03043nas a2200253 4500008004100000245008900041210006900130260000900199300000700208490000700215520224100222653001002463653001502473653002402488653001402512653001402526653002202540653001802562653001402580100001602594700002802610700003602638856011502674 2020 eng d00aPhagocytosis of full-length Tau oligomers by Actin-remodeling of activated microglia0 aPhagocytosis of fulllength Tau oligomers by Actinremodeling of a cJAN  a100 v173 a

Background Alzheimer's disease is associated with the accumulation of intracellular Tau tangles within neurons and extracellular amyloid-beta plaques in the brain parenchyma, which altogether results in synaptic loss and neurodegeneration. Extracellular concentrations of oligomers and aggregated proteins initiate microglial activation and convert their state of synaptic surveillance into a destructive inflammatory state. Although Tau oligomers have fleeting nature, they were shown to mediate neurotoxicity and microglial pro-inflammation. Due to the instability of oligomers, in vitro experiments become challenging, and hence, the stability of the full-length Tau oligomers is a major concern. Methods In this study, we have prepared and stabilized hTau40(WT) oligomers, which were purified by size-exclusion chromatography. The formation of the oligomers was confirmed by western blot, thioflavin-S, 8-anilinonaphthaalene-1-sulfonic acid fluorescence, and circular dichroism spectroscopy, which determine the intermolecular cross-beta sheet structure and hydrophobicity. The efficiency of N9 microglial cells to phagocytose hTau40(WT) oligomer and subsequent microglial activation was studied by immunofluorescence microscopy with apotome. The one-way ANOVA was performed for the statistical analysis of fluorometric assay and microscopic analysis. Results Full-length Tau oligomers were detected in heterogeneous globular structures ranging from 5 to 50 nm as observed by high-resolution transmission electron microscopy, which was further characterized by oligomer-specific A11 antibody. Immunocytochemistry studies for oligomer treatment were evidenced with A11(+) Iba1(high) microglia, suggesting that the phagocytosis of extracellular Tau oligomers leads to microglial activation. Also, the microglia were observed with remodeled filopodia-like actin structures upon the exposure of oligomers and aggregated Tau. Conclusion The peri-membrane polymerization of actin filament and co-localization of Iba1 relate to the microglial movements for phagocytosis. Here, these findings suggest that microglia modified actin cytoskeleton for phagocytosis and rapid clearance of Tau oligomers in Alzheimer's disease condition.

10aActin10aactivation10aAlzheimer's disease10amicroglia10amigration10aneurodegeneration10aTau Oligomers10aTauopathy1 aDas, Rashmi1 aBalmik, Abhishek, Ankur1 aChinnathambi, Subashchandrabose uhttps://library.ncl.res.in/content/phagocytosis-full-length-tau-oligomers-actin-remodeling-activated-microglia02930nas a2200217 4500008004100000245010400041210006900145260000900214300000700223490000700230520216300237653002402400653001402424653002002438653001902458653001802477100002902495700002602524700003602550856012602586 2021 eng d00aBaicalein inhibits heparin-induced Tau aggregation by initializing non-toxic Tau oligomer formation0 aBaicalein inhibits heparininduced Tau aggregation by initializin cFEB  a160 v193 a

