AIM:To compare the synthesis efficiency of n3 and n6 very long chain polyunsaturated fatty acid(VLC-PUFA)by overexpressing ELOVL4 protein, providing guidance for treating Stargardt-like macular dystrophy(STGD3).

METHODS:To establish recombinant adenovirus with the ELOVL4 protein and green fluorescent protein, transferred into cultured PC12 cells. The cells were divided into 3 groups: PC12, PC12+Ad-GFP and PC12+Ad- ELOVL4, former two groups serve as controls. ELOVL4 gene expression was quantified by qRT-PCRs. ELOVL4 protein was analyzed by Western-Blot(WB). The transduced cells were treated with both EPA and AA(1:1). After 48h of incubation, cells were collected, total lipids extracted and fatty acid methyl esters prepared and analyzed by gas chromatography-mass spectrometry(GC-MS).

RESULTS: When supplemented together, 20:5n3(EPA)and 20:4n6(AA)were efficiently taken up at almost the same amounts in the PC12 cells regardless of ELOVL4 expression. The ELOVL4-expressing cells elongated both EPA and AA to a series of n3 and n6 VLC-PUFAs. From 20:5n3/EPA, 34:5n3 and 36:5n3 account for 0.71% and 1.6%, respectively. From 20:4n6/DHA, 34:4n6 and 36:4n6 were only 0.46% and 0.61%, respectively. The total relative mol% of n3 VLC-PUFAs synthesized from EPA was almost two times that of n6 VLC-PUFAs synthesized from AA.

CONCLUSION: ELOVL4 protein preferentially elongates n3 PUFA to VLC-PUFAs over n6 PUFA. Dietary supplementation of appropriate n3/n6 PUFAs may provide STGD3 patients with some therapeutic benefits.