Molecular Identification and Functional Characterization of LC-PUFA Biosynthesis Elongase (elovl2) Gene in Chinese Sturgeon (Acipenser sinensis).

Simple Summary: The elongation of very-long-chain fatty acids gene 2 (elovl2) of Chinese sturgeon was identified in acipenseriformes species for the first time. Elovl2 was highly conserved in molecular evolution among vertebrates. Functional characterization in yeast demonstrated that Chinese sturgeon Elovl2 could efficiently elongate C₂₀ (20:4n-6 and 20:5n-3) and C₂₂ (22:4n-6 and 22:5n-3) substrates, confirming its critical roles in long-chain polyunsaturated fatty acid (LC-PUFA) biosynthesis. Diets with different types of PUFAs can affect the transcription levels of elovl2 in Chinese sturgeon. This study enhances our understanding about the evolutionary and functional characteristics of elovl2 and also provides novel insights into the mechanism of LC-PUFA biosynthesis in vertebrates. Elongases of very-long-chain fatty acids (Elovls) are critical rate-limiting enzymes that are involved in LC-PUFA biosynthesis through catalyzing the two-carbon elongation of a pre-existing fatty acyl chain. Thus far, several Elovls have been extensively studied in teleost. However, the functional and physiological roles of Elovls in chondrichthyans have rarely been reported. In this study, we identified and characterized elovl2 from the endangered Chinese sturgeon (Acipenser sinensis) by whole genome scanning. The results show that the coding sequence of elovl2 was 894 bp in length, for a putative protein of 297 amnio acids. Comparative genomic analyses indicated that Chinese sturgeon elovl2 was evolutionarily conserved. Functional characterization in yeast demonstrated that the Chinese sturgeon Elovl2 could efficiently elongate C₂₀ (ARA and EPA) and C₂₂ (22:4n-6 and 22:5n-3) substrates, confirming its critical roles in LC-PUFA biosynthesis. Spatial and temporal expression analyses showed high elovl2 mRNA levels were detected in the liver and brain and showed an increase trend both in embryonic and post-hatching stages. Interestingly, diets with vegetable oils as lipid sources could significantly induce the high expression of elovl2 in Chinese sturgeon, implying that the endogenous LC-PUFA biosynthesis pathway was stimulated by lack of LC-PUFA in their diets. Our findings will enhance our understanding about the evolutionary and functional roles of elovl2 and provide novel insights into the LC-PUFA biosynthesis mechanism in vertebrates. [ABSTRACT FROM AUTHOR]