Inhibiting mitochondrial-dependent proteolysis of Mcl-1 promotes resistance to DNA damage

Cell Cycle. 2012 Jan 1;11(1):88-98. doi: 10.4161/cc.11.1.18408. Epub 2012 Jan 1.

Abstract

Elimination of myeloid leukemia cell 1 (Mcl-1) is an early event in the onset of cell death following DNA damage and, in many settings, plays a critical role in dictating the success of chemotherapeutic agents. Following DNA damage, Mcl-1 is rapidly and efficiently targeted to the 26S proteasome through the action of E3 ubiquitin ligases. Tumors having acquired lesions that lead to stabilization of Mcl-1 are highly aggressive and have a poorer prognosis. Herein, we further characterize an additional mechanism of Mcl-1 proteolysis that is proteasome-independent but mitochondrial-dependent. A mitochondrial targeting signal located in the N terminus of Mcl-1 is essential for targeting Mcl-1 to this alternative degradative avenue. We demonstrate that the Akt/mTORC1 survival pathway protects Mcl-1 from mitochondrial-dependent proteolysis. Disrupting Mcl-1 inner mitochondrial targeting improves the pro-survival capacity of Mcl-1 both ex vivo and in vivo in the well-characterized mouse Eμ-Myc lymphoma model. Our data uncover an important relationship between the mitochondria and the Mcl-1 N terminus in dictating cell fate following DNA damage.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Antineoplastic Agents / pharmacology
  • Cell Line, Tumor
  • DNA Damage*
  • Disease Models, Animal
  • Lymphoma / drug therapy
  • Lymphoma / metabolism
  • Lymphoma / pathology
  • Mice
  • Mitochondria / metabolism*
  • Mutagenesis
  • Myeloid Cell Leukemia Sequence 1 Protein
  • Proteasome Endopeptidase Complex / metabolism
  • Proteolysis
  • Proto-Oncogene Proteins c-akt / metabolism
  • Proto-Oncogene Proteins c-bcl-2 / genetics
  • Proto-Oncogene Proteins c-bcl-2 / metabolism*
  • Signal Transduction
  • TOR Serine-Threonine Kinases / metabolism

Substances

  • Antineoplastic Agents
  • Mcl1 protein, mouse
  • Myeloid Cell Leukemia Sequence 1 Protein
  • Proto-Oncogene Proteins c-bcl-2
  • Proto-Oncogene Proteins c-akt
  • TOR Serine-Threonine Kinases
  • Proteasome Endopeptidase Complex