ABSTRACT
The prion properties of alpha-synuclein, a key aggregating protein involved in the pathogenesis of so-called synucleinopathies, including Parkinson's disease (PD), dementia with Lewy bodies, multiple system atrophy, and its various conformers are discussed. It is shown that alpha-synuclein may be transferred between cells by prion-like propagation. Similarly to other prions, alpha-synuclein aggregation develops from the initial lag-phase (nucleation) to the subsequent growth phase (elongation), and to the stationary phase where the aggregates and monomers exist in equilibrium. Similarly to prions, alpha-synuclein undergoes conformational changes from an alpha-helix to its beta-folded structure. However, there is currently no evidence that alpha-synuclein-dependent PD can be transmitted from person-to-person. This review describes the prion properties of alpha-synuclein, possible ways of its intercellular propagation, and novel approaches to PD diagnostics.
Subject(s)
Parkinson Disease/metabolism , Parkinson Disease/pathology , Prions/metabolism , Prions/pathogenicity , alpha-Synuclein/metabolism , Humans , Parkinson Disease/diagnosisABSTRACT
Deposits of amyloid peptide Aß and intracellular aggregates of hyperphosphorylated tau protein in the brain of patients are major neuropathological features of Alzheimer's disease (AD). For a long time, the possibility of horizontal transmission of Aß aggregates from cell to cell and from person to person remained hypothetical, since there was no experimental evidence. However, in 1993, the formation of senile plaques was confirmed in the brains of animals after intracerebral injections of AD patient brain homogenates or homogenates of the brain of transgenic mice enriched with Aß aggregates. Other experiments indicate that amyloid peptide Aß and intracellular aggregates of hyperphosphorylated tau protein may be transferred from cell to cell like prions. In 2015 and 2016, it was reported that AD could be transmitted to humans during medical procedures, i.e., that this disease might be iatrogenic. This review discusses the mechanisms by which pathogenic Aß protein can be transmitted between cells and analyzes the current evidence concerning the possibility of horizontal Aß transmission from person to person.
Subject(s)
Alzheimer Disease/genetics , Protein Aggregation, Pathological/genetics , tau Proteins/genetics , Alzheimer Disease/metabolism , Alzheimer Disease/pathology , Amyloid beta-Peptides/genetics , Amyloid beta-Peptides/metabolism , Animals , Brain/metabolism , Disease Models, Animal , Humans , Mice , Plaque, Amyloid/genetics , Plaque, Amyloid/pathology , tau Proteins/metabolismABSTRACT
Atherosclerosis is one of the most common causes of death worldwide. Epidemiology studies firmly established an inverse relationship between atherogenesis and distorted lipid metabolism, in particular, higher levels of total cholesterol, an accumulation of CH-laden macrophages (foam cells), and lower plasma levels of antiatherogenic high density lipoprotein (HDL). It is believed that the reverse cholesterol transport, a process that removes excess cholesterol from peripheral tissues/cells including macrophages to circulating HDL, is one of the main mechanisms responsible for anti-atherogenic properties of HDL. The key proteins of reverse cholesterol transport-ATP-binding cassette transporters A1 (ABCA1) and G1 (ABCG1)-mediate the cholesterol efflux from macrophages and prevent their transformation into foam cells. This review focuses on the role of ABC transporters A1 and G1 in the pathogenesis of atherosclerosis.
Subject(s)
ATP Binding Cassette Transporter 1/genetics , ATP-Binding Cassette Transporters/genetics , Atherosclerosis/genetics , Cholesterol/metabolism , ATP Binding Cassette Transporter 1/metabolism , ATP Binding Cassette Transporter, Subfamily G, Member 1 , ATP-Binding Cassette Transporters/metabolism , Atherosclerosis/metabolism , Atherosclerosis/pathology , Cholesterol/genetics , Humans , Kidney/metabolism , Lipid Metabolism , Lipoproteins, HDL , Macrophages/metabolismABSTRACT
Amyloid precursor protein (APP) is a key player in Alzheimer's disease. The proteolytic cleavage of APP results in various short peptide fragments including the toxic amyloid-beta peptide, which is a main component of senile plaques. However, the functions of APP and its processed fragments are not yet well understood. Here, using real-time polymerase chain reaction, we demonstrate that exogenous expression of APP, its mutant form APP-Swedish, or two truncated forms in Drosophila melanogaster causes a significant (P ≤ 0.05) drop in the mRNA levels of the presynaptic proteins synaptotagmin-1 and neuronal synaptobrevin. The results obtained from this study suggest a potential role of APP or its fragments in the regulation of synaptic gene transcription.
