RESUMO
Activating mutations in leucine-rich repeat kinase 2 (LRRK2) represent the most common cause of monogenic Parkinson's disease. LRRK2 is a large multidomain protein kinase that phosphorylates a specific subset of the â¼65 human Rab GTPases, which are master regulators of the secretory and endocytic pathways. After phosphorylation by LRRK2, Rabs lose the capacity to bind cognate effector proteins and guanine nucleotide exchange factors. Moreover, the phosphorylated Rabs cannot interact with their cognate prenyl-binding retrieval proteins (also known as guanine nucleotide dissociation inhibitors) and, thus, they become trapped on membrane surfaces. Instead, they gain the capacity to bind phospho-Rab-specific effector proteins, such as RILPL1, with resulting pathological consequences. Rab proteins also act upstream of LRRK2 by controlling its activation and recruitment onto membranes. LRRK2 signaling is counteracted by the phosphoprotein phosphatase PPM1H, which selectively dephosphorylates phospho-Rab proteins. We present here our current understanding of the structure, biochemical properties, and cell biology of LRRK2 and its related paralog LRRK1 and discuss how this information guides the generation of LRRK2 inhibitors for the potential benefit of patients.
Assuntos
Serina-Treonina Proteína Quinase-2 com Repetições Ricas em Leucina , Doença de Parkinson , Proteínas rab de Ligação ao GTP , Humanos , Serina-Treonina Proteína Quinase-2 com Repetições Ricas em Leucina/metabolismo , Serina-Treonina Proteína Quinase-2 com Repetições Ricas em Leucina/genética , Serina-Treonina Proteína Quinase-2 com Repetições Ricas em Leucina/química , Fosforilação , Doença de Parkinson/metabolismo , Doença de Parkinson/genética , Doença de Parkinson/patologia , Proteínas rab de Ligação ao GTP/metabolismo , Proteínas rab de Ligação ao GTP/genética , Proteínas rab de Ligação ao GTP/química , Animais , Transdução de Sinais , Mutação , Proteínas Serina-Treonina Quinases/metabolismo , Proteínas Serina-Treonina Quinases/genética , Proteínas Serina-Treonina Quinases/química , Ligação Proteica , Fosfoproteínas Fosfatases/metabolismo , Fosfoproteínas Fosfatases/genética , Fosfoproteínas Fosfatases/químicaRESUMO
Ongoing, early-stage clinical trials illustrate the translational potential of human pluripotent stem cell (hPSC)-based cell therapies in Parkinson's disease (PD). However, an unresolved challenge is the extensive cell death following transplantation. Here, we performed a pooled CRISPR-Cas9 screen to enhance postmitotic dopamine neuron survival in vivo. We identified p53-mediated apoptotic cell death as a major contributor to dopamine neuron loss and uncovered a causal link of tumor necrosis factor alpha (TNF-α)-nuclear factor κB (NF-κB) signaling in limiting cell survival. As a translationally relevant strategy to purify postmitotic dopamine neurons, we identified cell surface markers that enable purification without the need for genetic reporters. Combining cell sorting and treatment with adalimumab, a clinically approved TNF-α inhibitor, enabled efficient engraftment of postmitotic dopamine neurons with extensive reinnervation and functional recovery in a preclinical PD mouse model. Thus, transient TNF-α inhibition presents a clinically relevant strategy to enhance survival and enable engraftment of postmitotic hPSC-derived dopamine neurons in PD.
