Characterization of Oyster Voltage-Dependent Anion Channel 2 (VDAC2) Suggests Its Involvement in Apoptosis and Host Defense

• Published in: PloS one 2016-01, Vol.11 (1), p.e0146049-e0146049
• Main Authors: Li, Yingxiang, Zhang, Linlin, Qu, Tao, Li, Li, Zhang, Guofan
• Format: Article
• Language: English
• Subjects: Adaptation, Physiological; Adaptive Immunity; Amino Acid Motifs; Amino Acid Sequence; Amino acids; Animals; Anions; Antimicrobial peptides; Apoptosis; Apoptosis - genetics; Apoptosis - radiation effects; Base Sequence; bcl-2 Homologous Antagonist-Killer Protein - metabolism; Biotechnology; Bivalvia; Cloning, Molecular; Conserved sequence; Cytochrome; Developmental stages; Electric potential; Engineering; Gene expression; Gene Expression Regulation, Developmental; Health aspects; HeLa Cells; Hemocytes; Hemocytes - radiation effects; Herpesviridae; Humans; Hybrid systems; Immunity; Immunoprecipitation; Infections; Intertidal environment; Irradiation; Laboratories; Light irradiation; Marine biology; Metabolites; Mitochondria; Mitochondrial DNA; Mitochondrial Proteins - chemistry; Mitochondrial Proteins - genetics; Mitochondrial Proteins - isolation & purification; Mitochondrial Proteins - physiology; Molecular Sequence Data; Mollusca; Mollusks; Open Reading Frames - genetics; Organ Specificity; Ostreidae - genetics; Ostreidae - immunology; Ostreidae - metabolism; Ostreidae - virology; Oysters; Parasites; Pattern analysis; Protein Interaction Mapping; Proteins; Recombinant Fusion Proteins - metabolism; Ribonucleic acid; RNA; RNA Interference; RNA-mediated interference; Science; Sequence Alignment; Sequence Homology, Amino Acid; Signal Transduction; Studies; Transfection; Two-Hybrid System Techniques; Ultraviolet radiation; Ultraviolet Rays; Viral infections; Voltage; Voltage-Dependent Anion Channel 2 - chemistry; Voltage-Dependent Anion Channel 2 - genetics; Voltage-Dependent Anion Channel 2 - isolation & purification; Voltage-Dependent Anion Channel 2 - physiology; Yeast
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0146049

Genomic and transcriptomic studies have revealed a sophisticated and powerful apoptosis regulation network in oyster, highlighting its adaptation to sessile life in a highly stressful intertidal environment. However, the functional molecular basis of apoptosis remains largely unexplored in oysters. In this study, we focused on a representative apoptotic gene encoding voltage-dependent anion channel 2 (VDAC2), a porin that abounds at the mitochondrial outer membrane. This is the first report on the identification and characterization of a VDAC gene in the Pacific oyster, Crassostrea gigas (CgVDAC2). The full length of CgVDAC2 was 1,738 bp with an open reading frame of 843 bp that encoded a protein of 281 amino acids. A four-element eukaryotic porin signature motif, a conserved ATP binding motif, and a VKAKV-like sequence were identified in the predicted CgVDAC2. Expression pattern analysis in different tissues and developmental stages as well as upon infection by ostreid herpesvirus 1 revealed the energy supply-related and immunity-related expression of CgVDAC2. CgVDAC2 was co-localized with mitochondria when it was transiently transfected into HeLa cells. Overexpression of CgVDAC2 in HEK293T cells suppressed the UV irradiation-induced apoptosis by inhibiting the pro-apoptotic function of CgBak. RNA interference induced reduction in CgVDAC2 expression showed a promoted apoptosis level upon UV light irradiation in hemocytes. The yeast two-hybrid system and co-immunoprecipitation assay indicated a direct interaction between CgVDAC2 and the pro-apoptotic protein CgBak. This study revealed the function of VDAC2 in oyster and provided new insights into its involvement in apoptosis modulation and host defense in mollusks.