A neuropathological hallmark of Alzheimer disease (AD) is a widespread amyloid deposition. We analyzed the entire amino acid sequences in an amyloid preparation and found, in addition to the major I3/A4-protein (AP) fragment, two unknown peptides. We raised antibodies against synthetic peptides using subsequences ofthese peptides. These antibodies immunostained amyloid in neuritic and diffuse plaques as well as vascular amyloid. Electron microscopic analysis demonstrated that the immunostaining was localized on amyloid fibrils. We have isolated an apparently full-length cDNA encoding a 140-amino-acid protein within which two previously unreported amyloid sequences are encoded in tandem in the most hydrophobic domain. We tentatively named this 35-amino acid peptide NAC (non-A(8 component of AD amyloid) and its precursor NACP. NAC is the second component, after A.8, identified chemically in the purified AD amyloid preparation. Secondary structure predictions indicate that the NAC peptide sequence has a strong tendency to form (structures consistent with its association with amyloid. NACP is detected as a M, 19,000 protein in the cytosolic fraction of brain homogenates and comigrates on immunoblots with NACP synthesized in Escherichia coli from NACP cDNA. NACP mRNA is expressed principally in brain but is also expressed in low concentrations in all tissues examined except in liver, suggesting its ubiquitous and brain-specific functions. The availability of the cDNA encoding full-length NACP should help to elucidate the mechanisms of amyloidosis in AD.Amyloid deposition in the neuritic plaque and blood vessels is the most consistent neuropathology in Alzheimer disease (AD) (1, 2). The major constituent of amyloid has been found to be a 39-to 43-amino acid amyloid 13/A4-protein (AP3) (3,4) derived from its precursor, APP (5-8). The isolation of APP cDNA prompted a burst-of research in AD, culminating in the identification of APP mutations in several familial types of AD (9-12). Thus, APP and AP have been proposed to play a key role in the pathogenesis of this disease (13, 14). Additionally, heparan sulfate proteoglycan, ferritin, immunoglobulins, and many acute-phase proteins, such as a1-antichymotrypsin (ACT), apolipoprotein E, complements, serum amyloid P, and trace peptides were also reported to be associated with plaque core amyloid (15-29), although supportive biochemical data demonstrating their presence in amyloid preparations are not yet available, raising the possibility that those might not be the intrinsic components of amyloid. We have further pursued the biochemical examination of the intrinsic constituents of AD amyloid by purification in SDS and sequencing, and we detected a previouslyThe publication costs of this article were defrayed in part by page charge payment. This article must therefore be hereby marked "advertisement" in accordance with 18 U.S.C. §1734 solely to indicate this fact.unrecognized component that we tentatively call NAC (non-AP component of AD amyloid) in this communication...

TorsinA, a protein with homology to yeast heat shock protein104, has previously been demonstrated to colocalize with a-synuclein in Lewy bodies, the pathological hallmark of Parkinson's disease. Heat shock proteins are a family of chaperones that are both constitutively expressed and induced by stressors, and that serve essential functions for protein refolding and/or degradation. Here, we demonstrate that, like torsinA, specific molecular chaperone heat shock proteins colocalize with a-synuclein in Lewy bodies. In addition, using a cellular model of a-synuclein aggregation, we demonstrate that torsinA and specific heat shock protein molecular chaperones colocalize with a-synuclein immunopositive inclusions. Further, overexpression of torsinA and specific heat shock proteins suppress a-synuclein aggregation in this cellular model, whereas mutant torsinA has no effect. These data suggest that torsinA has chaperone-like activity and that the disease-associated GAG deletion mutant has a loss-of-function phenotype. Moreover, these data support a role for chaperone proteins, including torsinA and heat shock proteins, in cellular responses to neurodegenerative inclusions.

