Ubiquitin is a common factor in intermediate filament inclusion bodies of diverse type in man, including those of Parkinson's disease, Pick's disease, and Alzheimer's disease, as well as Rosenthal fibres in cerebellar astrocytomas, cytoplasmic bodies in muscle, and mallory bodies in alcoholic liver disease

A rhodopsin mutant linked to autosomal dominant retinitis pigmentosa is prone to aggregate and interacts with the ubiquitin proteasome system

The inherited retinal degenerations are typified by retinitis pigmentosa (RP), a heterogeneous group of inherited disorders that causes the destruction of photoreceptor cells, the retinal pigmented epithelium, and choroid. This group of blinding conditions affects over 1.5 million persons worldwide. Approximately 30-40% of human autosomal dominant (AD) RP is caused by dominantly inherited missense mutations in the rhodopsin gene. Here we show that P23H, the most frequent RP mutation in American patients, renders rhodopsin extremely prone to form high molecular weight oligomeric species in the cytoplasm of transfected cells. Aggregated P23H accumulates in aggresomes, which are pericentriolar inclusion bodies that require an intact microtubule cytoskeleton to form. Using fluorescence resonance energy transfer (FRET), we observe that P23H aggregates in the cytoplasm even at extremely low expression levels. Our data show that the P23H mutation destabilizes the protein and targets it for degradation by the ubiquitin proteasome system. P23H is stabilized by proteasome inhibitors and by co-expression of a dominant negative form of ubiquitin. We show that expression of P23H, but not wild-type rhodopsin, results in a generalized impairment of the ubiquitin proteasome system, suggesting a mechanism for photoreceptor degeneration that links RP to a broad class of neurodegenerative diseases.

Mallory body--a disease-associated type of sequestosome

Mallory bodies (MBs) consist of abnormal keratins, ubiquitin, heat shock proteins, and the protein p62. p62 is encoded by an immediate-early response gene that rapidly responds to a variety of extracellular signals involved in cell proliferation, differentiation, and particularly oxidative stress. It acts as an adapter in signal transduction and binds noncovalently to ubiquitin, possibly being involved in the regulation of the fate of ubiquitinated proteins by segregation (i.e., sequestosome or aggresome formation). The presence of p62 together with ubiquitinated abnormal keratins in the MB characterizes MBs as a disease-associated type of sequestosome. A detailed study on the expression of p62 and its relationship to MB formation in the 3,5-diethoxycarbonyl-1,4-dihydrocollidine (DDC)-treated mouse liver is reported based on immunohistochemical, immunoblot, and Northern blot analyses. The results indicate that p62 is rapidly induced in hepatocytes of intoxicated animals preceding MB formation. As suggested by experiments with short-term DDC-treated naive mice and mice refed DDC after recovery from long-term DDC treatment (primed mice), p62 does not exert an initiating effect on MB formation but the appearance of MBs requires the presence of abnormal keratins, which associate with p62 after ubiquitination. The rapid induction of p62 and its association with MBs further support the role of oxidative stress in MB formation. In conclusion, the constant presence of p62 in MBs suggests that binding of p62 to abnormal keratins may allow hepatocytes to dispose potentially harmful proteins in a biologically inert manner.

Coexpression and accumulation of ubiquitin +1 and ZZ proteins in livers of children with alpha(1)-antitrypsin deficiency

The ZZ variant of alpha(1)-antitrypsin deficiency (AATD) is well known to cause liver damage and cirrhosis in some affected children. Ubiquitin abnormality was recently shown to be significant in AATD in childhood cirrhosis. Molecular misreading (MM), defined as faulty transcription of genomic information from DNA into mRNA, as well as its translation into mutant proteins, has been documented in many pathologic processes where aggregation of abnormal proteins occurs. The misread protein, ubiquitin-B(+1) (UBB(+1)), was recently identified in the hallmarks of various neurological disorders. The objective of this study was to determine whether MM of ubiquitin occurs in AATD. Twelve explanted liver specimens from AATD-affected children with cirrhosis were retrieved from archival sources, along with 10 control liver specimens obtained from autopsies of age-matched children with no clinical, gross anatomic, or histologic evidence of liver disease. Double immunofluorescence studies using rabbit polyclonal antibodies against UBB(+1) and AAT were performed on consecutively sectioned tissue. UBB(+1) immunoreactivity was colocalized with AAT in all cirrhotic AATD livers. The control livers were consistently negative. Ubiquitin MM is prominent in AATD-affected cirrhotic livers. This indicates that for children with AATD and cirrhosis, ubiquitin MM is a necessary cofactor to the aggregation of mutant ZZ isoform of AATD.

p62 Is a common component of cytoplasmic inclusions in protein aggregation diseases

Exposure of cells to stress, particularly oxidative stress, leads to misfolding of proteins and, if they are not refolded or degraded, to cytoplasmic protein aggregates. Protein aggregates are characteristic features of a variety of chronic toxic and degenerative diseases, such as Mallory bodies (MBs) in hepatocytes in alcoholic and non-alcoholic steatohepatitis, neurofibrillary tangles in neurons in Alzheimer's, and Lewy bodies in Parkinson's disease. Using 2D gel electrophoresis and mass spectrometry, we identified p62 as a novel MB component. p62 and cytokeratins (CKs) are major MB constituents; HSP 70, HSP 25, and ubiquitinated CKs are also present. These proteins characterize MBs as a prototype of disease-associated cytoplasmic inclusions generated by stress-induced protein misfolding. As revealed by transfection of tissue culture cells overexpressed p62 did not induce aggregation of regular CK filaments but selectively bound to misfolded and ubiquitinated CKs. The general role of p62 in the cellular response to misfolded proteins was substantiated by detection of p62 in other cytoplasmic inclusions, such as neurofibrillary tangles, Lewy bodies, Rosenthal fibers, intracytoplasmic hyaline bodies in hepatocellular carcinoma, and alpha1-antitrypsin aggregates. The presence of p62 along with other stress proteins and ubiquitin in cytoplasmic inclusions indicates deposition as aggregates as a third line of defense against misfolded proteins in addition to refolding and degradation.

The ubiquitin-proteasome system and its role in ethanol-induced disorders

Some of the most fundamental yet important cellular activities such as cell division and gene expression are controlled by short-lived regulatory proteins. The levels of these proteins are controlled by their rates of degradation. Similarly, protein catabolism plays a crucial role in prolonging cellular life by destroying damaged proteins that are potentially cytotoxic. A major player in these catabolic reactions is the ubiquitin-proteasome system, a novel proteolytic system that has become the primary proteolytic pathway in eukaryotic cells. Ubiquitin-mediated proteolysis is now regarded as the major pathway by which most intracellular proteins are destroyed. Equally important, from a toxicological standpoint, is that the ubiquitin-proteasome system is also widely considered to be a cellular defense mechanism, since it is involved in the removal of damaged proteins generated by adduct formation and oxidative stress. This review describes the history and the components of the ubiquitin-proteasome system, its regulation and its role in pathological states, with the major emphasis on ethanol-induced organ injury. The available literature cited here deals mainly with the effects of ethanol consumption on the ubiquitin-proteasome pathway in the liver. However, since this proteolytic system is an essential pathway in all cells it is an attractive experimental model and therapeutic target in extrahepatic organs such as the brain and heart that are also affected by excessive alcohol consumption.

