Parkin loss leads to PARIS-dependent declines in mitochondrial mass and respiration

Abstract

Mutations in parkin lead to early-onset autosomal recessive Parkinson's disease (PD) and inactivation of parkin is thought to contribute to sporadic PD. Adult knockout of parkin in the ventral midbrain of mice leads to an age-dependent loss of dopamine neurons that is dependent on the accumulation of parkin interacting substrate (PARIS), zinc finger protein 746 (ZNF746), and its transcriptional repression of PGC-1α. Here we show that adult knockout of parkin in mouse ventral midbrain leads to decreases in mitochondrial size, number, and protein markers consistent with a defect in mitochondrial biogenesis. This decrease in mitochondrial mass is prevented by short hairpin RNA knockdown of PARIS. PARIS overexpression in mouse ventral midbrain leads to decreases in mitochondrial number and protein markers and PGC-1α-dependent deficits in mitochondrial respiration. Taken together, these results suggest that parkin loss impairs mitochondrial biogenesis, leading to declining function of the mitochondrial pool and cell death. Recently, the parkin interacting substrate (PARIS) also known as zinc finger protein 746 (ZNF746) was shown to be required for loss of DA neurons in adult conditional parkin knockout (KO) mice (19). PARIS is polyubiquitinated by parkin via lysine-48 targeting it for ubiquitin proteasomal degradation. Deletion of parkin in adult mice leads to an age-dependent progressive loss of DA neurons that is due to the accumulation of PARIS because depletion of PARIS in adult conditional parkin knockout mice prevents the loss of DA neurons (19). PARIS is a transcriptional repressor that regulates the expression of peroxisome proliferator-activated receptor gamma, coactivator 1α (PGC-1α), a master coregulator of mitochondrial function, biogenesis, and mitochondrial oxidative stress management (19,20). In adult conditional parkin knockout mice, there is a reduction in PGC-1α levels that is dependent on PARIS because reduction in PARIS reverses the reduction in PGC-1α levels (19). PARIS overexpression, at levels equivalent to those in the adult conditional parkin knockout mice, also leads to defects in PGC-1α and causes the selective loss of DA neurons (19). PGC-1α overexpression prevents the defects in PGC-1α signaling and the loss of DA neurons, suggesting that PARIS kills DA neurons in a PGC-1α-dependent fashion (19).Because PGC-1α is a master coregulator of mitochondrial function and mitochondrial defects are a consistent feature of PD, mitochondria were assessed in the adult conditional parkin knockout mice. Here we show that adult conditional knockout of parkin leads to reductions in mitochondrial mass that are dependent upon PARIS. Moreover, PARIS accumulation leads to substantial deficits in mitochondrial respiration that are PGC-1α dependent. Our findings are consistent with parkin regulation of mitochondrial biogenesis. ResultsReduced Mitochondrial Size and Number in Adult Conditional Parkin Knockouts. Adult conditional parkin knockout mice were generated as previously described by injecting a lentiviru...

Parkin-dependent regulation of the MCU complex component MICU1

“…In search of a potential E3 ubiquitin ligase involved in the regulation of the basal level of the MCU complex components, we focused our attention on the PD-related protein Parkin, which, besides its role in the execution of mitophagy, has been shown to regulate the level of several proteins involved in the quality control of different mitochondria-related activities, such as biogenesis, integrity, respiration and calcium homeostasis 28–30,45 . To this aim, we transiently expressed flag-tagged MCU, HA-tagged MICU1 and Flag-tagged MICU2 in HeLa cells either alone or together with WT Parkin or the PD-related mutant G430D (characterized by abolished in vitro and in vivo ligase activity, due to the destabilization of the reactive cysteine C431) 46–50 , or the ΔUbl Parkin mutant (missing the Ubl domain) 51–54 .…”

Trumping neurodegeneration: Targeting common pathways regulated by autosomal recessive Parkinson's disease genes

“…PARIS seems to be particularly important in the PINK1 and parkin pathway of neurodegeneration in PD since a reduction in PARIS levels rescues the neurodegeneration in adult conditional PINK1 knockdown mice (Lee et al, 2017). Moreover, defects in mitochondrial biogenesis drive the loss of DA neurons since adult conditional parkin KO mice have primary defects in mitochondrial biogenesis in the absence of measurable defects in mitophagy, consistent with rescue of degeneration by reducing PARIS levels (Stevens et al, 2015). Because PARIS is one of the only known transcriptional suppressors of the key mitochondrial biogenesis regulator PGC-1α, it is an attractive therapeutic target.…”

PINK1 Primes Parkin-Mediated Ubiquitination of PARIS in Dopaminergic Neuronal Survival

“…Recently, a number of co-substrates for PINK1 and parkin have been identified tying these proteins to multiple aspects of mitochondrial quality control (Pickrell and Youle, 2015; Scarffe et al, 2014; Winklhofer, 2014). PARIS (ZNF746) is a pathologic parkin substrate, which is increased in sporadic and familial PD brains and is responsible for DA neuronal loss in mouse models of parkin inactivation (Shin et al, 2011; Siddiqui et al, 2015; Siddiqui et al, 2016; Stevens et al, 2015). PARIS accumulation represses the transcriptional coactivator, peroxisome proliferator-activated receptor gamma coactivator-1-alpha (PGC-1α), which is critical for DA neuron survival (Ciron et al, 2015; Jiang et al, 2016; Mudo et al, 2012; Zheng et al, 2010).…”

“…Since parkin and PINK1 are thought to regulate DA neuronal survival in a common pathway (Corti and Brice, 2013; Rochet et al, 2012; Scarffe et al, 2014), and regulation of PARIS by parkin is critical for DA cell survival (Shin et al, 2011; Siddiqui et al, 2015; Siddiqui et al, 2016; Stevens et al, 2015; Winklhofer, 2014), we investigated whether PINK1 plays any role in the regulation of PARIS. Here we show that PINK1 is a priming kinase for parkin-mediated PARIS ubiquitination and clearance.…”