Effects of insulin-like growth factor-1 (IGF-1) receptor signaling on rates of apoptosis in retina of dopamine beta hydroxylase (Dbh−/−) knockout mice

We have investigated whether insulin-like growth factor-1 (IGF-1) receptor signaling alters rates of apoptosis in dopamine beta-hydroxylase (Dbh^?/?) knockout mice. Retinal lysates from Dbh^?/? and their heterozygote littermates (Dbh^+/?) were used to examine the role of norepinephrine in the regulation of IGF-1 receptor signaling and apoptosis in the retina. Western blot analysis was done for protein levels of total and phosphorylated IGF-1 receptor, insulin receptor substrate-1 (IRS-1), insulin receptor substrate-2 (IRS-2), and Akt. A caspase 3 ELISA and dopamine ELISA were done on retinal lysates. To verify which regions of the retina were undergoing apoptosis, TUNEL labeling was performed. No changes in dopamine were noted between the KO and heterozygote mice. IGF-1 receptor phosphorylation was significantly decreased in Dbh^?/? mice as compared to their heterozygote littermates (P < 0.05 vs. heterozygous mice). IRS-1 protein phosphorylation was significantly decreased in KO mice (P < 0.05 vs. heterozygous mice), while no significant changes were noted in IRS-2 protein phosphorylation. Akt protein phosphorylation was also reduced in the KO mice, likely leading to increased cleaved caspase 3 levels. The increase in apoptosis in the Dbh^?/? mice occurred predominantly in the inner retina. Our results suggest that IGF-1 receptor signaling is reduced in the retina of mice with dysfunctional adrenergic receptor signaling. The data also indicate that IGF-1 receptor signaling occurs primarily through IRS-1, rather than IRS-2. The reduction in Akt phosphorylation, likely through reduced IGF-1 receptor signaling, could explain the increase in cleaved caspase 3, leading to apoptosis. These results suggest that alterations in adrenergic receptor signaling modulate IGF-1 receptor signaling, which can regulate apoptosis in the retina.     

Olfactory dysfunction in Parkinsonism caused by PINK1 mutations

Hyposmia is a common nonmotor feature of Parkinson's disease (PD) and has been variably detected in monogenic Parkinsonisms. To assess olfactory dysfunction in PINK1‐related Parkinsonism, we evaluated olfactory detection threshold, odor discrimination, and odor identification in five groups of subjects: sporadic PD (n = 19), PINK1 homozygous (n = 7), and heterozygous (n = 6) parkinsonian patients, asymptomatic PINK1 heterozygous carriers (n = 12), and Italian healthy subjects (n = 67). All affected subjects and all healthy heterozygotes but one resulted hyposmic, with most patients in the range of functional anosmia or severe hyposmia. Detection threshold was more preserved and discrimination more impaired in patients with PINK1 mutations than in PD cases. Alterations of detection and discrimination were observed also in PINK1 asymptomatic heterozygotes. On the contrary, odor identification appeared to be mostly related to the disease status, as it was impaired in nearly all patients (including PD and PINK1 cases) and preserved in healthy heterozygotes. Our data indicate that olfactory dysfunction is common in PINK1 Parkinsonism and consists typically in defective odor identification and discrimination. A milder olfactory deficit, mostly involving discrimination, can be found in asymptomatic heterozygotes, possibly indicating an underlying preclinical neurodegenerative process. © 2009 Movement Disorder Society     

Mitochondrial membrane potential decrease caused by loss of PINK1 is not due to proton leak,but to respiratory chain defects

Mutations in PTEN-induced putative kinase 1 (PINK1) cause a recessive form of Parkinson's disease (PD). PINK1 is associated with mitochondrial quality control and its partial knock-down induces mitochondrial dysfunction including decreased membrane potential and increased vulnerability against mitochondrial toxins, but the exact function of PINK1 in mitochondria has not been investigated using cells with null expression of PINK1. Here, we show that loss of PINK1 caused mitochondrial dysfunction. In PINK1-deficient (PINK1^?/?) mouse embryonic fibroblasts (MEFs), mitochondrial membrane potential and cellular ATP levels were decreased compared with those in littermate wild-type MEFs. However, mitochondrial proton leak, which reduces membrane potential in the absence of ATP synthesis, was not altered by loss of PINK1. Instead, activity of the respiratory chain, which produces the membrane potential by oxidizing substrates using oxygen, declined. H₂O₂ production rate by PINK1^?/? mitochondria was lower than PINK1^+/+ mitochondria as a consequence of decreased oxygen consumption rate, while the proportion (H₂O₂ production rate per oxygen consumption rate) was higher. These results suggest that mitochondrial dysfunctions in PD pathogenesis are caused not by proton leak, but by respiratory chain defects.     

