Loss of PTEN-Induced Kinase 1 Regulates Oncogenic Ras-Driven Tumor Growth By Inhibiting Mitochondrial Fission.

Mitochondrial metabolism and dynamics (fission and fusion) critically regulate cell survival and proliferation, and abnormalities in these pathways are implicated in both neurodegenerative disorders and cancer. Mitochondrial fission is necessary for the growth of mutant Ras-dependent tumors. Here, we investigated whether loss of PTEN-induced kinase 1 (PINK1) - a mitochondrial kinase linked to recessive familial Parkinsonism - affects the growth of oncogenic Ras-induced tumor growth and .

Mitochondrial and Autophagic Regulation of Adult Neurogenesis in the Healthy and Diseased Brain.

Adult neurogenesis is a highly regulated process during which new neurons are generated from neural stem cells in two discrete regions of the adult brain: the subventricular zone of the lateral ventricle and the subgranular zone of the dentate gyrus in the hippocampus. Defects of adult hippocampal neurogenesis have been linked to cognitive decline and dysfunction during natural aging and in neurodegenerative diseases, as well as psychological stress-induced mood disorders. Understanding the mechanisms and pathways that regulate adult neurogenesis is crucial to improving preventative measures and therapies for these conditions.

Proteasome inhibition promotes mono-ubiquitination and nuclear translocation of mature (52 kDa) PINK1.

Mutations of PTEN-induced kinase 1 (PINK1) cause recessive familial Parkinson's disease. Cells lacking PINK1 display mitochondrial deficits and increased sensitivity to oxidative and proteasomal stress. It has been shown that the 52-kDa (mature) form of PINK1 in the cytoplasm mitigates proteasomal stress-induced cell death by enhancing aggresomes formation and autophagy.

PINK1 deficiency is associated with increased deficits of adult hippocampal neurogenesis and lowers the threshold for stress-induced depression in mice.

Parkinson's disease (PD) is characterized by motor impairments and several non-motor features, including frequent depression and anxiety. Stress-induced deficits of adult hippocampal neurogenesis (AHN) have been linked with abnormal affective behavior in animals. It has been speculated that AHN defects may contribute to affective symptoms in PD, but this hypothesis remains insufficiently tested in animal models.

Lack of PINK1 alters glia innate immune responses and enhances inflammation-induced, nitric oxide-mediated neuron death.

Neuroinflammation is involved in the pathogenesis of Parkinson's disease (PD) and other neurodegenerative disorders. We show that lack of PINK1- a mitochondrial kinase linked to recessive familial PD - leads to glia type-specific abnormalities of innate immunity. PINK1 loss enhances LPS/IFN-γ stimulated pro-inflammatory phenotypes of mixed astrocytes/microglia (increased iNOS, nitric oxide and COX-2, reduced IL-10) and pure astrocytes (increased iNOS, nitric oxide, TNF-α and IL-1β), while attenuating expression of both pro-inflammatory (TNF-α, IL-1β) and anti-inflammatory (IL-10) cytokines in microglia.

Loss of PINK1 leads to metabolic deficits in adult neural stem cells and impedes differentiation of newborn neurons in the mouse hippocampus.

Emerging evidence suggests that mitochondrial dynamics regulates adult hippocampal neurogenesis (AHN). Although abnormal AHN has been linked to depression, anxiety, and cognitive dysfunction, which are features of neurodegenerative conditions, including Parkinson's disease (PD), the impact of mitochondrial deficits on AHN have not been explored previously in a model of neurodegeneration. Here, we used PTEN-induced kinase 1-deficient ( ) mice that lacked a mitochondrial kinase mutated in recessive familial PD.

Quantitative expression proteomics and phosphoproteomics profile of brain from PINK1 knockout mice: insights into mechanisms of familial Parkinson's disease.

Parkinson's disease (PD) is an age-related, neurodegenerative motor disorder characterized by progressive degeneration of dopaminergic neurons in the substantia nigra pars compacta and presence of α-synuclein-containing protein aggregates. Mutations in the mitochondrial Ser/Thr kinase PTEN-induced kinase 1 (PINK1) are associated with an autosomal recessive familial form of early-onset PD. Recent studies have suggested that PINK1 plays important neuroprotective roles against mitochondrial dysfunction by phosphorylating and recruiting Parkin, a cytosolic E3 ubiquitin ligase, to facilitate elimination of damaged mitochondria via autophagy-lysosomal pathways.

The use of an adeno-associated viral vector for efficient bicistronic expression of two genes in the central nervous system.

