RESUMO
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
CBA/J mice are resistant to Leishmania major infection but are permissive to L. amazonensis infection. In addition, CBA/J macrophages control L. major but not L. amazonensis infection in vitro. Phagocytosis by macrophages is known to determine the outcome of Leishmania infection. Pattern recognition receptors (PRR) adorning antigen presenting cell surfaces are known to coordinate the link between innate and adaptive immunity. The macrophage receptor with collagenous structure (MARCO) is a PRR that is preferably expressed by macrophages and is capable of binding Gram-positive and Gram-negative bacteria. No research on the role of MARCO in Leishmania-macrophage interactions has been reported. Here, we demonstrate, for the first time, that MARCO expression by CBA/J macrophages is increased in response to both in vitro and in vivo L. major infections, but not to L. amazonensis infection. In addition, a specific anti-MARCO monoclonal antibody reduced L. major infection of macrophages by 30%-40% in vitro. The draining lymph nodes of anti-MARCO-treated mice displayed a reduced presence of immunolabelled parasite and parasite antigens, as well as a reduced inflammatory response. These results support the hypothesis that MARCO has a role in macrophage infection by L. major in vitro as well as in vivo.