RESUMO
Muscle satellite cells (MuSCs) are the quiescent muscle stem cells required for adult skeletal muscle repair. The impact of environmental stress such as pollution on MuSC behavior remains unexplored. We evaluated the impact of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) exposure, a ubiquitous and highly toxic pollutant, on MuSCs by combining in vivo mouse molecular genetic models with ex vivo studies. While all MuSCs express the transcription factor PAX7, we show that a subset also express PAX3 and exhibit resistance to environmental stress. Upon systemic TCDD treatment, PAX3-negative MuSCs display impaired survival, atypical activation, and sporadic differentiation through xenobiotic aryl hydrocarbon receptor signaling. We further show that PAX3-positive MuSCs become sensitized to environmental stress when PAX3 function is impaired and that PAX3-mediated induction of mTORC1 is required for protection. Our study, therefore, identifies a functional heterogeneity of MuSCs in response to environmental stress controlled by PAX3.
Assuntos
Células-Tronco Adultas/fisiologia , Poluição Ambiental/efeitos adversos , Fator de Transcrição PAX3/metabolismo , Fator de Transcrição PAX7/metabolismo , Dibenzodioxinas Policloradas/efeitos adversos , Células Satélites de Músculo Esquelético/fisiologia , Animais , Diferenciação Celular , Sobrevivência Celular , Células Cultivadas , Alvo Mecanístico do Complexo 1 de Rapamicina/genética , Alvo Mecanístico do Complexo 1 de Rapamicina/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Fator de Transcrição PAX3/genética , Fator de Transcrição PAX7/genética , Receptores de Hidrocarboneto Arílico/metabolismo , Transdução de SinaisRESUMO
State of the art techniques have been developed to isolate and analyze cells from various tissues, aiming to capture their in vivo state. However, the majority of cell isolation protocols involve lengthy mechanical and enzymatic dissociation steps followed by flow cytometry, exposing cells to stress and disrupting their physiological niche. Focusing on adult skeletal muscle stem cells, we have developed a protocol that circumvents the impact of isolation procedures and captures cells in their native quiescent state. We show that current isolation protocols induce major transcriptional changes accompanied by specific histone modifications while having negligible effects on DNA methylation. In addition to proposing a protocol to avoid isolation-induced artifacts, our study reveals previously undetected quiescence and early activation genes of potential biological interest.