Quantitative and qualitative analysis of cellular prion protein (PrPC) expression in bovine somatic tissues

The host encoded cellular prion protein (PrPC) is an N-linked glycoprotein tethered to the cell membrane by a glycophosphatidylinositol (GPI) anchor. Under certain conditions, PrPC can undergo conversion into a conformationally-altered isoform (PrPC) widely believed to be the pathogenic agent of transmissible spongiform encephalopathies (TSEs). Understanding the tissue-specific expression of PrPC is crucial considering that cells expressing high levels of PrPC bear a risk for conversion and accumulation of PrPC. In the present study, fifteen bovine somatic tissues were analyzed for PrPC expression by quantitative western blot and immunohistochemistry. Quantitative western blot analysis revealed highest expression of PrPC in cerebellum, obex and spinal cord. Intermediate levels were detected in thymus, intestine, nerve, heart and spleen, and lower levels in lung, muscle, kidney, lymph node, skin, pancreas and liver. Immunohistochemical analysis detected intense cellular-specific PrPC staining in neurons, thymocytes and lymphocytes. PrPC was also detected in the enteric wall, pancreatic islets of langerhans, myocardium, pulmonary alveolar sacs, renal glomeruli and dermal epithelial cells. This study demonstrated the quantitatively varied, wide-spread, tissue- and cell-specific expression pattern of PrPC in bovine somatic tissues. The importance of this study is to lay the foundation for understanding the tissue- specific expression of PrPC and to consider the potential participation of more bovine tissues in the transmission of BSE infection.