ELOVL4 Mutations That Cause Spinocerebellar Ataxia-34 Differentially Alter Very Long Chain Fatty Acid Biosynthesis

Yeboah Kofi Gyening, Neeraj Kumar Chauhan, Madison Tytanic, Vicki Ea, Richard S. Brush, Martin Paul Agbaga

Research output: Contribution to journalArticlepeer-review

8 Scopus citations

Abstract

The FA Elongase-4 (ELOVL4) enzyme mediates biosynthesis of both very long chain (VLC)PUFAs and VLC-saturated FA (VLC-SFAs). VLC-PUFAs play critical roles in retina and sperm function, whereas VLC-SFAs are predominantly associated with brain function and maintenance of the skin permeability barrier. While some ELOVL4 mutations cause Autosomal Dominant Stargardt-like Macular Dystrophy (STGD3), other ELOVL4 point mutations, such as L168F and W246G, affect the brain and/or skin, leading to Spinocerebellar Ataxia-34 (SCA34) and Erythrokeratodermia variabilis. The mechanisms by which these ELOVL4 mutations alter VLC-PUFA and VLC-SFA biosynthesis to cause the different tissue-specific pathologies are not well understood. To understand how these mutations alter VLC-PUFA and VLC-SFA biosynthesis, we expressed WT-ELOVL4, L168F, and W246G ELOVL4 variants in cell culture and supplemented the cultures with VLC-PUFA or VLC-SFA precursors. Total lipids were extracted, converted to FA methyl esters, and quantified by gas chromatography. We showed that L168F and W246G mutants were capable of VLC-PUFA biosynthesis. W246G synthesized and accumulated 32:6n3, while L168F exhibited gain of function in VLC-PUFA biosynthesis as it made 38:5n3, which we did not detect in WT-ELOVL4 or W246G-expressing cells. However, compared with WT-ELOVL4, both L168F and W246G mutants were deficient in VLC-SFA biosynthesis, especially the W246G protein, which showed negligible VLC-SFA biosynthesis. These results suggest VLC-PUFA biosynthetic capabilities of L168F and W246G in the retina, which may explain the lack of retinal phenotype in SCA34. Defects in VLC-SFA biosynthesis by these variants may be a contributing factor to the pathogenic mechanism of SCA34 and Erythrokeratodermia variabilis.

Original languageEnglish
Article number100317
JournalJournal of Lipid Research
Volume64
Issue number1
DOIs
StatePublished - Jan 2023

Keywords

  • autosomal dominant Stargardt macular dystrophy
  • elongation of very long chain fatty acid-4
  • erythrokeratodermia variabilis
  • eye/retina
  • fatty acid metabolism
  • lipids
  • omega-3 fatty acids
  • saturated fatty acid
  • tissue-specific pathologies
  • very long chain polyunsaturated fatty acids

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