scholarly journals PINK1 import regulation at a crossroad of mitochondrial fate: the molecular mechanisms of PINK1 import

2019 ◽  
Author(s):  
Shiori Sekine
Keyword(s):  
Health Status ◽  
Ubiquitin Ligase ◽  
Molecular Mechanisms ◽  
Mitochondrial Damage ◽  
Dependent Manner ◽  
Loss Of Function ◽  
Kinase Activation ◽  
Critical Step ◽  
Signalling Cascades ◽  
Stress Dependent

Abstract PTEN-induced kinase 1 (PINK1) is a mitochondrial kinase whose activity is tightly regulated by the mitochondrial health status. In response to mitochondrial damage, activated PINK1 can promote mitophagy, an autophagic elimination of damaged mitochondria, by cooperating with Parkin ubiquitin ligase. Loss-of-function of PINK1/Parkin-mediated mitophagy results in the accumulation of dysfunctional mitochondria, which could be one aetiology of Parkinson’s disease (PD). Within step-by-step signalling cascades of PINK1/Parkin-mediated mitophagy, mitochondrial damage-dependent PINK1 kinase activation is a critical step to trigger the mitophagy signal. Recent investigation of this process reveals that this stress-dependent PINK1 kinase activation is achieved by its regulated import into different mitochondrial compartments. Thus, PINK1 import regulation stands at an important crossroad to determine the mitochondrial fate—‘keep’ or ‘remove’? In this review, we will summarize how the PINK1 import is regulated in a mitochondrial health status-dependent manner and how this process could be pharmacologically modulated to activate the PINK1/Parkin pathway.

scholarly journals Molecular Bases of Human Malformation Syndromes Involving the SHH Pathway: GLIA/R Balance and Cardinal Phenotypes

2021 ◽  
Vol 22 (23) ◽  
pp. 13060
Author(s):  
Yo Niida ◽  
Sumihito Togi ◽  
Hiroki Ura
Keyword(s):  
Molecular Mechanisms ◽  
Brain Size ◽  
Balance Model ◽  
Dependent Manner ◽  
Loss Of Function ◽  
Concentration Dependent Manner ◽  
Shh Pathway ◽  
Embryonic Morphogenesis ◽  
Malformation Syndromes ◽  
Molecular Bases

Human hereditary malformation syndromes are caused by mutations in the genes of the signal transduction molecules involved in fetal development. Among them, the Sonic hedgehog (SHH) signaling pathway is the most important, and many syndromes result from its disruption. In this review, we summarize the molecular mechanisms and role in embryonic morphogenesis of the SHH pathway, then classify the phenotype of each malformation syndrome associated with mutations of major molecules in the pathway. The output of the SHH pathway is shown as GLI activity, which is generated by SHH in a concentration-dependent manner, i.e., the sum of activating form of GLI (GLIA) and repressive form of GLI (GLIR). Which gene is mutated and whether the mutation is loss-of-function or gain-of-function determine in which concentration range of SHH the imbalance occurs. In human malformation syndromes, too much or too little GLI activity produces symmetric phenotypes affecting brain size, craniofacial (midface) dysmorphism, and orientation of polydactyly with respect to the axis of the limb. The symptoms of each syndrome can be explained by the GLIA/R balance model.

Abstract 927: The Role Of Peroxiredoxins As Mechanosensitive Antioxidants In Endothelial Cells

Circulation ◽  
2007 ◽  
Vol 116 (suppl_16) ◽  
Author(s):  
Amy Mowbray ◽  
Sang Won Kang ◽  
Sue Goo Rhee ◽  
Hanjoong Jo
Keyword(s):  
Endothelial Cells ◽  
Shear Stress ◽  
Subcellular Localization ◽  
Molecular Mechanisms ◽  
Immunofluorescent Staining ◽  
Dependent Manner ◽  
Laminar Shear Stress ◽  
Arterial Tree ◽  
Aortic Endothelial Cells ◽  
Stress Dependent

