Hsp40s display class-specific binding profiles, serving complementary roles in the prevention of tau amyloid formation

The microtubule-associated protein, tau, is the major subunit of neurofibrillary tangles, forming insoluble, amyloid-type aggregates associated with neurodegenerative conditions, such as Alzheimer's disease. Tau aggregation, however, can be prevented in the cell by a class of proteins known as molecular chaperones, which play important roles in maintaining protein homeostasis. While numerous chaperones are known to interact with tau, though, little is known about the detailed mechanisms by which these prevent tau aggregation. Here, we describe the effects of the ATP-independent Hsp40 chaperones, DNAJA2 and DNAJB1, on tau amyloid fiber formation and compare these to the well-studied small heat shock protein HSPB1. We find that each chaperone prevents tau aggregation differently, by interacting with distinct sets of tau species along the aggregation pathway and thereby affecting their incorporation into fibers. Whereas HSPB1 only binds tau monomers, DNAJB1 and DNAJA2 recognize aggregation-prone tau conformers and even mature fibers, thus efficiently preventing formation of tau amyloids. In addition, we find that both Hsp40s bind tau seeds and fibers via their C-terminal domain II (CTDII), with DNAJA2 being further capable of recognizing tau monomers by a second, different site in CTDI. These results provide important insight into the molecular mechanism by which the different members of the Hsp40 chaperone family counteract the formation, propagation, and toxicity of tau aggregates. Furthermore, our findings highlight the fact that chaperones from different families and different classes play distinct, but complementary roles in preventing pathological protein aggregation.

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Hsp40s play complementary roles in the prevention of tau amyloid formation

eLife ◽

10.7554/elife.69601 ◽

2021 ◽

Vol 10 ◽

Author(s):

Rose Irwin ◽

Ofrah Faust ◽

Ivana Petrovic ◽

Sharon Grayer Wolf ◽

Hagen Hofmann ◽

...

Keyword(s):

Heat Shock ◽

Heat Shock Protein ◽

Molecular Chaperones ◽

Small Heat Shock Protein ◽

Fiber Formation ◽

Amyloid Formation ◽

Protein Tau ◽

Distinct Site ◽

Amyloid Fiber Formation ◽

Tau Aggregation

The microtubule-associated protein, tau, is the major subunit of neurofibrillary tangles associated with neurodegenerative conditions, such as Alzheimer's disease. In the cell, however, tau aggregation can be prevented by a class of proteins known as molecular chaperones. While numerous chaperones are known to interact with tau, though, little is known regarding the mechanisms by which these prevent tau aggregation. Here, we describe the effects of ATP-independent Hsp40 chaperones, DNAJA2 and DNAJB1, on tau amyloid-fiber formation, and compare these to the small heat-shock protein HSPB1. We find that the chaperones play complementary roles, with each preventing tau aggregation differently and interacting with distinct sets of tau species. Whereas HSPB1 only binds tau monomers, DNAJB1 and DNAJA2 recognize aggregation-prone conformers and even mature fibers. In addition, we find that both Hsp40s bind tau seeds and fibers via their C-terminal domain II (CTDII), with DNAJA2 being further capable of recognizing tau monomers by a second, distinct site in CTDI. These results lay out the mechanisms by which the diverse members of the Hsp40 family counteract the formation and propagation of toxic tau aggregates, and highlight the fact that chaperones from different families/classes play distinct, yet complementary roles in preventing pathological protein aggregation.

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Hsp70 molecular chaperones: multifunctional allosteric holding and unfolding machines

Biochemical Journal ◽

10.1042/bcj20170380 ◽

2019 ◽

Vol 476 (11) ◽

pp. 1653-1677 ◽

Cited By ~ 19

Author(s):

Eugenia M. Clerico ◽

Wenli Meng ◽

Alexandra Pozhidaeva ◽

Karishma Bhasne ◽

Constantine Petridis ◽

...