Ubiquitinated granular structures and initial neurofibrillary changes in the human brain

Ubiquitin-positive dots and granular structures from insular, temporopolar, hippocampal and parahippocampal cortices of nondemented and Alzheimer's disease patients have been studied with both light and electron microscopes. The relationship of both types of ubiquitin-positive elements with pretangle neurons and neurofibrillary tangles has been analyzed by comparing adjacent or nearly adjacent sections immunostained for either ubiquitin or an antibody that recognizes hyperphosphorylated tau protein (AT-8). Moreover, a double protocol with both antibodies was used in order to obtain double-stained sections. The presence of ubiquitin-positive dots and granular structures precedes the appearance of pretangle neurons in the youngest cases. In aged and Alzheimer disease cases, both types of ubiquitin-positive elements decrease in number as pretangle neurons are replaced by mature and ghost tangles. Ultrastructurally, dots and granular structures appear to be degenerating neuronal processes and/or terminals. Our results suggest that the degeneration of these processes and/or terminals might be related with the initiation of neurofibrillary degeneration.

Ubiquitin and the molecular pathology of neurodegenerative diseases

Ubiquitin plays a central role in normal cellular function as well as in disease. It is possible to group ubiquitin-immunostained structures into several main groups, the most distinctive being the ubiquitin/intermediate filament/alphaB crystallin family of inclusions that seem to represent a general cellular response to abnormal proteins recently termed the aggresomal response. While ubiquitin immunohistochemistry is a very useful technique for detecting pathological changes and inclusion bodies in the nervous system this alone is not enough to classify inclusions, and a panel of antibodies is recommended to clarify any findings made by screening tissues with anti-ubiquitin. Several mechanistic possibilities now exist to explain the accumulation of ubiquitinated proteins in cells of the nervous system, understanding of which should lead to new therapeutic advances in the group of chronic neurodegenerative diseases.

Molecular pathways involved in the neurotoxicity of 6-OHDA, dopamine and MPTP: contribution to the apoptotic theory in Parkinson's disease

Parkinson's disease (PD) is a neurodegenerative disorder characterized by a preferential loss of the dopaminergic neurons of the substantia nigra pars compacta. Although the etiology of PD is unknown, major biochemical processes such as oxidative stress and mitochondrial inhibition are largely described. However, despite these findings, the actual therapeutics are essentially symptomatical and are not able to block the degenerative process. Recent histological studies performed on brains from PD patients suggest that nigral cell death could be apoptotic. However, since post-mortem studies do not allow precise determination of the sequence of events leading to this apoptotic cell death, the molecular pathways involved in this process have been essentially studied on experimental models reproducing the human disease. These latter are created by using neurotoxic compounds such as 6-hydroxydopamine (6-OHDA), 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) or dopamine (DA). Extensive study of these models have shown that they mimick, in vitro and in vivo, the histological and/or the biochemical characteristics of PD and thus help to define important cellular actors of cell death presumably critical for the nigral degeneration. This review reports recent data concerning the biochemical and molecular apoptotic mechanisms underlying the experimental models of PD and correlates them to the phenomena occurring in human disease.

Expression of stress proteins alpha B-crystallin, ubiquitin, and hsp27 in pallido-nigral spheroids of aged rhesus monkeys

Ubiquitin and alpha B-crystallin belong to a class of proteins which are overexpressed in a variety of human neuropathological conditions associated with increased cellular stress. In this study we have examined the brains of aged rhesus monkeys (Macaca mulatta; n = 10, mean age: 29.7 years) using antibodies against the stress proteins ubiquitin, alpha B-crystallin, and heat shock protein 27 (hsp27). Here, we demonstrate an increased expression of ubiquitin, alpha B-crystallin, and hsp27 in spheroid bodies predominantly localized in the globus pallidus and pars reticulata of the substantia nigra. A portion of the pallido-nigral spheroids also contained ferric iron as highlighted by Perls' staining. On the basis of these findings we advance the hypothesis that expression of ubiquitin, alpha B-crystallin, and hsp27 in pallido-nigral spheroids of aged rhesus monkeys represents a stress response possibly related to increased iron-mediated oxidative stress.

The ubiquitin protein catabolic disorders

The ubiquitin-proteasome system of intracellular proteolysis is essential for cell viability. We propose the concept that neurodegenerative diseases such as Alzheimer's and Parkinson's, as well as other conditions including some types of cancer, collectively represent a raft of 'ubiquitin protein catabolic disorders' in which altered function of the ubiquitin-proteasome system can cause or directly contribute to disease pathogenesis. Genetic abnormalities within the ubiquitin pathway, either in ubiquitin-ligase (E3) enzymes or in deubiquitinating enzymes, cause disease because of problems associated with substrate recognition or supply of free ubiquitin, respectively. In some cases, mutations in protein substrates of the ubiquitin-proteasome system may directly contribute to disease progression because of inefficient substrate recognition. Mutations in transcripts for the ubiquitin protein itself (as a result of 'molecular misreading') also affect ubiquitin-dependent proteolysis with catastrophic consequences. This has been shown in Alzheimer's disease and could apply to other age-associated neurodegenerative conditions. Within the nervous system, accumulation of unwanted proteins as a result of defective ubiquitin-dependent proteolysis may contribute to aggregation events, which underlie the pathogenesis of several major human neurodegenerative diseases.

Sequence of events in the assembly of Mallory body components in mouse liver: clues to the pathogenesis and significance of Mallory body formation

BACKGROUND/AIMS

Chronic intoxication of mice with 3,5-diethoxycarbonyl-1,4-dihydrocollidine (DDC) or griseofulvin (GF) results in appearance of Mallory bodies (MBs) and alterations of the keratin cytoskeleton, which are reversible upon drug withdrawal but recur after readministration within 2-3 days.

METHODS

DDC- or GF-treated and recovered mice were reintoxicated with the original drugs but also colchicine and lumicolchicine. Cytoskeletal alterations of hepatocytes and MB formation were monitored by immunofluorescence microscopy using keratin, MB-specific antibodies, antibodies to phosphoepitopes and to HSP70. Keratin 8/18 mRNA expression and protein levels were determined by competitive reverse transcription-polymerase chain reaction, in situ-hybridization and western blotting.

RESULTS

Duration of pretreatment was important for the efficiency of MB triggering. Rapid increase of keratin 8/18 mRNA and proteins was found in all reintoxicated mice concomitant with MB formation, whereby keratin 8 prevailed over keratin 18. Keratins and a protein with heat shock characteristics (M(M) 120-1 antigen) were the earliest detectable MB components, whereas ubiquitination and phosphorylation followed later.

CONCLUSIONS

Overproduction of keratins is a major but not the only step responsible for MB formation. Additional components (e.g. M(M) 120-1 antigen) and excess of keratin 8 over keratin 18 are essential.

