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Apolipoprotein E (apoE), a plasma apolipoprotein that plays a central role in lipoprotein metabolism, is localized in the senile plaques, congophilic angiopathy, and neurofibrillary tangles of Alzheimer disease. Late-onset familial and sporadic Alzheimer disease patients have an increased frequency of one of the three common apoE alleles, e4, suggesting apoE4 is associated with increased susceptibility to disease. To follow up on this suggestion, we compared the binding of synthetic amyloid .8 (.3/A4) peptide to purified apoE4 and apoE3, the most common isoform. Both isoforms bound synthetic P/A4 peptide, the primary constituent of the plaque and angiopathy, forming a complex that resisted dissociation by boiling in SDS. Oxygen-mediated complex formation was implicated because binding was increased in oxygenated buffer, reduced in nitrogen-purged buffer, and prevented by reduction with dithiothreitol or 2-mercaptoethanol. Binding of fI/A4 peptide was saturable at 10-4 M peptide and required residues 12-28. Examination of apoE fragments revealed that residues 244-272 are critical for complex formation. Both oxidized apoE4 and apoE3 bound fi/A4 peptide; however, binding to apoE4 was observed in minutes, whereas binding to apoE3 required hours. In addition, apoE4 did not bind (8/A4 peptide at pH < 6.6, whereas apoE3 bound P/A4 peptide from pH 7.6 to 4.6. Together these results indicate differences in the two isoforms in complexing with the f/A4 peptide. Binding of P/A4 peptide by oxidized apoE may determine the sequestration or targeting of either apoE or ./A4 peptide, and isoformspecific differences in apoE binding or oxidation may be involved in the pathogenesis of the intra-and extracellular lesions of Alzheimer disease.

Amyloid -peptide (AP) deposition in senile plaques and cerebral vessels is a neuropathological feature of Alzheimer disease (AD). We examined the possibility that commonly observed variability in Af8 deposition in late-onset AD might be related to apolipoprotein E genotype (APOE gene; the two most common alleles are 3 and 4), since APOE4 is a susceptibility gene for late-onset AD and apolipoprotein E interacts strongly with A.8 in vitro. In an autopsy series of brains of late-onset AD patients, we found a strong association of APOE4 allele with increased vascular and plaque Af3 deposits. Late-onset AD patients with one or two APOE4 alleles have a distinct neuropathological phenotype compared with patients homozygous for APOE3.

Pathological degeneration of neurons in Huntington's disease and associated neurodegenerative disorders is directly correlated with the expansion of CAG repeats encoding polyglutamines of extended length. The physical properties of extended polyglutamines and the intracellular consequences of expression of polyglutamine expansion have been the object of intensive investigation. We have extended the range of lengths of polyglutamine produced by recombinant DNA methodology by constructing a library of CAG͞CAA repeats coding for a range of 25-300 glutamine residues. We have investigated the subcellular localization, interaction with other polyglutamine-containing polypeptides, and the physical properties of aggregated forms of polyglutamine in the cell. Extended polyQ aggregated in the cytoplasm and was only transported to the nucleus when a strong nuclear localization signal was present. Polyglutamine below pathological lengths could be captured in aggregates and transported to ectopic cell locations. The CREB-binding protein (CBP), containing a homopolymeric stretch of 19 glutamines, was likewise found to coaggregate in a polyglutamine-dependent manner, suggesting that pathology in polyglutamine disease may result from cellular depletion of normal proteins containing polyglutamine. We have observed a striking detergent resistance in aggregates produced from polyglutamine of pathological length. This observation has led to the development of a f luorescence-based assay exploiting the detergent resistance of polyglutamine aggregates that should facilitate high-throughput screening for agents that suppress polyglutamine aggregation in cells.

We have analyzed the modulation of amyloid (3-protein precursor (APP) gene expression in human umbilical vein endothelial cells (HUVEC). The level of the APP mRNA transcripts increased as HUVEC reached confluency. In confluent culture the half-life of the APP mRNA was 4 hr. Treatment of the cells with human recombinant interleukin 1 (IL-1), phorbol 12-myristate 13-acetate, or heparin-binding growth factor 1 enhanced the expression of APP gene in these cells, but calcium ionophore A23187 and dexamethasone did not. The protein kinase C inhibitor 1-(isoquinolinsulfonyl)-2-methylpiperazine (H7) inhibited IL-1-mediated increase of the level of APP transcripts. To map IL-1-responsive elements of the APP promoter, truncated portions of the APP promoter were fused to the human growth hormone reporter gene. The recombinant plasmids were transfected into mouse neuroblastoma cells, and the cell medium was assayed for the human growth hormone. A 180-base-pair region of the APP promoter located between position -485 and -305 upstream from the transcription start site was necessary for IL-1-mediated induction of the reporter gene. This region contains the upstream transcription factor AP-1 binding site. These results suggest that IL-1 upregulates APP gene expression in HUVEC through a pathway mediated by protein kinase C, utilizing the upstream AP-1 binding site of the APP promoter.The amyloid A3-protein precursor (APP) gene codes for a family of proteins, each containing a 42-amino acid fragment called amyloid 3 or A4 protein, that is found in brains and the cerebrovasculature of Alzheimer disease, Down syndrome, hereditary cerebral hemorrhage (Dutch type), and aging (1)(2)(3)(4)(5). The APP gene is transcriptionally active in a variety of tissues, highly conserved in evolution, maps to human chromosome 21 (6-10), and probably has no mutations associated with Alzheimer disease (11, 12). Transcripts containing three similar but nonidentical open reading frames have been identified (13)(14)(15)(16)(17). In situ hybridization studies show a very complex pattern of the APP gene expression in brain (18-23).Different levels of APP mRNAs were detected in neurons, some glial cells, and cells that compose blood vessels, presumably some endothelial cells (23). The detection of APP mRNA in these cells strengthens the possibility that at least one form of amyloid 83-protein-cerebrovascular-could originate locally from blood vessels (24, 25).The importance ofunderstanding the regulation ofthe APP gene is underscored by two observations. First, there are differences between Alzheimer disease patients and controls in the levels of APP mRNAs in certain brain regions (19,23,(26)(27)(28)(29)(30). Second, the difference in the level of APP mRNAs between trisomy 21 Down-syndrome patients and controls having two chromosomes 21 was higher than the expected 3:2 ratio (9). In the absence of structural mutations, aberrant levels of the precursor protein may contribute to pathology. These observations suggest that there is aberrant regulation...

Hemorrhagic fever with renal syndrome (HFRS) comprises a variety of clinically similar diseases of viral etiology that are endemic to and sporadically epidemic throughout the Eurasian continent and Japan. Although HFRS has not been reported in North America, viruses that are antigenically similar to HFRS agents were recently isolated from rodents in the United States. Examination and comparison of eight representative isolates from endemic disease areas and from regions with no known associated HFRS indicate that these viruses represent a new and unique group that constitutes a separate genus in the Bunyaviridae family of animal viruses.

The PRNP gene, encoding the amyloid precursor protein that is centrally involved in Creutzfeldt-Jakob disease (CJD), has an unstable region of five variant tandem octapeptide coding repeats between codons 51 and 91. We screened a total of 535 individuals for the presence of extra repeats in this region, including patients with sporadic and

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