Tauopathies and synuclein and tau

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Adamec, E., P. Mohan, et al. (2002). "Calpain activation in neurodegenerative diseases: confocal immunofluorescence study with antibodies specifically recognizing the active form of calpain 2." Acta Neuropathol (Berl) 104(1): 92-104.
The calcium-activated protease calpain cleaves a variety of biologically important proteins and serves, therefore, as a key regulator of many cellular functions. Activation of both main isoforms, calpain 1 and calpain 2, was demonstrated previously in Alzheimer's disease. In this report, antibodies specifically recognizing the active form of calpain 2 were used to investigate calpain 2 activation in a broad range of neurodegenerative diseases, utilizing multiple-label confocal immunofluorescence imaging. With rare exceptions, the active form of calpain 2 was found in colocalization with hyperphosphorylated tau protein. Aggregates of mutated huntingtin, alpha-synuclein, or unidentified protein in motor neuron disease type of frontotemporal dementia were always negative. These findings indicate that calpain 2 activation is not a general response to protein aggregation. In tauopathies, more pathological inclusions were labeled for hyperphosphorylated tau than for activated calpain 2. The extent of colocalization varied in both a disease-specific and cell-type specific manner. The active form of calpain 2 was detected in 50-75% of tau neurofibrillary pathology in Alzheimer's disease, Alzheimer neurofibrillary changes and Down's syndrome, as well as in the accompanying Alzheimer-type tau pathology in diffuse Lewy bodies disease, progressive supranuclear palsy, and corticobasal degeneration. For glial cells, only 10-25% of tuft-shaped astrocytes, glial plaques, or coiled bodies contained activated calpain 2. The majority of Pick bodies were negative. The association of calpain 2 activation with hyperphosphorylated tau might be the result of an attempt by the calpain proteolytic system to degrade the tau protein aggregates. Alternatively, calpain 2 could be directly involved in tau hyperphosphorylation by modulating protein kinase activities. Overall, these results provide evidence of the important role of the calpain proteolytic system in the pathogenesis of neurodegenerative diseases with tau neurofibrillary pathology.

Alafuzoff, I., S. Helisalmi, et al. (2000). "Selegiline treatment and the extent of degenerative changes in brain tissue of patients with Alzheimer's disease." Eur J Clin Pharmacol 55(11-12): 815-9.
BACKGROUND: A beneficial effect of selegiline (L-deprenyl) in Alzheimer's disease (AD) has been reported in several clinical studies. METHODS: The brain tissue from 17 deceased patients, members of a double-blind clinical trial to assess the potential benefit of selegiline in AD, were analysed. FINDINGS: In our study, the decrease in the Mini-Mental State Examination (MMSE) scores during the progress of the disease had been significantly influenced by selegiline treatment. Prior to death, the MMSE scores were significantly higher in those patients receiving selegiline than in those receiving placebo. However, according to our results, none of the lesions critical for AD diagnosis, such as counts of senile/neuritic plaques, neurofibrillary tangles or beta-A4 load, were influenced by the selegiline treatment. INTERPRETATION: In conclusion, according to our study, mechanisms other than neuronal degeneration seen as lesions critical for AD diagnosis are influenced by selegiline treatment, leading to the functional benefit found in AD.

Arai, Y., M. Yamazaki, et al. (2001). "Alpha-synuclein-positive structures in cases with sporadic Alzheimer's disease: morphology and its relationship to tau aggregation." Brain Res 888(2): 287-296.
Alzheimer's disease (AD) and Parkinson's disease share common clinical and pathological features. In this study, we examined the relationship between AD pathology and alpha-synuclein aggregation. The frequency and distribution of alpha-synuclein-positive structures were systematically investigated in 27 cases with sporadic AD by alpha-synuclein immuno-histochemistry. Thirteen (48.2%) of 27 cases had various alpha-synuclein-positive structures as well as Lewy bodies. The frequency and density of senile plaques and neurofibrillary tangles were not significantly different between cases with alpha-synuclein structures and those without. alpha-Synuclein-positive structures were found most frequently in the amygdala. The alpha-synuclein-positive inclusions that are different from Lewy bodies were observed at the highest rate in the hippocampus. The discovery of alpha-synuclein as the constituent of Lewy bodies facilitated the detection of Lewy-related structures even in AD cases with widespread and numerous neurofibrillary tangles. alpha-Synuclein-positive inclusions except for Lewy bodies are exposed, and the distribution of them indicates that Lewy body formation may be influenced by the degree of tau aggregation. This study also supports the suggestion that cases with AD pathology can be classified into two groups according to the existence or absence of alpha-synuclein aggregation.

Arnold, S. E., L. Y. Han, et al. (2000). "Quantitative neurohistological features of frontotemporal degeneration." Neurobiol Aging 21(6): 913-9.
Frontotemporal degeneration (FTD) is a neurodegenerative condition that has been principally associated with frontal lobe dementia. In this study, we compared neuropathological abnormalities in frontal, hippocampal, and calcarine cortices from patients assigned a diagnosis of FTD, normal elderly and Alzheimer's disease (AD). Densities of Nissl-stained neurons and lesions which were immunolabeled for tau, beta-amyloid (Abeta), alpha- and beta-synuclein, ubiquitin, glial fibrillary acidic protein (GFAP) and CD68 antigen were determined using computer-assisted, non-biased quantitative microscopy. We found that FTD frontal and hippocampal regions exhibited marked neuron loss, abundant ubiquitin-immunoreactive (ir) dystrophic neurites, GFAP-ir astrocytes, and CD68-ir microglia, while calcarine cortex was spared. No alpha- or beta-synuclein-ir lesions were observed, and neither the density of tau-ir neurofibrillary tangles nor that of Abeta-ir plaques in FTD exceeded normal controls. In addition, there were no neuropathological differences between FTD subjects who presented clinically with a frontal lobe dementia versus an AD-like dementia. These findings indicate that FTD is a category of neurodegnerative dementias with varying clinical presentations that is characterized by the progressive degeneration of select populations of cortical neurons. The molecular neurodegenerative mechanisms that lead to FTD remain to be elucidated.

