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An interconnected hierarchical model of cell death regulation by the BCL-2 family

Nature Cell Biology volume 17, pages 12701281 (2015) | Download Citation

Abstract

Multidomain pro-apoptotic BAX and BAK, once activated, permeabilize mitochondria to trigger apoptosis, whereas anti-apoptotic BCL-2 members preserve mitochondrial integrity. The BH3-only molecules (BH3s) promote apoptosis by either activating BAX–BAK or inactivating anti-apoptotic members. Here, we present biochemical and genetic evidence that NOXA is a bona fide activator BH3. Using combinatorial gain-of-function and loss-of-function approaches in Bid−/−Bim−/−Puma−/−Noxa−/− and Bax−/−Bak−/− cells, we have constructed an interconnected hierarchical model that accommodates and explains how the intricate interplays between the BCL-2 members dictate cellular survival versus death. BID, BIM, PUMA and NOXA directly induce stepwise, bimodal activation of BAX–BAK. BCL-2, BCL-XL and MCL-1 inhibit both modes of BAX–BAK activation by sequestering activator BH3s and ‘BH3-exposed’ monomers of BAX–BAK, respectively. Furthermore, autoactivation of BAX and BAK can occur independently of activator BH3s through downregulation of BCL-2, BCL-XL and MCL-1. Our studies lay a foundation for targeting the BCL-2 family for treating diseases with dysregulated apoptosis.

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References

  1. 1.

    , & BCL-2 family members and the mitochondria in apoptosis. Genes Dev. 13, 1899–1911 (1999).

  2. 2.

    & The BCL-2 protein family: opposing activities that mediate cell death. Nat. Rev. Mol. Cell Biol. 9, 47–59 (2008).

  3. 3.

    , , & Control of apoptosis by the BCL-2 protein family: implications for physiology and therapy. Nat. Rev. Mol. Cell Biol. 15, 49–63 (2014).

  4. 4.

    The expanding role of mitochondria in apoptosis. Genes Dev. 15, 2922–2933 (2001).

  5. 5.

    & Mitochondria: releasing power for life and unleashing the machineries of death. Cell 112, 481–490 (2003).

  6. 6.

    et al. Hierarchical regulation of mitochondrion-dependent apoptosis by BCL-2 subfamilies. Nat. Cell Biol. 8, 1348–1358 (2006).

  7. 7.

    , & Building blocks of the apoptotic pore: how Bax and Bak are activated and oligomerize during apoptosis. Cell Death Differ. 21, 196–205 (2014).

  8. 8.

    et al. tBID, a membrane-targeted death ligand, oligomerizes BAK to release cytochrome c. Genes Dev. 14, 2060–2071 (2000).

  9. 9.

    et al. BCL-2, BCL-XL sequester BH3 domain-only molecules preventing BAX- and BAK-mediated mitochondrial apoptosis. Mol. Cell 8, 705–711 (2001).

  10. 10.

    et al. Distinct BH3 domains either sensitize or activate mitochondrial apoptosis, serving as prototype cancer therapeutics. Cancer Cell 2, 183–192 (2002).

  11. 11.

    et al. Differential targeting of prosurvival Bcl-2 proteins by their BH3-only ligands allows complementary apoptotic function. Mol. Cell 17, 393–403 (2005).

  12. 12.

    et al. BH3 domains of BH3-only proteins differentially regulate Bax-mediated mitochondrial membrane permeabilization both directly and indirectly. Mol. Cell 17, 525–535 (2005).

  13. 13.

    et al. Mitochondria primed by death signals determine cellular addiction to antiapoptotic BCL-2 family members. Cancer Cell 9, 351–365 (2006).

  14. 14.

    et al. Stepwise activation of BAX and BAK by tBID, BIM, and PUMA initiates mitochondrial apoptosis. Mol. Cell 36, 487–499 (2009).

  15. 15.

    et al. BID, BIM, and PUMA are essential for activation of the BAX- and BAK-dependent cell death program. Science 330, 1390–1393 (2010).

  16. 16.

    et al. Structure of Bcl-xL-Bak peptide complex: recognition between regulators of apoptosis. Science 275, 983–986 (1997).

  17. 17.

    et al. Structural insights into the degradation of Mcl-1 induced by BH3 domains. Proc. Natl Acad. Sci. USA 104, 6217–6222 (2007).

