days of age, the hepatic 514 gene is transcriptionally inactive, mRNAs14 levels ... unknown, a body of circumstantial data points to a role in ... at 20-22 days postpartum and the accompanying site-specific changes in ..... represent the number of separate determinations. ... The results in the table are not corrected for probe ...
THEJOURNAL OF BIOLOGICAL CHEMISTRY 0 1988by The American Society for Biochemistry and Molecular Biology, Inc.
Vol. 263, No. 15, Issue of May 25, pp. 7254-7260.1988 Printed in U.S.A.
Transcriptional Activation of the Rat LiverS14 Gene during Postnatal Development* (Received for publication, July 1, 1987)
Donald B. Jump$, AndrewVeit, Vivian Santiago, Gerald Lepar, and Larry Herberholz From the Department of Physiology, Michigan State University, East Lansing, Michigan 48824
The mRNA coding for the rat liver 514 protein (Mr levels of the mRNA (liver and lactating mammary gland). 17,000,PI 4.9)shows profound increases during post- The presence of a DNase I hypersensitive site near the 5’ end
natal development. In an effort to define molecular the of the S14 gene, designated Hss-1, correlates with high levels basis for the postnatal rise in mRNASl4we examined of mRNASl4expression in liver and lactatingmammary gland. the chromatin organization of the 514 gene, its DNA A second DNase I hypersensitive site located 1.3kb’ upstream methylation state, the hepatic expression of mRNASl4, from the S14 cap site (Hss-2) in liver and mammary gland is and the in vitro 514 “run-on” activity prior to and also found in kidney, a tissue in which mRNAsl, expression after weaning a t 21 days postpartum. In animals 515 is 4 % of that found in liver. Thus, the presence of Hss-1 days of age, the hepatic 514 gene is transcriptionally only in liver and lactating mammary gland implicates this inactive, mRNAs14 levels are 50.5% of adult levels, region as an important structural component for the tissueand the chromatin organization within 11 kilobases of specific expression of the S14 gene (6). Modification of the the 5’end of the 514 gene is similar to that found in nucleosomal packaging at or near the 5’ end of a gene is a tissues not expressing mRNAs14. From 18 to 22 days requisite step for the activation of gene transcription (7, 8). postpartum, the transcriptional activity of the 514 Such modification of chromatin structure is postulated to gene increases 240-fold and mRNAs14increases 2100- enhance the accessibility of important DNA sequences to fold approaching adult levels of expression.Highly specific changes in 514 chromatin structure accom- regulatory proteins involved in gene transcription. The patpany gene activation. The formationof Hss-1 near the tern of chromatin structure, DNA methylation, and expres514 cap site (-65 to -265 base pairs) and Hss-3-3.3 sion of mRNAS14reported for the S14 gene is similar to that kilobases upstream fromthe 514 cap site suggests that described for many genes subject to tissue-specific regulation changes in DNA-protein interaction at these sites may (7-13). function in both the tissue-specific and developmental With this background we were surprised to find that Hss-1 was absent and the S14 gene was hypermethylated in livers regulation of 514 gene expression. The methylation studies suggest HhaI sites may be a cue for thetissue- obtained from 15-day-old rats.’ A previous report demonspecific expressionof 514. However, the maintenance strated the S14 gene was fully transcriptionally active by 15 of hypermethylated HpaII sites throughout 514 gene days of age (4) even though hepatic mRNAs14levelswere