Recombinant adeno-associated viral (AAV) vectors are one of the most promising therapeutic delivery systems for gene therapy to the central nervous system (CNS). Preclinical testing of novel gene therapies requires the careful design and production of AAV vectors and their successful application in a model of CNS injury. One major limitation of AAV vectors is their limited packaging capacity (<5 kb) making the co-expression of two genes (e.

Unaltered striatal dopamine release levels in young Parkin knockout, Pink1 knockout, DJ-1 knockout and LRRK2 R1441G transgenic mice.

Parkinson's disease (PD) is one of the most prevalent neurodegenerative brain diseases; it is accompanied by extensive loss of dopamine (DA) neurons of the substantia nigra that project to the putamen, leading to impaired motor functions. Several genes have been associated with hereditary forms of the disease and transgenic mice have been developed by a number of groups to produce animal models of PD and to explore the basic functions of these genes. Surprisingly, most of the various mouse lines generated such as Parkin KO, Pink1 KO, DJ-1 KO and LRRK2 transgenic have been reported to lack degeneration of nigral DA neuron, one of the hallmarks of PD.

Mitochondrial and cytosolic roles of PINK1 shape induced regulatory T-cell development and function.

Mutations in PTEN-induced kinase 1 (PINK1), a serine/threonine kinase linked to familial early-onset Parkinsonism, compromise mitochondrial integrity and metabolism and impair AKT signaling. As the activation of a naïve T cell requires an AKT-dependent reorganization of a cell's metabolic machinery, we sought to determine if PINK1-deficient T cells lack the ability to undergo activation and differentiation. We show that CD4(+) T cells from PINK1 knockout mice fail to properly phosphorylate AKT upon activation, resulting in reduced expression of the IL-2 receptor subunit CD25.

Metabolic stress modulates Alzheimer's β-secretase gene transcription via SIRT1-PPARγ-PGC-1 in neurons.

Classic cardio-metabolic risk factors such as hypertension, stroke, diabetes, and hypercholesterolemia all increase the risk of Alzheimer's disease. We found increased transcription of β-secretase/BACE1, the rate-limiting enzyme for Aβ generation, in eNOS-deficient mouse brains and after feeding mice a high-fat, high-cholesterol diet. Up- or downregulation of PGC-1α reciprocally regulated BACE1 in vitro and in vivo.

Shared and cell type-specific mitochondrial defects and metabolic adaptations in primary cells from PINK1-deficient mice.

Background: Mutations in PTEN-induced kinase 1 (PINK1) cause early-onset recessive parkinsonism. PINK1 and Parkin regulate mitochondrial quality control. However, PINK1 ablation in Drosophila and cultured mammalian cell lines affected mitochondrial function/dynamics in opposite ways, confounding the elucidation of the role of PINK1 in these processes.

PINK1 enhances insulin-like growth factor-1-dependent Akt signaling and protection against apoptosis.

Mutations in the PARK6 gene coding for PTEN-induced kinase 1 (PINK1) cause recessive early-onset Parkinsonism. Although PINK1 and Parkin promote the degradation of depolarized mitochondria in cultured cells, little is known about changes in signaling pathways that may additionally contribute to dopamine neuron loss in recessive Parkinsonism. Accumulating evidence implicates impaired Akt cell survival signaling in sporadic and familial PD (PD).

Increased mitochondrial calcium sensitivity and abnormal expression of innate immunity genes precede dopaminergic defects in Pink1-deficient mice.

Background: PTEN-induced kinase 1 (PINK1) is linked to recessive Parkinsonism (EOPD). Pink1 deletion results in impaired dopamine (DA) release and decreased mitochondrial respiration in the striatum of mice. To reveal additional mechanisms of Pink1-related dopaminergic dysfunction, we studied Ca²+ vulnerability of purified brain mitochondria, DA levels and metabolism and whether signaling pathways implicated in Parkinson's disease (PD) display altered activity in the nigrostriatal system of Pink1⁻/⁻ mice.

Extended lifespan of Drosophila parkin mutants through sequestration of redox-active metals and enhancement of anti-oxidative pathways.

The mechanisms underlying neuron death in Parkinson's disease are unknown, but both genetic defects and environmental factors are implicated in its pathogenesis. Mutations in the parkin gene lead to autosomal recessive juvenile Parkinsonism (AR-JP). Here we report that compared to control flies, Drosophila lacking parkin show significantly reduced lifespan but no difference in dopamine neuron numbers when raised on food supplemented with environmental pesticides or mitochondrial toxins.

Mitochondrial dynamics, cell death and the pathogenesis of Parkinson's disease.

The structure and function of the mitochondrial network is regulated by mitochondrial biogenesis, fission, fusion, transport and degradation. A well-maintained balance of these processes (mitochondrial dynamics) is essential for neuronal signaling, plasticity and transmitter release. Core proteins of the mitochondrial dynamics machinery play important roles in the regulation of apoptosis, and mutations or abnormal expression of these factors are associated with inherited and age-dependent neurodegenerative disorders.