Background: Amyloid aggregate deposition is the key feature of Alzheimer's disease. The proteinaceous aggregates found in the afflicted brain are the intra-neuronal neurofibrillary tangles formed by the microtubule-associated protein Tau and extracellular deposits, senile plaques, of amyloid beta (A beta) peptide proteolytically derived from the amyloid precursor protein. Accumulation of these aggregates has manifestations in the later stages of the disease, such as memory loss and cognitive inabilities originating from the neuronal dysfunction, neurodegeneration, and brain atrophy. Treatment of this disease at the late stages is difficult, and many clinical trials have failed. Hence, the goal is to find means capable of preventing the aggregation of these intrinsically disordered proteins by inhibiting the early stages of their pathological transformations. Polyphenols are known to be neuroprotective agents with the noticeable potential against many neurodegenerative diseases, such as Alzheimer's, Parkinson's, and Prion diseases. Methods: We analyzed the capability of Baicalein to inhibit aggregation of human Tau protein by a multifactorial analysis that included several biophysical and biochemical techniques. Results: The potency of Baicalein, a polyphenol from the Scutellaria baicalensis Georgi, against in vitro Tau aggregation and PHF dissolution has been screened and validated. ThS fluorescence assay revealed the potent inhibitory activity of Baicalein, whereas ANS revealed its mechanism of Tau inhibition viz. by oligomer capture and dissociation. In addition, Baicalein dissolved the preformed mature fibrils of Tau thereby possessing a dual target action. Tau oligomers formed by Baicalein were non-toxic to neuronal cells, highlighting its role as a potent molecule to be screened against AD. Conclusion: In conclusion, Baicalein inhibits aggregation of hTau40 by enhancing the formation of SDS-stable oligomers and preventing fibril formation. Baicalein-induced oligomers do not affect the viability of the neuroblastoma cells. Therefore, Baicalein can be considered as a lead molecule against Tau pathology in AD.

10aAlzheimer's disease10aBaicalein10aTau dissolution10aTau inhibition10aTau Oligomers1 aSonawane, Shweta, Kishor1 aUversky, Vladimir, N.1 aChinnathambi, Subashchandrabose uhttps://library.ncl.res.in/content/baicalein-inhibits-heparin-induced-tau-aggregation-initializing-non-toxic-tau-oligomer02423nas a2200241 4500008004100000022001400041245012900055210006900184260000800253300001200261490000700273520160700280653002101887653001901908653001501927653001401942653001401956653001401970653001801984100001602002700003602018856012702054 2021 eng d a1398-921900aMicroglial remodeling of actin network by Tau oligomers, via G protein-coupled purinergic receptor, P2Y12R-driven chemotaxis0 aMicroglial remodeling of actin network by Tau oligomers via G pr cMAY a153-1700 v223 a

Alzheimer's disease (AD) is associated with age-related neurodegeneration, synaptic deformation and chronic inflammation mediated by microglia and infiltrated macrophages in the brain. Tau oligomers can be released from damaged neurons via various mechanisms such as exosomes, neurotransmitter, membrane leakage etc. Microglia sense the extracellular Tau through several cell-surface receptors and mediate chemotaxis and phagocytosis. The purinergic receptor P2Y12R recently gained interest in neurodegeneration for neuro-glial communication and microglial chemotaxis towards the site of plaque deposition. To understand the effect of extracellular Tau oligomers in microglial migration, the P2Y12R-mediated actin remodeling, reorientation of tubulin network and rate of migration were studied in the presence of ATP. The extracellular Tau species directly interacted with P2Y12R and also induced this purinoceptor expression in microglia. Microglial P2Y12R colocalized with remodeled membrane-associated actin network as a component of migration in response to Tau oligomers. As an inducer of P2Y12R, ATP facilitated the localization of P2Y12R in lamellipodia and filopodia during accelerated microglial migration. The direct interaction of extracellular Tau oligomers with microglial P2Y12R would facilitate the signal transduction in both way, directional chemotaxis and receptor-mediated phagocytosis. These unprecedented findings emphasize that microglia can modulate the membrane-associated actin structure and incorporate P2Y12R to perceive the axis and rate of chemotaxis in Tauopathy.

10aactin remodeling10aAlzheimer&apos10achemotaxis10amicroglia10amigration10as disease10aTau Oligomers1 aDas, Rashmi1 aChinnathambi, Subashchandrabose uhttps://library.ncl.res.in/content/microglial-remodeling-actin-network-tau-oligomers-g-protein-coupled-purinergic-receptor02228nas a2200217 4500008004100000022001400041245006100055210006100116260000800177300001400185490000700199520152900206653003201735653002901767653002001796653001801816653001601834100003401850700003601884856009001920 2022 eng d a0739-110200aRole of cysteines in accelerating Tau filament formation0 aRole of cysteines in accelerating Tau filament formation cJUN a4366-43750 v403 a