Assuntos
Sobrevivência Celular , Neurônios Dopaminérgicos , NF-kappa B , Fator de Necrose Tumoral alfa , Proteína Supressora de Tumor p53 , Neurônios Dopaminérgicos/metabolismo , Animais , Humanos , NF-kappa B/metabolismo , Proteína Supressora de Tumor p53/metabolismo , Fator de Necrose Tumoral alfa/metabolismo , Camundongos , Sobrevivência Celular/efeitos dos fármacos , Transdução de Sinais , Doença de Parkinson/metabolismo , Células-Tronco Pluripotentes/metabolismo , Apoptose , Modelos Animais de Doenças , Sistemas CRISPR-CasRESUMO
The polyamines putrescine, spermidine, and spermine are abundant polycations of vital importance in mammalian cells. Their cellular levels are tightly regulated by degradation and synthesis, as well as by uptake and export. Here, we discuss the delicate balance between the neuroprotective and neurotoxic effects of polyamines in the context of Parkinson's disease (PD). Polyamine levels decline with aging and are altered in patients with PD, whereas recent mechanistic studies on ATP13A2 (PARK9) demonstrated a driving role of a disturbed polyamine homeostasis in PD. Polyamines affect pathways in PD pathogenesis, such as α-synuclein aggregation, and influence PD-related processes like autophagy, heavy metal toxicity, oxidative stress, neuroinflammation, and lysosomal/mitochondrial dysfunction. We formulate outstanding research questions regarding the role of polyamines in PD, their potential as PD biomarkers, and possible therapeutic strategies for PD targeting polyamine homeostasis.
Assuntos
Doença de Parkinson , Transtornos Parkinsonianos , Animais , Humanos , Doença de Parkinson/genética , Doença de Parkinson/metabolismo , Doença de Parkinson/patologia , Poliaminas/metabolismo , Neuroproteção , Espermidina/metabolismo , Mamíferos/metabolismoRESUMO
Alpha-synuclein (αS) is a conformationally plastic protein that reversibly binds to cellular membranes. It aggregates and is genetically linked to Parkinson's disease (PD). Here, we show that αS directly modulates processing bodies (P-bodies), membraneless organelles that function in mRNA turnover and storage. The N terminus of αS, but not other synucleins, dictates mutually exclusive binding either to cellular membranes or to P-bodies in the cytosol. αS associates with multiple decapping proteins in close proximity on the Edc4 scaffold. As αS pathologically accumulates, aberrant interaction with Edc4 occurs at the expense of physiologic decapping-module interactions. mRNA decay kinetics within PD-relevant pathways are correspondingly disrupted in PD patient neurons and brain. Genetic modulation of P-body components alters αS toxicity, and human genetic analysis lends support to the disease-relevance of these interactions. Beyond revealing an unexpected aspect of αS function and pathology, our data highlight the versatility of conformationally plastic proteins with high intrinsic disorder.
Assuntos
Doença de Parkinson , alfa-Sinucleína , Humanos , Doença de Parkinson/metabolismo , Corpos de Processamento , Estabilidade de RNA , alfa-Sinucleína/genética , alfa-Sinucleína/metabolismoRESUMO
Lysosomes require an acidic lumen between pH 4.5 and 5.0 for effective digestion of macromolecules. This pH optimum is maintained by proton influx produced by the V-ATPase and efflux through an unidentified "H+ leak" pathway. Here we show that TMEM175, a genetic risk factor for Parkinson's disease (PD), mediates the lysosomal H+ leak by acting as a proton-activated, proton-selective channel on the lysosomal membrane (LyPAP). Acidification beyond the normal range potently activated LyPAP to terminate further acidification of lysosomes. An endogenous polyunsaturated fatty acid and synthetic agonists also activated TMEM175 to trigger lysosomal proton release. TMEM175 deficiency caused lysosomal over-acidification, impaired proteolytic activity, and facilitated α-synuclein aggregation in vivo. Mutational and pH normalization analyses indicated that the channel's H+ conductance is essential for normal lysosome function. Thus, modulation of LyPAP by cellular cues may dynamically tune the pH optima of endosomes and lysosomes to regulate lysosomal degradation and PD pathology.
