CgVDAC2 participated in haemocyte mitophagy induced by Vibrio splendidus in the Pacific oyster Crassostrea gigas

VDAC2 (Voltage dependent anion channel 2) is a highly conserved pore-forming protein expressed in the outer membrane of eukaryotic mitochondria. In the present study, CgVDAC2 identified from Crassostrea gigas regulated the mitophagy of haemocytes induced by Vibrio splendidus. CgVDAC2 was distributed in the cytoplasm of three subpopulations of haemocytes. After V. splendidus stimulation, the mRNA and protein expressions of CgVDAC2 were induced in haemocytes. Furthermore, the green signals of CgVDAC2 were colocalized with the red signals of mitochondria and Mtphagy Dye, respectively. And their co-localization values were both increased significantly in haemocytes at 12 h after V. splendidus stimulation, respectively. In siCgVDAC2-treated oysters, the mRNA expressions of mitophagy-related genes (CgLC3, CgPINK1, CgParkin1, CgPHB2, and CgATG16L) and the levels of mitophagy decreased significantly in haemocytes after V. splendidus stimulation. In addition, both the fluorescence intensities of the JC-1 monomer/aggregate ratio (Q4/Q2) and mitochondrial reactive oxygen species (mtROS) increased significantly. Collectively, all the results indicated that CgVDAC2 participated in oyster antibacterial immune response through regulating the haemocyte mitophagy.