  18. 18.

    et al. Bax crystal structures reveal how BH3 domains activate Bax and nucleate its oligomerization to induce apoptosis. Cell 152, 519–531 (2013).

  19. 19.

    et al. BID-induced structural changes in BAK promote apoptosis. Nat. Struct. Mol. Biol. 20, 589–597 (2013).

  20. 20.

    , , & Direct activation of full-length proapoptotic BAK. Proc. Natl Acad. Sci. USA 110, E986–E995 (2013).

  21. 21.

    et al. Multimodal interaction with BCL-2 family proteins underlies the proapoptotic activity of PUMA BH3. Chem. Biol. 20, 888–902 (2013).

  22. 22.

    et al. Bak core and latch domains separate during activation, and freed core domains form symmetric homodimers. Mol. Cell 55, 938–946 (2014).

  23. 23.

    et al. To trigger apoptosis, Bak exposes its BH3 domain and homodimerizes via BH3: groove interactions. Mol. Cell 30, 369–380 (2008).

  24. 24.

    , , , & BH3-triggered structural reorganization drives the activation of proapoptotic BAX. Mol. Cell 40, 481–492 (2010).

  25. 25.

    et al. Proapoptotic BAX and BAK: a requisite gateway to mitochondrial dysfunction and death. Science 292, 727–730 (2001).

  26. 26.

    et al. Bid-induced conformational change of Bax is responsible for mitochondrial cytochrome c release during apoptosis. J. Cell Biol. 144, 891–901 (1999).

  27. 27.

    et al. Apoptosis initiated when BH3 ligands engage multiple Bcl-2 homologs, not Bax or Bak. Science 315, 856–859 (2007).

  28. 28.

    et al. The combined functions of proapoptotic Bcl-2 family members Bak and Bax are essential for normal development of multiple tissues. Mol. Cell 6, 1389–1399 (2000).

  29. 29.

    & Mitochondria in apoptosis: Bcl-2 family members and mitochondrial dynamics. Dev. Cell 21, 92–101 (2011).

  30. 30.

    et al. BAX and BAK regulation of endoplasmic reticulum Ca2+: a control point for apoptosis. Science 300, 135–139 (2003).

  31. 31.

    et al. Bid, Bax, and lipids cooperate to form supramolecular openings in the outer mitochondrial membrane. Cell 111, 331–342 (2002).

  32. 32.

    et al. Membrane binding by tBid initiates an ordered series of events culminating in membrane permeabilization by Bax. Cell 135, 1074–1084 (2008).

  33. 33.

    et al. p53- and drug-induced apoptotic responses mediated by BH3-only proteins puma and noxa. Science 302, 1036–1038 (2003).

  34. 34.

    et al. Integral role of Noxa in p53-mediated apoptotic response. Genes Dev. 17, 2233–2238 (2003).

  35. 35.

    , , , & Ultraviolet radiation triggers apoptosis of fibroblasts and skin keratinocytes mainly via the BH3-only protein Noxa. J. Cell Biol. 176, 415–424 (2007).

  36. 36.

    , , & p53-dependent apoptosis modulates the cytotoxicity of anticancer agents. Cell 74, 957–967 (1993).

  37. 37.

    , , , & VDAC2 inhibits BAK activation and mitochondrial apoptosis. Science 301, 513–517 (2003).

  38. 38.

    et al. Proapoptotic Bak is sequestered by Mcl-1 and Bcl-xL, but not Bcl-2, until displaced by BH3-only proteins. Genes Dev. 19, 1294–1305 (2005).

  39. 39.

    et al. The p53-cathepsin axis cooperates with ROS to activate programmed necrotic death upon DNA damage. Proc. Natl Acad. Sci. USA 106, 1093–1098 (2009).

  40. 40.

    , , , & Bax-independent inhibition of apoptosis by Bcl-XL. Nature 379, 554–556 (1996).

  41. 41.

    et al. BAX activation is initiated at a novel interaction site. Nature 455, 1076–1081 (2008).

  42. 42.

    , , & Molecular biology of Bax and Bak activation and action. Biochim. Biophys. Acta 1813, 521–531 (2011).

  43. 43.

    et al. Bcl-xL retrotranslocates Bax from the mitochondria into the cytosol. Cell 145, 104–116 (2011).

  44. 44.

    et al. Activation of apoptosis in vivo by a hydrocarbon-stapled BH3 helix. Science 305, 1466–1470 (2004).

  45. 45.

