| Recent evidence shows that mRNA degradation is a major control point in the regulation of gene expression. APE1, apurinic/apyrimidinic DNA endonuclease 1, has recently been discovered to possess an endoribonuclease activity against c-myc messenger RNA (mRNA) in vitro . We showed that APE1 shares catalytic residues to cleave both RNA and AP-DNA. Our results also suggested that the roles of active site residues in each reaction are not entirely identical. A consensus RNA secondary structures and sequences that are preferentially cleaved by APE1 were determined. Our results revealed that APE1 has a preference for cleaving the single stranded regions or weakly base paired regions of the RNA. Also, preferred sequences of cleavage were determined to be UA, UG, and CA. When APE1 was knocked down in HeLa cells, an increased level of c-myc mRNA and half-life was detected. This demonstrated that APE1 is involved in the regulation of c-myc mRNA turnover. |
