Endogenous Human Proteins Interfering with Amyloid Formation.

Amyloid formation is a pathological process associated with a wide range of degenerative disorders, including Alzheimer's disease, Parkinson's disease, and diabetes mellitus type 2. During disease progression, abnormal accumulation and deposition of proteinaceous material are accompanied by tissue degradation, inflammation, and dysfunction. Agents that can interfere with the process of amyloid formation or target already formed amyloid assemblies are consequently of therapeutic interest.

Tandem Ring Opening/Intramolecular [2 + 2] Cycloaddition Reaction for the Synthesis of Cyclobutane Fused Thiazolino-2-Pyridones.

Reaction of thiazoline fused 2-pyridones with alkyl halides in the presence of cesium carbonate opens the thiazoline ring via -alkylation and generates -alkenyl functionalized 2-pyridones. In the reaction with propargyl bromide, the thiazoline ring opens and subsequently closes via a [2 + 2] cycloaddition between an generated allene and the α,β-unsaturated methyl ester. This method enabled the synthesis of a variety of cyclobutane fused thiazolino-2-pyridones, of which a few analogues inhibit amyloid β fibril formation.

KSO-mediated coupling of 6-amino-7-aminomethyl-thiazolino-pyridones with aldehydes to construct amyloid affecting pyrimidine-fused thiazolino-2-pyridones.

We herein present the synthesis of diversely functionalized pyrimidine fused thiazolino-2-pyridones KSO-mediated oxidative coupling of 6-amino-7-(aminomethyl)-thiazolino-2-pyridones with aldehydes. The developed protocol is mild, has wide substrate scope, and does not require transition metal catalyst or base. Some of the synthesized compounds have an ability to inhibit the formation of Amyloid-β fibrils associated with Alzheimer's disease, while others bind to mature amyloid-β and α-synuclein fibrils.

Mechanisms of Transthyretin Inhibition of IAPP Amyloid Formation.

Amyloid-formation by the islet amyloid polypeptide (IAPP), produced by the β-cells in the human pancreas, has been associated with the development of type II diabetes mellitus (T2DM). The human plasma-protein transthyretin (TTR), a well-known amyloid-inhibiting protein, is interestingly also expressed within the IAPP producing β-cells. In the present study, we have characterized the ability of TTR to interfere with IAPP amyloid-formation, both in terms of its intrinsic stability as well as with regard to the effect of TTR-stabilizing drugs.

Intramolecular Povarov Reactions for the Synthesis of Chromenopyridine Fused 2-Pyridone Polyheterocycles Binding to α-Synuclein and Amyloid-β Fibrils.

A BF·OEt catalyzed intramolecular Povarov reaction was used to synthesize 15 chromenopyridine fused thiazolino-2-pyridone peptidomimetics. The reaction works with several -alkylated salicylaldehydes and amino functionalized thiazolino-2-pyridones, to generate polyheterocycles with diverse substitution. The synthesized compounds were screened for their ability to bind α-synuclein and amyloid β fibrils .

Apolipoprotein E Interferes with IAPP Aggregation and Protects Pericytes from IAPP-Induced Toxicity.

Apolipoprotein E (ApoE) has become a primary focus of research after the discovery of its strong linkage to Alzheimer's disease (AD), where the ApoE4 variant is the highest genetic risk factor for this disease. ApoE is commonly found in amyloid deposits of different origins, and its interaction with amyloid-β peptide (Aβ), the hallmark of AD, is well known. However, studies on the interaction of ApoEs with other amyloid-forming proteins are limited.

Morphological analysis of Apolipoprotein E binding to Aβ Amyloid using a combination of Surface Plasmon Resonance, Immunogold Labeling and Scanning Electron Microscopy.

Background: Immunogold labeling in combination with transmission electron microscopy analysis is a technique frequently used to correlate high-resolution morphology studies with detailed information regarding localization of specific antigens. Although powerful, the methodology has limitations and it is frequently difficult to acquire a stringent system where unspecific low-affinity interactions are removed prior to analysis.

Results: We here describe a combinatorial strategy where surface plasmon resonance and immunogold labeling are used followed by a direct analysis of the sensor-chip surface by scanning electron microscopy.

Apolipoprotein E impairs amyloid-β fibril elongation and maturation.

Alzheimer's disease (AD) is strongly linked to amyloid depositions of the Aβ peptide (Aβ). The lipid-binding protein apolipoprotein E (ApoE) has been found to interfere with Aβ amyloid formation and to exert a strong clinical impact to the pathology of AD. The APOE gene exists in three allelic isoforms represented by APOE ε2, APOE ε3, and APOE ε4.

Similarities in Blood Mononuclear Cell Membrane Phospholipid Profiles During Malignancy.

Phospholipids (PLs), key elements of cellular membranes, are regulated reciprocally with membrane proteins and can act as sensors for alterations in physiological or pathological states of cells including initiation and development of cancer. On the other hand, peripheral blood mononuclear cells (MNCs) play an important role in antitumor immune response by reacting to cancerous modifications in distant organs. In the current study, we tested the hypothesis that tumor initiation and development are reflected in the alteration pattern of the MNC PL component.

Scanning electron microscopy as a tool for evaluating morphology of amyloid structures formed on surface plasmon resonance chips.

We demonstrate the use of Scanning Electron microscopy (SEM) in combination with Surface Plasmon Resonance (SPR) to probe and verify the formation of amyloid and its morphology on an SPR chip. SPR is a technique that measures changes in the immobilized weight on the chip surface and is frequently used to probe the formation and biophysical properties of amyloid structures. In this context it is of interest to also monitor the morphology of the formed structures.

Transthyretin Interferes with Aβ Amyloid Formation by Redirecting Oligomeric Nuclei into Non-Amyloid Aggregates.

