Figure 1.

Molecular Mechanism of the PS Gene Editing Approach

First, Cas9 nuclease creates a double-strand break at the target locus. Through homology-directed repair, the splicing acceptor (SA) and human IDUA cDNA (IDUA), and the poly(A) (PA) sequence, are integrated. Through non-homologous end joining, the whole AAV sequence is integrated. Through the interaction between the splicing donor (SD) and SA, the fusion transcript is the same, which includes exon 1 of the albumin gene and the IDUA sequence. Exon 1 primarily encodes a signal peptide, which will be cleaved thereafter. The mature proteins are only the therapeutic IDUA proteins. ITR, inverted terminal repeat; HA, homology arm.