149 PRODUCTION OF KNOCK-DOWN MICE WITH shRNA CYTOCHROME P-450 4F16 GENE AND REDUCTION OF THE IMMUNE SYSTEM.
ABSTRACT The putative mouse homologue of cytochrome P-450 4F16 (Cyp4f16) is induced by interleukin-1 (Il-1), interleukin-6 (Il-6) and tumour necrosis factor-α (Tnf-α) and repressed by interleukin-10 (Il-10) and lipopolysaccharide (LPS). The Cyp4F16 is a subfamily of Cyp4F and it is also related to eicosanoids that are important mediators in the inflammatory cascade (Cui et al. 2001). To investigate the role of Cyp4F16, in the present study, we report the production of Cyp4f16 gene knock-down mice in 2 strains of mice, namely A/J and C57BL/6. The A/J is susceptible to infection and it is associated with Cyp4F16, whereas C57BL/6 is relatively resistant to infection. An shRNA-Cyp4F16 expression vector was microinjected into pronuclei of fertilized mouse oocytes and the embryos were transferred into pseudopregnant recipients. As a result, 25 and 50 mice were produced in the A/J and C57BL, respectively. Two mice in the A/J strain and 6 in the C57BL strain were confirmed by PCR as transgenic. Organs were collected in each of the lines produced by inbreeding and screened with real-time PCR for Cyp4f16 transcripts. The Cyp4f16 gene was expressed in a tissue-specific manner with high expression in the pancreas, spleen and lung and a lower level of transcription in the heart, muscle, thymus, kidney, testis and liver. In the spleen of transgenic Cyp4f16 knock-down mice, Cyp4f16 mRNA and protein expression levels were significantly lower than those of wild-type mice. The A/J Cyp4f16 knock-down mice suffered an inflammatory skin disease and tumours, but wild-type A/J mice and knock-down C57BL mice did not. Taken together, these results suggest that Cyp4f16 may play a regulatory role in the immune system and point to the use of the Cyp4f16 knock-down mouse as an experimental animal model for the study of the inflammatory process.