Neuropathological findings in PINK1-associated Parkinson's disease

IntroductionBiallelic mutations in PTEN-induced putative kinase 1 (PINK1) is a relatively common cause of autosomal recessive early-onset Parkinson's disease (PD). However, only three PINK1 patients with brain autopsy have been reported in the literature.MethodsWe describe the clinical and pathological characteristics of a patient with early-onset PD. We screened for copy number variants SNCA, PRKN, PINK1, DJ-1, ATP13A2, LPA and TNFRSF9 by multiplex ligation-dependent probe amplification (MLPA), and subsequently we performed whole-exome sequencing.ResultsClinically the patient presented with typical parkinsonism that responded well to levodopa. After 23 years of disease she had a bilateral GPi deep brain stimulation (DBS) surgery. Genetic analyses revealed a heterozygous exon 4–5 deletion and a homozygous exon 1 [c. 230T > C (p.Leu77Pro)] mutation in PINK1. Post-mortem neuropathological examination after more than 30 years of disease revealed gliosis and a large loss of melanin-containing neurons in the substantia nigra. Lewy body pathology was evident in substantia nigra, temporal cortex, locus coeruleus and the parahippocampal region.ConclusionWe describe the first clinical and pathological characterization of a PINK1 patient with a typical disease presentation and long disease duration. Previous reports describe two patients with Lewy-related pathologies, albeit with differential distribution, and one patient with no Lewy-related pathology. Hence, it seems that only two patients with parkinsonism due to mutations in PINK1 are consistent with α-synucleinopathy distribution like that seen in the majority of cases with sporadic PD. Our data further extend the clinicopathological characterization of PINK1-associated PD.     

PARK13 regulates PINK1 and subcellular relocation patterns under oxidative stress in neurons

Parkinson's disease (PD) is a progressive and irreversible neurodegenerative disorder coupled to selective degeneration of dopamine‐producing neurons in the substantia nigra. The majority of PD incidents are sporadic, but monogenic cases account for 5–10% of cases. Mutations in PINK1 cause autosomal recessive forms of early‐onset PD, and PINK1 stimulates Omi/HtrA2/PARK13 protease activity when both proteins act as neuroprotective components in the same stress pathway. Studies on PINK1 and PARK13 have concentrated on phosphorylation‐dependent PINK1‐mediated activation of PARK13 and mitochondrial functions, because both proteins are classically viewed as mitochondrial. Although PARK13‐mediated protective mechanisms are at least in part regulated by PINK1, little is known concerning how these two proteins are regulated in different subcellular compartments or, indeed, the influence of PARK13 on PINK1 characteristics. We show that PARK13 localizes to a variety of subcellular locations in neuronal cells and that PINK1, although more restrictive, also localizes to locations other than those previously reported. We demonstrate that PARK13 accumulation leads to a concomitant accumulation of PINK1 and that the increase in PINK1 levels is compartmental specific, indicating a correlative relationship between the two proteins. Moreover, we show that PARK13 and PINK1 protein levels accumulate in response to H₂O₂ and L‐DOPA treatments in a subcellular fashion and that both proteins show relocation to the cytoskeleton in response to H₂O₂. This H₂O₂‐mediated relocation is abolished by PARK13 overexpression. This study shows that PARK13 and PINK1 are subcellular‐specific, but dynamic, proteins with a reciprocal molecular relationship providing new insight into the complexity of PD. © 2014 Wiley Periodicals, Inc.     

Molecular interaction between parkin and PINK1 in mammalian neuronal cells

Parkinson's disease (PD) is characterized by the deterioration of dopaminergic neurons in the pars compacta of substantia nigra and the formation of intraneuronal protein inclusions. The etiology of PD is not known, but the recent identification of several mutation genes in familial PD has provided a rich understanding of the molecular mechanisms of PD pathology. Mutations in PTEN-induced putative kinase 1 (PINK1) and parkin are linked to early-onset autosomal recessive forms of familial PD. Here we show molecular and functional interactions between parkin and PINK1. Parkin selectively binds to PINK1 and upregulates PINK1 levels. In addition, PINK1 reduces the solubility of parkin, which induces the formation of microtubule-dependent cytoplasmic aggresomes. Our findings reveal that parkin and PINK1 affect each other's stability, solubility and tendency to form aggresomes, and have important implications regarding the formation of Lewy bodies.     

