Showing papers by "John Q. Trojanowski published in 1991"

A68: a major subunit of paired helical filaments and derivatized forms of normal Tau

Abstract: Putative Alzheimer disease (AD)-specific proteins (A68) were purified to homogeneity and shown to be major subunits of one form of paired helical filaments (PHFs). The amino acid sequence and immunological data indicate that the backbone of A68 is indistinguishable from that of the protein tau (tau), but A68 could be distinguished from normal human tau by the degree to which A68 was phosphorylated and by the specific residues in A68 that served as phosphate acceptors. The larger apparent relative molecular mass (Mr) of A68, compared to normal human tau, was attributed to abnormal phosphorylation of A68 because enzymatic dephosphorylation of A68 reduced its Mr to close to that of normal tau. Moreover, the LysSerProVal motif in normal human tau appeared to be an abnormal phosphorylation site in A68 because the Ser in this motif was a phosphate acceptor site in A68, but not in normal human tau. Thus, the major subunits of a class of PHFs are A68 proteins and the excessive or inappropriate phosphorylation of normal tau may change its apparent Mr, thus transforming tau into A68.

Abnormal expression of two microtubule-associated proteins (MAP2 and MAP5) in specific subfields of the hippocampal formation in schizophrenia

Abstract: A variety of cytoarchitectural disturbances have been described in limbic regions in postmortem studies of schizophrenia, many of which suggest a developmental disturbance of normal neuronal geometry. This geometry is established and maintained by elements of the neuronal cytoskeleton. Immunohistochemistry with a panel of 15 monoclonal antibodies was used to monitor the presence of neuronal cytoskeletal proteins in the hippocampal formations of six patients with schizophrenia, six normal controls, and six with neurodegenerative disorders. In five of the six subjects with schizophrenia, prominent and specific alterations were found in the distribution of two microtubule-associated proteins, MAP2 and MAP5, which were anatomically selective for the subiculum and entorhinal cortex. In contrast, the immunoreactivity of other cytoskeletal proteins (i.e., tau, tubulins, and selected neurofilament protein phosphoisoforms) was similar for all subjects. Defects in the expression of MAP2 and MAP5, two proteins that contribute to the establishment and maintenance of neuronal polarity, could underlie some of the cytoarchitectural abnormalities described in schizophrenia and impair signal transduction in the affected dendrites. The subiculum and entorhinal cortex interconnect the hippocampal formation with widespread cortices and subcortical nuclei and play important roles in higher cognitive functions. Hence, pathologic lesions that distort the polarized geometry of neurons could play a role in the emergence of aberrant behavior in schizophrenia.

Epitope map of neurofilament protein domains in cortical and peripheral nervous system Lewy bodies.

Abstract: A subset of demented elderly patients exhibit large numbers of cortical intraneuronal inclusions similar to the neurofilament (NF)-rich Lewy bodies (LB) found in pigmented subcortical neurons of patients with Parkinson's disease (PD). Because these cortical inclusions may contribute to the emergence of cognitive impairments in afflicted individuals, the authors mapped the distribution of NF epitopes in these so-called cortical LBs. This was done using ethanol-fixed tissues and a large library of monoclonal antibodies (MAbs) with well-characterized binding specificities to various regions of each NF triplet protein. Cortical LBs were examined by light, confocal, and electron microscopy, and they were compared with the subcortical LBs of PD and LBs in the peripheral nervous system (PNS). Monoclonal antibodies specific for the rod regions of each of the three NF subunits, or for phosphate-dependent and independent antigenic sites in the tail region of the high- (NF-H) and middle- (NF-M) molecular weight (Mr) NF subunits as well as other MAbs to the extreme COOH terminus of NF-L and NF-M or the head region of NF-M labeled a variable number of cortical LBs. Remarkably one of these anti-NF MAbs, RMO32, which recognized a phosphorylated epitope in the tail region of NF-M, immunolabeled nearly all cortical LBs, whereas each of the other anti-NF MAbs never labeled more than 10% of ubiquitin- or RMO32-positive cortical LBs. Further LBs in the PNS resembled those in the central nervous system (CNS) in their immunologic properties, and LBs in both sites were dominated by filamentous aggregates at the ultrastructural level. These findings suggest that NF proteins are profoundly altered during their incorporation into cortical and PNS LBs. Further the authors here identified immunologic and ultrastructural properties common to cortical LBs, PNS LBs, and classic substantia nigra LBs in PD. The accumulation of filamentous, perikaryal inclusions rich in NF proteins at diverse sites in the CNS and PNS of patients with a variety of neurodegenerative disorders suggests a widespread disruption of NF metabolism or transport.

