Structural signature of sporadic Creutzfeldt-Jakob disease.

BACKGROUND AND PURPOSE: Sporadic Creutzfeldt-Jakob disease (sCJD) is a rapidly progressive neurodegenerative disease caused by an abnormal isoform of the human prion protein. Structural magnetic resonance imaging in patients with pathologically confirmed sCJD was compared with cognitively normal individuals to identify a cortical thickness signature of sCJD. METHODS: This retrospective cross-sectional study compared patients with autopsy-confirmed sCJD with dementia (n = 11) with age- and sex-matched cognitively normal individuals (n = 22). We identified regions of interest (ROIs) in which cortical thickness was most affected by sCJD. Within patients with sCJD, the relationship between ROI cortical thickness and clinical measures (disease duration, cerebrospinal fluid tau and diffusion-weighted imaging abnormalities) was evaluated. RESULTS: Compared with cognitively normal individuals, patients with sCJD had significantly reduced cortical thickness in multiple ROIs, including the fusiform gyrus, precentral gyrus, precuneus and superior temporal gyrus bilaterally; the caudal middle frontal gyrus, superior frontal gyrus, postcentral gyrus, inferior temporal gyrus and transverse temporal gyrus in the left hemisphere; and the superior parietal lobule in the right hemisphere. Only one patient with sCJD had co-pathology consistent with Alzheimer's disease. Reduced cortical thickness did not correlate with disease duration, presence of diffusion restriction or elevated cerebrospinal fluid tau. CONCLUSION: Cortical signature changes in sCJD may reflect brain changes not captured by standard clinical measures. This information may be used with clinical measures to inform the progression of sCJD and patterns of prion protein spread throughout the brain. These results may have implications for prediction of symptomatic progression and plausibly for development of therapeutic strategies.

Axonal damage and astrocytosis are biological correlates of grey matter network integrity loss: a cohort study in autosomal dominant Alzheimer disease.

Brain development and maturation leads to grey matter networks that can be measured using magnetic resonance imaging. Network integrity is an indicator of information processing capacity which declines in neurodegenerative disorders such as Alzheimer disease (AD). The biological mechanisms causing this loss of network integrity remain unknown. Cerebrospinal fluid (CSF) protein biomarkers are available for studying diverse pathological mechanisms in humans and can provide insight into decline. We investigated the relationships between 10 CSF proteins and network integrity in mutation carriers (N=219) and noncarriers (N=136) of the Dominantly Inherited Alzheimer Network Observational study. Abnormalities in Aß, Tau, synaptic (SNAP-25, neurogranin) and neuronal calcium-sensor protein (VILIP-1) preceded grey matter network disruptions by several years, while inflammation related (YKL-40) and axonal injury (NfL) abnormalities co-occurred and correlated with network integrity. This suggests that axonal loss and inflammation play a role in structural grey matter network changes. Key points: Abnormal levels of fluid markers for neuronal damage and inflammatory processes in CSF are associated with grey matter network disruptions.The strongest association was with NfL, suggesting that axonal loss may contribute to disrupted network organization as observed in AD.Tracking biomarker trajectories over the disease course, changes in CSF biomarkers generally precede changes in brain networks by several years.

Neuropathology for the neuroradiologist: Antoni A and Antoni B tissue patterns.

Histologic patterns of cellular architecture often suggest a tissue diagnosis. Distinctive histologic patterns seen within the peripheral nerve sheath tumor schwannoma include the Antoni A and Antoni B regions. The purpose of this report is to review the significance of Antoni regions in the context of schwannomas.

