K. Fukuda et al., DEVELOPMENTAL-CHANGES OF DNA METHYLATION PATTERN OF EMBRYONIC CHICK PEPSINOGEN GENE, Journal of Biochemistry, 115(3), 1994, pp. 502-506
Embryonic chick pepsinogen (ECPg) is one of the pepsinogen isozymogens
and its expression is restricted to epithelial cells of the embryonic
chick proventriculus (glandular stomach). To examine whether DNA meth
ylation is involved in the regulation of organ-specific and developmen
tal stage-specific expression of ECPg gene, we analyzed the extent of
methylation of EGPg gene in normal embryonic and hatched chick organs
using methylation-sensitive restriction enzymes. In the proventriculus
some CCGG sites underwent demethylation in the gene region after the
onset of transcription of the ECPg gene. By contrast, these sites were
kept methylated throughout the development in the other organs which
do not express ECPg gene. GCGC sites in the gene region became methyla
ted in organs which do not express the ECPg gene, after the initiation
of transcription of the ECPg gene in the proventriculus. In the prove
ntriculus, GCGC sites, which were methylated in other organs, were kep
t unmethylated throughout the development. The methylation state of Cp
G: sites showed no change in the proventriculus of a chick 2 weeks aft
er hatching when the expression of the ECPg gene had completely ceased
. The data presented here demonstrate that the DNA methylation is invo
lved in the regulation of organ-specific expression, but stage-specifi
c expression might be brought about by some other mechanisms.