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Docking of competitive inhibitors to the P2X7 receptor family reveals key differences responsible for changes in response between rat and human.

Caseley EA, Muench SP, Baldwin SA, Simmons K, Fishwick CW, Jiang LH - Bioorg. Med. Chem. Lett. (2015)

Bottom Line: Importantly this residue is replaced by Leu in the rat P2X7 receptor resulting in a significantly reduced binding affinity.This work provides new insights into binding of P2X7 inhibitors and shows the structural difference in human and rat P2X7 receptors which results in a difference in affinity.Such information is useful both for the rational design of inhibitors based on these scaffolds and also the way in which these compounds are tested in animal models.

View Article: PubMed Central - PubMed

Affiliation: School of Biomedical Sciences, University of Leeds, Leeds, UK. Electronic address: bs09e2c@leeds.ac.uk.

No MeSH data available.


Related in: MedlinePlus

Docking of SB203580, AZ11645373 and KN62 into the human (A, C and E) and rat (B, D and F) P2X7 receptors, respectively. Residues Phe95 and Leu95 as well as docked inhibitors are depicted in stick format. Residues labelled as A and B are from different subunits of the same receptor.
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f0010: Docking of SB203580, AZ11645373 and KN62 into the human (A, C and E) and rat (B, D and F) P2X7 receptors, respectively. Residues Phe95 and Leu95 as well as docked inhibitors are depicted in stick format. Residues labelled as A and B are from different subunits of the same receptor.

Mentions: Of these important residues in the binding site, Phe95 appears to have a key role in determining the orientation of each compound. This residue is predicted to form pi-stacking interactions with aromatic rings within the structures of the three antagonists (Fig. 2A, C and E). Interestingly, previous studies have identified Phe95 as determining the species-specific activity of some P2X7-specific antagonists.34,35 This previous work investigated the mechanism of action of species-specific P2X7 inhibitors. The first of these studies found that mutating Phe95 in the human receptor to the Leu found in the rat greatly reduced the inhibitory activity of KN62 and SB203580,34 whereas the second found that this was also the case with AZ11645373.35 The three antagonists docked in this study all display species-specific activity to varying degrees. SB203580 acts as a low-affinity, non-competitive inhibitor of the human receptor, with an IC50 of approximately 5 μM, but does not act at the rat receptor.36 KN62 inhibits the human receptor with an IC50 of ∼100 nM but similarly does not act on the rat37 receptor. AZ11645373 inhibits human P2X7 with an IC50 of ∼90 nM whereas this compound is over 500-fold less effective at inhibiting the rat receptor and results in less than 50% inhibition at concentrations of 10 μM.38 In the rat P2X7 receptor the equivalent residue to Phe95 is a leucine, which due to its lack of aromatic side chain will lose the stacking interaction of these compounds with the receptor. As such we carried out docking with these molecules in the rat receptor to accompany the experiments in the human P2X7 receptor. The results were strikingly different to those seen in the human counterpart; with significantly lower predicted binding affinities (in the millimolar range for the rat receptor compared to nano- or micromolar range for human) as well as notably different predicted binding positions within this site although agonist efficacy may also play a role.


Docking of competitive inhibitors to the P2X7 receptor family reveals key differences responsible for changes in response between rat and human.

Caseley EA, Muench SP, Baldwin SA, Simmons K, Fishwick CW, Jiang LH - Bioorg. Med. Chem. Lett. (2015)

Docking of SB203580, AZ11645373 and KN62 into the human (A, C and E) and rat (B, D and F) P2X7 receptors, respectively. Residues Phe95 and Leu95 as well as docked inhibitors are depicted in stick format. Residues labelled as A and B are from different subunits of the same receptor.
© Copyright Policy - CC BY
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4508345&req=5

f0010: Docking of SB203580, AZ11645373 and KN62 into the human (A, C and E) and rat (B, D and F) P2X7 receptors, respectively. Residues Phe95 and Leu95 as well as docked inhibitors are depicted in stick format. Residues labelled as A and B are from different subunits of the same receptor.
Mentions: Of these important residues in the binding site, Phe95 appears to have a key role in determining the orientation of each compound. This residue is predicted to form pi-stacking interactions with aromatic rings within the structures of the three antagonists (Fig. 2A, C and E). Interestingly, previous studies have identified Phe95 as determining the species-specific activity of some P2X7-specific antagonists.34,35 This previous work investigated the mechanism of action of species-specific P2X7 inhibitors. The first of these studies found that mutating Phe95 in the human receptor to the Leu found in the rat greatly reduced the inhibitory activity of KN62 and SB203580,34 whereas the second found that this was also the case with AZ11645373.35 The three antagonists docked in this study all display species-specific activity to varying degrees. SB203580 acts as a low-affinity, non-competitive inhibitor of the human receptor, with an IC50 of approximately 5 μM, but does not act at the rat receptor.36 KN62 inhibits the human receptor with an IC50 of ∼100 nM but similarly does not act on the rat37 receptor. AZ11645373 inhibits human P2X7 with an IC50 of ∼90 nM whereas this compound is over 500-fold less effective at inhibiting the rat receptor and results in less than 50% inhibition at concentrations of 10 μM.38 In the rat P2X7 receptor the equivalent residue to Phe95 is a leucine, which due to its lack of aromatic side chain will lose the stacking interaction of these compounds with the receptor. As such we carried out docking with these molecules in the rat receptor to accompany the experiments in the human P2X7 receptor. The results were strikingly different to those seen in the human counterpart; with significantly lower predicted binding affinities (in the millimolar range for the rat receptor compared to nano- or micromolar range for human) as well as notably different predicted binding positions within this site although agonist efficacy may also play a role.

Bottom Line: Importantly this residue is replaced by Leu in the rat P2X7 receptor resulting in a significantly reduced binding affinity.This work provides new insights into binding of P2X7 inhibitors and shows the structural difference in human and rat P2X7 receptors which results in a difference in affinity.Such information is useful both for the rational design of inhibitors based on these scaffolds and also the way in which these compounds are tested in animal models.

View Article: PubMed Central - PubMed

Affiliation: School of Biomedical Sciences, University of Leeds, Leeds, UK. Electronic address: bs09e2c@leeds.ac.uk.

No MeSH data available.


Related in: MedlinePlus