Mitochondrial nucleoid morphology and respiratory function are altered in Drp1-deficient HeLa cells

J Biochem. 2020 Mar 1;167(3):287-294. doi: 10.1093/jb/mvz112.


Mitochondria are dynamic organelles that frequently divide and fuse with each other. The dynamin-related GTPase protein Drp1 has a key role in mitochondrial fission. To analyse the physiological roles of Drp1 in cultured human cells, we analysed Drp1-deficient HeLa cells established by genome editing using CRISPR/Cas9. Under fluorescent microscopy, not only mitochondria were elongated but their DNA (mtDNA) nucleoids were extremely enlarged in bulb-like mitochondrial structures ('mito-bulbs') in the Drp1-deficient HeLa cells. We further found that respiratory activity, as measured by oxygen consumption rates, was severely repressed in Drp1-deficient HeLa cells and that this was reversible by the co-repression of mitochondrial fusion factors. Although mtDNA copy number was not affected, several respiratory subunits were repressed in Drp1-deficient HeLa cells. These results suggest that mitochondrial fission is required for the maintenance of active respiratory activity and the morphology of mtDNA nucleoids in human cells.

Keywords: GTPase; membrane dynamics; mitochondria; mtDNA; respiratory complex.

MeSH terms

  • CRISPR-Cas Systems
  • Cell Respiration / genetics
  • DNA, Mitochondrial / genetics
  • DNA, Mitochondrial / metabolism*
  • Dynamins / genetics
  • Dynamins / metabolism*
  • Gene Knockout Techniques
  • HeLa Cells
  • Humans
  • Microscopy, Fluorescence
  • Mitochondria / genetics
  • Mitochondria / metabolism*
  • Mitochondria / ultrastructure
  • Mitochondrial Dynamics / genetics
  • Mitochondrial Dynamics / physiology
  • RNA, Small Interfering


  • DNA, Mitochondrial
  • RNA, Small Interfering
  • DNM1L protein, human
  • Dynamins