Biomedical subjects

T Wisniewski

Publications and source records attributed to T Wisniewski.

At least 37 records · Page 2Linked to original sources

PubMed1999

Biochemical and conformational variability of human prion strains in sporadic Creutzfeldt-Jakob disease.

The pathogenesis of prion (PrP) diseases is thought to be related to conformational changes of a normal cellular protein, PrPC, into a protease resistant protein called PrPSc, which is infectious by itself. A difficulty with this 'protein only' hypothesis is the existence of numerous PrP strains, that require PrPSc to have multiple conformations. Sporadic Creutzfeldt-Jakob disease (CJD), which accounts for nearly 80% of human prionoses, was reported to include at least two 'strains' termed types 1 and 2 which differ by electrophoretic patterns of their proteinase K (PK)-resistant fragments (PrP27-30). We have analyzed the biochemical and structural properties of PrPSc and PrP27-30 isolates from six sporadic CJD patients. Fourier transform-infra-red spectroscopy, PrP27-30 glycosylation patterns and studies of PK sensitivity revealed a striking heterogeneity. Furthermore, one isolate yielded a PrP27-30 fragment with a lower mobility clearly different from previously described sporadic CJD types. Although the average beta-sheet content was higher among type 1 isolates, there was overlap between the two types. Our study suggests that human sporadic CJD-related prions display a significant heterogeneity.

Aged↗

PubMed1999

Inhibition of neurite outgrowth by familial Alzheimer's disease-linked presenilin-1 mutations.

Two (P117L; M146L) familial Alzheimer's disease (FAD)-causing presenilin-1 (PS1) mutations have been tested fortheir effect in stably transfected mouse neuroblastoma (N2a) cell lines. The P117L mutation is associated with the earliest onset of AD reported so far (24 years), while the M146L is less pathogenic with the onset at about 43 years. Overexpression of wild-type (wt) PS1 gene was associated with the marked increase in the number and the length of neuritic outgrowths accompanied by accumulation of PS1 immunoreactivity in neurites. The highly pathogenic P117L mutation completely suppressed this effect and the pattern of PS1 immunolabeling resembled a cup structure with all immunoreactivity gathered at one pole of the cell. The effect of less pathogenic M146L mutation was similar, but not as pronounced. These findings suggest that one of the normal functions of PS1 may be the control of neurite outgrowth, and the inhibitory effect of two FAD-linked mutations stresses its importance in the cellular mechanism that leads to the development of Alzheimer's disease (AD).

Alzheimer Disease↗

PubMed1999

Localization of alpha-tocopherol transfer protein in the brains of patients with ataxia with vitamin E deficiency and other oxidative stress related neurodegenerative disorders.

Vitamin E (alpha-tocopherol) is an essential nutrient and an important antioxidant. Its plasma levels are dependent upon oral intake, absorption and transfer of the vitamin to a circulating lipoprotein. The latter step is controlled by alpha-tocopherol transfer protein (alpha-TTP), which is a 278 amino acid protein encoded on chromosome 8, known to be synthesized in the liver. Mutations in alpha-TTP are associated with a neurological syndrome of spinocerebellar ataxia, called ataxia with vitamin E deficiency (AVED). Earlier studies suggested that alpha-TTP is found only in the liver. In order to establish whether alpha-TTP is expressed in the human brain, and what relationship this has to AVED, we studied immunohistochemically the presence of alpha-TTP in the brains of a patient with AVED, normal subjects, and patients with Alzheimer's disease (AD), Down's syndrome (DS), cholestatic liver disease (CLD) and abetalipoproteinemia (ABL). The neuropathology of both AD and DS is thought to be related in part to oxidative stress. The diseases of AVED, of cholestatic liver disease, and of abetalipoproteinemia are thought to be due to lack of circulating tocopherol, leading to inadequate protection against oxidative damage. We demonstrate the presence of alpha-TTP in cerebellar Purkinje cells in patients having vitamin E deficiency states or diseases associated with oxidative stress.

Abetalipoproteinemia↗

PubMed1999

Prion diseases and the immune system.

Unlike other infectious diseases, transmissible spongiform encephalopathies elicit no specific immune response. Indeed, because the infectious agent, the prion, seems to be essentially composed of a protein with a primary structure identical to a host encoded protein, the lymphoid system is naturally tolerant. However, lymphoid organs are strongly implicated in the early peripheral steps of the disease. Paradoxically, immunodeficient animals, which are more susceptible to infections by usual pathogens, appear to be partially or completely resistant to experimental infection by prions by peripheral route. Several studies suggest that in normal subjects, cells of the immune system support the replication of prions and might allow their spreading from the periphery to the central nervous system. Thus, the lymphoid system appears to behave as a Trojan horse rather than a protective fortification in the process of prion infection. A greater understanding of the pathophysiology of these aspects of prion diseases could lead to immunomanipulation strategies aimed at preventing prion spread into the central nervous system, once peripheral exposure has occurred.

