title: Loss of functional ELOVL4 depletes very long-chain fatty acids (> or =C28) and the unique omega-O-acylceramides in skin leading to neonatal death.
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.
authors.affiliation: Department of Ophthalmology and Visual Sciences, University of Michigan, Ann Arbor, MI 48105, USA.
authors.forename: Vidyullatha
authors.initials: V
authors.lastname: Vasireddy
authors.forename: Yoshikazu
authors.initials: Y
authors.lastname: Uchida
authors.forename: Norman
authors.initials: N
authors.lastname: Salem
authors.forename: Soo Yeon
authors.initials: SY
authors.lastname: Kim
authors.forename: Md Nawajesh Ali
authors.initials: MN
authors.lastname: Mandal
authors.forename: Geereddy Bhanuprakash
authors.initials: GB
authors.lastname: Reddy
authors.forename: Ravi
authors.initials: R
authors.lastname: Bodepudi
authors.forename: Nathan L
authors.initials: NL
authors.lastname: Alderson
authors.forename: Johnie C
authors.initials: JC
authors.lastname: Brown
authors.forename: Hiroko
authors.initials: H
authors.lastname: Hama
authors.forename: Andrzej
authors.initials: A
authors.lastname: Dlugosz
authors.forename: Peter M
authors.initials: PM
authors.lastname: Elias
authors.forename: Walter M
authors.initials: WM
authors.lastname: Holleran
authors.forename: Radha
authors.initials: R
authors.lastname: Ayyagari
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D020029:Base Pairing; D015415:Biomarkers; D002454:Cell Differentiation; D002518:Ceramides / Q000172:deficiency*; D002853:Chromatography, Liquid; D004817:Epidermis / Q000737:chemistry / Q000473:pathology / Q000648:ultrastructure; D005136:Eye Proteins / Q000235:genetics / Q000378:metabolism*; D005227:Fatty Acids / Q000378:metabolism*; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation; D013058:Mass Spectrometry; D008565:Membrane Proteins / Q000172:deficiency* / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D010641:Phenotype; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D017384:Sequence Deletion; D012867:Skin / Q000378:metabolism* / Q000473:pathology; D012868:Skin Abnormalities / Q000401:mortality* / Q000473:pathology*
chemical_list: D015415:Biomarkers; D002518:Ceramides; C498834:Elovl4 protein, mouse; D005136:Eye Proteins; D005227:Fatty Acids; D008565:Membrane Proteins; D012333:RNA, Messenger