Project description:The maintenance of mitochondrial homeostasis requires PTEN-induced kinase 1 (PINK1)-dependent mitophagy, and mutations in PINK1 are associated with Parkinson's disease (PD). PINK1 is also downregulated in tumor cells with PTEN mutations. However, there is limited information concerning the role of PINK1 in tissue growth and tumorigenesis. Here, we show that loss of pink1 caused multiple growth defects independent of its pathological target, Parkin. Moreover, knocking-down pink1 in muscle cells induced hyperglycemia and limited systemic organismal growth by induction of Imaginal morphogenesis protein-Late 2 (ImpL2). Similarly, disrupting PTEN activity in multiple tissues impaired systemic growth by reducing pink1 expression, resembling wasting-like syndrome in cancer patients. Furthermore, re-expression of PINK1 fully rescued defects in carbohydrate metabolism and systemic growth induced by the tissue-specific pten mutations. Our data suggest a new function for PINK1 in regulating systemic growth in Drosophila, and shed light on its role in wasting in context of PTEN mutations.
Project description:PTEN-induced kinase 1 (PINK1) is a very short-lived protein that is required for the removal of damaged mitochondria through Parkin translocation and mitophagy. Because the short half-life of PINK1 limits its ability to be trafficked into neurites, local translation is required for this mitophagy pathway to be active far from the soma. The Pink1 transcript is associated with and cotransported with neuronal mitochondria. In concert with translation, the mitochondrial outer membrane protein Synaptojanin 2 Binding Protein (SYNJ2BP) and Synaptojanin 2 (SYNJ2) are required for tethering Pink1 mRNA to mitochondria via an RNA-binding domain in SYNJ2. This neuron-specific adaptation for local translation of PINK1 provides distal mitochondria with a continuous supply of PINK1 for activation of mitophagy.
Project description:Loss of function in the PTEN-induced kinase 1 gene (Pink1) causes an early-onset, autosomal recessive form of PD. The translational Pink1-/- rat shows cranial sensorimotor deficits including: declines in ultrasonic vocalization, negative impacts on social vocal function, and alterations to thyroarytenoid muscle structure. The aim of this study was to identify differentially expressed genes using RNA-sequencing and bioinformatic analysis of the thyroarytenoid muscle of male Pink1-/- rats compared to wildtype controls. To construct gene co-expression networks and gene modules, a WGCNA was used to identify biological networks of interest including where Pink1 was a central node with interconnecting genes. Data are congruent with previous findings demonstrating changes to thyroarytenoid muscle structure. These data are consistent with the hypothesis that differences in peripheral biology may influence the early pathogenesis of vocalizations at the level of the thyroarytenoid muscle.
Project description:Th17-related genes increased in T cells from PINK1-deficient mice. Th17 and Treg cells were increased and decreased in PINK1-deficient cells, respectively, and phosphorylation of signal transducer and activator of transcription 3 (STAT3) was increased in PINK1-deficient cells.
Project description:The PTEN tumor suppressor controls cell death and survival by regulating functions of various molecular targets. Whilst the role of PTEN lipid-phosphatase activity on PtdIns(3,4,5)P3 and inhibition of PI3K pathway is well characterized, the biological relevance of PTEN protein-phosphatase activity remains undefined. Using knock-in (KI) mice harbouring cancer-associated and functionally relevant missense mutations, we show that although loss of PTEN lipid-phosphatase function cooperates with oncogenic PI3K to promote rapid mammary tumorigenesis, the additional loss of PTEN protein-phosphatase activity triggered an extensive cell death response evident in early and advanced mammary tumors. Omics and drug-targeting studies revealed that PI3Ks act to reduce glucocorticoid receptor (GR) levels, which are rescued by loss of PTEN protein-phosphatase activity to restrain cell survival. The dual regulation of GR by PI3K and PTEN functions as a rheostat that can be exploited for the treatment of PTEN-loss driven cancers.
