RESUMO
The molecular mechanisms underlying seizure generation remain elusive, yet they are crucial for developing effective treatments for epilepsy. The current study shows that inhibiting c-Abl tyrosine kinase prevents apoptosis, reduces dendritic spine loss, and maintains N-methyl-d-aspartate (NMDA) receptor subunit 2B (NR2B) phosphorylated in in vitro models of excitotoxicity. Pilocarpine-induced status epilepticus (SE) in mice promotes c-Abl phosphorylation, and disrupting c-Abl activity leads to fewer seizures, increases latency toward SE, and improved animal survival. Currently, clinically used c-Abl inhibitors are non-selective and have poor brain penetration. The allosteric c-Abl inhibitor, neurotinib, used here has favorable potency, selectivity, pharmacokinetics, and vastly improved brain penetration. Neurotinib-administered mice have fewer seizures and improved survival following pilocarpine-SE induction. Our findings reveal c-Abl kinase activation as a key factor in ictogenesis and highlight the impact of its inhibition in preventing the insurgence of epileptic-like seizures in rodents and humans.
Assuntos
Pilocarpina , Proteínas Proto-Oncogênicas c-abl , Convulsões , Animais , Masculino , Camundongos , Apoptose/efeitos dos fármacos , Camundongos Endogâmicos C57BL , Neurônios/efeitos dos fármacos , Neurônios/patologia , Neurônios/metabolismo , Fosforilação/efeitos dos fármacos , Inibidores de Proteínas Quinases/farmacologia , Proteínas Proto-Oncogênicas c-abl/metabolismo , Proteínas Proto-Oncogênicas c-abl/antagonistas & inibidores , Pirimidinas/farmacologia , Pirimidinas/uso terapêutico , Convulsões/induzido quimicamente , Convulsões/tratamento farmacológico , Convulsões/patologia , Estado Epiléptico/induzido quimicamente , Estado Epiléptico/tratamento farmacológico , Estado Epiléptico/patologiaRESUMO
The endoplasmic reticulum is a subcellular organelle key in the control of synthesis, folding, and sorting of proteins. Under endoplasmic reticulum stress, an adaptative unfolded protein response is activated; however, if this activation is prolonged, cells can undergo cell death, in part due to oxidative stress and mitochondrial fragmentation. Here, we report that endoplasmic reticulum stress activates c-Abl tyrosine kinase, inducing its translocation to mitochondria. We found that endoplasmic reticulum stress-activated c-Abl interacts with and phosphorylates the mitochondrial fusion protein MFN2, resulting in mitochondrial fragmentation and apoptosis. Moreover, the pharmacological or genetic inhibition of c-Abl prevents MFN2 phosphorylation, mitochondrial fragmentation, and apoptosis in cells under endoplasmic reticulum stress. Finally, in the amyotrophic lateral sclerosis mouse model, where endoplasmic reticulum and oxidative stress has been linked to neuronal cell death, we demonstrated that the administration of c-Abl inhibitor neurotinib delays the onset of symptoms. Our results uncovered a function of c-Abl in the crosstalk between endoplasmic reticulum stress and mitochondrial dynamics via MFN2 phosphorylation.
RESUMO
Background: Growing evidence suggests that the non-receptor tyrosine kinase, c-Abl, plays a significant role in the pathogenesis of Alzheimer's disease (AD). Here, we analyzed the effect of c-Abl on the cognitive performance decline of APPSwe/PSEN1ΔE9 (APP/PS1) mouse model for AD. Methods: We used the conditional genetic ablation of c-Abl in the brain (c-Abl-KO) and pharmacological treatment with neurotinib, a novel allosteric c-Abl inhibitor with high brain penetrance, imbued in rodent's chow. Results: We found that APP/PS1/c-Abl-KO mice and APP/PS1 neurotinib-fed mice had improved performance in hippocampus-dependent tasks. In the object location and Barnes-maze tests, they recognized the displaced object and learned the location of the escape hole faster than APP/PS1 mice. Also, APP/PS1 neurotinib-fed mice required fewer trials to reach the learning criterion in the memory flexibility test. Accordingly, c-Abl absence and inhibition caused fewer amyloid plaques, reduced astrogliosis, and preserved neurons in the hippocampus. Discussion: Our results further validate c-Abl as a target for AD, and the neurotinib, a novel c-Abl inhibitor, as a suitable preclinical candidate for AD therapies.
