Accelerated discovery and miniaturization of novel single-stranded cytidine deaminases.

Cytidine base editors (CBEs) hold significant potential in genetic disease treatment and in breeding superior traits into animals. However, their large protein sizes limit their delivery by adeno-associated virus (AAV), given its packing capacity of <4.7 kb. To overcome this, we employed a web-based fast generic discovery (WFG) strategy, identifying several small ssDNA deaminases (Sdds) and constructing multiple Sdd-CBE 1.0 versions. SflSdd-CBE 1.0 demonstrated high C-to-T editing efficiency, comparable to AncBE4max, while SviSdd-CBE 1.0 exhibited moderate C-to-T editing efficiency with a narrow editing window (C3 to C5). Utilizing AlphaFold2, we devised a one-step miniaturization strategy, reducing the size of Sdds while preserving their efficiency. Notably, we administered AAV8 expressing PCSK9 targeted sgRNA and SflSdd-CBEs (nSaCas9) 2.0 into mice, leading to gene-editing events (with editing efficiency up to 15%) and reduced serum cholesterol levels, underscoring the potential of Sdds in gene therapy. These findings offer new single-stranded editing tools for the treatment of rare genetic diseases.

Effective inhibition of PDCoV infection in chimeric APN gene-edited neonatal pigs.

Porcine deltacoronavirus (PDCoV), an emerging enteropathogenic coronavirus, is a serious threat to piglets and has zoonotic potential. Here, we aimed to further explore the role of aminopeptidase N (APN) as a receptor for PDCoV and test the inhibitory effect of a chimeric APN protein strategy on PDCoV infection. PK-15 cells and LLC-PK1 cells expressing chimeric APN were selected and infected with PDCoV. Viral replication was significantly decreased in these chimeric APN cells compared with that in control group cells. To further characterize the effect of the chimeric APN strategy on PDCoV infection in vitro, primary intestinal epithelial cells isolated from chimeric APN pigs were inoculated with PDCoV. Viral challenge of these cells led to decreased PDCoV infection. More importantly, virally challenged chimeric APN neonatal piglets displayed reduced viral load, significantly fewer microscopic lesions in the intestinal tissue, and no diarrhea. Taken together, these findings deepen our understanding of the mechanism of PDCoV infection and provide a valuable model for the production of disease-resistant animals. IMPORTANCE: Porcine deltacoronavirus (PDCoV), an emerging enteropathogenic coronavirus, causes diarrhea in piglets and possesses the potential to infect humans. However, there are currently no effective measures for the prevention or control of PDCoV infection. Here, we have developed PK-15 cells, LLC-PK1 cells, and primary intestinal epithelial cells expressing chimeric APN, and viral challenge of these cells led to decreased PDCoV infection. Furthermore, virally challenged chimeric APN neonatal piglets displayed reduced viral load, significantly fewer microscopic lesions in the intestinal tissue, and no diarrhea. These data show that chimeric APN is a promising strategy to combat PDCoV infection.

Identification and Functional Analysis of the Regulatory Elements in the pHSPA6 Promoter.

Functional and expressional research of heat shock protein A6 (HSPA6) suggests that the gene is of great value for neurodegenerative diseases, biosensors, cancer, etc. Based on the important value of pigs in agriculture and biomedicine and to advance knowledge of this little-studied HSPA member, the stress-sensitive sites in porcine HSPA6 (pHSPA6) were investigated following different stresses. Here, two heat shock elements (HSEs) and a conserved region (CR) were identified in the pHSPA6 promoter by a CRISPR/Cas9-mediated precise gene editing strategy. Gene expression data showed that sequence disruption of these regions could significantly reduce the expression of pHSPA6 under heat stress. Stimulation studies indicated that these regions responded not only to heat stress but also to copper sulfate, MG132, and curcumin. Further mechanism studies showed that downregulated pHSPA6 could significantly affect some important members of the HSP family that are involved in HSP40, HSP70, and HSP90. Overall, our results provide a new approach for investigating gene expression and regulation that may contribute to gene regulatory mechanisms, drug target selection, and breeding stock selection.

Panax Notoginseng Saponins Inhibits Ventricular Remodeling after Myocardial Infarction in Rats Through Regulating ATF3/MAP2K3/p38 MAPK and NF κ B Pathway.

OBJECTIVE: To explore whether Panax notoginseng saponins (PNS) exhibits heart protective effect in myocardial infarction (MI) rats and to identify the potential signaling pathways involved. METHODS: MI rats induced by ligating the left anterior descending (LAD) coronary artery were assigned to sham coronary artery ligation or coronary artery ligation. Totally 36 Sprague-Dawley rats were randomly divided into sham group (distilled water, n=9), MI group (distilled water, n=9), PNS group (PNS, 40 mg/kg daily, n=9) and fosinopril group (FIP, 1.2 mg/kg daily, n=9) according to a random number table. The left ventricular morphology and function were conducted by echocardiography. Histological alterations were evaluated by the stainings of HE and Masson. The serum levels of C reactive protein (CRP), tumor necrosis factor α (TNF-α), growth differentiation factor-15 (GDF-15) and the ratio of metalloproteinase-9 (MMP-9) and tissue inhibitor of MMP-9 (TIMP-1) were determined by ELISA. The levels of activating transcription factor 3 (ATF3), mitogen-activated protein kinase kinase 3 (MAP2K3), p38 mitogen-activated protein kinase (p38 MAPK), phosphorylation of p38 MAPK (p-p38 MAPK), transforming growth factor-ß (TGF-ß1), collagen I, nuclear factor kappa B p65 (NFκB p65), phosphorylation of NFκB p65 (p-NFκB p65), and phosphorylation of inhibitory kappa Bα (p-Iκ Bα) in hearts were measured by Western blot and immunohistochemical staining, respectively. RESULTS: PNS improved cardiac function and fibrosis in MI rats (P<0.05). The serum levels of CRP, TNF-α, GDF-15 and the ratio of MMP9/TIMP1 were reversed by PNS in MI rats. The expressions of TGF-ß1, collagen I, MAP2K3, p38 MAPK, p-p38 MAPK, NFκB p65, p-NFκB p65, and p-IκBα were down-regulated, while ATF3 increased with the treatment of PNS (P<0.05). CONCLUSIONS: PNS may improve cardiac function and fibrosis in MI rats via regulating ATF3/MAP2K3/p38 MAPK and NFκB signaling pathways. These results suggest the potential of PNS in preventing the development of ventricular remodeling in MI rats.

A CRISPR-engineered swine model of COL2A1 deficiency recapitulates altered early skeletal developmental defects in humans.

Loss-of-function mutations in the COL2A1 gene were previously described as a cause of type II collagenopathy (e.g., spondyloepiphyseal dysplasia, Stickler syndrome type I), a major subgroup of genetic skeletal diseases. However, the pathogenic mechanisms associated with COL2A1 mutations remain unclear, and there are few large-mammal models of these diseases. In this study, we established a swine model carrying COL2A1 mutations using CRISPR/Cas9 and somatic cell nuclear transfer technologies. Animals mutant for COL2A1 exhibited severe skeletal dysplasia characterized by shortened long bones, abnormal vertebrae, depressed nasal bridge, and cleft palate. Importantly, COL2A1 mutant piglets suffered tracheal collapse, which was almost certainly the cause of their death shortly after birth. In conclusion, we have demonstrated for the first time that overt and striking skeletal dysplasia occurring in human patients can be recapitulated in large transgenic mammals. This model underscores the importance of employing large animals as models to investigate the pathogenesis and potential therapeutics of skeletal diseases.