Assuntos
Doença de Parkinson , Endossomos/metabolismo , Humanos , Concentração de Íons de Hidrogênio , Membranas Intracelulares/metabolismo , Lisossomos/metabolismo , Doença de Parkinson/metabolismo , Canais de Potássio/metabolismo , PrótonsRESUMO
Parthanatos-associated apoptosis-inducing factor (AIF) nuclease (PAAN), also known as macrophage migration inhibitor factor (MIF), is a member of the PD-D/E(X)K nucleases that acts as a final executioner in parthanatos. PAAN's role in Parkinson's disease (PD) and whether it is amenable to chemical inhibition is not known. Here, we show that neurodegeneration induced by pathologic α-synuclein (α-syn) occurs via PAAN/MIF nuclease activity. Genetic depletion of PAAN/MIF and a mutant lacking nuclease activity prevent the loss of dopaminergic neurons and behavioral deficits in the α-syn preformed fibril (PFF) mouse model of sporadic PD. Compound screening led to the identification of PAANIB-1, a brain-penetrant PAAN/MIF nuclease inhibitor that prevents neurodegeneration induced by α-syn PFF, AAV-α-syn overexpression, or MPTP intoxication in vivo. Our findings could have broad relevance in human pathologies where parthanatos plays a role in the development of cell death inhibitors targeting the druggable PAAN/MIF nuclease.
Assuntos
Oxirredutases Intramoleculares/metabolismo , Fatores Inibidores da Migração de Macrófagos/metabolismo , Doença de Parkinson , Animais , Encéfalo/metabolismo , Modelos Animais de Doenças , Neurônios Dopaminérgicos/metabolismo , Endonucleases/metabolismo , Camundongos , Doença de Parkinson/tratamento farmacológico , Doença de Parkinson/genética , Doença de Parkinson/metabolismoRESUMO
Mutations in leucine-rich repeat kinase 2 (LRRK2) are the most frequent cause of familial Parkinson's disease. LRRK2 is a multi-domain protein containing a kinase and GTPase. Using correlative light and electron microscopy, in situ cryo-electron tomography, and subtomogram analysis, we reveal a 14-Å structure of LRRK2 bearing a pathogenic mutation that oligomerizes as a right-handed double helix around microtubules, which are left-handed. Using integrative modeling, we determine the architecture of LRRK2, showing that the GTPase and kinase are in close proximity, with the GTPase closer to the microtubule surface, whereas the kinase is exposed to the cytoplasm. We identify two oligomerization interfaces mediated by non-catalytic domains. Mutation of one of these abolishes LRRK2 microtubule-association. Our work demonstrates the power of cryo-electron tomography to generate models of previously unsolved structures in their cellular environment.
Assuntos
Microscopia Crioeletrônica/métodos , Tomografia com Microscopia Eletrônica/métodos , Serina-Treonina Proteína Quinase-2 com Repetições Ricas em Leucina/química , Microtúbulos/metabolismo , Doença de Parkinson/metabolismo , Citoplasma/metabolismo , GTP Fosfo-Hidrolases/química , GTP Fosfo-Hidrolases/metabolismo , Células HEK293 , Humanos , Microscopia Eletrônica de Transmissão , Microtúbulos/química , Modelos Químicos , Mutação , Doença de Parkinson/genética , Doença de Parkinson/patologia , Fosfotransferases/química , Fosfotransferases/metabolismo , Domínios Proteicos , Repetições WD40RESUMO
Conversion of glial cells into functional neurons represents a potential therapeutic approach for replenishing neuronal loss associated with neurodegenerative diseases and brain injury. Previous attempts in this area using expression of transcription factors were hindered by the low conversion efficiency and failure of generating desired neuronal types in vivo. Here, we report that downregulation of a single RNA-binding protein, polypyrimidine tract-binding protein 1 (Ptbp1), using in vivo viral delivery of a recently developed RNA-targeting CRISPR system CasRx, resulted in the conversion of Müller glia into retinal ganglion cells (RGCs) with a high efficiency, leading to the alleviation of disease symptoms associated with RGC loss. Furthermore, this approach also induced neurons with dopaminergic features in the striatum and alleviated motor defects in a Parkinson's disease mouse model. Thus, glia-to-neuron conversion by CasRx-mediated Ptbp1 knockdown represents a promising in vivo genetic approach for treating a variety of disorders due to neuronal loss.
