Molecular characterization and expression analysis of the autophagic gene Beclin 1 from the purse red common carp (Cyprinus carpio) exposed to cadmium

Beclin 1, the mammalian orthologue of yeast Atg6, has a central role in autophagy, which has been linked to diverse biological processes including immunity, development, tumor suppression, lifespan extension, etc. However, the relevant study about Bedin 1 is rare in fish compared with mammals. In this study, we isolated Beclin 1 gene from the kidney tissue of common carp (Cyprinus carpio) using rapid amplification of cDNA ends (RACE). The deduced amino acid sequence of cloned Bedin 1 comprised 447 amino acids, which showed approximately 80.7% identity and 88.9% similarity to human Beclin I. It possessed a typical Bcl-2 homology domain 3 (BH3) and an evolutionarily conserved domain (ECD). Phylogenetic analysis demonstrated that common carp Beclin 1 formed a dade with zebrafish Bedin I. To explore the relationship between Beclin 1 and cadmium (Cd)-induced injury, a Cd exposure experiment was conducted. The result showed that Cd content was significantly increased in a dose-dependent manner in kidney after Cd exposure. Swelling and vacuolation of renal tubular epithelial cells, and glomerular hyalinization were observed. Renal leukocyte infiltration was diffusely distributed in the interstitial tissue. Real-rime quantitative RT-PCR analysis revealed that the mRNA transcript level of Bedin 1 was markedly up-regulated in a dose-dependent and time-dependent manner after exposure to Cd. Similarly, Westem blot analysis indicated that its protein level was significantly elevated in a dose-dependent manner after Cd treatment. All the results indicate that the common carp Beclin 1 gene may play a regulatory role against Cd toxicity. Crown Copyright (C) 2013 Published by Elsevier Inc. All rights reserved.