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Figure 1. Types and mechanisms of RNA-based therapies (Created with BioRender.com). (A) RNA interference. Long double-stranded RNA and precursor microRNA are processed by Dicer into siRNAs and mature miRNAs, which are loaded into RISCs for RNA targeting, degradation, or translational repression; (B) mRNA vaccines. mRNAs are delivered to dendritic cells by lipid nanoparticles, released into the cytoplasm, and translated into antigenic proteins by ribosomes. Some antigenic proteins are degraded into small peptides by the proteasome and are presented to the surface of CD8+ T cells by MHC I. CD8+ cytotoxic T cell-mediated immunity kills infected cells by secretion of perforin or granzyme. Other antigenic proteins are degraded in lysosomes and displayed on the surface of CD4+T cells by MHC II. B cell-mediated humoral immunity uses antibodies to neutralize pathogens; (C) Antisense oligonucleotides. ASO can regulate the expression of target genes by two mechanisms: (1) an occupancy-only mechanism and (2) an RNA degradation mechanism.