RESUMEN
α-Synuclein (αSyn) is central to the neuropathology of Parkinson's disease (PD) due to its propensity for misfolding and aggregation into neurotoxic oligomers. Nitration/oxidation of αSyn leads to dityrosine crosslinking and aggregation. Myeloperoxidase (MPO) is an oxidant-generating enzyme implicated in neurodegenerative diseases. In the present work we have examined the impact of MPO in PD through analysis of postmortem PD brain and in a novel animal model in which we crossed a transgenic mouse expressing the human MPO (hMPO) gene to a mouse expressing human αSyn-A53T mutant (A53T) (hMPO-A53T). Surprisingly, our results show that in PD substantia nigra, the hMPO gene is expressed in neurons containing aggregates of nitrated αSyn as well as MPO-generated HOCl-modified epitopes. In our hMPO-A53T mouse model, we also saw hMPO expression in neurons but not mouse MPO. In the mouse model, hMPO was expressed in neurons colocalizing with nitrated αSyn, carbamylated lysine, nitrotyrosine, as well as HOCl-modified epitopes/proteins. RNAscope in situ hybridization confirmed hMPO mRNA expression in neurons. Interestingly, the hMPO protein expressed in hMPO-A53T brain is primarily the precursor proMPO, which enters the secretory pathway potentially resulting in interneuronal transmission of MPO and oxidative species. Importantly, the hMPO-A53T mouse model, when compared to the A53T model, exhibited significant exacerbation of motor impairment on rotating rods, balance beams, and wire hang tests. Further, hMPO expression in the A53T model resulted in earlier onset of end stage paralysis. Interestingly, there was a high concentration of αSyn aggregates in the stratum lacunosum moleculare of hippocampal CA2 region, which has been associated in humans with accumulation of αSyn pathology and neural atrophy in dementia with Lewy bodies. This accumulation of αSyn aggregates in CA2 was associated with markers of endoplasmic reticulum (ER) stress and the unfolded protein response with expression of activating transcription factor 4 (ATF4), C/EBP homologous protein (CHOP), MPO, and cleaved caspase-3. Together these findings suggest that MPO plays an important role in nitrative and oxidative damage that contributes to αSyn pathology in synucleinopathies.
Asunto(s)
Modelos Animales de Enfermedad , Trastornos Motores/enzimología , Neuronas/enzimología , Enfermedad de Parkinson/enzimología , Peroxidasa/metabolismo , Sustancia Negra/enzimología , Animales , Carbono/química , Epítopos/química , Femenino , Humanos , Masculino , Aprendizaje por Laberinto , Ratones , Ratones Transgénicos , Trastornos Motores/fisiopatología , Destreza Motora , Nitrógeno/química , Estrés Oxidativo , Enfermedad de Parkinson/fisiopatología , Peroxidasa/genética , Sustancia Negra/citologíaRESUMEN
Glycine encephalopathy (GE), or nonketotic hyperglycinemia (NKH), is a rare recessive genetic disease caused by defective glycine cleavage and characterized by increased accumulation of glycine in all tissues. Here, based on new case reports of GLDC loss-of-function mutations in GE patients, we aimed to generate a zebrafish model of severe GE in order to unravel the molecular mechanism of the disease. Using CRISPR/Cas9, we knocked out the gldc gene and showed that gldc-/- fish recapitulate GE on a molecular level and present a motor phenotype reminiscent of severe GE symptoms. The molecular characterization of gldc-/- mutants showed a broad metabolic disturbance affecting amino acids and neurotransmitters other than glycine, with lactic acidosis at stages preceding death. Although a transient imbalance was found in cell proliferation in the brain of gldc-/- zebrafish, the main brain networks were not affected, thus suggesting that GE pathogenicity is mainly due to metabolic defects. We confirmed that the gldc-/- hypotonic phenotype is due to NMDA and glycine receptor overactivation, and demonstrated that gldc-/- larvae depict exacerbated hyperglycinemia at these synapses. Remarkably, we were able to rescue the motor dysfunction of gldc-/- larvae by counterbalancing pharmacologically or genetically the level of glycine at the synapse.
Asunto(s)
Glicina-Deshidrogenasa (Descarboxilante)/deficiencia , Glicina/sangre , Hiperglicinemia no Cetósica/genética , Trastornos Motores/enzimología , Transmisión Sináptica/efectos de los fármacos , Animales , Encéfalo/diagnóstico por imagen , Encéfalo/metabolismo , Encéfalo/fisiopatología , Proteína 9 Asociada a CRISPR/metabolismo , Dextrometorfano/administración & dosificación , Dextrometorfano/uso terapéutico , Antagonistas de Aminoácidos Excitadores/uso terapéutico , Resultado Fatal , Femenino , Conservantes de Alimentos/uso terapéutico , Glicina/líquido cefalorraquídeo , Glicina-Deshidrogenasa (Descarboxilante)/metabolismo , Humanos , Hiperglicinemia no Cetósica/diagnóstico , Hiperglicinemia no Cetósica/enzimología , Recién Nacido , Masculino , Persona de Mediana Edad , Trastornos Motores/fisiopatología , Mutación , Fenotipo , Benzoato de Sodio/administración & dosificación , Benzoato de Sodio/uso terapéutico , Resultado del Tratamiento , Pez CebraAsunto(s)
Errores Innatos del Metabolismo de los Aminoácidos/fisiopatología , Discapacidades del Desarrollo/enzimología , Succionato-Semialdehído Deshidrogenasa/deficiencia , Errores Innatos del Metabolismo de los Aminoácidos/diagnóstico por imagen , Preescolar , Discapacidades del Desarrollo/diagnóstico por imagen , Discapacidades del Desarrollo/fisiopatología , Globo Pálido/diagnóstico por imagen , Humanos , Lamotrigina/uso terapéutico , Imagen por Resonancia Magnética , Masculino , Trastornos Motores/tratamiento farmacológico , Trastornos Motores/enzimología , Trastornos Motores/fisiopatología , Hipotonía Muscular/enzimología , Hipotonía Muscular/fisiopatología , Risperidona/uso terapéuticoRESUMEN
Liver hydrolysate (LH) is used as a pharmaceutical agent in Japan, to enhance liver function. However, the effects of LH on sickness behavior are unknown. This study investigated the effect of LH on sickness behaviors, such as concanavalin A (ConA)-induced reduction of locomotor activity. ConA treatment significantly decreased locomotor activity. The striatal tyrosine hydroxylase (TH) levels were also significantly decreased following ConA treatment. The decreased locomotor activity and TH levels were significantly reversed by LH treatment. LH may prove beneficial for preventing sickness behavior following ConA treatment, at least in part, by activating TH in the striatum.