BACKGROUND/AIMS: The pattern of nucleoside transporter expression in hepatocytes was studied in the developing rat liver. METHODS: Hepatocytes isolated from fetuses, neonates and adult rats were used for uridine uptake measurements and concentrative nucleoside transporter (CNT) expression. RESULTS: Adult hepatocytes showed the highest Na-dependent uridine uptake, but fetal hepatocytes exhibited a significant NBTI-sensitive component of equilibrative Na+-independent transport, which was either negligible or absent in neonatal and adult rat hepatocytes. Low Na+-dependent uridine uptake was associated with low amounts of CNT1 and CNT2 transporter proteins, both with apparent Km values in the low micromolar range. Hepatocyte primary cultures from 20-day-old fetuses showed very low amounts of CNT2 mRNA, and expressed both carrier proteins. Incubation of fetal hepatocytes with dexamethasone and T3 resulted in a significant increase in Na+-dependent uridine uptake and an accumulation of the CNT2 protein and mRNA. CONCLUSIONS: The expression of concentrative nucleoside carriers in hepatocytes from developing rat liver is developmentally regulated. Addition of endocrine factors known to induce differentiation of fetal hepatocytes results in selective up-regulation of CNT2 expression.
BACKGROUND/AIMS: The pattern of nucleoside transporter expression in hepatocytes was studied in the developing rat liver. METHODS: Hepatocytes isolated from fetuses, neonates and adult rats were used for uridine uptake measurements and concentrative nucleoside transporter (CNT) expression. RESULTS: Adult hepatocytes showed the highest Na-dependent uridine uptake, but fetal hepatocytes exhibited a significant NBTI-sensitive component of equilibrative Na+-independent transport, which was either negligible or absent in neonatal and adult rat hepatocytes. Low Na+-dependent uridine uptake was associated with low amounts of CNT1 and CNT2 transporter proteins, both with apparent Km values in the low micromolar range. Hepatocyte primary cultures from 20-day-old fetuses showed very low amounts of CNT2 mRNA, and expressed both carrier proteins. Incubation of fetal hepatocytes with dexamethasone and T3 resulted in a significant increase in Na+-dependent uridine uptake and an accumulation of the CNT2 protein and mRNA. CONCLUSIONS: The expression of concentrative nucleoside carriers in hepatocytes from developing rat liver is developmentally regulated. Addition of endocrine factors known to induce differentiation of fetal hepatocytes results in selective up-regulation of CNT2 expression.
Authors: F J Casado; M P Lostao; I Aymerich; I M Larráyoz; S Duflot; S Rodríguez-Mulero; M Pastor-Anglada Journal: J Physiol Biochem Date: 2002-12 Impact factor: 4.158
Authors: Jing Zhang; Tracey Tackaberry; Mabel W L Ritzel; Taylor Raborn; Gerry Barron; Stephen A Baldwin; James D Young; Carol E Cass Journal: Biochem J Date: 2006-03-01 Impact factor: 3.857
Authors: Concepció Soler; Antonio Felipe; José García-Manteiga; Maria Serra; Elena Guillén-Gómez; F Javier Casado; Carol MacLeod; Manuel Modolell; Marçal Pastor-Anglada; Antonio Celada Journal: Biochem J Date: 2003-11-01 Impact factor: 3.857