Parkinson’s Disease (PD) related genes PINK1, a protein kinase , and Parkin, an E3
ubiquitin ligase , operate within the same pathway [3-5], which controls, via specific elimination of
dysfunctional mitochondria, the quality of the organelle network . Parkin translocates to impaired
mitochondria and drives their elimination via autophagy, a process known as mitophagy . PINK1
regulates Parkin translocation through a not yet completely understood mechanism [7, 8].
Mitochondrial outer membrane proteins Mitofusin (MFN), VDAC, Fis1 and TOM20 were found to
be targets for Parkin mediated ubiquitination [9-11]. By adding ubiquitin molecules to its targets expressed on
mitochondria, Parkin tags and selects dysfunctional mitochondria for clearance, contributing to maintain a functional and
healthy mitochondrial network. Abnormal accumulation of misfolded proteins and unfunctional mitochondria is a
characteristic hallmark of PD pathology. Therefore a therapeutic approach to enhance clearance of misfolded proteins and
potentiate the ubiquitin-proteosome system (UPS) could be instrumental to ameliorate the progression of the disease.
Recently, much effort has been put to identify specific de-ubiquitinating enzymes (DUBs) that oppose Parkin in the
ubiquitination of its targets. Similar to other post-translational modifications, such as phosphorylation and acetylation,
ubiquitination is also a reversible modification, mediated by a large family of DUBs . DUBs inhibitors or activators
can affect cellular response to stimuli that induce mitophagy via ubiquitination of mitochondrial outer membrane proteins
MFN, VDAC, Fis1 and TOM20. In this respect, the identification of a Parkin-opposing DUB in the regulation of
mitophagy, might be instrumental to develop specific isopeptidase inhibitors or activators that can modulate the
fundamental biological process of mitochondria clearance and impact on cell survival.