Max Planck Unit for Structural Molecular Biology

Hamburg, Japan

Max Planck Unit for Structural Molecular Biology

Hamburg, Japan
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Bulic B.,Center for Advanced European Studies and Research | Pickhardt M.,Max Planck Unit for Structural Molecular Biology | Mandelkow E.-M.,Max Planck Unit for Structural Molecular Biology | Mandelkow E.,Max Planck Unit for Structural Molecular Biology
Neuropharmacology | Year: 2010

Alzheimer disease is characterized by pathological aggregation of two proteins, tau and Aβ-amyloid, both of which are considered to be toxic to neurons. In this review we summarize recent advances on small molecule inhibitors of protein aggregation with emphasis on tau, with activities mediated by the direct interference of self-assembly. The inhibitors can be clustered in several compound classes according to their chemical structure, with subsequent description of the structure-activity relationships, showing that hydrophobic interactions are prevailing. The description is extended to the pharmacological profile of the compounds in order to evaluate their drug-likeness, with special attention to toxicity and bioavailability. The collected data indicate that following the improvements of the in vitro inhibitory potencies, the consideration of the in vivo pharmacokinetics is an absolute prerequisite for the development of compounds suitable for a transfer from bench to bedside. © 2010 Elsevier Ltd.

Schirmer R.H.,University of Heidelberg | Adler H.,University of Heidelberg | Pickhardt M.,Max Planck Unit for Structural Molecular Biology | Pickhardt M.,German Center for Neurodegenerative Diseases | And 2 more authors.
Neurobiology of Aging | Year: 2011

Methylene blue (MB), the first synthetic drug, has a 120-year-long history of diverse applications, both in medical treatments and as a staining reagent. In recent years there was a surge of interest in MB as an antimalarial agent and as a potential treatment of neurodegenerative disorders such as Alzheimer's disease (AD), possibly through its inhibition of the aggregation of tau protein. Here we review the history and medical applications of MB, with emphasis on recent developments. © 2011 Elsevier Inc.

Sydow A.,Max Planck Unit for Structural Molecular Biology | Mandelkow E.-M.,Max Planck Unit for Structural Molecular Biology
Neurodegenerative Diseases | Year: 2010

Background: Aggregates of the tau protein are a hallmark of Alzheimer's and several other neurodegenerative diseases. Various transgenic mouse models have been generated to study the aggregation process. Since wild-type tau is highly soluble and does not aggregate readily, most models make use of tau mutations that occur in human frontotemporal dementias and are more prone to aggregate. These mouse models show neurofibrillary tangles similar to those of Alzheimer's disease. However, since the mice contain both endogenous wild-type mouse tau and exogenous human mutant tau, the relative contribution of these components to the aggregates has been a matter of debate. Objective:Using a new set of regulatable transgenic mouse models, we sought to determine whether mouse tau coaggregates with human tau when it is switched on. Furthermore, we asked what type of tau remains in the aggregates after switching off the expression of exogenous tau. Methods: We generated doxycycline-inducible transgenic mice expressing either full-length human tau or the tau repeat domain (tau RD). In addition, both types of human tau derivatives were expressed in a 'proaggregant' form (with the frontotemporal dementia with parkinsonism linked to chromosome 17 mutation ΔK280), or in an 'antiaggregant' form (with additional proline mutations to block β-structure and aggregation). Results:The proaggregant tauRD mice develop tangles rapidly after induction, the antiaggregant mice do not. Analysis by biochemistry and immunohistology reveals that the tangles contain both exogenous and endogenous mouse tau. After switching off the proaggregant tauRD, tangles persist for extended periods. However, they are composed entirely of mouse tau. Conclusions:Mouse tau and exogenous human tau can coaggregate in transgenic models of tauopathy. The aggregates are in dynamic equilibrium with their subunits, so that exogenous tau disappears when its expression is switched off. Once the seeds of aggregation are generated by the foreign tau species, they propagate in a 'prion-like' fashion within the cell even after the foreign tau has disappeared. Copyright © 2010 S. Karger AG, Basel.