Increased levels of oxidative stress markers detected in the brains of mice devoid of prion protein

Although minor abnormalities have been reported in prion protein (PrP) knock-out (Prnp-/-) mice, the normal physiological function of PrP, the causative agent implicated in transmissible spongiform encephalopathies (TSE), remains unresolved. Since there are increasing correlations between oxidative stress and amyloidoses, we decided to investigate whether PrP plays a role in oxidative modulation. We found higher levels of oxidative damage to proteins and lipids in the brain lysates of Prnp-/- as compared to wild-type (WT) mice of the same genetic background. These two indicators, protein oxidation and lipid peroxidation, are hallmarks of cellular oxidative damage. Elevated levels of ubiquitin-protein conjugates were also observed in Prnp-/- mice, a probable consequence of cellular attempts to remove the damaged proteins as indicated by increased proteasome activity. Taken together, these findings are indicative of a role for PrP in oxidative homeostasis in vivo.

Ubiquitin as a marker of cell injury in nonalcoholic steatohepatitis

Ubiquitin (UB), an intracellular protein that binds to other proteins to target them for proteolysis, is associated with Mallory hyalin (MH), which supports a biopsy diagnosis of nonalcoholic steatohepatitis (NASH). We analyzed 54 liver biopsy specimens from 49 patients with a clinical diagnosis of NASH for immunoreactive UB and multiple features of necroinflammation, fibrosis, and Prussian blue-positive iron to determine whether the presence of immunoreactive UB increases detection of MH or correlates with other features of cell injury or mutations of the HFE gene. MH and UB were graded. Analysis for HFE gene mutations was performed in 48 patients. Biopsy diagnoses were distributed as follows: NASH, 42; steatosis, 10; and nonspecific changes, 2. UB was present in 20 specimens and MH in 23. Of 31 specimens with 0 MH, 6 had UB; of 14 with 1 + (questionable) MH, 7 had 1+ or 2+ UB. UB correlated positively and significantly with the diagnosis and grade of NASH, presence of MH, cell swelling, lobular inflammation, and fibrosis. Immunostaining for UB may enhance detection of MH in questionable cases, support the diagnosis of NASH, and indicate which patients may be at risk for progression of disease.

Prevention of beta-amyloid neurotoxicity by blockade of the ubiquitin-proteasome proteolytic pathway

In many neurodegenerative disorders, such as Alzheimer's disease, inclusions containing ubiquitinated proteins have been found in the brain, suggesting a pathophysiological role for ubiquitin-mediated proteasomal degradation of neuronal proteins. Here we show for the first time that the beta-amyloid fragment 1-40, which in micromolar levels causes the death of cortical neurons, also induces the ubiquitination of several neuronal proteins. Prevention of ubiquitination and inhibition of proteasome activity block the neurotoxic effect of beta-amyloid. These data suggest that beta-amyloid neurotoxicity may cause toxicity through the activation of protein degradation via the ubiquitin-proteasome pathway. These findings suggest possible new pharmacological targets for the prophylaxis and/or treatment of Alzheimer's disease and possibly for other related neurodegenerative disorders.

Role of the proteasome in Alzheimer's disease

The proteasome is a multicatalytic complex involved in the degradation of polyubiquitinated proteins. Here we review the clues of a possible involvement of the proteasome in Alzheimer's disease neuropathology. Thus, we discuss the fact that the proteasome modulates the intracellular concentrations of presenilins 1 and 2. These two proteins, when mutated, appear responsible for most of early onset forms of Alzheimer's disease and this is thought to be due to the exacerbation of the pathogenic pathway of the maturation of the beta-amyloid precursor protein. Controlling presenilins concentrations could have drastic repercussions on cell physiology as suggested by the fact that proteasome inhibitors drastically potentiate the 'normal' or 'pathogenic' presenilins phenotype related with betaAPP processing. The possibility of considering the proteasome as a potential target for therapeutic intervention in Alzheimer's disease is discussed.

Differential impairment of 20S and 26S proteasome activities in human hematopoietic K562 cells during oxidative stress

The 20S proteasome and the 26S proteasome are major components of the cytosolic and nuclear proteasomal proteolytic systems. Since proteins are known to be highly susceptible targets for reactive oxygen species, the effect of H(2)O(2) treatment of K562 human hematopoietic cells toward the activities of 20S and 26S proteasomes was investigated. While the ATP-independent degradation of the fluorogenic peptide suc-LLVY-MCA was not affected by H(2)O(2) concentrations of up to 5 mM, the ATP-stimulated degradation of suc-LLVY-MCA by the 26S proteasome began to decline at 400 microM and was completely abolished at 1 mM oxidant treatment. A combination of nondenaturing electrophoresis and Western blotting let us believe that the high oxidant susceptibility of the 26S proteasome is due to oxidation of essential amino acids in the proteasome activator PA 700 which mediates the ATP-dependent proteolysis of the 26S-proteasome. The activity of the 26S-proteasome could be recovered within 24 h after exposure of cells to 1 mM H(2)O(2) but not after 2 mM H(2)O(2). In view of the specific functions of the 26S proteasome in cell cycle control and other important physiological functions, the consequences of the higher susceptibility of this protease toward oxidative stress needs to be considered.

Keratins turn over by ubiquitination in a phosphorylation-modulated fashion

Keratin polypeptides 8 and 18 (K8/18) are intermediate filament (IF) proteins that are expressed in glandular epithelia. Although the mechanism of keratin turnover is poorly understood, caspase-mediated degradation of type I keratins occurs during apoptosis and the proteasome pathway has been indirectly implicated in keratin turnover based on colocalization of keratin-ubiquitin antibody staining. Here we show that K8 and K18 are ubiquitinated based on cotransfection of His-tagged ubiquitin and human K8 and/or K18 cDNAs, followed by purification of ubiquitinated proteins and immunoblotting with keratin antibodies. Transfection of K8 or K18 alone yields higher levels of keratin ubiquitination as compared with cotransfection of K8/18, likely due to stabilization of the keratin heteropolymer. Most of the ubiquitinated species partition with the noncytosolic keratin fraction. Proteasome inhibition stabilizes K8 and K18 turnover, and is associated with accumulation of phosphorylated keratins, which indicates that although keratins are stable they still turnover. Analysis of K8 and K18 ubiquitination and degradation showed that K8 phosphorylation contributes to its stabilization. Our results provide direct evidence for K8 and K18 ubiquitination, in a phosphorylation modulated fashion, as a mechanism for regulating their turnover and suggest that other IF proteins could undergo similar regulation. These and other data offer a model that links keratin ubiquitination and hyperphosphorylation that, in turn, are associated with Mallory body deposits in a variety of liver diseases.

Cytokeratin 8 protects from hepatotoxicity, and its ratio to cytokeratin 18 determines the ability of hepatocytes to form Mallory bodies

In alcoholic hepatitis, a severe form of alcohol-induced toxic liver injury, as well as in experimental intoxication of mice with the porphyrinogenic drugs griseofulvin and 3,5-diethoxycarbonyl-1, 4-dihydrocollidine, hepatocytes form cytoplasmic protein aggregates (Mallory bodies; MBs) containing cytokeratins (CKs) and non-CK components. Here we report that mice lacking the CK8 gene and hence CK intermediate filaments in hepatocytes, but still expressing the type I partner, ie, the CK18 gene, do not form MBs but suffer from extensive porphyria and progressive toxic liver damage, leading to the death of a considerable number of animals (7 of 12 during 12 weeks of intoxication). Our observations show that 1) in the absence of CK8 as well as in the situation of a relative excess of CK18 over CK8 no MBs are formed; 2) the loss of CK8 is not compensated by other type II CKs; and 3) porphyria and toxic liver damage are drastically enhanced in the absence of CK8. Our results point to a protective role of CKs in certain types of toxic liver injury and suggest that MBs by themselves are not harmful to hepatocytes but may be considered as a product of a novel defense mechanism in hepatocytes.

