| 1. |
- Nordeman, Patrik, et al.
(author)
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C-11 and F-18 Radiolabeling of Tetra- and Pentathiophenes as PET-Ligands for Amyloid Protein Aggregates
- 2016
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In: ACS Medicinal Chemistry Letters. - : American Chemical Society (ACS). - 1948-5875 .- 1948-5875. ; 7:4, s. 368-373
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Journal article (peer-reviewed)abstract
- Three oligothiophenes were evaluated as PET ligands for the study of local and systemic amyloidosis ex vivo using tissue from patients with amyloid deposits and in vivo using healthy animals and PET-CT. The ex vivo binding studies revealed that all three labeled compounds bound specifically to human amyloid deposits. Specific binding was found in the heart, kidney, liver, and spleen. To verify the specificity of the oligothiophenes toward amyloid deposits, tissue sections with amyloid pathology were stained using the fluorescence exhibited by the compounds and evaluated with multiphoton microscopy. Furthermore, a in vivo monkey PET-CT study showed very low uptake in the brain, pancreas, and heart of the healthy animal indicating low nonspecific binding to healthy tissue. The biological evaluations indicated that this is a promising group of compounds for the visualization of systemic and localized amyloidosis.
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| 2. |
- Sjölander, Daniel, et al.
(author)
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Establishing the fluorescent amyloid ligand h-FTAA for studying human tissues with systemic and localized amyloid
- 2016
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In: Amyloid. - : Informa UK Limited. - 1350-6129 .- 1744-2818. ; 23:2, s. 98-108
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Journal article (peer-reviewed)abstract
- Rapid and accurate detection of amyloid deposits in routine surgical pathology settings are of great importance. The use of fluorescence microscopy in combination with appropriate amyloid specific dyes is very promising in this regard. Here we report that a luminescent conjugated oligothiophene, h-FTAA, rapidly and with high sensitivity and selectivity detects amyloid deposits in verified clinical samples from systemic amyloidosis patients with AA, AL and ATTR types; as well as in tissues laden with localized amyloidosis of AANF, AIAPP and ASem1 type. The probe h-FTAA emitted yellow red fluorescence on binding to amyloid deposits, whereas no apparent staining was observed in surrounding tissue. The only functional structure stained with h-FTAA showing the amyloidotypic fluorescence spectrum was Paneth cell granules in intestine. Screening of 114 amyloid containing tissues derived from 107 verified (Congo red birefringence and/or immunohistochemistry) amyloidosis patients revealed complete correlation between h-FTAA and Congo red fluorescence (107/107, 100% sensitivity). The majority of Congo red negative control cases (27 of 32, 85% specificity) were negative with h-FTAA. Small Congo red negative aggregates in kidney, liver, pancreas and duodenum were found by h-FTAA fluorescence in five control patients aged 72-83 years suffering from diverse diseases. The clinical significance of these false-positive lesions is currently not known. Because h-FTAA fluorescence is one magnitude brighter than Congo red and as the staining is performed four magnitudes lower than the concentration of dye, we believe that these inclusions are beyond detection by Congo red. We conclude that h-FTAA is a fluorescent hypersensitive, rapid and powerful tool for identifying amyloid deposits in tissue sections. Use of h-FTAA can be exploited as a rapid complementary technique for accurate detection of amyloid in routine surgical pathology settings. Our results also implicate the potential of the technique for detection of prodromal amyloidosis as well as for discovery of new amyloid-like protein aggregates in humans.
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| 3. |
- Babu Moparthi, Satish, et al.
(author)
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Differential conformational modulations of MreB folding upon interactions with GroEL/ES and TRiC chaperonin components
- 2016
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In: Scientific Reports. - : NATURE PUBLISHING GROUP. - 2045-2322. ; 6:28386
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Journal article (peer-reviewed)abstract
- Here, we study and compare the mechanisms of action of the GroEL/GroES and the TRiC chaperonin systems on MreB client protein variants extracted from E. coli. MreB is a homologue to actin in prokaryotes. Single-molecule fluorescence correlation spectroscopy (FCS) and time-resolved fluorescence polarization anisotropy report the binding interaction of folding MreB with GroEL, GroES and TRiC. Fluorescence resonance energy transfer (FRET) measurements on MreB variants quantified molecular distance changes occurring during conformational rearrangements within folding MreB bound to chaperonins. We observed that the MreB structure is rearranged by a binding-induced expansion mechanism in TRiC, GroEL and GroES. These results are quantitatively comparable to the structural rearrangements found during the interaction of beta-actin with GroEL and TRiC, indicating that the mechanism of chaperonins is conserved during evolution. The chaperonin-bound MreB is also significantly compacted after addition of AMP-PNP for both the GroEL/ES and TRiC systems. Most importantly, our results showed that GroES may act as an unfoldase by inducing a dramatic initial expansion of MreB (even more than for GroEL) implicating a role for MreB folding, allowing us to suggest a delivery mechanism for GroES to GroEL in prokaryotes.
