the 15(R) chiral enantiomer and the nonhydroxy- lated linoleic, oleic, and stearic acids were either less potent or ineffective. In examining the mechanism of this inhibi- tion, the relative effectiveness of several fatty acids in dis- placing ( 3 H)15-HETE bound to cytosol preparations were compared and the results indicated that these (S) hydroxy fatty acids and 5(S)-HETE were significantly more potent than either the 15(R) enantiomer, 15(S)-HETE methyl ester, arachidonic acid, or prostaglandin F 2 a . In order to identify the protein(s) that specifically binds HETEs, 15(S)-HETE biotin hydrazide was used as a probe to detect any HETE- protein complexes as this compound both inhibited the 5- lipoxygenase and interfered with the binding of ( 3 H)15- HETE to cytosol preparations. SDS-PAGE analysis and chemiluminescent detection revealed that the major cytoso- lic proteins that bound this biotinylated probe had molecu- lar masses of 43 and 51 kD. Fatty acid competition experi- ments indicated that the order of effectiveness in displacing this probe from these proteins was 13(S)-HODE . 5(S)- HETE < 15(S)-HETE . . stearic acid < arachidonic acid < 15(R)-HETE. Amino acid sequence analysis showed that the 43 kD protein was actin. These findings suggest the possibility that actin may play a major role in the biological effects of monohydroxylated metabolites derived from cel- lular 5-, 12-, and 15-lipoxygenases.— Kang, L-T., and J. Y. Vanderhoek. Mono (S) hydroxy fatty acids: novel ligands for cytosolic actin. J. Lipid Res. 1998. 39: 1476-1482.