Relative sensitivity of undifferentiated and cyclic adenosine 3',5'-monophosphate-induced differentiated neuroblastoma cells to cyclosporin A: potential role of beta-amyloid and ubiquitin in neurotoxicity

Cyclosporin A is routinely used in transplant therapy following allogeneic or xenogeneic tissue transplantation to prevent rejection. This immunosuppressive drug is also neurotoxic; however, its mechanisms of action for neurotoxicity are poorly understood. Undifferentiated and cyclic adenosine 3',5'-monophosphate (cAMP)-induced differentiated neuroblastoma (NB) cells were used as an experimental model to study the toxicity of cyclosporin A. Results showed that cyclosporin A promoted the outgrowth of neurites and inhibited the growth of undifferentiated NB cells. When cyclosporin A was added simultaneously with RO20-1724, an inhibitor of cyclic nucleotide phosphodiesterase, or with prostaglandin E1, a stimulator of adenylate cyclase, it markedly enhanced the growth inhibitory and differentiation effects of these cAMP-stimulating agents. In addition, cyclosporin A added to cAMP-induced differentiated NB cells caused dose-dependent degeneration of these cells as evidenced by the vacuolization of cytoplasm and the fragmentation of nuclear and cytoplasmic materials; however, neurites remained intact. Cyclosporin A alone did not alter the intensity of cell immunostaining for ubiquitin or beta-amyloid peptide (amino acids 1-14) (Abeta1-14); however, it enhanced the intensity of staining for both ubiquitin and Abeta in cells that were treated with cAMP-stimulating agents. The intensity of staining of amyloid precursor protein (amino acids 44-63) (APP44-66) did not change in any treated group, suggesting that the increase in Abeta staining is due to increased processing of APP to Abeta. We propose that one of the mechanisms of cyclosporin A-induced neurotoxicity involves increased levels of Abeta and ubiquitin.

Degradation of alpha-synuclein by proteasome

Mutations in alpha-synuclein are known to be associated with Parkinson's disease (PD). The coexistence of this neuronal protein with ubiquitin and proteasome subunits in Lewy bodies in sporadic disease suggests that alterations of alpha-synuclein catabolism may contribute to the pathogenesis of PD. The degradation pathway of alpha-synuclein has not been identified nor has the kinetics of this process been described. We investigated the degradation kinetics of both wild-type and A53T mutant 6XHis-tagged alpha-synuclein in transiently transfected SH-SY5Y cells. Degradation of both isoforms followed first-order kinetics over 24 h as monitored by the pulse-chase method. However, the t((1)/(2)) of mutant alpha-synuclein was 50% longer than that of the wild-type protein (p < 0.01). The degradation of both recombinant proteins and endogenous alpha-synuclein in these cells was blocked by the selective proteasome inhibitor beta-lactone (40 microM), indicating that both wild-type and A53T mutant alpha-synuclein are degraded by the ubiquitin-proteasome pathway. The slower degradation of mutant alpha-synuclein provides a kinetic basis for its intracellular accumulation, thus favoring its aggregation.

Stains for the differential diagnosis of degenerative dementias

Our understanding of the structural substrates underlying the dementia syndrome has been transformed by the introduction of the Gallyas silver stain and the application of immunostains for tau, ubiquitin, and alpha-synuclein. Visualization of sequential changes in Alzheimer's disease and the recognition of a new substrate for dementia and dementia with argyrophilic grains, are two of the advances related to the application of the Gallyas method. The specificity of alpha-synuclein for recognizing Lewy bodies enables the unequivocal diagnosis of dementia with Lewy bodies. The diverse entities that constitute the Pick complex can be identified by applying immunostains for tau and ubiquitin in addition to the Gallyas silver stain.

Unique characteristics of ubiquitin-bonded complex play a pathological role in dentatorubral-pallidoluysian atrophy

Abnormal complex formation of dentatorubral-pallidoluysian atrophy (DRPLA) protein and pathological ubiquitination of abnormal complex are two pathological processes involved in DRPLA neurodegeneration. Pathological ubiquitination and solubility in SDS and reducing agent are two unique characteristics of the DRPLA protein complex. Ubiquitination of abnormal DRPLA protein complex in DRPLA brain tissue is heat-resistant and stronger than that in control brain tissue. Pathological ubiquitination of DRPLA protein complex correlates with the onset of symptoms and the size of an expanded glutamine repeat in brain tissue of patients with DRPLA. Pathological ubiquitination plays an important role in DRPLA pathology. DRPLA protein complex is water-insoluble but soluble in SDS and reducing agent, and displays no difference in water insolubility between control and DRPLA brain tissue. Abnormal insoluble complex formation is not developed by a qualitative change in water insolubility of DRPLA protein complex but is developed by a spontaneous accumulation of an abnormally large amount of the DRPLA protein complex.

Abnormal dentatorubral-pallidoluysian atrophy (DRPLA) protein complex is pathologically ubiquitinated in DRPLA brains

Dentatorubral-pallidoluysian atrophy (DRPLA) is caused by expansion of a glutamine repeat in DRPLA protein. DRPLA protein undergoes greater complex formation in DRPLA brain tissue, and expanded glutamine repeat enhances complex formation of DRPLA protein. Immunoblots with and without reduction show that the DRPLA protein complex is ubiquitinated only in DRPLA brain tissue. Moreover, immunoblots of regional DRPLA brain tissues reveal that pathological ubiquitination of DRPLA protein complex is found selectively in affected lesions. Double-labeling immunohistochemical studies with antibodies against DRPLA protein and ubiquitin demonstrate that the DRPLA protein is co-localized with ubiquitin in DRPLA neurons and show characteristic neuronal cytoplasmic inclusions with ubiquitinated DRPLA protein complex in the center. Our findings suggest that DRPLA protein undergoes abnormal complex formation with expanded glutamine repeat, and then the complex is pathologically ubiquitinated in DRPLA brain tissue. Pathological ubiquitination of abnormal DRPLA protein complex plays a role in DRPLA pathology.

