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Small-molecule allosteric inhibitors of BAX

Abstract

BAX is a critical effector of the mitochondrial cell death pathway in response to a diverse range of stimuli in physiological and disease contexts. Upon binding by BH3-only proteins, cytosolic BAX undergoes conformational activation and translocation, resulting in mitochondrial outer-membrane permeabilization. Efforts to rationally target BAX and develop inhibitors have been elusive, despite the clear therapeutic potential of inhibiting BAX-mediated cell death in a host of diseases. Here, we describe a class of small-molecule BAX inhibitors, termed BAIs, that bind directly to a previously unrecognized pocket and allosterically inhibit BAX activation. BAI binding around the hydrophobic helix α5 using hydrophobic and hydrogen bonding interactions stabilizes key areas of the hydrophobic core. BAIs inhibit conformational events in BAX activation that prevent BAX mitochondrial translocation and oligomerization. Our data highlight a novel paradigm for effective and selective pharmacological targeting of BAX to enable rational development of inhibitors of BAX-mediated cell death.

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Data generated or analyzed during the study and included in this published article are available from the corresponding author on reasonable request.

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Acknowledgements

We thank B. Agianian and A. Haimowitz for assistance with MST controls and BAX C62S/C126S/S3C mutant preparation. Studies were supported by an American Heart Association Collaborative Science Award (15CSA26240000) to E.G. and R.N.K. Support was also provided by NIH award 1R01CA178394 to E.G. and the Fondation Leducq Transatlantic Network of Excellence grant (RA15CVD04) to E.G. and R.N.K. E.G. is supported by the Pershing Square Sohn Cancer Research Alliance and the Irma T. Hirschl Trust Career Award. NMR data were collected with support from NIH awards 1S10OD016305, P30 CA013330 a grant from NYSTAR.

Author information

T.P.G. performed NMR, biochemical and molecular modeling studies. D.E.R. performed cell-based studies, and S.L. performed mass spectrometry studies. D.A. and R.N.K. performed cell-based studies. E.G. conceived the study, designed experiments and wrote the manuscript, which was edited by all authors.

Competing interests

E.G., R.N.K., T.P.G, and D.A. are inventors on a patent application PCT/US2018/021644 submitted by Albert Einstein College of Medicine that covers compounds, compositions and methods for BAX inhibition for the treatment of diseases and disorders.

Correspondence to Evripidis Gavathiotis.

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Further reading

Fig. 1: BAI1 and BAI2 bind directly to BAX and inhibit BAX activation.
Fig. 2: BAI1 binds to inactive BAX at a novel allosteric site.
Fig. 3: BAI1 allosterically inhibits BIM BH3-mediated BAX activation and oligomerization.
Fig. 4: Structural and biochemical mechanism of BAI1-mediated BAX inhibition.
Fig. 5: BAI1 inhibits cell death in BAX-dependent manner.