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At least 19 recordsLinked to original sources

PubMed1977

Immunoflourescent staining of cytoplasmic and spindle microtubules in mouse fibroblasts with antibody to tau protein.

tau protein isolated from porcine brain microtubules was further purified by electrophoretic elution from polyacrylamide gels and used to prepare antisera in rabbits. The antiserum to tau specifically stains mitotic spindles and a filamentous network within mouse fibroblasts when the indirect immunofluorescence technique is used. The staining of the filamentous network and mitotic spindles is identical to that observed when cells are treated with antiserum prepared against electrophoretically purified tubulin. The filamentous network observed with either serum is sensitive to Colcemid. Absorption of anti-tau serum with electrophoretically purified tubulin does not remove the immunofluorescent staining of the mitotic spindle, whereas absorption with electrophoretically purified tau protein does. Conversely, absorption of antitubulin serum with tubulin eliminates its ability to stain the mitotic spindle, whereas absorption with tau has no effect. We conclude that tau protein and tubulin are antigenically distinct proteins and that tau is an integral part of microtubules in vivo. These results also provide evidence that tau protein, or an antigenically related protein, is associated with microtubules not only in brain but also in other cell types.

Animals↗

PubMed1979

Differences in surface morphology of microtubules reconstituted from pure brain tubulin using two different microtubule-associated proteins: the high molecular weight MAP 2 proteins and tau proteins.

Microtubules were reconstituted from homogeneous brain tubulin and homogeneous preparations of two different microtubule associated proteins, the high molecular weight MAP 2 proteins or the tau proteins. The resulting microtubules were characterized by three electron microscopical procedures: Thin sectional analysis of embeded material, negative staining analysis using a STEM microscope and high resolution metal-shadowing analysis. By all three procedures MAP 2 microtubules have a much rougher surface morphology than tau microtubules, in agreement with the much higher molecular weight of the MAP 2 proteins. Tau microtubules, however, do not show the very smooth surface of microtubules assembled from pure tubulin in the absence of any microtubule associated proteins. In the case of MAP 2 microtubules thin sectional analysis as well as metal shadowing reveals that the globular protrusions seen in negative staining analysis appear as linear side arms which may extend by as much as 30 nm on both sides from the microtubular wall proper, giving rise to an overall structure with a diameter close to 100 nm. The possible implication of such structures for in vivo situations is briefly discussed as is the possibility that the "halo-effect" around microtubules seen in vivo may be due to a structural organization similar to that of MAP 2 tubules in vitro.

Animals↗

PubMed2026

Lysine methylation is an endogenous post-translational modifications of tau protein in human brain and a modulator of aggregation propensity.

Tau protein undergoes a broad range of post-translational modifications in the brain, influencing its structure, solubility, and propensity to aggregate. This chapter presents an integrated methodological framework for characterizing tau methylation and evaluating its impact on tau biology. We describe procedures for isolating soluble and filamentous tau from post-mortem human brain tissue while preserving modifications for proteomic analysis. These approaches support precise mapping of methylation sites alongside other co-occurring modifications. To model methylation under controlled conditions, we outline protocols for recombinant tau expression, purification, and chemical reductive methylation, including radiolabeled assays for determining modification stoichiometry. We then detail biophysical assays used to assess how methylation alters tau conformation and aggregation propensity. This methodological framework supports experimentation seeking insight into mechanisms relevant to Alzheimer's disease and related tauopathies.

Humans↗

PubMed1978

Intracellular localization of the high molecular weight microtubule accessory protein by indirect immunofluorescence.

Microtubule accessory proteins were isolated from porcine brain microtubules by phosphocellulose chromatography, and the high molecular weight protein (HMW protein), purified from this microtubule-associated fraction by electrophoretic elution from SDS gels, was used to raise antisera in rabbits. In agarose double diffusion tests, the antiserum obtained forms precipitin lines with purified HMW protein but not with tau protein or tubulin. When rat glial cells (strain C6) are examined by indirect immunofluorescence, this serum specifically stains a colchicine-sensitive filamentous cytoplasmic network in interphase cells, a network indistinguishable from that seen when cells are treated with antitubulin serum. In dividing cells, specific staining of the mitotic spindle and the stem body is observed with the antiserum to HMW protein. These studies indicate that HMW protein, like tau protein, is associated with microtubules in intact cells.

