Functional Characterization Of The Promoter Region Of The Zebrafish Elovl Family Member 5
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Date
2015-10
Authors
YEN SHAN, CHEW
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Abstract
Elongation of very long-chain fatty acids protein 5 (elovl5) is an enzyme that
is crucial in performing the condensation reaction in elongation step in the PUFA
biosynthesis pathway. Together with fatty acid desaturases, it produces
physiologically important fatty acids such as eicosapentaenoic acid (EPA, 20:5n-3),
docosahexaenoic acid (DHA, 22:6n-3) and arachidonic acid (ARA, 20:4n-6) that are
found abundant in fish oil. The function of elovl5 has been studied previously in
human and mouse, suggesting that it is involved in distinct metabolic processes. The
control of elovl5 gene expression mainly occurs at transcription level, therefore,
characterization of elovl5 promoter is vital for the PUFA production. In this study,
elovl5 promoter with a size of 2.8 kb was successfully cloned. By using 5’-RACE
approach, two putative transcription start sites were identified in elovl5 gene.
Bioinformatic analysis of the 2.8 kb promoter region revealed the presence of
SREBP, Sp1 and NF-Y cis-elements which are important in regulating fatty acids
related genes. The 5’end promoter deletion analysis demonstrated that 884 bp
promoter fragment contained the putative SRE binding sites were able to drive basal
transcriptional activity while mutagenesis on the binding sites further showed that
the putative SRE binding sites were important in modulating high level of basal
transcriptional activity of elovl5 promoter. Electrophoretic mobility shift assay
(EMSA) indicates that proximal SRE identified in the promoter region is the
SREBP-1 primary binding site. Lastly, transient transgenesis was carried out and
green fluorescent protein (GFP) was expressed in yolk syncytial layer of the
microinjected zebrafish embryos, showing that the cloned promoter is a functional
promoter. In conclusion, 884 bp of zebrafish elovl5 promoter fragment is able to
drive basal expression and proximal SRE binding site is crucial in regulating
zebrafish elovl5 transcriptional activity.
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Keywords
Functional Characterization Of The Promoter Region , Of The Zebrafish Elovl Family Member 5