Drug repurposing for metabolic disorders: Scientific, technological and economic issues.

Obesity, diabetes, and other metabolic disorders place a huge burden on both the physical health and financial well-being of the community. While the need for effective treatment of metabolic disorders remains urgent and the reality is that traditional drug development involves high costs and a very long time with many pre-clinical and clinical trials, the need for drug repurposing has emerged as a potential alternative. Scientific evidence has shown the anti-diabetic and anti-obesity effects of old drugs, which were initially utilized for the treatment of inflammation, depression, infections, and even cancers. The drug library used modern technological methods to conduct drug screening. Computational molecular docking, genome-wide association studies, or omics data mining are advantageous and unavoidable methods for drug repurposing. Drug repurposing offers a promising avenue for economic efficiency in healthcare, especially for less common metabolic diseases, despite the need for rigorous research and validation. In this chapter, we aim to explore the scientific, technological, and economic issues surrounding drug repurposing for metabolic disorders. We hope to shed light on the potential of this approach and the challenges that need to be addressed to make it a viable option in the treatment of metabolic disorders, especially in the future fight against metabolic disorders.

Rationally engineered Staphylococcus aureus Cas9 nucleases with high genome-wide specificity.

RNA-guided CRISPR-Cas9 proteins have been widely used for genome editing, but their off-target activities limit broad application. The minimal Cas9 ortholog from Staphylococcus aureus (SaCas9) is commonly used for in vivo genome editing; however, no variant conferring high genome-wide specificity is available. Here, we report rationally engineered SaCas9 variants with highly specific genome-wide activity in human cells without compromising on-target efficiency. One engineered variant, referred to as SaCas9-HF, dramatically improved genome-wide targeting accuracy based on the genome-wide unbiased identification of double-stranded breaks enabled by sequencing (GUIDE-seq) method and targeted deep sequencing analyses. Among 15 tested human endogenous sites with the canonical NNGRRT protospacer adjacent motif (PAM), SaCas9-HF rendered no detectable off-target activities at 9 sites, minimal off-target activities at 6 sites, and comparable on-target efficiencies to those of wild-type SaCas9. Furthermore, among 4 known promiscuous targeting sites, SaCas9-HF profoundly reduced off-target activities compared with wild type. When delivered by an adeno-associated virus vector, SaCas9-HF also showed reduced off-target effects when targeting VEGFA in a human retinal pigmented epithelium cell line compared with wild type. Then, we further altered a previously described variant named KKH-SaCas9 that has a wider PAM recognition range. Similarly, the resulting KKH-HF remarkably reduced off-target activities and increased on- to off-target editing ratios. Our finding provides an alternative to wild-type SaCas9 for genome editing applications requiring exceptional genome-wide precision.