RESUMO
Molecular mechanisms underlying sarcopenia, the age-related loss of skeletal muscle mass and function, remain unclear. To identify molecular changes that correlated best with sarcopenia and might contribute to its pathogenesis, we determined global gene expression profiles in muscles of rats aged 6, 12, 18, 21, 24, and 27 months. These rats exhibit sarcopenia beginning at 21 months. Correlation of the gene expression versus muscle mass or age changes, and functional annotation analysis identified gene signatures of sarcopenia distinct from gene signatures of aging. Specifically, mitochondrial energy metabolism (e.g., tricarboxylic acid cycle and oxidative phosphorylation) pathway genes were the most downregulated and most significantly correlated with sarcopenia. Also, perturbed were genes/pathways associated with neuromuscular junction patency (providing molecular evidence of sarcopenia-related functional denervation and neuromuscular junction remodeling), protein degradation, and inflammation. Proteomic analysis of samples at 6, 18, and 27 months confirmed the depletion of mitochondrial energy metabolism proteins and neuromuscular junction proteins. Together, these findings suggest that therapeutic approaches that simultaneously stimulate mitochondrogenesis and reduce muscle proteolysis and inflammation have potential for treating sarcopenia.
Assuntos
Envelhecimento/genética , Mitocôndrias/metabolismo , Junção Neuromuscular/patologia , Proteoma/análise , Sarcopenia/patologia , Transcriptoma , Envelhecimento/metabolismo , Animais , DNA Mitocondrial/genética , Metabolismo Energético , Perfilação da Expressão Gênica , Imuno-Histoquímica , Modelos Lineares , Masculino , Análise em Microsséries , Mitocôndrias/genética , Mitocôndrias/patologia , Força Muscular/genética , Músculo Esquelético/metabolismo , Músculo Esquelético/patologia , Junção Neuromuscular/genética , Junção Neuromuscular/metabolismo , Mudanças Depois da Morte , Proteômica , Ratos , Ratos Sprague-Dawley , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Transdução de Sinais , Regulação para CimaRESUMO
The search for novel therapeutic interventions for viral disease is a challenging pursuit, hallmarked by the paucity of antiviral agents currently prescribed. Targeting of viral proteins has the inextricable challenge of rise of resistance. Safe and effective vaccines are not possible for many viral pathogens. New approaches are required to address the unmet medical need in this area. We undertook a cell-based high-throughput screen to identify leads for development of drugs to treat respiratory syncytial virus (RSV), a serious pediatric pathogen. We identified compounds that are potent (nanomolar) inhibitors of RSV in vitro in HEp-2 cells and in primary human bronchial epithelial cells and were shown to act postentry. Interestingly, two scaffolds exhibited broad-spectrum activity among multiple RNA viruses. Using the chemical matter as a probe, we identified the targets and identified a common cellular pathway: the de novo pyrimidine biosynthesis pathway. Both targets were validated in vitro and showed no significant cell cytotoxicity except for activity against proliferative B- and T-type lymphoid cells. Corollary to this finding was to understand the consequences of inhibition of the target to the host. An in vivo assessment for antiviral efficacy failed to demonstrate reduced viral load, but revealed microscopic changes and a trend toward reduced pyrimidine pools and findings in histopathology. We present here a discovery program that includes screen, target identification, validation, and druggability that can be broadly applied to identify and interrogate other host factors for antiviral effect starting from chemical matter of unknown target/mechanism of action.