PrP mRNA and protein expression in brain and PrPc in CSF in Creutzfeldt-Jakob disease MM1 and VV2

Creutzfeldt-Jakob disease (CJD) is a heterogenic neurodegenerative disorder associated with abnormal post-translational processing of cellular prion protein (PrPc). CJD displays distinctive clinical and pathological features which correlate with the genotype at the codon 129 (methionine or valine: M or V respectively) in the prion protein gene and with size of the protease-resistant core of the abnormal prion protein PrPsc (type 1: 20/21 kDa and type 2: 19 kDa). MM1 and VV2 are the most common sporadic CJD (sCJD) subtypes. PrP mRNA expression levels in the frontal cortex and cerebellum are reduced in sCJD in a form subtype-dependent. Total PrP protein levels and PrPsc levels in the frontal cortex and cerebellum accumulate differentially in sCJD MM1 and sCJD VV2 with no relation between PrPsc deposition and spongiform degeneration and neuron loss, but with microgliosis, and IL6 and TNF- response. In the CSF, reduced PrPc, the only form present in this compartment, occurs in sCJD MM1 and VV2. PrP mRNA expression is also reduced in the frontal cortex in advanced stages of Alzheimer disease, Lewy body disease, progressive supranuclear palsy, and frontotemporal lobe degeneration, but PrPc levels in brain varies from one disease to another. Reduced PrPc levels in CSF correlate with PrP mRNA expression in brain, which in turn reflects severity of degeneration in sCJD.