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| 4. |
- Bednarska, Natalia G., et al.
(author)
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Protein aggregation as an antibiotic design strategy
- 2016
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In: Molecular Microbiology. - : WILEY-BLACKWELL. - 0950-382X .- 1365-2958. ; 99:5, s. 849-865
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Journal article (peer-reviewed)abstract
- Taking advantage of the xenobiotic nature of bacterial infections, we tested whether the cytotoxicity of protein aggregation can be targeted to bacterial pathogens without affecting their mammalian hosts. In particular, we examined if peptides encoding aggregation-prone sequence segments of bacterial proteins can display antimicrobial activity by initiating toxic protein aggregation in bacteria, but not in mammalian cells. Unbiased in vitro screening of aggregating peptide sequences from bacterial genomes lead to the identification of several peptides that are strongly bactericidal against methicillin-resistant Staphylococcus aureus. Upon parenteral administration in vivo, the peptides cured mice from bacterial sepsis without apparent toxic side effects as judged from histological and hematological evaluation. We found that the peptides enter and accumulate in the bacterial cytosol where they cause aggregation of bacterial polypeptides. Although the precise chain of events that leads to cell death remains to be elucidated, the ability to tap into aggregation-prone sequences of bacterial proteomes to elicit antimicrobial activity represents a rich and unexplored chemical space to be mined in search of novel therapeutic strategies to fight infectious diseases.
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| 5. |
- Brydsten, Anna, et al.
(author)
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Does contextual unemployment matter for health status across the life course?
- 2016
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In: European Journal of Public Health. - : Oxford University Press. - 1101-1262 .- 1464-360X. ; 26:Suppl 1, s. 142-142
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Journal article (peer-reviewed)abstract
- Background: Individual health is affected by one’s individual life conditionsand by the context in which individuals live, interact anddevelop. Research shows that living in a neighbourhood withhigh levels of unemployment might affect residents’ health, atleast partially independent of own labour market status.However, how such contextual-individual transactions playout across the life course is unknown. The present study aims:(i) to examine whether neighbourhood unemployment isrelated to health status across the life course independently ofthe individual employment from adolescence to middle age(age 16 to 42); and (ii) to analyse whether this relationship isobservable at four specific life course periods from adolescenceto middle age (age 16, 21, 30 and 42).Methods: A 26-year prospective Swedish cohort (n = 1010), linked toregister data on neighbourhood unemployment. Individualemployment and functional somatic symptoms were measuredby self-reported questionnaire data. Two models of hierarchallinear regressions were built: a longitudinal analysis, and a setof age-specific cross-sectional analyses at each age.Results: The longitudinal analysis showed an independent contributionof neighbourhood unemployment and individual employmenton FSS across the life course. The cross-sectional analysisshowed an association at age 30, when accounting forindividual employment, but no association was found at age21 and 42.Conclusions: Neighbourhood unemployment has a significant relationshipwith functional somatic symptoms across the life course. Thereseems to be an age-specific pattern where neighbourhoodunemployment may have stronger implications in earlyadulthood than in other phases of the life courseKey messages:High neighbourhood unemployment predicts higher levelsof individual FSS across the life course, independently ofown labour market position, socioeconomic status andeducationThese findings stress the importance of neighbourhoodunemployment for current health status as well as development of health status across the life course, particular duringearly adulthood
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| 6. |
- Campos Melo, Raúl Ivan, et al.