The pathological Aβ aggregates associated with Alzheimer's disease follow a nucleation-dependent path of formation. A nucleus represents an oligomeric assembly of Aβ peptides that acts as a template for subsequent incorporation of monomers to form a fibrillar structure. Nuclei can form de novo or via surface-catalyzed secondary nucleation, and the combined rates of elongation and nucleation control the overall rate of fibril formation.

The Properties of Amyloid-β Fibrils Are Determined by their Path of Formation.

Fibril formation of the amyloid-β peptide (Aβ) follows a nucleation-dependent polymerization process and is associated with Alzheimer's disease. Several different lengths of Aβ are observed in vivo, but Aβ1-40 and Aβ1-42 are the dominant forms. The fibril architectures of Aβ1-40 and Aβ1-42 differ and Aβ1-42 assemblies are generally considered more pathogenic.

Enthalpic Forces Correlate with the Selectivity of Transthyretin-Stabilizing Ligands in Human Plasma.

The plasma protein transthyretin (TTR) is linked to human amyloidosis. Dissociation of its native tetrameric assembly is a rate-limiting step in the conversion from a native structure into a pathological amyloidogenic fold. Binding of small molecule ligands within the thyroxine binding site of TTR can stabilize the tetrameric integrity and is a potential therapeutic approach.

A generic method for design of oligomer-specific antibodies.

Antibodies that preferentially and specifically target pathological oligomeric protein and peptide assemblies, as opposed to their monomeric and amyloid counterparts, provide therapeutic and diagnostic opportunities for protein misfolding diseases. Unfortunately, the molecular properties associated with oligomer-specific antibodies are not well understood, and this limits targeted design and development. We present here a generic method that enables the design and optimisation of oligomer-specific antibodies.

The role of pro-inflammatory S100A9 in Alzheimer's disease amyloid-neuroinflammatory cascade.

Pro-inflammatory S100A9 protein is increasingly recognized as an important contributor to inflammation-related neurodegeneration. Here, we provide insights into S100A9 specific mechanisms of action in Alzheimer's disease (AD). Due to its inherent amyloidogenicity S100A9 contributes to amyloid plaque formation together with Aβ.

S100A8/A9 amyloidosis in the ageing prostate: relating ex vivo and in vitro studies.

The family of S100 proteins encompasses more than 20 members characterized by remarkable conformational and functional diversity. S100 proteins act as central regulators of various cellular processes, including cell survival, proliferation, differentiation, and motility. Many S100 proteins are implicated in various types of cancer as well as neurodegenerative, inflammatory, and autoimmune diseases.

Pro-inflammatory S100A8 and S100A9 proteins: self-assembly into multifunctional native and amyloid complexes.

S100A8 and S100A9 are EF-hand Ca(2+) binding proteins belonging to the S100 family. They are abundant in cytosol of phagocytes and play critical roles in numerous cellular processes such as motility and danger signaling by interacting and modulating the activity of target proteins. S100A8 and S100A9 expression levels increased in many types of cancer, neurodegenerative disorders, inflammatory and autoimmune diseases and they are implicated in the numerous disease pathologies.

Neuroprotective and nootropic drug noopept rescues α-synuclein amyloid cytotoxicity.

Parkinson's disease is a common neurodegenerative disorder characterized by α-synuclein (α-Syn)-containing Lewy body formation and selective loss of dopaminergic neurons in the substantia nigra. We have demonstrated the modulating effect of noopept, a novel proline-containing dipeptide drug with nootropic and neuroprotective properties, on α-Syn oligomerization and fibrillation by using thioflavin T fluorescence, far-UV CD, and atomic force microscopy techniques. Noopept does not bind to a sterically specific site in the α-Syn molecule as revealed by heteronuclear two-dimensional NMR analysis, but due to hydrophobic interactions with toxic amyloid oligomers, it prompts their rapid sequestration into larger fibrillar amyloid aggregates.

Lysozyme amyloid oligomers and fibrils induce cellular death via different apoptotic/necrotic pathways.

Among the newly discovered amyloid properties, its cytotoxicity plays a key role. Lysozyme is a ubiquitous protein involved in systemic amyloidoses in vivo and forming amyloid under destabilising conditions in vitro. We characterized both oligomers and fibrils of hen lysozyme by atomic force microscopy and demonstrated their dose (5-50 microM) and time-dependent (6-48 h) effect on neuroblastoma SH-SY5Y cell viability.

Mu opioid receptor A118G polymorphism in association with striatal opioid neuropeptide gene expression in heroin abusers.

Mu opioid receptors are critical for heroin dependence, and A118G SNP of the mu opioid receptor gene (OPRM1) has been linked with heroin abuse. In our population of European Caucasians (n = 118), approximately 90% of 118G allelic carriers were heroin users. Postmortem brain analyses showed the OPRM1 genotype associated with transcription, translation, and processing of the human striatal opioid neuropeptide system.

Cytotoxicity of albebetin oligomers depends on cross-beta-sheet formation.

Prefibrillar cytotoxicity was suggested as a common amyloid characteristic. We showed two types of albebetin prefibrillar oligomers are formed during incubation at pH 7.3.

Prodynorphin transcripts and proteins differentially expressed and regulated in the adult human brain.

Transcription from multiple promoters along with alternative mRNA splicing constitutes the basis for cell-specific gene expression and mRNA and protein diversity. The prodynorphin gene (PDYN) gives rise to prodynorphin (PDYN), precursor to dynorphin opioid peptides that regulate diverse physiological functions and are implicated in various neuropsychiatric disorders. Here, we characterized PDYN transcripts and proteins in the adult human brain and studied PDYN processing and intracellular localization in model cell lines.