Animals↗

PubMed1978

The non-tubulin component of microtubule protein oligomers. Effect on self-association and hydrodynamic properties.

We have investigated the association of non-tubulin microtubule proteins with tubulin to form the ring-shaped oligomeric structures found in microtubule preparations. We have found that the two oligomeric species present in our preparations of microtubule protein (s020,w = 18 and 30 S) each require non-tubulin factors for their formation. Two types of non-tubulin protein, the high molecular weight proteins (HMW) and the tau proteins were found to be active in ring formation. The HMW proteins promoted the formation of the 30 S oligomer, while the tau proteins promoted the formation of an oligomer of s020,w = 20 S. Analysis of the 30 S oligomer by gel filtration chromatography showed that the ratio of HMW proteins to tubulin was about twice that in the microtubule. The HMW proteins could be destroyed by exposure to trypsin, resulting in a marked increase in the sedimentation coefficient of the 30 S oligomer to 39 S. The 20, 30, and 39 S species were identified as rings by electron microscopy. The identity of the 18 S structure as a ring was called into question. Our data indicate that the 20 S species is a single ring and that the 30 S oligomer is a two-layered ring bearing HMW projections which contribute substantial hydrodynamic drag to the particle. We compare the organization of tubulin subunits and HMW molecules in the 30 S ring with the organization of these components in the microtubule and suggest that the organization in the ring is conserved in the microtubule.

Animals↗

PubMed2024

Lineage-specific splicing regulation of MAPT gene in the primate brain.

Divergence of precursor messenger RNA (pre-mRNA) alternative splicing (AS) is widespread in mammals, including primates, but the underlying mechanisms and functional impact are poorly understood. Here, we modeled cassette exon inclusion in primate brains as a quantitative trait and identified 1,170 (∼3%) exons with lineage-specific splicing shifts under stabilizing selection. Among them, microtubule-associated protein tau (MAPT) exons 2 and 10 underwent anticorrelated, two-step evolutionary shifts in the catarrhine and hominoid lineages, leading to their present inclusion levels in humans. The developmental-stage-specific divergence of exon 10 splicing, whose dysregulation can cause frontotemporal lobar degeneration (FTLD), is mediated by divergent distal intronic MBNL-binding sites. Competitive binding of these sites by CRISPR-dCas13d/gRNAs effectively reduces exon 10 inclusion, potentially providing a therapeutically compatible approach to modulate tau isoform expression. Our data suggest adaptation of MAPT function and, more generally, a role for AS in the evolutionary expansion of the primate brain.

tau Proteins↗

PubMed1979

Thyroid hormones and neurotubule assembly in vitro during brain development.

A new model has been used to evaluate the effects of thyroid hormones on brain development. This model is based on the assumption that the major effect of thyroid hormones is in regulating the rate of neurite growth of the rat brain at early stages of postnatal development. Microtubules were chosen as markers of neurite growth. We tested, therefore, whether the rate of microtubule assembly in vitro is under thyroid hormone control. The following results were obtained: The rate of tubulin assembly into microtubules in vitro seems to be thyroid hormone dependent: (a) in 15-day-old hypothyroid rats the rates of tubulin assembly in vitro are low, comparable to those levels found in normal rats on day 3; (b) normal rates of assembly in vitro are restored upon addition of very small amounts of microtubule fragments which act as nucleating centers in the process of microtubule formation; (c) addition of microtubule-associated proteins to a hypothyroid preparation restores maximal assembly rates; similar results were obtained on adding one of the microtubule-associated proteins (purified tau protein); (d) physiological amounts of thyroid hormones completely restore normal assembly rates provided that they are administered very early after birth; (e) the ability of tubulin to assemble maximally does not seem to be permanently impaired, since normal assembly rates are spontaneously restored when hypothyroidism is maintained until an adult stage; (f) normal microtubule assembly is observed when hypothyroidism is produced at an adult stage. The model which may be constructed from these results implies that thyroid hormones are required briefly after birth to accelerate the rate of microtubule assembly thus allowing intensive neurite growth during the critical period of brain development.

Aging↗

PubMed2024

Shaping human brain development and vulnerability through alternative splicing.

