Different signal transduction by epidermal growth factor may be responsible for the difference in modulation of amino acid transport between fetal and adult hepatocytes
✍ Scribed by S. Leoni; S. Spagnuolo; M. Marino; F. Terenzi; M. Massimi; L. Conti Devirgiliis
- Publisher
- John Wiley and Sons
- Year
- 1993
- Tongue
- English
- Weight
- 695 KB
- Volume
- 155
- Category
- Article
- ISSN
- 0021-9541
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✦ Synopsis
0018.5
Rome, /ta/y 11 -'"C1-2-aminoisobutyric acid (AIB) uptake and signal transduction pattern after epidermal growth factor (EGF) stimulation were examined in freshly isolated hepatocytes from 20-day-old fetuses and 3-month-old rats. EGF induced a transient increase of AIB transport after 10 min only in adult animals; the observed unresponsiveness of fetal liver is not dependent on a lack of EGF receptors which are present though to a lesser extent on the plasma membrane in this period. As far as the production of the second messengers, inositol trisphosphate (IP,) and calcium, is concerned, substantial differences were found: EGF increased IP, production in adult hepatocytes, whereas it had no effect in fetal ones. Moreover, the addition of EGF induced a calcium transient in hepatocytes from adult animals, while there was no increase in fetal cells. The lack of EGF effect o n amino acid transport in fetal cells could be due to its inability to produce both IP, and calcium transients, suggesting that this transduction pathway is not activated during fetal life. o 1993 WiIey-Liss, Inc.