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Increasing evidence suggests that ␣-synuclein is a common pathogenic molecule in several neurodegenerative diseases, particularly in Parkinson's disease. To understand ␣-synuclein pathology, we investigated molecules that interact with ␣-synuclein in human and rat brains and identified tubulin as an ␣-synuclein binding-/associated protein. Tubulin co-localized with ␣-synuclein in Lewy bodies and other ␣-synuclein-positive pathological structures. Tubulin initiated and promoted ␣-synuclein fibril formation under physiological conditions in vitro. These findings suggest that an interaction between tubulin and ␣-synuclein might accelerate ␣-synuclein aggregation in diseased brains, leading to the formation of Lewy bodies. The non-␤-amyloid (A␤)1 component of Alzheimer's disease amyloid, or NAC, originally detected in an amyloid-enriched fraction, was shown to be a fragment of its precursor, NACP, by cloning of the full-length cDNA (1). Later, NACP turned out to be a human homologue of Torpedo synuclein (2). Therefore, it is also referred to as human ␣-synuclein (3). ␣-Synuclein is abundant in presynaptic terminals of neurons (4). Recently, two missense mutations in the ␣-synuclein gene (5) were discovered in certain pedigrees with familial Parkinson's disease and were shown to segregate with the illness (6, 7). Shortly thereafter, ␣-synuclein was identified as the major filamentous component of Lewy bodies (LBs) in Parkinson's disease (8, 9) and of cytoplasmic inclusions in multiple system atrophy (MSA) (10 -12).Thus, ␣-synuclein appears to be a common pathogenic molecule in these diseases.Although the physiological role of ␣-synuclein is unknown, ␣-synuclein has the property of forming fibrils by itself in vitro, and mutations of ␣-synuclein accelerate the fibril formation (13,14). However, the vast majority of cases of neurodegenerative diseases associated with LBs or with ␣-synuclein pathology, such as Parkinson's disease, dementia with Lewy bodies (DLB), MSA, and the LB variant of Alzheimer's disease, are sporadic, where wild-type ␣-synuclein has shown to be abnormally accumulated as fibrillar structures. It is therefore likely that at some stage(s) in the fibril formation of ␣-synuclein, either the nucleation and/or the elongation steps should be somehow accelerated in diseased brains, or alternatively, some degradation process(es) of abnormal structures of ␣-synuclein might be defective in those patients (15).With respect to the amyloidogenesis of Alzheimer's disease, it was demonstrated in vitro that a seed of NAC can accelerate A␤ fibril formation, and conversely, a seed of A␤ can promote NAC fibril formation (16). Similarly, heterogeneous molecules could also be involved in the formation of ␣-synuclein fibrils, leading to pathological structures of ␣-synuclein such as LBs.In this study, we performed a biochemical investigation of molecules that interact with ␣-synuclein in the human brain, and we identified tubulin as one of the ␣-synuclein binding/ associated proteins. This interaction was confirmed by co...

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Ribonucleoprotein (RNP) cores of influenza virus A/PR/8/34 were dissociated into RNA polymerase (PB1-PB2-PA complex)-associated genome RNA and nuclear protein (NP) fractions by CsCl centrifugation. The RNA polymerase-RNA complexes were capable of catalyzing the endonucleolytic cleavage of capped RNA, the initiation of primer-dependent RNA synthesis, and the synthesis of small-sized RNA, but were unable to synthesize template-sized RNA. By adding the NP protein to the RNA polymerase-RNA complexes, RNP (RNA polymerase-RNA-NP) complexes were reconstituted; they synthesized template-sized transcripts as did native RNP cores. These observations are consistent with the model where viral RNA polymerase is composed of the three P proteins while NP is essential for the elongation of RNA chains. RNP was completely dissociated into RNA-free proteins (PB1, PB2, PA, and NP) and a protein-free genome RNA fraction by centrifugation in cesium trifluoroacetate (CsTFA) and glycerol. By mixing the protein and RNA fractions, primer-dependent RNA-synthesizing activity was regained. These complexes, however, produced only small-sized RNA, presumably due to incorrect assembly of NP on viral RNA.