Culvenor, J. G., C. A. McLean, et al. (1999). "Non-Abeta component of Alzheimer's disease amyloid (NAC) revisited. NAC and alpha-synuclein are not associated with Abeta amyloid." Am J Pathol 155(4): 1173-81.
alpha-Synuclein (alphaSN), also termed the precursor of the non-Abeta component of Alzheimer's disease (AD) amyloid (NACP), is a major component of Lewy bodies and Lewy neurites pathognomonic of Parkinson's disease (PD) and dementia with Lewy bodies (DLB). A fragment of alphaSN termed the non-Abeta component of AD amyloid (NAC) had previously been identified as a constituent of AD amyloid plaques. To clarify the relationship of NAC and alphaSN with Abeta plaques, antibodies were raised to three domains of alphaSN. All antibodies produced punctate labeling of human cortex and strong labeling of Lewy bodies. Using antibodies to alphaSN(75-91) to label cortical and hippocampal sections of pathologically proven AD cases, we found no evidence for NAC in Abeta amyloid plaques. Double labeling of tissue sections in mixed DLB/AD cases revealed alphaSN in dystrophic neuritic processes, some of which were in close association with Abeta plaques restricted to the CA1 hippocampal region. In brain homogenates alphaSN was predominantly recovered in the cytosolic fraction as a 16-kd protein on Western analysis; however, significant amounts of aggregated and alphaSN fragments were also found in urea extracts of SDS-insoluble material from DLB and PD cases. NAC antibodies identified an endogenous fragment of 6 kd in the cytosolic and urea-soluble brain fractions. This fragment may be produced as a consequence of alphaSN aggregation or alternatively may accelerate aggregation of the full-length alphaSN.

Duda, J. E., B. I. Giasson, et al. (2002). "Concurrence of alpha-synuclein and tau brain pathology in the Contursi kindred." Acta Neuropathol (Berl) 104(1): 7-11.
Previous genetic analysis of the familial Parkinson's disease Contursi kindred led to the identification of an Ala53Thr pathogenic mutation in the alpha-synuclein gene. We have re-examined one of the original brains from this kindred using new immunohistochemical reagents, thioflavin S staining and immunoelectron microscopy. Surprisingly, we uncovered a dense burden of alpha-synuclein neuritic pathology and rare Lewy bodies. Immunoelectron microscopy demonstrated fibrillar alpha-synuclein-immunoreactive aggregates. Unexpected tau neuritic and less frequent perikaryal inclusions were also observed. Some inclusions were comprised of both proteins with almost complete spatial disparity. We suggest that it is important to recognize that the neurodegenerative process caused by the Ala53Thr mutation in alpha-synuclein is not identical to that seen in typical idiopathic Parkinson's disease brains.

Duyckaerts, C., M. A. Colle, et al. (1999). "[Alzheimer's disease: lesions and their progression]." Rev Neurol (Paris) 155 Suppl 4: S17-27.
Alzheimer disease appears to be a stereotyped mode of reaction of the central nervous system to various types of aggression such as different mutations involving various proteins, trisomy 21 or repeated head trauma as in dementia pugilistica. Rather than a disease, it appears to be a clinicopathological syndrome due to various causes. Lesions may be considered under 3 headings: neurofibrillary pathology, A beta peptide deposits and loss (neuronal and synaptic). Neurofibrillary pathology includes the neurofibrillary tangle, the crown of the senile plaque and the neuropil threads. All those lesions are characterized by the same ultrastructure--i.e. the accumulation of paired helical filaments--and the same immunohistochemistry: they are labelled by antibodies directed against the tau proteins. The amyloid deposits, present in the core of the senile plaque and in the vascular walls, are made of a 40 to 42 amino-acids long peptide, named A beta, derived from the amyloid precursor protein (APP). Antibodies directed against the A beta peptide also label diffuse deposits that are devoid of the tinctorial affinities and of the biochemical properties of amyloid substances. Those diffuse deposits are insufficient to cause dementia since they may be observed in high density in aged people without intellectual deterioration. Neuronal loss occurs after neurofibrillary pathology. The role of the synaptic pathology remains discussed. Besides tau proteins, A beta peptide and APP, several other proteins may play an important role: apolipoprotein E which could act as a chaperone protein, inducing or facilitating the formation of amyloid, presenilins 1 and 2, mutated in some cases of familial Alzheimer disease, alpha-synuclein which is present in the Lewy bodies found in Parkinson disease and in dementia with Lewy bodies. The A beta deposits are diffusely distributed in the cerebral cortex; the neurofibrillary changes have a hierarchical distribution. The progression of the neurofibrillary pathology in the various cortical areas follow a stereotyped sequence that may help to grade the severity of the disease. Progression may take decades. The relations between aging and Alzheimer disease are still poorly understood. Frequency of Alzheimer type lesions in old people could suggest that they are the inevitable burden of age, but this has been discussed.

Farrer, M., K. Gwinn-Hardy, et al. (1999). "The genetics of disorders with synuclein pathology and parkinsonism." Hum Mol Genet 8(10): 1901-5.
Despite being considered the archetypal non-genetic neurological disorder, genetic analysis of Parkinson's disease has shown that there are at least three genetic loci. Furthermore, these analyses have suggested that the phenotype of the pathogenic loci is wider than simple Parkinson's disease and may include Lewy body dementia and some forms of essential tremor. Identification of alpha-synuclein as the first of the loci involved in Parkinson's disease and the identification of this protein in pathological deposits in other disorders has led to the suggestion that it may share pathogenic mechanisms with multiple system atrophy, Alzheimer's disease and prion disease and that these mechanisms are related to a synuclein pathway to cell death. Finally, genetic analysis of the synuclein diseases and the tau diseases may indicate that this synuclein pathway is an alternative to the tau pathway to cell death.

Farrer, M., D. M. Maraganore, et al. (2001). "alpha-Synuclein gene haplotypes are associated with Parkinson's disease." Hum Mol Genet 10(17): 1847-51.
We report haplotype analysis of the alpha-synuclein gene in Parkinson's disease (PD), extending earlier reports of an association with a polymorphism within the gene promoter. This analysis showed significant differences in haplotypes between PD cases and controls. Our analyses demonstrate that genetic variability in the alpha-synuclein gene is a risk factor for the development of PD. These genetic findings are analogous to the tau haplotype over-represented in progressive supranuclear palsy and further extend the similarity in the etiologies and pathogeneses of the synucleinopathies and tauopathies.
 

