Annexin expressions are temporally and spatially regulated during rat hepatocyte differentiation

Annexin (Anx) 1, 2,5, and, 6 expressions were determined at the transcripti onal and translational levels in the rat hepatocytes, from gestational day 15 to postnatal day 17. Dramatic shifts were observed in Anx 1 and 2 levels , which peaked at day 1 and gestational day 20, respectively, and reached l ow levels thereafter. However, Aux 5 and 6 rates were more constant. Prenat al administration of dexamethasone (dex) resulted in a decrease of Anx 1 mR NA levels, and a strong increase in Anx 2 mRNA contents. In adult hepatocyt es cultured in the presence of EGF or HGF, Anx 1 and 2 expressions resumed. By immunohistochemistry, Anx 1 was detected only in the cytoplasm of hepat ocytes of 1- to 3-day-old rats, Anx 2 and 6 both exhibited a redistribution from the cytoplasm toward the plasma membrane, and Anx 5 was present in th e nucleus, cytoplasm, and plasma membrane. Thus, Anx 1, 2, 5, and 6 have in dividual modes of expression and localization in the differentiating hepato cytes, where they might play unique roles at well defined phases of liver o ntogeny. (C) 2001 Wfley-Liss, Inc.