Atherosclerosis is an inflammatory disease occurring primarily in curved or branching regions of the arterial tree where disturbed flow patterns, such as oscillation, exist. We have previously shown that oscillatory shear stress (OS) increases reactive oxygen species (ROS) levels in endothelial cells, while laminar shear stress (LS) reduces ROS compared to static controls. OS stimulation of ROS has been shown to occur in an NADPH oxidase-dependent manner. However, the mechanism by which LS removes ROS remains unclear. Peroxiredoxins (PRX) are a family of antioxidant proteins that have been linked to the prevention of oxidative stress and inflammation, but their role in atherosclerosis is unknown. Here, we hypothesize that shear stress regulates ROS levels in endothelial cells by controlling antioxidant peroxiredoxins. To test this hypothesis, bovine aortic endothelial cells (BAEC) were subjected to static, laminar, and oscillatory fluid flow conditions via cone-and-plate viscometer. Western blot analysis and immunofluorescent staining were used to evaluate the expression and subcellular localization of six known mammalian peroxiredoxins (PRX I-VI). Immunoblots indicated that BAEC express all six isoforms of peroxiredoxin proteins and that LS upregulated PRX I levels significantly compared to static controls and OS. Immunofluorescence also showed a distinct subcellular localization of each PRX: PRX I, II, IV, V and VI in the cytoplasm, PRX I, IV and V in the Golgi, PRX III in the mitochondria, and PRX I in the nucleus. These results indicate that peroxiredoxins are mechanosensitive antioxidants, removing ROS in a subcellular-specific manner. Based on these data, we suggest that peroxiredoxin antioxidants are likely involved in the molecular mechanisms that control shear stress-dependent atherosclerotic plaque development.

scholarly journals c-Jun NH2-terminal Kinase (JNK)-interacting Protein-3 (JIP3) Regulates Neuronal Axon Elongation in a Kinesin- and JNK-dependent Manner

2013 ◽  
Vol 288 (20) ◽  
pp. 14531-14543 ◽  
Author(s):  
Tao Sun ◽  
Nuo Yu ◽  
Lu-Kai Zhai ◽  
Na Li ◽  
Chao Zhang ◽  
...  
Keyword(s):  
Cortical Neurons ◽  
Hippocampal Neurons ◽  
Molecular Mechanisms ◽  
Neuronal Development ◽  
Dependent Manner ◽  
Loss Of Function ◽  
Anterograde Transport ◽  
Interacting Protein ◽  
Axon Elongation

The development of neuronal polarity is essential for the establishment of the accurate patterning of neuronal circuits in the brain. However, little is known about the underlying molecular mechanisms that control rapid axon elongation during neuronal development. Here, we report that c-Jun NH2-terminal kinase (JNK)-interacting protein-3 (JIP3) is highly expressed at axon tips during the critical period for axon development. Using gain- and loss-of-function approaches, immunofluorescence analysis, and in utero electroporation, we find that JIP3 can enhance axon elongation in primary hippocampal neurons and cortical neurons in vivo. We further demonstrate that JIP3 promotes axon elongation in a kinesin- and JNK-dependent manner using several deletion mutants of JIP3. Next, we demonstrate that the successful transportation of JIP3 to axon tips by kinesin is a prerequisite for enhancing JNK phosphorylation in this area and therefore promotes axon elongation, constituting a novel mechanism for coupling JIP3 anterograde transport with JNK signaling at the distal axons and axon elongation. Finally, our immunofluorescence data suggest that the activation of JNK at axon tips facilitates axon elongation by modulating cofilin activity and actin filament dynamics. These findings may have important implications for our understanding of neuronal axon elongation during development.

scholarly journals Zn2+ influx activates ERK and Akt signaling pathways

2021 ◽  
Vol 118 (11) ◽  
pp. e2015786118
Author(s):  
Kelsie J. Anson ◽  
Giulia A. Corbet ◽  
Amy E. Palmer
Keyword(s):  
Signaling Pathways ◽  
Molecular Mechanisms ◽  
Single Cells ◽  
Cell Types ◽  
Cell Physiology ◽  
Kinase Signaling ◽  
Experimental Conditions ◽  
Kinase Activation ◽  
Fluorescent Biosensors ◽  
Stress Dependent