Keyword(s):

Molecular Chaperones ◽

Protein Homeostasis ◽

Nucleotide Exchange ◽

Cellular Functions ◽

The Past ◽

Hsp70 Family ◽

Nucleotide Exchange Factors ◽

Client Proteins ◽

Structural Insights ◽

Insight Into

AbstractThe Hsp70 family of chaperones works with its co-chaperones, the nucleotide exchange factors and J-domain proteins, to facilitate a multitude of cellular functions. Central players in protein homeostasis, these jacks-of-many-trades are utilized in a variety of ways because of their ability to bind with selective promiscuity to regions of their client proteins that are exposed when the client is unfolded, either fully or partially, or visits a conformational state that exposes the binding region in a regulated manner. The key to Hsp70 functions is that their substrate binding is transient and allosterically cycles in a nucleotide-dependent fashion between high- and low-affinity states. In the past few years, structural insights into the molecular mechanism of this allosterically regulated binding have emerged and provided deep insight into the deceptively simple Hsp70 molecular machine that is so widely harnessed by nature for diverse cellular functions. In this review, these structural insights are discussed to give a picture of the current understanding of how Hsp70 chaperones work.

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DnaJC7 binds natively folded structural elements in tau to inhibit amyloid formation

10.1101/2020.12.15.422895 ◽

2020 ◽

Author(s):

Zhiqiang Hou ◽

Pawel M Wydorski ◽

Valerie A Perez ◽

Ayde Mendoza-Oliva ◽

Bryan D Ryder ◽

...

Keyword(s):

Molecular Chaperones ◽

Therapeutic Intervention ◽

Amyloid Formation ◽

Structural Elements ◽

Wild Type ◽

Beta Turn ◽

Chaperone Binding ◽

Tau Aggregation ◽

Tpr Domain

Molecular chaperones, including Hsp70/Hsp40 families, play central roles in binding substrates to prevent their aggregation. How Hsp40s select different conformations of substrates remains poorly understood. Here, we report a novel interaction between the Hsp40 DnaJC7 and tau that efficiently suppresses tau aggregation in vitro and in cells. DnaJC7 binds preferentially to natively folded wild-type tau, but disease-associated mutants in tau reduce chaperone binding affinity. We identify that DnaJC7 uses a single TPR domain to recognize a beta-turn element in tau that contains the 275VQIINK280 amyloid motif. Wild-type tau beta-turn fragments, but not mutant fragments, can block full-length tau binding to DnaJC7. These data suggest DnaJC7 preferentially binds and stabilizes natively folded conformations of tau to prevent tau conversion into amyloids. This identifies a novel mechanism of tau aggregation regulation that can be exploited as both a diagnostic and a therapeutic intervention.

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Human chaperones untangle fibrils of the Alzheimer protein Tau

10.1101/426650 ◽

2018 ◽

Cited By ~ 4

Author(s):

Luca Ferrari ◽

Willie J.C. Geerts ◽

Marloes van Wezel ◽

Renate Kos ◽

Aikaterini Konstantoulea ◽

...

Keyword(s):

Molecular Chaperones ◽

Neurodegenerative Disorder ◽

Protein Homeostasis ◽

Human Homologue ◽

Protein Tau ◽

End Products ◽

Hsp70 Chaperone ◽

Novel Drug ◽

Human Hsp70 ◽

Tau Fibrils

AbstractAlzheimer’s Disease is the most common neurodegenerative disorder. A hallmark of this disease is aggregation of the protein Tau into fibrillar tangles, which is ultimately linked to neuronal death 1,2. Oligomeric precursors of Tau fibrils are suspected to be the neurotoxic agent while fibrils themselves may be less harmful end products of the aggregation process 3,4. Evolutionary conserved families of molecular chaperones maintain protein homeostasis in healthy cells, preventing aggregation 5,6. Here, we investigate whether such chaperones could possibly reverse the aggregation reaction and dissolve Tau fibrils. Indeed we find that the human Hsp70 chaperone system disaggregates Tau fibrils. Both the bacterial and human Hsp70 chaperone systems disassemble fibril superstructures assembled of several fibril strands into single fibrils, indicating that this is an evolutionary conserved capacity of the Hsp70 system. However, further disaggregation of Tau fibrils into oligomers and even monomers is reserved to the human homologue. Thus, although bacteria possess an effective machinery to dissolve amorphous aggregates 7-9, we see that they do not have the means to disaggregate fibrils. Fibrillar aggregates, therefore, require different chaperone systems than amorphous aggregates, and this is a property acquired by Hsp70 during evolution. This makes the Hsp70 system an interesting target for novel drug strategies in Alzheimer.