Project description:Parkinson's disease (PD) is an adult-onset movement disorder of largely unknown etiology. We have previously shown that loss-of-function mutations of the mitochondrial protein kinase PINK1 (PTEN induced putative kinase 1) cause the recessive PARK6 variant of PD. Now we generated a PINK1 deficient mouse and observed several novel phenotypes: A progressive reduction of weight and of locomotor activity selectively for spontaneous movements occurred at old age. As in PD, abnormal dopamine levels in the aged nigrostriatal projection accompanied the reduced movements. Possibly in line with the PARK6 syndrome but in contrast to sporadic PD, a reduced lifespan, dysfunction of brainstem and sympathetic nerves, visible aggregates of M-NM-1-synuclein within Lewy bodies or nigrostriatal neurodegeneration were not present in aged PINK1-deficient mice. However, we demonstrate PINK1 mutant mice to exhibit a progressive reduction in mitochondrial preprotein import correlating with defects of core mitochondrial functions like ATP-generation and respiration. In contrast to the strong effect of PINK1 on mitochondrial dynamics in Drosophila melanogaster and in spite of reduced expression of fission factor Mtp18, we show reduced fission and increased aggregation of mitochondria only under stress in PINK1-deficient mouse neurons. Thus, aging Pink1M-bM-^HM-^R/M-bM-^HM-^R mice show increasing mitochondrial dysfunction resulting in impaired neural activity similar to PD, in absence of overt neuronal death. Transcriptome microarray data of Pink1-/- mouse brains in absence of a stressor, even at old age, show remarkably sparse dysregulations. See Gispert-S et al 2009 PLOS ONE. Factorial design comparing Pink1 knock-out mice with wild type littermates in three different tissues (striatum, midbrain, cerebellum at four different timepoints (6, 12, 14 weeks, and 18 month)
Project description:Parkinson's disease (PD) is an adult-onset movement disorder of largely unknown etiology. We have previously shown that loss-of-function mutations of the mitochondrial protein kinase PINK1 (PTEN induced putative kinase 1) cause the recessive PARK6 variant of PD. Now we generated a PINK1 deficient mouse and observed several novel phenotypes: A progressive reduction of weight and of locomotor activity selectively for spontaneous movements occurred at old age. As in PD, abnormal dopamine levels in the aged nigrostriatal projection accompanied the reduced movements. Possibly in line with the PARK6 syndrome but in contrast to sporadic PD, a reduced lifespan, dysfunction of brainstem and sympathetic nerves, visible aggregates of α-synuclein within Lewy bodies or nigrostriatal neurodegeneration were not present in aged PINK1-deficient mice. However, we demonstrate PINK1 mutant mice to exhibit a progressive reduction in mitochondrial preprotein import correlating with defects of core mitochondrial functions like ATP-generation and respiration. In contrast to the strong effect of PINK1 on mitochondrial dynamics in Drosophila melanogaster and in spite of reduced expression of fission factor Mtp18, we show reduced fission and increased aggregation of mitochondria only under stress in PINK1-deficient mouse neurons. Thus, aging Pink1−/− mice show increasing mitochondrial dysfunction resulting in impaired neural activity similar to PD, in absence of overt neuronal death. Transcriptome microarray data of Pink1-/- mouse brains in absence of a stressor, even at old age, show remarkably sparse dysregulations. See Gispert-S et al 2009 PLOS ONE.
