Protein expression of nuclear receptors in human and murine tissues.

Nuclear receptors (NR) are transcriptional regulators expressed in a variety of tissues and they play important roles in embryonic development, organogenesis and metabolic homeostasis. In order to investigate the tissue-specific expression pattern of NR, mouse anti-human monoclonal antibodies newly generated against various NR. Specificities of the antibodies were confirmed on immunoblotting using overexpressed proteins. Most of the antibodies recognized intrinsic protein. Among 60 monoclonal antibodies generated, 32 were applicable for immunohistochemistry. The expression pattern of NR in human liver and pancreas was confirmed on immunohistochemical staining using these antibodies. The P2 promoter-driven hepatocyte nuclear factor 4alpha (HNF4alpha) isoform and progesterone receptor were expressed in pancreatic alpha-cells, but not beta-cells in the human pancreas, suggesting an unknown role of these NR in diabetes mellitus. These antibodies were also useful for immunohistochemistry of the murine liver and pancreas. Immunoblotting using these antibodies produced similar corresponding bands both in human and mouse tissues. These monoclonal antibodies may serve as powerful tools to detect tissue-specific localization of NR and provide a platform for future studies of NR in human and murine tissues.