Expression patterns of β‐amyloid precursor protein (β‐APP) in neural and nonneural human tissues from alzheimer's disease and control subjects

Abstract: Both neural and nonneural human tissues from patients with or without Alzheimer's disease (AD) were surveyed to detect the presence of the beta-amyloid protein and its precursors This was accomplished using polyclonal and monoclonal antibodies to epitopes in the 695 amino acid long beta-APP (ie, beta-APP695), as well as in related beta-APPs Immunoreactivity in beta-APP in brain was prominent in senile plaques, extraneuronal tangles, and neurons Outside the brain, beta-APP staining was seen in neurons and satellite glial cells of the dorsal root, enteric and trigeminal ganglia, the adeno- and neurohypophysis, megakaryocytes, and adrenal gland in samples from patients with AD and those without AD Western blots of neocortex revealed three major proteins with apparent molecular masses of 105, 115, and 125 kDa in the insoluble membrane-associated fractions, while two broad bands with a molecular weight centered at about 100 and 120 kDa were detected in soluble fractions In addition, the pituitary and adrenal glands as well as cardiac muscle revealed prominent immunobands in membrane-associated fractions Notably, other nonneural tissues were devoid of beta-APP immunoreactivity Thus, the beta-APPs are detectable only in a limited number of nonneural tissues Taken together, these data suggest that beta-APPs produced in the brain are sources of beta-APP peptides that accumulate as senile plaques in AD

Human olfactory epithelium in normal aging, Alzheimer's disease, and other neurodegenerative disorders.

Abstract: By use of immunohistochemistry, we characterized the molecular phenotype of human olfactory epithelial (OE) cells and assessed the nature of the dystrophic olfactory neurites described initially in Alzheimer's disease (AD) Keratin 8 was present in all classes of OE cells Sustentacular cells lacked other cell type specific polypeptides and were distinguished from neurons and basal cells because the latter two classes of OE cells expressed neural cell adhesion molecules (N-CAMs) and microtubule associated proteins (MAPs), ie, MAP5 Basal cells expressed nerve growth factor receptors (NGFRs), which distinguished them from olfactory neurons Unlike their perikarya, olfactory axons expressed vimentin and GAP-43, but not peripherin or neurofilament (NF) proteins Olfactory nerves were distinguished from other axons because the latter were positive for all three NF subunits and peripherin, in addition to vimentin and GAP-43 Dystrophic neurites in the OE were GAP-43 positive, but they also expressed proteins that were not detected in normal olfactory nerves (ie, synaptophysin, MAP2, tau, peripherin, NF proteins) Further, rare NF positive olfactory neurons gave rise to NF positive dystrophic neurites These neurites were present in all 11 AD cases, 11 of 14 subjects with other neurodegenerative diseases, and 6 of 8 neurologically normal adult controls, but no dystrophic neurites were seen in 9 fetal and neonatal cases We conclude that the molecular phenotype of different human OE cells is distinct and that dystrophic olfactory neurites occur very frequently in neurologically normal adults The relevance of these neurites to aging or specific disease processes remains speculative

Epitopes located in spatially separate domains of each neurofilament subunit are present in Parkinson's disease Lewy bodies.