RESUMO
Niemann-Pick type A (NPA) disease is a fatal lysosomal neurodegenerative disorder caused by the deficiency in acid sphingomyelinase (ASM) activity. NPA patients present severe and progressive neurodegeneration starting at an early age. Currently, there is no effective treatment for this disease and NPA patients die between 2 and 3 years of age. NPA is characterized by an accumulation of sphingomyelin in lysosomes and dysfunction in the autophagy-lysosomal pathway. Recent studies show that c-Abl tyrosine kinase activity downregulates autophagy and the lysosomal pathway. Interestingly, this kinase is also activated in other lysosomal neurodegenerative disorders. Here, we describe that c-Abl activation contributes to the mechanisms of neuronal damage and death in NPA disease. Our data demonstrate that: 1) c-Abl is activated in-vitro as well as in-vivo NPA models; 2) imatinib, a clinical c-Abl inhibitor, reduces autophagy-lysosomal pathway alterations, restores autophagy flux, and lowers sphingomyelin accumulation in NPA patient fibroblasts and NPA neuronal models and 3) chronic treatment with nilotinib and neurotinib, two c-Abl inhibitors with differences in blood-brain barrier penetrance and target binding mode, show further benefits. While nilotinib treatment reduces neuronal death in the cerebellum and improves locomotor functions, neurotinib decreases glial activation, neuronal disorganization, and loss in hippocampus and cortex, as well as the cognitive decline of NPA mice. Our results support the participation of c-Abl signaling in NPA neurodegeneration and autophagy-lysosomal alterations, supporting the potential use of c-Abl inhibitors for the clinical treatment of NPA patients.
RESUMO
One of the pathological hallmarks of Alzheimer's disease (AD) is the presence of amyloid plaques, which are deposits of misfolded and aggregated amyloid-beta peptide (Aß). The role of the c-Abl tyrosine kinase in Aß-mediated neurodegeneration has been previously reported. Here, we investigated the therapeutic potential of inhibiting c-Abl using imatinib. We developed a novel method, based on a technique used to detect prions (PMCA), to measure minute amounts of misfolded-Aß in the blood of AD transgenic mice. We found that imatinib reduces Aß-oligomers in plasma, which correlates with a reduction of AD brain features such as plaques and oligomers accumulation, neuroinflammation, and cognitive deficits. Cells exposed to imatinib and c-Abl KO mice display decreased levels of ß-CTF fragments, suggesting that an altered processing of the amyloid-beta protein precursor is the most probable mechanism behind imatinib effects. Our findings support the role of c-Abl in Aß accumulation and AD, and propose AD-PMCA as a new tool to evaluate AD progression and screening for drug candidates.
Assuntos
Doença de Alzheimer/sangue , Doença de Alzheimer/enzimologia , Peptídeos beta-Amiloides/sangue , Inibidores de Proteínas Quinases/farmacologia , Proteínas Proto-Oncogênicas c-abl/antagonistas & inibidores , Proteínas Proto-Oncogênicas c-abl/sangue , Doença de Alzheimer/patologia , Animais , Linhagem Celular , Hipocampo/efeitos dos fármacos , Hipocampo/metabolismo , Hipocampo/patologia , Camundongos , Camundongos Knockout , Camundongos TransgênicosRESUMO
BACKGROUND: Niemann-Pick type C (NPC) disease is a fatal neurodegenerative disorder characterized by the accumulation of free cholesterol in lysosomes. There are currently no effective FDA-approved treatments for NPC, although in the last years the inhibition of histone deacetylases (HDACs) has emerged as a potential treatment for this disease. However, the molecular mechanisms that deregulate HDAC activity in NPC disease are unknown. Previously our group had shown that the proapoptotic tyrosine kinase c-Abl signaling is activated in NPC neurons. Here, we demonstrate that c-Abl activity increases HDAC2 levels inducing neuronal gene repression of key synaptic genes in NPC models. RESULTS: Our data show that: i) HDAC2 levels and activity are increased in NPC neuronal models and in Npc1(-/-) mice; ii) inhibition of c-Abl or c-Abl deficiency prevents the increase of HDAC2 protein levels and activity in NPC neuronal models; iii) c-Abl inhibition decreases the levels of HDAC2 tyrosine phosphorylation; iv) treatment with methyl-ß-cyclodextrin and vitamin E decreases the activation of the c-Abl/HDAC2 pathway in NPC neurons; v) in vivo treatment with two c-Abl inhibitors prevents the increase of HDAC2 protein levels in the brain of Npc1(-/-) mice; and vi) c-Abl inhibition prevents HDAC2 recruitment to the promoter of neuronal genes, triggering an increase in their expression. CONCLUSION: Our data show the involvement of the c-Abl/HDAC2 signaling pathway in the regulation of neuronal gene expression in NPC neuronal models. Thus, inhibition of c-Abl could be a pharmacological target for preventing the deleterious effects of increased HDAC2 levels in NPC disease.