Forman, M. S., M. L. Schmidt, et al. (2002). "Tau and alpha-synuclein pathology in amygdala of Parkinsonism-dementia complex patients of Guam." Am J Pathol 160(5): 1725-31.
Amyotrophic lateral sclerosis/parkinsonism-dementia complex (ALS/PDC) is a progressive neurodegenerative disorder of Chamorro residents of Guam and the Mariana Islands, characterized by abundant neuron loss and tau neurofibrillary pathology similar to that observed in Alzheimer's disease (AD). A variety of neurodegenerative diseases with tau pathology including ALS/PDC also have alpha-synuclein positive pathology, primarily in the amygdala. We further characterized the tau and alpha-synuclein pathology in the amygdala of a large series of 30 Chamorros using immunohistochemical and biochemical techniques. Tau pathology was readily detected in both affected and unaffected Chamorros. In contrast, alpha-synuclein pathology was detected in 37% of patients with PDC but not detected in Chamorros without PDC or AD. The alpha-synuclein aggregates often co-localized within neurons harboring neurofibrillary tangles suggesting a possible interaction between the two proteins. Tau and alpha-synuclein pathology within the amygdala is biochemically similar to that observed in AD and synucleinopathies, respectively. Thus, the amygdala may be selectively vulnerable to developing both tau and alpha-synuclein pathology or tau pathology may predispose it to synuclein aggregation. Furthermore, in PDC, tau and alpha-synuclein pathology occurs independent of beta-amyloid deposition in amygdala thereby implicating the aggregation of these molecules in the severe neurodegeneration frequently observed in this location.


Goedert, M., R. Jakes, et al. (1998). "Intraneuronal filamentous tau protein and alpha-synuclein deposits in neurodegenerative diseases." Biochem Soc Trans 26(3): 463-71.

Goedert, M. (1999). "Filamentous nerve cell inclusions in neurodegenerative diseases: tauopathies and alpha-synucleinopathies." Philos Trans R Soc Lond B Biol Sci 354(1386): 1101-18.
Alzheimer's disease and Parkinson's disease are the most common neurodegenerative diseases. They are characterized by the degeneration of selected populations of nerve cells that develop filamentous inclusions before degeneration. The neuronal inclusions of Alzheimer's disease are made of the microtubule-associated protein tau, in a hyperphosphorylated state. Recent work has shown that the filamentous inclusions of Parkinson's disease are made of the protein alpha-synuclein and that rare, familial forms of Parkinson's disease are caused by missense mutations in the alpha-synuclein gene. Besides Parkinson's disease, the filamentous inclusions of two additional neurodegenerative diseases, namely dementia with Lewy bodies and multiple system atrophy, have also been found to be made of alpha-synuclein. Abundant filamentous tau inclusions are not limited to Alzheimer's disease. They are the defining neuropathological characteristic of frontotemporal dementias such as Pick's disease, and of progressive supranuclear palsy and corticobasal degeneration. The recent discovery of mutations in the tau gene in familial forms of frontotemporal dementia has provided a direct link between tau dysfunction and dementing disease. The new work has established that tauopathies and alpha-synucleinopathies account for most late-onset neurodegenerative diseases in man. The formation of intracellular filamentous inclusions might be the gain of toxic function that leads to the demise of affected brain cells.

Golbe, L. I., A. M. Lazzarini, et al. (2001). "The tau A0 allele in Parkinson's disease." Mov Disord 16(3): 442-7.
Parkinson's disease (PD) is primarily an alpha-synucleinopathy, rather than a tauopathy, but there is evidence for an indirect association of tau with the pathogenetic process in PD. We therefore assessed the frequency in PD of the tau A0 allele, a dinucleotide repeat marker that has been associated with a sporadic tauopathy, progressive supranuclear palsy (PSP). We found the A0 allele to comprise 79.2% of 758 alleles from PD patients and 71.2% of 264 control alleles (P = 0.008). We also performed a meta-analysis of three previous reports, two of which failed to produce statistically significant results. Taken together, they also support a PD/A0 allelic association, even after correction for misdiagnosis of PSP as PD (P< 0.001). The A0/A0 genotype frequency in our patients (62.3%) did not differ significantly from that in controls (53.0%, P = 0.062), but the meta-analysis, even after correction for misdiagnosis, showed a significant result, with P = 0.002. The frequency of A0 allele and the A0/A0 genotype were compatible with Hardy-Weinberg equilibrium. The frequency of the A0 allele and the A0/A0 genotype in our patients with familial PD was not significantly greater than in those with sporadic PD. We conclude that the tau protein may play a small role in the pathogenesis of PD and that biochemical characterization of this role may suggest opportunities for PD prophylaxis.

Hardy, J. and K. Gwinn-Hardy (1998). "Genetic classification of primary neurodegenerative disease." Science 282(5391): 1075-9.
Review During the past 10 years (the "decade of the brain"), some of the genetic causes of many of the primary neurodegenerative diseases, which include Alzheimer's disease, Parkinson's disease, Huntington's disease, amyotrophic lateral sclerosis, prion disease, and many ataxic syndromes, have been found. These breakthroughs mean that for many of these diseases we now know the initiating trigger as well as the final outcome. These diseases have many pathological mechanisms in common, and there may be relatively few pathways to neuronal death seen in these disorders. Thus, treatment strategies developed for a particular disease may be found to have efficacy in more than one disorder.

Hardy, J. and K. Gwinn-Hardy (1999). "Neurodegenerative disease: a different view of diagnosis." Mol Med Today 5(12): 514-7.
Neurodegenerative diseases have traditionally been defined as clinicopathological entities. Although this has been a productive paradigm in terms of the development of treatment strategies, molecular genetic approaches have revealed that there is overlap between different entities in pathogenic mechanisms. In this article, it is argued that neurodegenerative disease should also be thought of as the consequences of sequential biochemical processes, and that some parts of these processes appear to operate in more than one disease entity. Defining these pathways and, in particular, developing an appreciation of the commonalities between different diseases, should aid in the development of therapies that are effective in several diseases.

Higgins, J. J., I. Litvan, et al. (1998). "Progressive supranuclear gaze palsy is in linkage disequilibrium with the tau and not the alpha-synuclein gene." Neurology 50(1): 270-3.
We studied two candidate genes, tau (tau) and alpha-synuclein (SNCA), for evidence of linkage disequilibrium on a group of unrelated individuals with progressive supranuclear palsy (PSP) and a group of age-matched control subjects. The tau alpha1 allele and the tau alpha1alpha1 genotype were overrepresented in individuals with PSP and the tau polymorphism was in linkage disequilibrium with the PSP disease locus when a recessive inheritance model was employed. We also report a lack of evidence to support linkage disequilibrium between PSP and the SNCA candidate Parkinson's disease gene on chromosome 4q21-q23.

