title: In vivo effect of mutant ELOVL4 on the expression and function of wild-type ELOVL4.
abstract: OBJECTIVE
  Mutations in the elongation of very long chain fatty acids 4 (ELOVL4) gene cause human Stargardt's macular dystrophy 3 (STGD3), a juvenile onset dominant form of macular degeneration. To understand the role of the ELOVL4 protein in retinal function, several mouse models have been developed by using transgenic (TG), knock-in (Elovl4(+/mut)), and knockout (Elovl4(+/-)) approaches. Here we analyzed quantitatively the ELOVL4 protein and its enzymatic products (very long chain saturated fatty acid [VLC-FA] and VLC-polyunsaturated fatty acid [VLC-PUFA]) in the retinas of 8 to 10-week-old TG1(+), TG2(+), and Elovl4(+/mut) mice that harbor the mutant ELOVL4 and compared them to their wild-type littermates and Elovl4(+/-) that do not express the mutant protein. We also analyzed skin from these mice to gain insight into the pathogenesis resulting from the ELOVL4 mutation.
  
  
  METHODS
  ELOVL4 protein localization in the retina was determined by immunohistochemistry. Levels of wild-type ELOVL4 protein in skin and retinas were determined by Western blotting. Total lipids from skin and retinas were measured by gas chromatography-mass spectrometry (GC-MS). Retinal glycerophosphatidylcholines (PC) were analyzed by tandem mass spectrometry.
  
  
  RESULTS
  Immunohistochemical and Western analysis indicated that wild-type ELOVL4 protein was reduced in heterozygous Elovl4(+/mut) and Elovl4(+/-) retinas, but not in TG2(+) retinas. We found that VLC-FA was reduced by 50% in the skin of Elovl4(+/-) and by 60% to 65% in Elovl4(+/mut). We found VLC-PUFA levels at ∼ 50% in both the retinas, and wild-type levels of VLC-PUFA in TG2(+) retinas.
  
  
  CONCLUSIONS
  We conclude that the presence of the mutant ELOVL4 does not affect the function of wild-type ELOVL4 in the fully developed 8- to 10-week-old retinas.
authors.affiliation: Department of Ophthalmology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, United States.
authors.forename: Nawajes A
authors.initials: NA
authors.lastname: Mandal
authors.forename: Julie-Thu A
authors.initials: JT
authors.lastname: Tran
authors.forename: Lixin
authors.initials: L
authors.lastname: Zheng
authors.forename: Joseph L
authors.initials: JL
authors.lastname: Wilkerson
authors.forename: Richard S
authors.initials: RS
authors.lastname: Brush
authors.forename: Joel
authors.initials: J
authors.lastname: McRae
authors.forename: Martin-Paul
authors.initials: MP
authors.lastname: Agbaga
authors.forename: Kang
authors.initials: K
authors.lastname: Zhang
authors.forename: Konstantin
authors.initials: K
authors.lastname: Petrukhin
authors.forename: Radha
authors.initials: R
authors.lastname: Ayyagari
authors.forename: Robert E
authors.initials: RE
authors.lastname: Anderson
mesh_terms: D000818:Animals; D015153:Blotting, Western; D004247:DNA / Q000235:genetics*; D004195:Disease Models, Animal; D005136:Eye Proteins / Q000096:biosynthesis / Q000235:genetics*; D008401:Gas Chromatography-Mass Spectrometry; D005786:Gene Expression Regulation; D005838:Genotype; D006801:Humans; D007150:Immunohistochemistry; D008565:Membrane Proteins / Q000096:biosynthesis / Q000235:genetics*; D051379:Mice; D008810:Mice, Inbred C57BL; D012160:Retina / Q000378:metabolism* / Q000473:pathology; D012162:Retinal Degeneration / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D053719:Tandem Mass Spectrometry
chemical_list: C498834:Elovl4 protein, mouse; D005136:Eye Proteins; D008565:Membrane Proteins; D004247:DNA
keywords: ELOVL4; VLC-PUFA; retina