Subject(s)
Amyloid beta-Protein Precursor/genetics , Drosophila melanogaster/genetics , Gene Expression , Neurons/metabolism , Presynaptic Terminals/metabolism , RNA, Messenger/genetics , Amyloid beta-Protein Precursor/metabolism , Animals , Drosophila Proteins/genetics , Drosophila Proteins/metabolism , Drosophila melanogaster/metabolism , Humans , Presenilins/genetics , Presenilins/metabolism , R-SNARE Proteins/genetics , R-SNARE Proteins/metabolism , Synaptotagmin I/genetics , Synaptotagmin I/metabolismSubject(s)
Amyloid beta-Protein Precursor/genetics , Drosophila melanogaster/genetics , Nervous System/cytology , Synaptotagmin I/genetics , Animals , Animals, Genetically Modified , Drosophila melanogaster/cytology , Gene Expression , Humans , Nervous System/metabolism , RNA, Messenger/genetics , RNA, Messenger/metabolismABSTRACT
Measurement of α-synuclein level in the peripheral blood was proposed as a diagnostic test for Parkinson's disease. However, the results of these studies remain contradictory, probably because the examined samples included patients with different etiology of Parkinson's disease. To verify this assumption we studied the levels of α-synuclein in peripheral blood leukocytes of patients with Parkinson's disease associated with mutations in the gene of leucine-rich kinase 2 (LRRK2). The mean α-synuclein level was significantly lower in patients with LRRK2-associated Parkinson's disease (N=8) than in patients with sporadic form of the disease (N=33; p<0.02) and in controls (N=18; p<0.05). On the other hand, we found no differences in the level of α-synuclein level between patients with sporadic form of the disease and controls. We hypothesize that the level of α-synuclein in the peripheral blood largely depends on the etiology of the disease and cannot be used as a universal diagnostic test for Parkinson's disease.
Subject(s)
Parkinson Disease/genetics , Protein Serine-Threonine Kinases/genetics , alpha-Synuclein/metabolism , Aged , Female , Humans , Leucine-Rich Repeat Serine-Threonine Protein Kinase-2 , Leukocytes/cytology , Male , Middle Aged , Mutation , Parkinson Disease/bloodABSTRACT
Dendrimers are a new class of nonviral vectors for gene or drug transport. Dendrimer capacity to penetrate through the blood-brain barrier remaines little studied. Biotinylated polylysine dendrimer D5, similarly to human growth hormone biotinylated fragment covalently bound to D5 dendrimer, penetrates through the blood-brain barrier and accumulates in Drosophila brain after injection into the abdomen. Hence, D5 dendrimer can serve as a vector for peptide transport to brain cells.
Subject(s)
Blood-Brain Barrier/metabolism , Dendrimers/metabolism , Drosophila melanogaster/metabolism , Membrane Transport Proteins/metabolism , Animals , Biological Transport, Active , Brain/metabolism , Polylysine/metabolismABSTRACT
BACKGROUND AND PURPOSE: Mutations in LRRK2, encoding leucine-rich repeat kinase 2 (or Dardarin), cause autosomal dominant Parkinson's disease (AdPD) and are also found in sporadic PD (sPD). To investigate the frequency of LRRK2 mutations in a sample of Russian PD patients. METHODS: We sequenced the complete coding region of LRRK2 in 65 patients with AdPD and in 30 patients with sPD. Furthermore, in 20 patients with AdPD and in 159 patients with sPD we screened several common LRRK2 mutations (G2019S, R1441C/G/H, I2012T and I2020T). RESULTS: Five AdPD patients had the LRRK2 G2019S mutation (5.9%, 5/85). In addition, we discovered a novel LRRK2 variant V1613A in a family with a tremor dominant form of AdPD; this variant was not present in controls. We identified two patients with LRRK2 mutations in sPD: one with the G2019S mutation (0.5; 1/189) and another with the previously described R1441C mutation (0,5; 1/189). CONCLUSIONS: LRRK2 mutations are common amongst patients with PD in Russia. The results also show that the G2019S mutation is the most frequent. We identified one novel mutation in a functional region of LRRK2.
