%0 Journal Article %J J Alzheimers Dis %D 2016 %T Prion Protein-Hemin Interaction Upregulates Hemoglobin Synthesis: Implications for Cerebral Hemorrhage and Sporadic Creutzfeldt-Jakob Disease. %A Tripathi, Ajai K %A Singh, Neena %K Animals %K Brain %K Cell Line, Tumor %K Creutzfeldt-Jakob Syndrome %K Endocytosis %K Ferritins %K Green Fluorescent Proteins %K Hemin %K Hemoglobins %K Humans %K In Vitro Techniques %K Leukemia, Erythroblastic, Acute %K Mice %K Mice, Transgenic %K Neuroblastoma %K Neuroglia %K Neurons %K Organ Culture Techniques %K Prion Proteins %K Transfection %K Up-Regulation %X

Hemin is known to induce endocytosis of prion-protein (PrP(C)) from the neuronal plasma membrane, potentially limiting propagation of the disease causing PrP-scrapie (PrP(Sc)) isoform. Hemin is therefore an attractive disease-modifying option for sporadic Creutzfeldt-Jakob disease (sCJD), a human prion disorder with no effective treatment. The hemin-PrP(C) interaction is also of interest in cerebral-hemorrhage (CH), a condition where potentially toxic hemin molecules come in contact with neuronal PrP(C). Interestingly, PrP(C) is upregulated in penumbric neurons surrounding CH and is known to confer neuroprotection in a dose-dependent manner. The underlying mechanism, however, is not clear. Here, we report that hemin binds PrP(C) on diverse cell lines, resulting in its aggregation or degradation in a cell-type specific manner. Surprisingly, the hemin-PrP(C) interaction upregulates Hb synthesis in hematopoietic cells, a response reversed by deleting the hemin-binding octa-peptide repeat region of PrP(C). A similar response is noted in brain organotypic cultures where exposure to hemin induces significantly more α-globin in wild-type (PrP(+/+)) relative to PrP-knock-out (PrP(-/-)) samples. Furthermore, red blood cells and brain tissue from PrP(-/-) mice show significantly less α-globin relative to PrP(+/+) controls, indicating a positive effect of PrP(C) on Hb synthesis under physiological conditions as well. Surprisingly, levels of α-globin are significantly higher in sCJD brain tissue relative to controls, suggesting compensatory upregulation of Hb synthesis by surviving neurons or misregulation in diseased brains. These observations reveal a unique function of PrP(C) that is likely to impact the therapeutic management of CH and sCJD.

%B J Alzheimers Dis %V 51 %P 107-21 %8 2016 %G eng %N 1 %1 http://www.ncbi.nlm.nih.gov/pubmed/26836195?dopt=Abstract %R 10.3233/JAD-151039