E2F4 is required for cardiomyocyte proliferation.
OBJECTIVE
Although the fundamental role of the E2F transcription factor family in cell proliferation is well established, the specific function of E2F4 is unclear. On the basis of findings from cell culture experiments, E2F4 is generally considered as an inhibitor of cell proliferation. Accumulating evidence suggests, however, that E2F4 acts as an activator of cell proliferation in certain contexts. Here, we have investigated the role of E2F4 during heart development and in proliferating cardiomyocytes.


RESULTS
Nuclear E2F4 expression in cardiomyocytes declined during mouse heart development, which correlates with the loss of proliferative capacity of cardiomyocytes. Re-induction of proliferation in postnatal cardiomyocytes increased nuclear E2F4 expression. E2F4 accumulated in the nucleus at the end of the S phase, remained nuclear during mitosis, and disappeared at the end of cytokinesis. siRNA-mediated inhibition of E2F4 in proliferating postnatal cardiomyocytes resulted in a significant reduction in mitosis, but not in DNA synthesis. Co-staining of E2F4 and Crest revealed that E2F4 co-localizes with kinetochores. Moreover, chromatin immunoprecipitation showed that E2F4 binds to centromeric alpha-satellite DNA during mitosis.


CONCLUSIONS
Our data indicate that E2F4 is required for cardiomyocyte proliferation and suggest a function for E2F4 in mitosis.
van Amerongen
Machteld J
MJ
Department of Cardiac Development and Remodelling, Excellence Cluster Cardio-Pulmonary System, Max-Planck-Institute for Heart and Lung Research, Parkstrasse 1, Bad Nauheim 61231, Germany.
Diehl
Florian
F
Novoyatleva
Tatyana
T
Patra
Chinmoy
C
Engel
Felix B
FB
D000818:Animals; D002453:Cell Cycle / Q000502:physiology; D002455:Cell Division / Q000502:physiology; D002467:Cell Nucleus / Q000378:metabolism; D002478:Cells, Cultured; D050703:E2F2 Transcription Factor / Q000235:genetics / Q000378:metabolism; D050704:E2F4 Transcription Factor / Q000235:genetics* / Q000378:metabolism; D005260:Female; D018507:Gene Expression Regulation, Developmental; D049452:Green Fluorescent Proteins / Q000235:genetics; D006321:Heart / Q000196:embryology*; D006801:Humans; D018386:Kinetochores / Q000502:physiology; D007763:Lac Operon; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D008938:Mitosis / Q000502:physiology; D032383:Myocytes, Cardiac / Q000166:cytology* / Q000502:physiology*; D011247:Pregnancy; D051381:Rats; D017207:Rats, Sprague-Dawley
D050703:E2F2 Transcription Factor; D050704:E2F4 Transcription Factor; C493762:E2F4 protein, human; C484940:E2f2 protein, mouse; C493763:E2f4 protein, mouse; D049452:Green Fluorescent Proteins