Muscle stem cell quiescence and heterogeneity

• Applicants: Professorin Dr. Carmen Birchmeier; Professorin Dr. Simone Spuler
• Subject Area: Cell Biology ; Developmental Biology
• Term: from 2015 to 2020
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 283716387

• Final Report Year: 2022

Final Report Abstract

Define the molecular basis of muscle stem cell quiescence and heterogeneity. Satellite cells, the stem cells of the adult skeletal muscle, provide the cellular source for muscle regeneration. While highly proliferative during early postnatal muscle growth, satellite cells become quiescent in the adult to preserve their functions via this stress resistant state. In response to injury, satellite cells are activated and generate myoblasts for muscle repair, but a subpopulation self-renews to form new quiescent stem cells. Importantly, satellite cells show heterogeneity, with a part of them presenting with high self-renewal and regenerative capacities. Here we joined efforts of French and German teams to identify the molecular mechanisms allowing the establishment and maintenance of quiescence in satellite cells and during muscle regeneration. Furthermore, we characterized satellite cell heterogeneity to define the poorly understood resilient stem cell subpopulation that possesses high regenerative capacity. This project improves basic knowledge on muscle stem cells, with the potential to contribute to the development of therapies that rely on such cells. High throughput sequencing, innovative live imaging and mouse molecular genetics to clarify satellite cell quiescence and heterogeneity. The project relied on a series of in vitro and genetic approaches to characterize the quiescence and heterogeneity of satellite cells. Firstly, to identify the native state of quiescence in vivo, we developed methods that allowed accurate sequencing, including at the single cell level, overcoming common technical artefacts induced by standard high throughput procedures. To prove the involvement of specific molecular targets in the quiescence regulation, we monitored the effects of genetically deleting these factors using transgenic mouse lines. In a complementary analysis, we did transplantation experiments with muscle-derived cells lacking signalling components of the satellite cell lineage. Finally, we employed innovative live imaging in cultured satellite cell-derived myoblasts to monitor oscillatory activity of key transcription factors and analyse their contribution to satellite cell heterogeneity. Combining fine in vitro and in vivo approaches we identified key molecular regulators of satellite cell quiescence and heterogeneity and we dissected their role for these states. Result highlights. We finely characterized the true molecular signature of satellite cell quiescence. Based on such large-scale data we identified stem cell-regulating and cell cycle-associated factors with a potential to regulate satellite cell quiescence and proved their relevance to quiescence and self-renewal via loss-of-function genetic approaches. Furthermore, we proved the relevance of other muscle-derived cells to efficiently regenerate skeletal muscle. Finally, we showed that oscillatory changes in gene expression contributes to satellite cell heterogeneity with important functional outcomes.

Publications

• Heterochromatin compaction is regulated by Suv4-20h1 to maintains skeletal muscle stem cells quiescence. Stem Cell Investig. 2016. 3:23
  Machado L, Relaix F
  
• Cellular localization of the cell cycle inhibitor Cdkn1c controls growth arrest of adult skeletal muscle stem cells. Elife. 2018. 7. pii: e33337
  Mademtzoglou D, Asakura Y, Borok MJ, Alonso-Martin S, Mourikis P, Kodaka Y, Mohan A, Asakura A, Relaix F
  
• In situ fixation redefines quiescence and early activation of skeletal muscle stem cells. Cell Rep. 2018. 21(7):1982
  Machado L, Esteves de Lima J, Fabre O, Proux C, Legendre R, Szegedi A, Varet H, Ingerslev LR, Barrès R, Relaix F, Mourikis P
  
• SOXF factors regulate murine satellite cell self-renewal and function through inhibition of βcatenin activity. Elife. 2018. 7. pii: e26039
  Alonso-Martin S, Auradé F, Mademtzoglou D, Rochat A, Zammit PS, Relaix F
  
• 240th ENMC workshop: The involvement of skeletal muscle stem cells in the pathology of muscular dystrophies 25-27 January 2019, Hoofddorp, The Netherlands. Neuromuscul Disord. 2019. 29(9):704-715
  Morgan J, Butler-Browne G, Muntoni F, Patel K; Amthor H, Birchmeier C, Bonaldo P, Bönnemann C, Chaturvedi D, Davenport R, Ferreiro A, Furling D, Giordani L, Grounds M, Jungbluth H, Muñoz-Cánoves P, Mishra P, Padberg G, Paradas C, Partridge T, Relaix F, Rüegg M, Stevenson A, Van Putten M, Wood A, Zammit P
  
• Oscillations of MyoD and Hes1 proteins regulate the maintenance of activated muscle stem cells. Genes Dev. 2019. 33(9-10):524-535
  Lahmann I, Bröhl D, Zyrianova T, Isomura A, Czajkowski MT, Kapoor V, Griger J, Ruffault PL, Mademtzoglou D, Zammit PS, Wunderlich T, Spuler S, Kühn R, Preibisch S, Wolf J, Kageyama R, Birchmeier C