Protein-protein interactions of alpha-synuclein in brain homogenates and transfected cells.

alpha-Synuclein is a highly conserved presynaptic protein with probable roles in normal synaptic development and plasticity as well as neurodegenerative disease, although its molecular function is not yet clear. To identify potential protein binding partners of alpha-synuclein, we performed co-immunoprecipitations using a monoclonal antibody (H3C) against its C-terminus. More than 20 detectable proteins were specifically co-immunoprecipitated from zebra finch and mouse forebrain extracts. One of these, with relative mobility of 55 kDa, was identified through microsequencing as a mixture of alpha- and beta-tubulin. Tubulin was specifically recovered from a mouse forebrain cytosolic extract by a GST/alpha-synuclein fusion protein immobilized on glutathione-Sepharose beads. In the converse experiment, alpha-synuclein bound to a column prepared from purified bovine brain tubulin immobilized upon CNBr-Sepharose. alpha-Synuclein does not appear to bind assembled microtubules, however, as alpha-synuclein did not pellet with polymerized microtubules in a standard assay for microtubule-associated proteins. Likewise, when a fusion construct of alpha-synuclein and green fluorescent protein (GFP) was expressed in African green monkey kidney epithelial (CV-1) cells, the fusion protein did not colocalize with endogenous microtubules. We conclude that alpha-synuclein may interact specifically with heterodimeric tubulin, but not microtubules, in the neuronal cytosol.

Epitope mapping and specificity of the anti-alpha-synuclein monoclonal antibody Syn-1 in mouse brain and cultured cell lines.

While alpha- and beta-synuclein largely overlap in their expression in the vertebrate brain, only alpha-synuclein accumulates in the fibrillar aggregates typical of Parkinson's disease. It is thus critical to have immunological reagents that distinguish between these two protein isoforms. The monoclonal antibody Syn-1 (Transduction Labs) has been frequently used for the specific detection of alpha-synuclein. In this report, the epitope for Syn-1 is localized within residues 91-99 of human alpha-synuclein. Sequence differences exist in this domain that account for the specificity of Syn-1 for alpha- versus beta-synuclein. However, Syn-1 also displays reactivity with additional species (approximately 45 kDa) in brain homogenates from both wild-type and alpha-synuclein null mice, indicating a potential for cross-reactivity with a protein species that is unrelated to alpha-synuclein in brain tissue or extracts.

Exposure to long chain polyunsaturated fatty acids triggers rapid multimerization of synucleins.

Detergent-stable multimers of alpha-synuclein have been found specifically in the brains of patients with Parkinson's disease and other neurodegenerative diseases. Here we show that recombinant alpha-synuclein forms multimers in vitro upon exposure to vesicles containing certain polyunsaturated fatty acid (PUFA) acyl groups, including arachidonoyl and docosahexaenoyl. This process occurs at physiological concentrations and much faster than in aqueous solution. PUFA-induced aggregation involves physical association with the vesicle surface via the large apolipoprotein-like lipid-binding domain that constitutes the majority of the protein. beta- and gamma-synucleins, as well as the Parkinson's disease-associated alpha-synuclein variants A30P and A53T, show similar tendencies to multimerize in the presence of PUFAs. Multimerization does not require the presence of any tyrosine residues in the sequence. The membrane-based interaction of the synucleins with specific long chain polyunsaturated phospholipids may be relevant to the protein family's physiological functions and may also contribute to the aggregation of alpha-synuclein observed in neurodegenerative disease.

Interaction of human alpha-Synuclein and Parkinson's disease variants with phospholipids. Structural analysis using site-directed mutagenesis.

alpha-Synuclein has been centrally implicated in neurodegenerative disease, and a normal function in developmental synaptic plasticity has been suggested by studies in songbirds. A variety of observations suggest the protein partitions between membrane and cytosol, a behavior apparently conferred by a conserved structural similarity to the exchangeable apolipoproteins. Here we show that the capacity to bind lipids is broadly distributed across exons 3, 4, and 5 (encoding residues 1-102). Binding to phosphatidylserine-containing vesicles requires the presence of all three exons, while binding to phosphatidic acid can be mediated by any one of the three. Consistent with a "class A2" helical binding mechanism, lipid association is disrupted by introduction of charged residues along the hydrophobic face of the predicted alpha-helix and also by biotinylation of conserved lysines (which line the interfacial region). Circular dichroism spectroscopy reveals a general correlation between the amount of lipid-induced alpha-helix content and the degree of binding to PS-containing vesicles. Two point mutations associated with Parkinson's disease have little (A30P) or no (A53T) effect on lipid binding or alpha-helicity. These results are consistent with the hypothesis that alpha-synuclein's normal functions depend on an ability to undergo a large conformational change in the presence of specific phospholipids.