Assuntos
Neurogênese/fisiologia , Neuroglia/metabolismo , Células Ganglionares da Retina/metabolismo , Animais , Sistemas CRISPR-Cas/fisiologia , Diferenciação Celular/fisiologia , Células Cultivadas , Repetições Palindrômicas Curtas Agrupadas e Regularmente Espaçadas/genética , Modelos Animais de Doenças , Dopamina/metabolismo , Regulação da Expressão Gênica/genética , Ribonucleoproteínas Nucleares Heterogêneas/genética , Ribonucleoproteínas Nucleares Heterogêneas/metabolismo , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Doenças do Sistema Nervoso/metabolismo , Neurônios/metabolismo , Doença de Parkinson/metabolismo , Proteína de Ligação a Regiões Ricas em Polipirimidinas/genética , Proteína de Ligação a Regiões Ricas em Polipirimidinas/metabolismo , Células Ganglionares da Retina/fisiologiaRESUMO
Parkinson's disease (PD) is a leading cause of neurodegeneration that is defined by the selective loss of dopaminergic neurons and the accumulation of protein aggregates called Lewy bodies (LBs). The unequivocal identification of Mendelian inherited mutations in 13 genes in PD has provided transforming insights into the pathogenesis of this disease. The mechanistic analysis of several PD genes, including α-synuclein (α-syn), leucine-rich repeat kinase 2 (LRRK2), PTEN-induced kinase 1 (PINK1), and Parkin, has revealed central roles for protein aggregation, mitochondrial damage, and defects in endolysosomal trafficking in PD neurodegeneration. In this review, we outline recent advances in our understanding of these gene pathways with a focus on the emergent role of Rab (Ras analog in brain) GTPases and vesicular trafficking as a common mechanism that underpins how mutations in PD genes lead to neuronal loss. These advances have led to previously distinct genes such as vacuolar protein-sorting-associated protein 35 (VPS35) and LRRK2 being implicated in a common signaling pathway. A greater understanding of these common nodes of vesicular trafficking will be crucial for linking other PD genes and improving patient stratification in clinical trials underway against α-syn and LRRK2 targets.
Assuntos
Doença de Parkinson/metabolismo , Animais , Autofagia , Vesículas Citoplasmáticas/metabolismo , Humanos , Mitocôndrias/metabolismo , Doença de Parkinson/genética , Agregados Proteicos , Transporte ProteicoRESUMO
The majority of protein molecules must fold into defined three-dimensional structures to acquire functional activity. However, protein chains can adopt a multitude of conformational states, and their biologically active conformation is often only marginally stable. Metastable proteins tend to populate misfolded species that are prone to forming toxic aggregates, including soluble oligomers and fibrillar amyloid deposits, which are linked with neurodegeneration in Alzheimer and Parkinson disease, and many other pathologies. To prevent or regulate protein aggregation, all cells contain an extensive protein homeostasis (or proteostasis) network comprising molecular chaperones and other factors. These defense systems tend to decline during aging, facilitating the manifestation of aggregate deposition diseases. This volume of the Annual Review of Biochemistry contains a set of three articles addressing our current understanding of the structures of pathological protein aggregates and their associated disease mechanisms. These articles also discuss recent insights into the strategies cells have evolved to neutralize toxic aggregates by sequestering them in specific cellular locations.