Alternative splicing contributes to shaping lineage-specific gene expression and phenotypes. In this issue of Cell Genomics, Recinos, Bao, Wang, et al.1 report that the balance between splicing isoforms of the microtubule-associated protein Tau in the brain is differentially regulated among primates by the RNA-binding protein MBNL2, with consequences for protein aggregation and neurodegeneration in humans.

Humans↗

PubMed1978

Fractionation of brain microtubule-associated proteins. Isolation of two different proteins which stimulate tubulin polymerization in vitro.

Two different tubulin-assembly-promoting proteins were isolated from porcine brain microtubule protein. Following a heat step performed on microtubule protein, the thermal-stable proteins were fractionated by chromatography on phosphocellulose and Sepharose 4B. Two highly purified associated proteins were obtained. One resembles the previously described MAP2 protein (polypeptide molecular weight approximately 300,000), the other a mixture of four or five polypeptides previously described as tau protein (molecular weights between 55,000 and 70,000). Both proteins stimulate the polymerization of pure brain tubulin into microtubules with comparable activity. The resulting microtubules were characterized by electron microscopical analysis. Microtubules polymerized in the presence of MAP2 protein show typical side projections, which are conspicuously absent in microtubules assembled in the presence of tau protein. The latter microtubules show smooth surfaces. Some biochemical similarities and differences between the two different microtubule-associated proteins are discussed.

Animals↗

PubMed2026

Riboregulation: a non-canonical tau function.

Almost since its discovery, tau protein has perplexed scientists and clinicians with its varied roles in physiology as well as its appearance as phosphorylated protein aggregates of various structures in many neurodegenerative diseases. Tau plays a role in microtubule stabilization, but from the earliest of studies, tau has also been observed to bind to RNA, with recent research suggesting tau has a higher affinity for some RNA species compared to microtubules. In the context of disease, tau dysfunction potentiates disruptions to RNA metabolism, including the perturbation of mRNA splicing, impairment of translation, de-repression of transposable elements, and alteration of RNA export and degradation. Tau aggregates directly sequester diverse RNA species and RNA binding proteins. Emerging evidence reinforces the characterization of tau as an RNA binding protein, highlighting questions about both the physiological and disease-related functions of this direct RNA binding. The disparate structure of tau in normal and various disease states makes teasing apart the various impacts on RNA and regulation a more difficult puzzle requiring future study. In this review, we summarize the evidence for tau's role in RNA biology, including as an RNA binding protein.

tau Proteins↗

PubMed2025

Elevated Cerebrospinal Fluid Total Tau in Niemann-Pick Disease Type C1: Correlation With Clinical Severity and Response to Therapeutic Interventions.

Niemann-Pick disease, type C1 (NPC1) is an inborn error of intracellular cholesterol transport. Impaired function of NPC1 leads to endolysosomal accumulation of unesterified cholesterol, which results in progressive neurodegeneration. Although the age of onset is variable, classical NPC1 is a pediatric disease. Identification of biomarkers that correlate with clinical phenotype and respond to therapeutic interventions will be essential for developing effective therapeutic interventions. Aβ peptides and Tau protein are primary components of amyloid plaques and neurofibrillary tangles, respectively, which are major pathological features in neurodegenerative disorders. Cerebrospinal fluid (CSF) levels of total Tau, a biomarker of axonal damage, were elevated ~3-fold (p < 0.0001) in 106 individuals with Niemann-Pick disease, type C1, relative to age-appropriate comparison samples. Baseline CSF total Tau levels correlated with clinical measures of disease severity. Specifically, CSF total Tau levels decreased with increased age of neurological onset (rs = -0.42, FDR adj. p < 0.0001) and increased with increased Annual Severity Increment Score (rs = 0.52, FDR adj. p < 0.0001). Baseline CSF total Tau levels were decreased 40% (p = 0.0066) in individuals being treated with miglustat, and longitudinal analysis substantiated this observation with a 40% decrease (p < 0.0001, 95% CI 32%-47.4%). Longitudinal analysis also showed a significant (p = 0.004) decrease of 19% (95% CI 7%-30%) in total Tau levels associated with intrathecal 2-hydroxypropyl-β-cyclodextrin therapy. These data show that CSF total Tau levels are significantly increased in individuals with NPC1, positively correlated with increased disease severity, and respond to therapeutic interventions.

Humans↗

PubMed2025

Tau uptake by human neurons depends on receptor LRP1 and kinase LRRK2.