Zinc (Zn2+) is an essential metal in biology, and its bioavailability is highly regulated. Many cell types exhibit fluctuations in Zn2+ that appear to play an important role in cellular function. However, the detailed molecular mechanisms by which Zn2+ dynamics influence cell physiology remain enigmatic. Here, we use a combination of fluorescent biosensors and cell perturbations to define how changes in intracellular Zn2+ impact kinase signaling pathways. By simultaneously monitoring Zn2+ dynamics and kinase activity in individual cells, we quantify changes in labile Zn2+ and directly correlate changes in Zn2+ with ERK and Akt activity. Under our experimental conditions, Zn2+ fluctuations are not toxic and do not activate stress-dependent kinase signaling. We demonstrate that while Zn2+ can nonspecifically inhibit phosphatases leading to sustained kinase activation, ERK and Akt are predominantly activated via upstream signaling and through a common node via Ras. We provide a framework for quantification of Zn2+ fluctuations and correlate these fluctuations with signaling events in single cells to shed light on the role that Zn2+ dynamics play in healthy cell signaling.

scholarly journals Nogo-A Modulates the Synaptic Excitation of Hippocampal Neurons in a Ca2+-Dependent Manner

Cells ◽  
2021 ◽  
Vol 10 (9) ◽  
pp. 2299
Author(s):  
Kristin Metzdorf ◽  
Steffen Fricke ◽  
Maria Teresa Balia ◽  
Martin Korte ◽  
Marta Zagrebelsky
Keyword(s):  
Synaptic Plasticity ◽  
Hippocampal Neurons ◽  
Molecular Mechanisms ◽  
Growth Inhibitor ◽  
Neurite Growth ◽  
Excitatory Synapses ◽  
Dependent Manner ◽  
Loss Of Function ◽  
Synaptic Excitation ◽  
Primary Mouse

A tight regulation of the balance between inhibitory and excitatory synaptic transmission is a prerequisite for synaptic plasticity in neuronal networks. In this context, the neurite growth inhibitor membrane protein Nogo-A modulates synaptic plasticity, strength, and neurotransmitter receptor dynamics. However, the molecular mechanisms underlying these actions are unknown. We show that Nogo-A loss-of-function in primary mouse hippocampal cultures by application of a function-blocking antibody leads to higher excitation following a decrease in GABAARs at inhibitory and an increase in the GluA1, but not GluA2 AMPAR subunit at excitatory synapses. This unbalanced regulation of AMPAR subunits results in the incorporation of Ca2+-permeable GluA2-lacking AMPARs and increased intracellular Ca2+ levels due to a higher Ca2+ influx without affecting its release from the internal stores. Increased neuronal activation upon Nogo-A loss-of-function prompts the phosphorylation of the transcription factor CREB and the expression of c-Fos. These results contribute to the understanding of the molecular mechanisms underlying the regulation of the excitation/inhibition balance and thereby of plasticity in the brain.

scholarly journals Cylindromatosis Drives Synapse Pruning and Weakening by Promoting Macroautophagy through Akt-mTOR Signaling

2021 ◽  
Author(s):  
Wei-Dong Yao ◽  
Alexis S Zajicek ◽  
Huihui Dai ◽  
Mary Catherine Skolfield ◽  
Hannah L Phillips ◽  
...  
Keyword(s):  
Molecular Mechanisms ◽  
Mtor Signaling ◽  
Mammalian Brain ◽  
Autophagic Flux ◽  
Dependent Manner ◽  
Synapse Elimination ◽  
Loss Of Function ◽  
Synapse Maintenance ◽  
Behavioral Impairments