Animals↗

PubMed1998

A novel Polish presenilin-1 mutation (P117L) is associated with familial Alzheimer's disease and leads to death as early as the age of 28 years.

The majority of early-onset familial Alzheimer's disease (FAD) is associated with mutations in the presenilin-1 (PS1) gene. We describe a novel Polish PS1 mutation of Pro117Leu, associated with the earliest average age of onset and death so far reported in a PS-linked, FAD kindred. Human kidney 293 and mouse neuroblastoma N2a cells were stably transfected with wild-type and PS1 P117L. There was a significant increase in the amyloid beta42/40 ratio in the N2a P117L PS1 transfected cells compared with N2a transfected with wild-type PS1. What role PS has in the pathogenesis of AD remains to be determined, however, the severity of the clinical picture associated with this PS1 mutation stresses the importance of presenilin.

Adult↗

PubMed1998

Decreases in plasma A beta 1-40 levels with aging in non-demented elderly with ApoE-epsilon 4 allele.

This report examines plasma amyloid beta proteins A beta 40 and A beta 42 and apolipoprotein E (apoE) levels and their relationships with age in non-demented older adults with (N = 32) or without the apoE-epsilon 4 allele (N = 94). A beta levels did not differ between the groups whereas the epsilon 4 allele was associated with a significant reduction in plasma apoE. In subjects with the epsilon 4 allele, increasing age was associated with significant reduction in plasma A beta 40. Subjects without the epsilon 4 allele showed a significant positive correlation between A beta 40 and A beta 42 levels. There was also a significant correlation between plasma A beta 40 and apoE levels in all subjects.

Aging↗

PubMed1998

Alpha B-crystallin is associated with intermediate filaments in astrocytoma cells.

Alpha B-crystallin, a major protein of the vertebrate lens and a member of the small heat shock protein family, is expressed in non-lenticular tissues, including the central nervous system, where it is found mainly in glia. In Rosenthal fibers (RF), astrocytic inclusions that accumulate in Alexander's Disease, alpha B-crystallin is found with hsp27 and skeins of intermediate filaments (IF) of the GFAP and vimentin types. We have investigated the association between IF and alpha B-crystallin in a human astrocytoma cell line, U-373MG, which expresses alpha B-crystallin. Cytoskeletal preparations contained alpha B-crystallin, and a filamentous pattern in which alpha B-crystallin co-localized with GFAP and vimentin by double label immunofluorescence. Immuno-electronmicroscopy confirmed the localization to IF. GFAP isolated from bovine brain and re-assembled, was associated with alpha B-crystallin. Thus, a proportion of alpha B-crystallin in astroglia is associated with IF, and this association may be critical in the formation of RF.

Animals↗

PubMed1998

Enrichment of presenilin 1 peptides in neuronal large dense-core and somatodendritic clathrin-coated vesicles.

Presenilin 1 is an integral membrane protein specifically cleaved to yield an N-terminal and a C-terminal fragment, both membrane-associated. More than 40 presenilin 1 mutations have been linked to early-onset familial Alzheimer disease, although the mechanism by which these mutations induce the Alzheimer disease neuropathology is not clear. Presenilin 1 is expressed predominantly in neurons, suggesting that the familial Alzheimer disease mutants may compromise or change the neuronal function (s) of the wild-type protein. To elucidate the function of this protein, we studied its expression in neuronal vesicular systems using as models the chromaffin granules of the neuroendocrine chromaffin cells and the major categories of brain neuronal vesicles, including the small clear-core synaptic vesicles, the large dense-core vesicles, and the somatodendritic and nerve terminal clathrin-coated vesicles. Both the N- and C-terminal presenilin 1 proteolytic fragments were greatly enriched in chromaffin granule and neuronal large dense-core vesicle membranes, indicating that these fragments are targeted to these vesicles and may regulate the large dense-core vesicle-mediated secretion of neuropeptides and neurotransmitters at synaptic sites. The presenilin 1 fragments were also enriched in the somatodendritic clathrin-coated vesicle membranes, suggesting that they are targeted to the somatodendritic membrane, where they may regulate constitutive secretion and endocytosis. In contrast, these fragments were not enriched in the small clear-core synaptic vesicle or in the nerve terminal clathrin-coated vesicle membranes. Taken together, our data indicate that presenilin 1 proteolytic fragments are targeted to specific populations of neuronal vesicles where they may regulate vesicular function. Although full-length presenilin 1 was present in crude homogenates, it was not detected in any of the vesicles studied, indicating that, unlike the presenilin fragments, full-length protein may not have a vesicular function.

