RSSThe tau-like protein in silkworm (Bombyx mori) induces microtubule bundle formation.
Source
The Key Laboratory of Cell Proliferation and Differentiation of Ministry of Education; The State Key Laboratory of Bio-membrane and Membrane Bio-engineering, College of Life Sciences, Peking University, Beijing 100871, China.
Abstract
Tau proteins are major microtubule-associated proteins (MAPs), which promote polymerization of tubulin and determine spacings between microtubules in axons of both the central and peripheral nervous systems (CNS and PNS). Here, we cloned and identified a tau-like protein BmTau from silkworm, Bombyx mori (GenBank accession number FJ904935). The coding sequence of BmTau is 723 bases long and encodes an approximate 30kDa protein. In the C-terminus of BmTau are contained four predicted microtubule-binding domains, which share strong sequence homology to its ortholog in Drosophila melanoganster. Relative real-time PCR analysis showed ubiquitous expression of BmTau in both neurons and non-neural cells, with its mRNA abundantly expressing in brain but significantly less detected in trachea, fat body, and silkgland. Furthermore, immunocytochemical studies in BmN cells transfected with EGFP-BmTau indicated that BmTau functioned as microtubule bundling protein as its orthologues.
- PMID:
- 22201930
- [PubMed - in process]
WW domain-containing oxidoreductase promotes neuronal differentiation via negative regulation of glycogen synthase kinase 3β
Source
Institute of Clinical Medicine, National Cheng Kung University Medical College, Tainan, Taiwan.
Abstract
WW domain-containing oxidoreductase (WWOX), a putative tumour suppressor, is suggested to be involved in the hyperphosphorylation of Alzheimer's Tau. Tau is a microtubule-associated protein that has an important role inmicrotubule assembly and stability. Glycogen synthase kinase 3β (GSK3β) has a vital role in Tau hyperphosphorylation at its microtubule-binding domains. Hyperphosphorylated Tau has a low affinity for microtubules, thus disruptingmicrotubule stability. Bioinformatics analysis indicated that WWOX contains two potential GSK3β-binding FXXXLI/VXRLE motifs. Immunofluorescence, immunoprecipitation and molecular modelling showed that WWOX interacts physically with GSK3β. We demonstrated biochemically that WWOX can bind directly to GSK3β through its short-chain alcohol dehydrogenase/reductase domain. Moreover, the overexpression of WWOX inhibited GSK3β-stimulated S396 and S404 phosphorylation within the microtubule domains of Tau, indicating that WWOX is involved in regulating GSK3β activity in cells. WWOX repressed GSK3β activity, restored the microtubule assembly activity of Tau and promoted neurite outgrowth in SH-SY5Y cells. Conversely, RNAi-mediated knockdown of WWOX in retinoic acid (RA)-differentiated SH-SY5Y cells inhibited neurite outgrowth. These results suggest that WWOX is likely to be involved in regulating GSK3β activity, reducing the level of phosphorylated Tau, and subsequently promoting neurite outgrowth during neuron differentiation. In summary, our data reveal a novel mechanism by which WWOX promotes neuronal differentiation in response to RA.Cell Death and Differentiation advance online publication, 23 December 2011; doi:10.1038/cdd.2011.188.
Effect of chronic administration of estradiol, progesterone, and tibolone on the expression and phosphorylation of glycogen synthase kinase-3β and themicrotubule-associated protein tau in the hippocampus and cerebellum of female rat.
Source
Unidad de Investigación Médica en Farmacología, Hospital de Especialidades, Centro Médico Nacional Siglo XXI, Instituto Mexicano del Seguro Social, México D.F., México.
