The beta 1,4-galactosyltransferase gene is post-transcriptionally regulated during differentiation of mouse F9 teratocarcinoma cells.

Abstract

Mouse F9 teratocarcinoma cells converted into primitive endoderm and parietal endoderm-like cells when treated with retinoic acid (RA) and RA plus dibutyryl cyclic AMP (dbtcAMP), respectively. The carbohydrate chains of glycoconjugates are known to undergo rapid changes during F9 cell differentiation. The mechanism of gene regulation of beta 1,4-galactosyltransferase (beta 1,4GalT), one of the glycosyltransferases involved in the synthesis of carbohydrate structures, was explored during the differentiation of F9 cells. Northern blot analysis revealed that the amount of beta 1,4GalT mRNA increased approximately 1.5- and 6.5-fold in response to treatment with RA alone and RA plus dbtcAMP (RA/dbtcAMP), respectively, for 8 days. beta 1,4GalT specific activity also gradually increased up to 21-fold in response to treatment with RA/dbtcAMP for 8 days. The reason for the different rates of increase in mRNA and enzyme activity remains to be determined. The transcriptional activity of the beta 1,4GalT gene was measured during the course of RA/dbtcAMP-induced F9 cell differentiation in transient transfection experiments using 5'-upstream region DNA (1.8 kb) of the mouse beta 1,4GalT gene combined with luciferase cDNA. Although activity was slightly enhanced on the first day after induction, no significant rise in transcriptional activity was observed in the late stage of induction (3-6 days), when mRNA levels were greatly increased. This was further supported by the nuclear run-off assay which indicated that the rate of de novo synthesis of the beta 1,4GalT gene transcript in the RA/dbtcAMP-induced cells was almost the same as in undifferentiated F9 cells.(ABSTRACT TRUNCATED AT 250 WORDS)