MLH1 deficiency leads to deregulated mitochondrial metabolism

Cell Death Dis. 2019 Oct 22;10(11):795. doi: 10.1038/s41419-019-2018-y.


The DNA mismatch repair (MMR) pathway is responsible for the repair of base-base mismatches and insertion/deletion loops that arise during DNA replication. MMR deficiency is currently estimated to be present in 15-17% of colorectal cancer cases and 30% of endometrial cancers. MLH1 is one of the key proteins involved in the MMR pathway. Inhibition of a number of mitochondrial genes, including POLG and PINK1 can induce synthetic lethality in MLH1-deficient cells. Here we demonstrate for the first time that loss of MLH1 is associated with a deregulated mitochondrial metabolism, with reduced basal oxygen consumption rate and reduced spare respiratory capacity. Furthermore, MLH1-deficient cells display a significant reduction in activity of the respiratory chain Complex I. As a functional consequence of this perturbed mitochondrial metabolism, MLH1-deficient cells have a reduced anti-oxidant response and show increased sensitivity to reactive oxidative species (ROS)-inducing drugs. Taken together, our results provide evidence for an intrinsic mitochondrial dysfunction in MLH1-deficient cells and a requirement for MLH1 in the regulation of mitochondrial function.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Colorectal Neoplasms / genetics
  • Colorectal Neoplasms / metabolism
  • Colorectal Neoplasms / pathology
  • DNA Mismatch Repair
  • Electron Transport Complex I / antagonists & inhibitors
  • Electron Transport Complex I / genetics
  • Electron Transport Complex I / metabolism
  • Endometrial Neoplasms / genetics
  • Endometrial Neoplasms / metabolism
  • Endometrial Neoplasms / pathology
  • Female
  • HCT116 Cells
  • HT29 Cells
  • Humans
  • Male
  • Mitochondria / genetics
  • Mitochondria / metabolism*
  • MutL Protein Homolog 1 / deficiency*
  • MutL Protein Homolog 1 / genetics
  • MutL Protein Homolog 1 / metabolism
  • Mutation
  • Neoplasms / genetics
  • Neoplasms / metabolism
  • Neoplasms / pathology
  • Ovarian Neoplasms / genetics
  • Ovarian Neoplasms / metabolism
  • Ovarian Neoplasms / pathology
  • Rotenone / pharmacology
  • Transfection


  • MLH1 protein, human
  • Rotenone
  • MutL Protein Homolog 1
  • Electron Transport Complex I
  • NDUFA9 protein, human