Abstract: Subcortical Lewy bodies are the pathological hallmark of idiopathic Parkinson's disease. This study sought to determine the extent to which each neurofilament subunit [low (NF-L), mid (NF-M), or high (NF-H)] was present in Lewy bodies by using light, confocal, and electron microscopy. A battery of 37 antineurofilament antibodies, characterized as to subunit specificity, epitope domain, and phosphorylation status, was employed to probe substantia nigra Lewy bodies from 15 Parkinson's disease cases. All 37 antibodies labelled Lewy bodies. The epitopes recognized by these antibodies included those in the NF-L rod and tail domains; the NF-M head, rod, and tail domains, as well as epitopes within, and flanking, the multiphosphorylation repeat site; and the NF-H rod domain and multiphosphorylation repeat sites. With these probes, nearly the entire length of each subunit could be demonstrated in Lewy bodies. However, the staining pattern of the Lewy bodies suggested that the tail domains of NF-M and NF-H were present in the periphery of the Lewy body core and in the Lewy body corona, but they appeared to be altered or missing in the center of the Lewy body core. In contrast, the head domain of NF-M, the tail domain of NF-L, and the rod domains of all three subunits are present throughout the Lewy body. These results strongly suggest that the entire extent of each neurofilament subunit is found in Lewy bodies but that the neurofilament subunits may be altered during the processing of these filaments into Lewy bodies.

Molecular milestones that signal axonal maturation and the commitment of human spinal cord precursor cells to the neuronal or glial phenotype in development

Abstract: Insights into the programmatic induction of neuronal and glial genes during human embryogenesis have depended largely on extrapolations of data derived from experimental mammals. However, the assumptions upon which these extrapolations are based have not been rigorously tested. Indeed, practically no information is available even on the human counterparts of the relatively small subset of well-characterized, developmentally regulated neuron and glial specific genes of the mammalian CNS. Thus, the developmental programs upon which human neural embryogenesis are based remain largely undeciphered. We have addressed this problem in immunohistochemical studies conducted on 22 human fetal spinal cords with gestational ages (GAs) that ranged from 6 to 40 weeks by using monoclonal antibodies to several classes of neuron or glial specific polypeptides. These polypeptides included: representatives of four different types (Types I-IV) of intermediate filament proteins, i.e., vimentin filament protein (VFP), glial fibrillary acidic protein (GFAP), different phospho-isoforms of the high (NF-H), middle (NF-M), and low (NF-L) molecular weight (Mr) neurofilament (NF) subunits, both acidic and basic cytokeratin (CK) proteins; three different microtubule associated proteins (MAPs), i.e., MAP2, MAP5, and tau; two different synaptic or coated vesicle proteins, i.e., synaptophysin (SYP) and clathrin light chain B (LCb); an oligodendroglial specific protein, i.e., myelin basic protein (MBP); and a receptor for a CNS trophic factor, i.e., the nerve growth factor receptor (NGFR).(ABSTRACT TRUNCATED AT 400 WORDS)

Molecular features of hypothalamic plaques in Alzheimer's disease.

Abstract: The pathology of Alzheimer's disease (AD) involves subcortical as well as cortical structures The authors have used immunohistochemical methods to study the molecular composition of AD plaques in the hypothalamus In contrast to previous studies using histochemical methods, the authors observed large numbers of diffuse plaques in the AD hypothalamus labeled with an antiserum to the beta-amyloid, or A4 peptide, of the beta-amyloid precursor proteins (beta APPs), whereas A4-immunoreactive plaques were uncommon in the hypothalamus of patients without AD Unlike plaques in the cortex and hippocampus of AD patients, hypothalamic plaques did not contain epitopes corresponding to other regions of the beta APPs, nor did they contain tau-, neurofilament-, or microtubule-associated protein-reactive epitopes, and did not disrupt the neuropil or produce astrogliosis These findings demonstrate that there are substantial molecular and cellular differences in the pathologic features of AD in the hypothalamus compared with those observed in hippocampal and cortical structures, which may provide insight into the pathogenetic mechanisms of AD

Neuroectodermal tumors of the peripheral and the central nervous system share neuroendocrine N-CAM-related antigens with small cell lung carcinomas.