Assuntos
Histona Desacetilase 2/genética , Neurônios/metabolismo , Doença de Niemann-Pick Tipo C/genética , Proteínas Proto-Oncogênicas c-abl/genética , Animais , Colesterol/genética , Colesterol/metabolismo , Ciclodextrinas/administração & dosagem , Modelos Animais de Doenças , Regulação da Expressão Gênica/efeitos dos fármacos , Histona Desacetilase 2/biossíntese , Humanos , Lisossomos/metabolismo , Camundongos , Neurônios/patologia , Doença de Niemann-Pick Tipo C/tratamento farmacológico , Doença de Niemann-Pick Tipo C/patologia , Proteínas Proto-Oncogênicas c-abl/biossíntese , Transdução de Sinais/efeitos dos fármacos , Vitamina E/administração & dosagemRESUMO
La enfermedad de Parkinson (EP) es común y se debe a degeneración de las neuronas dopaminérgicas en la sustancia nigra y en otras áreas del cerebro. Varios genes y mutaciones han sido implicados en ella y la mayoría de estas últimas han sido identificadas en el gen PARK2. Reportamos la evaluación de este gen PARK2 y de su región flanqueante en una gran familia de origen caucano, al suroccidente de Colombia. Los padres son primos hermanos y cuatro de sus diez hijos resultaron afectados en edad juvenil. La evaluación molecular incluyó tipificación de microsatélites (STR) y la secuencia directa de los exones del gen. Nuestros hallazgos evidenciaron la presencia en condición homocigota de la mutación c.255delA, en el exón 2 de PARK2. Además, se pudo identificar un haplotipo portado por ambos padres y presente en condición homocigota en los hijos afectados. Del mismo modo se observó una alta tasa de recombinantes en la extensión de la región cromosómica analizada. La mutación c.255delA en PARK2 ya había sido reportada previamente en familias tanto de Francia como de España. Nuestros resultados reconfirman la participación del gen PARK2 en la etiología de la enfermedad de Parkinson, en particular de la forma juvenil. Además, considerando que la mutación identificada en la familia que presentamos ya había sido previamente encontrada en poblaciones europeas, es probable que haya llegado a Colombia desde allí. Alternativamente, esta mutación pudo ocurrir de manera recurrente en un ancestro más cercano de la familia estudiada; para verificar ambas posibilidades sería necesario evaluar marcadores flanqueantes de la mutación, en los cromosomas europeos y colombianos portadores de la mutación. Tales marcadores pueden ser STR (como se reporta en este estudio) o alternativamente, SNP.
Parkinson´s is a common disease (PD) caused by degeneration of dopaminergic neurons in the substantia nigra and other brain areas. Several genes and mutations have been implicated in its pathogenesis, the latter have been identified mainly in the PARK2 gene. We report the evaluation of this gene and of its flanking region in a large family from the southwestern part of Colombia. The parents are first cousins and four out of their ten children were affected at juvenile age. Molecular evaluation included typing of microsatelites (SSTRs) and direct sequencing of the exons of the gene. Our findings showed the presence, in a homozygous manner, of the mutation c.255delA, at exon 2 of PARK2. In addition, it was possible to identify a haplotype carried by both parents, and present in a homozygous manner in the affected children. A high rate of recombinants was observed in the analysed chromosomal region. Mutation c.255delA in PARK2 had been previously reported in families from both France and Spain. Our findings reconfirm the role of the PARK2 gene in the etiology of Parkinson´s disease, in particular of its juvenile form. Furthermore, taking into account that the identified mutation had been previously found in European populations, it is likely that it came into Colombia from that continent. Alternatively, this mutation might have occurred in a recurrent manner in a close ancestor of the studied family. In order to verify both possibilities it would be necessary to test flanking markers of the mutation in both European and Colombian chromosomes carrying it. Such markers could be either STRs, as reported in this study, or SNPs.
Assuntos
Genética Médica , Mutação , Transtornos ParkinsonianosRESUMO
Este artículo presenta un caso de narcolepsia en un paciente de 36 años de edad, celador de profesión; se discuten la etiología, la fisiopatología, el proceso diagnóstico y las implicaciones laborales de los trastornos de sueño...