Animals↗

PubMed1998

Cell-type-specific enhancement of amyloid-beta deposition in a novel presenilin-1 mutation (P117L).

The presenilin-1 (PS1) gene mutation (Pro117Leu), recently identified in a Polish family is characterized by the earliest reported onset (from 24-31 years) of Alzheimer disease (AD) and a very short duration of disease (4-6 years). The neuropathology of 2 subjects with this PS1 mutation (ages at death: 35 and 37 years) was compared to four Down syndrome (DS) patients (mean age at death: 62 years) and 4 sporadic AD patients (mean age at death: 79 years with a mean duration of disease of 18 years). The Polish familial AD (FAD) patients showed a marked increase in the amyloid burden of 2 6-fold in most areas of the brain. The entorhinal cortex was an exception where the amyloid burden was similar in each category of patient. Some brain regions of the Polish FAD patients showed a massive increase of amyloid, such as the molecular layer of the cerebellum where a 7- and 25-fold increase was noted, compared with DS and sporadic AD patients respectively. The cerebellar vessel amyloid burden was also greatly increased in the FAD patients, reflecting a vascular compartment specific increase of amyloid beta deposition. The presence of this PS1 mutation has an even greater effect on both vascular and parenchymal amyloid deposition, than the overexpression of the amyloid beta precursor protein present in DS patients, suggesting that PS mutations can be a critical factor determining amyloid deposition.

Adult↗

PubMed1998

The prionoses and other conformational disorders.

The basic pathogenesis of numerous neurodegenerative disorders is now thought to be related to abnormal protein conformation. The common theme in all these diseases is the conversion of a normal cellular and/or circulating protein into an insoluble, aggregated, beta-sheet rich form which is deposited in the brain, sometimes in the form of amyloid. These deposits are toxic and produce neuronal dysfunction and death. The most common of these illnesses is Alzheimer's disease (AD), in which a central event is the conversion of the normal soluble amyloid beta (sA beta) peptide to amyloid beta (A beta) within neuritic plaques and cerebral vessels. A unique category of the conformational conditions are prion related diseases (or prionoses), where the etiology is thought to be related to conversion of the normal prion protein, PrPC, into an infectious and pathogenic form, PrPSc. In the case of AD and the prionoses, the conformational change can be influenced by the presence of mutations in various gene products, as well as by chaperone proteins. Apolipoprotein E is thought to act as such a chaperone protein in AD; however, among the prionoses such a protein has been hypothesized to exist only by indirect evidence and is called "protein X". Our growing understanding of the mechanisms involved in this category of diseases, raises the possibility of therapeutic approaches based directly on the prevention and reversal of pathologic protein conformation.

Alzheimer Disease↗

PubMed1998

Light and electron microscopic immunolocalization of presenilin 1 in abnormal muscle fibers of patients with sporadic inclusion-body myositis and autosomal-recessive inclusion-body myopathy.

Sporadic inclusion-body myositis (s-IBM) is the most common progressive muscle disease of older persons. The muscle biopsy demonstrates mononuclear cell inflammation and vacuolated muscle fibers containing paired helical filaments and 6- to 10-nm fibrils, both resembling those of Alzheimer disease brain and Congo red positivity. The term hereditary inclusion-body myopathies (h-IBMs) designates autosomal-recessive or autosomal-dominant disorders with muscle biopsies cytopathologically similar to s-IBM but without inflammation. Vacuolated muscle fibers of both s-IBM and the h-IBMs contain accumulations of several "Alzheimer-characteristic proteins" including beta-amyloid protein and beta-amyloid precursor protein, and their paired helical filaments are composed of phosphorylated tau. We used six well characterized antibodies against several residues of presenilin 1 (PS1) to immunostain muscle biopsies of 12 patients with s-IBM, 5 patients with autosomal-recessive inclusion-body myopathy, and 16 normal and disease controls. Seventy to eighty percent of the vacuolated muscle fibers of both s-IBM and autosomal-recessive inclusion-body myopathy had inclusions that were strongly PS1-immunoreactive, which by immunoelectron microscopy localized mainly to paired helical filaments and 6- to 10-nm filaments. None of the control biopsies had PS1-positive inclusions characteristic of the s- and h-IBM abnormal muscle fibers. Mutations of the newly discovered PS1 gene are responsible for early-onset familial Alzheimer disease (AD), and PS1 is abnormally accumulated in sporadic and familial AD brain. Our study provides the first demonstration of PS1 abnormality in non-neural tissue and in diseases other than AD and suggests that the cytopathogenesis in AD brain and IBM muscle may share similarities.