PINK1 phosphorylates transglutaminase 2 and blocks its proteasomal degradation

Parkinson's disease (PD) is characterized by progressive dopaminergic neuronal loss and the formation of abnormal protein aggregates, referred to as Lewy bodies (LBs). PINK1 is a serine/threonine protein kinase that protects cells from stress‐induced mitochondrial dysfunction. PINK1 gene mutations cause one form of autosomal recessive early‐onset PD. Transglutaminase 2 (TG2) is an intracellular protein cross‐linking enzyme that has an important role in LB formation during PD pathogenesis. This study identifies PINK1 as a novel TG2 binding partner and shows that PINK1 stabilizes the half‐life of TG2 via inhibition of TG2 ubiquitination and subsequent proteasomal degradation. PINK1 affects TG2 stability in a kinase‐dependent manner. In addition, PINK1 directly phosphorylates TG2 in carbonyl cyanide m‐chlorophenyl hydrazine‐induced mitochondrial damaged states, thereby enhancing TG2 accumulation and intracellular protein cross‐linking products. This study further confirms the functional link between upstream PINK1 and downstream TG2 in Drosophila melanogaster. These data suggest that PINK1 positively regulates TG2 activity, which may be closely associated with aggresome formation in neuronal cells. © 2014 Wiley Periodicals, Inc.     

Hydrogen peroxide attenuates the prosurvival signaling of insulin-like growth factor-1 through two pathways

Although it has been well established that oxidative stress triggering a variety of signaling pathways leads to cell death, little attention has been paid to how these pathways affect prosurvival factors such as insulin-like growth factor-1 (IGF-1). In this study, we found that the prosurvival signaling of IGF-1 was attenuated by H2O2. To study the mechanism underlying this phenomenon, cells pretreated with Trolox or various glutamate receptor antagonists [i.e. N-methyl-D-aspartate (NMDA) receptor antagonist dizocilpine maleate (MK-801), non-NMDA receptor antagonist 6,7-dinitroquinoxaline-2,3-dione (DNQX), metabolic glutamate receptor antagonists LY341495 and CPCCOEt] were exposed to H2O2, and then stimulated by IGF-1. The phosphorylation statuses of IGF-1 receptors, Akt and ERK, were determined by western blotting, and cell viability was analyzed by an MTT assay. IGF-1 exerted a potent neuroprotective effect against B27 deprivation, and this effect was abolished by 100 μM H2O2. Meanwhile, the phosphorylation of IGF-1 receptors, Akt and ERK, was attenuated. Moreover, the phosphorylation of Akt was more susceptible to H2O2 insult than IGF-1 receptors. MK-801 increased the phosphorylation of IGF-1 receptors and its downstream target Akt, and thereby promoted cell survival, whereas the other glutamate receptor antagonists exerted no effect. Antioxidant Trolox did not restore IGF-1 signaling, but it increased Akt phosphorylation and also increased cell viability. These results showed that H2O2 impaired IGF-1 prosurvival signaling through two pathways. One pathway disrupted the autophosphorylation of IGF-1 receptors through NMDA receptors and the other directly dephosphorylated Akt.     

Animal models for familial Parkinson's disease]

Parkinson's disease (PD) is the second most common neurodegenerative disorder among elderly people. 5-10% of PD cases are familial and presumably hereditary forms. Based on the genes responsible for familial PD, genetic PD animal models were produced and provided invaluable information as to the pathogenetic mechanisms of PD. Missense mutations or gene multiplications of alpha-synuclein lead to autosomal dominant form of familial PD termed PARK1 or PARK4, respectively. Transgenic (Tg) mice expressing mutant of wild-type alpha-synuclein replicated main clinical features of PD including Lewy body-like aggregate formation. Inactivation of Parkin E3 enzyme leads to autosomal recessive form of PD without Lewy body formation. We have identified Pael-R as a substrate of Parkin. Accumulation of Pael-R induced by Parkin deletion evokes endoplasmic reticulum (ER) stress, resulting in cell death in cultured cells, Pael-R Tg Drosophila and Parkin-knockout crossed with Pael-R Tg mice. Recently Parkin-deficient and PTEN-induced kinase 1 (PINK1)-deficient flies showed almost identical phenotype: muscle and sperm degeneration accompanied by mitochondrial abnormalities. PINK1 is the gene for PARK6, an autosomal recessive PD. Interestingly, overexpression of Parkin rescued the phenotype of PINK1-deleted fly and Parkin/PINK1 double knockout Drosophila did not aggravated the phenotype of either Parkin or PINK1 single knockouts, indicating that Parkin and PINK1 are located in the common signaling pathway, in which Parkin works downstream of PINK1. Further studies on familial PD animal models will elucidate the roles and relationships of ubiquitin-proteasome system, endoplasmic reticulum and mitochondria in the pathogenesis of PD.     

