Granulovacuolar Degenerations Appear in Relation to Hippocampal Phosphorylated Tau Accumulation in Various Neurodegenerative Disorders

BACKGROUND: Granulovacuolar degeneration (GVD) is one of the pathological hallmarks of Alzheimer's disease (AD), and it is defined as electron-dense granules within double membrane-bound cytoplasmic vacuoles. Several lines of evidence have suggested that GVDs appear within hippocampal pyramidal neurons in AD when phosphorylated tau begins to aggregate into early-stage neurofibrillary tangles. The aim of this study is to investigate the association of GVDs with phosphorylated tau pathology to determine whether GVDs and phosphorylated tau coexist among different non-AD neurodegenerative disorders. METHODS: An autopsied series of 28 patients with a variety of neurodegenerative disorders and 9 control patients were evaluated. Standard histological stains along with immunohistochemistry using protein markers for GVD and confocal microscopy were utilized. RESULTS: The number of neurons with GVDs significantly increased with the level of phosphorylated tau accumulation in the hippocampal regions in non-AD neurodegenerative disorders. At the cellular level, diffuse staining for phosphorylated tau was detected in neurons with GVDs. CONCLUSIONS: Our data suggest that GVDs appear in relation to hippocampal phosphorylated tau accumulation in various neurodegenerative disorders, while the presence of phosphorylated tau in GVD-harbouring neurons in non-AD neurodegenerative disorders was indistinguishable from age-related accumulation of phosphorylated tau. Although GVDs in non-AD neurodegenerative disorders have not been studied thoroughly, our results suggest that they are not incidental findings, but rather they appear in relation to phosphorylated tau accumulation, further highlighting the role of GVD in the process of phosphorylated tau accumulation

Immunohistochemical Characterisation of Cell-Type Specific Expression of CK1δ in Various Tissues of Young Adult BALB/c Mice

BACKGROUND: Casein kinase 1 delta (CK1delta) phosphorylates many key proteins playing important roles in such biological processes as cell growth, differentiation, apoptosis, circadian rhythm and vesicle transport. Furthermore, deregulation of CK1delta has been linked to neurodegenerative diseases and cancer. In this study, the cell specific distribution of CK1delta in various tissues and organs of young adult BALB/c mice was analysed by immunohistochemistry. METHODOLOGY/PRINCIPAL FINDINGS: Immunohistochemical staining of CK1delta was performed using three different antibodies against CK1delta. A high expression of CK1delta was found in a variety of tissues and organ systems and in several cell types of endodermal, mesodermal and ectodermal origin. CONCLUSIONS: These results give an overview of the cell-type specific expression of CK1delta in different organs under normal conditions. Thus, they provide evidence for possible cell-type specific functions of CK1delta, where CK1delta can interact with and modulate the activity of key regulator proteins by site directed phosphorylation. Furthermore, they provide the basis for future analyses of CK1delta in these tissues

Dual modification of Alzheimer’s disease PHF-tau protein by lysine methylation and ubiquitylation: a mass spectrometry approach

In sporadic Alzheimer’s disease (AD), neurofibrillary lesion formation is preceded by extensive post-translational modification of the microtubule associated protein tau. To identify the modification signature associated with tau lesion formation at single amino acid resolution, immunopurified paired helical filaments were isolated from AD brain and subjected to nanoflow liquid chromatography–tandem mass spectrometry analysis. The resulting spectra identified monomethylation of lysine residues as a new tau modification. The methyl-lysine was distributed among seven residues located in the projection and microtubule binding repeat regions of tau protein, with one site, K254, being a substrate for a competing lysine modification, ubiquitylation. To characterize methyl lysine content in intact tissue, hippocampal sections prepared from post mortem late-stage AD cases were subjected to double-label confocal fluorescence microscopy using anti-tau and anti-methyl lysine antibodies. Anti-methyl lysine immunoreactivity colocalized with 78 ± 13% of neurofibrillary tangles in these specimens. Together these data provide the first evidence that tau in neurofibrillary lesions is post-translationally modified by lysine methylation

The ubiquitin proteasome system in neuropathology

The ubiquitin proteasome system (UPS) orchestrates the turnover of innumerable cellular proteins. In the process of ubiquitination the small protein ubiquitin is attached to a target protein by a peptide bond. The ubiquitinated target protein is subsequently shuttled to a protease complex known as the 26S proteasome and subjected to degradative proteolysis. The UPS facilitates the turnover of proteins in several settings. It targets oxidized, mutant or misfolded proteins for general proteolytic destruction, and allows for the tightly controlled and specific destruction of proteins involved in development and differentiation, cell cycle progression, circadian rhythms, apoptosis, and other biological processes. In neuropathology, alteration of the UPS, or mutations in UPS target proteins may result in signaling abnormalities leading to the initiation or progression of tumors such as astrocytomas, hemangioblastomas, craniopharyngiomas, pituitary adenomas, and medulloblastomas. Dysregulation of the UPS may also contribute to tumor progression by perturbation of DNA replication and mitotic control mechanisms, leading to genomic instability. In neurodegenerative diseases caused by the expression of mutant proteins, the cellular accumulation of these proteins may overload the UPS, indirectly contributing to the disease process, e.g., sporadic Parkinsonism and prion diseases. In other cases, mutation of UPS components may directly cause pathological accumulation of proteins, e.g., autosomal recessive Parkinsonism and spinocerebellar ataxias. Defects or dysfunction of the UPS may also underlie cognitive disorders such as Angelman syndrome, Rett syndrome and autism, and muscle and nerve diseases, e.g., inclusion body myopathy and giant axon neuropathy. This paper describes the basic biochemical mechanisms comprising the UPS and reviews both its theoretical and proven involvement in neuropathological diseases. The potential for the UPS as a target of pharmacological therapy is also discussed

