Extra-mitochondrial prosurvival BCL-2 proteins regulate gene transcription by inhibiting the SUFU tumour suppressor

  • Nat Cell Biol. 2017 Oct;19(10):1226-1236. doi: 10.1038/ncb3616.
Xiaofeng Wu  1 Li-Shu Zhang  1 Jason Toombs  2  3 Yi-Chun Kuo  3  4 John Tyler Piazza  1 Rubina Tuladhar  1 Quinn Barrett  1 Chih-Wei Fan  1 Xuewu Zhang  3  4 Loren D Walensky  5  6 Marcel Kool  7  8 Steven Y Cheng  9  10 Rolf Brekken  2  3 Joseph T Opferman  11 Douglas R Green  12 Tudor Moldoveanu  13  14 Lawrence Lum  1
Affiliations
  • 1. Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, Texas 75390, USA.
  • 2. Department of Surgery, University of Texas Southwestern Medical Center, Dallas, Texas 75390, USA.
  • 3. Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, Texas 75390, USA.
  • 4. Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, Texas 75390, USA.
  • 5. Department of Pediatric Oncology, Dana Farber Cancer Institute, Boston, Massachusetts 02215, USA.
  • 6. Department of Pediatrics, Harvard Medical School, 450 Brookline Avenue, Boston, Massachusetts 02215, USA.
  • 7. Division of Pediatric Neurooncology, German Cancer Research Center (DKFZ), Im Neuenheimer Feld 280, Heidelberg 69120, Germany.
  • 8. German Cancer Consortium (DKTK), Core Center Heidelberg, 69120 Heidelberg, Germany.
  • 9. Department of Developmental Genetics, Nanjing Medical University, 140 Hanzhong Road, Nanjing, Jiangsu 210029, China.
  • 10. Center for Regenerative Medicine, Nanjing Medical University, 140 Hanzhong Road, Nanjing, Jiangsu 210029, China.
  • 11. Cell &Molecular Biology Department, St Jude Children's Hospital, Memphis, Tennessee 38105, USA.
  • 12. Immunology Department, St Jude Children's Hospital, Memphis, Tennessee 38105, USA.
  • 13. Structural Biology Department, St Jude Children's Hospital, Memphis, Tennessee 38105, USA.
  • 14. Chemical Biology and Therapeutics Department, St Jude Children's Hospital, Memphis, Tennessee 38105, USA.
Abstract

Direct interactions between pro- and anti-apoptotic Bcl-2 Family members form the basis of cell death decision-making at the outer mitochondrial membrane (OMM). Here we report that three anti-apoptotic Bcl-2 proteins (Mcl-1, Bcl-2 and Bcl-xL) found untethered from the OMM function as transcriptional regulators of a prosurvival and growth program. Anti-apoptotic Bcl-2 proteins engage a Bcl-2 homology (BH) domain sequence found in SUFU (suppressor of fused), a tumour suppressor and antagonist of the Gli DNA-binding proteins. Bcl-2 proteins directly promote SUFU turnover, inhibit SUFU-GLI interaction, and induce the expression of the Gli target genes Bcl-2, Mcl-1 and Bcl-xL. Anti-apoptotic Bcl-2 protein/SUFU feedforward signalling promotes Cancer cell survival and growth, and can be disabled with BH3 mimetics-small molecules that target anti-apoptotic Bcl-2 proteins. Our findings delineate a chemical strategy for countering drug resistance in GLI-associated tumours and reveal unanticipated functions for Bcl-2 proteins as transcriptional regulators.

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