Figure 6.

Nuclear miR-320 Working Model

(A) For Cep57, this sense strand-derived promoter RNA did not have a miR-320 binding site. Instead, Cep57 promoter RNA competed for the shared binding site on Cep57 promoter DNA. Therefore, miR-320 led to increased binding of Ago2 on Cep57 promoter DNA but not promoter RNA. (B) Fscn2 promoter RNA (antisense transcript) harbored a miR-320 binding site; in this case, miR-320 seems to bind directly on its promoter RNA, as well as promoter DNA. In either case, miR-320 overexpression led to Cep57 and Fscn2 promoter RNA detachment from the ssDNA promoter; as such, the original effects mediated by promoter RNA were compromised. The activation or repression effect mediated by miRNAs was dependent on the functional properties of promoter RNAs themselves.