bromochloroacetic-acid and Alzheimer-Disease

Mallory bodies (MBs) are characteristic morphologic features of alcoholic hepatitis but are also associated with non-alcoholic liver diseases including long lasting cholestasis, metabolic and neoplastic disorders. MBs contain in addition to keratins non-keratin components, including microtubule-associated (tau protein) and other not yet characterized proteins in an aggregated form. Aggregation of these components in the cell is promoted by posttranslational modifications, such as partial proteolysis, phosphorylation and cross-linking, and may result in functional and structural disturbances of the cell depending on the physiologic function of the components involved. Several enzymes responsible for these modifications are Ca(++)-dependent. Thus, disturbance of Ca(++)-homeostasis may play an essential role in the pathogenesis of MBs. In some structural aspects MBs closely resemble inclusions associated with degenerative disorders of the central nervous system, including Alzheimer's and Parkinson's disease. Studies on the pathogenesis of MBs, therefore, not only shed light on a peculiar type of liver cell injury but may also assist in the understanding of other chronic degenerative diseases, particularly those of the central nervous system.

Topics: Alzheimer Disease; Animals; Brain Diseases; Calcium; Homeostasis; Humans; Keratins; Liver; Liver Cirrhosis, Alcoholic; Liver Diseases; Liver Diseases, Alcoholic; Parkinson Disease; Protein Processing, Post-Translational; Transcription, Genetic

Misfolded and aggregated proteins are a characteristic feature of a variety of chronic diseases. Examples include neurofibrillary tangles in Alzheimer disease, Lewy bodies in Parkinson disease and Mallory bodies (MBs) in chronic liver diseases, particularly alcoholic and non-alcoholic steatohepatitis (ASH and NASH). MB formation is at least in part the result of chronic oxidative cell stress in hepatocytes and can be induced in mice by long-term intoxication with 3,5-diethoxycarbonyl-1,4-dihydrocollidine (DDC). Proteomic analysis revealed that MBs consist of ubiquitinated keratins and the stress proteins Hsp70, Hsp25, and p62. Furthermore, marked overexpression of clusterin, which shares functional properties with small heat shock proteins, was identified by gene expression profiling of DDC-treated mice livers. To investigate whether clusterin has a function in the stress response to misfolded keratins, we performed transfection studies utilizing expression constructs encoding ubiquitin, p62, Hsp27, clusterin, keratin 8, and keratin 18. Ubiquitin was found in a strong and constant association with keratin aggregates, whereas binding of p62 to keratin was variable. Hsp27 did not colocalize with keratin aggregates under these experimental conditions. In contrast, clusterin associated with misfolded keratin only if its signal peptide was deleted and its secretion inhibited. This suggests that clusterin has ability to bind misfolded proteins, including keratins but its physiological function is restricted to the extracellular space. The extracellular localization of clusterin was underlined by immunohistochemical studies in Alzheimer disease brains, where clusterin was constantly found in association with amyloid plaques; in contrast, cytoplasmic inclusions such as neurofibrillary tangles as well as MBs in ASH were negative. Furthermore, we found clusterin in association with elastic fibers in the extracellular matrix in several chronic liver diseases, including ASH and alpha1-antitrypsin deficiency, implying a possible role of clusterin in liver fibrosis.

Topics: Adaptor Proteins, Signal Transducing; Alzheimer Disease; Animals; CHO Cells; Clusterin; Cricetinae; Cricetulus; Glycoproteins; Heat-Shock Proteins; HSP27 Heat-Shock Proteins; Humans; Immunohistochemistry; Keratins; Liver Diseases, Alcoholic; Mice; Molecular Chaperones; Neoplasm Proteins; Protein Folding; Sequestosome-1 Protein; Ubiquitin

Serum antibodies against a series of antigens, including an organ-specific central nervous system (CNS) antigen and the neurotransmitter serotonin, were investigated in 22 patients with Alzheimer's Disease (n=15) and other age-related dementias (n=7) by indirect immunofluorescence assay and enzyme-linked immunosorbent assay. Patients with dementia showed an increase of antibody-positive sera against nuclear antigen, gastric parietal cells, CNS antigen, gangliosides (Gm1), laminin, and keratin. Alzheimer's Disease patients alone exhibited antibodies against CNS antigen. However, the results do not show sufficient specificity and sensitivity for use as a diagnostic indicator.