(author)
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Novel Trans-Stilbene-based Fluorophores as Probes for Spectral Discrimination of Native and Protofibrillar Transthyretin
- 2016
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In: ACS Chemical Neuroscience. - : American Chemical Society (ACS). - 1948-7193. ; 7:7, s. 924-940
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Journal article (peer-reviewed)abstract
- Accumulation of misfolded transthyretin (TTR) as amyloid fibrils causes various human disorders. Native transthyretin is a neurotrophic protein and is a putative extracellular molecular chaperone. Several fluorophores have been shown in vitro to bind selectively to native TTR. Other compounds, such as thioflavin T, bind TTR amyloid fibrils. The probe 1-anilinonaphthalene-8-sulfonate (ANS) binds to both native and fibrillar TTR, becoming highly fluorescent, but with indistinguishable emission spectra for native and fibrillar TTR. Herein we report our efforts to develop a fluorescent small molecule capable of binding both native and misfolded protofibrillar TTR, providing distinguishable emission spectra. We used microwave synthesis for efficient production of a small library of trans-stilbenes and fluorescence spectral screening of their binding properties. We synthesized and tested 22 trans-stilbenes displaying a variety of functional groups. We successfully developed two naphthyl-based trans-stilbenes probes that detect both TTR states at physiological concentrations. The compounds bound with nanomolar to micromolar affinities and displayed distinct emission maxima upon binding native or misfolded protofibrillar TTR (>100 nm difference). The probes were mainly responsive to environment polarity providing evidence for the divergent hydrophobic structure of the binding sites of these protein conformational states. Furthermore, we were able to successfully use one of these probes to quantify the relative amounts of native and protofibrillar TTR in a dynamic equilibrium. In conclusion, we identified two trans-stilbene-based fluorescent probes, (E)-4-(2-(naphthalen-1-yl)vinyl)benzene-1,2-diol (11) and (E)-4-(2-(naphthalen-2-yl)vinyl)benzene-1,2-diol (14), that bind native and protofibrillar TTR, providing a wide difference in emission maxima allowing conformational discrimination by fluorescence spectroscopy. We expect these novel molecules to serve as important chemical biology research tools in studies of TTR folding and misfolding.
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| 7. |
- Gabrielsson, Erik, et al.
(author)
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Spatiotemporal Control of Amyloid-Like A Plaque Formation Using a Multichannel Organic Electronic Device
- 2016
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In: Macromolecular materials and engineering. - : WILEY-V C H VERLAG GMBH. - 1438-7492 .- 1439-2054. ; 301:4, s. 359-363
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Journal article (peer-reviewed)abstract
- We herein report on an iontronic device to drive and control A1-40 and A1-42 fibril formation. This system allows kinetic control of A aggregation by regulation of H+ flows. The formed aggregates show both nanometer-sized fibril structure and microscopic growth, thus mimicking senile plaques, at the H+-outlet. Mechanistically we observed initial accumulation of A1-40 likely driven by electrophoretic migration which preceded nucleation of amyloid structures in the accumulated peptide cluster.
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| 8. |
- Gallardo, Rodrigo, et al.
(author)
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De novo design of a biologically active amyloid
- 2016
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In: Science. - : AMER ASSOC ADVANCEMENT SCIENCE. - 0036-8075 .- 1095-9203. ; 354:6313, s. 720-
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Journal article (peer-reviewed)abstract
- Most human proteins possess amyloidogenic segments, but only about 30 are associated with amyloid-associated pathologies, and it remains unclear what determines amyloid toxicity. We designed vascin, a synthetic amyloid peptide, based on an amyloidogenic fragment of vascular endothelial growth factor receptor 2 (VEGFR2), a protein that is not associated to amyloidosis. Vascin recapitulates key biophysical and biochemical characteristics of natural amyloids, penetrates cells, and seeds the aggregation of VEGFR2 through direct interaction. We found that amyloid toxicity is observed only in cells that both express VEGFR2 and are dependent on VEGFR2 activity for survival. Thus, amyloid toxicity here appears to be both protein-specific and conditional-determined by VEGFR2 loss of function in a biological context in which target protein function is essential.
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| 9. |
- Hammarström, Lars G. J., et al.
(author)
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The Oncolytic Efficacy and in Vivo Pharmacokinetics of [2-(4-Chlorophenyl)quinolin-4-yl](piperidine-2-yl)methanol (Vacquinol-1) Are Governed by Distinct Stereochemical Features
- 2016
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In: Journal of Medicinal Chemistry. - : American Chemical Society (ACS). - 0022-2623 .- 1520-4804. ; 59:18, s. 8577-8592
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Journal article (peer-reviewed)abstract
- Glioblastoma remains an incurable brain cancer. Drugs developed in the past 20 years have not improved the prognosis for patients, necessitating the development of new treatments. We have previously reported the therapeutic potential of the quinoline methanol Vacquinol-1 (1) that targets glioblastoma cells and induces cell death by catastrophic vacuolization. Compound 1 is a mixture of four stereoisomers due to the two adjacent stereogenic centers in the molecule, complicating further development in the preclinical setting. This work describes the isolation and characterization of the individual isomers of 1 and shows that these display stereospecific pharmacokinetic and pharmacodynamic features. In addition, we present a stereoselective synthesis of the active isomers, providing a basis for further development of this compound series into a novel experimental therapeutic for glioblastoma.
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| 10. |
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