title: Asymmetric chromatid segregation in cardiac progenitor cells is enhanced by Pim-1 kinase.
abstract: BACKGROUND
  Cardiac progenitor cells (CPCs) in the adult heart are used for cell-based treatment of myocardial damage, but factors determining stemness, self-renewal, and lineage commitment are poorly understood. Immortal DNA strands inherited through asymmetric chromatid segregation correlate with self-renewal of adult stem cells, but the capacity of CPCs for asymmetric segregation to retain immortal strands is unknown. Cardioprotective kinase Pim-1 increases asymmetric cell division in vivo, but the ability of Pim-1 to enhance asymmetric chromatid segregation is unknown.
  
  
  OBJECTIVE
  We aimed to demonstrate immortal strand segregation in CPCs and the enhancement of asymmetric chromatid distribution by Pim-1 kinase.
  
  
  RESULTS
  Asymmetric segregation is tracked by incorporation of bromodeoxyuridine. The CPC DNA was labeled for several generations and then blocked in second cytokinesis during chase to determine distribution of immortal versus newly synthesized strands. Intensity ratios of binucleated CPCs with bromodeoxyuridine of ≥70:30 between daughter nuclei indicative of asymmetric chromatid segregation occur with a frequency of 4.57, and asymmetric chromatid segregation is demonstrated at late mitotic phases. Asymmetric chromatid segregation is significantly enhanced by Pim-1 overexpression in CPCs (9.19 versus 4.79 in eGFP-expressing cells; P=0.006).
  
  
  CONCLUSIONS
  Asymmetric segregation of chromatids in CPCs is increased nearly two-fold with Pim-1 kinase overexpression, indicating that Pim-1 promotes self-renewal of stem cells.
authors.affiliation: SDSU Heart Institute and Biology Department, San Diego State University, CA 92182, USA.
authors.forename: Balaji
authors.initials: B
authors.lastname: Sundararaman
authors.forename: Daniele
authors.initials: D
authors.lastname: Avitabile
authors.forename: Mathias H
authors.initials: MH
authors.lastname: Konstandin
authors.forename: Christopher T
authors.initials: CT
authors.lastname: Cottage
authors.forename: Natalie
authors.initials: N
authors.lastname: Gude
authors.forename: Mark A
authors.initials: MA
authors.lastname: Sussman
mesh_terms: D000818:Animals; D001973:Bromodeoxyuridine / Q000378:metabolism; D049109:Cell Proliferation; D002478:Cells, Cultured; D002842:Chromatids / Q000378:metabolism*; D020090:Chromosome Segregation; D048749:Cytokinesis; D004261:DNA Replication; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D006801:Humans; D051379:Mice; D008938:Mitosis; D032383:Myocytes, Cardiac / Q000201:enzymology*; D051573:Proto-Oncogene Proteins c-pim-1 / Q000235:genetics / Q000378:metabolism*; D013234:Stem Cells / Q000201:enzymology*; D014162:Transfection
chemical_list: C485184:enhanced green fluorescent protein; D049452:Green Fluorescent Proteins; C496634:PIM1 protein, human; D051573:Proto-Oncogene Proteins c-pim-1; D001973:Bromodeoxyuridine