A 314-bp SINE Insertion in the ZNF2 promoter region may act as a repressor related to regulation of fat deposition in pigs

Retrotransposons, a type of DNA fragment that can mobilize itself on genome, can generate genetic variations and develop for molecular markers based on the insertion polymorphism. Zinc finger proteins (ZNFs) are among the most abundant proteins in eukaryotic animals, and their functions are extraordinarily diverse and particularly important in gene regulation. In the current study, bioinformatic prediction was performed to screen for retrotransposon insertion polymorphisms (RIPs) in 6 ZNF genes (ZNF2, ZNF3, ZNF7, ZNF8, ZNF10 and ZNF12). 6 RIPs in these ZNFs, including 1 short interspersed nuclear element (SINE) RIP in intron 1 and 1 long interspersed nuclear element 1 (L1) RIP in intron 3 of ZNF2, 1 SINE RIP in 5’ flanking region and 1 SINE RIP in intron 2 of ZNF3, 1 SINE RIP in 3’ UTR of ZNF7 and 1 L1 RIP in intron 2 of ZNF12, were discovered and their presence was confirmed by PCR. The impact of the SINE RIP in the first intron of ZNF2, which is close to the core promoter of ZNF2, on the gene activity was investigated by dual-luciferase assay in 3 cell lines. Our results showed that the SINE insertion in the intron 1 of ZNF2 repressed the core promoter activity extremely significantly (P<0.01) in cervical cancer cells and porcine primary embryonic fibroblasts (HeLa and PEF). SINE may act as a repressor. This SINE RIP also significantly (P<0.05) affected the corrected back fat thickness in Yorkshire pigs. The corrected back fat thickness of individuals with SINE insertion in the first intron of ZNF2 was significantly (P<0.05) higher than that of individuals without SINE insertion. In summary, our data suggested that RIPs play important roles in the genetic variations of these ZNF genes and SINE RIP in the intron 1 of ZNF2 may provide a useful molecular marker for the screening of fat deposition in the pig breeding.