Project description:Mitochondrial quality control failure is frequently observed in neurodegenerative diseases. The detection of damaged mitochondria by stabilization of PTEN-induced kinase 1 (PINK1) requires transport of Pink1 mRNA by tethering it to the mitochondrial surface. Here, we report that inhibition of AMPK by activation of the insulin signaling cascade prevents Pink1 mRNA binding to mitochondria. Mechanistically, AMPK phosphorylates the RNA anchor complex subunit SYNJ2BP within its PDZ domain, a phosphorylation site that is necessary for its interaction with the RNA-binding protein SYNJ2. Interestingly, loss of mitochondrial Pink1 mRNA association upon insulin addition is required for PINK1 protein activation and its function as a ubiquitin kinase in the mitophagy pathway, thus placing PINK1 function under metabolic control. Induction of insulin-resistance in vitro by the key genetic Alzheimer-risk factor apolipoprotein E4 retains Pink1 mRNA at the mitochondria and prevents proper PINK1 activity especially in neurites. Our results thus identify a metabolic switch controlling Pink1 mRNA localization and PINK1 activity via insulin and AMPK signaling in neurons and propose a mechanistic connection between insulin resistance and mitochondrial dysfunction.
Project description:Mutations in PTEN-induced putative kinase 1 (PINK1) cause autosomal recessive early onset Parkinson disease (PD). PINK1 is a Ser/Thr kinase that regulates mitochondrial quality control by triggering mitophagy mediated by the ubiquitin ligase Parkin. Upon mitochondrial damage, PINK1 accumulates on the outer mitochondrial membrane (OMM) forming a high molecular weight complex with the translocase of the outer membrane (TOM). PINK1 then phosphorylates ubiquitin, which enables recruitment and activation of Parkin followed by autophagic clearance of the damaged mitochondrion. Thus, Parkin-dependent mitophagy hinges on the stable accumulation of PINK1 on the TOM complex. Yet, the mechanism linking mitochondrial stressors to PINK1 accumulation and whether the translocases of the inner membrane (TIMs) are also involved, remain unclear. Herein, we demonstrate that mitochondrial stress induces the formation of a PINK1-TOM-TIM23 supercomplex in human cultured cell lines, dopamine neurons, and midbrain organoids. Moreover, we show that PINK1 is required to stably tether the TOM to TIM23 complexes in response to stress, such that the supercomplex fails to accumulate in cells lacking PINK1. This tethering is dependent on an interaction between the PINK1 NT-CTE module and the cytosolic domain of the Tom20 subunit of the TOM complex, the disruption of which, by either designer or PD-associated PINK1 mutations, inhibits downstream mitophagy. Together, the findings provide key insight into how PINK1 interfaces with the mitochondrial import machinery, with important implications for the mechanisms of mitochondrial quality control and PD pathogenesis.
Project description:The PTEN:P-Rex2 complex is a commonly mutated signaling nodes in metastatic cancer. The dual-specificity phosphatase PTEN canonically functions as a tumour suppressor by hydrolysing PI(3,4,5)P3 to PI(4,5)P2 to inhibit PI3K-AKT signaling. P-Rex2 is a RhoGTPase guanine nucleotide exchange factor activated by both Gβγ and PI(3,4,5)P3 downstream of G protein-coupled receptor and receptor tyrosine kinase signaling. Assembly of the PTEN:P-Rex2 complex inhibits the activity of both proteins, and its dysregulation can drive PI3K-AKT signaling and cell proliferation. However, structural insights into both PTEN:P-Rex2 complex assembly and its dysregulation by cancer-associated mutations remain limited. Here, using crosslinking mass spectrometry and functional studies, we provide mechanistic insights into PTEN:P-Rex2 complex assembly and co-inhibition. PTEN is anchored to P-Rex2 by interactions between the PTEN C-terminal tail PDZ-interacting motif and the second PDZ domain of P-Rex2. This interaction bridges PTEN across the P-Rex2 surface, occluding PI(3,4,5)P3 hydrolysis. Conversely, PTEN both allosterically promotes an autoinhibited P-Rex2 conformation and occludes Gβγ binding. These insights allow us to define a new gain-of-function class of cancer mutations within the PTEN:P-Rex2 interface that uncouples PTEN inhibition of Rac1 signaling. In addition, we observe synergy between PTEN deactivating and P-Rex2 truncation mutations that combine to drive Rac1 activation to a greater extent than either single mutation alone.