Immunohistochemical characterization of transgenic mice highly expressing human lysosomal α-galactosidase

Abstract

Human lysosomal α-galactosidase predominantly hydrolyzes ceramide trihexoside. A transgenic mouse line, C57BL/6CrSIc–TgN(GLA) 1951 Rin, highly expressing human α-galactosidase, has been established and investigated biochemically and immunohistochemically in order to clarify the distribution of the expressed enzyme proteins and to evaluate it as a donor model of organ transplantation therapy for Fabry disease caused by a genetic defect of α-galactosidase. In these transgenic mice, about five copies of the transgene were integrated, and α-galactosidase activity was expressed in liver, kidney, heart, spleen, small intestine, submaxillary gland, skeletal muscle, cerebrum, cerebellum, bone marrow cells and serum. The enzyme activity was about 22 to 11,080-fold higher than that in non-transgenic mice. In liver, heart and kidney tissues, which are important organs for transplantation studies, sufficient amounts of α-galactosidase mRNAs were transcribed, and the expressed enzymes, with molecular weights of 54–60 kDa, are abundant in the liver (enzyme activity: 53,965 nmol h −1 mg −1 protein) and heart (39,906 nmol h −1 mg −1 protein), followed by in the kidney tissue (9177 nmol h −1 mg −1 protein), respectively. An immunohistochemical microscopic study clearly demonstrated the distribution of the expressed enzyme proteins in kidney and liver tissues. Highly expressed α-galactosidase was detected in glomerular cells, tubular cells and hepatocytes. These transgenic mice will be useful as a donor model for experimental organ transplantation, and also it will enable recurrent biopsies and long-term observation. The organ transplantation data on mice will provide us with important information.