Intercellular Mitochondrial Transfer as a Rescue Mechanism in Response to Protein Import Failure

Mitochondria are the powerhouses of eukaryotic cells, composed mostly of nuclear-encoded proteins imported from the cytosol. Thus, problems with the import machinery will disrupt their regenerative capacity and the cell’s energy (ATP) supplies–particularly troublesome for energy demanding cells like neurons and myocytes. Unsurprisingly then, dysfunctional import is implicated in disease. This study explores the consequences of import failure in mammalian cells; wherein, blocking the import machinery has profound effects on mitochondrial ultra-structure and dynamics, but, surprisingly, does not impact import. The explanation is an astonishing response involving intercellular mitochondrial transfer via tunnelling nanotubes: for the import of healthy mitochondria and jettisoning of those with jammed import sites. These observations support the existence of a widespread mechanism for the rescue of mitochondrial protein import failure. One-Sentence Summary A mitochondrial import rescue mechanism involving intercellular mitochondrial transport through tunneling nanotubes (TNTs).