Mitophagy - mitochondrial quality control

Damaged or unneeded mitochondria are removed from the cell by mitophagy, a specialised form of autophagy.  Mitophagy uses specific signals, including ubiquitination mediated by the E3 ligase Parkin, to recognise and remove damaged mitochondria.  However, much about the process and how it differs from other autophagy subtypes remains to be determined.

Expression of a GFP-tagged protein in the lower cell results in fragmentation and condensation of mitochondria (red) to the peri-nuclear area. Colocalisation of green GFP signal and mitochondria can be seen.My interest in mitophagy came about as a result of studying anti-bacterial autophagy.  Autophagy of mitochondria and bacteria are similar in many aspects, including: close confirmation of the autophagic vacuole to the cargo shape; specific recognition signals, including ubiquitination; capture of a membrane-bound organelle of similar size and shape.

Given the shared evolutionary history of mitochondria and bacteria, it is possible that autophagic mechanisms are shared between these targets. We have some preliminary findings suggesting that overexpression of specific human proteins can trigger mitochondrial fragmentation and autophagy - this forms the basis for our current investigations.