RESUMEN
BACKGROUND AND PURPOSE: Mutations of the LRRK2 gene are now recognized as major risk factors for Parkinson's disease. The Lrrk2 protein is a member of the ROCO family, which also includes Lrrk1 and Dapk1. Functional genetic variants of the DAPK1 gene (rs4877365 and rs4878104) have been previously associated with Alzheimer's disease. METHODS: Herein, we assessed the role of DAPK1 variants (rs4877365 and rs4878104) in risk of Parkinson's disease with Sequenom iPLEX genotyping, employing one Taiwanese series (391 patients with Parkinson's disease, 344 controls) and five separate Caucasian series' (combined sample size 1962 Parkinson's disease patients, 1900 controls). RESULTS: We observed no evidence of association for rs4877365 and rs4878104 and risk of Parkinson's disease in any of the individual series or in the combined Caucasian series under either an additive or recessive model. CONCLUSION: These specific DAPK1 intronic variants do not increase the risk of Parkinson's disease. However, further functional studies are required to elucidate the potential therapeutic implications with the dimerization of the Dapk1 and Lrrk2 proteins.
Asunto(s)
Proteínas Reguladoras de la Apoptosis/genética , Proteínas Quinasas Dependientes de Calcio-Calmodulina/genética , Predisposición Genética a la Enfermedad/genética , Variación Genética/genética , Enfermedad de Parkinson/genética , Polimorfismo de Nucleótido Simple/genética , Adulto , Anciano , Anciano de 80 o más Años , Estudios de Casos y Controles , Proteínas Quinasas Asociadas a Muerte Celular , Femenino , Predisposición Genética a la Enfermedad/etnología , Humanos , Estudios Longitudinales , Masculino , Persona de Mediana Edad , Enfermedad de Parkinson/etnología , Multimerización de Proteína , Adulto JovenRESUMEN
Mutations in the Leucine Rich Repeat Kinase 2 (LRRK2) gene, first described in 2004 have now emerged as the most important genetic finding in both autosomal dominant and sporadic Parkinson's disease (PD). While a formidable research effort has ensued since the initial gene discovery, little is known of either the normal or the pathological role of LRRK2. We have created lines of mice that express human wild-type (hWT) or G2019S Lrrk2 via bacterial artificial chromosome (BAC) transgenesis. In vivo analysis of the dopaminergic system revealed abnormal dopamine neurotransmission in both hWT and G2019S transgenic mice evidenced by a decrease in extra-cellular dopamine levels, which was detected without pharmacological manipulation. Immunopathological analysis revealed changes in localization and increased phosphorylation of microtubule binding protein tau in G2019S mice. Quantitative biochemical analysis confirmed the presence of differential phospho-tau species in G2019S mice but surprisingly, upon dephosphorylation the tau isoform banding pattern in G2019S mice remained altered. This suggests that other post-translational modifications of tau occur in G2019S mice. We hypothesize that Lrrk2 may impact on tau processing which subsequently leads to increased phosphorylation. Our models will be useful for further understanding of the mechanistic actions of LRRK2 and future therapeutic screening.
Asunto(s)
Encéfalo/metabolismo , Proteínas Serina-Treonina Quinasas/genética , Transmisión Sináptica/fisiología , Proteínas tau/metabolismo , Animales , Autorradiografía , Cromatografía Líquida de Alta Presión , Cromosomas Artificiales Bacterianos , Dopamina/metabolismo , Humanos , Immunoblotting , Hibridación in Situ , Proteína 2 Quinasa Serina-Treonina Rica en Repeticiones de Leucina , Masculino , Ratones , Ratones Transgénicos , Microdiálisis , Fosforilación , Procesamiento Proteico-Postraduccional , Receptores de Dopamina D1/metabolismo , Receptores de Dopamina D2/metabolismo , Reacción en Cadena de la Polimerasa de Transcriptasa InversaRESUMEN
OBJECTIVE: Recently, mutations in DCTN1 were found to cause Perry syndrome, a parkinsonian disorder with TDP-43-positive pathology. Previously, mutations in DCTN1 were identified in a family with lower motor neuron disease, in amyotrophic lateral sclerosis (ALS), and in a family with ALS/frontotemporal dementia (FTD), suggesting a central role for DCTN1 in neurodegeneration. METHODS: In this study we sequenced all DCTN1 exons and exon-intron boundaries in 286 samples diagnosed with Parkinson disease (PD), frontotemporal lobar degeneration (FTLD), or ALS. RESULTS: This analysis revealed 36 novel variants (9 missense, 5 silent, and 22 noncoding). Segregation analysis in families and association studies in PD, FTLD, and ALS case-control series did not identify any variants segregating with disease or associated with increased disease risk. CONCLUSIONS: This study suggests that pathogenic mutations in DCTN1 are rare and do not play a common role in the development of Parkinson disease, frontotemporal lobar degeneration, or amyotrophic lateral sclerosis.