Higuchi, M., M. Tashiro, et al. (2000). "Glucose hypometabolism and neuropathological correlates in brains of dementia with Lewy bodies." Exp Neurol 162(2): 247-56.
Cerebral glucose metabolism using positron emission tomography (PET) with (18)F-fluorodeoxyglucose was examined in 11 patients with probable Alzheimer's disease (AD), 6 patients with probable, and 1 patient with autopsy-confirmed dementia with Lewy bodies (DLB) as well as in 10 age-matched normal control subjects. Among widespread cortical regions showing glucose hypometabolism in the DLB group, the metabolic reduction was most pronounced in the visual association cortex compared to that in the AD group. Using a metabolic ratio of 0.92 in the visual association cortex as a cutoff (mean-2 SD of normal control subjects), DLB could be distinguished from AD with a sensitivity of 86% and a specificity of 91%. In contrast, apolipoprotein E4 allele frequency and cerebrospinal fluid tau levels did not differ significantly between the two groups. In order to further dissect out neuropathological correlates of the dysfunctional occipital lobe, postmortem brains from 19 patients with AD and 17 with DLB as well as 11 brains from normal controls were examined. A distinct and extensive spongiform change with coexisting gliosis was variably noted throughout cerebral white matter with relative sparing of gray matter in DLB. Notably, the white matter spongiform change and gliosis was most prominently and consistently found in the occipital region of DLB, and the severity of the spongiform change in each brain region generally paralleled to the regional difference in reduced glucose metabolism between the living AD and DLB patients. These findings suggest that (1) among several potential antemortem biomarkers in the diagnosis of DLB, measures of the glucose metabolism in the occipital cortex may be an informative diagnostic aid to distinguish DLB from AD; and (2) a pathological process that generates widespread spongiform change and gliosis in long projection fibers may contribute, at least in part, to the characteristic imaging features of DLB.

Jellinger, K. A. (2000). "Morphological substrates of mental dysfunction in Lewy body disease: an update." J Neural Transm Suppl 59: 185-212.
Mental dysfunction including cognitive, behavioural changes, mood disorders, and psychosis are increasingly recognized in patients with Parkinson's disease (PD) and related disorders. Their morphological correlates are complex due to multiple system degeneration. CNS changes contributing to cognitive changes in PD include 1. Dysfunction of subcorticocortical networks with neuron losses in a) the dopaminergic nigrostriatal loop, causing striato-(pre)frontal deafferentation and mesocortico-limbic system (medial substantia nigra, ventral tegmentum); b) noradrenergic (locus coeruleus), and serotonergic systems (dorsal raphe nuclei), c) cholinergic forebrain system (nucleus basalis of Meynert, etc), and d) specific nuclei of amygdala and limbic system (thalamic nuclei, hippocampus); 2. Limbic and/or cortical Lewy body and Alzheimer type pathologies with loss of neurons and synapses, 3. Combination of subcortical, cortical, and other pathologies. In general, degeneration of subcortical and striato-frontal networks causes cognitive, executive, behavioural, and mood disorders but less severe dementia than cortical changes which, when present in sufficient numbers, are important factors for overt dementia. In PD, cortical tau pathology with similar or differential patterns than in Alzheimer disease (AD) shows significant linear correlation with cognitive decline. In dementia with Lewy bodies (DLB), the second most frequent cause of dementia in the elderly, cortical Lewy bodies (LB) may or may not be associated with amyloid plaques and neuritic AD lesions. They predominantly affect the limbic system with less frequent isocortical Braak stages, whereas the cholinergic forebrain system is more severely affected than in AD. Both neuritic degeneration in limbic system in PD and DLB and the density of cortical synapse markers correlate with neuritic AD pathology and less with cortical LB counts. Apolipoprotein E epsilon4 allele frequency may represent a common genetic background for both AD and LB pathologies but there are different proportions of plaques between DLB (less Abeta1-40) and AD (more frequent Abeta1-40). Familial parkinsonism with dementia, linked to chromosome 17 (frontotemporal dementia with Parkinsonism (FTDP-17), and other tauopathies pathologically resembling PD plus AD, are often related to mutations of the tau gene, whereas familial PD with alpha-synuclein and Parkin mutations usually show no cognitive impairment. Mood disorders, in particular depression, and psychotic complications in both PD and DLB are related to complex involvement of noradrenergic and serotonergic systems, not confirmed in AD with depression, and both the prefrontal and limbic dopaminergic systems. The specific contributions of cortical and subcortical pathologies to mental dysfunction in PD and related disorders, their relationship to AD, and their genetic and aetiological backgrounds await further elucidation.

Johnson, W. G. (2000). "Late-onset neurodegenerative diseases--the role of protein insolubility." J Anat 196 ( Pt 4): 609-16.
Recently, mutations of the alpha-synuclein gene were found to cause dominantly inherited Lewy-body Parkinson's disease (PD) and alpha-synuclein was identified as a major component of the Lewy body. However, the cause of the common form of PD, with a multifactorial rather than autosomal dominant inheritance pattern, remains unknown. Alpha-synuclein precipitates slowly and apparently spontaneously at high concentration in solution and the mutations that cause PD accelerate precipitation. Other dominantly inherited late-onset or adult-onset dominantly inherited neurodegenerative diseases are associated with precipitation of proteins. In Alzheimer disease, beta-amyloid and tau abnormalities are present and in prion disorders, prion proteins are found. In Huntington disease, a disorder with expanded CAG repeats, huntingtin precipitates occur. In dominantly inherited spinocerebellar ataxias, also expanded CAG repeat disorders, the corresponding ataxin protein precipitates are found. In multiple system atrophy, alpha-synuclein precipitates are encountered and in progressive supranuclear palsy, tau precipitates occur. In familial amyotrophic lateral sclerosis, a group of dominantly inherited disorders, SOD1 precipitates are found. Most of these disorders can involve the basal ganglia in some way. Since similar processes seem to affect neurons of adults or older individuals and since a relatively limited group of proteins seems to be involved, each producing a form of neurodegeneration, it is possible that certain common features are present that affect this group of proteins. Candidates include a conformational shift, as in prions, an abnormality of the ubiquitin-proteosome pathway, as seen in PD, an abnormality of a pathway preventing precipitation (e.g. chaperonins), or potentiation of a pathway promoting precipitation (e.g. gamma-glutamyl-transpeptidase) or apoptosis. Elucidation of the pathways causing this protein insolubilisation is the first step towards approaching prevention and reversal in these late-onset neurodegenerative diseases.

