Mammalian postmitotic nuclei reenter the cell cycle after serum stimulation in newt/mouse hybrid myotubes.
Cell cycle reentry and dedifferentiation of postmitotic cells are important aspects of the ability of an adult newt and other urodele amphibians to regenerate various tissues and appendages [1]. In contrast to their mammalian counterparts, newt A1 myotubes are able to reenter S phase after serum stimulation of a pathway leading to phosphorylation of the retinoblastoma protein, pRb [2]. The activity in serum is not due to mitogenic growth factors but is generated indirectly by the activation of thrombin and subsequent proteolysis [3]. In this paper we describe the formation of interspecies hybrid (heterokaryon) myotubes by the fusion of mouse C2C12 [4] and newt A1 [5, 6] myogenic cells. The C2C12 nuclei reenter the cell cycle upon serum stimulation of the hybrids, while C2C12 homokaryon myotubes remain arrested under these conditions. These findings indicate that the postmitotic arrest of the mouse nuclei is undermined by the pathway activated in the newt cytoplasm. The hybrid myotubes provide a new model for the manipulation of the postmitotic arrest in both mammalian and newt differentiated cells.
Velloso
C P
CP
Department of Biochemistry and Molecular Biology, University College London, Gower Street, WC1E 6BT, London, United Kingdom.
Simon
A
A
Brockes
J P
JP
D000818:Animals; D002453:Cell Cycle; D002454:Cell Differentiation; D003470:Culture Media; D006822:Hybrid Cells / Q000166:cytology*; D051379:Mice / Q000502:physiology*; D018485:Muscle Fibers, Skeletal / Q000166:cytology*; D012038:Regeneration; D016196:S Phase; D012455:Salamandridae / Q000502:physiology*; D013045:Species Specificity
D003470:Culture Media