Assuntos
Envelhecimento/metabolismo , Doença de Alzheimer/metabolismo , Doença de Parkinson/metabolismo , Agregação Patológica de Proteínas/metabolismo , Deficiências na Proteostase/metabolismo , Envelhecimento/genética , Envelhecimento/patologia , Doença de Alzheimer/genética , Doença de Alzheimer/patologia , Amiloide/química , Amiloide/genética , Amiloide/metabolismo , Regulação da Expressão Gênica , Humanos , Chaperonas Moleculares/genética , Chaperonas Moleculares/metabolismo , Doença de Parkinson/genética , Doença de Parkinson/patologia , Agregação Patológica de Proteínas/genética , Agregação Patológica de Proteínas/patologia , Conformação Proteica , Dobramento de Proteína , Deficiências na Proteostase/genética , Deficiências na Proteostase/patologiaRESUMO
Peptides and proteins have been found to possess an inherent tendency to convert from their native functional states into intractable amyloid aggregates. This phenomenon is associated with a range of increasingly common human disorders, including Alzheimer and Parkinson diseases, type II diabetes, and a number of systemic amyloidoses. In this review, we describe this field of science with particular reference to the advances that have been made over the last decade in our understanding of its fundamental nature and consequences. We list the proteins that are known to be deposited as amyloid or other types of aggregates in human tissues and the disorders with which they are associated, as well as the proteins that exploit the amyloid motif to play specific functional roles in humans. In addition, we summarize the genetic factors that have provided insight into the mechanisms of disease onset. We describe recent advances in our knowledge of the structures of amyloid fibrils and their oligomeric precursors and of the mechanisms by which they are formed and proliferate to generate cellular dysfunction. We show evidence that a complex proteostasis network actively combats protein aggregation and that such an efficient system can fail in some circumstances and give rise to disease. Finally, we anticipate the development of novel therapeutic strategies with which to prevent or treat these highly debilitating and currently incurable conditions.
Assuntos
Doença de Alzheimer/história , Amiloide/química , Amiloidose/história , Diabetes Mellitus Tipo 2/história , Doença de Parkinson/história , Deficiências na Proteostase/história , Doença de Alzheimer/tratamento farmacológico , Doença de Alzheimer/metabolismo , Doença de Alzheimer/patologia , Amiloide/genética , Amiloide/metabolismo , Amiloidose/tratamento farmacológico , Amiloidose/metabolismo , Amiloidose/patologia , Diabetes Mellitus Tipo 2/tratamento farmacológico , Diabetes Mellitus Tipo 2/metabolismo , Diabetes Mellitus Tipo 2/patologia , Drogas em Investigação , Regulação da Expressão Gênica , História do Século XXI , Humanos , Amiloidose de Cadeia Leve de Imunoglobulina , Chaperonas Moleculares/genética , Chaperonas Moleculares/metabolismo , Terapia de Alvo Molecular , Doença de Parkinson/tratamento farmacológico , Doença de Parkinson/metabolismo , Doença de Parkinson/patologia , Agregação Patológica de Proteínas/história , Agregação Patológica de Proteínas/metabolismo , Agregação Patológica de Proteínas/patologia , Agregação Patológica de Proteínas/prevenção & controle , Conformação Proteica , Dobramento de Proteína , Deficiências na Proteostase/tratamento farmacológico , Deficiências na Proteostase/metabolismo , Deficiências na Proteostase/patologia , Deficiências na Proteostase/prevenção & controleRESUMO
Ageing is a major risk factor for the development of many diseases, prominently including neurodegenerative disorders such as Alzheimer disease and Parkinson disease. A hallmark of many age-related diseases is the dysfunction in protein homeostasis (proteostasis), leading to the accumulation of protein aggregates. In healthy cells, a complex proteostasis network, comprising molecular chaperones and proteolytic machineries and their regulators, operates to ensure the maintenance of proteostasis. These factors coordinate protein synthesis with polypeptide folding, the conservation of protein conformation and protein degradation. However, sustaining proteome balance is a challenging task in the face of various external and endogenous stresses that accumulate during ageing. These stresses lead to the decline of proteostasis network capacity and proteome integrity. The resulting accumulation of misfolded and aggregated proteins affects, in particular, postmitotic cell types such as neurons, manifesting in disease. Recent analyses of proteome-wide changes that occur during ageing inform strategies to improve proteostasis. The possibilities of pharmacological augmentation of the capacity of proteostasis networks hold great promise for delaying the onset of age-related pathologies associated with proteome deterioration and for extending healthspan.
