tetracycline and Neurodegenerative-Diseases

The identification of molecules that inhibit protein deposition or reverse fibril formation could open new strategies for therapeutic intervention in misfolding diseases. Numerous compounds have been shown to inhibit amyloid fibril formation in vitro. Among these compounds, tetracycline and the disaccharide trehalose have been reported to inhibit or reverse amyloid aggregation but their efficiency as potential drugs is controversial.. The results obtained using tetracycline and trehalose, reported in the last 15 years, are described and discussed.. The conclusions have important implications for the development of therapeutic agents for protein deposition diseases. If fibrillar proteins contribute to cell degeneration, then the disassembly of fibrils may reverse or slow down disease progression; however, if the action of therapeutic agents produces intermediates of fibrillation and/or products of fibril disaggregation, then their accumulation could be harmful.. Care should be taken to ensure that strategies aimed at inhibiting fibril formation do not cause a corresponding increase in the concentration of toxic oligomeric species.

Topics: Amyloid; Amyloidogenic Proteins; Humans; Molecular Targeted Therapy; Neurodegenerative Diseases; Protein Synthesis Inhibitors; Proteins; Proteostasis Deficiencies; Tetracycline; Trehalose

The possibility of regulating individual gene activities in the mouse brain via the tetracycline-controlled transcriptional activation systems has sparked the development of novel mouse models aimed at elucidating the molecular mechanisms of brain disorders such as Huntington's, prion and Parkinson's diseases. In the past year, novel experimental strategies and methodological advances have emerged, contributing to the resolution of some of the initial limitations of these regulatory systems.

Topics: Animals; Brain Chemistry; Gene Expression; Humans; Nerve Tissue Proteins; Neurodegenerative Diseases; Protein Synthesis Inhibitors; Tetracycline

Topics: Alzheimer Disease; Animals; Doxycycline; Escherichia coli; Genetic Vectors; Glycogen Synthase Kinase 3 beta; Hippocampus; Mice; Mice, Transgenic; Neurodegenerative Diseases; Neurogenesis; Neurons; Promoter Regions, Genetic; Repressor Proteins; Retroviridae; Tetracycline; Transcriptional Activation

Postoperative cognitive dysfunction (POCD) is reported to occur frequently after all types especially cardiac surgery in elderly patients. It can be short-term or long-term and some cases even develop into Alzheimer's disease (AD). Although multi-risk factors associated with POCD have been identified, the etiology and pathophysiological mechanisms of this surgical complication remain elusive. Therefore, developing strategies for preventing or treating POCD is still challenging. However, increasing evidence suggests that central and systemic inflammation triggered by surgery likely plays a fundamental role in POCD developing and progression. Minocycline, a tetracycline derivative with anti-inflammatory properties, has been shown to be effective in treating neuroinflammatory related conditions or neurodegenerative diseases such as AD, Parkinson's disease, Huntington's disease. Considering that inflammation may be a potential factor of POCD and minocycline is effective in improving cognitive dysfunction induced by inflammation, we hypothesize that minocycline may be useful to treat/prevent the POCD development after surgery in elderly patients.

Topics: Aged; Anti-Bacterial Agents; Anti-Inflammatory Agents; Brain Diseases; Cognition Disorders; Humans; Inflammation; Minocycline; Models, Theoretical; Neurodegenerative Diseases; Postoperative Complications; Sepsis; Tetracycline; Treatment Outcome

Vectors suitable for delivery of therapeutic genes to the CNS for chronic neurodegenerative diseases will require regulatable transgene expression. In this study, three self-regulating rAAV vectors encoding humanized green fluorescent protein (hGFP) were made using the tetracycline (tet)-off system. Elements were cloned in different orientations relative to each other and to the AAV internal terminal repeat (ITRs). The advantage of this vector system is that all infected cells will carry both the 'therapeutic' gene and the tet-regulator. To compare the efficiency of the vectors, 293T cells infected by each vector were grown in the presence or absence of the tet-analog doxycycline (dox). Cells were analyzed by flow cytometry for hGFP protein expression, and quantitative RT-PCR (QRT-PCR) for levels of hGFP mRNA and the tet-activator (tTA) mRNA. In the presence of dox, cells infected with one of the vectors, rAAVS3, showed less than 2% total fluorescent intensity and mRNA copy number than cells grown without dox. The other two vectors were significantly more leaky. Levels of tTA mRNA were not affected by dox. The S3 vector also displayed tight regulation in HeLa and HT1080 cells. To assess regulation in the brain, the S3 vector was injected into rat striatum and rats maintained on regular or dox-supplemented water. At 1 month after vector injection, numerous positive cells were observed in rats maintained on regular water whereas only rare positive cells with very low levels of fluorescence were observed in rats maintained on water containing dox. The QRT-PCR analysis showed that dox inhibited expression of hGFP mRNA in brain by greater than 99%. These results demonstrate that exceedingly tight regulation of transgene expression is possible using the tet-off system in the context of a self-regulating rAAV vector and that the specific orientation of two promoters relative to each other and to the ITRs is important. Regulatable vectors based on this design are ideal for therapeutic gene delivery to the CNS.