The lysine-63 deubiquitinase cylindromatosis (CYLD) is long recognized as a tumor suppressor in immunity and inflammation and its loss-of-function mutations lead to familial cylindromatosis. However, recent studies reveal that CYLD is enriched in mammalian brain postsynaptic densities, and a gain-of-function mutation causes frontotemporal dementia (FTD), suggesting critical roles at excitatory synapses. Here we report that CYLD drives synapse elimination and weakening by acting on the Akt-mTOR-autophagy axis. Mice lacking CYLD display abnormal sociability, anxiety- and depression-like behaviors, and cognitive inflexibility. These behavioral impairments are accompanied by excessive synapse numbers, increased postsynaptic efficacy, augmented synaptic summation, and impaired NMDA receptor-dependent hippocampal long-term depression (LTD). Exogenous expression of CYLD results in removal of established dendritic spines from mature neurons in a deubiquitinase activity-dependent manner. In search of underlying molecular mechanisms, we find that CYLD knockout mice display marked overactivation of Akt and mTOR and reduced autophagic flux and, conversely, CYLD overexpression potently suppresses Akt and mTOR activity and promotes autophagy. Consequently, abrogating the Akt-mTOR-autophagy signaling pathway abolishes CYLD-induced spine loss, whereas enhancing autophagy in vivo by the mTOR inhibitor rapamycin rescues the synaptic pruning and LTD deficits in mutant mice. Our findings establish CYLD, via Akt-mTOR signaling, as a synaptic autophagy activator that exerts critical modulations on synapse maintenance, function, and plasticity.

scholarly journals Lafora Disease: A Review of Molecular Mechanisms and Pathology

2018 ◽  
Vol 49 (06) ◽  
pp. 357-362 ◽  
Author(s):  
Brandy Verhalen ◽  
Susan Arnold ◽  
Berge Minassian
Keyword(s):  
Ubiquitin Ligase ◽  
Molecular Mechanisms ◽  
Neurodegenerative Disorder ◽  
Vegetative State ◽  
Glycogen Synthesis ◽  
Loss Of Function ◽  
Lafora Disease ◽  
Lafora Bodies ◽  
Progressive Myoclonus Epilepsy ◽  
Myoclonus Epilepsy

AbstractLafora's disease is a neurodegenerative disorder caused by recessive loss-of-function mutations in the EPM2A (laforin glycogen phosphatase) or EPM2B (malin E3 ubiquitin ligase) genes. Neuropathology is characterized by malformed precipitated glycogen aggregates termed Lafora bodies. Asymptomatic until adolescence, patients undergo first insidious then rapid progressive myoclonus epilepsy toward a vegetative state and death within a decade. Laforin and malin interact to regulate glycogen phosphorylation and chain length pattern, the latter critical to glycogen's solubility. Significant gaps remain in precise mechanistic understanding. However, demonstration that partial reduction in brain glycogen synthesis near-completely prevents the disease in its genetic animal models opens a direct present path to therapy.

Isolation of Membrane-enriched fractions from mouse cortical neurons v1

2021 ◽  
Author(s):  
Odetta Antico ◽  
Erica Barini ◽  
Miratul M. K. Muqit
Keyword(s):  
Ubiquitin Ligase ◽  
Cortical Neurons ◽  
Spatial Configuration ◽  
Mitochondrial Damage ◽  
Cellular Proteins ◽  
Neuronal Cultures ◽  
Dependent Manner ◽  
Primary Cells ◽  
Post Translational Modifications ◽  
Molecular Events

Upon mitochondrial damage, activation of the PINK1 kinase and Parkin ubiquitin ligase induces ubiquitylation of multiple proteins at the mitochondria to stimulate their elimination by mitophagy. Protein ubiquitylation is a highly dynamic, reversible and complex post-translation modification (PTM) and it is frequently linked with phosphorylation. The major challenges, for biochemical and quantitative proteomic analysis of cellular proteins that are ubiquitylated and phosphorylated in response to mitochondrial damage in a PINK1-Parkin-dependent manner, involve the spatial configuration and stoichiometry of these post-translational modifications occurring on the mitochondria. Here, we describe an optimised protocol to isolate membrane-enriched fractions that provides high mitochondrial yield from primary cells, such as neuronal cultures. This protocol, in combination with other enrichment strategies, will facilitate proteomic and biochemical workflows for investigation of molecular events defined by PINK1/Parkin pathway.

