An integrin alpha 4 (ChIntα 4) from oyster Crassostrea hongkongensis mediates the hemocytes phagocytosis towards Vibrio alginolyticus

Integrins, a family of cell adhesion transmembrane receptors, mediate cell adhesion, migration, proliferation, apoptosis, and phagocytosis. In the present study, an integrin ChInt alpha 4 from Crassostrea hongkongensis was characterized to investigate its role in defensing against pathogenic bacterium Vibrio alginolyticus. The full-length cDNA sequence of ChInt alpha 4 was 3572 bp with an open reading frame (ORF) of 3168 bp, which encoded a polypeptide with 1055 amino acids. The mRNA expression of ChInt alpha 4 in the hemocytes was significantly up regulated at 6 h and 24 h post V. alginolyticus stimulation (p < 0.01). The recombinant ChInt alpha 4 protein could agglutinate the rabbit red blood cells and Gram-negative bacteria V. alginolyticus and Escherichia coli. Moreover, the phagocytic activity of the hemocytes was significantly down-regulated from 46.9% to 32.7% when blocked with anti-ChInt alpha 4 antibody, and it was significantly up-regulated from 42.7% to 59.5% post transfection with pCI-neo-ChInt alpha 4 plasmid (p < 0.05). In conclusion, these findings demonstrated that ChInt alpha 4 might be involved in resisting V. alginolyticus infection and regulating phagocytosis as a cell adhesion receptor in C. hongkongensis.

Automated summary

The study characterized an integrin family protein, ChInt alpha 4, in Crassostrea hongkongensis and found that it plays an important role in defending against pathogenic bacterium infection and regulating phagocytosis.