Abstract
Gonadal hormones regulate expression and activation of protein tau. Tibolone is a drug used as first- choice comprehensive treatment for the relief of menopausal symptoms, because it and its various metabolites have estrogenic properties and progestogenic/androgenic effects; however, the effect on the activation of tau protein and its signaling cascade in the brain is unknown. We studied the effect of chronic administration of estradiol (E2), progesterone (P4), and tibolone (TIB) on the expression and phosphorylation of microtubule-associated protein tau and glycogen synthase kinase-3β (GSK3β) in the hippocampus and cerebellum of ovariectomized rats. Ovariectomized adult female rats were implanted with pellets of vehicle, E2, or P4 or were treated with TIB by oral administration for 60 days. The animals were sacrificed, and tissue proteins were analyzed by Western blot. We observed that, in the hippocampus, administration of E2, P4, or TIB significantly decreased the protein content of hyperphosphorylated tau and increased the taudephosphorylated form, whereas only treatment with TIB increased the content of the phosphorylated form of GSK3β. In the cerebellum, E2 and TIB treatments resulted in a significant decrease in the expression of hyperphosphorylated tau, whereas E2 and TIB increased phosphorylated GSK3β; P4 had no effect. These results indicate that chronic administration of gonadal hormones and tibolone modulates tau and GSK3β phosphorylation in hippocampus and cerebellum of the rat and may exert a neuroprotective effect in these tissues. © 2011 Wiley Periodicals, Inc.
Copyright © 2011 Wiley Periodicals, Inc.
Frontotemporal lobar degeneration related proteins induce only subtle memory-related deficits when bilaterally overexpressed in the dorsal hippocampus.
Source
Department of Pharmacology, Toxicology, and Neuroscience, Louisiana State University Health Sciences Center, 1501 Kings Hwy, Shreveport, LA 71130, USA.
Abstract
Frontotemporal lobar degeneration (FTLD) is a neurodegenerative disease that involves cognitive decline and dementia. To model the hippocampal neurodegeneration and memory-related behavioral impairment that occurs in FTLD and othertau and TDP-43 proteinopathy diseases, we used an adeno-associated virus serotype 9 (AAV9) vector to induce bilateral expression of either microtubule-associated protein tau or transactive response DNA binding protein 43kDa (TDP-43) in adult rat dorsal hippocampus. Human wild-type forms of tau or TDP-43 were expressed. The vectors/doses were designed for moderate expression levels within neurons. Rats were evaluated for acquisition and retention in the Morris water task over 12weeks after gene transfer. Neither vector altered acquisition performance compared to controls. In measurements of retention, there was impairment in the TDP-43 group. Histological examination revealed specific loss of dentate gyrus granule cells and concomitant gliosis proximal to the injection site in the TDP-43 group, with shrinkage of the dorsal hippocampus. Despite specific tau pathology, the tau gene transfer surprisingly did not cause obvious neuronal loss or behavioral impairment. The data demonstrate that TDP-43 produced mild behavioral impairment and hippocampal neurodegeneration in rats, whereas tau did not. The models could be of value for studying mechanisms of FTLD and other diseases with tau and TDP-43 pathology in the hippocampus including Alzheimer's disease, with relevance to early stage mild impairment.
Copyright © 2011. Published by Elsevier Inc.
Tau-Targeted Immunization Impedes Progression of Neurofibrillary Histopathology in Aged P301L Tau Transgenic Mice.
Source
Laboratory for Translational Neurodegeneration, Brain and Mind Research Institute, The University of Sydney, Camperdown, New South Wales, Australia.
Abstract
In Alzheimer's disease (AD) brains, the microtubule-associated protein tau and amyloid-β (Aβ) deposit as intracellular neurofibrillary tangles (NFTs) and extracellular plaques, respectively. Tau deposits are furthermore found in a significant number of frontotemporal dementia cases. These diseases are characterized by progressive neurodegeneration, the loss of intellectual capabilities and behavioral changes. Unfortunately, the currently available therapies are limited to symptomatic relief. While active immunization against Aβ has shown efficacy in both various AD mouse models and patients with AD, immunization against pathogenic tau has only recently been shown to prevent pathology in young tautransgenic mice. However, if translated to humans, diagnosis and treatment would be routinely done when symptoms are overt, meaning that the histopathological changes have already progressed. Therefore, we used active immunization to target pathogenic tau in 4, 8, and 18 months-old P301L tau transgenic pR5 mice that have an onset of NFT pathology at 6 months of age. In all age groups, NFT pathology was significantly reduced in treated compared to control pR5 mice. Similarly, phosphorylation of tau at pathological sites was reduced. In addition, increased astrocytosis was found in the oldest treated group. Taken together, our data suggests that tau-targeted immunization slows the progression of NFT pathology in mice, with practical implications for human patients.
