Document Detail


Down-regulation of replication factor C-40 (RFC40) causes chromosomal missegregation in neonatal and hypertrophic adult rat cardiac myocytes.
MedLine Citation:
PMID:  22720015     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
BACKGROUND: Adult mammalian cardiac myocytes are generally assumed to be terminally differentiated; nonetheless, a small fraction of cardiac myocytes have been shown to replicate during ventricular remodeling. However, the expression of Replication Factor C (RFC; RFC140/40/38/37/36) and DNA polymerase δ (Pol δ) proteins, which are required for DNA synthesis and cell proliferation, in the adult normal and hypertrophied hearts has been rarely studied.
METHODS: We performed qRT-PCR and Western blot analysis to determine the levels of RFC and Pol δ message and proteins in the adult normal cardiac myocytes and cardiac fibroblasts, as well as in adult normal and pulmonary arterial hypertension induced right ventricular hypertrophied hearts. Immunohistochemical analyses were performed to determine the localization of the re-expressed DNA replication and cell cycle proteins in adult normal (control) and hypertrophied right ventricle. We determined right ventricular cardiac myocyte polyploidy and chromosomal missegregation/aneuploidy using Fluorescent in situ hybridization (FISH) for rat chromosome 12.
RESULTS: RFC40-mRNA and protein was undetectable, whereas Pol δ message was detectable in the cardiac myocytes isolated from control adult hearts. Although RFC40 and Pol δ message and protein significantly increased in hypertrophied hearts as compared to the control hearts; however, this increase was marginal as compared to the fetal hearts. Immunohistochemical analyses revealed that in addition to RFC40, proliferative and mitotic markers such as cyclin A, phospho-Aurora A/B/C kinase and phospho-histone 3 were also re-expressed/up-regulated simultaneously in the cardiac myocytes. Interestingly, FISH analyses demonstrated cardiac myocytes polyploidy and chromosomal missegregation/aneuploidy in these hearts. Knock-down of endogenous RFC40 caused chromosomal missegregation/aneuploidy and decrease in the rat neonatal cardiac myocyte numbers.
CONCLUSION: Our novel findings suggest that transcription of RFC40 is suppressed in the normal adult cardiac myocytes and its insufficient re-expression may be responsible for causing chromosomal missegregation/aneuploidy and in cardiac myocytes during right ventricular hypertrophy.
Authors:
Hirotaka Ata; Deepa Shrestha; Masahiko Oka; Rikuo Ochi; Chian Ju Jong; Sarah Gebb; John Benjamin; Stephen Schaffer; Holly H Hobart; James Downey; Ivan McMurtry; Rakhee Gupte
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2012-06-14
Journal Detail:
Title:  PloS one     Volume:  7     ISSN:  1932-6203     ISO Abbreviation:  PLoS ONE     Publication Date:  2012  
Date Detail:
Created Date:  2012-06-21     Completed Date:  2012-12-13     Revised Date:  2013-07-12    
Medline Journal Info:
Nlm Unique ID:  101285081     Medline TA:  PLoS One     Country:  United States    
Other Details:
Languages:  eng     Pagination:  e39009     Citation Subset:  IM    
Affiliation:
Biochemistry & Molecular Biology, University of South Alabama, Mobile, Alabama, United States of America.
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MeSH Terms
Descriptor/Qualifier:
Animals
Animals, Newborn
Cardiomegaly / metabolism*,  pathology
Cells, Cultured
Chromosomes*
DNA Polymerase III / metabolism
Down-Regulation*
Immunohistochemistry
In Situ Hybridization, Fluorescence
Male
Myocardium / cytology,  metabolism*
Rats
Rats, Sprague-Dawley
Real-Time Polymerase Chain Reaction
Replication Protein C / metabolism*
Chemical
Reg. No./Substance:
0/Replication Protein C; EC 2.7.7.-/DNA Polymerase III
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