Expression of replication factor C 40-kDa subunit is down-regulated duringneonatal development in rat ventricular myocardium

During neonatal development, cardiac myocytes undergo a transition from hyp erplastic to hypertrophic growth. Whether these cells are terminally differ entiated and permanently withdrawn from the cell cycle shortly after birth is controversial.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 cardiovascul ar disease or injury during adulthood seems to support the notion that the vast majority of cardiac myocytes do not proliferate once they differentiat e. Regardless of the controversy, the elucidation on how mitosis is blocked in cardiac myocytes may facilitate development of new cardiovascular thera pies, based on the regeneration of the adult myocardium. To better understa nd postnatal myocardial development, we performed suppression subtractive h ybridization 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 (RF C p40 or RFC2), which is an essential processive factor for proliferating c ellular nuclear antigen-dependent DNA replication during neonatal myocardia l development. J. Cell. Biochem. 78:533-540, 2000. (C) 2000 Wiiey-Liss, Inc .