Jin Wang

Introduction: Defects in RAG1/RAG2 -mediated V(D)J recombination cause severe combined immunodeficiency (SCID), a disorder characterized by the absence of mature T and B lymphocytes resulting from impaired antigen receptor gene rearrangement. Although evolutionary analyses demonstrate strong conservation of the catalytic core domains of RAG1/RAG2 across jawed vertebrates, structural divergence among species highlights the need for physiologically relevant large-animal models to evaluate human disease mechanisms. Pigs represent an advantageous model for human pathologies because of their close immunological and physiological similarities to humans. Methods: In this study, we performed evolutionary profiling, conservation analysis, tertiary structural modeling, and protein docking to characterize pig RAG1 and RAG2 and predict their functional roles in V(D)J recombination. These predictions were experimentally validated through the generation of RAG1 and RAG2 knockout pigs using CRISPR/Cas9-mediated genome editing. Results: Our findings define key structural features of pig RAG1 and RAG2 that are essential for V(D)J recombination and establish an integrated framework that combines comprehensive computational analyses with in vivo experimental validation. Discussion: This approach supports the development of pigs as physiologically relevant models of RAG deficiency and provides a foundation for future studies in pig immunology, genome editing, and translational research. Furthermore, these immunodeficient pigs permit long-term engraftment of human tissue xenografts and stem cell-derived teratomas, thereby enabling investigations of human immune reconstitution, cancer biology, and regenerative medicine. Collectively, this model offers a robust platform for immunotherapy development and for advancing studies in evolutionary and comparative immunology research.

Currently, a major challenge exists in CRISPR-mediated genome editing research in sheep: the low efficiency of exogenous large DNA fragment targeted integration without drug selection or fluorescence enrichment. This restriction significantly impedes the use of precise genome editing in sheep for agricultural, biological, and biomedical purposes. In this study, we employed the strategy of increasing the local concentration of the homologous repair template at the site of the DNA double-strand break (DSB). We achieved this by fusing the DNA binding domain (BD) of the Gal4 protein (Gal4-BD) to the N-terminal end of the SpCas9 protein using a 32-amino acid (aa) flexible linker. Additionally, we incorporated a 17 bp UAS at the 3′ end of the donor template, which can be specifically recognized and bound by Gal-BD. As a result, we observed a significant improvement in the knock-in efficiency of the exogenous large DNA fragment (2997 bp) in sheep fetal fibroblasts (SFFs), increasing it from 5.30% (8/151) to 16.67% (32/192), providing a comparatively efficient and user-friendly method to promote CRISPR-mediated gene knock-in in sheep.

Prion diseases are neurodegenerative disorders characterized by the accumulation of a disease-associated prion protein and apoptotic neuronal death. Previous studies indicated that the ubiquitous expression of c-Abl tyrosine kinase transduces a variety of extrinsic and intrinsic cellular signals. In this study, we demonstrated that a synthetic neurotoxic prion fragment (PrP106-126) activated c-Abl tyrosine kinase, which in turn triggered the upregulation of MST1 and BIM, suggesting the activation of the c-Abl-BIM signaling pathway. The peptide fragment was found to result in cell death via mitochondrial dysfunction in neuron cultures. Knockdown of c-Abl using small interfering RNA protected neuronal cells from PrP106-126-induced mitochondrial dysfunction, production of reactive oxygen species, and apoptotic events inducing translocation of Bax to the mitochondria, cytochrome c release into the cytosol, and activation of caspase-9 and caspase-3. Blocking the c-Abl tyrosine kinase also prevented neuronal cells from PrP106-126-induced apoptotic morphological changes. This is the first study reporting that c-Abl tyrosine kinase as a novel upstream activator of MST1 and BIM plays an important role in prion-induced neuron apoptosis via mitochondrial dysfunction. Our findings suggest that c-Abl tyrosine kinase is a potential therapeutic target for prion disease.