microRNA-122–Argonaute RISC complex binding to engineered miR122BS in AARS2 mRNA 3′UTR (miR-122–RISC–AARS2-3'UTR)

The microRNA-122–Argonaute RISC complex binding to engineered miR122BS in AARS2 mRNA 3′UTR is a specialized molecular interaction designed for tissue-specific gene therapy. AARS2 (Alanyl-tRNA Synthetase 2, Mitochondrial) is a nuclear-encoded enzyme essential for mitochondrial protein synthesis, and its deficiency leads to severe neurological and cardiac disorders (Götz et al., 2011). In gene therapy applications, delivering a functional AARS2 gene can cause unwanted expression in the liver, potentially leading to toxicity or immune-mediated clearance of the vector. To prevent this, researchers incorporate binding sites for miR-122—a microRNA highly specific to hepatocytes—into the 3' untranslated region (3'UTR) of the AARS2 transgene (Jopling, 2010). When the therapeutic mRNA enters liver cells, the endogenous miR-122–Argonaute RISC complex recognizes these sites and silences the mRNA, effectively 'detargeting' the liver while allowing therapeutic expression in the brain or heart (Xie et al., 2011). This mechanism is a critical safety feature in the development of AAV-mediated therapies for mitochondrial aminoacyl-tRNA synthetase deficiencies.

Other names

miR-122-mediated AARS2 mRNA silencing complexLiver-detargeted AARS2 transgene complexAARS2-miR122BS-RISC interactionmiR-122-regulated AARS2 expression system

The endogenous miR-122–Argonaute RISC complex in hepatocytes binds to engineered miR-122 binding sites (miR122BS) within the 3'UTR of the AARS2 transgene mRNA, leading to its degradation or translational repression to prevent liver-specific expression.