Frequent spontaneous seizures followed by spatial working memory/anxiety deficits in mice lacking sphingosine 1-phosphate receptor 2

The diverse physiological effects of sphingosine 1-phosphate (S1P) are mostly mediated by its five cognate G protein-coupled receptors, S1P₁-S1P₅, which have attracted much attention as future drug targets. To gain insight into S1P₂-mediated signaling, we analyzed frequent spontaneous seizures in S1P₂-deficient (S1P₂^−/−) mice obtained after several backcrosses onto a C57BL/6N background. Full-time video recording of 120 S1P₂^−/− mice identified 420 seizures both day and night between postnatal days 25 and 45, which were accompanied by high-voltage synchronized cortical discharges and a series of typical episodes: wild run, tonic-clonic convulsion, freezing, and, occasionally, death. Nearly 40% of 224 S1P₂^−/− mice died after such seizures, while the remaining 60% of the mice survived to adulthood; however, approximately half of the deliveries from S1P₂^−/− pregnant mice resulted in neonatal death. In situ hybridization revealed exclusive s1p₂ expression in the hippocampal pyramidal/granular neurons of wild-type mice, and immunohistochemistry/microarray analyses identified enhanced gliosis in the whole hippocampus and its neighboring neocortex in seizure-prone adult S1P₂^−/− mice. Seizure-prone adult S1P₂^−/− mice displayed impaired spatial working memory in the eight-arm radial maze test and increased anxiety in the elevated plus maze test, whereas their passive avoidance learning memory performance in the step-through test and hippocampal long-term potentiation was indistinguishable from that of wild-type mice. Our findings suggest that blockade of S1P₂ signaling may cause seizures/hippocampal insults and impair some specific central nervous system functions.     

Insulin and IGF-1 regularize energy metabolites in neural cells expressing full-length mutant huntingtin

Huntington's disease (HD) is an autosomal dominant neurodegenerative disorder linked to the expression of mutant huntingtin. Bioenergetic dysfunction has been described to contribute to HD pathogenesis. Thus, treatment paradigms aimed to ameliorate energy deficits appear to be suitable candidates in HD. In previous studies, we observed protective effects of insulin growth factor-1 (IGF-1) in YAC128 and R6/2 mice, two HD mouse models, whereas IGF-1 and/or insulin halted mitochondrial-driven oxidative stress in mutant striatal cells and mitochondrial dysfunction in HD human lymphoblasts. Here, we analyzed the effect of IGF-1 versus insulin on energy metabolic parameters using striatal cells derived from HD knock-in mice and primary cortical cultures from YAC128 mice. STHdh^Q111/Q111 cells exhibited decreased ATP/ADP ratio and increased phosphocreatine levels. Moreover, pyruvate levels were increased in mutant cells, most probably in consequence of a decrease in pyruvate dehydrogenase (PDH) protein expression and increased PDH phosphorylation, reflecting its inactivation. Insulin and IGF-1 treatment significantly decreased phosphocreatine levels, whereas IGF-1 only decreased pyruvate levels in mutant cells. In a different scenario, primary cortical cultures derived from YAC128 mice also displayed energetic abnormalities. We observed a decrease in both ATP/ADP and phosphocreatine levels, which were prevented following exposure to insulin or IGF-1. Furthermore, decreased lactate levels in YAC128 cultures occurred concomitantly with a decline in lactate dehydrogenase activity, which was ameliorated with both insulin and IGF-1. These data demonstrate differential HD-associated metabolic dysfunction in striatal cell lines and primary cortical cultures, both of which being alleviated by insulin and IGF-1.     

