The PINK1 interactor Clueless : a new player in mitochondrial dynamics

• Main Author: Anderson, C. A.
• Published: University College London (University of London) 2014
• Subjects: 615.1
• Online Access: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.626620

Dysregulation of mitochondrial dynamics is an emerging theme in neurodegenerative disorders, including Parkinson disease (PD). Autosomal recessive PD (ARPD) can be caused by mutations in the mitochondrial kinase PINK1 or the cytosolic E3 ubiquitin ligase Parkin. PINK1 and Parkin act in a common genetic pathway to control mitochondrial dynamics. To gain insights into the regulation of mitochondrial dynamics, binding partners of PINK1 were identified using different approaches: yeast two-hybrid screening of cytosolic and membrane bound forms of PINK1 and affinity purification of epitope-tagged PINK1 from a stable cell line under basal conditions and during mitochondrial stress. Many potential substrates of PINK1 were identified, including proteins with roles in mitochondrial dynamics. CluH was persistently identified in the PINK1 co-precipitation studies. CluH is a large tetratricopeptide protein that is highly conserved. CluH has previously been implicated in the regulation of mitochondrial dynamics in yeast, slime mold, plants and the fruit fly, but remains uncharacterized in mammals. I therefore investigated the expression profile of CluH in mouse tissues, and the subcellular localization in human cells using confocal microscopy. I also examined whether CluH could regulate mitochondrial morphology and function. I demonstrated that siRNA knock-down of CluH led to hyperfused mitochondria while over-expression of CluH led to fragmented mitochondria. Knock-down of CluH also resulted in decreased complex I activity, suggesting that CluH is required for mitochondrial integrity. The domains of CluH required for altering mitochondrial dynamics were also determined. Finally, I examined the interplay of CluH with the fission/fusion machinery and found that CluH can interact with fission proteins MiD49 and Drp1, consistent with a role for CluH in promoting mitochondrial fission. Taken together, these studies have identified CluH as a new player in mitochondrial dynamics, which interacts with the ARPD protein PINK1.