Extracellular release and uptake of pathogenic forms of the microtubule-associated protein tau contribute to the pathogenesis of several neurodegenerative diseases, including Alzheimer's disease. Defining the cellular mechanisms and pathways for tau entry to human neurons is essential to understanding tauopathy pathogenesis and enabling the rational design of disease-modifying therapeutics. Here, whole-genome, loss-of-function CRISPR screens in human iPSC-derived excitatory neurons, the major neuronal cell type affected in these diseases, provide insights into the different cellular pathways for uptake of extracellular monomeric and fibrillar tau. Monomeric and fibrillar tau are both taken up by human neurons by receptor-mediated endocytosis, but involve different routes of entry at the neuronal surface: the low-density lipoprotein LRP1 is the primary receptor for monomeric tau, but contributes less to fibrillar tau entry. Similarly, endocytosis of monomeric tau is dependent on the familial Parkinson's disease gene LRRK2, but not required for endocytosis of fibrillar tau. These findings implicate LRP1 and LRRK2 in the pathogenesis of tauopathies and Parkinson's disease, and identify LRRK2 as a potential therapeutic target for altering progression of these diseases.

Humans↗

PubMed2026

The chromatin reader ZMYND8 recruits the NuRD component GATAD2A through its MYND domain to regulate MAPT213 long noncoding RNA transcription.

The zinc finger MYND-type containing eight protein (ZMYND8) is a chromatin reader that regulates neuronal gene expression by controlling the microtubule-associated protein tau (MAPT) locus. Here, we investigate how ZMYND8 regulates expression of the long non-coding RNA MAPT213 through its interaction with GATA zinc finger domain containing 2A (GATAD2A), a component of the Nucleosome Remodelling and Deacetylase complex. ZMYND8 exhibits opposite regulatory effects on protein-coding MAPT and non-coding MAPT213 transcripts in a manner dependent on its MYND domain, promoting MAPT expression while suppressing MAPT213 levels. Chromatin immunoprecipitation experiments demonstrated that ZMYND8 specifically recruits GATAD2A to the MAPT213 internal regulatory region, establishing a direct link between protein binding and transcriptional control. We determined the crystal structure of the ZMYND8 coiled-coil MYND domain at high resolution, revealing a homodimeric architecture. The MYND domain specifically recognizes GATAD2A through direct interaction with proline-rich motifs in GATAD2A's central region. Structure-function analysis identified critical binding interface residues, while quantitative measurements revealed moderate-affinity interactions enhanced through multivalent binding mechanisms. These findings establish the molecular basis for ZMYND8-mediated recruitment of chromatin remodeling complexes to specific genomic loci and provide a structural framework for understanding transcriptional regulation of MAPT213.

Humans↗

PubMed2026

A complex of MAST1 and 14-3-3η regulates Tau phosphorylation in the developing cortex.

The MAST family of serine/threonine kinases has been implicated in a spectrum of human neurodevelopmental disorders. However, little is known about their biological function or regulation. Seeking to fill these gaps in our knowledge, we have identified upstream and downstream partners of MAST1. 14-3-3η, a neuronal 14-3-3 paralog, specifically interacts with MAST1 at two regulatory serines, S90 and S161. p21-activated kinase (PAK), a neuronal regulator of the actin cytoskeleton, phosphorylates MAST1 to regulate its interaction with 14-3-3η. Exploiting mouse models of human Mega-Corpus-Callosum Syndrome (MCC) and whole brain phosphoproteomics, we identify the microtubule-associated protein Tau as a candidate substrate of MAST1. We show that pathogenic MAST1 mutations perturb protein function either through misfolding or attenuation of kinase activity. Our data are consistent with a model in which the MAST kinases couple PAK, a neuronal regulator of the actin cytoskeleton, to microtubule remodeling during the differentiation and specification of cortical neurons.

Animals↗

PubMed2026

An Integrative Proteomic Approach to Reveal Altered Signaling Modules During Alzheimer's Disease Progression in PS19 Tauopathy Mice.

