Construction And Applications Of Ifnβ-luciferase Reporter Mouse

As an important cytokine released by the body’s innate immune system in response to the invasion of external pathogens,IFN-βplays an essential role in resisting viral infection and tumorigenesis.Besides,the excessive secretion of IFN-βis considered as the main inducement of autoimmune diseases.The expression level of IFN-βis an important indicator that reflects the activation state of innate immunity.Tracking the expression of endogenous IFN-βis crucial for monitoring the body’s environmental immune homeostasis.However,due to the lack of sensitive detection systems,when and where IFN-βis produced in vivo is still poorly understood.In this study,in order to real-time monitor the expression of endogenous IFN-βof mice in an immune activated state through in vivo imaging system,we constructed a novel reporter mouse synchronously and stably expressed luciferase and IFN-βgenes with the CRISPR-Cas9 gene editing system,in which the luciferase gene was intergrated into the IFN-βgenome through the cell homologous recombination repair mechanism.To validate the luciferase as a sensitive reporter for IFN-βin Ifn-β^lun/lucmice,at the cellular level,we confirmed that various exogenous stimulations induced the simultaneous and consistent expression of luciferase and IFN-βin Ifn-β^lun/lucprimary lung fibroblasts and bone marrow-derived macrophages treated with exgenous stimulations by q-RT-PCR,Western-blot,and luciferase reporter assays,which indicated a high sensibility of luciferase as a reporter for detecting expression of IFN-β.At the mouse level,we detected the luciferase activity in Ifn-β^luc/lucmice injected with the STING agonist CMA,by which visualized the dynamic expression of IFN-βat indicated time points via in vivo imaging system.The results showed that CMA time gradient stimulation induced the simultaneous expression of luciferase and IFN-β,which exhibited a strong time-difference and tissue-specific manner,and which were mainly concentrated in thymus,lung and kidney.Next,we observed the luciferase activity in Ifn-β^lun/lucmice infected with HSV-1 by in vivo imaging.The results indicated that HSV-1 infection induced the synchronously expression of luciferase and IFN-β,which presented tissue-specific and were mainly concentrated in the liver.Futhermore,we crossed Ifn-β^luc/lucmice with TREX1deletion-mediated autoimmune disease mouse model to obtain Trex1^-/-Ifn-β^luc/lucmice,in which we found that the TREX1 deletion induced the simultaneous expression of luciferase and IFN-βthrough in vivo imaging system,and were mainly appeared in heart,lung,thymus.The significance and mechanism of the timely and spatial distribution of IFN-?upon various immune stimulations need to be futher studied.In summary,Ifn-β^luc/lucmice can be applied for sensitively monitoring the expression of endogenous IFN-βinduced by exogenous small molecule drug stimulation,viral infection,and endogenous autoimmune stress,which is of great significance for exploring mechanism of viral infections and autoimmune diseases and provides an ideal visualization model for the screening of drugs for immune diseases.