Judkins, A. R., M. S. Forman, et al. (2002). "Co-occurrence of Parkinson's disease with progressive supranuclear palsy." Acta Neuropathol (Berl) 103(5): 526-30.
Parkinson's disease (PD) and progressive supranuclear palsy (PSP) are distinct neurodegenerative disorders. We describe an 81-year-old woman with 3 years of progressive gait unsteadiness, frequent falls, and mild cognitive dysfunction, all considered clinically to be an early fronto-temporal neurodegenerative disorder. She died of an acute myocardial infarction. Examination of her brain revealed alpha-synuclein- and tau-positive inclusions diagnostic of PD and PSP. Immunoelectron microscopy and Western blot analysis confirmed combined PD/PSP. This case provides strategies for the reliable molecular validation of concomitant PD and PSP, and demonstrates the utility of these techniques in patients with atypical clinical presentations.

Kotzbauer, P. T., J. Q. Trojanowsk, et al. (2001). "Lewy body pathology in Alzheimer's disease." J Mol Neurosci 17(2): 225-32.
Lewy bodies, the characteristic pathological lesion of substantia nigra neurons in Parkinson's disease (PD), are frequently observed to accompany the amyloid plaque and neurofibrillary tangle pathology of Alzheimer's disease (AD). However the typical anatomic distribution of Lewy bodies in AD is distinct from PD. The most common site of occurrence is the amygdala, where Lewy bodies are observed in approximately 60% of both sporadic and familial AD. Other common sites of occurrence include the periamygdaloid and entorhinal cortex, while neocortical and brainstem areas develop Lewy bodies in a lower percentage of cases. In contrast, dementia with Lewy bodies (DLB), defined by widespread neocortical and brainstem Lewy bodies but frequently accompanied by variable levels of AD-type pathology, represents the other end of a spectrum of pathology associated with dementia. The observation of Lewy bodies in familial AD cases suggests that like neurofibrillary tangles, the formation of Lewy bodies can be induced by the pathological state caused by Abeta-amyloid overproduction. The role of Lewy body formation in the dysfunction and degeneration of neurons remains unclear. The protein alpha-synuclein appears to be an important structural component of Lewy bodies, an observation spurred by the discovery of point mutations in the alpha-synuclein gene linked to rare cases of autosomal dominant PD. Further investigation of alpha-synuclein and its relationship to pathological conditions promoting Lewy body formation in AD, PD, and DLB may yield further insight into pathogenesis of these diseases.

Kurosinski, P., M. Guggisberg, et al. (2002). "Alzheimer's and Parkinson's disease--overlapping or synergistic pathologies?" Trends Mol Med 8(1): 3-5.
Alzheimer's disease (AD) and Parkinson's disease (PD) are the two most common neurodegenerative disorders in humans. They are characterized by insoluble protein deposits; beta-amyloid plaques and tau-containing neurofibrillary lesions in AD, and alpha-synuclein-containing Lewy bodies in PD. As a significant percentage of patients have clinical and pathological features of both diseases, the patho-cascades of the two diseases might overlap. For the first time, new animal models that express multiple transgenes provide the tools to dissect the pathogenic pathways and to differentiate between additive and synergistic effects.

Kuusisto, E., A. Salminen, et al. (2001). "Ubiquitin-binding protein p62 is present in neuronal and glial inclusions in human tauopathies and synucleinopathies." Neuroreport 12(10): 2085-90.
We examined the immunoreactivity of ubiquitin-binding protein p62 and its association with ubiquitin (Ub), alpha-synuclein, and paired helical filament (PHF)-tau in the affected brain areas of human tauopathies and synucleinopathies. Ubiquitin-binding protein p62 is a widely expressed protein that can bind to Ub noncovalently and is involved in several signalling pathways, making p62 a candidate regulator of Ub-mediated proteolysis. We show that p62 immunoreactivity co-localizes with neuronal and glial Ub-containing inclusions in Alzheimer's disease, Pick's disease, dementia with Lewy bodies, Parkinson's disease, and multiple system atrophy. This is the first demonstration of a common protein component, apart from Ub, that is present in both PHF-tau and alpha-synuclein inclusions. In both tauo- and synucleinopathies, the staining patterns for p62 and Ub were markedly similar, suggesting that a common mechanism which requires interaction of p62 and Ub contributes to the formation of PHF-tau and alpha-synuclein inclusions.

Lippa, C. F., H. Fujiwara, et al. (1998). "Lewy bodies contain altered alpha-synuclein in brains of many familial Alzheimer's disease patients with mutations in presenilin and amyloid precursor protein genes." Am J Pathol 153(5): 1365-70.
Missense mutations in the alpha-synuclein gene cause familial Parkinson's disease (PD), and alpha-synuclein is a major component of Lewy bodies (LBs) in sporadic PD, dementia with LBs (DLB), and the LB variant of Alzheimer's disease (AD). To determine whether alpha-synuclein is a component of LBs in familial AD (FAD) patients with known mutations in presenilin (n = 65) or amyloid precursor protein (n = 9) genes, studies were conducted with antibodies to alpha-, beta-, and gamma-synuclein. LBs were detected with alpha- but not beta- or gamma-synuclein antibodies in 22% of FAD brains, and alpha-synuclein-positive LBs were most numerous in amygdala where some LBs co-localized with tau-positive neurofibrillary tangles. As 12 (63%) of 19 FAD amygdala samples contained alpha-synuclein-positive LBs, these inclusions may be more common in FAD brains than previously reported. Furthermore, alpha-synuclein antibodies decorated LB filaments by immunoelectron microscopy, and Western blots revealed that the solubility of alpha-synuclein was reduced compared with control brains. The presence of alpha-synuclein-positive LBs was not associated with any specific FAD mutation. These studies suggest that insoluble alpha-synuclein aggregates into filaments that form LBs in many FAD patients, and we speculate that these inclusions may compromise the function and/or viability of affected neurons in the FAD brain.