Assuntos
Doença de Alzheimer/metabolismo , Chaperonas Moleculares/metabolismo , Doença de Parkinson/metabolismo , Dobramento de Proteína , Proteólise , Proteostase , Doença de Alzheimer/genética , Doença de Alzheimer/patologia , Animais , Humanos , Chaperonas Moleculares/genética , Doença de Parkinson/genética , Doença de Parkinson/patologiaRESUMO
The intestinal microbiota influence neurodevelopment, modulate behavior, and contribute to neurological disorders. However, a functional link between gut bacteria and neurodegenerative diseases remains unexplored. Synucleinopathies are characterized by aggregation of the protein α-synuclein (αSyn), often resulting in motor dysfunction as exemplified by Parkinson's disease (PD). Using mice that overexpress αSyn, we report herein that gut microbiota are required for motor deficits, microglia activation, and αSyn pathology. Antibiotic treatment ameliorates, while microbial re-colonization promotes, pathophysiology in adult animals, suggesting that postnatal signaling between the gut and the brain modulates disease. Indeed, oral administration of specific microbial metabolites to germ-free mice promotes neuroinflammation and motor symptoms. Remarkably, colonization of αSyn-overexpressing mice with microbiota from PD-affected patients enhances physical impairments compared to microbiota transplants from healthy human donors. These findings reveal that gut bacteria regulate movement disorders in mice and suggest that alterations in the human microbiome represent a risk factor for PD.
Assuntos
Doença de Parkinson/microbiologia , Doença de Parkinson/patologia , Animais , Encéfalo/patologia , Disbiose/patologia , Ácidos Graxos/metabolismo , Microbioma Gastrointestinal , Trato Gastrointestinal/microbiologia , Trato Gastrointestinal/fisiopatologia , Humanos , Inflamação/metabolismo , Inflamação/microbiologia , Inflamação/patologia , Camundongos , Microglia/patologia , Doença de Parkinson/metabolismo , Doença de Parkinson/fisiopatologia , alfa-Sinucleína/metabolismoRESUMO
Maintaining a highly acidic lysosomal pH is central to cellular physiology. Here, we use functional proteomics, single-particle cryo-EM, electrophysiology, and in vivo imaging to unravel a key biological function of human lysosome-associated membrane proteins (LAMP-1 and LAMP-2) in regulating lysosomal pH homeostasis. Despite being widely used as a lysosomal marker, the physiological functions of the LAMP proteins have long been overlooked. We show that LAMP-1 and LAMP-2 directly interact with and inhibit the activity of the lysosomal cation channel TMEM175, a key player in lysosomal pH homeostasis implicated in Parkinson's disease. This LAMP inhibition mitigates the proton conduction of TMEM175 and facilitates lysosomal acidification to a lower pH environment crucial for optimal hydrolase activity. Disrupting the LAMP-TMEM175 interaction alkalinizes the lysosomal pH and compromises the lysosomal hydrolytic function. In light of the ever-increasing importance of lysosomes to cellular physiology and diseases, our data have widespread implications for lysosomal biology.