Subject(s)
Genetic Testing , Parkinson Disease/genetics , Protein Serine-Threonine Kinases/genetics , DNA Mutational Analysis , Female , Genetic Predisposition to Disease , Humans , Leucine-Rich Repeat Serine-Threonine Protein Kinase-2 , Male , Middle Aged , Mutation , Pedigree , Polymerase Chain Reaction , RussiaABSTRACT
The content of mRNA for alpha-synuclein (a key protein of the dopaminergic system) was elevated in the peripheral lymphocytes of patients with alcohol dependence syndrome. Increased level of alpha-synuclein mRNA was not associated with changes in the expression of NR4A2 gene encoding Nurrl, one of the main transcription factors of dopaminergic neurons.
Subject(s)
Alcoholism/genetics , Genetic Predisposition to Disease , Lymphocytes/metabolism , alpha-Synuclein/genetics , Adult , Analysis of Variance , DNA-Binding Proteins/genetics , Humans , Male , Middle Aged , Nuclear Receptor Subfamily 4, Group A, Member 2 , Transcription Factors/geneticsABSTRACT
Most cases of familial early-onset Alzheimer's disease are caused by mutations in the presenilin 1 (PS1) gene. However, the cellular functions of PS1 are unknown. We showed predominant localization of PS1 to cell-cell contacts of the plasma membrane in human prostate epithelial tissue and in a human epithelial cell line HEp2 stably transfected with an inducible PS1 construct. PS1 co-immunoprecipitated with beta-catenin from cell lysates of stable transfectants. Conversely, PS1 lacking the PS1-beta-catenin interaction site did not co-immunoprecipitate with beta-catenin and was not recruited to the cell-cell contacts. L cells, which do not form tight intercellular contacts, formed clusters of adhered cells after stable transfection with GFP-PS1 cDNA and demonstrated a clear preference for independent aggregation in the mixed cultures. However, L cells transfected with mutant GFP-PS1 constructs, which had a truncated N-terminus of PS1 or deleted PS1-beta-catenin interaction site, failed to form intercellular contacts. In addition, in primary cultures of mouse cortical neurons PS1 was highly concentrated on the surface of extended growth cones. Taken together, our results suggest an important role of PS1 in intercellular adhesion in epithelial cells and neurons.
Subject(s)
Cell Adhesion/physiology , Cytoskeletal Proteins/metabolism , Membrane Proteins/metabolism , Trans-Activators , Alzheimer Disease/physiopathology , Animals , Blotting, Western , Cell Adhesion/genetics , Cell Aggregation , Cells, Cultured , Cytoskeletal Proteins/genetics , Epithelial Cells/metabolism , Genes, Reporter , Humans , Immunohistochemistry , Intercellular Junctions/metabolism , L Cells , Male , Membrane Proteins/genetics , Mice , Microscopy, Confocal , Mutation , Neurons/metabolism , Neurons/ultrastructure , Precipitin Tests , Presenilin-1 , Prostate/cytology , Recombinant Fusion Proteins , Transfection , Tumor Cells, Cultured , beta CateninABSTRACT
Most familial early-onset Alzheimer's disease cases are caused by mutations in the presenilin 1 (PS1) gene. Subcellular localization of the endogenous PS1 is essential for understanding its function, interactions with proteins, and role in Alzheimer's disease. Although numerous studies revealed predominant localization of PS1 to endoplasmic reticulum and Golgi, there are conflicting reports on the localization of PS1 to the cell surface. We found that endogenous PS1 is highly expressed in T lymphocytes (Jurkat cells). Using a variety of methods, we present evidence that endogenous PS1 is localized to the cell surface in addition to intracellular membrane compartments. Moreover, PS1 appeared in high levels on the surface of lamellipodia upon adhesion of the cells to a collagen matrix. The redistribution of PS1 in adhered cells was strikingly similar to that of the well characterized adhesion protein CD44. Cell surface PS1 formed complexes in vivo with actin-binding protein filamin (ABP-280), which is known to form bridges between cell surface receptors and cytoskeleton and mediate cell adhesion and cell motility. Taken together, our results suggest a role of PS1 in cell adhesion and/or cell-matrix interaction.