    , , & Baxbeta: a constitutively active human Bax isoform that is under tight regulatory control by the proteasomal degradation mechanism. Mol. Cell 33, 15–29 (2009).

  46. 46.

    et al. BH3 domains other than Bim and Bid can directly activate Bax/Bak. J. Biol. Chem. 286, 491–501 (2011).

  47. 47.

    et al. Transient binding of an activator BH3 domain to the Bak BH3-binding groove initiates Bak oligomerization. J. Cell Biol. 194, 39–48 (2011).

  48. 48.

    et al. An inhibitor of Bcl-2 family proteins induces regression of solid tumours. Nature 435, 677–681 (2005).

  49. 49.

    et al. ABT-263: a potent and orally bioavailable Bcl-2 family inhibitor. Cancer Res. 68, 3421–3428 (2008).

  50. 50.

    et al. ABT-199, a potent and selective BCL-2 inhibitor, achieves antitumor activity while sparing platelets. Nat. Med. 19, 202–208 (2013).

  51. 51.

    & Targeting the B-cell lymphoma/leukemia 2 family in cancer. J. Clin. Oncol. 30, 3127–3135 (2012).

  52. 52.

    From mitochondrial biology to magic bullet: navitoclax disarms BCL-2 in chronic lymphocytic leukemia. J. Clin. Oncol. 30, 554–557 (2012).

  53. 53.

    , & Targeting BCL2 for the treatment of lymphoid malignancies. Semin. Hematol. 51, 219–227 (2014).

  54. 54.

    et al. Essential role of BAX, BAK in B cell homeostasis and prevention of autoimmune disease. Proc. Natl Acad. Sci. USA 102, 11272–11277 (2005).

  55. 55.

    et al. Proteolysis of MLL family proteins is essential for taspase1-orchestrated cell cycle progression. Genes Dev. 20, 2397–2409 (2006).

  56. 56.

    , , , & Interaction with a membrane surface triggers a reversible conformational change in Bax normally associated with induction of apoptosis. J. Biol. Chem. 278, 48935–48941 (2003).

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Acknowledgements

We apologize to all of the investigators whose research could not be appropriately cited owing to space limitation. We thank H.-F. Chen and S. Han for technical assistance. This work was supported by grants to E.H.C. from the NIH (R01CA125562) and the American Cancer Society (118518-RSG-10-030-01-CCG), and to E.G. from the NIH (R01CA178394) This work was also supported by the NIH P30CA008748.

Author information

Affiliations

  1. Human Oncology and Pathogenesis Program, Memorial Sloan Kettering Cancer Center, New York, New York 10065, USA

    • Hui-Chen Chen
    • , Masayuki Kanai
    • , Akane Inoue-Yamauchi
    • , Ho-Chou Tu
    • , Yafen Huang
    • , Shugaku Takeda
    • , Po M. Chan
    • , Yogesh Tengarai Ganesan
    • , Chung-Ping Liao
    • , James J. Hsieh
    •  & Emily H. Cheng
  2. Department of Medicine, University of Chicago, Chicago, Illinois 60637, USA

    • Decheng Ren
  3. Department of Pharmacological Sciences, Stony Brook University, Stony Brook, New York 11794, USA

    • Hyungjin Kim
  4. Department of Biochemistry, Albert Einstein College of Medicine, Bronx, New York 10461, USA

    • Denis E. Reyna
    •  & Evripidis Gavathiotis
  5. Department of Medicine, Memorial Sloan Kettering Cancer Center, New York, New York 10065, USA

    • James J. Hsieh
  6. Department of Pathology, Memorial Sloan Kettering Cancer Center, New York, New York 10065, USA

    • Emily H. Cheng
  7. Department of Pathology and Laboratory Medicine, Weill Cornell Medical College, Cornell University, New York, New York 10065, USA

    • Emily H. Cheng

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Contributions

H.-C.C. designed and conducted experiments, and analysed data. E.H.C. designed research, analysed data and supervised the project. H.-C.T., M.K., Y.H., H.K., A.I.-Y., Y.T.G. and D.E.R. conducted experiments. J.J.H. and E.G. supervised some experiments. H.C.T., D.R., P.M.C., S.T. and C.-P.L. generated essential reagents.

Competing interests

The authors declare no competing financial interests.

Corresponding author

Correspondence to Emily H. Cheng.

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DOI

https://doi.org/10.1038/ncb3236

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