Analysis of intracytoplasmic hyaline bodies in a hepatocellular carcinoma. Demonstration of p62 as major constituent

Intracytoplasmic hyaline bodies (IHBs) resemble inclusions in hepatocellular carcinoma cells, which so far have escaped further characterization. A relationship to Mallory bodies was suggested on the basis of light microscopy and filamentous ultrastructure. A hepatocellular carcinoma containing numerous IHBs was studied. Our studies revealed immunoreactivity of IHBs with the monoclonal antibodies SMI 31 and MPM-2, which recognize hyperphosphorylated epitopes present on paired helical filaments in Alzheimer's disease brains (SMI 31) or on diverse proteins hyperphosphorylated by mitotic kinases in the M-phase of the cell cycle (MPM-2). One- and two-dimensional gel electrophoresis of tumor extracts followed by immunoblotting with SMI 31 and MPM-2 antibodies revealed a major immunoreactive protein with an apparent molecular weight between 62 and 65 kd, which was resolved into several highly acidic (pH 4.5) protein components in two-dimensional gels. This protein was undetectable in non-neoplastic liver tissue. Sequence analysis identified the SMI 31 and MPM-2 immunoreactive material as p62, indicating that p62 is a major constituent of IHBs. p62 is an only recently discovered protein that is a phosphotyrosine-independent ligand of the SH2 domain of p56(lck), a member of the c-src family of cytoplasmic kinases. Moreover, p62 binds ubiquitin and may act as an adapter linking ubiquitinated species to other proteins. These features suggest a role of p62 in signal transduction and possibly also carcinogenesis. IHBs observed in the hepatocellular carcinoma cells presented are the first indications of a role of p62 in disease.

Early expression of ubiquitin in myofibers of rats in organophosphate intoxication

The degenerative process of the myofibers of the diaphragm of rats intoxicated with the organophosphate isofenphos, a compound that inhibits esterases, was studied at different intervals of intoxication. Early disorganization of the intermyofibrillar network and of the myofilaments, as well as dilatation of organelles, were observed by use of transmission electron microscopy. These changes precede macrophage invasion of the muscle fibers. Early expression of ubiquitin was observed in segments of muscle fibers by immunohistochemistry. Bands of polyubiquitin complexes in muscle homogenates were observed by immunoblotting. These bands disappeared in later stages of intoxication. A 42.5-kDa band corresponds to actin, as observed by immunoblotting using antisarcometric actin. This indicates relatively large amounts of polyubiquitin complex associated with sarcomeric actin in muscle fibers in early stages of intoxication. Based on these results it seems that actin is an important target in organophosphate-induced myofiber degradation and that the degradation of this protein-by the polyubiquitin pathway-may play an important role in the early disorganization of the sarcomere, as observed by electron microscopy. A possible role of the ubiquitin proteolytic pathway is that of trying to eliminate proteins modified in the early phases of muscle fiber degeneration, which is a necessary step for regeneration of the posterior segmental muscle.

Lewy body dementia

Although Lewy body dementia (LBD) has received a considerable amount of interest in the last decade, there still exists a certain level of confusion concerning the clinical and neuropathological features associated with this disorder. According to many researchers, LBD represents a distinct dementing illness with specific clinical features. The neuropathological hallmark for this disorder is the Lewy body, a spherical intraneuronal cytoplasmic inclusion originally described in brainstem nuclei in Parkinson's disease. In LBD, Lewy bodies are found in subcortical nuclei, such as the substantia nigra, as well as diffusely in the neocortex. Recently, a consortium on dementia with Lewy bodies was held that established consensus guidelines for the clinical and pathological diagnosis of LBD. This review will focus on the newest developments in LBD, addressing specifically clinical and neuropathological features, diagnostic classification, genetics and potential pharmacotherapy.

Formation of GFAP cytoplasmic inclusions in astrocytes and their disaggregation by alphaB-crystallin

In several neuropathological conditions, alphaB-crystallin and glial fibrillary acidic protein (GFAP) accumulate and form cytoplasmic inclusions in astrocytes. To explore the pathogenesis of the inclusions and the possible functions of the accumulated alphaB-crystallin, GFAP and alphaB-crystallin were overexpressed in cultured astrocytes by transient transfection. Human GFAP formed filamentous, cytoplasmic inclusions in mouse astrocytes, NIH3T3 cells, rat C6 glioma cells, and human U251 glioma cells. These human GFAP inclusions did not contain the endogenous vimentin or beta-tubulin, and the intermediate filament and microtubular networks of the transfected cells appeared normal. alphaB-crystallin and hsp25 were associated with the GFAP inclusions. Increasing intracellular alphaB-crystallin levels using recombinant adenoviruses, either before or after GFAP inclusions were formed, decreased the number of inclusion-bearing astrocytes and converted the human GFAP from an inclusion to a spread, filamentous form. These results suggest that alphaB-crystallin reorganizes abnormal intermediate filament aggregates into the normal filamentous network.

Serum ubiquitin levels in patients with alcoholic liver disease

Serum concentrations of free ubiquitin and multiubiquitin chain as determined by immunoassays were compared between 10 healthy subjects, and 11 patients with alcoholic hepatic fibrosis, 10 with alcoholic cirrhosis, and 6 with viral liver cirrhosis. All measurements of multiubiquitin chains were expressed in terms of a standard multiubiquitin chain reference preparation 1. Serum concentrations (mean +/- SD) of free ubiquitin and multiubiquitin chains were significantly higher in patients with alcoholic cirrhosis (63.5 +/- 33.7 ng/ml and 7.5 +/- 4.6 ng/ml) than in the normal subjects (29.6 +/- 6.6 ng/ml, p < 0.05 and 4.1 +/- 1.7 ng/ml, p < 0.05), and those with alcoholic hepatic fibrosis (34.8 +/- 16.3 ng/ml, p < 0.05 and 3.0 +/- 0.7 ng/ml, p < 0.05) and viral liver cirrhosis (28.8 +/- 7.5 ng/ml, p < 0.05 and 4.2 +/- 1.3 ng/ml, p < 0.05). Serum levels of both forms of ubiquitin in six patients with alcoholic cirrhosis showed a tendency to decline after 3 months of abstinence. In a total of 14 patients with alcoholic liver damage, 11 with brain atrophy had significantly higher serum levels of both ubiquitin forms than did three patients without brain atrophy (p < 0.05). No correlation was seen between serum concentrations of either form of ubiquitin and liver function test results in the patients with alcoholic liver damage. However, serum levels of both forms of ubiquitin levels correlated significantly with cumulative alcohol intake (p < 0.05). A significant correlation (p < 0.05) also was observed between serum levels of multiubiquitin chains and mean corpuscular volume, a marker of alcohol consumption. These results suggest that the serum concentrations of ubiquitin, especially multiubiquitin chain is a good marker for the diagnosis of alcoholic cirrhosis.

