Micro RNA miR-726-3p targets CYB5A in Hen ovaries to modulate granulosa cell proliferation and differentiation

Follicular development is closely related to poultry egg production. Granulosa cells (GCs) are important components of follicles and vital for follicular selection and hierarchical development. Previous studies demonstrated that miRNAs play a key role in controlling follicular development and atresia. However, biological effects and mechanism of action of miR-726-3p on GC proliferation and differentiation of hen ovaries remain poorly understood. In this study, we compared miRNA profiles in larger white follicles (LWF), along with large (LYF) and small yellow follicles (SYF), to identify target genes related to follicular development. Nine cDNA libraries were constructed, in which 61 miRNA-linked genes were significantly differentially expressed (DE). MiR-726-3p was the most crucial co-DE miRNA and, therefore, was chosen for further evaluation. Using bioinformatics and the luciferase reporter assay, we identified CYB5A as the target of miR-726-3p. Over-expression of miR-726-3p significantly negatively regulated GC proliferation, differentiation and knocking down CYB5A expression supported miR-726-3p overexpression. Overall, miR-726-3p suppresses GC proliferation and differentiation by targeting CYB5A, thus providing new insight into the mechanism that underlies hen follicle development.