Kruger U.,Max Planck Unit for Structural Molecular Biology | Kruger U.,German Center for Neurodegenerative Diseases | Wang Y.,Max Planck Unit for Structural Molecular Biology | Wang Y.,German Center for Neurodegenerative Diseases | And 4 more authors.
Neurobiology of Aging | Year: 2012

Modulating the tau level may represent a therapeutic target for Alzheimer's disease (AD), as accumulating evidence shows that Abeta-induced neurodegeneration is mediated by tau. It is therefore important to understand the expression and degradation of tau in neurons. Recently we showed that overexpressed mutant tau and tau aggregates are degraded via the autophagic pathway in an N2a cell model. Here we investigated whether autophagy is involved in the degradation of endogenous tau in cultured primary neurons. We activated this pathway in primary neurons with trehalose, an enhancer of autophagy. This resulted in the reduction of endogenous tau protein. Tau phosphorylation at several sites elevated in AD pathology had little influence on its degradation by autophagy. Furthermore, by using a neuronal cell model of tauopathy, we showed that activation of autophagy suppresses tau aggregation and eliminates cytotoxicity. Notably, apart from activating autophagy, trehalose also inhibits tau aggregation directly. Thus, trehalose may be a good candidate for developing therapeutic strategies for AD and other tauopathies. © 2012 Elsevier Inc.

Holtzman D.M.,University of Washington | Mandelkow E.,Max Planck Unit for Structural Molecular Biology | Mandelkow E.,German Center for Neurodegenerative Diseases | Selkoe D.J.,Harvard University
Cold Spring Harbor Perspectives in Biology | Year: 2012

Remarkable advances in unraveling the biological underpinnings of Alzheimer disease (AD) have occurred during the last 25 years. Despite this,we have made only the smallest of dents in the development of truly disease-modifying treatments. What will change over the next 10 years? While the answer is not clear, we make several predictions on the state of the field in 2020, based on the rich knowledge described in the other contributions in this collection. As such, our predictions represent some of the principal unresolved questions that we believe deserve special investigative attention in the coming decade. © 2012 Cold Spring Harbor Laboratory Press; all rights reserved.

Garg S.,Max Planck Unit for Structural Molecular Biology | Timm T.,Max Planck Unit for Structural Molecular Biology | Mandelkow E.-M.,Max Planck Unit for Structural Molecular Biology | Mandelkow E.-M.,German Center for Neurodegenerative Diseases | And 3 more authors.
Neurobiology of Aging | Year: 2011

The amyloid cascade hypothesis of Alzheimer's disease (AD) posits that the generation of β-amyloid (Aβ) triggers Tau neurofibrillary pathology. Recently a "17 kD" calpain-induced Tau fragment, comprising residues 45-230 (molecular weight [MW], 18.7 kD), was proposed to mediate Aβ-induced toxicity. Here, we demonstrate that the "17 kD" fragment is actually much smaller, containing residues 125-230 (molecular weight, 10.7 kD). Inducing Tau phosphorylation by okadaic acid or mimicking phosphorylation by Glu mutations at the epitopes of Alzheimer-diagnostic antibodies AT100/AT8/PHF1 could not prevent the generation of this fragment. The fragment can be induced not only by Aβ oligomers, but also by other cell stressors, e.g., thapsigargin (a Ca2+-ATPase inhibitor) or glutamate (an excitatory neurotransmitter). However, overexpression of neither Tau45-230 nor Tau125-230 fragment is toxic to Chinese hamster ovary (CHO) cells, neuroblastoma cells (N2a) or primary hippocampal neurons. Finally, the calpain-induced fragment can be observed both in Alzheimer's disease brains and in control normal human brains. We conclude that the 17 kD Tau fragment is not a mediator of Aβ-induced toxicity, leaving open the possibility that upstream calpain activation might cause both Tau fragmentation and toxicity. © 2010 Elsevier Inc.

Swaminathan R.,Indian Institute of Technology Guwahati | Ravi V.K.,Indian Institute of Technology Guwahati | Kumar S.,Max Planck Unit for Structural Molecular Biology | Kumar M.V.S.,Indian Institute of Science | Chandra N.,Indian Institute of Technology Guwahati
Advances in Protein Chemistry and Structural Biology | Year: 2011