Altered microtubule-associated tau messenger RNA isoform expression in livers of griseofulvin- and 3,5-diethoxycarbonyl-1, 4-dihydrocollidine-treated mice

Tau proteins belong to the family of microtubule-associated proteins (MAPs), which so far have been mostly detected in neuronal cells. Different domains on the protein serve different functions. By alternative splicing, several mRNAs and tau isoforms are created from one gene, which contain these functionally important domains to various degrees, and thus differ in their microtubule-related properties. In the present article, several novel observations are reported. Tau mRNA and proteins have been identified and further characterized in mouse liver. It is shown on the basis of mRNA determinations that at least three tau isoforms differing particularly with respect to their amino-terminal domains are present in mouse liver. The major and predominant isoform (isoform 1) lacks portions encoded by exons 2 and 3, which are responsible for cross-talk of microtubules with their environment ("projection domain"). Moreover, mRNA encoding tau protein with four repeats of the microtubule binding domain predominate in embryonal as well as adult mouse liver in contrast to brain, in which a shift from the predominant three-repeat isoform to the four-repeat isoform characterizes the transition from the embryonic to the adult stage. Intoxication with griseofulvin (GF) or 3,5-diethoxycarbonyl-1, 4-dihydrocollidine (DDC) significantly affects in a reversible manner the levels of tau mRNA as well as isoform ratios in mouse liver, but not in mouse brain. Tau mRNAs are significantly increased in intoxicated mouse livers. Moreover, a shift to isoform 1 lacking exons 2 and 3 occurs. However, the increase in liver tau protein was less than expected from increased mRNA levels, which could be the result of translational or posttranslational regulation. The consequences on microtubular function are as yet unclear, but impairment can be expected because the overexpressed tau mRNA isoform lacks the domain that mediates interaction of microtubules with their environment. On the other hand, the ratio of polymerized (microtubules) to nonpolymerized tubulin remained unaffected.

Ubiquitin, cellular inclusions and their role in neurodegeneration

Covalent binding of ubiquitin to proteins marks them for degradation by the ubiquitin/ATP-dependent pathway. This pathway plays a major role in the breakdown of abnormal proteins that result from oxidative stress, neurotoxicity and mutations. Failure to eliminate ubiquitinated proteins disrupts cellular homeostasis, causing degeneration. Inclusions containing ubiquitinated proteins are commonly detected in many neurological disorders. These aggregates are mostly cytosolic; nevertheless, ubiquitinated inclusions are found in endosomes/lysosomes in Alzheimer's disease and prion encephalopathies, and in nuclei in disorders associated with CAG/polyglutamine repeats, such as Huntington's disease and spinocerebellar ataxias. Ubiquitinated aggregates must result from a malfunction or overload of the ubiquitin/ATP-dependent pathway or from structural changes in the protein substrates, halting their degradation. Prevention of protein aggregation in these diseases might offer new therapeutic leads.

Calorie restriction, stress and the ubiquitin-dependent pathway in mouse livers

Calorie restriction (R) is the only known method to delay the aging process and extend mean and maximal lifespan in rodents. R has been shown to delay the age-related accumulation of damaged proteins and to protect organisms from various stresses which can produce damaged proteins. Such stresses include irradiation, heat shock, and oxidative stress. The ubiquitin- and ATP-dependent proteolytic pathway (UPP) has been associated with the degradation of abnormal and/or damaged proteins. We examined the effect of diet and oxidative stress on activities of the UPP in supernatants from livers taken from 23-month-old Emory mice which had been exposed to an in-vivo injection of paraquat. Paraquat induces oxidative stress by generating superoxide radicals. In livers from non-stressed animals, steady-state levels of endogenous ubiquitin conjugates, de novo conjugate formation, and E1 and E2 activities were significantly lower in R animals than in control (C) animals. However, after exposure to paraquat, levels of endogenous ubiquitin conjugates were significantly higher in R versus C animals, and de novo conjugate formation and E1 and E2 activities in R animals rose to levels which were indistinguishable from levels of these activities noted in C animals. R was associated with an increased ability to degrade beta-lactoglobulin by the UPP after an oxidative stress was imposed. Ability to degrade beta-lactoglobulin by the C or R livers in non-stressed animals was not significantly different. Taken together, these data indicate that oxidative stress in R animals is associated with enhanced levels of ubiquitin conjugates and that this enhancement may be due to an increase in UPP activity. These data also indicate that the ability to form ubiquitin conjugates and the UPP system does not change with oxidative stress in C animals. The latter is consistent with prior reports that suggests that older C animals may already be in a state of enhanced oxidative stress and that activities of the UPP provide a sensitive indicator of levels of cellular redox status.

Dementia with Lewy bodies

In the last decade, a new degenerative dementia, probably the second most common after Alzheimer's disease (AD), has been increasingly recognized under the consensus name of dementia with Lewy bodies (DLB). This article reviews current clinical, genetic, and pathological DLB data and indicates directions for future research. DLB overlaps in clinical, pathological, and genetic features with AD and Parkinson's disease (PD). Clinically, it is characterized by progressive cognitive impairment with significant fluctuations in alertness, parkinsonism, and psychosis with recurrent hallucinations. The neuropathological hallmarks are the intracytoplasmic inclusions in substantia nigra typical of PD, known as Lewy bodies (LB) but distributed widely throughout paralimbic and neocortical regions. Most of the cases also coexist with a plaque predominant AD. It is probably the unique and differential distribution of the lesions throughout cortical and subcortical structures in each of these disorders that supports a specific clinical syndrome and may ultimately prove most useful in understanding their different etiologies. Several genes have recently been implicated in LB formation. Special interest arises from mutations in the alpha-synuclein gene, which appears to be responsible for autosomal dominant PD in several kindreds. This gene encodes a presynaptic protein, a fragment of which is present in AD plaques. Recent studies show intense and quite specific alpha-synuclein immunoreactivity in LB and related neurites, suggesting a potential role of this protein in the aggregation or precipitation of LB inclusions.

Immunohistochemical assessment of constitutive and inducible heat-shock protein 70 and ubiquitin in human cerebellum and caudate nucleus

The distributions of constitutive and inducible 70-kDa heatshock proteins (Hsc70 and Hsp70, respectively) and ubiquitin (Ub) were investigated in autopsy specimens from 24 adult human brains. The objectives were to verify that the milder fixation and celloidin embedding applied to those specimens preserved protein immunoreactivity in the tissue sections, even with extended intervals between death and fixation, and to determine the typical pattern of distribution of the proteins in aged human cerebellum and caudate nucleus. To achieve these objectives, the patterns of immunoreactivity in human specimens were compared with those in normal rat brain after three methods of immersion fixation: 1. 1% Formalin; 2. 10% Formalin; 3. Methacarn (a modification of Carnoy's solution). Additionally, some rats were left refrigerated, but unfixed for up to 24 h to mimic the postmortem interval that commonly occurs prior to fixation of human autopsy material. Tissues were embedded in celloidin, sectioned at 100 microns, and the celloidin dissolved to permit immunostaining. Immunoreactivity for all antigens was greatly diminished in the rat brain by fixation in 10% formalin compared to 1% formalin or methacarn. Rat and human brain tissues fixed in the latter two solutions showed similar patterns of low levels of Hsp70 immunostaining in gray matter and other areas where neuronal somata were concentrated, whereas Hsc70 immunostaining was much greater in those same areas. Little Hsc70 or Hsp70 immunoreactivity was detected in the white matter from either source, but immunoblots of human gray and white matter suggested that white matter contained more Hsc70 and Hsp70 than apparent by tissue section immunoreactivity. Ubiquitin immunostaining in rat and human brain showed the same high levels as Hsc70 in gray matter, but unlike Hsc70, was also visible in white matter. These patterns remained the same in rat brains even if fixation was delayed for 24 h. In three human brain specimens, elevated Hsc70 staining, but not Hsp70 or Ub, was found in a ring pattern similar to that described as the ischemic penumbra in experimentally induced brain ischemia. These results indicated that dilute formalin preserved Hsc/Hsp70 and Ub antigenicity well, and that the proteins had similar distributions in human and rat brains, despite the extended postmortem delay in fixation of the former. They also suggested that evidence of premortem, localized cellular metabolic stress may be preserved in the postmortem human brain by an alteration in the typical distribution of Hsc70.

