Examination of VLC-PUFA-deficient photoreceptor terminals

Lea D. Bennett, Blake R. Hopiavuori, Richard S. Brush, Michael Chan, Matthew J. Van Hook, Wallace B. Thoreson, Robert E. Anderson

Research output: Contribution to journalArticle

15 Scopus citations

Abstract

Purpose. Juvenile-onset autosomal dominant Stargardt-like macular dystrophy (STGD3) is caused by mutations in ELOVL4 (elongation of very long fatty acids-4), an elongase necessary for the biosynthesis of very long chain fatty acids (VLC-FAs ≥ C26). Photoreceptors are enriched with VLC polyunsaturated fatty acids (VLC-PUFAs), which are necessary for long-term survival of rod photoreceptors. The purpose of these studies was to determine the effect of deletion of VLC-PUFAs on rod synaptic function in retinas of mice conditionally depleted (KO) of Elovl4. Methods. Retina function was assessed in wild-type (WT) and KO by electroretinography. Outer plexiform structure was evaluated by immunofluorescence and transmission electron microscopy. Single-cell recordings measured rod ion channel operation and rod bipolar glutamate signaling. Sucrose gradient centrifugation was used to isolate synaptosomes from bovine retina. Proteins and lipids were analyzed by Western blotting and tandem mass spectroscopy, respectively. Results. Inner retinal responses (b-wave, oscillatory potentials, and scotopic threshold responses) of the ERG were decreased in the KO mice compared to controls. However the rod ion channel operation and bipolar glutamate responses were comparable between groups. Biochemical analysis revealed that conventional and ribbon synapses have VLC-PUFAs. Ultrastructural analysis showed that the outer plexiform layer was disorganized and the diameter of vesicles in rod terminals was smaller in the KO mice. Conclusions. Very long chain PUFAs affect rod function by contributing to synaptic vesicle size, which may alter the dynamics of synaptic transmission, ultimately resulting in a loss of neuronal connectivity and death of rod photoreceptors.

Original languageEnglish (US)
Pages (from-to)4063-4072
Number of pages10
JournalInvestigative Ophthalmology and Visual Science
Volume55
Issue number7
DOIs
StatePublished - Apr 24 2014

Keywords

  • ELOVL4
  • STDG3
  • VLC-PUFA

ASJC Scopus subject areas

  • Ophthalmology
  • Sensory Systems
  • Cellular and Molecular Neuroscience

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