Thyroid hormone and circadian regulation of the binding activity of a liver-specific protein associated with the 5‵-flanking region of the S14 gene

N C W Wong,A M Perez-Castillo,M M Sanders,H L Schwartz,J H Oppenheimer

doi:10.1016/s0021-9258(18)83766-8

N C W Wong, A M Perez-Castillo + Show 3 more

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https://doi.org/10.1016/s0021-9258(18)83766-8

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Abstract

Recent studies have described a DNase I hypersensitive site in the 5'-flanking region of the rat hepatic S14 gene that is closely associated with its expression. A 111-base pair subfragment (-389 to -279) of this region interacts specifically in a gel shift assay with a protein present in hepatic nuclear protein extracts. This protein, designated P1, was not present in extracts of other tissues, even those in which the gene is expressed and hormonally regulated. The binding activity of P1 is exceedingly low in extracts from hypothyroid rats and is markedly increased by administration of thyroid hormone. However, the slow accumulation of P1 after thyroid hormone administration indicates that increased levels of P1 are not necessary for the acute hormonal induction of S14 gene expression. The level of P1 binding activity increases in the evening, synchronous with circadian variation of hepatic mRNA S14. Since neither P1 binding activity nor circadian variation in mRNA-S14 levels are observed in the other tissues expressing the S14 gene, P1 may function to modulate the circadian rhythm observed in hepatic S14 gene expression. DNase I footprinting analysis revealed that P1 binds to a defined nucleotide sequence, 5'-AAAAGAGCTATTGATTGCCTGCA-3', located between -310 and -288 in the S14 gene.

Highlights

Recent studies have described a DNase I hypersen- tissues of the rat, including lactating mammary gland and sitive site in the 6”flanking region of the rat hepatic white and brown adipose tissue
Since neither P1 binding activity HS-1 revealed that a protein present in hepatic nuclear exnor circadian variation in mRNA-S14 levels are ob- tracts binds to this segment of servedin the othertissuesexpressing the514 gene,P1 the S14 gene
Previous studies had demonstrated that a single hypersensitive site, HS-1, existed close to the transcription start site of the S14 gene in each of the tissues in which this gene is actively expressedand hormonally regulated.Hypersensitive sites are assumedto result from the associationof non-histone proteins with specific segments of DNA and to reflect alterations in chromatin structure necessary forgene expression

Summary

Introduction

Recent studies have described a DNase I hypersen- tissues of the rat, including lactating mammary gland and sitive site in the 6”flanking region of the rat hepatic white and brown adipose tissue. This protein, designated P1, was notpresentin extracts of other tissues, even those in which the geneis expressed and hormonally regulated. Since neither P1 binding activity HS-1 revealed that a protein present in hepatic nuclear exnor circadian variation in mRNA-S14 levels are ob- tracts (designated P1) binds to this segment of servedin the othertissuesexpressing the514 gene,P1 the S14 gene.

Results

Conclusion