Co-expression of human proteins (IL-10, TPO and/or Lactoferrin) into milk of cross-breed transgenic mouse

Abstract

We have previously produced transgenic (TG) mice expressing the human lactoferrin (hLF), interleukin.10 (hIL.10), and thrombopoietin (hTPO) proteins in the milk. In this study, we examined whether simple crossbreeding between two kinds of a single transgenic mouse can produce double transgenics co.expressing two human proteins.. The hLF male, and the hIL.10 male were crossbred with the hIL.10 and hTPO females, and the hTPO female, respectively. PCR analysis for genotyping showed 32%, 23%, and 24% double transgenic rates for hLF/hIL.10, hLF/hTPO, and hIL.10/hTPO transgenes, respectively. We analyzed the expression levels of the human proteins from double transgenic mice and compared those with their single transgenic siblings. All double transgenic co.expressed two human proteins at comparable levels to singles’, unless hTPO was not co.expressed: for hLF, 1.1 mg/ml in hLF/hIL.10, whereas 0.5 mg/ml in hLF/hTPO; for hIL.10, 4.1 mg/ml in hIL.10/hLF, whereas 1.4 mg/ml in hIL.10/hTPO. The downregulation of hTPO to half level of singles’ was observed in double transgenic mice. The possible reason why hTPO co.expressed might lead to down.regulation of another human protein was discussed. These results suggested that double transgenic generated by crossbreeding between two singles’ could be useful system for bioreactor.