RESUMO
Alzheimer's disease (AD) is the most prevalent age-associated neurodegenerative disease. A decrease in autophagy during aging contributes to brain disorders by accumulating potentially toxic substrates in neurons. Rubicon is a well-established inhibitor of autophagy in all cells. However, Rubicon participates in different pathways depending on cell type, and little information is currently available on neuronal Rubicon's role in the AD context. Here, we investigated the cell-specific expression of Rubicon in postmortem brain samples from AD patients and 5xFAD mice and its impact on amyloid ß burden in vivo and neuroblastoma cells. Further, we assessed Rubicon levels in human-induced pluripotent stem cells (hiPSCs), derived from early-to-moderate AD and in postmortem samples from severe AD patients. We found increased Rubicon levels in AD-hiPSCs and postmortem samples and a notable Rubicon localization in neurons. In AD transgenic mice lacking Rubicon, we observed intensified amyloid ß burden in the hippocampus and decreased Pacer and p62 levels. In APP-expressing neuroblastoma cells, increased APP/amyloid ß secretion in the medium was found when Rubicon was absent, which was not observed in cells depleted of Atg5, essential for autophagy, or Rab27a, required for exosome secretion. Our results propose an uncharacterized role of Rubicon on APP/amyloid ß homeostasis, in which neuronal Rubicon is a repressor of APP/amyloid ß secretion, defining a new way to target AD and other similar diseases therapeutically.
Assuntos
Doença de Alzheimer , Proteínas Relacionadas à Autofagia , Neuroblastoma , Doenças Neurodegenerativas , Doença de Alzheimer/metabolismo , Peptídeos beta-Amiloides/metabolismo , Precursor de Proteína beta-Amiloide/metabolismo , Animais , Proteínas Relacionadas à Autofagia/metabolismo , Humanos , Peptídeos e Proteínas de Sinalização Intracelular/metabolismo , Camundongos , Camundongos Transgênicos , Neuroblastoma/metabolismo , Doenças Neurodegenerativas/metabolismo , Neurônios/metabolismoRESUMO
Mesenchymal stem cells (MSC) have emerged as a promising tool to treat inflammatory diseases, such as inflammatory bowel disease (IBD), due to their immunoregulatory properties. Frequently, IBD is modeled in mice by using dextran sulfate sodium (DSS)-induced colitis. Recently, the modulation of autophagy in MSC has been suggested as a novel strategy to improve MSC-based immunotherapy. Hence, we investigated a possible role of Pacer, a novel autophagy enhancer, in regulating the immunosuppressive function of MSC in the context of DSS-induced colitis. We found that Pacer is upregulated upon stimulation with the pro-inflammatory cytokine TNFα, the main cytokine released in the inflammatory environment of IBD. By modulating Pacer expression in MSC, we found that Pacer plays an important role in regulating the autophagy pathway in this cell type in response to TNFα stimulation, as well as in regulating the immunosuppressive ability of MSC toward T-cell proliferation. Furthermore, increased expression of Pacer in MSC enhanced their ability to ameliorate the symptoms of DSS-induced colitis in mice. Our results support previous findings that autophagy regulates the therapeutic potential of MSC and suggest that the augmentation of autophagic capacity in MSC by increasing Pacer levels may have therapeutic implications for IBD.
Assuntos
Colite , Doenças Inflamatórias Intestinais , Transplante de Células-Tronco Mesenquimais , Células-Tronco Mesenquimais , Animais , Autofagia , Colite/tratamento farmacológico , Colite/terapia , Citocinas/metabolismo , Sulfato de Dextrana/farmacologia , Modelos Animais de Doenças , Doenças Inflamatórias Intestinais/metabolismo , Transplante de Células-Tronco Mesenquimais/métodos , Células-Tronco Mesenquimais/metabolismo , Camundongos , Fator de Necrose Tumoral alfa/metabolismoRESUMO
BACKGROUND: Amyotrophic lateral sclerosis (ALS) is a multifactorial fatal motoneuron disease without a cure. Ten percent of ALS cases can be pointed to a clear genetic cause, while the remaining 90% is classified as sporadic. Our study was aimed to uncover new connections within the ALS network through a bioinformatic approach, by which we identified C13orf18, recently named Pacer, as a new component of the autophagic machinery and potentially involved in ALS pathogenesis. METHODS: Initially, we identified Pacer using a network-based bioinformatic analysis. Expression of Pacer was then investigated in vivo using spinal cord tissue from two ALS mouse models (SOD1G93A and TDP43A315T) and sporadic ALS patients. Mechanistic studies were performed in cell culture using the mouse motoneuron cell line NSC34. Loss of function of Pacer was achieved by knockdown using short-hairpin constructs. The effect of Pacer repression was investigated in the context of autophagy, SOD1 aggregation, and neuronal death. RESULTS: Using an unbiased network-based approach, we integrated all available ALS data to identify new functional interactions involved in ALS pathogenesis. We found that Pacer associates to an ALS-specific subnetwork composed of components of the autophagy pathway, one of the main cellular processes affected in the disease. Interestingly, we found that Pacer levels are significantly reduced in spinal cord tissue from sporadic ALS patients and in tissues from two ALS mouse models. In vitro, Pacer deficiency lead to impaired autophagy and accumulation of ALS-associated protein aggregates, which correlated with the induction of cell death. CONCLUSIONS: This study, therefore, identifies Pacer as a new regulator of proteostasis associated with ALS pathology.
Assuntos
Esclerose Lateral Amiotrófica/metabolismo , Esclerose Lateral Amiotrófica/patologia , Autofagia/efeitos dos fármacos , Proteínas de Ligação a DNA/metabolismo , Neurônios Motores/metabolismo , Esclerose Lateral Amiotrófica/genética , Animais , Modelos Animais de Doenças , Humanos , Camundongos Transgênicos , Medula Espinal/metabolismo , Medula Espinal/patologia , Superóxido Dismutase/genética , Superóxido Dismutase/metabolismoRESUMO
OBJECTIVE: To determine whether aerobic fitness is more salient than weight status in predicting performance on standardized math and reading tests in fourth- to eighth-grade students. STUDY DESIGN: A cross-sectional study of data abstracted from 11,743 students in 47 public schools. Aerobic fitness was defined by entering the healthy fitness zone of Fitnessgram's Progressive Aerobic Cardiovascular Endurance Run, which has been shown to correlate highly with maximum oxygen consumption. Mixed-effects logistic regression analyses were conducted to model the student-level effect of aerobic fitness status on passing the Nebraska State Accountability (NeSA) math and reading tests after adjusting for body mass index (BMI) percentile, free/reduced lunch status, sex, race, grade level, and school type. RESULTS: After adjustment, aerobically fit students had greater odds of passing the NeSA math and reading tests compared with aerobically unfit students regardless of whether the students received free/reduced lunch; however, the effect of being aerobically fit on the standardized test scores was significantly greater for students not receiving free/reduced lunch. Weight status, as measured by BMI percentile, was not a significant predictor of passing the NeSA math or reading test after including free/reduced lunch status in the model. CONCLUSIONS: Aerobic fitness was a significant predictor of academic performance; weight status was not. Although decreasing BMI for an overweight or obese child undoubtedly improves overall health, results indicated all students benefit academically from being aerobically fit regardless of weight or free/reduced lunch status. Therefore, to improve academic performance, school systems should focus on the aerobic fitness of every student.