scholarly journals The ubiquitin ligase Ariadne-1 regulates NSF for neurotransmitter release

2020 ◽  
Author(s):  
Juanma Ramírez ◽  
Miguel Morales ◽  
Nerea Osinalde ◽  
Imanol Martínez-Padrón ◽  
Ugo Mayor ◽  
...  
Keyword(s):  
Ubiquitin Ligase ◽  
Neurotransmitter Release ◽  
Quantitative Proteomics ◽  
Dependent Manner ◽  
Loss Of Function ◽  
Sensitive Factor ◽  
Active Zones ◽  
Protein Ensembles ◽  
Mutant Phenotypes

ABSTRACTAriadne-1 (Ari-1) is an essential E3 ubiquitin-ligase whose neuronal substrates are yet to be identified. We have used an in vivo ubiquitin biotinylation strategy coupled to quantitative proteomics to identify putative Ari-1 substrates in Drosophila heads. Sixteen candidates met the established criteria. Amongst those, we identified Comatose (Comt), the homologue of the N-ethylmaleimide sensitive factor (NSF). Using an in vivo GFP pulldown approach, we validate Comt/NSF to be an ubiquitination substrate of Ari-1 in fly neurons. The interaction results in the monoubiquitination of Comt/NSF. We also report that Ari-1 loss of function mutants display a lower rate of spontaneous neurotransmitter release due to failures at the pre-synaptic side. By contrast, evoked release in Ari-1 mutants is enhanced in a Ca2+ dependent manner without modifications in the number of active zones, indicating that the probability of release per synapse is increased in these mutants. The distinct Ari-1 mutant phenotypes in spontaneous versus evoked release indicate that NSF activity discriminates the two corresponding protein ensembles that mediate each mode of release. Our results, thus, provide a mechanism to regulate NSF activity in the synapse through Ari-1-dependent ubiquitination.

scholarly journals A balance of FGF and BMP signals regulates cell cycle exit and Equarin expression in lens cells

2012 ◽  
Vol 23 (16) ◽  
pp. 3266-3274 ◽  
Author(s):  
Miguel Jarrin ◽  
Tanushree Pandit ◽  
Lena Gunhaga
Keyword(s):  
Cell Cycle ◽  
Molecular Mechanisms ◽  
Dependent Manner ◽  
Lens Fiber ◽  
Cell Cycle Exit ◽  
Loss Of Function ◽  
Fiber Cells ◽  
Morphogenetic Protein ◽  
Lens Cells ◽  
Chick Lens

In embryonic and adult lenses, a balance of cell proliferation, cell cycle exit, and differentiation is necessary to maintain physical function. The molecular mechanisms regulating the transition of proliferating lens epithelial cells to differentiated primary lens fiber cells are poorly characterized. To investigate this question, we used gain- and loss-of-function analyses to modulate fibroblast growth factor (FGF) and/or bone morphogenetic protein (BMP) signals in chick lens/retina explants. Here we show that FGF activity plays a key role for proliferation independent of BMP signals. Moreover, a balance of FGF and BMP signals regulates cell cycle exit and the expression of Ccdc80 (also called Equarin), which is expressed at sites where differentiation of lens fiber cells occurs. BMP activity promotes cell cycle exit and induces Equarin expression in an FGF-dependent manner. In contrast, FGF activity is required but not sufficient to induce cell cycle exit or Equarin expression. Furthermore, our results show that in the absence of BMP activity, lens cells have increased cell cycle length or are arrested in the cell cycle, which leads to decreased cell cycle exit. Taken together, these findings suggest that proliferation, cell cycle exit, and early differentiation of primary lens fiber cells are regulated by counterbalancing BMP and FGF signals.

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