During neonatal development, cardiac myocytes undergo a transition from hyperplastic to hypertrophic growth. Whether these cells are terminally differentiated and permanently withdrawn from the cell cycle shortly after birth is controversial. Nevertheless, the clinical observation that functionally significant myocardial regeneration has not been documented in cardiovascular disease or injury during adulthood seems to support the notion that the vast majority of cardiac myocytes do not proliferate once they differentiate. Regardless of the controversy, the elucidation on how mitosis is blocked in cardiac myocytes may facilitate development of new cardiovascular therapies, based on the regeneration of the adult myocardium. To better understand postnatal myocardial development, we performed suppression subtractive hybridization to isolate genes that are differentially expressed in day one or day seven postnatal rat ventricular myocardium. Here we report the down-regulated mRNA expression of the 40-kDa subunit of replication factor C (RFC p40 or RFC2), which is an essential processive factor for proliferating cellular nuclear antigen-dependent DNA replication during neonatal myocardial development.
Copyright 2000 Wiley-Liss, Inc.