Assuntos
Doença de Parkinson , Humanos , Concentração de Íons de Hidrogênio , Proteínas de Membrana Lisossomal/genética , Proteínas de Membrana Lisossomal/metabolismo , Lisossomos/metabolismo , Doença de Parkinson/metabolismo , Canais de Potássio/metabolismoRESUMO
Progressive depletion of midbrain dopamine neurons (PDD) is associated with deficits in the initiation, speed, and fluidity of voluntary movement. Models of basal ganglia function focus on initiation deficits; however, it is unclear how they account for deficits in the speed or amplitude of movement (vigor). Using an effort-based operant conditioning task for head-fixed mice, we discovered distinct functional classes of neurons in the dorsal striatum that represent movement vigor. Mice with PDD exhibited a progressive reduction in vigor, along with a selective impairment of its neural representation in striatum. Restoration of dopaminergic tone with a synthetic precursor ameliorated deficits in movement vigor and its neural representation, while suppression of striatal activity during movement was sufficient to reduce vigor. Thus, dopaminergic input to the dorsal striatum is indispensable for the emergence of striatal activity that mediates adaptive changes in movement vigor. These results suggest refined intervention strategies for Parkinson's disease.
Assuntos
Dopamina/metabolismo , Mesencéfalo/metabolismo , Doença de Parkinson/metabolismo , Doença de Parkinson/fisiopatologia , Animais , Gânglios da Base/metabolismo , Modelos Animais de Doenças , Hipocinesia/metabolismo , Hipocinesia/fisiopatologia , Camundongos , Músculo Esquelético/fisiologiaRESUMO
Neurodegenerative diseases have been linked to inflammation, but whether altered immunomodulation plays a causative role in neurodegeneration is not clear. We show that lack of cytokine interferon-ß (IFN-ß) signaling causes spontaneous neurodegeneration in the absence of neurodegenerative disease-causing mutant proteins. Mice lacking Ifnb function exhibited motor and cognitive learning impairments with accompanying α-synuclein-containing Lewy bodies in the brain, as well as a reduction in dopaminergic neurons and defective dopamine signaling in the nigrostriatal region. Lack of IFN-ß signaling caused defects in neuronal autophagy prior to α-synucleinopathy, which was associated with accumulation of senescent mitochondria. Recombinant IFN-ß promoted neurite growth and branching, autophagy flux, and α-synuclein degradation in neurons. In addition, lentiviral IFN-ß overexpression prevented dopaminergic neuron loss in a familial Parkinson's disease model. These results indicate a protective role for IFN-ß in neuronal homeostasis and validate Ifnb mutant mice as a model for sporadic Lewy body and Parkinson's disease dementia.
Assuntos
Interferon beta/metabolismo , Neurônios/metabolismo , Receptor de Interferon alfa e beta/metabolismo , Animais , Autofagia , Modelos Animais de Doenças , Terapia Genética , Interferon beta/genética , Interferon beta/uso terapêutico , Doença por Corpos de Lewy/metabolismo , Doença por Corpos de Lewy/patologia , Camundongos , Camundongos Endogâmicos C57BL , Doença de Parkinson/genética , Doença de Parkinson/metabolismo , Doença de Parkinson/patologia , Doença de Parkinson/terapia , Receptor de Interferon alfa e beta/genética , Transdução de Sinais , Transcriptoma , alfa-Sinucleína/metabolismoRESUMO
As a central hub for cellular metabolism and intracellular signaling, the mitochondrion is a pivotal organelle, dysfunction of which has been linked to several human diseases including neurodegenerative disorders and in particular Parkinson's disease. An inherent challenge that mitochondria face is the continuous exposure to diverse stresses that increase their likelihood of dysregulation. In response, eukaryotic cells have evolved sophisticated quality control mechanisms to monitor, identify, repair, and/or eliminate abnormal or misfolded proteins within the mitochondrion and/or the dysfunctional mitochondrion itself. Chaperones identify unstable or otherwise abnormal conformations in mitochondrial proteins and can promote their refolding to recover their correct conformation and stability. However, if repair is not possible, the abnormal protein is selectively degraded to prevent potentially damaging interactions with other proteins or its oligomerization into toxic multimeric complexes. The autophagic-lysosomal system and the ubiquitin-proteasome system mediate the selective and targeted degradation of such abnormal or misfolded protein species. Mitophagy (a specific kind of autophagy) mediates the selective elimination of dysfunctional mitochondria, to prevent the deleterious effects of the dysfunctional organelles within the cell. Despite our increasing understanding of the molecular responses toward dysfunctional mitochondria, many key aspects remain relatively poorly understood. Here, we review the emerging mechanisms of mitochondrial quality control including quality control strategies coupled to mitochondrial import mechanisms. In addition, we review the molecular mechanisms regulating mitophagy, with an emphasis on the regulation of PINK1/Parkin-mediated mitophagy in cellular physiology and in the context of Parkinson's disease cell biology.
