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Detection of prion protein mRNA in normal and scrapie-infected tissues and cell lines
B Caughey1, R E Race, B Chesebro
1National Institute of Allergy and Infectious Diseases, Rocky Mountain Laboratories, Hamilton, Montana 59840.
Abstract:
Prion protein (PrP) forms the fibrils or prion rods isolated from scrapie-infected brain and has been proposed as the major component of the infectious agent of this slowly progressive spongiform encephalopathy. In previous Northern blot analyses PrP-specific mRNAs have been found in both normal and scrapie-infected brains but not in spleen, an organ which harbours large titres of infectivity. In the present study, mouse PrP DNA was used to probe for PrP mRNA in assorted tissues and cells. A reexamination of mouse and hamster spleens revealed that they contained low levels of PrP mRNA (approx. 0.8% of that in brain mRNA). No consistent differences were observed between normal and scrapie-infected tissues. Also positive for PrP mRNA under stringent hybridization conditions were mouse epithelial, neuroblastoma, erythroid, B-lymphocytic and embryo fibroblast tissue culture cell lines, a hamster ovary cell line, a rat glioma cell line, and human T lymphocytic and neuroblastoma cell lines. In contrast, no PrP mRNA was detected in two mouse myeloid cell lines and one T cell lymphoma. These results provide evidence that PrP is a protein common to numerous, but not all, cell types besides those of the brain.
Insights
Prion protein (PrP) mRNA is present in various cell types beyond the brain, including spleen cells. This study found PrP mRNA in numerous cell lines, not just nervous tissue.
Area of Science:
- Neuroscience
- Molecular Biology
- Biochemistry
Background:
- Prion protein (PrP) is implicated as the infectious agent in scrapie, a spongiform encephalopathy.
- Previous studies indicated PrP mRNA absence in spleen, despite high infectivity levels.
Purpose of the Study:
- To investigate the presence and distribution of prion protein (PrP) mRNA in various tissues and cell types.
- To re-evaluate PrP mRNA levels in spleen and assess its presence in diverse cell lines.
Main Methods:
- Northern blot analysis using mouse PrP DNA as a probe.
- Hybridization under stringent conditions to detect PrP mRNA in assorted tissues and cell lines.
Main Results:
- Low levels of PrP mRNA were detected in mouse and hamster spleens (approx. 0.8% of brain levels).
- PrP mRNA was found in multiple cell lines, including epithelial, neuroblastoma, erythroid, B-lymphocytic, embryo fibroblast, ovary, and glioma cells.
- No PrP mRNA was detected in specific myeloid and T cell lymphoma lines.
Conclusions:
- Prion protein (PrP) is expressed in a wide range of cell types, not exclusively in brain tissue.
- The presence of PrP mRNA in spleen suggests a broader role for PrP beyond the central nervous system.