Hyperphosphorylated tau in young and middle-aged subjects.
Source
Department of Immunology, Genetics and Pathology, Rudbeck Laboratory, Uppsala University/Uppsala University Hospital, Dag Hammarskjölds väg 20, 751 85, Uppsala, Sweden.
Abstract
The brain tissue obtained from ninety-five cognitively unimpaired subjects, with ages ranging from 22 to 50 years upon death, were immunohistochemically assessed for neurodegenerative changes, i.e., hyperphosphorylated tau (HPτ) and β-amyloid (Aβ) pathology in predilection neuroanatomical areas. HPτ pathology was observed in the transentorhinal cortex and/or the locus coeruleus (LC) in 33% of the subjects, without any obvious risk factors known to alter themicrotubule-associated protein. HPτ pathology was noted in the LC in 25 out of 83 subjects (30%), lacking concomitant cortical Aβ or transentorhinal HPτ pathology. This observation was present even when assessing only one routine section of 7 μm thickness. The recent suggestion of prion-like propagation of neurodegeneration and the finding of neurodegeneration being quite common in middle-aged persons is alarming. It is noteworthy, however, that a substantial number of neurologically unimpaired subjects even at a very old age display only sparse to modest extent of neurodegenerative pathology. Thus, only a subset of subjects with neurodegenerative changes early in life seem to progress to a symptomatic disease with ageing. This observation brings forth the notion that other, yet unknown modifying factors influence the progression of degeneration that leads to a symptomatic disorder. The known association between alterations in the LC and mood disorders, and the finding of the LC being frequently affected with HPτ pathology suggest that clinicopathological studies on young subjects both with or without mood disorders are warranted.
Linking Amyloid-β and Tau: Amyloid-β Induced Synaptic Dysfunction via Local Wreckage of the Neuronal Cytoskeleton.
Source
Max Planck Unit for Structural Molecular Biology, Hamburg, Germany.
Abstract
Background: In Alzheimer's disease (AD), amyloid-β (Aβ) is the major component of extracellular plaques, whereas themicrotubule-associated protein tau forms the main component of intracellular tangles. In contrast to frontotemporal dementias and other neurodegenerative diseases, both proteins form pathological aggregates and are considered key players for the development of AD. However, the connection between Aβ and tau and the functional loss of neurons and synapses, which ultimately lead to cognitive impairments, is still not well understood. Objectives: Making use of primary neurons exposed to Aβ oligomers, we sought to determine how tau mediates the Aβ-induced neuronal dysfunction. Additionally, we asked how the microtubule cytoskeleton is involved in the combined Aβ and tau toxicity. Methods: We exposed mature primary rat neurons with developed synapses to Aβ oligomers and used immunofluorescence and electron microscopy to investigate tau, actin, neurofilament and microtuble cytoskeleton changes. Results: Aβ oligomers preferentially associate with synapses, notably dendritic spines, throughout the neuronal cell culture. As a consequence, endogenous tau gets missorted from the axonal into the somatodendritic compartment in a subset of cells. These missorted cells also display missorting of neurofilaments, and a dramatic loss of microtubules, which can be prevented by the microtubule stabilizer taxol. Conclusions: Aβ causes tau missorting, loss of neuronal cell polarity and loss of dendritic microtubules. This in turn leads to impaired organelle/mitochondria transport, whereby synapses cannot be maintained properly and eventually decay. The data support the view that the microtubule cytoskeleton is a valid therapeutic target in AD.
