Cellular Prion Proteins in Human Platelets Show a Phenotype Different to Those in Brain Tissues

Prion diseases are characterized by high accumulation of infectious prion proteins (PrPSc) in brains. PrPsc are propagated by the conversion of host-encoded cellular prion proteins (PrPC) which are essential for developing the disease but are heterogeneously expressed in brains. The disease can be transmitted to humans and animals through blood and blood products, however, little attention has been given to molecular characterization of PrPC in blood cells. In this presented study, we characterized phenotypically PrPC of platelets (pit) and characterized the proteins regarding their glycobanding profiles by quantitative immunoblotting using a panel of monoclonal antibodies. The glycosylation patterns of pit and brain PrPC were compared using the ratios of di-, mono-, and non-glycosylated prions. The detergent solubility of pit and brain PrPC was also analyzed. The distinct banding patterns and detergent solubility of pit PrPC differed clearly from the glycosylation profiles and solubility characteristics of brain PrPC. Plt PrPC exhibited single or only few prion protein types, whereas brain PrPC showed more extensive banding patterns and lower detergent solubility. Plt PrPC are post-translational modified differently from PrPC in brain. These findings suggest other or less physiological functions of pit PrPC than in brain. J. Cell. Biochem. 112: 954-962, 2011. (C) 2010 Wiley-Liss, Inc.