Alzheimer's disease is majorly associated with intracellular accumulation of Tau into paired helical filaments and tangles. The self-aggregated dimeric and oligomeric species of Tau formed are more toxic to neuronal cells and acts as seeds for filament formation. The two cysteine residues and the two hexapeptide regions of full-length Tau play a key role in initialization and filament formation during Tau aggregation. The role of cysteine residues in Tau aggregation has been studied by in-vitro aggregation assay that was measured by Thioflavin S fluorescence to observe the kinetics of aggregation. In this study, we have performed in-vitro aggregation assay with recombinant full-length Tau and the cysteine mutants to understand the mechanism of cysteine independent Tau aggregation. Here, we report that cysteine mutant full-length Tau can aggregate to form filaments under in-vitro conditions. To visualize the polymorphisms of Tau and cysteine mutants under different aggregation conditions anionic cofactor, heparin was employed. Wild-type Tau showed rapid aggregation to form oligomers and filaments. On the other hand, the cysteine mutant delayed the initial Tau aggregation. This indicates the importance of cysteine residues in accelerating initial Tau nucleation for its aggregation. The filament morphology of wild-type and cysteine mutant Tau has been characterized using transmission electron microscopy and high-resolution transmission electron microscopy. Communicated by Ramaswamy H. Sarma

10aHeparin-induced aggregation10aPaired helical filaments10aTau Aggregation10aTau Oligomers10atau protein1 aChidambaram, Hariharakrishnan1 aChinnathambi, Subashchandrabose uhttps://library.ncl.res.in/content/role-cysteines-accelerating-tau-filament-formation02637nas a2200205 4500008004100000245013100041210006900172260000800241300000700249490000700256520191300263653001402176653001402190653001402204653001302218653001802231100003602249700001602285856013002301 2023 eng d00aMicroglia degrade Tau oligomers deposit via purinergic P2Y12-associated podosome and filopodia formation and induce chemotaxis0 aMicroglia degrade Tau oligomers deposit via purinergic P2Y12asso cMAY a950 v133 a

BackgroundTau protein forms neurofibrillary tangles and becomes deposited in the brain during Alzheimer's disease (AD). Tau oligomers are the most reactive species, mediating neurotoxic and inflammatory activity. Microglia are the immune cells in the central nervous system, sense the extracellular Tau via various cell surface receptors. Purinergic P2Y12 receptor can directly interact with Tau oligomers and mediates microglial chemotaxis via actin remodeling. The disease-associated microglia are associated with impaired migration and express a reduced level of P2Y12, but elevate the level of reactive oxygen species and pro-inflammatory cytokines.ResultsHere, we studied the formation and organization of various actin microstructures such as-podosome, filopodia and uropod in colocalization with actin nucleator protein Arp2 and scaffold protein TKS5 in Tau-induced microglia by fluorescence microscopy. Further, the relevance of P2Y12 signaling either by activation or blockage was studied in terms of actin structure formations and Tau deposits degradation by N9 microglia. Extracellular Tau oligomers facilitate the microglial migration via Arp2-associated podosome and filopodia formation through the involvement of P2Y12 signaling. Similarly, Tau oligomers induce the TKS5-associated podosome clustering in microglial lamella in a time-dependent manner. Moreover, the P2Y12 was evidenced to localize with F-actin-rich podosome and filopodia during Tau-deposit degradation. The blockage of P2Y12 signaling resulted in decreased microglial migration and Tau-deposit degradation.ConclusionsThe P2Y12 signaling mediate the formation of migratory actin structures like- podosome and filopodia to exhibit chemotaxis and degrade Tau deposit. These beneficial roles of P2Y12 in microglial chemotaxis, actin network remodeling and Tau clearance can be intervened as a therapeutic target in AD.

10aFilopodia10amicroglia10amigration10aPodosome10aTau Oligomers1 aChinnathambi, Subashchandrabose1 aDas, Rashmi uhttps://library.ncl.res.in/content/microglia-degrade-tau-oligomers-deposit-purinergic-p2y12-associated-podosome-and-filopodia