Copyright © 2011 S. Karger AG, Basel.
A critical role for the PAR-1/MARK-tau axis in mediating the toxic effects of Aβ on synapses and dendritic spines.
Source
Department of Pathology.
Abstract
Alzheimer's disease (AD) is the most common neurodegenerative disease and the leading cause of dementia in the elderly. Accumulating evidence supports soluble amyloid-β (Aβ) oligomers as the leading candidate for the causative agent in AD and synapses as the primary site of Aβ oligomer action. However, the molecular and cellular mechanisms by which Aβ oligomers cause synaptic dysfunction and cognitive impairments remain poorly understood. Using primary cultures of rat hippocampal neurons as a model system, we show that the partitioning defective-1 (PAR-1)/microtubuleaffinity-regulating kinase (MARK) family kinases act as critical mediators of Aβ toxicity on synapses and dendritic spines. Overexpression of MARK4 led to tau hyperphosphorylation, reduced expression of synaptic markers, and loss of dendritic spines and synapses, phenotypes also observed after Aβ treatment. Importantly, expression of a non-phosphorylatable form of tau with the PAR-1/MARK site mutated blocked the synaptic toxicity induced by MARK4 overexpression or Aβ treatment. To probe the involvement of endogenous MARK kinases in mediating the synaptic toxicity of Aβ, we employed a peptide inhibitor capable of effectively and specifically inhibiting the activities of all PAR-1/MARK family members. This inhibitor abrogated the toxic effects of Aβ oligomers on dendritic spines and synapses as assayed at the morphological and electrophysiological levels. Our results reveal a critical role for PAR-1/MARK kinases in AD pathogenesis and suggest PAR-1/MARK inhibitors as potential therapeutics for AD and possibly other tauopathies where aberrant tau hyperphosphorylation is involved.
Enriched odor exposure decrease tau phosphorylation in the rat hippocampus and cortex.
Source
Department of Pathophysiology, Key Laboratory of Neurological Diseases of Education Committee of China, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, PR China.
Abstract
Abnormally hyperphosphorylated microtubule-associated protein tau is the main component of the neurofibrillary tangles (NFT), a hallmark pathological feature of Alzheimer's disease (AD). A lot of studies suggested that there is highly neurobiological correlation between olfactory dysfunction and AD-like pathology, but the effect of the odor stimulation ontau phosphorylation remains unknown. Here, we examined the effect of short-term and long-term enriched odor exposure on the alterations of tau phosphorylation at multiple sites in the rat brains. We found that short-term odor enrichment did not affect the phosphorylation of tau, while long-term odor enrichment dramatically reduce the phosphorylation level oftau at Ser198/199/202, Thr231, Ser396, and Ser404 sites both in the hippocampus and cortex. These data suggest that long-term odor exposure prevent tau phosphorylation and may be a new therapeutic strategy of AD.
Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.
Dietary intake of cottonseed toxins is hypothesized to be a partial cause of Alzheimer's disorder.
Source
Wisconsin Institute of Nutrition, 6789 N. Green Bay Ave., Milwaukee, WI 53209, United States.
Abstract
The cause of Alzheimer's disorder is not known. The most influential known risk factor is increasing age. The risk factor of increasing age is consistent with exposure to environmental toxins throughout life as a cause of Alzheimer's. In addition, microbleeding, changes in membrane permeability and increased cholesterol are all factors important in Alzheimer's. Cottonseed contains toxins and is fed to animals, fish and poultry. Cottonseed toxins remain in the animals, fish and poultry and are present in the human diet at seemingly low levels. The average person is ingesting cottonseed toxins throughout life. Cottonseed toxins cause bleeding, changes in membrane permeability and increased cholesterol. In addition, the cottonseed toxin gossypol is known to reach the brain and bind randomly to important cellular structures. Gossypol also binds to microtubules and interferes with microtubule assembly, which may inhibit binding of tau to microtubules and lead to formation of neurofibrillary tangles. Cottonseed toxins are also known to accumulate in the body. In a preliminary study of female rats fed low level cottonseed for their lifetimes, apparent neurofibrillary tangles and phosphorylated tau were found. The intake of cottonseed toxins throughout life should be evaluated further as a possible cause of Alzheimer's.
