FA2H-dependent fatty acid 2-hydroxylation in postnatal mouse brain.
2-Hydroxy fatty acids are relatively minor species of membrane lipids found almost exclusively as N-acyl chains of sphingolipids. In mammals, 2-hydroxy sphingolipids are uniquely abundant in myelin galactosylceramide and sulfatide. Despite the well-documented abundance of 2-hydroxy galactolipids in the nervous system, the enzymatic process of the 2-hydroxylation is not fully understood. To fill this gap, we have identified a human fatty acid 2-hydroxylase gene (FA2H) that is highly expressed in brain. In this report, we test the hypothesis that FA2H is the major fatty acid 2-hydroxylase in mouse brain and that free 2-hydroxy fatty acids are formed as precursors of myelin 2-hydroxy galactolipids. The fatty acid compositions of galactolipids in neonatal mouse brain gradually changed during the course of myelination. The relative ratio of 2-hydroxy versus nonhydroxy galactolipids was very low at 2 days of age ( approximately 8% of total galactolipids) and increased 6- to 8-fold by 30 days of age. During this period, free 2-hydroxy fatty acid levels in mouse brain increased 5- to 9-fold, and their composition was reflected in the fatty acids in galactolipids, consistent with a precursor-product relationship. The changes in free 2-hydroxy fatty acid levels coincided with fatty acid 2-hydroxylase activity and with the upregulation of FA2H expression. Furthermore, mouse brain fatty acid 2-hydroxylase activity was inhibited by anti-FA2H antibodies. Together, these data provide evidence that FA2H is the major fatty acid 2-hydroxylase in brain and that 2-hydroxylation of free fatty acids is the first step in the synthesis of 2-hydroxy galactolipids.
Alderson
Nathan L
NL
Department of Biochemistry and Molecular Biology, Medical University of South Carolina, Charleston, SC 29425, USA.
Maldonado
Eduardo N
EN
Kern
Michael J
MJ
Bhat
Narayan R
NR
Hama
Hiroko
H
D000595:Amino Acid Sequence; D000818:Animals; D000831:Animals, Newborn; D001483:Base Sequence; D001921:Brain / Q000378:metabolism*; D002478:Cells, Cultured; D017931:DNA Primers / Q000235:genetics; D005227:Fatty Acids / Q000737:chemistry / Q000378:metabolism*; D038983:Galactolipids / Q000096:biosynthesis; D006801:Humans; D006900:Hydroxylation; D051379:Mice; D008810:Mice, Inbred C57BL; D006899:Mixed Function Oxygenases / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism
D017931:DNA Primers; D005227:Fatty Acids; D038983:Galactolipids; D012333:RNA, Messenger; D006899:Mixed Function Oxygenases; C019081:fatty acid alpha-hydroxylase