Ever since lysozyme was discovered by Fleming in 1922, this protein has emerged as a model for investigations on protein structure and function. Over the years, several high-resolution structures have yielded a wealth of structural data on this protein. Extensive studies on folding of lysozyme have shown how different regions of this protein dynamically interact with one another. Data is also available from numerous biotechnological studies wherein lysozyme has been employed as a model protein for recovering active recombinant protein from inclusion bodies using small molecules like l-arginine. A variety of conditions have been developed in vitro to induce fibrillation in hen lysozyme. They include (a) acidic pH at elevated temperature, (b) concentrated solutions of ethanol, (c) moderate concentrations of guanidinium hydrochloride at moderate temperature, and (d) alkaline pH at room temperature. This review aims to bring together similarities and differences in aggregation mechanisms, morphology of aggregates, and related issues that arise using the different conditions mentioned above to improve our understanding. The alkaline pH condition (pH 12.2), discovered and studied extensively in our lab, shall receive special attention. More than a decade ago, it was revealed that mutations in human lysozyme can cause accumulation of large quantities of amyloid in liver, kidney, and other regions of gastrointestinal tract. Understanding the mechanism of lysozyme aggregation will probably have therapeutic implications for the treatment of systemic nonneuropathic amyloidosis. Numerous studies have begun to focus attention on inhibition of lysozyme aggregation using antibody or small molecules. The enzymatic activity of lysozyme presents a convenient handle to quantify the native population of lysozyme in a sample where aggregation has been inhibited. The rich information available on lysozyme coupled with the multiple conditions that have been successful in inducing/inhibiting its aggregation in vitro makes lysozyme an ideal model protein to investigate amyloidogenesis. © 2011 Elsevier Inc. All rights reserved.

Narayanan R.L.,Max Planck Institute for Biophysical Chemistry | Durr U.H.N.,Max Planck Institute for Biophysical Chemistry | Bibow S.,Max Planck Institute for Biophysical Chemistry | Biernat J.,Max Planck Unit for Structural Molecular Biology | And 3 more authors.
Journal of the American Chemical Society | Year: 2010

Intrinsically disordered proteins carry out many important functions in the cell. However, the lack of an ordered structure causes dramatic signal overlap and complicates the NMR-based characterization of their structure and dynamics. Here we demonstrate that the resonance assignment of 441-residue Tau and its smaller isoforms, htau24 (383 residues) and htau23 (352 residues), three prototypes of intrinsically disordered proteins, which bind to microtubules and play a key role in Alzheimer disease, can be obtained within 5 days by a combination of seven-dimensional NMR spectra with optimized methods for automatic assignment. Chemical shift differences between the three isoforms provide evidence for the global folding of Tau in solution. © 2010 American Chemical Society.

Wang Y.,Max Planck Unit for Structural Molecular Biology | Martinez-Vicente M.,Yeshiva University | Kruger U.,Max Planck Unit for Structural Molecular Biology | Kaushik S.,Yeshiva University | And 4 more authors.
Autophagy | Year: 2010

Tau aggregation characterizes a series of neurodegenerative diseases including AD and other tauopathies. The distribution of Tau deposits correlates with the loss of neurons in these neurodegenerative diseases, and Tauinduced toxicity depends on its ability to aggregate. We have used an inducible cell model to study the expression of Tau variants, the buildup of aggregates, and their removal by the autophagy-lysosomal system. Incomplete chaperone-mediated autophagy of Tau generates amyloidogenic fragments that promote aggregation. The Tau aggregates are removed from cells by macroautophagy. Thus the two autophagic pathways could become possible therapeutic targets. © 2010 Landes Bioscience.

Wang Y.,Max Planck Unit for Structural Molecular Biology | Kruger U.,Max Planck Unit for Structural Molecular Biology | Mandelkow E.,Max Planck Unit for Structural Molecular Biology | Mandelkow E.-M.,Max Planck Unit for Structural Molecular Biology
Neurodegenerative Diseases | Year: 2010

We have studied the mechanism of aggregation in an inducible cell model of Tau pathology. When the repeat domain of human Tau (TauRD) carrying the FTDP-17 mutation ΔK280 is expressed, the cells develop aggregates, as seen by thioflavin S fluorescence, electron microscopy, and sarkosyl extraction methods. By contrast, mutants of TauRD that are unable to generate β-structure do not aggregate. Enhanced aggregation leads to enhanced toxicity, visible by live cell microscopy and LDH release assay. The aggregation process is initiated by the sequential cleavage of TauRD which yields highly amyloidogenic fragments. This cleavage occurs only with proaggregant TauRD, and not with the nonaggregating mutants, indicating that β-structure makes TauRD vulnerable to both proteolytic degradation and aggregation. Aggregation is reversed by switching off the expression of TauRD, by inhibitor compounds, and by certain protease inhibitors. In all cases, the enhanced toxicity is rescued. The clearance of the aggregates involves autophagy, whereas proteasomal degradation plays only a minor role. Copyright © 2010 S. Karger AG, Basel.

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