Copyright © 2011 Elsevier Ltd. All rights reserved.
Prevalence of frontotemporal lobar degeneration in an isolated population: the Vallecamonica study.
Source
Department of Neurology, University of Brescia, Brescia, Italy.
Abstract
The study of neurodegenerative diseases, such as frontotemporal lobar degeneration (FTLD), in isolated populations represents a privileged point of view for identifying new causative genes and pathogenetic mechanisms. Vallecamonica is a valley located in the Brescia province (Northern Italy), which experienced isolation until the end of World War II. The aims of the present work were (1) to estimate the prevalence of FTLD in Vallecamonica, (2) to determine the monogenic FTLD forms, and (3) to identify FTLD cases with no evidence of known pathogenetic mutations and the related clinical features. Patients meeting current clinical criteria for FTLD were considered. Mutation analysis for microtubuleassociated protein tau (MAPT) and progranulin (PGRN) genes was performed, as well as serum PGRN dosage. On the census day, 42 FTLD patients were alive, resulting in an overall disease prevalence of 35 per 100 inhabitants. Thirty-one out of 42 patients underwent sequencing analysis. Five patients carried PGRN Thr272fs mutation and one patient MAPT P301L mutation. There were no differences in term of age at onset and gender between this group and mutation carriers, but the latter had greater family history for dementia (100%, P = 0.01). In Vallecamonica, we detected a higher prevalence of FTLD compared with that already reported in other populations. A founder effect or a genetic drift might be considered for an allelic enrichment. Ongoing study aims to identify the presence of a new genetic form in those FTLD patients without known pathogenetic mutations in this isolated population.
SNCA and MAPT genes: Independent and joint effects in Parkinson disease in the Italian population.
Source
Dipartimento di Biologia e Genetica per le Scienze Mediche, Università degli Studi di Milano, Milan, Italy; Medical Genetics Laboratory, Foundation IRCCS Cà Granda Ospedale Maggiore Policlinico, Milan, Italy.
Abstract
BACKGROUND:
Significant efforts have been focused on investigating the contribution of common variants to Parkinson disease (PD) risk. Several independent GWAS and metanalysis studies have shown a genome-wide significant association of single nucleotide polymorphisms (SNPs) in the α-synuclein (SNCA) and microtubule-associated proteintau (MAPT) regions. Here we investigated the role of SNCA and MAPT as PD susceptibility genes in a large Italian population of 904 patients and 891 controls. An evaluation of gene-gene and gene-environment interactions in association with PD was also attempted.
METHODS:
The SNCA Rep1 microsatellite was genotyped by a fluorescent PCR assay, whereas the SNPlex genotyping system was used to genotype 12 additional markers across the SNCA gene, and 2 SNPs tagging the risk MAPT H1 haplotype.
RESULTS:
Single-marker analysis demonstrated nominal evidence of association for: i) the 261-bp-long allele of Rep1; ii) 7 SNPs in the SNCA region (top SNP: rs356186, P = 3.08 × 10(-04), intron 4); iii) both SNPs identifying the MAPT H1 haplotype (P = 4.63 × 10(-04) and P = 4.23 × 10(-04) for rs1800547 and rs9468, respectively). Moreover, we found a highly significant protective haplotype spanning ∼83 kb from intron 4 to the 3' end of SNCA (P = 1.29 × 10(-05)).