Alzheimer's disease (AD) is a slowly progressive neurodegenerative disease that is characterized by cognitive, functional, and behavioral impairments. These changes occur owing to the progressive accumulation of extracellular amyloid-beta plaques and intracellular neurofibrillary tangles of hyperphosphorylated tau protein. AD is associated with the dysfunction of several essential neurotransmitter systems, such as dopamine, and impaired neurotransmission. Despite the association of neurotransmitter changes within the brain and AD pathology, in-depth profiling studies on neurotransmitters and their related proteomic changes are limited. This study was conducted to profile and integrate the proteomes and neurotransmitters in seven brain regions of PS19 (Tau P301S) mice according to AD progression between 4 and 7 months. Proteomic analysis revealed significantly altered canonical pathways in various brain regions, including metabolic abnormalities. In the neurotransmitter profile, we found significant alterations in the levels of six neurotransmitters-dopamine, serotonin, homovanillic acid, norepinephrine, 3-methoxytyramine, and 3,4-dihydroxyphenylacetic acid-during AD progression. Using an integrative approach between proteome and neurotransmitter profiles, we found that AD progression-dependent dopamine- and serotonin-related signaling modules are closely related to neurotransmitter changes, especially in the hippocampus and cerebellum. This integrative approach could provide new signaling modules to help understand AD progression and thereby enable improved treatment and clinical outcomes.

Animals↗

PubMed2026

Near-Infrared Fluorescent PROTAC Enables Theranostic Imaging and Selective Tau Degradation in Alzheimer's Disease.

The hyperphosphorylated Tau (p-Tau) protein plays a central role in the pathogenesis of Alzheimer's disease (AD) by driving neurofibrillary tangle formation and neuronal dysfunction. While proteolysis targeting chimeras (PROTACs) offer a promising approach for directly eliminating pathogenic proteins, their real-time visualization in living systems remains challenging. Here, we report the rational design and synthesis of a series of near-infrared (NIR) fluorescent Tau-targeting degraders that integrate theranostic imaging with targeted protein degradation. Among them, compound D9 emerges as a dual-functional degrader capable of both high-contrast fluorescence tracking and potent Tau clearance at 10 nM. Mechanistic investigations indicate that D9 induces Tau degradation through activation of the ubiquitin-proteasome system (UPS), as confirmed by inhibitor assays. Beyond Tau degradation, D9 also downregulates amyloid precursor protein (APP) and β-amyloid (Aβ) expression, suggesting broader neuroprotective effects. In in vivo studies, D9 significantly promotes p-Tau clearance and alleviates cognitive deficits in 3 ×Tg-AD mice. These findings demonstrate that D9 represents a first-in-class NIR fluorescent PROTAC for theranostic imaging and targeted degradation of Tau, providing a powerful platform for visualizing degradation dynamics and developing next-generation AD therapeutics.

Alzheimer's disease↗

PubMed1979

Competitive inhibition of colchicine binding to tubulin by microtubule-associated proteins.

Microtubule-associated proteins (MAPs) promote tubulin polymerization, whereas colchicine inhibits this process. In this paper, MAPs have been shown to inhibit colchicine binding to tubulin in a competitive manner. Attempts were made to identify which of the MAPs fraction(s) was responsible; both tau protein (a thermostable molecule with a molecular weight of approximately 70,000) and a high molecular weight fraction (HMW) were able to compete with colchicine. In contrast, Mg2+, which also induces microtubule assembly in vitro, had no effect on colchicine binding to tubulin.

Animals↗

PubMed1977

Microtubule assembly in vitro. Purification of assembly-promoting factors.

The role of microtubule-associated proteins in the assembly of tubulin to microtubules in vitro has been studied. 1. It has been confirmed that pure tubulin obtained by phosphocellulose column chromatography does not significantly assemble in vitro in the absence of minor components which co-polymerize with tubulin. Although tubulin aggregates in a morpholino-ethanesulfonate buffer containing high Mg2+ concentrations, this process was neither inhibited by Ca2+ or colchicine, nor reversed by cold exposure. 2. Microtubule-associated proteins were prepared, either by phosphocellulose column chromatography or by a direct method based on boiling reassembled microtubules in the presence of 2 mM dithiothreitol and 0.75 M NaCl. From each of these preparations two protein fractions were purified, either by Ultrogel ACA34 chromatography or by sucrose gradient ultracentrifugation. The first one, with a high molecular weight, did not promote tubulin assembly; ageing of this material did not induce any activity. On the other hand, the second fraction, with an apparent molecular weight of 70 000 (tau protein), when almost completely purified, was active in promoting assembly. Thus a single specific protein is able to promote assembly of pure tubulin.

Animals↗