Subject(s)
Cell Adhesion/physiology , Collagen , Membrane Proteins/metabolism , Algorithms , Alzheimer Disease , Amino Acid Sequence , Cell Membrane/physiology , Cell Membrane/ultrastructure , Cell Movement , Consensus Sequence , Contractile Proteins/physiology , Cytoplasm/physiology , Cytoplasm/ultrastructure , Extracellular Matrix/physiology , Filamins , Humans , Hyaluronan Receptors/physiology , Immunohistochemistry , Jurkat Cells , Microfilament Proteins/physiology , Microscopy, Electron, Scanning , Molecular Sequence Data , Peptide Library , Peptides/chemistry , Peptides/metabolism , Presenilin-1 , Receptors, Antigen, T-Cell/physiologyABSTRACT
Aggregated amyloid beta-protein (A beta) is a key component of the amyloid depositions found in the brains of patients with Alzheimer's disease. In contrast, in cerebrospinal fluid (CSF), A beta is found in a soluble form. The analysis of complexes of A beta with CSF proteins in a KBr gradient revealed an association of A beta only with free proteins and not with lipoprotein particles. Transthyretin (TTR), a second major CSF protein, formed SDS-stable complexes with A beta and significantly decreased the rate of A beta fibril formation. In physiological buffers and CSF, TTR exclusively decreased the level of A beta pentamers. Endogenous TTR-A beta complexes were detected in human CSF by immunoprecipitation. Using site-directed mutagenesis and computer-assisted modelling, we identified amino acid residues on the surface of the TTR monomer that interact with A beta. Specific TTR immunoreactivity was detected in multiple cortical neurons and astrocytes in the human brain. We propose that A beta binding proteins play a key role in the modulation of A beta aggregation and normally prevent amyloid formation in biological fluids and in the brain.
Subject(s)
Alzheimer Disease/metabolism , Amyloid beta-Peptides/metabolism , Brain/metabolism , Prealbumin/metabolism , Alzheimer Disease/cerebrospinal fluid , Alzheimer Disease/etiology , Amyloid/antagonists & inhibitors , Amyloid/biosynthesis , Amyloid/cerebrospinal fluid , Amyloid/chemistry , Amyloid/metabolism , Amyloid beta-Peptides/cerebrospinal fluid , Amyloid beta-Peptides/chemistry , Amyloidosis/etiology , Amyloidosis/metabolism , Brain/ultrastructure , Humans , Immunohistochemistry , Microscopy, Electron , Prealbumin/cerebrospinal fluid , Prealbumin/chemistry , Precipitin Tests , Protein BindingABSTRACT
The APB alpha domain in the amyloid beta-protein precursor (APP) promoter contains a nuclear factor binding domain with the core recognition sequence TCAGCT-GAC. Proteins in nuclear extracts from brain and numerous cell lines bind to this domain and it contributes approximately 10-30% to the basal APP promoter activity. Included in this domain is the CANNTG motif, which is recognized by basic helix-loop-helix transcription factors. The same motif is also present in the CDEI element of the yeast centromere and in the adenovirus major late promoter (AdMLP). Here we present evidence based on thermostability, relative binding affinity, eletrophoretic mobility and antibody recognition that the cellular proteins that bind to the APB alpha and CDEI motifs are USF. However, the relative binding affinity for the motifs is different. The affinity of USF for AdMLP is approximately 20-fold higher than for the APB alpha sequence and 5-fold higher than for the CDEI sequence. Mutational analysis suggested that the primary determinant for USF binding affinity resides within the octamer CAGCTGAC, which is composed of the E-box consensus sequence CANNTG followed by the dinucleotide AC. The human homolog of the mouse CDEI binding protein did not bind to either the CDEI sequence or APB alpha.
