Limits...
Identification of Small Molecule Inhibitors of Tau Aggregation by Targeting Monomeric Tau As a Potential Therapeutic Approach for Tauopathies

View Article: PubMed Central

ABSTRACT

A potential strategy to alleviate the aggregation of intrinsically disordered proteins (IDPs) is to maintain the native functional state of the protein by small molecule binding. However, the targeting of the native state of IDPs by small molecules has been challenging due to their heterogeneous conformational ensembles. To tackle this challenge, we applied a high-throughput chemical microarray surface plasmon resonance imaging screen to detect the binding between small molecules and monomeric full-length Tau, a protein linked with the onset of a range of Tauopathies. The screen identified a novel set of drug-like fragment and lead-like compounds that bound to Tau. We verified that the majority of these hit compounds reduced the aggregation of different Tau constructs in vitro and in N2a cells. These results demonstrate that Tau is a viable receptor of drug-like small molecules. The drug discovery approach that we present can be applied to other IDPs linked to other misfolding diseases such as Alzheimer’s and Parkinson’s diseases.

No MeSH data available.


Graphical representation of the effect of hit compounds on the aggregation of different Tau constructs in vitro and in N2a cells. No significant correlation was observed in the ability of hit compounds to reduce aggregation of the different Tau constructs (A) in vitro and (B) Tau4RDDK280 in N2a cells. Nevertheless, several hit compounds had significant aggregation inhibition effect in both cellular and the in vitro aggregation assays.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4997948&req=5

Figure 4: Graphical representation of the effect of hit compounds on the aggregation of different Tau constructs in vitro and in N2a cells. No significant correlation was observed in the ability of hit compounds to reduce aggregation of the different Tau constructs (A) in vitro and (B) Tau4RDDK280 in N2a cells. Nevertheless, several hit compounds had significant aggregation inhibition effect in both cellular and the in vitro aggregation assays.

Mentions: In N2a cells, the hit compounds, in general, had a more extensive ability to reduce fibril formation of Tau4RDDK280, compared to in vitro experiments. One reason for this may be the fact that there is less Tau4RDDK280 in the cells and thus less amount of compound is needed to have a functional effect. No significant correlation in the ability of hit compounds to reduce aggregation of Tau4RDDK280 in N2a cells compared to in vitro was observed, however, several hit compounds had significant aggregation inhibition effect in both cellular and the in vitro assay (Table 4 and Fig. 4). We further confirmed our findings by demonstrating that the three selected compounds (Table 4) reduced the aggregation of Tau4RDDK280 in Na2 cells in a dose dependent manner. These hit compounds are likely to act via single compound monomer species, because DLS experiments did not detect self-aggregated compound species at the assayed conditions. The concentration of the compound that can modulate aggregation is likely to depend on the relative ratio of protein and compound, therefore, the necessary compound concentration for in vivo aggregation modulation is determined by the absolute level of soluble monomeric Tau in neurons, which may be as low as 20 nM [22]. The functional effect of our compounds in reducing Tau aggregation is comparable to other reported optimized aggregation inhibitors. For example, the rhodanine based inhibitor bb14 [40] was less than 2 times more potent in reducing Tau4RDDK280 aggregation in vitro compared to our best hits, while the phenylthiazolyl-hydrazide based inhibitor BSc3094 [41] was about 2-3 more effective in reducing aggregation in N2a cells compared to our best hits. Independently of their inhibitory capacity, the reported hit compounds (Fig. 3 and Table 4) are promising starting points for hit optimization efforts, because these compound have no reactive fragments and generally have drug-like physicochemical properties.


Identification of Small Molecule Inhibitors of Tau Aggregation by Targeting Monomeric Tau As a Potential Therapeutic Approach for Tauopathies
Graphical representation of the effect of hit compounds on the aggregation of different Tau constructs in vitro and in N2a cells. No significant correlation was observed in the ability of hit compounds to reduce aggregation of the different Tau constructs (A) in vitro and (B) Tau4RDDK280 in N2a cells. Nevertheless, several hit compounds had significant aggregation inhibition effect in both cellular and the in vitro aggregation assays.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4997948&req=5

Figure 4: Graphical representation of the effect of hit compounds on the aggregation of different Tau constructs in vitro and in N2a cells. No significant correlation was observed in the ability of hit compounds to reduce aggregation of the different Tau constructs (A) in vitro and (B) Tau4RDDK280 in N2a cells. Nevertheless, several hit compounds had significant aggregation inhibition effect in both cellular and the in vitro aggregation assays.
Mentions: In N2a cells, the hit compounds, in general, had a more extensive ability to reduce fibril formation of Tau4RDDK280, compared to in vitro experiments. One reason for this may be the fact that there is less Tau4RDDK280 in the cells and thus less amount of compound is needed to have a functional effect. No significant correlation in the ability of hit compounds to reduce aggregation of Tau4RDDK280 in N2a cells compared to in vitro was observed, however, several hit compounds had significant aggregation inhibition effect in both cellular and the in vitro assay (Table 4 and Fig. 4). We further confirmed our findings by demonstrating that the three selected compounds (Table 4) reduced the aggregation of Tau4RDDK280 in Na2 cells in a dose dependent manner. These hit compounds are likely to act via single compound monomer species, because DLS experiments did not detect self-aggregated compound species at the assayed conditions. The concentration of the compound that can modulate aggregation is likely to depend on the relative ratio of protein and compound, therefore, the necessary compound concentration for in vivo aggregation modulation is determined by the absolute level of soluble monomeric Tau in neurons, which may be as low as 20 nM [22]. The functional effect of our compounds in reducing Tau aggregation is comparable to other reported optimized aggregation inhibitors. For example, the rhodanine based inhibitor bb14 [40] was less than 2 times more potent in reducing Tau4RDDK280 aggregation in vitro compared to our best hits, while the phenylthiazolyl-hydrazide based inhibitor BSc3094 [41] was about 2-3 more effective in reducing aggregation in N2a cells compared to our best hits. Independently of their inhibitory capacity, the reported hit compounds (Fig. 3 and Table 4) are promising starting points for hit optimization efforts, because these compound have no reactive fragments and generally have drug-like physicochemical properties.

View Article: PubMed Central

ABSTRACT

A potential strategy to alleviate the aggregation of intrinsically disordered proteins (IDPs) is to maintain the native functional state of the protein by small molecule binding. However, the targeting of the native state of IDPs by small molecules has been challenging due to their heterogeneous conformational ensembles. To tackle this challenge, we applied a high-throughput chemical microarray surface plasmon resonance imaging screen to detect the binding between small molecules and monomeric full-length Tau, a protein linked with the onset of a range of Tauopathies. The screen identified a novel set of drug-like fragment and lead-like compounds that bound to Tau. We verified that the majority of these hit compounds reduced the aggregation of different Tau constructs in vitro and in N2a cells. These results demonstrate that Tau is a viable receptor of drug-like small molecules. The drug discovery approach that we present can be applied to other IDPs linked to other misfolding diseases such as Alzheimer’s and Parkinson’s diseases.

No MeSH data available.