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Jose Abisambra,
Umesh K Jinwal,
Yoshinari Miyata,
Justin Rogers,
Laura Blair,
Xiaokai Li,
Sandlin P Seguin,
Li Wang,
Ying Jin,
Justin Bacon, [......],
Juan Zhang,
John Koren,
Zapporah T Young,
Christopher A Atkins, Bo Zhang,
Lisa Y Lawson,
Edwin J Weeber,
Jeffrey L Brodsky,
Jason E Gestwicki,
Chad A Dickey
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ABSTRACT: BACKGROUND: The microtubule-associated protein tau accumulates in neurodegenerative diseases known as tauopathies, the most common being Alzheimer's disease. One way to treat these disorders may be to reduce abnormal tau levels through chaperone manipulation, thus subverting synaptic plasticity defects caused by tau's toxic accretion. METHODS: Tauopathy models were used to study the impact of YM-01 on tau. YM-01 is an allosteric promoter of triage functions of the most abundant variant of the heat shock protein 70 (Hsp70) family in the brain, heat shock cognate 70 protein (Hsc70). The mechanisms by which YM-01 modified Hsc70 activity and tau stability were evaluated with biochemical methods, cell cultures, and primary neuronal cultures from tau transgenic mice. YM-01 was also administered to acute brain slices of tau mice; changes in tau stability and electrophysiological correlates of learning and memory were measured. RESULTS: Tau levels were rapidly and potently reduced in vitro and ex vivo upon treatment with nanomolar concentrations of YM-01. Consistent with Hsc70 having a key role in this process, overexpression of heat shock protein 40 (DNAJB2), an Hsp70 co-chaperone, suppressed YM-01 activity. In contrast to its effects in pathogenic tauopathy models, YM-01 had little activity in ex vivo brain slices from normal, wild-type mice unless microtubules were disrupted, suggesting that Hsc70 acts preferentially on abnormal pools of free tau. Finally, treatment with YM-01 increased long-term potentiation in tau transgenic brain slices. CONCLUSIONS: Therapeutics that exploit the ability of chaperones to selectively target abnormal tau can rapidly and potently rescue the synaptic dysfunction that occurs in Alzheimer's disease and other tauopathies.
Biological psychiatry 04/2013; · 8.93 Impact Factor
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Umesh K Jinwal,
Elias Akoury,
Jose F Abisambra,
John C O'Leary,
Andrea D Thompson,
Laura J Blair,
Ying Jin,
Justin Bacon,
Bryce A Nordhues,
Matthew Cockman,
Juan Zhang,
Pengfei Li, Bo Zhang,
Sergiy Borysov,
Vladimir N Uversky,
Jacek Biernat,
Eckhard Mandelkow,
Jason E Gestwicki,
Markus Zweckstetter,
Chad A Dickey
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ABSTRACT: Dysfunctional tau accumulation is a major contributing factor in tauopathies, and the heat-shock protein 70 (Hsp70) seems to play an important role in this accumulation. Several reports suggest that Hsp70 proteins can cause tau degradation to be accelerated or slowed, but how these opposing activities are controlled is unclear. Here we demonstrate that highly homologous variants in the Hsp70 family can have opposing effects on tau clearance kinetics. When overexpressed in a tetracycline (Tet)-based protein chase model, constitutive heat shock cognate 70 (Hsc70) and inducible Hsp72 slowed or accelerated tau clearance, respectively. Tau synergized with Hsc70, but not Hsp72, to promote microtubule assembly at nearly twice the rate of either Hsp70 homologue in reconstituted, ATP-regenerating Xenopus extracts supplemented with rhodamine-labeled tubulin and human recombinant Hsp72 and Hsc70. Nuclear magnetic resonance spectroscopy with human recombinant protein revealed that Hsp72 had greater affinity for tau than Hsc70 (I/I(0) ratio difference of 0.3), but Hsc70 was 30 times more abundant than Hsp72 in human and mouse brain tissue. This indicates that the predominant Hsp70 variant in the brain is Hsc70, suggesting that the brain environment primarily supports slower tau clearance. Despite its capacity to clear tau, Hsp72 was not induced in the Alzheimer's disease brain, suggesting a mechanism for age-associated onset of the disease. Through the use of chimeras that blended the domains of Hsp72 and Hsc70, we determined that the reason for these differences between Hsc70 and Hsp72 with regard to tau clearance kinetics lies within their C-terminal domains, which are essential for their interactions with substrates and cochaperones. Hsp72 but not Hsc70 in the presence of tau was able to recruit the cochaperone ubiquitin ligase CHIP, which is known to facilitate the ubiquitination of tau, describing a possible mechanism of how the C-termini of these homologous Hsp70 variants can differentially regulate tau triage. Thus, efforts to promote Hsp72 expression and inhibit Hsc70 could be therapeutically relevant for tauopathies.-Jinwal, U. K., Akoury, E., Abisambra, J. F., O'Leary, J. C., III, Thompson, A. D., Blair, L. J., Jin, Y., Bacon, J., Nordhues, B. A., Cockman, M., Zhang, J., Li, P., Zhang, B., Borysov, S., Uversky, V. N., Biernat, J., Mandelkow, E., Gestwicki, J. E., Zweckstetter, M., Dickey, C. A. Imbalance of Hsp70 family variants fosters tau accumulation.
