Expression and regulation of ccBAX by miR‐124 in the caudal fin cell of C. auratus gibelio upon cyprinid herpesvirus 2 infection

Abstract

Bcl2 family proteins play a critical role in cell death or survival. BAX, the death‐promoting protein of bcl2 family, mediated mitochondrial pathway inducing cells’ apoptosis in mammal. MiRNAs have been implicated as negative regulators down‐regulating genes’ expression after post‐transcriptional level. At present, little is known about the regulatory mechanism of miRNA on the Bcl2 family proteins during CyHV‐2 infection in silver crucian carp (Carassius auratus gibelio). In this study, the ccBAX (silver crucian carp BAX) gene was cloned and expressed, and polyclonal antibodies were raised in mouse against the purified ccBAX‐GST fusion protein. The structure analysis indicated that ccBAX protein included four conserve domains (BH1, BH2, BH3 and transmembrane domains) and the expression of ccBAX protein occurred throughout the cells. Furthermore, two miRNAs (miR‐124 and miRNA‐29b) were identified to negatively regulate ccBAX gene expression in GiCF cell. miR‐124 was found to suppress the expression of WT‐ccBAX (wild type), but not the MT‐ccBAX (mutant). Overall, the results demonstrated that the expression of the ccBAX gene was significantly down‐regulated by miR‐124 in silver crucian carp (Carassius auratus gibelio) during CyHV‐2 infection.

miR‐124 mediates the expression of ccBax to regulate Cyprinid herpesvirus 2 (CyHV‐2)‐induced apoptosis and viral replication

“…CcBax was predicted as one of the candidate target genes of miR‐124 in our previous study (Yu et al, 2021). To investigate the effect of miR‐124 on the expression of ccBax gene, miR‐124 mimics/mimics NC or miR‐124 inhibitor/inhibitor NC was transfected into GiCF cells infected with CyHV‐2.…”

“…Furthermore, miR-124 was reported to inhibit the expression of wild-type ccBax but not mutated one (Yu et al, 2021). Therefore, miR-124 was demonstrated to target the pro-apoptotic ccBax gene.…”

“…Our results showed that overexpression of miR‐124 significantly down‐regulated expression levels of ccBax mRNA and protein. Furthermore, miR‐124 was reported to inhibit the expression of wild‐type ccBax but not mutated one (Yu et al, 2021). Therefore, miR‐124 was demonstrated to target the pro‐apoptotic ccBax gene.…”

“…CcBax was predicted as one of the candidate target genes of miR-124 in our previous study (Yu et al, 2021)…”

“…In our previous study, the pro-apoptotic factor silver crucian carp BAX (ccBax) was significantly up-regulated in CyHV-2-infected GiCF cells, which suggested that ccBax is associated with CyHV-2 replication. Meanwhile, a host-encoded miRNA (miR-124) was found to inhibit ccBax expression by binding to the 3'UTR of ccBax mRNA (Yu et al, 2021). Moreover, the expression patterns of miR-124 and ccBax showed some negative correlation (Fei et al, 2020).…”