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Notch activates cell cycle reentry and progression in quiescent cardiomyocytes
Correspondence to Mark Mercola: mmercola{at}burnham.org
The inability of heart muscle to regenerate by replication of existing cardiomyocytes has engendered considerable interest in identifying developmental or other stimuli capable of sustaining the proliferative capacity of immature cardiomyocytes or stimulating division of postmitotic cardiomyocytes. Here, we demonstrate that reactivation of Notch signaling causes embryonic stem cell–derived and neonatal ventricular cardiomyocytes to enter the cell cycle. The proliferative response of neonatal ventricular cardiomyocytes declines as they mature, such that late activation of Notch triggers the DNA damage checkpoint and G2/M interphase arrest. Notch induces recombination signal-binding protein 1 for J
(RBP-J)-dependent expression of cyclin D1 but, unlike other inducers, also shifts its subcellular distribution from the cytosol to the nucleus. Nuclear localization of cyclin D1 is independent of RBP-J. Thus, the influence of Notch on nucleocytoplasmic localization of cyclin D1 is an unanticipated property of the Notch intracellular domain that is likely to regulate the cell cycle in multiple contexts, including tumorigenesis as well as cardiogenesis.
Abbreviations used in this paper: βGal, β-galactosidase; BIO, 6-bromoindirubin-3'-oxime; CRM1, chromosome region maintenance 1; DBM, DNA-binding mutant; GSK3β, glycogen synthase kinase-3β; Hes1, hairy and enhancer of split 1; His3, histone 3; ICD, intracellular domain; LMB, leptomycin B; mESC, mouse embryonic stem cell; MLC2V, myosin light chain 2V; NMVC, neonatal mouse ventricular cardiomyocyte; NRVC, neonatal rat ventricular cardiomyocyte; P, postnatal day; PHE, phenylephrine; Rb, retinoblastoma protein; RBP-J
, recombination signal-binding protein 1 for J. © 2008 Campa et al. This article is distributed under the terms of an Attribution–Noncommercial–Share Alike–No Mirror Sites license for the first six months after the publication date (see http://www.jcb.org/misc/terms.shtml). After six months it is available under a Creative Commons License (Attribution–Noncommercial–Share Alike 3.0 Unported license, as described at http://creativecommons.org/licenses/by-nc-sa/3.0/).
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