Subject(s)
Amyloid beta-Protein Precursor/genetics , Promoter Regions, Genetic , Transcription Factors/metabolism , Adenoviridae/genetics , Alternative Splicing , Animals , Base Sequence , Binding Sites/genetics , Brain/metabolism , Cattle , DNA, Complementary/genetics , DNA-Binding Proteins/genetics , HeLa Cells , Humans , In Vitro Techniques , Mice , Molecular Sequence Data , Protein Binding , Protein Biosynthesis , Rats , Upstream Stimulatory FactorsABSTRACT
The cardinal pathological features of Alzheimer disease are depositions of aggregated amyloid beta protein (A beta) in the brain and cerebrovasculature. However, the A beta is found in a soluble form in cerebrospinal fluid in healthy individuals and patients with Alzheimer disease. We postulate that sequestration of A beta precludes amyloid formation. Failure to sequester A beta in Alzheimer disease may result in amyloidosis. When we added A beta to cerebrospinal fluid of patients and controls it was rapidly sequestered into stable complexes with transthyretin. Complexes with apolipoprotein E, which has been shown to bind A beta in vitro, were not observed in cerebrospinal fluid. Additional in vitro studies showed that both purified transthyretin and apolipoprotein E prevent amyloid formation.
Subject(s)
Amyloid Neuropathies/prevention & control , Amyloid beta-Peptides/metabolism , Prealbumin/metabolism , Amino Acid Sequence , Computer Graphics , Humans , In Vitro Techniques , Models, Molecular , Molecular Sequence Data , Prealbumin/cerebrospinal fluid , Protein BindingABSTRACT
Epilepsy is a dominant trait in EL mice, a model for human complex partial seizures. We recently mapped the major gene, El-1, to chromosome 9 near the predicted location for the ceruloplasmin (Cp) gene. We now present evidence for a partial duplication in the Cp gene in EL mice. This Cp duplication is coinherited with seizures in backcross generations and is associated with enhanced expression of Cp mRNA and increased Cp oxidase activity. Moreover, the duplication is associated with an enhanced frequency of double recombinants, simulating negative interference. The findings are relevant to the basic mechanisms of epilepsy and to theories of genetic recombination and gene mapping.
Subject(s)
Ceruloplasmin/genetics , Disease Models, Animal , Epilepsy, Complex Partial/genetics , Mice, Inbred Strains/genetics , Mice, Neurologic Mutants/genetics , Multigene Family , Animals , Ceruloplasmin/biosynthesis , Chromosome Mapping , Copper/physiology , Crosses, Genetic , Crossing Over, Genetic , Epilepsy, Complex Partial/enzymology , Gene Expression Regulation, Enzymologic , Humans , Liver/enzymology , Mice , Mice, Inbred C57BL , Mice, Inbred DBA , Nerve Tissue Proteins/biosynthesis , Nerve Tissue Proteins/genetics , Polymerase Chain Reaction , Polymorphism, Restriction Fragment Length , Recombination, GeneticABSTRACT
A proband homozygous for the PiZ allele of the alpha-1-antitrypsin gene was found to be a heterozygous carrier of the additional nucleotide substitution (C-T) within the intron IV-exon V junction (position 9955 in intron IV, 3 bp upstream of its 3'-splice site). This mutation was not found in DNA from either the PiZ heterozygous parents or the PiZ homozygous brother of proband.