CONCLUSIONS:
Our findings strongly confirm SNCA and MAPT as major PD susceptibility genes for idiopathic PD in the Italian population. Interaction analyses did not evidence either epistatic effects between the two loci or gene-environment interactions.
Copyright © 2011 Elsevier Ltd. All rights reserved.
Targeting post-translational modifications on tau as a therapeutic strategy for Alzheimer's disease.
Source
Department of Neurosymptomatics, Merck Research Laboratories, West Point, PA 19486, USA. jacob_marcus@merck.com
Abstract
Alzheimer's disease (AD) is a neurodegenerative disorder that causes early memory impairment, followed by profound progressive cognitive decline, and eventually death. Neurofibrillary tangles (NFTs) are one of the histopathological hallmarks of AD. NFTs are deposits of insoluble aggregates of the microtubule-binding protein tau, left behind following neuronal loss. Intracellular aggregates of tau, either in soluble or insoluble forms, are thought to disrupt cellular machinery and synaptic function and ultimately lead to neuronal death. As the ultimate pathological endpoint in AD is neuronal loss, there is significant interest in understanding the causes of tau aggregation and deposition in the brain as a potential therapeutic avenue for AD. Post-translational modifications on tau are thought to be an important regulatory mechanism that may contribute to the propensity of tau to aggregate and form NFTs. In addition to phosphorylation, numerous other post-translational modifications have been observed on tau protein. The mechanisms that cause aggregation of tau are unknown, but it is likely that post-translational modifications other than phosphorylation also regulate this process. This review will discuss several post-translational modifications of tau and their roles in modulation of tau function and aggregation in AD.
Insight into Potential Cu(II)-Binding Motifs in the Four Pseudorepeats of TauProtein.
Source
Department of Chemistry, University of Pittsburgh , 219 Parkman Avenue, Pittsburgh, Pennsylvania 15260, United States.
Abstract
Tau protein and Cu(II) are believed to be associated with the pathogenesis of Alzheimer's disease. However, little is known about atomic-level interactions between tau protein and Cu(II). Herein, we suggest, on the basis of electron spin resonance (ESR) data, that the four pseudorepeats of tau protein in the microtubule-binding region play an important role in Cu(II) binding. We use a number of tau protein fragments in order to examine Cu(II)-binding site(s) and binding affinities. Continuous-wave (CW) ESR experiments on the four highly conserved octadecapeptides, each of which is a segment of one of the four pseudorepeats, reveal that the equimolar Cu(II) complexes of the four octadecapeptides are similar to one another in terms of the coordination environment and binding affinity. The spectra obtained with pulsed ESR techniques such as electron spin-echo envelope modulation and hyperfine sublevel correlation provide direct evidence that a histidine residue and a backbone amide group coordinate to Cu(II) in each Cu(II)-octadecapeptide complex. The results of CW and pulsed ESR experiments on some chemically modified peptides indicate that the cysteine residues in the second and third pseudorepeats are unlikely to be involved in Cu(II) binding. On the other hand, similar experiments on tau fragments of the second pseudorepeat with different lengths lead to the conclusion that the affinity for Cu(II) decreases as the octadecapeptide is either truncated or elongated. The high Cu(II)-binding affinity of the octadecapeptide is presumably due to the N-terminal amino group stabilizing the Cu(II)-octadecapeptide complex. Finally, the ESR data for a longer tau fragment that contains two octadecapeptides suggest that the Cu(II) binding site(s) of even longer fragments of tau protein is similar to that of a single octadecapeptide.
Cooperative folding of tau peptide by coordination of group IIB metal cations during heparin-induced aggregation.
Source
Department of Chemistry, Tongji University, 1239 Siping Road, Shanghai, 200092, China.