Incidence of mutations in the PARK2, PINK1, PARK7 genes in Polish early-onset Parkinson disease patients

Background and purposeParkinson disease (PD) is a complex disease, comprising genetic and environmental factors. Despite the vast majority of sporadic cases, three genes, i.e. PARK2, PINK1 and PARK7 (DJ-1), have been identified as responsible for the autosomal recessive form of early-onset Parkinson disease (EO-PD). Identified changes of these genes are homozygous or compound heterozygous mutations. The frequency of PARK2, PINK1 and PARK7 mutations is still under debate, as is the significance and pathogenicity of the single heterozygous mutations/variants, which are also detected among PD patients. The aim of the study was to analyze the incidence of autosomal recessive genes PARK2, PINK1, PARK7 mutations in Polish EO-PD patients.Material and methodsThe analysis of the PARK2, PINK1 and PARK7 genes was performed in a group of 150 Polish EO-PD patients (age of onset < 45 years). Mutation analysis was based on sequencing and gene dosage abnormality identification.ResultsMutations were identified only in the PARK2 and PINK1 genes with the frequency of 4.7% and 2.7% of subjects, respectively. In PARK2, point mutations and exons' rearrangements, and in PINK1 only missense mutations were detected. In both genes mutations were found as compound heterozygous/homozygous and single heterozygous. EO-PD patients’ genotype-phenotype correlation revealed similarities of clinical features in mutation carriers and non-carriers.ConclusionsThe frequency of the PARK2, PINK1, PARK7 mutations among Polish EO-PD patients seems to be low. The role of single heterozygous mutations remains a matter of debate and needs further investigations.     

Evidence for early and progressive ultrasonic vocalization and oromotor deficits in a PINK1 gene knockout rat model of Parkinson's disease

Parkinson's disease (PD) is a progressive neurodegenerative disease that leads to a wide range of motor and nonmotor deficits. Specifically, voice and swallow deficits manifest early, are devastating to quality of life, and are difficult to treat with standard medical therapies. The pathological hallmarks of PD include accumulation of the presynaptic protein α‐synuclein (αSyn) as well as degeneration of substantia nigra dopaminergic neurons. However, there is no clear understanding of how or when this pathology contributes to voice and swallow dysfunction in PD. The present study evaluates the effect of loss of function of the phosphatase and tensin homolog‐induced putative kinase 1 gene in rats (PINK1^–/–), a model of autosomal recessive PD in humans, on vocalization, oromotor and limb function, and neurodegenerative pathologies. Behavioral measures include ultrasonic vocalizations, tongue force, biting, and gross motor performance that are assayed at 2, 4, 6, and 8 months of age. Aggregated αSyn and tyrosine hydroxylase immunoreactivity (TH‐ir) were measured at 8 months. We show that, compared with wild‐type controls, PINK1^–/– rats develop 1) early and progressive vocalization and oromotor deficits, 2) reduced TH‐ir in the locus coeruleus that correlates with vocal loudness and tongue force, and 3) αSyn neuropathology in brain regions important for cranial sensorimotor control. This novel approach of characterizing a PINK1^–/– genetic model of PD provides the foundational work required to define behavioral biomarkers for the development of disease‐modifying therapeutics for PD patients. © 2015 Wiley Periodicals, Inc.     

Familial Parkinsonism with digenic parkin and PINK1 mutations

To clarify the genetic correlation between parkin and PINK1, we screened for PINK1 mutations in 175 parkinsonism patients with parkin mutations. We detected two sibling pairs and one sporadic patient carrying both parkin and PINK1 mutations. The age at onset of Parkinsonism of patients with the digenic mutations was lower than that of patients with the same parkin mutation alone. In addition, two of three patients carrying both parkin and PINK1 mutations had schizophrenia. These findings indicate that PINK1 mutation might modify parkin mutation‐positive Parkinsonism, and PINK1 mutations might be associated withpsychiatric disorders. © 2008 Movement Disorder Society     

Alterations in tyrosine kinase receptor (Trk) expression induced by insulin-like growth factor-1 in cultured dorsal root ganglion neurons