Lovestone, S. and D. M. McLoughlin (2002). "Protein aggregates and dementia: is there a common toxicity?" J Neurol Neurosurg Psychiatry 72(2): 152-61.
This review considers some of the recent advances made in the understanding of the pathogenic proteins known to aggregate and be implicated in neurodegenerative dementing disorders. It concentrates on the two most obvious candidates for the role of toxic protein in Alzheimer's disease (AD)--beta-amyloid peptide and tau--but also considers other proteins in this disorder and in less common but equally devastating diseases.

Lucking, C. B. and A. Brice (2000). "Alpha-synuclein and Parkinson's disease." Cell Mol Life Sci 57(13-14): 1894-908.
The involvement of alpha-synuclein in neurodegenerative diseases was first suspected after the isolation of an alpha-synuclein fragment (NAC) from amyloid plaques in Alzheimer's disease (AD). Later, two different alpha-synuclein mutations were shown to be associated with autosomal-dominant Parkinson's disease (PD), but only in a small number of families. However, the discovery that alpha-synuclein is a major component of Lewy bodies and Lewy neurites, the pathological hallmarks of PD, confirmed its role in PD pathogenesis. Pathological aggregation of the protein might be responsible for neurodegeneration. In addition, soluble oligomers of alpha-synuclein might be even more toxic than the insoluble fibrils found in Lewy bodies. Multiple factors have been shown to accelerate alpha-synuclein aggregation in vitro. Therapeutic strategies aimed to prevent this aggregation are therefore envisaged. Although little has been learned about its normal function, alpha-synuclein appears to interact with a variety of proteins and membrane phospholipids, and may therefore participate in a number of signaling pathways. In particular, it may play a role in regulating cell differentiation, synaptic plasticity, cell survival, and dopaminergic neurotransmission. Thus, pathological mechanisms based on disrupted normal function are also possible.

Martin, G. M. (2000). "Molecular mechanisms of late life dementias." Exp Gerontol 35(4): 439-43.
A brief overview of the molecular pathology of dementia of the Alzheimer type (DAT), frontotemporal dementias (FTD), and Lewy body dementias (LBD) is preceded by a discussion of the evolutionary biological basis for the types of gene action responsible for the emergence of late life dementias. The beta amyloid cascade theory of the pathogenesis of DAT still predominates, but possible upstream events are being explored. Some familial forms of FTD have been shown to result from dominant mutations in the microtubular associated protein tau. A key element in pathogenesis is a shift in the ratios of various isoforms. Rare forms of Parkinson disease have been associated with dominant mutations in alpha synuclein, a protein of probable importance for synaptic plasticity. Aberrations in the metabolism of this protein (which is found in Lewy body fibrillar material) may therefore be of importance to the genesis of some LBD cases.

Marui, W., E. Iseki, et al. (2000). "Occurrence of human alpha-synuclein immunoreactive neurons with neurofibrillary tangle formation in the limbic areas of patients with Alzheimer's disease." J Neurol Sci 174(2): 81-4.
We examined alpha-synuclein immunoreactivity in the brains from 23 patients with Alzheimer's disease (AD) and two patients with Down's syndrome. In ten of the 23 AD cases and both the two Down's syndrome cases, alpha-synuclein immunoreactivities were observed in the neurons of the limbic areas, predominantly of the amygdala. Nearly all alpha-synuclein-positive neurons had tau-positive neurofibrillary tangles (NFT) in the same neurons, and these consisted of intermingled-type and superimposed-type. By immunoelectron microscopy, the intermingled-type revealed aggregations of alpha-synuclein-positive filamentous components, which were in continuity with paired helical filaments (PHF), while the superimposed-type revealed accumulations of alpha-synuclein-positive non-filamentous components in PHF bundles. These findings suggest that alpha-synuclein can accumulate in PHF and form filamentous aggregations in neurons of the limbic areas in AD cases.

Morris, H. R., J. R. Vaughan, et al. (2000). "Multiple system atrophy/progressive supranuclear palsy: alpha-Synuclein, synphilin, tau, and APOE." Neurology 55(12): 1918-20.
Article abstract-Alpha synuclein, tau, synphilin, and APOE genotypes were analyzed in patients with multiple system atrophy (MSA) and progressive supranuclear palsy (PSP) and controls. The predisposing effect of the tau insertion polymorphism to the development of PSP is confirmed. However, no effect of alpha-synuclein, synphilin, or APOE variability on the development of PSP, or of tau, alpha-synuclein, APOE, or synphilin gene variability on the development of MSA, are demonstrated.

Mukaetova-Ladinska, E. B., F. Garcia-Siera, et al. (2000). "Staging of cytoskeletal and beta-amyloid changes in human isocortex reveals biphasic synaptic protein response during progression of Alzheimer's disease." Am J Pathol 157(2): 623-36.
We have examined the relationships between dementia, loss of synaptic proteins, changes in the cytoskeleton, and deposition of beta-amyloid plaques in the neocortex in a clinicopathologically staged epidemiological cohort using a combination of biochemical and morphometric techniques. We report that loss of synaptic proteins is a late-stage phenomenon, occurring only at Braak stages 5 and 6, or at moderate to severe clinical grades of dementia. Loss of synaptic proteins was seen only after the emergence of the full spectrum of tau and beta-amyloid pathology in the neocortex at stage 4, but not in the presence of beta-amyloid plaques alone. Contrary to previous studies, we report increases in the levels of synaptophysin, syntaxin, and SNAP-25 at stage 3 and of alpha-synuclein and MAP2 at stage 4. Minimal and mild clinical grades of dementia were associated with either unchanged or elevated levels of synaptic proteins in the neocortex. Progressive aggregation of paired helical filament (PHF)-tau protein could be detected biochemically from stage 2 onwards, and this was earliest change relative to the normal aging background defined by Braak stage 1 that we were able to detect in the neocortex. These results are consistent with the possibility that failure of axonal transport associated with early aggregation of tau protein elicits a transient adaptive synaptic response to partial de-afferentation that may be mediated by trophic factors. This early abnormality in cytoskeletal function may contribute directly to the earliest clinically detectable stages of dementia.