alpha-Synuclein in filamentous inclusions of Lewy bodies from Parkinson's disease and dementia with lewy bodies

Lewy bodies and Lewy neurites are the defining neuropathological characteristics of Parkinson's disease and dementia with Lewy bodies. They are made of abnormal filamentous assemblies of unknown composition. We show here that Lewy bodies and Lewy neurites from Parkinson's disease and dementia with Lewy bodies are stained strongly by antibodies directed against amino-terminal and carboxyl-terminal sequences of alpha-synuclein, showing the presence of full-length or close to full-length alpha-synuclein. The number of alpha-synuclein-stained structures exceeded that immunoreactive for ubiquitin, which is currently the most sensitive marker of Lewy bodies and Lewy neurites. Staining for alpha-synuclein thus will replace staining for ubiquitin as the preferred method for detecting Lewy bodies and Lewy neurites. We have isolated Lewy body filaments by a method used for the extraction of paired helical filaments from Alzheimer's disease brain. By immunoelectron microscopy, extracted filaments were labeled strongly by anti-alpha-synuclein antibodies. The morphologies of the 5- to 10-nm filaments and their staining characteristics suggest that extended alpha-synuclein molecules run parallel to the filament axis and that the filaments are polar structures. These findings indicate that alpha-synuclein forms the major filamentous component of Lewy bodies and Lewy neurites.

Dementia with Lewy bodies. A distinct non-Alzheimer dementia syndrome?

Lewy body formation is central to the pathological phenotype of a spectrum of disorders. The most familiar of these is the extrapyramidal syndrome of idiopathic Lewy-body Parkinson's disease (PD). Studies of dementia in the elderly suggest that another manifestation of Lewy body pathology is equally or more common than Parkinson's disease. This syndrome of Dementia with Lewy bodies (DLB) has been given a number of diagnostic labels and is characterised by dementia, relatively mild parkinsonism, visual hallucinations, and fluctuations in conscious level. Although many of these features can arise in Parkinson's disease, the patients with DLB tend to have early neuropsychiatric features which predominate the clinical picture, and the diagnosis of the syndrome in practice is more concerned with the differential diagnosis of Alzheimer's disease (AD). Distinction from AD has clinical importance because of potentially differing therapeutic implications. Diagnostic guidelines for the clinical diagnosis and pathological evaluation of DLB are reviewed. Research into the disorder has centered around characterising the clinical, neuropsychological, pathological, neurochemical and genetic relationships with Alzheimer's disease on the one hand, and Parkinson's disease on the other. Many cases of DLB have prominent pathological features of AD and there are some shared genetic risk factors. Differences from the pathology of PD are predominantly quantitative rather than qualitative and evidence is discussed which suggests that DLB represents a clinicopathological syndrome within the spectrum of Lewy body disorders. The possibility that the syndrome represents a chance association of PD and AD is not supported by published studies.

Aging, calorie restriction and ubiquitin-dependent proteolysis in the livers of Emory mice

Calorie restriction (R), the only known method to delay the aging process and extend mean and maximal lifespan, has been shown to delay the age-related decline in protein degradation. There are several proteolytic pathways. The ubiquitin- and ATP-dependent proteolytic pathway (UPP) is frequently associated with degradation of damaged abnormal and/or regulatory proteins. We examined the effect of aging and R on supernatants of livers taken from young (4.5 months) and old (23 months) Emory mice. Aging was associated with increased levels of endogenous ubiquitin conjugates, enhanced ability to form high molecular weight conjugates and ubiquitin activating (E1) and ubiquitin conjugating (E2) activity in the control (C) liver supernatants. The age-related increase in levels of endogenous ubiquitin conjugates in liver appears to be primarily due to increased E1 and E2 activities. R prevented the age-related increase in E1 and E2 activity, and thus prevented the age-related increase in levels of ubiquitin conjugates. In spite of the age-related increase in ubiquitin conjugates, no age-related changes in ubiquitin-dependent proteolytic pathway were observed in the C animals. R was associated with an enhanced ability (130%) to degrade beta-lactoglobulin by the ubiquitin-dependent proteolytic pathway in livers from 4.5-month-old animals relative to age-matched C livers. However, rates of the ubiquitin-dependent degradation of beta-lactoglobulin in the 23-month-old C and R animals were indistinguishable. There were no age- or diet-related differences in the ability to degrade another substrate, oxidized ribonuclease (RNase).

Prostaglandins act as neurotoxin for differentiated neuroblastoma cells in culture and increase levels of ubiquitin and beta-amyloid

Although chronic inflammatory reactions have been proposed to cause neuronal degeneration associated with Alzheimer's disease (AD), the role of prostaglandins (PGs), one of the secretory products of inflammatory reactions, in degeneration of nerve cells has not been studied. Our initial observation that PGE1-induced differentiated neuroblastoma (NB) cells degenerate in vitro more rapidly than those induced by RO20-1724, an inhibitor of cyclic nucleotide phosphodiesterase, has led us to postulate that PGs act as a neurotoxin. This study has further investigated the effects of PGs on differentiated NB cells in culture. Results showed that PGA1 was more effective than PGE1 in causing degeneration of differentiated NB cells as shown by the cytoplasmic vacuolation and fragmentation of soma, nuclei, and neurites. Because increased levels of ubiquitin and beta-amyloid have been implicated in causing neuronal degeneration, we studied the effects of PGs on the levels of these proteins during degeneration of NB cells in vitro by an immunostaining technique, using primary antibodies to ubiquitin and beta-amyloid. Results showed that PGs increased the intracellular levels of ubiquitin and beta-amyloid prior to degeneration, whereas the degenerated NB cells had negligible levels of these proteins. These data suggest that PGs act as external neurotoxic signals which increase levels of ubiquitin and beta-amyloid that represent one of the intracellular signals for initiating degeneration of nerve cells.

Aging and the nigro-striatal pathway

Aging is associated with a progressive impairment in motor function. This feature, together with the decline in mental function, could be considered as an aging syndrome which may finally compromise the ability of the elderly to maintain an active, independent life-style. In the present paper a wide variety of morphological aspects, which have been classically related to brain aging and others such as cytoskeletal changes, the role of growth factors and molecular changes, will be reviewed focusing on aging of the nigrostriatal pathway. In addition to sharing features of aging common to other structures, it is likely that the nigrostriatal pathway has specific characteristics derived from its particular molecular characteristics and/or from a selective vulnerability to aging. To gain further insight into the aging syndrome, the acquisition of rigorous criteria for selecting control cases is paramount. The improvement of methods for the preservation of human tissue is also crucial.

