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Mizutani Y, Kihara A, Chiba H, Tojo H, Igarashi Y. 2-Hydroxy-ceramide synthesis by ceramide synthase family: enzymatic basis for the preference of FA chain length. J Lipid Res 2008; 49:2356-64. [DOI: 10.1194/jlr.m800158-jlr200] [Citation(s) in RCA: 80] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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Maldonado EN, Alderson NL, Monje PV, Wood PM, Hama H. FA2H is responsible for the formation of 2-hydroxy galactolipids in peripheral nervous system myelin. J Lipid Res 2007; 49:153-61. [PMID: 17901466 PMCID: PMC2662131 DOI: 10.1194/jlr.m700400-jlr200] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Myelin in the mammalian nervous system has a high concentration of galactolipids [galactosylceramide (GalCer) and sulfatide] with 2-hydroxy fatty acids. We recently reported that fatty acid 2-hydroxylase (FA2H), encoded by the FA2H gene, is the major fatty acid 2-hydroxylase in the mouse brain. In this report, we show that FA2H also plays a major role in the formation of 2-hydroxy galactolipids in the peripheral nervous system. FA2H mRNA and FA2H activity in the neonatal rat sciatic nerve increased rapidly during developmental myelination. The contents of 2-hydroxy fatty acids were approximately 5% of total galactolipid fatty acids at 4 days of age and increased to 60% in GalCer and to 35% in sulfatides at 60 days of age. The chain length of galactolipid fatty acids also increased significantly during myelination. FA2H expression in cultured rat Schwann cells was highly increased in response to dibutyryl cyclic AMP, which stimulates Schwann cell differentiation and upregulates myelin genes, such as UDP-galactose:ceramide galactosyltransferase and protein zero. These observations indicate that FA2H is a myelination-associated gene. FA2H-directed RNA interference (RNAi) by short-hairpin RNA expression resulted in a reduction of cellular 2-hydroxy fatty acids and 2-hydroxy GalCer in D6P2T Schwannoma cells, providing direct evidence that FA2H-dependent fatty acid 2-hydroxylation is required for the formation of 2-hydroxy galactolipids in peripheral nerve myelin. Interestingly, FA2H-directed RNAi enhanced the migration of D6P2T cells, suggesting that, in addition to their structural role in myelin, 2-hydroxy lipids may greatly influence the migratory properties of Schwann cells.
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Affiliation(s)
- Eduardo N. Maldonado
- Department of Biochemistry and Molecular Biology, Medical University of South Carolina, Charleston, South Carolina, 29425
| | - Nathan L. Alderson
- Department of Biochemistry and Molecular Biology, Medical University of South Carolina, Charleston, South Carolina, 29425
| | - Paula V. Monje
- Department of Neurological Surgery, Miami Project to Cure Paralysis, University of Miami Miller School of Medicine, FL
| | - Patrick M. Wood
- Department of Neurological Surgery, Miami Project to Cure Paralysis, University of Miami Miller School of Medicine, FL
| | - Hiroko Hama
- Department of Biochemistry and Molecular Biology, Medical University of South Carolina, Charleston, South Carolina, 29425
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Vasireddy V, Uchida Y, Salem N, Kim SY, Mandal MNA, Reddy GB, Bodepudi R, Alderson NL, Brown JC, Hama H, Dlugosz A, Elias PM, Holleran WM, Ayyagari R. Loss of functional ELOVL4 depletes very long-chain fatty acids (> or =C28) and the unique omega-O-acylceramides in skin leading to neonatal death. Hum Mol Genet 2007; 16:471-82. [PMID: 17208947 PMCID: PMC1839956 DOI: 10.1093/hmg/ddl480] [Citation(s) in RCA: 197] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Mutations in elongation of very long-chain fatty acid-4 (ELOVL4) are associated with autosomal dominant Stargardt-like macular degeneration (STGD3), with a five base-pair (5 bp) deletion mutation resulting in the loss of 51 carboxy-terminal amino acids and truncation of the protein. In addition to the retina, Elovl4 is expressed in a limited number of mammalian tissues, including skin, with unknown function(s). We generated a knock-in mouse model with the 5-bp deletion in the Elovl4 gene. As anticipated, mice carrying this mutation in the heterozygous state (Elovl4(+/del)) exhibit progressive photoreceptor degeneration. Unexpectedly, homozygous mice (Elovl4(del/del)) display scaly, wrinkled skin, have severely compromised epidermal permeability barrier function, and die within a few hours after birth. Histopathological evaluation of the Elovl4(del/del) pups revealed no apparent abnormality(ies) in vital internal organs. However, skin histology showed an abnormally-compacted outer epidermis [stratum corneum (SC)], while electron microscopy revealed deficient epidermal lamellar body contents, and lack of normal SC lamellar membranes that are essential for permeability barrier function. Lipid analyses of epidermis from Elovl4(del/del) mice revealed a global decrease in very long-chain fatty acids (VLFAs) (i.e., carbon chain > or =C28) in both the ceramide/glucosylceramide and the free fatty-acid fractions. Strikingly, Elovl4(del/del) skin was devoid of the epidermal-unique omega-O-acylceramides, that are key hydrophobic components of the extracellular lamellar membranes in mammalian SC. These findings demonstrate that ELOVL4 is required for generating VLFA critical for epidermal barrier function, and that the lack of epidermal omega-O-acylceramides is incompatible with survival in a desiccating environment.
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Affiliation(s)
- Vidyullatha Vasireddy
- Department of Ophthalmology and Visual Sciences, University of Michigan, Ann Arbor, MI- 48105
| | - Yoshikazu Uchida
- Department of Dermatology, School of Medicine, University of California San Francisco, and Veterans Administration Medical Center, San Francisco, CA-94121
| | - Norman Salem
- Laboratory of Membrane Biochemistry and Biophysics, NIAAA, National Institutes of Health, Rockville, MD-20892
| | - Soo Yeon Kim
- Laboratory of Membrane Biochemistry and Biophysics, NIAAA, National Institutes of Health, Rockville, MD-20892
| | - Md Nawajesh Ali Mandal
- Department of Ophthalmology and Visual Sciences, University of Michigan, Ann Arbor, MI- 48105
| | | | - Ravi Bodepudi
- Department of Ophthalmology and Visual Sciences, University of Michigan, Ann Arbor, MI- 48105
| | - Nathan L. Alderson
- Department of Medicine Medical University of South Carolina, Charleston, SC-29425
| | | | - Hiroko Hama
- Department of Medicine Medical University of South Carolina, Charleston, SC-29425
| | - Andrzej Dlugosz
- Department of Dermatology, University of Michigan, Ann Arbor, MI- 48105
| | - Peter M. Elias
- Department of Dermatology, School of Medicine, University of California San Francisco, and Veterans Administration Medical Center, San Francisco, CA-94121
| | - Walter M. Holleran
- Department of Dermatology, School of Medicine, University of California San Francisco, and Veterans Administration Medical Center, San Francisco, CA-94121
- Department of Pharmaceutical Chemistry, School of Pharmacy, University of California, San Francisco, CA-94143
| | - Radha Ayyagari
- Department of Ophthalmology and Visual Sciences, University of Michigan, Ann Arbor, MI- 48105
- Address for correspondence: *Radha Ayyagari, PhD., Department of Ophthalmology and Visual Sciences, W.K. Kellogg Eye Center, 1000 Wall Street, Ann Arbor, MI 48105, Phone: 734-647-6345, Fax: 734-936-7231,
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