Mukaetova-Ladinska, E. B., J. Hurt, et al. (2000). "Alpha-synuclein inclusions in Alzheimer and Lewy body diseases." J Neuropathol Exp Neurol 59(5): 408-17.
Alpha-synuclein has assumed particular neuropathological interest in the light both of its identification as a non-beta-amyloid plaque constituent in Alzheimer disease (AD), and the recent association between dominant inheritance of Parkinson disease (PD) and 2 missense mutations at positions 30 and 53 of the synuclein protein. We report a systematic study of alpha-synuclein, tau, and ubiquitin immunoreactivity in representative neurodegenerative disorders of late life. The alpha-synuclein association with Lewy bodies is variable, peripheral, and is not stable with respect to proteases or acid treatment, whereas there is no association with Pick bodies. Stable patterns of immunoreactivity included neurites and a novel inclusion body. Although there is an overlap between the presence of Lewy bodies and stable alpha-synuclein immunoreactivity, this is seen only in the presence of concomitant neuropathological features of AD. The novel alpha-synuclein inclusion body identified in pyramidal cells of the medial temporal lobe in particular was found in AD and in the Lewy body variant of AD, and was associated neither with ubiquitin nor tau protein. The inclusion is therefore neither a Lewy body nor a PHF-core body, but may be confused with the Lewy body, particularly in the Lewy body variant of AD. Abnormal processing of alpha-synuclein leading to its deposition in the form of proteolytically stable deposits is a particular feature of the intermediate stages of AD.

Munoz, D. G. (1999). "Stains for the differential diagnosis of degenerative dementias." Biotech Histochem 74(6): 311-20.
Our understanding of the structural substrates underlying the dementia syndrome has been transformed by the introduction of the Gallyas silver stain and the application of immunostains for tau, ubiquitin, and alpha-synuclein. Visualization of sequential changes in Alzheimer's disease and the recognition of a new substrate for dementia and dementia with argyrophilic grains, are two of the advances related to the application of the Gallyas method. The specificity of alpha-synuclein for recognizing Lewy bodies enables the unequivocal diagnosis of dementia with Lewy bodies. The diverse entities that constitute the Pick complex can be identified by applying immunostains for tau and ubiquitin in addition to the Gallyas silver stain.

Rozemuller, A. J., P. Eikelenboom, et al. (2000). "Activated microglial cells and complement factors are unrelated to cortical Lewy bodies." Acta Neuropathol (Berl) 100(6): 701-8.
Inflammatory mechanisms have been demonstrated in Alzheimer's disease (AD) but their presence in other neurodegenerative disorders is not well documented. Complement factors and activated microglia have been reported in the substantia nigra of Parkinson's disease (PD). In the present study we investigated the cingulate gyrus of 25 autopsied patients with clinically and neuropathologically well-documented PD, with or without dementia, for the presence of (activated) microglial cells and their relation with Lewy body (LB)-bearing neurons. In addition, we studied the presence of complement factors in LBs. Of the 25 patient, 15 were clinically demented, fulfilling criteria for dementia with LBs (DLB); 7 also fulfilled CERAD morphological criteria for probable or definite Alzheimer type of dementia. Microglia clustering was seen around congophilic plaques with or without tau pathology. Microglial cells were not associated with LB-bearing neurons or noncongophilic plaques. The cortex of DLB patients without AD plaques did not show more microglial cells than the cortex of non-demented controls. The number of microglia was the lowest in young control patients who died immediately after trauma. Complement factor C3d was occasionally seen in diffusely ubiquinated neurons but late complement factors were not detected in these neurons. Double staining for complement and alpha-synuclein was negative, suggesting the absence of complement in LBs. In contrast, AD plaques in the same sections showed complement factors C3c, C3d, C1q and C5-9. In conclusion, we have found no evidence that inflammatory mechanism are involved in LB formation in cerebral cortex.

Szpak, G. M., E. Lewandowska, et al. (2001). "Lewy body variant of Alzheimer's disease and Alzheimer's disease: a comparative immunohistochemical study." Folia Neuropathol 39(2): 63-71.
Immunohistochemistry (IHC) and ultrastructural study were performed on 19 demented autopsy cases of sporadic Alzheimer's disease (AD). Semiquantitative IHC assessment of the pathological changes, according to the criteria of the Consortium to Establish a Registry of Alzheimer's Disease (CERAD) and the Consortium on Dementia with Lewy Bodies, showed morphological hallmarks of AD in 18 demented patients. It was found that 11 of these cases fulfilled criteria for "pure" AD, whereas the remaining 7 cases, with mixed findings, Lewy bodies (LBs) and Lewy-related dystrophic neurites, neuritic plaques (NP) and sometimes neurofibrillary tangles (NFT), met the criteria for Lewy body variant of Alzheimer's disease (LBV). One case with brain stem and cortical LBs but without NP and NFT was finally diagnosed as a pure form of dementia with Lewy bodies (DLB). Regional distribution and semiquantitative assessment frequency of alpha-synuclein-immunoreactive LBs, tau-immunoreactive NFT and beta-amyloid immunoreactive senile plaques, were compared between LBVand AD. Ultrastructural examination confirmed the filamental structure of cortical LBs. In conclusion, IHC study including antibody to alpha-synuclein, the sensitive marker for Lewy bodies, revealed the coexistence of brain stem and cortical LBs and pathological features of AD in a great part of dementia cases. Patients with mixed, LBs, NP and sometimes NFT pathology, fulfilled neuropathological CERAD criteria for LBV. Semiquantitative comparative IHC study, according to LBs- and NFT-scores and CERAD NP-scores showed in the LBV group a significantly lower frequency of NFT coexisting with neocortical LBs than in the group with pure form of AD.

Takanashi, M., S. Ohta, et al. (2002). "Mixed multiple system atrophy and progressive supranuclear palsy: a clinical and pathological report of one case." Acta Neuropathol (Berl) 103(1): 82-7.
We report a patient who showed pathological features of both multiple system atrophy (MSA) and progressive supranuclear palsy (PSP) at autopsy. The clinical features included severe cerebellar ataxia, autonomic failure, and rigid-akinetic parkinsonism. The clinical diagnosis was MSA. Pathological examination showed severe neuronal loss with gliosis in the putamen, substantia nigra, inferior olive, and the pontine nucleus, and numerous glial cytoplasmic inclusions. In addition, moderate neuronal loss with gliosis was observed in the globus pallidus and subthalamic nucleus, and neurofibrillary tangles and tufted astrocytes were seen in the basal ganglia and the brain stem. These findings indicate that the patient had both MSA and PSP. Double-labeling immunofluorescence in the brain stem showed alpha-synuclein immunoreactivity localized in the oligodendrocytes and phosphorylated tau immunoreactivity in the neurons and the glia. Co-existence of synucleinopathy and tauopathy is rare.