Neurofibrillary lesions in experimental aluminum-induced encephalopathy and Alzheimer's disease share immunoreactivity for amyloid precursor protein, A beta, alpha 1-antichymotrypsin and ubiquitin-protein conjugates

Neurofibrillary tangles of Alzheimer's disease contain predominantly tau protein and to a lesser degree amyloid precursor protein (APP), A beta protein, alpha 1-antichymotrypsin (ACT) and ubiquitin. Previously we have demonstrated the presence of phosphorylated tau and neurofilament proteins in neurofibrillary degeneration (NFD) induced by aluminum (Al) maltolate in rabbits [Savory et al., Brain Res. 669 (1995) 325-329; Savory et al., Brain Res. 707 (1996) 272-281]. Using the same animal system we have now detected APP, A beta, ACT and ubiquitin-like immunoreactivities in NFD-bearing neurons, often colocalizing in the NFD. Diffuse cytoplasmic staining for APP, A beta and ubiquitin was also present in neurons without NFD from Al maltolate-treated rabbits. This study provides additional support for immunochemical similarities between Al-induced NFD in rabbits and the neurofibrillary tangles in human subjects with Alzheimer's disease.

Monoclonal antibodies to purified cortical Lewy bodies recognize the mid-size neurofilament subunit

Lewy bodies (LBs) are filamentous intraneuronal inclusions that are hallmark lesions of Parkinson's disease, and LBs have been shown, by immunohistochemistry, to contain cytoskeletal as well as other cellular proteins. Similar LBs also occur in the cortical neurons of a subset of patients with Alzheimer's disease (AD), and cortical LBs are the predominant or sole lesions in the brains of patients with an AD-like dementia known as diffuse Lewy-body disease (DLBD). To gain insight into the biochemical composition of LBs, we generated monoclonal antibodies (mAbs) to LBs purified from the brains of patients with DLBD. Here, we describe three of these new mAbs (LB48, LB202, and LB204) that stained LBs by immunohistochemistry and recognized the medium molecular mass neurofilament (NF) protein in western blots. These results support the hypothesis that NF subunits are integral components of LBs. Continued efforts to clarify the composition of LBs are likely to lead to novel strategies for the antemortem diagnosis of LB disorders as well as to insight into the role LBs play in the degeneration of affected neurons in these disorders.

Spheroid body myopathy revisited

Having reported spheroid body myopathy from Indiana (IN) inherited in an autosomal-dominant fashion several years ago, we now describe additional findings from the Oregon branch--briefly recorded earlier--and confirm earlier studies in another clinically affected IN member of this kinship demonstrating identical spheroid bodies within the myopathic muscle specimens. The spheroid bodies also contained increased amounts of desmin, alpha-B crystallin, and ubiquitin within muscle fibers. Our studies now have established that spheroid body myopathy is a member of the growing family of desminopathic neuromuscular conditions.

Toxic effects of griseofulvin: disease models, mechanisms, and risk assessment

Griseofulvin (GF) has been in use for more than 30 years as a pharmaceutical drug in humans for the treatment of dermatomycoses. Animal studies give clear evidence that it causes a variety of acute and chronic toxic effects, including liver and thyroid cancer in rodents, abnormal germ cell maturation, teratogenicity, and embroyotoxicity in various species. No sufficient data from human studies are available at present to exclude a risk in humans: therefore, attempts were made to elucidate the mechanisms responsible for the toxic effects of GF and to address the question whether such effects might occur in humans undergoing GF therapy. It is well documented that GF acts as a spindle poison and its reproductive toxicity as well as the induction of numerical chromosome aberrations and of micronuclei in somatic cells possibly may result from disturbance of microtubuli formation. Likewise, a causal relationship between aneuploidy and cancer has been repeatedly postulated. However, a critical survey of the data available on aneuploidogenic chemicals revealed insufficient evidence for such an association. Conceivably, other mechanisms may be responsible for the carcinogenic effects of the drug. The induction of thyroid tumors in rats by GF is apparently a consequence of the decrease of thyroxin levels and it is unlikely that such effects occur in GF-exposed humans. The appearance of hepatocellular carcinomas (HCC) in mice on GF-supplemented diet is preceded by various biochemical and morphological changes in the liver. Among these, hepatic porphyria is prominent, it may result from inhibition of ferrochelatase and (compensatory) induction of ALA synthetase. GF-induced accumulation of porphyrins in mouse liver is followed by cell damage and necrotic and inflammatory processes. Similar changes are known from certain human porphyrias which are also associated with an increased risk for HCC. However, the porphyrogenic effect of GF therapy in humans is moderate compared with that in the mouse model, although more detailed studies should be performed in order to clarify this relationship on a quantitative basis. A further important effect of GF-feeding in mice is the formation of Mallory bodies (MBs) in hepatocytes. These cytoskeletal abnormalities occur also in humans, although under different conditions; their appearance is associated with the induction of liver disease and HCC. Chronic liver damage associated with porphyria and MB formation, enhanced cell proliferation, liver enlargement, and enzyme induction all may contribute to the hepatocarcinogenic effect of GF in mice. In conclusion, further investigation is required for adequate assessment of health risks to humans under GF therapy.

Ubiquitin immunostaining and inclusion body myositis: study of 30 patients with inclusion body myositis

Distinction of inclusion body myositis (IBM) from other forms of inflammatory myopathy is significant from prognostic and therapeutic standpoints. This study retrospectively examines ubiquitin expression by paraffin immunohistochemistry in muscle biopsy material from 30 patients with IBM. Patients included 19 men and 11 women (ages 29 to 80 years; mean, 64 years). All biopsies were characterized by endomysial chronic inflammation, muscle fiber degeneration and regeneration, rimmed vacuoles, and angular atrophic esterase-positive muscle fibers. Ragged red fibers were identified in biopsies of five patients and a partial cytochrome C-oxidase deficiency by enzyme histochemistry in biopsies of 10 patients. Evidence of intranuclear or cytoplasmic tubulofilamentous structures confirming a diagnosis of IBM was observed in all 30 cases. Paracrystalline mitochondrial inclusions were noted in five patients. Discrete myocyte intranuclear ubiquitin-positive inclusions were noted in 14 patients (47%). Discrete intracytoplasmic ubiquitin-positive inclusions were noted in 24 (80%) patients. Positive staining of rimmed vacuoles by ubiquitin was observed in 25 (83%) patients. Diffuse staining of scattered muscle fibers was observed in 21 (70%) patients. In a control group including patients with polymyositis (n = 3), dermatomyositis (n = 3), necrotizing vasculitis (n = 1), and granulomatous myositis (n = 1), discrete intranuclear or cytoplasmic ubiquitin-positive inclusions were not observed. Rimmed vacuoles were not seen either by light microscopy or ubiquitin immunostaining in any of the eight cases. Occasional myofibers from all eight cases showed diffuse, positive muscle fiber staining. Although not present in all cases, evidence of ubiquitin-positive myocytic intranuclear or cytoplasmic inclusions or positive-staining rimmed vacuoles in the setting of an inflammatory myopathy may be suggestive of a diagnosis of inclusion body myositis. Use of ubiquitin immunohistochemistry may be useful in cases in which frozen tissue or tissue processed for electron microscopy is not available, and IBM is suspected. Light or electron microscopic evidence of mitochondrial abnormalities were noted in a significant subset of patients (13 of 30; 43%) of patients with IBM.