Asunto(s)
Esclerosis Amiotrófica Lateral/genética , Demencia/genética , Predisposición Genética a la Enfermedad/genética , Proteínas Asociadas a Microtúbulos/genética , Enfermedad de Parkinson/genética , Anciano , Anciano de 80 o más Años , Estudios de Casos y Controles , Análisis Mutacional de ADN , Proteínas de Unión al ADN/genética , Complejo Dinactina , Exones/genética , Femenino , Frecuencia de los Genes/genética , Marcadores Genéticos/genética , Pruebas Genéticas , Variación Genética/genética , Genotipo , Humanos , Masculino , Persona de Mediana Edad , Mutación/genéticaRESUMEN
Pathogenic substitutions in leucine-rich repeat kinase 2 (LRRK2, Lrrk2) have been genetically linked to familial, late-onset Parkinsonism. End-stage disease is predominantly associated with nigral neuronal loss and Lewy body pathology, but patients may have gliosis, tau or ubiquitin inclusions (pleomorphic pathology). The anatomical distribution of Lrrk2 protein may provide insight into its function in health and neurodegeneration, thus we performed a comparative study with 'in-house' and commercially available Lrrk2 antibodies using brain tissue from wild type and human Lrrk2 transgenic bacterial artificial chromosome (BAC) mice, and from diffuse Lewy body disease (DLBD) patients. Lrrk2 protein was ubiquitously expressed and relatively abundant in most brain regions, including the substantia nigra, thalamus and striatum. Lrrk2 was not a major component of Lewy body or neuritic pathology associated with Parkinson's disease. However, selective loss of dopaminergic neurons in Lrrk2-associated Parkinsonism argues the protein may have regional-specific interactions. Lrrk2 immunohistochemical staining was present in the subventricular zone, a region containing stem cells that give rise to both neurons and glia. A role for Lrrk2 in neurogenesis might provide further insight into the aberrant role of mutant protein in age-associated neurodegeneration with pleomorphic pathology.
Asunto(s)
Encéfalo/enzimología , Expresión Génica/fisiología , Enfermedad por Cuerpos de Lewy/metabolismo , Proteínas Serina-Treonina Quinasas/metabolismo , Animales , Autorradiografía , Encéfalo/patología , Línea Celular Transformada , Cromosomas Artificiales Bacterianos/fisiología , Expresión Génica/genética , Proteínas Fluorescentes Verdes/metabolismo , Humanos , Proteína 2 Quinasa Serina-Treonina Rica en Repeticiones de Leucina , Enfermedad por Cuerpos de Lewy/patología , Ratones , Ratones Transgénicos , Molécula L1 de Adhesión de Célula Nerviosa/metabolismo , Proteínas Serina-Treonina Quinasas/genética , Ácidos Siálicos/metabolismo , Transfección/métodos , Tirosina 3-Monooxigenasa/metabolismoRESUMEN
Pathogenic Lrrk2 Y1699C substitution observed in a large German-Canadian kindred presents a neurodegenerative disorder that is reminiscent of amyotrophic lateral sclerosis and Parkinsonism-Dementia Complex. We screened 54 patients with ALS for seven known Lrrk2 pathogenic substitutions in the Roc, COR and kinase domains. No mutations were observed suggesting that this locus does not have a major influence on the ALS phenotype. However we can not rule out other genetic variation at the LRRK2 locus may play a role in parkinsonian disorders with amyotrophic lateral sclerosis and may be considered candidates for genetic screening.
