Prion strain discrimination using luminescent conjugated polymers.
ABSTRACT The occurrence of multiple strains of prions may reflect conformational variability of PrP(Sc), a disease-associated, aggregated variant of the cellular prion protein, PrP(C). Here we used luminescent conjugated polymers (LCPs), which emit conformation-dependent fluorescence spectra, for characterizing prion strains. LCP reactivity and emission spectra of brain sections discriminated among four immunohistochemically indistinguishable, serially mouse-passaged prion strains derived from sheep scrapie, chronic wasting disease (CWD), bovine spongiform encephalopathy (BSE), and mouse-adapted Rocky Mountain Laboratory scrapie prions. Furthermore, using LCPs we differentiated between field isolates of BSE and bovine amyloidotic spongiform encephalopathy, and identified noncongophilic deposits in prion-infected deer and sheep. We found that fibrils with distinct morphologies generated from chemically identical recombinant PrP yielded unique LCP spectra, suggesting that spectral characteristic differences resulted from distinct supramolecular PrP structures. LCPs may help to detect structural differences among discrete protein aggregates and to link protein conformational features with disease phenotypes.
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ABSTRACT: Abstract Fluorescent compounds capable of staining cells selectively without affecting their viability are gaining importance in biology and medicine. Recently, a new family of optical dyes, denoted luminescent conjugated oligothiophenes (LCOs), has emerged as an interesting class of highly emissive molecules for studying various biological phenomena. Properly functionalized LCOs have been utilized for selective identification of disease-associated protein aggregates and for selective detection of distinct cells. Herein, we present data on differential staining of various cell types, including cancer cells. The differential staining observed with newly developed pentameric LCOs is attributed to distinct side chain functionalities along the thiophene backbone. Employing flow cytometry and fluorescence microscopy we examined a library of LCOs for stainability of a variety of cell lines. Among tested dyes we found promising candidates that showed strong or moderate capability to stain cells to different extent, depending on target cells. Hence, LCOs with diverse imidazole motifs along the thiophene backbone were identified as an interesting class of agents for staining of cancer cells, whereas LCOs with other amino acid side chains along the backbone showed a complete lack of staining for the cells included in the study. Furthermore, for p-HTMI,a LCO functionalized with methylated imidazole moieties, the staining was dependent on the p53 status of the cells, indicating that the molecular target for the dye is a cellular component regulated by p53. We foresee that functionalized LCOs will serve as a new class of optical ligands for fluorescent classification of cells and expand the toolbox of reagents for fluorescent live imaging of different cells. © 2014 International Society for Advancement of Cytometry.Cytometry Part A 02/2014; · 3.71 Impact Factor
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ABSTRACT: Alzheimer's disease (AD) is associated with the deposition of β-amyloid (Aβ) plaques in the brain. In this issue, by cleverly processing patient samples, Lu et al. define a novel structural model of Aβ fibrils from AD brain, revealing surprising differences from in vitro fibrils. These findings may lead to structure-specific inhibitors and more selective amyloid-imaging methods.Cell 09/2013; 154(6):1182-4. · 31.96 Impact Factor
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ABSTRACT: Prion diseases are a group of fatal neurodegenerative diseases caused by the misfolding of cellular prion protein (PrPC) into pathogenic conformers (PrPSc). Although no effective therapies for prion diseases are currently available, a number of small molecule inhibitors have been identified that are capable of reducing or eliminating PrPSc in prion infected cells. However, recent experiments have shown that upon sustained treatment, prions have the capacity to evolve into drug resistant conformations. These studies suggest that the mechanism of prion strain adaptation involves rare conformational conversions followed by competitive selection among the heterogeneous pool of PrPSc conformers. The plasticity of prion conformers makes PrPSc a particularly challenging drug target and suggests that combination drug therapies or targeting of PrPC may be required for effective therapy. In this review, we highlight recent literature that demonstrate the phenomenon of prion drug resistance and strain specificity, and discuss potential ramifications for therapeutic efforts against prion diseases.Current topics in medicinal chemistry 09/2013; · 4.47 Impact Factor