Regional and phenotype heterogeneity of cellular prion proteins in the human brain

Abstract

Transmissible spongiform encephalopathies (TSEs) are neurological disorders that include genetic, infectious and sporadic forms of human Creutzfeldt-Jakob disease (CJD). The pathogenic agent is the prion protein that is composed of an abnormal isoform (PrP(Sc)) of a host-encoded protein (PrP(C)). Analysis of the relative amounts of PrP(Sc) glycoforms has been used to discriminate between various agents involved in TSE. The distribution and efficiency of conversion to PrP(Sc) can be influenced by differences in the expression of PrP(C). However, little attention has been given so far to the banding patterns of PrP(C). Using four different antibodies recognizing amino- and carboxyl-terminal PrP sequences we analysed the glycoforms of PrP(C) in seven regions of the human brain using brains obtained from six subjects. For determination of the staining intensities, signals were quantified by densitometry and reproducible patterns were accomplished by many repeated immunoblot analyses. When amino-terminal binding antibodies were used for detection, PrP(C) in the frontal neocortex, nucleus lentiformis, thalamus, hippocampus and cerebellum displayed a glycotype with high staining of the diglycosylated isoforms. This was different from patterns in the pons and medulla oblongata, which showed a high intensity of the nonglycosylated isoform, and PrP(C) proteins, approximately 27 kDa in size, exhibited high staining using the carboxyl-terminal binding antibodies. This intense staining followed from an overlay of full-length and truncated PrP(C) isoforms. Furthermore, we found marked differences in the expression of PrP(C). Variations in the processing of PrP(C) may lead to interregional differences in the glycoform composition of PrP(Sc) in human brains.

Glycosylation-related genes are variably expressed depending on the differentiation state of a bioaminergic neuronal cell line: implication for the cellular prion protein

“…Differential PrP C glycosylation has been documented in cell lines of different origins, but also in different organs, interestingly, depending on brain regions in mouse and human species [18,19,35,36]. Here we showed that an heterogeneity of PrP C glycopatterns was associated to bioaminergic differentiation programs.…”

Prion protein “gamma-cleavage”: characterizing a novel endoproteolytic processing event

“…One explanation may be that c-cleavage does not occur in cells of the brain region we sampled from, as cleavage profiles have been shown to vary in different tissues and regions [69]. Alternatively, C3 may be below the limits of detection by PAGE and western blotting.…”

“…Despite this, the biological or physiological significance of PrP C proteolytic processing has not been entirely elucidated, with emerging, but sometimes conflicting evidence of separate functions of the full length [14,64,65], and different truncated PrP C species [6,10,[66][67][68]. Importantly, there are often more truncated PrP C species than full-length PrP C present in cells and tissues [33,35,69], underscoring the likely cellular requirement for these processes to occur. Through the utilization of Myc-tagged PrP C expressed in cells we discovered a novel, approximately 6-7 kDa, Myc-tagged 'C3' fragment, and then confirmed the presence of endogenous C3 in both human and animal brain tissue, indicating the fragment was not produced as an Extensive literature searching has found that the most commonly utilized antiPrP antibodies are directed to epitopes in the middle region of PrP C , and unlikely to be within the C3 fragment.…”

The Biological Function of the Prion Protein: A Cell Surface Scaffold of Signaling Modules

“…Distinct patterns of sialylation have also been described for PrP C from either brain or spleen (Baskakov and Katorcha, 2016), and possible roles of sialylation upon functional properties of PrP C were discussed (Baskakov and Katorcha, 2016). Other studies indicated that posttranslational modifications produce a collection of differing glycosylated forms of PrP C (Pan et al, 2002), which vary across distinct brain regions (Kuczius et al, 2007b) and change with aging (Goh et al, 2007). Heterogeneous glycosylation is likely to impart selectivity of ligand binding, as suggested both by differential binding to antibodies (Li et al, 2001; Kuczius et al, 2007a) and metal ions (Moudjou et al, 2007), as well as by the differing outcomes of peripheral inoculation of TSE upon experimental prion disease in mice expressing distinct glycosylated forms of PrP C (Cancellotti et al, 2010).…”