Fig. 2

The main mechanisms of ASO regulate genes. A Downregulation mechanism of degradation and steric blockage simultaneously; ①. The ASO-mRNA double strands as a substrate recruit RNase H1, leading to degradation of the target transcript. ②. ASOs enter the RISC including a part in Ago 2, and become the guide strand. Then direct the RISC to mRNA. B Downregulation mechanism of steric blockage; ③. ASOs bind to pre-mRNA to alter polyadenylation position, and decrease mRNA stability and levels. ④. ASOs bind to the most 5ʹ region of mRNAs to avoid the binding of translation initiation factors, inhibiting translation. C Upregulation mechanism of steric blockage; ⑤. ASOs inhibit miRNA function to increase the expression of their target mRNA. ⑥. ASOs can enhance translation by inhibiting upstream open reading frames (uORFs), a translation suppression element