Adult↗

PubMed1997

Detection of apolipoprotein E/dimeric soluble amyloid beta complexes in Alzheimer's disease brain supernatants.

The inheritance of the apolipoprotein (apo) E4 allele is an important risk factor for late-onset Alzheimer's disease (AD). A major component of the Alzheimer's disease neuritic plaques is amyloid beta (A beta). We previously identified apoE/A beta complexes within neuritic plaques (1). It was not known if this interaction takes place before or after A beta peptides become incorporated into neuritic plaques. To address this question we sought evidence of apoE complexes with brain soluble A beta peptides in AD and control patients. In addition, numerous proteins have been shown to bind A beta peptides in vitro. It is not know if any of these bind brain sA beta in vivo. We found evidence for the presence of apoE/dimeric sA beta complexes in the AD brain and could not detect complexes with other A beta peptide binding proteins. The binding of sA beta to apoE may be one factor influencing its clearance from the brain and/or its conformational state.

Alzheimer Disease↗

PubMed1997

Alzheimer's soluble amyloid beta is a normal component of human urine.

Soluble A beta (Sa beta) is normally present at a low concentration in human plasma and cerebrospinal fluid. Although the factors involved in the regulation of Sa beta plasma levels are still unknown, we have explored its excretion in the urine as one of the possible homeostatic mechanisms. The presence of Sa beta in the urine was investigated via immunoprecipitation experiments with anti-A beta antibodies followed by detection and identification by immunoblot, MALDI mass spectrometry and sequence analysis. Soluble A beta (4.3 kDa) immunoreactivity was present in the urine of normal donors, Down's syndrome individuals as well as in patients with renal disorders exhibiting glomerular or mixed proteinuria. Edman degradation of the immunoprecipitated material yielded the intact A beta N-terminus and mass spectra analysis indicated the existence of a major component at mlz 4327, corresponding to the molecular mass of A beta1-40. Semiquantitative data obtained from the immunoprecipitation experiments indicate that under normal conditions the daily excretion of intact Sa beta in the urine represents less than 1% of the circulating pool.

Amyloid beta-Peptides↗

PubMed1997

Biology of A beta amyloid in Alzheimer's disease.

The genetic associations with the pathological features of AD are diverse: A rapidly growing number of mutations in presenilin 1 and 2 on chromosomes 14 and 1, respectively, are found in many early-onset FAD patients (Lendon et al., 1997). In addition, beta PP mutations are found in a small percentage of early-onset FAD kindreds. The apoE4 allele on chromosome 19 is associated with the presence of the most common form of AD, sporadic AD (Wisniewski & Frangione, 1992; Namba et al., 1991). However, it is clear that other proteins are also involved in the pathogenesis of AD, since some early-onset FAD kindreds do not have linkage to PS1, PS2, apoE, or beta PP, while at least 50% of late-onset AD is unrelated to apoE. Other proteins which have been implicated in the formation of senile plaques, but so far are not known to have any genetic linkage to AD, include proteoglycans (Snow et al., 1987), apoA1 (Wisniewski et al., 1995a), alpha 1-antichymotrypsin (Abraham et al., 1988), HB-GAM (Wisniewski et al., 1996a), complement components (McGeer & Rogers, 1992), acetylcholinesterase (Friede, 1965), and NAC (Ueda et al., 1993). Which of these proteins will be the most important for the etiology of the most common form of AD, late-onset sporadic AD, remains an open question. Three of the genes which are now known to be linked to AD, including PS1, beta PP, and apoE, have been established immunohistochemically and biochemically to be components of senile plaques (see Fig. 1). This raises at least two possibilities: either each of these proteins is part of one pathway with A beta-related amyloid formation as a final causative pathogenic event or amyloid deposition in AD is a reactive process related to dysfunction of a number of different CNS proteins. Whether or not amyloid formation is directly causative in the pathogenesis of AD, current data suggest that new therapeutic approaches which may inhibit the aggregation and/or the conformational change of sA beta to A beta fibrils (Soto et al., 1996) have the greatest likelihood to make a significant impact on controlling amyloid accumulation in AD.