The FASEB Journal 12/2012; · 5.71 Impact Factor
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Amirthaa Suntharalingam,
Jose F Abisambra,
John C O'Leary,
John Koren, Bo Zhang,
Myung Kuk Joe,
Laura J Blair,
Shannon E Hill,
Umesh K Jinwal,
Matthew Cockman,
Adam S Duerfeldt,
Stanislav Tomarev,
Brian S J Blagg,
Raquel L Lieberman,
Chad A Dickey
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ABSTRACT: Clearance of misfolded proteins in the endoplasmic reticulum (ER) is traditionally handled by ER-associated degradation, a process that requires retro-translocation and ubiquitination mediated by a lumenal chaperone network. Here we investigated whether the secreted, glaucoma-associated protein myocilin was processed by this pathway. Myocilin is typically transported through the ER/Golgi network, but inherited mutations in myocilin lead to its misfolding and aggregation within trabecular meshwork cells, and ultimately, ER-stress induced cell death. Using targeted knockdown strategies, we determined that Grp94, the ER equivalent of Hsp90, specifically recognizes mutant myocilin, triaging it through ERAD. The addition of mutant myocilin to the short list of Grp94 clients strengthens the hypothesis that beta-strand secondary structure drives client association with Grp94. Interestingly, the ERAD pathway is incapable of efficiently handling the removal of mutant myocilin, but when Grp94 is depleted, degradation of mutant myocilin is shunted away from ERAD towards a more robust clearance pathway for aggregation-prone proteins, the autophagy system. Thus ERAD inefficiency for distinct aggregation-prone proteins can be subverted by manipulating ER chaperones, leading to more effective clearance by the autophagic/lysosomal pathway. General Hsp90 inhibitors and a selective Grp94 inhibitor also facilitate clearance of mutant myocilin, suggesting that therapeutic approaches aimed at inhibiting Grp94 could be beneficial for patients suffering from some cases of myocilin glaucoma.
Journal of Biological Chemistry 10/2012; · 4.77 Impact Factor
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ABSTRACT: In the bacterial ISC system for iron-sulfur cluster assembly, IscU acts as a primary scaffold protein, and the molecular co-chaperones HscA and HscB specifically interact with IscU to facilitate ATP-driven cluster transfer. In this work, cluster transfer from Azotobacter vinelandii [Fe(2)S(2)](2+) cluster-bound IscU to apo-Grx5, a general purpose monothiol glutaredoxin in A. vinelandii, was monitored by circular dichroism spectroscopy, in the absence and in the presence of HscA/HscB/Mg-ATP. The results indicate a 700-fold enhancement in the rate of [Fe(2)S(2)](2+) cluster transfer in the presence of the co-chaperones and Mg-ATP, yielding a second-order rate constant of 20 000 M(-1) min(-1) at 23 °C. Thus, HscA and HscB are required for efficient ATP-dependent [Fe(2)S(2)](2+) cluster transfer from IscU to Grx5. The results support a role for monothiol Grx's in storing and transporting [Fe(2)S(2)](2+) clusters assembled on IscU and illustrate the limitations of interpreting in vitro cluster transfer studies involving [Fe(2)S(2)]-IscU in the absence of the dedicated HscA/HscB co-chaperone system.
Journal of the American Chemical Society 09/2012; 134(37):15213-6. · 9.91 Impact Factor
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Nature Nanotechnology 09/2012; 7(10):615-6. · 27.27 Impact Factor
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ABSTRACT: The ideal cells for tissue engineering should have such characteristics as easy obtainment, safety, immune privilege, the capability of self-renewal and multipotency. Adipose-derived stem cells (ADSCs) are a promising candidate. But the immunogenicity of allogeneic mesenchymal stem cells limits their longterm benefits. In this study, we introduced human cytomegalovirus US2/US3 gene into the ADSCs to decrease the expression of MHC I protein of ADSCs and reduce the activation of T cells of the recipient animals. Moreover, the biosafety and biological characteristics of ADSCs transfected with the US2/US3 genes (ADSCs-US2/US3) were similar to normal ADSCs. Then we took ADSCs-US2/US3 to construct tissue engineered bone for repairing bone defects in pigs and found that there were no great differences in repair effects or healing time between the allogeneic ADSCs-US2/US3 group and the autologous ADSCs group. These results suggest that allogeneic ADSCs-US2/US3 have the advantages of biological safety, low immunogenicity, and effective osteogenesis. Such barely immunogenic ADSCs will be crucial for the success of future tissue regenerative approaches.