Terada, S., H. Ishizu, et al. (2000). "Tau-negative astrocytic star-like inclusions and coiled bodies in dementia with Lewy bodies." Acta Neuropathol (Berl) 100(5): 464-8.
To evaluate glial lesions in cases of dementia with Lewy bodies (DLB), we studied the brains of four patients with DLB. Astrocytic star-like inclusions, which resembled tufted astrocytic fibrillary tangles in shape, were found in the cortex of two of these cases. In addition, coiled bodies were found in the white matter of the cerebrum in two cases. The astrocytic star-like inclusions were immunohistochemically negative for tau protein, ubiquitin and alpha-synuclein. The coiled bodies were immunohistochemically negative for tau protein but immunopositive for ubiquitin and alpha-synuclein. These results suggest that in DLB a primary degenerative process takes place in both glial cells and neurons.

Tomidokoro, Y., Y. Harigaya, et al. (2001). "Brain Abeta amyloidosis in APPsw mice induces accumulation of presenilin-1 and tau." J Pathol 194(4): 500-6.
APPsw transgenic mice (Tg2576) overproducing mutant amyloid beta protein precursor (betaAPP) show substantial brain Abeta amyloidosis and behavioural abnormalities. To clarify the subsequent abnormalities, the disappearance of neurons and synapses and dystrophic neurite formation with accumulated proteins including hyperphosphorylated tau were examined. Tg2576 demonstrated substantial giant core plaques and diffuse plaques. The number of neurons was significantly decreased in the areas containing the amyloid cores compared with all other areas and corresponding areas in non-transgenic littermates in sections visualized by Nissl plus Congo red double staining (p<0.001). The presynaptic protein alpha-synuclein and postsynaptic protein drebrin were also absent in the amyloid cores. betaAPP and presenilin-1 were accumulated in dystrophic neurites in and around the core plaques. Tau phosphorylated at five independent sites was detected in the dystrophic neurites in the amyloid cores. Thus, the giant core plaques replaced normal brain tissues and were associated with subsequent pathological features such as dystrophic neurites and the appearance of hyperphosphorylated tau. These findings suggest a potential role for brain Abeta amyloidosis in the induction of secondary pathological steps leading to mental disturbance in Alzheimer's disease.

Trojanowski, J. Q. and V. M. Lee (1999). "Transgenic models of tauopathies and synucleinopathies." Brain Pathol 9(4): 733-9.
Rapidly emerging concepts about the pathobiology and defining phenotypes of two major classes of neurodegenerative disease known as tauopathies and synucleinopathies are bringing these diseases into shaper focus. Significantly, recent research has substantially advanced understanding of these neurodegenerative disorders thereby providing fresh opportunities for the development of transgenic (TG) mouse models. Since the availability of such animal models will accelerate efforts to discover more effective therapies, we review the current status of efforts to generate informative TG mouse models for tauopathies and synucleinopathies and other neurodegenerative disorders characterized by prominent filamentous brain lesions.

Trojanowski, J. Q. and V. M. Lee (2000). ""Fatal attractions" of proteins. A comprehensive hypothetical mechanism underlying Alzheimer's disease and other neurodegenerative disorders." Ann N Y Acad Sci 924: 62-7.
Abnormal protein-protein interactions that result in the formation of intracellular and extracellular aggregates of proteinacious fibrils are common neuropathological features of many, albeit diverse, neurodegenerative disorders, such as sporadic and familial Alzheimer's disease, Parkinson's disease, amyotrophic lateral sclerosis, and prion encephalopathies. Indeed, increasing evidence suggests that abnormal protein-protein interactions and/or the lesions that result from the aggregation of pathological protein fibrils could play a mechanistic role in the dysfunction and death of neurons or glial cells in neurodegenerative diseases. Here we propose that "fatal attractions" between brain proteins are the key pathological events underlying Alzheimer's disease and a large number of other seemingly diverse neurodegenerative disorders. This hypothesis predicts that the abnormal interaction between normal brain proteins alters their conformation and promotes the assembly of these pathological conformers into filaments that progressively accumulate as intracellular or extracellular fibrous deposits in the central nervous system. Further, the transformation of the normal proteins into pathological conformers is predicted to result in losses of critical functions, and the disease proteins or their progressive accumulation into filamentous aggregates are predicted to acquire neurotoxic properties, all of which culminate in the dysfunction and death of affected brain cells. Thus, the "fatal attractions" hypothesis describes a plausible unifying mechanism that accounts for the onset/progression of Alzheimer's disease and a large number of other seemingly unrelated neurodegenerative disorders characterized neuropathologically by filamentous brain lesions formed by different proteins.

Tsuboi, Y., J. E. Ahlskog, et al. (2001). "Lewy bodies are not increased in progressive supranuclear palsy compared with normal controls." Neurology 57(9): 1675-8.
OBJECTIVE: To determine the frequency of Lewy bodies (LB) in progressive supranuclear palsy (PSP). BACKGROUND: LB are characteristic of PD, but are also found in normal controls and in other neurodegenerative diseases, especially AD. METHOD: The authors evaluated the brains of 72 consecutive cases of pathologically confirmed PSP and 98 normal controls, ranging in age from 60 to 100 years, with immunohistochemistry for alpha-synuclein. RESULTS: LB and Lewy neurites were found in 13 cases of PSP, with the most numerous LB and Lewy neurites in the basal forebrain and amygdala; most cases also had LB in the substantia nigra. The frequency of LB in the substantia nigra (12%) was comparable to the frequency of LB in controls (9%). CONCLUSIONS: In contrast to increased frequency of LB in AD, there is no apparent interaction between LB and the tau pathology in PSP.

Yang, F., K. Ueda, et al. (2000). "Plaque-associated alpha-synuclein (NACP) pathology in aged transgenic mice expressing amyloid precursor protein." Brain Res 853(2): 381-3.
Patients with the Lewy body variant (LBV) of Alzheimer's disease (AD) have ubiquitinated intraneuronal and neuritic accumulations of alpha-synuclein and show less neuron loss and tau pathology than other AD patients. Aged Tg2576 transgenic mice overexpressing human betaAPP695. KM670/671NL have limited neuron loss and tau pathology, but frequent ubiquitin- and alpha-synuclein-positive, tau-negative neurites resembling those seen in the LBV of AD.