Topics: Animals; Cell Line; Central Nervous System; Dependovirus; Doxycycline; Flow Cytometry; Gene Expression; Gene Expression Regulation; Genetic Therapy; Genetic Vectors; Green Fluorescent Proteins; HeLa Cells; Humans; Luminescent Proteins; Neurodegenerative Diseases; Rats; Rats, Inbred F344; Recombinant Proteins; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger; Tetracycline; Transgenes

Transmissible spongiform encephalopathies are neurodegenerative diseases and are considered to be caused by malformed prion proteins accumulated into fibrillar structures that can then aggregate to form larger deposits or amyloid plaques. The identification of fibril-interfering compounds is of therapeutic and prophylactic interest. A robust and easy-to-perform, high-throughput, in vitro fluorescence assay was developed for the detection of such compounds. The assay was based on staining with the fluorescent probe thioflavin S in polystyrene microtiter plates to determine the amyloid state of synthetic peptides, representing a putative transmembrane domain of human and mouse prion protein. In determining optimal test conditions, it was found that drying peptides from phosphate buffer prior to staining resulted in good reproducibility with an interassay variation coefficient of 8%. Effects of thioflavin S concentration and staining time were established. At optimal thioflavin S concentration of 0.2mg/ml, the fluorescence signals of thioflavin S with five different prion protein-based fibrillogenic peptides, as well as peptide Abeta((1-42)), were found to show a peptide-dependent linear correlation within a peptide concentration range of 10-400 microM. The ability of the assay to identify compounds that interfere with fibril formation and/or dissociate preformed fibrils was demonstrated for tetracyclic compounds by preceding coincubation with human prion protein peptide huPrP106-126.

Topics: Amino Acid Sequence; Benzothiazoles; Drug Evaluation, Preclinical; Fluorescent Dyes; Gelatin; Humans; Models, Molecular; Molecular Sequence Data; Neurodegenerative Diseases; Neurofibrils; Peptide Fragments; Prions; Reproducibility of Results; Sensitivity and Specificity; Staining and Labeling; Tetracycline; Thiazoles; Time Factors

Genetic evidence indicates that several mutations in tau, including G272V, are linked to frontotemporal dementia with parkinsonism. We expressed this mutation in mouse brains by combining a prion protein promoter-driven expression system with an autoregulatory transactivator loop that resulted in high expression of human G272V tau in neurons and in oligodendrocytes. We show that G272V tau can form filaments in murine oligodendrocytes. Electron microscopy established that the filaments were either straight or had a twisted structure; these were 17-20 nm wide and had a periodicity of approximately 75 nm. Filament formation was associated with tau phosphorylation at distinct sites, including the AT8 epitope 202/205 in vivo. Immunogold electron microscopy of sarcosyl-extracted spinal cords from G272V transgenic mice using phosphorylation-dependent antibodies AT8 or AT100 identified several sparsely gold-labelled 6-nm filaments. In the spinal cord, fibrillary inclusions were also identified by thioflavin-S fluorescent microscopy in oligodendrocytes and motor neurons. These results establish that expression of the G272V mutation in mice causes oligodendroglial fibrillary lesions that are similar to those seen in human tauopathies.

Topics: Animals; Central Nervous System; Cytoskeleton; Disease Models, Animal; Immunohistochemistry; Mice; Mice, Transgenic; Microscopy, Electron; Mutation; Nerve Degeneration; Neurodegenerative Diseases; Neurofibrillary Tangles; Neurons; Oligodendroglia; Phosphorylation; Solubility; tau Proteins; Tetracycline; Trans-Activators