Cell Transplantation 09/2012; · 5.13 Impact Factor
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ABSTRACT: Alzheimer's disease (AD) is a neurodegenerative disorder and the most common form of dementia, affecting more than 5.4 million people in the USA. Although the cause of AD is not well understood, the cholinergic, amyloid and tau hypotheses were proposed to explain its development. Drug discovery for AD based on the cholinergic and amyloid theories have not been effective. In this article we summarize tau-based natural products as AD therapeutics from a variety of biological sources, including the anti-amyloid agent curcumin, isolated from turmeric, the microtubule stabilizer paclitaxel, from the Pacific Yew Taxus brevifolia, and the Streptomyces-derived Hsp90 inhibitor, geldanamycin. The overlooked approach of clearing tau aggregation will most likely be the next objective for AD drug discovery.
Future medicinal chemistry 09/2012; 4(13):1751-61. · 2.52 Impact Factor
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ABSTRACT: Tau aggregation and amyloidogenesis are common hallmarks for neurodegenerative disorders called tauopathies. The molecular chaperone network constitutes the cellular defense against insults such as tau aggregation. However, chaperone effects on tau are dichotomous. Loss of tau's microtubule-binding activity facilitates an inappropriate chaperone interaction that promotes an amyloidogenic tau conformation. Conversely, other chaperones are capable of promoting tau clearance. Here, we demonstrate that a critical contributor to tau triage is the DnaJ-binding domain of Hsp70 proteins. In particular, over-expression of the constitutive DnaJ, DnaJA1, mediated tau clearance, while knockdown facilitated tau accumulation. This clearance was not specific to distinct pathogenic tau species. The activity of DnaJA1 was attenuated by concomitant increases in Hsp70. Tau reductions facilitated by DnaJA1 were dependent on the integrity of lysines known to be poly-ubiquitinated in human Alzheimer's brain. In vivo, DnaJA1 and tau levels were inversely correlated. The effects of DnaJA1 were partially specific: DnaJA1 reduced the levels of a polyQ protein but had no significant effect on α-synuclein levels. These data suggest that DnaJA1 triages all tau species for ubiquitin-dependent clearance mechanisms. Moreover, the levels of DnaJA1 and Hsp70 seem to play against each other with regard to tau: as DnaJA1 levels increase, tau levels are reduced, but this can be prevented if Hsp70 levels are simultaneously induced. Thus, the DnaJ repertoire possibly represents a powerful set of genetic modifiers for tau pathogenesis. Further investigations could provide new insights about triage decisions that facilitate or prevent amyloidogenesis of tau and other proteins associated with neurodegenerative disease.
Journal of Molecular Biology 02/2012; 421(4-5):653-61. · 4.00 Impact Factor
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ABSTRACT: We have used density functional theory (DFT) employing several different exchange-correlation functionals (PW91, PBE, PBEsol, TPSS, and revTPSS) coupled with lattice dynamics calculations to compute the thermodynamics of CO(2) absorption/desorption reactions for selected transition metal oxides, (TMO), and hydroxides, TM(OH)(2), where TM = Mn, Ni, Zn, and Cd. The van't Hoff plots, which describe the reaction equilibrium as a function of the partial pressures of CO(2) and H(2)O as well as temperature, were computed from DFT total energies, complemented by the free energy contribution of solids and gases from lattice dynamics and statistical mechanics, respectively. We find that the PBEsol functional calculations are generally in better agreement with experimental phase equilibrium data compared with the other functionals we tested. In contrast, the formation enthalpies of the compounds are better computed with the TPSS and revTPSS functionals. The PBEsol functional gives better equilibrium properties due to a partial cancellation of errors in the enthalpies of formation. We have identified all CO(2) capture reactions that lie on the Gibbs free energy convex hull as a function of temperature and the partial pressures of CO(2) and H(2)O for all TMO and TM(OH)(2) systems studied here.
The Journal of chemical physics 02/2012; 136(6):064516. · 3.09 Impact Factor
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ABSTRACT: Sodium β-alumina (SBA)-based gate dielectric films have been developed for all solution-processed, transparent and low voltage field-effect transistors (FETs). Its high dielectric constant has been ascribed to sodium (Na+) ions in the crystal structure; however, there are no published experimental results concerning the contribution of Na+ ions to the dielectric behavior, and the degree of crystallinity of the thin films. In addition, as an ionic conductor, β-alumina could give rise to some issues such as leakage current caused by Na diffusion, threshold voltage shift due to interface charge accumulation and longer response time due to slower polarization of the Na+ ions. This paper will address these issues using zinc tin oxide (ZTO) FETs, and propose possible measures to further improve SBA-based gate materials for electronic devices.
ACS Applied Materials & Interfaces 11/2011; 3(11):4254-61. · 4.53 Impact Factor
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Advanced Functional Materials 12/2010; 21(1):29 - 45. · 10.18 Impact Factor