Topics: Aged; Alzheimer Disease; Autoantibodies; Dementia, Multi-Infarct; Enzyme-Linked Immunosorbent Assay; Female; Fluorescent Antibody Technique, Direct; G(M1) Ganglioside; History, Ancient; Humans; Keratins; Laminin; Male; Serotonin

The earliest expression of truncated desmin in transfected PtK2 cells results in the formation of dispersed microprecipitates containing not only the truncated desmin, but also endogenous vimentin and cytokeratin proteins. Desmin microprecipitates without vimentin or vimentin microprecipitates without desmin are not observed. The microprecipitates involving cytokeratin invariably are also positive for desmin and vimentin. Over time, the precipitates enlarge into 1- to 2-microns spheroids and then fuse into amorphous chimeric juxtanuclear masses that can occupy > 30% of the cell volume. Concurrently, first the vimentin and then the cytokeratin networks are resorbed. The chimeric precipitates are not recognized or marked for degradation by the lysosomal system. Ultimately the cell nucleus fragments and the cell dies. Similar protein complexes appear in many human and animal pathologies, suggesting that a similar protein-precipitation sequence initiated by the introduction of a mutationally or environmentally altered protein molecule is at work.

Topics: Alzheimer Disease; Amyotrophic Lateral Sclerosis; Animals; Cell Nucleus; Cells, Cultured; Chemical Precipitation; Desmin; Intermediate Filaments; Keratins; Macropodidae; Vimentin

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), i.e., 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 (i.e., 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.

Topics: Adult; Aged; Aging; Alzheimer Disease; Cell Adhesion Molecules, Neuronal; Epithelial Cells; Epithelium; Female; Humans; Immunohistochemistry; Infant; Infant, Newborn; Infant, Premature; Keratins; Male; Microscopy, Electron; Microtubule-Associated Proteins; Middle Aged; Nerve Growth Factors; Nervous System Diseases; Neurites; Olfactory Mucosa; Receptors, Cell Surface; Receptors, Nerve Growth Factor; Vimentin

Antisera to microtubule-enriched fraction from normal human brain (anti-MT sera) label neurofibrillary tangles and neurites of neuritic (senile) plaques in brain sections of cases with Alzheimer disease/senile dementia of the Alzheimer type (AD/SDAT); the plaque core amyloid is not labeled. These anti-MT sera label both tangles in tissue sections and smears of isolated tangles which had been extracted with sodium dodecyl sulfate (SDS) to remove impurities trapped in between the paired helical filaments (PHF). The tangle labeling of anti-MT sera is eliminated on their absorption both with microtubule-enriched fractions from human and animal brain and with the isolated PHF. Neurofilament triplet, actin, myosin, keratin, or fibroblasts do not absorb the tangles staining antibodies. Furthermore, antisera containing antibodies to tubulin, microtubule-associated high mol. wt. polypeptides (MAPS), neurofilament triplet, and the 50,000 mol. wt. contaminant of CNS neurofilament preparations do not label tangles. On immunoblots of SDS-polyacrylamide gels of isolated PHF anti-MT sera label some of the same polypeptides identified with antisera to PHF; affinity-purified antibodies to tubulin used as a control do not label any PHF polypeptide on the immunoblots. The anti-MT sera, when preabsorbed with the PHF polypeptides eluted from SDS-polyacrylamide gels, do not label tangles. These studies demonstrate that a polypeptide/s cross-reactive with Alzheimer PHF is indeed normally present in brain and that it is different from tubulin, neurofilament triplet, actin, myosin, vimentin, and keratin.

Topics: Actins; Aged; Alzheimer Disease; Brain; Cross Reactions; Cytoskeleton; Electrophoresis, Polyacrylamide Gel; Humans; Immunoenzyme Techniques; Intermediate Filament Proteins; Keratins; Microtubule-Associated Proteins; Microtubules; Molecular Weight; Myosins; Neurofibrils; Neurofilament Proteins; Peptides; Tubulin