Genome-edited rabbits:Unleashing the potential of a promising experimental animal model across diverse diseases

Animal models are extensively used in all aspects of biomedical research,with substantial contributions to our understanding of diseases,the development of pharmaceuticals,and the exploration of gene functions.The field of genome modification in rabbits has progressed slowly.However,recent advancements,particularly in CRISPR/Cas9-related technologies,have catalyzed the successful development of various genome-edited rabbit models to mimic diverse diseases,including cardiovascular disorders,immunodeficiencies,agingrelated ailments,neurological diseases,and ophthalmic pathologies.These models hold great promise in advancing biomedical research due to their closer physiological and biochemical resemblance to humans compared to mice.This review aims to summarize the novel gene-editing approaches currently available for rabbits and present the applications and prospects of such models in biomedicine,underscoring their impact and future potential in translational medicine.

Efficient multinucleotide deletions using deaminase-Cas9 fusions in human cells

CRISPR/Cas9 system is a robust genome editing platform in biotechnology and medicine.However,it generally produces small insertions/deletions(indels,typically 1-3 bp)but rarely induces larger deletions in specific target sites.Here,we report a cytidine deaminase-Cas9 fusion-induced deletion system(C-DEL)and an adenine deaminase-Cas9 fusion-induced deletion system(A-DEL)by combining Cas9 with rat APOBEC1(r A1)and Tad A 8e,respectively.Both C-DEL and A-DEL improve the efficiency of deletions compared with the conventional Cas9 system in human cells.In addition,the C-DEL system generates a considerable fraction of predictable multinucleotide deletions from 5’-deaminated C bases to the Cas9-cleavage site and increases the proportion of larger deletions at the target loci.Taken together,the CDEL and A-DEL systems provide a practical strategy for producing efficient multinucleotide deletions,expanding the CRISPR/Cas9 toolsets for gene modifications in human cells.

Targeted mutagenesis in rabbit using an engineered BhCas12b variant

Dear Editor,The clustered regularly interspaced short palindromic repeat(CRISPR)and CRISPR-associated protein(CRISPR–Cas)system has exhibited powerful abilities to manipulate genomes of animals and plants(Knott and Doudna,2018).Up to now,numerous Cas nucleases have been harnessed for genome editing in human cells,such as Cas9,Cas12a(also known as Cpf1),and Cas12b(also termed C2c1).Cas12b,a Class 2 type V-B CRISPR system,generates staggered double-strand breaks(DSBs)in the target DNA(Stella et al.,2017)and recognizes a distal 5′-T-rich protospacer adjacent motif(PAM)sequence(Shmakov et al.,2015),making it a complement to Cas9(recognizing 5′-NGG-3′PAM)in genome editing.Three Cas12b nucleases have been engineered for targeted genome editing in mammals or plants:BhCas12b v4(Strecker et al.,2019),BvCas12b(Strecker et al.,2019),and AaCas12b(Teng et al.,2018).However,they have not been compared parallelly with each other.In this study,we compared the three Cas12b proteins for genome editing in mammalian cells.