Differential sensitivity of the inner ear sensory cell populations to forced cell cycle re-entry and p53 induction.

Previous studies have shown that the maintenance of post-mitotic state is critical for the life-long survival of the inner ear mechanosensory cells, the hair cells. A general concept is that differentiated, post-mitotic cells rapidly die following cell cycle re-entry. Here we have compared the response of postnatal cochlear (auditory) and utricular (balance) hair cells to forced cell cycle reactivation and p53 up-regulation.

Impaired mitochondrial dynamics and function in the pathogenesis of Parkinson's disease.

Parkinson's disease (PD), the most frequent movement disorder, is caused by the progressive loss of the dopamine neurons within the substantia nigra pars compacta (SNc) and the associated deficiency of the neurotransmitter dopamine in the striatum. Most cases of PD occur sporadically with unknown cause, but mutations in several genes have been linked to genetic forms of PD (alpha-synuclein, Parkin, DJ-1, PINK1, and LRRK2). These genes have provided exciting new avenues to study PD pathogenesis and the mechanisms underlying the selective dopaminergic neuron death in PD.

Bidirectional changes in water-maze learning following recombinant adenovirus-associated viral vector (rAAV)-mediated brain-derived neurotrophic factor expression in the rat hippocampus.

Alterations in hippocampal brain-derived neurotrophic factor (BDNF) expression have been implicated in the pathogenesis of emotional and cognitive dysfunction. Here, we induced BDNF overexpression in the rat hippocampus using recombinant adenovirus-associated viral (rAAV) vectors, and studied its long-term (2 months postinduction) effects on anxiety-related behaviour, exploration in the open field, and spatial learning in the water maze. Although the treatment successfully led to substantial elevation of hippocampal BDNF levels, its effect on spatial learning was bidirectional: a subset of rAAV-induced BDNF-overexpressing rats performed well above control level, whereas the rest were clearly impaired.

DJ-1 and Parkin modulate dopamine-dependent behavior and inhibit MPTP-induced nigral dopamine neuron loss in mice.

Parkin-deficient animals exhibit mitochondrial degeneration and increased oxidative stress vulnerability, and both mice and flies lacking DJ-1 are hypersensitive to environmental toxins associated with Parkinson's disease (PD). We used recombinant adeno-associated virus (AAV) gene transfer to study the influence of DJ-1 and Parkin on the dopaminergic system of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-treated mice, a model for sporadic PD. After MPTP lesioning, significantly more dopamine neurons survived in the virus-injected substantia nigra of the AAV-DJ-1 and AAV-Parkin mice when compared with AAV-enhanced green fluorescent protein injected controls.

Hsp70 gene transfer by adeno-associated virus inhibits MPTP-induced nigrostriatal degeneration in the mouse model of Parkinson disease.

Mitochondrial dysfunction and oxidative stress have been implicated in Parkinson disease (PD). In addition, genetic evidence points to an important role of protein misfolding, aggregation, and failure in the proteasomal degradation of specific neuronal proteins in the pathogenesis of PD. The chaperone heat-shock protein 70 (Hsp70) reduces protein misfolding and aggregation and protects cells against a variety of adverse conditions, including oxidative stress.

Transduction profiles of recombinant adeno-associated virus vectors derived from serotypes 2 and 5 in the nigrostriatal system of rats.

We compared the transduction efficiencies and tropisms of titer-matched recombinant adeno-associated viruses (rAAV) derived from serotypes 2 and 5 (rAAV-2 and rAAV-5, respectively) within the rat nigrostriatal system. The two serotypes (expressing enhanced green fluorescent protein [EGFP]) were delivered by stereotaxic surgery into the same animals but different hemispheres of the striatum (STR), the substantia nigra (SN), or the medial forebrain bundle (MFB). While both serotypes transduced neurons effectively within the STR, rAAV-5 resulted in a much larger EGFP-expressing area than did rAAV-2.

Gene transfer into rabbit arteries with adeno-associated virus and adenovirus vectors.

Background: Gene transfer offers considerable potential for altering vessel wall physiology and intervention in vascular disease. Therefore, there is great interest in developing optimal strategies and vectors for efficient, targeted gene delivery into a vessel wall.

Methods: We studied adeno-associated viruses (AAV; 9 x 10(8) to 4 x 10(9) TU/ml) for their usefulness to transduce rabbit arteries in vivo in comparison with adenoviruses (Adv; 1 x 10(9) to 1 x 10(10) pfu/ml).