Prion protein gene expression in cultured cells

Area of Science:

• Molecular Biology
• Neuroscience
• Biochemistry

Background:

• The prion protein (PrP) exists in two isoforms: cellular (PrPC) and scrapie (PrPSc).
• PrPSc is associated with transmissible spongiform encephalopathies like scrapie.
• Understanding PrP expression is key to understanding these diseases.

Purpose of the Study:

• To investigate the expression levels of PrP in cultured cell lines.
• To determine if cell lines can be used to study PrP processing and function.
• To explore methods for achieving higher PrP expression in vitro.

Main Methods:

• Cultured cell lines were analyzed for endogenous PrP mRNA and protein levels.
• Transfection experiments using expression vectors with strong eukaryotic promoters were performed.
• High-level PrP expression was induced using baculovirus and SV40-based vectors.

Main Results:

• Cultured cells showed PrP mRNA levels comparable to rodent brains but significantly reduced PrP protein levels, often undetectable by Western immunoblot.
• Transfection with standard expression vectors did not lead to elevated PrP expression.
• High-level expression using baculovirus or SV40 vectors produced PrP, but with altered processing compared to brain PrPC.
• SV40 vector-expressed PrP showed cell surface transport, while baculovirus-expressed PrP did not induce scrapie in hamsters.

Conclusions:

• Cultured cell lines exhibit post-transcriptional regulation of PrP expression.
• Mammalian expression systems like the SV40 late promoter vector show promise for studying PrPSc roles and PrPC function.
• Further research is needed to fully understand PrP processing and its implications in prion diseases.