Human fetal tau protein isoform: Possibilities for Alzheimer's disease treatment

Croatian Institute for Brain Research, University of Zagreb School of Medicine, Šalata 12, 10000 Zagreb, Croatia.
The international journal of biochemistry & cell biology (Impact Factor: 4.05). 05/2012; 44(8):1290-4. DOI: 10.1016/j.biocel.2012.05.001
Source: PubMed


While early 1990s reports showed the phosphorylation pattern of fetal tau protein to be similar to that of tau in paired helical filaments (PHF) in Alzheimer's disease (AD), neither the molecular mechanisms of the transient developmental hyperphosphorylation of tau nor reactivation of the fetal plasticity due to re-expression of fetal protein kinases in the aging and AD human brain have been sufficiently investigated. Here, we summarize the current knowledge on fetal tau, adding new data on the specific patterns of tau protein and mRNA expression in the developing human brain as well as on change in tau phosphorylation in the perforant pathway after entorhinal cortex lesion in mice. As fetal tau isoform does not form PHF even in a highly phosphorylated state, understanding its expression and post-translational modifications represents an important avenue for future research towards the development of AD treatment and prevention.

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    • "Nevertheless, p-tau has more than 80% specificity in differentiating AD from other primary causes of dementia (61). Additionally, normal p-tau levels were found in pathological states like VaD, FTD, LBD, during depression, and after stroke, while fetal tau isoform is normally hyperphosphorylated during development (49,52,62,63). However, a moderate increase in p-tau was observed in CJD (52), as well as a decrease in both t-tau and p-tau in Parkinson disease (64). "
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    ABSTRACT: Alzheimer disease (AD) is a complex neurodegenerative disorder, whose prevalence will dramatically rise by 2050. Despite numerous clinical trials investigating this disease, there is still no effective treatment. Many trials showed negative or inconclusive results, possibly because they recruited only patients with severe disease, who had not undergone disease-modifying therapies in preclinical stages of AD before severe degeneration occurred. Detection of AD in asymptomatic at risk individuals (and a few presymptomatic individuals who carry an autosomal dominant monogenic AD mutation) remains impractical in many of clinical situations and is possible only with reliable biomarkers. In addition to early diagnosis of AD, biomarkers should serve for monitoring disease progression and response to therapy. To date, the most promising biomarkers are cerebrospinal fluid (CSF) and neuroimaging biomarkers. Core CSF biomarkers (amyloid β1-42, total tau, and phosphorylated tau) showed a high diagnostic accuracy but were still unreliable for preclinical detection of AD. Hence, there is an urgent need for detection and validation of novel CSF biomarkers that would enable early diagnosis of AD in asymptomatic individuals. This article reviews recent research advances on biomarkers for AD, focusing mainly on the CSF biomarkers. In addition to core CSF biomarkers, the potential usefulness of novel CSF biomarkers is discussed.
    Full-text · Article · Aug 2014 · Croatian Medical Journal
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    ABSTRACT: Alzheimer’s disease (AD) is a progressive neurodegenerative disorder characterized by the extracellular deposits of β amyloid peptides (Aβ) in senile plaques, and intracellular aggregates of hyperphosphorylated tau in neurofibrillary tangles (NFT). Although accumulation of Aβ has been long considered a leading hypothesis in the disease pathology, it is increasingly evident that the role hyperphosphorylation of tau in destabilization of microtubule assembly and disturbance of axonal transport is equally detrimental in the neurodegenerative process. The main kinase involved in phosphorylation of tau is glycogen-synthase kinase 3-beta (GSK-3β). Intracellular accumulation of Aβ also likely induces increase in hyperphosphorylated tau by a mechanism dependent on GSK-3β. In addition, Aβ affects production of ceramides, the major sphingolipids in mammalian cells, by acting on sphingomyelinases, enzymes responsible for the catabolic formation of ceramides from the sphingomyelin. Generated ceramides in turn increase production of Aβ by acting on β-secretase, a key enzyme in the proteolytic processing of the amyloid precursor protein (APP), altogether leading to a ceramide-Aβ-hyperphosphorylated tau cascade that ends in neuronal death. Modulators and inhibitors acting on members of this devastating cascade are considered as potential targets for AD therapy. There is still no adequate treatment for AD patients. Novel therapeutic strategies increasingly consider the combination of multiple targets and interactions among the key members of implicated molecular pathways. This review summarizes recent findings and therapeutic perspectives in the pathology and treatment of AD, with the emphasis on the interplay between hyperphosphorylated tau, amyloid β, and sphingolipid mediators.
    Full-text · Article · Dec 2013
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    ABSTRACT: AimsRecent evidence supports the activation of mechanisms underlying cellular ageing and neurodegeneration in developmental lesions associated with epilepsy. The present study examined the ongoing cell injury and vulnerability to neuronal degeneration in glioneuronal tumours (GNT).Methods We evaluated a series of GNT (n= 31 gangliogliomas, GG and n= 30 dysembryoplastic neuroepithelial tumours, DNT). Sections were processed for immunohistochemistry using markers for the evaluation of caspase-3 and neurodegeneration-related proteins/pathways and their expression was correlated with the tumour features and the clinical history of epilepsy.ResultsBoth GG and DNT specimens contained caspase-3-positive cells. In GG, expression of activated caspase-3 was negatively correlated the with the BRAF V600E mutation status. We also observed an abnormal expression of death receptor-6 and β amyloid precursor protein (APP). Moreover, dysplastic neurones expressed p62, phosphorylated (p)TDP43 and pTau. Double labelling experiments showed co-localisation of phosphorylated S6 (marker of mammalian target of rapamycin, mTOR, pathway activation) with pTau and p62. In GG, neuronal p62 expression was positively correlated with pS6. The immunoreactivity score (IRS) of caspase-3, APP, DR6, p62 and pTDP43 were found to be significantly higher in GG than in DNT. Expression of APP, DR6, pTau (in GG and DNT) and caspase-3 (in GG) positively correlated with duration of epilepsy. In GG, the expression of neuronal caspase-3, DR6 and glial p62 was associated with a worse postoperative seizure outcome.Conclusions Our observations in GNT provide evidence of premature activation of mechanisms of neurodegeneration which are associated with the clinical course of epilepsy in patient with GG.
    No preview · Article · Apr 2014 · Neuropathology and Applied Neurobiology
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