24 Tau proteins arc widely expressed in the central nervous system (CNS), predominantly in axons, and to a much lesser extent in glial cells.25 During neurodegenerative diseases, tau is redistributed to the somatodendritic compartments. In the human brain, six isoforms of tau ranging from 352 to 441 amino acids
are produced from a single gene mapping to 17q21 by alternative mRNA splicing.25 In the AD brain, Inhibitors,research,lifescience,medical PHF tau is abnormally phosphorylatcd.26 Consequently, the kinases and phosphatases regulating tau click here phosphorylation are a focus of therapeutic research. A portion of FTD syndromes is characterized by prominent filamentous tau inclusions and neurodegeneration in the absence of β-amyloid deposition. This tau form of FTD was therefore grouped together with other neurodegenerative diseases where tau pathology was predominant and termed “tauopathies”: sporadic corticobasal degeneration, progressive supranuclear palsy, Pick’s disease,
as well as hereditary FTD and Parkinsonism linked to Inhibitors,research,lifescience,medical chromosome 17 (FTD -17).25 Clinical manifestations of the tauopathies are not restricted to the brain; they may include other organ systems, eg, in Hallervorden-Spatz disease, myotonic dystrophy, or Niemann-Pick disease type C. Tau proteins vary among the different tauopathies in isoform and phosphorylation state. Since several tau mutations were shown to be causative for several tauopathies including FTD, tau abnormalities Inhibitors,research,lifescience,medical that may be mechanistically involved in the pathogenesis of ncurodegeneration were investigated. It was hypothesized that different tau mutations are pathogenic because they impair tau function, promote tau fibrillization, or perturb tau gene splicing, thereby leading to formation of biochemically and structurally distinct aggregates of tau.25 Collectively, tauopathies, Inhibitors,research,lifescience,medical including a portion of FTD, are associated with deposition of aggregated, abnormally phosphorylatcd tau proteins which normally stabilize microtubule function in the cell. Dementia with Lewy bodies DLB accounts for about 20% of the dementias in
the elderly27 This disorder has clinical and pathological features Inhibitors,research,lifescience,medical in common with both AD and Parkinson’s disease (PD).19,27 Dementia is often associated with Parkinsonism, visual Thiamine-diphosphate kinase hallucinations, orthostatic hypotension, and, typically, fluctuations in cognitive performance and levels of consciousness.19,27 Lewy bodies contain filamentous aggregates and α-synuclcin as major constituents28 and deposit in paralimbic and cortical brain areas along with neuritic changes.29,30 Cooccurrence of β-amyloid plaques and vascular disease is frequent, whereas the presence of NFTs is rare.31 In contrast to FTD and in line with AD, there is a pronounced deficit in cholinergic neurotransmission, which makes this disease a possible indication for treatment with acetylcholinesterase inhibitors.27 α-Synuclcin is abundantly expressed in presynaptic terminals and probably regulates synaptic neurotransmission.