Abstract
The group IIB elements, especially Cd(II) and Hg(II), are increasingly considered as potential environmental neurotoxins. This study demonstrates that the Alzheimer's tau fragment R2, corresponding to the second repeat of the microtubule-binding domain, can bind to Zn(II), Cd(II) and Hg(II). Isothermal titration calorimetry experiments suggest that the most likely coordination site is the thiol group of Cys291, and this is further confirmed by a control experiment using a C291A mutant peptide. Circular dichroism spectrum reveals that the coordination of group IIB cations, especially Hg(II), can induce pronounced conformational conversions in natively unfolded R2, from random coil to other ordered structures. ThS fluorescence assays and electron microscopy indicate that the group IIB cations promote heparin-induced aggregation of R2, giving relatively small R2 filaments. The efficiency in promoting aggregation, as well as inducing conformational conversion, varies strongly with the cation's polarizability. Based on these results, a model is proposed in which the cooperative folding of R2 through cross-bridging of group IIB cations is suggested to be a key factor in promoting aggregation, in addition to the effective neutralization of coulombic charge-charge repulsion by heparin, the poly-anion inducer. Our results provide clues to understanding the potential pathogenic role of group IIB metals in the development of neurofibrillary tangles, a typical hallmark of Alzheimer's disease.
Structural characterization by nuclear magnetic resonance of the impact of phosphorylation in the proline-rich region of the disordered Tau protein.
Source
CNRS-UMR 8576 UGSF-IFR 147, Université des Sciences et Technologies de Lille 1, 59655 Villeneuve d'Ascq Cedex, France.
Abstract
Phosphorylation of the neuronal Tau protein is implicated in both the regulation of its physiological function ofmicrotubule stabilization and its pathological propensity to aggregate into the fibers that characterize Alzheimer's diseased neurons. However, how specific phosphorylation events influence both aspects of Tau biology remains largely unknown. In this study, we address the structural impact of phosphorylation of the Tau protein by Nuclear Magnetic Resonance (NMR) spectroscopy on a functional fragment of Tau (Tau[Ser208-Ser324] = TauF4). TauF4 was phosphorylated by the proline-directed CDK2/CycA3 kinase on Thr231 (generating the AT180 epitope), Ser235, and equally on Thr212 and Thr217 in the Proline-rich region (Tau[Ser208-Gln244] or PRR). These modifications strongly decrease the capacity of TauF4 to polymerize tubulin into microtubules. While all the NMR parameters are consistent with a globally disordered Tau protein fragment, local clusters of structuration can be defined. The most salient result of our NMR analysis is that phosphorylation in the PRR stabilizes a short α-helix that runs from pSer235 till the very beginning of the microtubule-binding region (Tau[Thr245-Ser324] or MTBR of TauF4). Phosphorylation of Thr231/Ser235 creates a N-cap with helix stabilizing role while phosphorylation of Thr212/Thr217 does not induce modification of the local transient secondary structure, showing that the stabilizing effect is sequence specific. Using paramagnetic relaxation experiments, we additionally show a transient interaction between the PRR and the MTBR, observed in both TauF4 and phospho-TauF4. Proteins 2011;. © 2011 Wiley Periodicals, Inc.
Copyright © 2011 Wiley Periodicals, Inc.
Exosome-associated tau is secreted in tauopathy models and is selectively phosphorylated in cerebrospinal fluid (CSF) in early Alzheimer's Disease.
Source
University of Massachusetts Lowell, United States;
Abstract
Recent demonstrations that secretion, uptake, and interneuronal transfer of tau in tauopathy models can be modulated by disease-associated tau modifications suggest that secretion may be an element in the pathobiology of tau-induced neurodegeneration. Here we show that much of the tau secreted by M1C cells occurs via exosomal release, a widely characterized mechanism that mediates unconventional secretion of other aggregation-prone proteins (alpha synuclein, prion protein, and beta amyloid) in neurodegenerative disease. Exosome-associated tau is also present in human CSF samples, and is phosphorylated at Thr 181 (AT270), an established phosphotau biomarker for Alzheimer's Disease, in both M1C cells and CSF samples. A preliminary analysis of the proteins copurified with tau in secreted exosomes identified several that are known to be involved in disease-associated tau misprocessing. Our results therefore suggest that membrane trafficking pathways may play a significant role in the abnormal processing of tau that is not bound tomicrotubules.