Abstract: The current study describes the presence of neuroendocrine antigens of peripheral and central neural tumors using eight monoclonal antibodies raised to small cell lung carcinoma (SCLC), which recognize "neural/neuroendocrine" or "neural" antigens, as defined by their reaction pattern in normal tissues and tumors. At least five of them recognize different epitopes of the neural cell adhesion molecule (N-CAM). It was found that all of 12 neuroblastomas, 2 ganglioneuroblastomas and 4 ganglioneuromas as well as 23 central primitive neuroectodermal tumors, 13 astrocytomas and 4 ependymomas share "neural/neuroendocrine" antigens (as defined by the anti-N-CAM antibodies Moc-1, -21, -32, -52 and -191) with SCLC. The "neural/neuroendocrine" antigen defined by Moc-171 was also found in all peripheral tumors, but only in further differentiated central tumors. Non-N-CAM related "neural" antigens (as defined by Moc-51 and -172) were found only in better-differentiated peripheral and central tumors, but they could be demonstrated in all three medulloblastoma cell lines studied. In addition, the antigen defined by Moc-51 was demonstrated in an immunoblot of a neuroblastoma cell line. Antibodies recognizing "epithelial" antigens of SCLC and other epithelia and their tumors (Moc-31 and -181) were non-reactive. It was concluded that these findings give further support for a relation between neural and neuroendocrine tumors and that some of the antibodies may be useful for the detection of differentiation in neural tumors. Antibodies with an "epithelial" recognition pattern may serve to distinguish neural from neuroendocrine tumors.

Nerve growth factor receptor expression in peripheral and central neuroectodermal tumors, other pediatric brain tumors, and during development of the adrenal gland.

Abstract: Nerve growth factor (NGF) is important to the survival, development, and differentiation of neurons. Its action is mediated by a specific cell surface transmembrane glycoprotein, nerve growth factor receptor (NGFR). In this study, NGFR expression by human fetal and adult adrenal medullary tissue, peripheral nervous system (PNS) neuroectodermal tumors (neuroblastoma, ganglioneuroblastoma, ganglioneuroma), pediatric primitive neuroectodermal tumors (PNETs) of the central nervous system (CNS), and CNS gliomas was examined by an immunohistochemical technique. Sixty-nine tumors in total were probed in this manner. Nerve growth factor receptor immunoreactivity was confined to nerve fibers and clusters of primitive-appearing cells in the fetal adrenal, and to nerve fibers and ganglion cells of the adult adrenal medulla; adrenal chromaffin cells were negative. In PNS neuroectodermal tumors, there was NGFR expression in tumor cells of 6 of 11 neuroblastomas and 6 of 6 ganglioneuroblastomas or ganglioneuromas. Thirteen of thirty-five CNS PNETs showed NGFR positivity. In most CNS PNETs, NGFR was restricted to scattered single or small groups of cells, but two tumors with astroglial differentiation showed much more extensive immunoreactivity. Most astrocytomas (11 of 14) and all ependymomas (3 of 3) were intensely NGFR positive.

Vulnerability of the neuronal cytoskeleton in aging and Alzheimer disease: widespread involvement of all three major filament systems.

Abstract: Alzheimer disease (AD) is the commonest cause of dementia in the elderly (for recent reviews, see Chiu, 1989; Henderson & Finch, 1989; Katzman et al., 1988). As a consequence of the increasing number of people living beyond the seventh decade, AD has become the fourth leading cause of death in the United States. Despite the recognition of AD and the brain pathology associated with it more than 80 years ago (Alzheimer, 1907), the pathogenesis and etiology of AD remain enigmatic. Several reasons account for this such as (1) the complexity and limited understanding of the central nervous system (CNS); (2) an incomplete definition of AD and variants thereof; (3) the lack of animal models for hypothesis testing; (4) overlap between early AD and normal aging as well as between AD and other neurodegenerative diseases. For example, patients with idiopathic Parkinson disease (PD) frequently develop cognitive impairments, AD patients often exhibit extrapyramidal signs, and diminished olfaction is observed in AD and PD subjects (Chiu, 1989; Doty et al., 1987, 1989).