Assuntos
Doença de Parkinson , Autofagia , Humanos , Mitocôndrias/metabolismo , Mitofagia/fisiologia , Doença de Parkinson/metabolismo , Proteínas Quinases/metabolismo , Proteínas Quinases/farmacologiaRESUMO
Parkinson disease (PD) is a neurodegenerative disorder marked by the preferential dysfunction and death of dopaminergic neurons in the substantia nigra. The onset and progression of PD is influenced by a diversity of genetic variants, many of which lack functional characterization. To identify the most high-yield targets for therapeutic intervention, it is important to consider the core cellular compartments and functional pathways upon which the varied forms of pathogenic dysfunction may converge. Here, we review several key PD-linked proteins and pathways, focusing on the mechanisms of their potential convergence in disease pathogenesis. These dysfunctions primarily localize to a subset of subcellular compartments, including mitochondria, lysosomes and synapses. We discuss how these pathogenic mechanisms that originate in different cellular compartments may coordinately lead to cellular dysfunction and neurodegeneration in PD.
Assuntos
Doença de Parkinson , Doença de Parkinson/genética , Doença de Parkinson/patologia , Doença de Parkinson/metabolismo , Humanos , Animais , Mitocôndrias/genética , Mitocôndrias/metabolismo , Neurônios Dopaminérgicos/patologia , Neurônios Dopaminérgicos/metabolismo , Lisossomos/metabolismo , Lisossomos/genética , Sinapses/patologia , Sinapses/genética , Sinapses/metabolismoRESUMO
Parkinson Disease (PD) is a progressive neurodegenerative disorder with limited therapeutic options. In this issue of Cell, Martin et al. link PD protein leucine-rich repeat kinase 2 (LRRK2) to abnormalities of translational control, a pathogenic mechanism implicated in an increasing number of CNS neurodegenerative diseases, as well as in normal aging.
Assuntos
Neurônios/metabolismo , Doença de Parkinson/metabolismo , Proteínas Serina-Treonina Quinases/metabolismo , Proteínas Ribossômicas/metabolismo , Animais , Humanos , Serina-Treonina Proteína Quinase-2 com Repetições Ricas em LeucinaRESUMO
Mutations in leucine-rich repeat kinase 2 (LRRK2) are a common cause of familial and sporadic Parkinson's disease (PD). Elevated LRRK2 kinase activity and neurodegeneration are linked, but the phosphosubstrate that connects LRRK2 kinase activity to neurodegeneration is not known. Here, we show that ribosomal protein s15 is a key pathogenic LRRK2 substrate in Drosophila and human neuron PD models. Phosphodeficient s15 carrying a threonine 136 to alanine substitution rescues dopamine neuron degeneration and age-related locomotor deficits in G2019S LRRK2 transgenic Drosophila and substantially reduces G2019S LRRK2-mediated neurite loss and cell death in human dopamine and cortical neurons. Remarkably, pathogenic LRRK2 stimulates both cap-dependent and cap-independent mRNA translation and induces a bulk increase in protein synthesis in Drosophila, which can be prevented by phosphodeficient T136A s15. These results reveal a novel mechanism of PD pathogenesis linked to elevated LRRK2 kinase activity and aberrant protein synthesis in vivo.