title: A differential response to newt regeneration extract by C2C12 and primary mammalian muscle cells.
abstract: BACKGROUND
  Dedifferentiation, a process whereby differentiated cells lose their specialized characteristics and revert to a less differentiated state, plays a key role in the regeneration process in urodele amphibians such as the red spotted newt, Notophthalmus viridescens. Dedifferentiation of fully mature tissues is generally absent in mammalian cells. Previous studies have shown that mouse C2C12 multinucleated myotubes treated with extract derived from regenerating newt forelimbs can re-enter the cell cycle, fragment into mononucleated cells, and proliferate. However, this response has been difficult to replicate.
  
  
  METHODS
  We isolated extract from early newt forelimb regenerates and assessed its effects on differentiation of proliferating primary and C2C12 myoblasts. We also treated fully differentiated primary and C2C12 myotube cultures with extract and assessed cell cycle re-entry and myotube fragmentation.
  
  
  RESULTS
  We have confirmed the results obtained in C2C12 cells and expanded these studies to also examine the effects of newt regeneration extracts on primary muscle cells. Newt extract can block differentiation of both C2C12 and primary myoblasts. Once differentiation is induced, treatment with newt extract causes cell cycle re-entry and fragmentation of C2C12 myotubes. Downregulation of p21 and muscle-specific markers is also induced. Primary myotubes also fragment in response to extract treatment, and the fragmented cells remain viable for long periods of time in culture. However, unlike C2C12 cells, primary muscle cells do not re-enter the cell cycle in response to treatment with newt extracts.
  
  
  CONCLUSIONS
  Dedifferentiation of fully mature muscle occurs during regeneration in the newt forelimb to contribute cells to the regeneration process. Our study shows that extracts derived from regenerating newt forelimbs can induce dedifferentiation, cell cycle re-entry, and fragmentation of mouse C2C12 cells but can only induce fragmentation in primary muscle cells.
authors.affiliation: Ottawa Hospital Research Institute, Vision Research/Regenerative Medicine Program, 501 Smyth Road, Box 307, Ottawa, Ontario K1H 8L6 Canada ; Department of Cellular and Molecular Medicine, University of Ottawa, 451 Smyth Road, Ottawa, Ontario K1H 8M5 Canada.
authors.forename: Sarah
authors.initials: S
authors.lastname: Kawesa
authors.affiliation: Ottawa Hospital Research Institute, Vision Research/Regenerative Medicine Program, 501 Smyth Road, Box 307, Ottawa, Ontario K1H 8L6 Canada ; Department of Cellular and Molecular Medicine, University of Ottawa, 451 Smyth Road, Ottawa, Ontario K1H 8M5 Canada ; Current address: Children's Hospital of Eastern Ontario Research Institute, 401 Smyth Road, Ottawa, Ontario K1H 8L1 Canada.
authors.forename: Jason
authors.initials: J
authors.lastname: Vanstone
authors.affiliation: Ottawa Hospital Research Institute, Vision Research/Regenerative Medicine Program, 501 Smyth Road, Box 307, Ottawa, Ontario K1H 8L6 Canada ; Department of Cellular and Molecular Medicine, University of Ottawa, 451 Smyth Road, Ottawa, Ontario K1H 8M5 Canada.
authors.forename: Catherine
authors.initials: C
authors.lastname: Tsilfidis
keywords: C2C12; Dedifferentiation; Myoblasts; Myotubes; Newt forelimb regeneration