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DnaJC7 binds natively folded structural elements in tau to inhibit amyloid formation

10.21203/rs.3.rs-129204/v1 ◽

2021 ◽

Author(s):

Lukasz Joachimiak ◽

Zhiqiang Hou ◽

Pawel Wydorski ◽

Valerie Perez ◽

Ayde Mendoza-Oliva ◽

...

Keyword(s):

Binding Affinity ◽

Molecular Chaperones ◽

Therapeutic Intervention ◽

Amyloid Formation ◽

Structural Elements ◽

Wild Type ◽

Chaperone Binding ◽

Tau Aggregation ◽

Tpr Domain

Abstract Molecular chaperones, including Hsp70/Hsp40 families, play central roles in binding substrates to prevent their aggregation. How Hsp40s select different conformations of substrates remains poorly understood. Here, we report a novel interaction between the Hsp40 DnaJC7 and tau that efficiently suppresses tau aggregation in vitro and in cells. DnaJC7 binds preferentially to natively folded wild-type tau, but disease-associated mutants in tau reduce chaperone binding affinity. We identify that DnaJC7 uses a single TPR domain to recognize a β-turn element in tau that contains the 275VQIINK280 amyloid motif. Wild-type tau β-turn fragments, but not mutant fragments, can block full-length tau binding to DnaJC7. These data suggest DnaJC7 preferentially binds and stabilizes natively folded conformations of tau to prevent tau conversion into amyloids. This identifies a novel mechanism of tau aggregation regulation that can be exploited as both a diagnostic and a therapeutic intervention.

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The physical chemistry of the amyloid phenomenon: thermodynamics and kinetics of filamentous protein aggregation

Essays in Biochemistry ◽

10.1042/bse0560011 ◽

2014 ◽

Vol 56 ◽

pp. 11-39 ◽

Cited By ~ 31

Author(s):

Alexander K. Buell ◽

Christopher M. Dobson ◽

Tuomas P.J. Knowles

Keyword(s):

Protein Aggregation ◽

Molecular Chaperones ◽

Amyloid Fibrils ◽

Theoretical Modelling ◽

Amyloid Formation ◽

Recent Developments ◽

The Individual ◽

Kinetics Of ◽

Soluble State ◽

Insight Into

In this chapter, we present an overview of the kinetics and thermodynamics of protein aggregation into amyloid fibrils. The perspective we adopt is largely experimental, but we also discuss recent developments in data analysis and we show that only a combination of well-designed experiments with appropriate theoretical modelling is able to provide detailed mechanistic insight into the complex pathways of amyloid formation. In the first part of the chapter, we describe measurements of the thermodynamic stability of the amyloid state with respect to the soluble state of proteins, as well as the magnitude and origin of this stability. In the second part, we discuss in detail the kinetics of the individual molecular steps in the overall mechanism of the conversion of soluble protein into amyloid fibrils. Finally, we highlight the effects of external factors, such as salt type and concentration, chemical denaturants and molecular chaperones on the kinetics of aggregation.

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DNAJB chaperones suppress destabilised protein aggregation via a region unique from that used to inhibit amyloidogenesis

Journal of Cell Science ◽

10.1242/jcs.255596 ◽

2021 ◽

pp. jcs.255596

Author(s):

Shannon McMahon ◽

Steven Bergink ◽

Harm H. Kampinga ◽

Heath Ecroyd

Keyword(s):

