Suxiang John Chen Dr

Therapeutic nucleic acids such as antisense oligonucleotides (AOs) can specifically bind to target RNA and manipulate gene expression through different mechanism of actions, including RNase H mediated RNA degradation, splice modulation, and translational repression. So far, the United States Food and Drug Administration has approved seven AO drugs for the therapies of different human diseases. Among them, four drugs (eteplirsen, golodirsen, nusinersen, milasen) modulate splicing, and rescue the production of functional essential proteins by restoring ruined open reading frames due to mutations within genes. This thesis explores the potential of novel chemically-modified splice-modulating AOs in tackling type 2 diabetes (T2D) and Duchenne muscular dystrophy (DMD). Chapter one provides an introduction of different types of therapeutic nucleic acids. Chapter two focused on developing AOs targeting protein tyrosine phosphatase 1B (PTP1B), a validated therapeutic target of T2D. An AO candidate, PTPN1 1E2A (+5+29), was identified to efficiently skip exon-2 of PTPN1 RNA inducing premature termination codons in exon-3, thereby reducing the production of full-length, functional PTP1B proteins. Chapter three presents the work on design, synthesis and evaluation of splice-modulating chimeric AOs containing novel nucleotide analogues for exon skipping in H2K mdx myoblast, using DMD as a disease model. Morpholino nucleic acid modified 2'-O-Methyl (2'-OMe) AO mixmer exhibited comparable exon skipping ability as uniformly modified 2'-OMe AO. Locked nucleic acid (LNA) modified 2'-Fluoro (2'-F) AOs showed improved drug-like properties than 2'-OMe modified 2'-F AOs. In summary, the thesis expands the applicability of AOs in the therapy of T2D through downregulating PTP1B protein expression by splice modulation; the thesis also expands the scope of utilizing nucleotide analogues in splice modulation application by constructing AO chimeras, demonstrating the feasibility of using these analogues for optimizing AOs in terms of improved drug-like properties.