Asunto(s)
Esclerosis Amiotrófica Lateral/genética , Esclerosis Amiotrófica Lateral/metabolismo , Sistema Nervioso Central/metabolismo , Predisposición Genética a la Enfermedad/genética , Mutación/genética , Proteínas Serina-Treonina Quinasas/genética , Adolescente , Adulto , Anciano , Sustitución de Aminoácidos/genética , Esclerosis Amiotrófica Lateral/fisiopatología , Secuencia de Bases/genética , Sistema Nervioso Central/fisiopatología , Análisis Mutacional de ADN , Femenino , Pruebas Genéticas , Variación Genética/genética , Genotipo , Humanos , Proteína 2 Quinasa Serina-Treonina Rica en Repeticiones de Leucina , Masculino , Persona de Mediana Edad , Fenotipo , Proteínas Serina-Treonina Quinasas/química , Estructura Terciaria de Proteína/genéticaRESUMEN
Lrrk2 G2019S is predominantly associated with alpha-synuclein-immunopositive Lewy body pathology. We have identified Family SK where Lrrk2 G2019S segregates with slowly progressive parkinsonism and the affected proband has tau-immunopositive neurofibrillary tangle pathology. Thus alpha-synucleinopathy and tauopathy, the predominant pathologies associated with parkinsonism, may be alternate outcomes of the same underlying genetic cause. Intriguingly, we observe no evidence of a direct interaction between either the tau or alpha-synuclein protein with Lrrk2.
Asunto(s)
Mutación , Ovillos Neurofibrilares/metabolismo , Trastornos Parkinsonianos/genética , Trastornos Parkinsonianos/patología , Proteínas Serina-Treonina Quinasas/genética , Proteínas tau/metabolismo , Anciano , Encéfalo/metabolismo , Encéfalo/patología , Línea Celular , Evaluación de la Discapacidad , Progresión de la Enfermedad , Femenino , Glicina , Humanos , Inmunohistoquímica , Proteína 2 Quinasa Serina-Treonina Rica en Repeticiones de Leucina , Masculino , Persona de Mediana Edad , Ovillos Neurofibrilares/patología , Trastornos Parkinsonianos/fisiopatología , Linaje , Serina , alfa-Sinucleína/metabolismoRESUMEN
Mutations in the parkin gene cause autosomal-recessive early-onset parkinsonism as a result of the degeneration of mesencephalic dopaminergic neurons. In cell culture models, parkin expression has been shown to protect against cell death mediated by the sphingolipid ceramide. To determine whether the antiapoptotic effect of parkin involves changes in gene expression, we used Affymetrix oligonucleotide microarrays to analyse gene expression in stably transfected PC12 cells which conditionally overexpress parkin, that were treated or not with C2-ceramide. Overexpression of parkin and ceramide treatment both modulated gene expression. A number of the genes upregulated in the presence of ceramide, and modulated by parkin, were associated with apoptosis or cellular stress reactions. We validated the upregulation of four such genes (CHK, EIF4EBP1, GADD45A and PTPN-5) by real-time PCR after 3, 6, 9 and 12 h of ceramide treatment in cells that overexpressed parkin or not. All were upregulated 2 to 11-fold, 3 and 6 h after application of ceramide. Parkin overexpression reduced the upregulation of EIF4EBP1, GADD45A and PTPN-5, but only at 6 h. These results suggest that, in this assay, the cytoprotective effect of parkin might result not only from its E3-ligase activity, but also from direct or indirect modulation of gene expression in a time-dependent manner.
Asunto(s)
Ceramidas/farmacología , Regulación de la Expresión Génica/efectos de los fármacos , Ubiquitina-Proteína Ligasas/metabolismo , Animales , Humanos , Células PC12 , ARN Mensajero/genética , Ratas , Transcripción Genética/efectos de los fármacos , Transcripción Genética/genética , Ubiquitina-Proteína Ligasas/genéticaRESUMEN
Mutations in the parkin gene encoding an E3 ligase are responsible for autosomal recessive Parkinson's disease. Putative parkin substrates and interacting partners have been identified, but the molecular mechanism underlying parkin-related neurodegeneration is still unclear. We have identified the 20S proteasomal subunit alpha4 (synonyms: PSMA7, XAPC7, subunit alpha type 7) as a new interacting partner of parkin. The C-terminal IBR-RING domain of parkin and the C-terminal part of alpha4 were essential for the interaction. Biochemical studies revealed that alpha4 was not a substrate for parkin-dependent ubiquitylation. Putative functions of the interaction might therefore be substrate presentation to the proteasome or regulation of proteasomal activity. Full-length parkin and parkin lacking the N-terminal ubiquitin-like domain slightly increased the proteasomal activity in HEK 293T cells, in line with the latter hypothesis.