RESUMEN
BACKGROUND: The exact mechanisms underlying neuroinflammation and how they contribute to amyotrophic lateral sclerosis (ALS) pathogenesis remain unclear. One possibility is the secretion of neurotoxic factors, such as lipocalin-2 (LCN2), that lead to neuronal death. METHODS: LCN2 levels were measured in human postmortem tissue using Western blot, quantitative real time polymerase chain reaction, and immunofluorescence, and in plasma by enzyme-linked immunosorbent assay. SH-SY5Y cells were used to test the pro-inflammatory effects of LCN2. RESULTS: LCN2 is increased in ALS postmortem motor cortex, spinal cord, and plasma. Furthermore, we identified several LCN2 variants in ALS patients that may contribute to disease pathogenesis. Lastly, while LCN2 treatment caused cell death and increased pro-inflammatory markers, treatment with an anti-LCN2 antibody prevented these responses in vitro. CONCLUSIONS: LCN2 upregulation in ALS postmortem samples and plasma may be an upstream event for triggering neuroinflammation and neuronal death.
Asunto(s)
Esclerosis Amiotrófica Lateral/genética , Inflamación/metabolismo , Lipocalina 2/genética , Corteza Motora/metabolismo , Médula Espinal/metabolismo , Adulto , Anciano , Anciano de 80 o más Años , Esclerosis Amiotrófica Lateral/metabolismo , Esclerosis Amiotrófica Lateral/fisiopatología , Western Blotting , Estudios de Casos y Controles , Muerte Celular , Línea Celular Tumoral , Citocinas/efectos de los fármacos , Citocinas/metabolismo , Ensayo de Inmunoadsorción Enzimática , Femenino , Técnica del Anticuerpo Fluorescente , Humanos , Técnicas In Vitro , Lipocalina 2/antagonistas & inhibidores , Lipocalina 2/metabolismo , Lipocalina 2/farmacología , Masculino , Persona de Mediana Edad , Polimorfismo de Nucleótido Simple , Reacción en Cadena en Tiempo Real de la PolimerasaRESUMEN
The Hippo signaling pathway is involved in organ size regulation and tumor suppression. Although inhibition of Hippo leads to tumorigenesis, activation of Hippo may play a role in neurodegeneration. Specifically, activation of the upstream regulator, mammalian sterile 20 (STE20)-like kinase 1 (MST1), reduces activity of the transcriptional co-activator Yes-Associated Protein (YAP), thereby mediating oxidative stress-induced neuronal death. Here, we investigated the possible role of this pathway in Huntington's disease (HD) pathogenesis. Our results demonstrate a significant increase in phosphorylated MST1, the active form, in post-mortem HD cortex and in the brains of CAG knock-in HdhQ111/Q111 mice. YAP nuclear localization was also decreased in HD post-mortem cortex and in neuronal stem cells derived from HD patients. Moreover, there was a significant increase in phosphorylated YAP, the inactive form, in HD post-mortem cortex and in HdhQ111/Q111 brain. In addition, YAP was found to interact with huntingtin (Htt) and the chaperone 14-3-3, however this interaction was not altered in the presence of mutant Htt. Lastly, YAP/TEAD interactions and expression of Hippo pathway genes were altered in HD. Together, these results demonstrate that activation of MST1 together with a decrease in nuclear YAP could significantly contribute to transcriptional dysregulation in HD.
Asunto(s)
Encéfalo/patología , Enfermedad de Huntington/metabolismo , Enfermedad de Huntington/patología , Células-Madre Neurales/metabolismo , Proteínas Serina-Treonina Quinasas/metabolismo , Transducción de Señal , Proteínas 14-3-3/metabolismo , Proteínas Adaptadoras Transductoras de Señales/genética , Proteínas Adaptadoras Transductoras de Señales/metabolismo , Animales , Modelos Animales de Enfermedad , Vía de Señalización Hippo , Humanos , Células-Madre Neurales/patología , Fosfoproteínas/genética , Fosfoproteínas/metabolismo , Fosforilación , Unión Proteica , ARN Mensajero/genética , ARN Mensajero/metabolismo , Factores de Transcripción , Transcripción Genética , Proteínas Señalizadoras YAPRESUMEN
Pediatric hepatocellular carcinoma (HCC) is a rare tumor which is associated with an extremely high mortality rate due to lack of effective chemotherapy. Recently, the Hippo pathway and its transcriptional co-activator Yes-associated protein (YAP) have been shown to play a role in hepatocyte proliferation and development of HCC in animal models. Therefore, we sought to examine the activity of YAP and the expression of Hippo pathway components in tumor and non-neoplastic liver tissue from 7 pediatric patients with moderately differentiated HCC. None of the patients had underlying cirrhosis or viral hepatitis, which is commonly seen in adults with HCC. This highlights a major difference in the pathogenesis of HCC between children and adults. We found a statistically significant increase in YAP nuclear localization in 100% of tumors. YAP target gene (CCNE1, CTGF, Cyr61) mRNA expression was also increased in the tumors that had the most significant increase in YAP nuclear localization. Based on Ki67 co-localization studies YAP nuclear localization was not simply a marker of proliferation. Our results demonstrate a clear increase in YAP activity in moderately differentiated pediatric HCC, providing evidence that it may play an important role in tumor survival and propagation.