Insulin-like growth factor-1 (IGF-1) is a neurotrophic factor expressed in small dorsal root ganglion (DRG) neurons. IGF-1 promotes neuronal survival by activating its receptor (IGF-1R). Whether IGF-1 and its signaling pathways influence the expression of tyrosine kinase receptors TrkA, TrkB and TrkC in DRG neurons remains unknown. In the present study, primary cultured DRG neurons were used to determine the effects of IGF-1 on TrkA, TrkB and TrkC expression. The involvement of extracellular signal-regulated protein kinase (ERK1/2) and the effects of phosphatidylinositol 3-kinase (PI3K)/Akt signaling pathways on IGF-1 were also evaluated. DRG neurons were cultured for 48 h and then exposed to IGF-1, PD98059 plus IGF-1, LY294002 plus IGF-1, and PD98059 plus LY294002 plus IGF-1 for an additional 24 h. The DRG neurons were continuously exposed to culture medium as a control. All cultures were then processed for detection of mRNA levels of TrkA, TrkB and TrkC using real-time PCR analysis. Protein levels of TrkA, TrkB and TrkC were detected using a Western blot assay. The expression of TrkA, TrkB and TrkC in situ was determined by a fluorescent labeling technique. The levels of phosphorylated ERK1/2 (pERK1/2) and phosphorylated Akt (pAkt) were detected using a Western blot assay. The results indicated that in primary cultured DRG neurons, IGF-1 increased the expression of TrkA and TrkB and their mRNAs but not TrkC or its mRNA. Neither the ERK1/2 inhibitor PD98059 nor the PI3K inhibitor LY294002 alone blocked the effect of IGF-1, but the use of both inhibitors together was effective. IGF-1 may play an important role in regulating the expression of different Trk receptors in DRG neurons through the ERK1/2 and PI3K/Akt signaling pathways. These results suggest that IGF-1 signaling might be a potential target on modifying distinct Trk receptor-mediated biological effects.     

Deficiency of the negative immune regulator B7-H1 enhances inflammation and neuropathic pain after chronic constriction injury of mouse sciatic nerve

Peripheral nerve injury induces a profound local inflammatory response that involves T cells and macrophages and augments the generation of neuropathic pain. The mechanisms underlying immune cell activation or inhibition in the peripheral nervous system, however, are unknown. The co-inhibitory molecule B7-H1 (PD-L1, CD274) attenuates immune cell proliferation and cytokine production and protects from inflammation-induced tissue damage. We analyzed the temporal gene expression profile of B7-H1 and different cytokines after chronic constriction injury (CCI) of the sciatic nerve, a lesion paradigm inducing neuropathic pain, by quantitative real-time polymerase chain reaction and immunohistochemistry in B7-H1^−/− mice and wild-type (WT) controls. B7-H1 mRNA was markedly induced in WT nerves after CCI, and macrophages could be identified as major B7-H1 source. The proinflammatory mediators tumor necrosis factor alpha (TNFα) and monocyte chemoattractant protein-1 (MCP-1) displayed a strong, but transient expression in degenerating nerves on day 1 after CCI in WT mice, while a biphasic expression peak on day 1 and day 28 was found in B7-H1^−/− mice. Overall, TNFα and MCP-1 levels in B7-H1-deficient nerves dramatically exceeded those in WT controls. In contrast, induction of the anti-inflammatory cytokine interleukin(IL)-10 was restricted to WT nerves. The observation that B7-H1 deficiency enhances inflammation upon CCI was further corroborated by immunohistochemistry showing increased numbers of T cells and macrophages in injured nerves from B7-H1^−/− mice. Interestingly, mechanical hyperalgesia was more pronounced in the absence of B7-H1. Our study identifies B7-H1 as an important suppressor of the inflammatory response and neuropathic pain occurring after peripheral nerve injury.     

Inhibition of the mitochondrial calcium uniporter rescues dopaminergic neurons in pink1−/− zebrafish

Mutations in PTEN‐induced putative kinase 1 (PINK1) are a cause of early onset Parkinson's disease (PD). Loss of PINK1 function causes dysregulation of mitochondrial calcium homeostasis, resulting in mitochondrial dysfunction and neuronal cell death. We report that both genetic and pharmacological inactivation of the mitochondrial calcium uniporter (MCU), located in the inner mitochondrial membrane, prevents dopaminergic neuronal cell loss in pink1^Y431* mutant zebrafish (Danio rerio) via rescue of mitochondrial respiratory chain function. In contrast, genetic inactivation of the voltage dependent anion channel 1 (VDAC1), located in the outer mitochondrial membrane, did not rescue dopaminergic neurons in PINK1 deficient D. rerio. Subsequent gene expression studies revealed specific upregulation of the mcu regulator micu1 in pink1^Y431* mutant zebrafish larvae and inactivation of micu1 also results in rescue of dopaminergic neurons. The functional consequences of PINK1 deficiency and modified MCU activity were confirmed using a dynamic in silico model of Ca²⁺ triggered mitochondrial activity. Our data suggest modulation of MCU‐mediated mitochondrial calcium homeostasis as a possible neuroprotective strategy in PINK1 mutant PD.