Alzheimer Disease↗

PubMed1997

Presenilin-1 is associated with Alzheimer's disease amyloid.

Mutations in presenilin (PS)-1 and -2, located on chromosome 14 and 1 respectively, are the major association with early-onset familial Alzheimer's disease (FAD). FAD has also been linked to mutations in the amyloid beta precursor protein (beta PP), and the presence of the apolipoprotein E4 allele is a risk factor for late-onset AD. The role of PS in FAD and in sporadic AD is unclear. We previously reported the presence of a PS-1 carboxyl-terminal epitope in neuritic plaques (Wisniewski T, Palha JA, Ghiso J, Frangione B: S182 protein in Alzheimer's disease neuritic plaques. Lancet 1995, 346:1366). In the present study, we examined a number of biochemically different cerebral and systemic amyloidoses, finding the PS-1 carboxy epitope only in association with amyloid beta (A beta) lesions. We confirm the presence of this epitope ultrastructurally in neuritic plaques. In addition, biochemical and amino acid sequence data are presented for an association of the 18-kd carboxy fragment of PS-1 with neuritic plaques with a start at residue 300. Three of the proteins with linkage to AD have now been found as components of neuritic plaques. It remains to be determined whether all of these proteins are involved in the same or different pathological pathway(s) and which of these proteins is the most important for the common, late-onset form of AD.

Adult↗

PubMed1996

The "nonamyloidogenic" p3 fragment (amyloid beta17-42) is a major constituent of Down's syndrome cerebellar preamyloid.

Down's syndrome (DS) patients show accelerated Alzheimer's disease (AD) neuropathology, which consists of preamyloid lesions followed by the development of neuritic plaques and neurofibrillary tangles. The major constituents of preamyloid and neuritic plaques are amyloid beta (Abeta) peptides. Preamyloid lesions are defined as being Abeta immunoreactive lesions, which unlike neuritic plaque amyloid are Congo red-negative and largely nonfibrillar ultrastructurally. DS patients can develop extensive preamyloid deposits in the cerebellum, without neuritic plaques; hence, DS cerebellums are a source of relatively pure preamyloid. We biochemically characterized the composition of DS preamyloid and compared it to amyloid in the neuritic plaques and leptomeninges in the same patients. We found that Abeta17-42 or p3 is a major Abeta peptide of DS cerebellar preamyloid. This 26-residue peptide is also present in low quantities in neuritic plaques. We suggest that preamyloid can now be defined biochemically as lesions in which a major Abeta peptide is p3.

Alzheimer Disease↗

PubMed1996

Alzheimer's presenilin 1 gene expression in platelets and megakaryocytes. Identification of a novel splice variant.

The presenilin 1 (PS1) gene located on chromosome 14 has been linked with the majority of early-onset FAD. The normal biological role of PS1 as well as the mechanism by which mutations in PS1 cause FAD remains unknown. PS1 expression in platelets and the Dami megakaryocytic cell line was examined by Western blot analysis and RT-PCR. Using an anti-N-terminus PS1 antibody we detected PS1 immunoreactive bands of 44, 32 and 27 kDa in both cell types. After RT-PCR we observed that platelets and megakaryocytes carry at least four different PS1 transcripts. One of them is a novel PS1 splice variant that lacks the coding sequence for exon 10 resulting in a shorter 409 amino acid protein.

Alternative Splicing↗

PubMed1996

The interaction between apolipoprotein E and Alzheimer's amyloid beta-peptide is dependent on beta-peptide conformation.

An important feature of Alzheimer's disease (AD) is the cerebral deposition of amyloid. The main component of the amyloid is a 39-44-amino acid residue protein called amyloid beta (A beta), which also exists as a normal protein in biological fluids, known as soluble A beta. A major risk factor for late-onset AD is the inheritance of the apolipoprotein (apo) E4 isotype of apoE. How apoE is involved in the pathogenesis of AD is unclear; however, evidence exists for a direct apoE/A beta interaction. We and others have shown that apoE copurifies with A beta from AD amyloid plaques and that under certain in vitro conditions apoE promotes a beta-sheet structure in A beta peptides. Currently we document the high affinity binding of A beta peptides to both human recombinant apoE3 and -E4 with a KD of 20 nM. This interaction is greatly influenced by the conformational state of the A beta peptide used. Furthermore, we show that the fibril modulating effect of apoE is also influenced by the initial secondary structure of the A beta peptide. The preferential binding of apoE to A beta peptides with a beta-sheet conformation can in part explain the copurification of A beta and apoE from AD amyloid plaques.

Alzheimer Disease↗