Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.4.21.64 (proteinase K)
 4,071 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The structure of DNAase I hypersensitive site 1 (Hss-1), located adjacent to the 5' end of the rat liver S14 gene, is regulated by tissue-specific factors, and its formation correlates with the transcriptional activation of the S14 gene. We propose that tissue-specific trans-acting factors interacting with key cis-linked elements within this site function in the initiation of S14 gene transcription. To examine this hypothesis we used DNAase I footprint, gel shift and in vitro transcriptional analyses to identify cis-linked elements that function in the control of S14 gene transcription. Binding of rat liver nuclear proteins to the S14 promoter (from -8 to -464 bp) produced four DNAase I footprints (designated A-D). Gel shift studies showed that DNA-protein binding was tissue- and sequence-specific, differentially heat-sensitive, and abolished by proteinase K. The function of the four cis-acting elements was assessed by using an in vitro transcription initiation assay in which the S14 promoter was fused to a reporter gene (G-free cassette). Deletion studies showed that nuclear factors binding to regions A (-48 to -63 bp), B (-88 to -113 bp) and D (-286 to -310 bp) enhanced the rate of initiation of transcription, while proteins binding to region C (-227 to -244 bp) suppressed the rate of initiation of transcription. Based on oligonucleotide competition studies, we suggest that hepatic NF-1 (or a related protein) binding to the A region enhances the rate of initiation of S14 gene transcription. Since trans-acting factors interacting with regions B and D are found in liver but not in spleen or kidney, we suggest that the proteins interacting with these regions may be involved in the tissue-specific augmentation of S14 gene transcription.
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PMID:Identification of functional cis-acting elements within the rat liver S14 promoter. 176 39

The rat hepatic S14 gene is regulated by L-triiodothyronine (T3) and codes for a cytosolic protein (pI 4.9 and Mr 17,010) that is believed to be involved in lipogenesis. Recent studies have identified at least five DNase I hypersensitive sites (HS 1-5) in hepatic chromatin flanking the 5' region of the gene. The HS-1 site is situated immediately adjacent to the transcription initiation site. We have isolated a DNA fragment (USS-1) which contains a portion of the HS-1 site to examine the binding of nuclear proteins to S14 DNA. DNase I footprinting studies demonstrated that material extracted from hepatic nuclei with 0.42 M NaCl contained proteinase K-sensitive factors (presumed to be proteins), which bind to USS-1 DNA between positions -63 and -48 (PS-1) relative to the transcription initiation site. Examination of the binding activity with a synthetic oligonucleotide identical to the protected sequence indicated the formation of at least three protein-DNA complexes. The DNA binding activity of the PS-1 binding protein or proteins correlated with the T3 regulated expression of mRNA-S14. Although the nucleotide sequence of PS-1 closely resembles the binding site for the CCAAT transcription factor (CTF/NF-1), competition studies attempting to displace protein binding from the PS-1 sequence with DNA fragments containing the CTF/NF-1 binding motif were unsuccessful. In vitro transcriptional assay studies suggested that the DNA fragment (-441 to -2) containing the PS-1 site promotes the transcription of the S14 gene in an orientation fashion. The in vitro transcriptional activity of the S14 DNA containing the PS-1 sequence was significantly higher in hepatonuclear extracts from hyperthyroid compared with euthyroid or hypothyroid animals. In summary, our findings indicate that the DNA binding activity of proteins which bind to PS-1 site is influenced by the thyroid status of the animal.
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PMID:Binding of nuclear proteins to the rat liver S14 gene is influenced by thyroid state. 234 5