Current therapies for osteoarthritis and prospects of CRISPR-based genome,epigenome,and RNA editing in osteoarthritis treatment

Osteoarthritis(OA)is one of the most common degenerative joint diseases worldwide,causing pain,disability,and decreased quality of life.The balance between regeneration and inflammation-induced degradation results in multiple etiologies and complex pathogenesis of OA.Currently,there is a lack of effective therapeutic strategies for OA treatment.With the development of CRISPR-based genome,epigenome,and RNA editing tools,OA treatment has been improved by targeting genetic risk factors,activating chondrogenic elements,and modulating inflammatory regulators.Supported by cell therapy and in vivo delivery vectors,genome,epigenome,and RNA editing tools may provide a promising approach for personalized OA therapy.This review summarizes CRISPR-based genome,epigenome,and RNA editing tools that can be applied to the treatment of OA and provides insights into the development of CRISPR-based therapeutics for OA treatment.Moreover,in-depth evaluations of the efficacy and safety of these tools in human OA treatment are needed.

CRISPR-assisted transcription activation by phaseseparation proteins

The clustered regularly interspaced short palindromic repeats(CRISPR)-Cas9 system has been widely used for genome engineering and transcriptional regulation in many different organisms.Current CRISPR-activation(CRISPRa)platforms often require multiple components because of inefficient transcriptional activation.Here,we fused different phase-separation proteins to dCas9-VPR(dCas9-VP64-P65-RTA)and observed robust increases in transcriptional activation efficiency.Notably,human NUP98(nucleoporin 98)and FUS(fused in sarcoma)IDR domains were best at enhancing dCas9-VPR activity,with dCas9-VPR-FUS IDR(VPRF)outperforming the other CRISPRa systems tested in this study in both activation efficiency and system simplicity.dCas9-VPRF overcomes the target strand bias and widens gRNA designing windows without affecting the off-target effect of dCas9-VPR.These findings demonstrate the feasibility of using phase-separation proteins to assist in the regulation of gene expression and support the broad appeal of the dCas9-VPRF system in basic and clinical applications.