Figure 1.

Mitochondria quality control pathways maintain mitochondrial function. Mitofusin 1 and 2 (MFN1/2) and optic atrophy protein 1 (OPA1) mediate mitochondrial fusion to produce an interconnected healthy mitochondrial network. Mitochondrial fission depends on dynamin-related protein 1 (DRP1) and mitochondrial fission factor (MFF) proteins. Fragmented dysfunctional mitochondria are removed by mitophagy. Bcl2/adenovirus E1B 19 kDa protein-interacting protein 3 (BNIP3) and NIP3-like-proteinX (NIX) are mitophagy receptors that bind to microtubule-associated protein 1 light chain 3 (LC3) to tether mitochondria to the autophagosome. PTEN-induced kinase 1 (PINK1) accumulates on depolarized mitochondria surface, where it phosphorylates ubiquitinated outer mitochondrial membrane (OMM) proteins and Parkin. Parkin will further promote the ubiquitination of the OMM proteins. The p62/SQSTM1 adaptor can recognize the ubiquitinated proteins to initiate mitophagy. U: ubiquitin. Figure was created with BioRender.com