Protein Aggregation ◽

Molecular Chaperones ◽

Neurodegenerative Disorders ◽

Firefly Luciferase ◽

Amyloid Formation ◽

Protein Homeostasis ◽

Formation Processes ◽

Related Protein ◽

Inclusion Formation ◽

In Cells

Disturbances to protein homeostasis (proteostasis) can lead to protein aggregation and inclusion formation, processes associated with a variety of neurodegenerative disorders. DNAJBs are molecular chaperones which have been identified as potent suppressors of disease-related protein aggregation. In this work, a destabilised isoform of firefly luciferase (R188Q/R261Q Fluc; FlucDM) was overexpressed in cells to assess the capacity of DNAJBs to inhibit inclusion formation. Co-expression of all DNAJBs tested significantly inhibited the intracellular aggregation of FlucDM. Moreover, we show that DNAJBs suppress aggregation by supporting the Hsp70-dependent degradation of FlucDM via the proteasome. The serine-rich stretch in DNAJB6 and DNAJB8, essential for preventing fibrillar aggregation, is not involved in the suppression of FlucDM inclusion formation. Conversely, deletion of the C-terminal TTK-LKS motif in DNAJB6 and DNAJB8, a region not required to suppress polyQ aggregation, abolished its ability to inhibit inclusion formation by FlucDM. Thus, our data suggest that DNAJB6 and DNAJB8 possess two distinct regions for binding substrates, one that is responsible for binding β-hairpins that form during amyloid formation and another that interacts with exposed hydrophobic patches in aggregation-prone clients.

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DNAJB chaperones inhibit aggregation of destabilised proteins via a C-terminal region distinct from that used to prevent amyloid formation

10.1101/2020.10.08.326280 ◽

2020 ◽

Author(s):

Shannon McMahon ◽

Steven Bergink ◽

Harm H. Kampinga ◽

Heath Ecroyd

Keyword(s):

Protein Aggregation ◽

Molecular Chaperones ◽

Firefly Luciferase ◽

Amyloid Formation ◽

Protein Homeostasis ◽

Formation Processes ◽

Inclusion Formation ◽

Different Types ◽

Summary Statement ◽

Client Proteins

AbstractDisturbances to protein homeostasis (proteostasis) can lead to protein aggregation and inclusion formation, processes associated with a variety of neurodegenerative disorders. DNAJBs are molecular chaperones previously identified as potent suppressors of disease-related protein aggregation. In this work, we over-expressed a destabilised isoform of firefly luciferase (R188Q/R261Q Fluc; FlucDM) in cells to assess the capacity of DNAJBs to inhibit inclusion formation. Co-expression of all DNAJBs tested significantly inhibited the intracellular aggregation of FlucDM. Moreover, we show that DNAJBs suppress aggregation by supporting the Hsp70-dependent degradation of FlucDM via the proteasome. The serine-rich stretch in DNAJB6 and DNAJB8, essential for preventing fibrillar aggregation, is not involved in the suppression of FlucDM inclusion formation. Conversely, deletion of the C-terminal TTK-LKS region in DNAJB8, a region not required to suppress polyQ aggregation, abolished its ability to inhibit inclusion formation by FlucDM. Thus, our data suggest that DNAJB6 and DNAJB8 possess two distinct domains involved in the inhibition of protein aggregation, one responsible for binding to β-hairpins that form during amyloid formation and another that mediates the degradation of destabilised client proteins via the proteasome.Summary statementSpecialised DNAJB molecular chaperones are potent suppressors of protein aggregation and interact with different types of client proteins via distinct C-terminal regions

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DnaJC7 binds natively folded structural elements in tau to inhibit amyloid formation

Nature Communications ◽

10.1038/s41467-021-25635-y ◽

2021 ◽

Vol 12 (1) ◽

Author(s):

Zhiqiang Hou ◽

Pawel M. Wydorski ◽

Valerie A. Perez ◽

Aydé Mendoza-Oliva ◽

Bryan D. Ryder ◽

...

Keyword(s):

Molecular Chaperones ◽

Amyloid Formation ◽

Structural Elements ◽

Wild Type ◽

Structural Element ◽

Chaperone Binding ◽

J Domain ◽

Tau Aggregation ◽

Tpr Domain

AbstractMolecular chaperones, including Hsp70/J-domain protein (JDP) families, play central roles in binding substrates to prevent their aggregation. How JDPs select different conformations of substrates remains poorly understood. Here, we report an interaction between the JDP DnaJC7 and tau that efficiently suppresses tau aggregation in vitro and in cells. DnaJC7 binds preferentially to natively folded wild-type tau, but disease-associated mutants in tau reduce chaperone binding affinity. We identify that DnaJC7 uses a single TPR domain to recognize a β-turn structural element in tau that contains the 275VQIINK280 amyloid motif. Wild-type tau, but not mutant, β-turn structural elements can block full-length tau binding to DnaJC7. These data suggest DnaJC7 preferentially binds and stabilizes natively folded conformations of tau to prevent tau conversion into amyloids. Our work identifies a novel mechanism of tau aggregation regulation that can be exploited as both a diagnostic and a therapeutic intervention.

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