Robust autophagy/mitophagy persists during mitosis.

From microscopic observations of autophagosome content it has been argued that autophagy is shut down during mitosis to protect the relative short-lived organelles spindle and chromosomes from the process while they are contiguous with cytosol. However, without autophagy, buildup of dysfunctional mitochondria arising from the intense energy demands of mitosis potentially poses a hazard to accurate partition of chromosomes. Here we show using biochemical markers of autophagosomes and mitophagosomes and a blockade at the lysosomal clearance step that autophagy/mitophagy persists during mitosis at robust levels equal to interphase. This suggests a mechanism that insulates normal spindle and chromosomes from autophagy and potentially recognition of defects in spindle and chromosomes by the autophagic process.