Activity-dependent changes in cholinergic innervation of the mouse olfactory bulb.
Source
Department of Cell and Developmental Biology, University of Colorado, School of Medicine, Aurora, Colorado, United States of America.
Abstract
The interplay between olfactory activity and cholinergic modulation remains to be fully understood. This report examines the pattern of cholinergic innervation throughout the murine main olfactory bulb across different developmental stages and in naris-occluded animals. To visualize the pattern of cholinergic innervation, we used a transgenic mouse model, which expresses a fusion of the microtubule-associated protein, tau, with green fluorescence protein (GFP) under the control of the choline acetyltransferase (ChAT) promoter. This tau-GFP fusion product allows for a remarkably vivid and clear visualization of cholinergic innervation in the main olfactory bulb (MOB). Interestingly, we find an uneven distribution of GFP label in the adult glomerular layer (GL), where anterior, medial, and lateral glomerular regions of the bulb receive relatively heavier cholinergic innervation than other regions. In contrast to previous reports, we find a marked change in the pattern of cholinergic innervation to the GL following unilateral naris occlusion between the ipsilateral and contralateral bulbs in adult animals.
Vector-mediated expression of erythropoietin improves functional outcome after cervical spinal cord contusion injury.
Source
Department of Neurology, University of Michigan and VA Ann Arbor Healthcare System, Ann Arbor, MI, USA.
Abstract
We evaluated the therapeutic effect of erythropoietin (EPO) delivered by direct injection of a nonreplicating herpes simplex virus (HSV)-based vector coding for EPO (vEPO) in a model of cervical hemicord contusion at C7. At 1 h after spinal cord injury (SCI), either vEPO or control vector carrying a reporter gene (vC) was injected into the cord above and below the lesion. Animals injected with vEPO showed a statistically significant improvement in the ipsilateral forelimb function, as measured by open-field evaluation of motor performance, forelimb reaching in the cylinder test and misplacement in grid walk. This correlated with preservation of gray matter in the area of the lesion. There was also mild but significant improvement of hindlimb motor function measured by Basso-Beattie-Bresnahan score and computerized gait analysis in vEPO compared with control vector-injected animals. Microtubule-associated protein tau, phosphorylated and nonphosphorylated neurofilament protein and the synaptic proteins synaptophysin and PSD-95 were all significantly increased in the spinal cord of vEPO-treated animals compared with control vector-injected animals. These data suggest that gene transfer of EPO after cervical SCI by minimizing the injury size and enhancing tissue sparing preserves large-caliber axons and promotes synaptogenesis.Gene Therapy advance online publication, 3 November 2011; doi:10.1038/gt.2011.166.
Biomarkers predicting clinical benefit: fact or fiction?
Source
Department of Oncology, Hematology and Respiratory Diseases, University Hospital, University of Modena and Reggio Emilia, Modena 41100, Italy.
Abstract
Preoperative therapy is increasingly used in operable disease to improve the chance for breast-conservative surgery. Moreover, this strategy allows for a better definition of patient prognosis. Independently from stage at diagnosis and breast cancer subtype, the achievement of a pathological complete response (pCR) is a surrogate marker for long-term outcome. The likelihood of pCR depends on tumor biology, being poorly differentiated tumors with ductal histology, absence of hormone receptors, and high proliferation rate those with a higher chance of achieving a CR. However, pCR is a late efficacy parameter that can be evaluated at the end of the preoperative treatment; moreover, a pCR is achieved in a minority of patients and is not an appropriate efficacy measure for neoadjuvant endocrine therapy. The predictive role of tumor biomarkers such as p53, microtubule-associated tau protein, and poly (ADP-ribose) polymerase will be reviewed along with potential markers of early treatment effect.
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