Molecular cloning, characterization and expression modulation of four ferritins in black carp Mylopharyngodon piceus in response to Aeromonas hydrophila challenge

As ubiquitous and conserved proteins, ferritin (FT) plays important roles in immune system and iron storage system. Four cDNAs encoding ferritin (MpFT) were cloned from black carp Mylopharyngodon piceus using homology cloning and rapid amplification of cDNA ends techniques. There were 177, 177, 176 and 173 amino acids in the MpFT-H1 alpha, MpFT-H1 beta, MpFT-M and MpFT-L, respectively. BLAST analysis reveals that MpFTs shares high identifies with other known FTs from zebrafish, Rainbow trout and Human, etc. A typical iron-responsive element (IRE) was predicted in the 5'-untranslated region (UTR) of MpFT-H1 alpha and MpFT-M, respectively. The relative expression levels of MpFT1 a were higher in the blood, liver and heart of black carp according to RT-PCR assays (P < 0.05). Higher expression levels of MpFT1b were shown in the liver and heart of black carp (P < 0.05). Relative higher transcriptional levels of MpFTL could be observed in the liver, blood and brain (P < 0.05). And higher expression levels of MpFTM were shown in the liver and intestine compared with these of in the muscle of black carp according to RT-PCR assays (P < 0.05). And the expression variations of FT-M and FT-L were more sensitive than these of FT-H1a and FT-H1b in the blood of black carp post infection. Similarly, the mRNA expression profiles of four FTs could also be differently upregulated and reached to the peak expression levels at 12h, 12h, 6h and 48h after Aeromonas hydrophila infection in the liver of black carp. In the intestine, all the transcription variations of four FTs were reached to highest levels at 24 h post infection in this study. As a whole, these results indicated that four MpFTs might play important roles in innate immune defense during A. hydrophila infection in this study.