Stages of granulovacuolar degeneration: their relation to Alzheimer's disease and chronic stress response

status: publishe

Inflammatory Cytokines in Jet Propulsion Fuel-8 Induced Irritant Contact Dermatitis in Male Fischer Rats

Contact dermatitis is one of the most common occupational diseases. Absenteeism of the affected workers and associated health care costs makes this disease an economically important issue. Irritant contact dermatitis (ICD) is a common contact dermatitis observed among workers. As each category of irritants triggers the inflammatory process by different method, studying the mechanism of ICD is difficult. Information on the mechanism of action of an irritant is indispensable for the development of effective prophylactic and therapeutic measures. In this study, we have investigated the early changes in rat skin induced by jet fuel-8 (JP-8). Although previous studies have described the cytokines involved in the latter phase of the inflammatory process induced by JP-8, there is no information on the molecular mechanisms that leads to the downstream events. Gallucci et al., (2004) and Chatterjee et al., (2006) has shown that JP-8 induces elevated levels of interleukin-1 alpha (IL-1 alpha) in skin and cultured keratinocytes, respectively. The preformed and stored proinflammatory cytokine, IL-1 alpha that has autocrine and paracrine functions, appear to trigger the cascade of events that leads to the JP-8-induced contact dermatitis. We hypothesize that JP-8 induces increased levels of IL-1 alpha at early post-exposure time points. To test our hypothesis, we applied JP-8 in an occlusive patch for 1 h on the rat skin and measured IL-1 at 0, 1, 2, 3, 4, and 8 h post exposure. Neutrophils infiltrate the skin during the late phase of the inflammatory process; therefore we studied the neutrophil infiltration during the selected time points and measured the levels of CXCL2, the cytokine associated with the infiltration of neutrophils. Preformed and stored IL-1 might play an important role in the JP-8 induced gene expression in skin. We hypothesized that that blocking of IL-1 receptor will inhibit the JP-8 induced gene expression pattern. To test our hypothesis, we delivered IL-1 receptor antagonist into the skin before JP-8 treatment. We found that At 3 h post exposure, IL-1 alpha was reduced in JP-8 exposed skin and the selected time points were too early in the inflammatory cascade to reveal infiltration of neutrophils, although there was a slight increase in the level of CXCL2 at 2 h post exposure. Because IL-1 beta has similar biological effects, we measured this cytokine from the same samples used for IL-1 alpha quantification. IL-1 beta did not significantly change throughout the study. The decrease in the level of IL-1 alpha implies that JP-8 induces the release of the preformed IL-1 alpha. IL-1 receptor antagonist did not cause significant changes in the gene expression pattern. We conclude that the release of the preformed IL-1 alpha by JP-8 is one of the important events at the early time points of the JP-8-induced cascade of events

Casein Kinase 1 Alpha Associates With the Tau-Bearing Lesions of Inclusion Body Myositis

Inclusion body myositis and Alzheimer\u27s disease are age-related disorders characterized in part by the appearance of intracellular lesions composed of filamentous aggregates of the microtubule-associated protein tau. Abnormal tau phosphorylation accompanies tau aggregation and may be an upstream pathological event in both diseases. Enzymes implicated in tau hyperphosphorylation in Alzheimer\u27s disease include members of the casein kinase 1 family of phosphotransferases, a group of structurally related protein kinases that frequently function in tandem with the ubiquitin modification system. To determine whether casein kinase 1 isoforms associate with degenerating muscle fibers of inclusion body myositis, muscle biopsy sections isolated from sporadic disease cases were subjected to double-label fluorescence immunohistochemistry using selective anti-casein kinase 1 and anti-phospho-tau antibodies. Results showed that the alpha isoform of casein kinase 1, but not the delta or epsilon isoforms, stained degenerating muscle fibers in all eight inclusion body myositis cases examined. Staining was almost exclusively localized to phospho-tau-bearing inclusions. These findings, which extend the molecular similarities between inclusion body myositis muscle and Alzheimer\u27s disease brain, implicate casein kinase 1 alpha as one of the phosphotransferases potentially involved in tau hyperphosphorylation