Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
10770948 | Biochemical and Biophysical Research Communications | 2005 | 6 Pages |
Abstract
While other plasma lipoproteins are exclusively expressed in liver and intestine, apoliprotein E (apoE) is ubiquitously synthesized in many tissues. To understand the molecular mechanism of non-tissue-specific apoE expression, we tested the testicular orphan receptor 4 (TR4) effect on apoE expression in different cell lines, such as HepG2, COS-1, and H1299 cells. Gel shift assay and 5â² promoter activity analyses identified one distinct hormone response element (TR4RE-DR0-apoE at â303 to â292 bp) that binds to TR4 and results in full induction of apoE gene transcription. TR4 also forms a complex with Sp1 to synergistically induce apoE expression via a region containing the TR4RE-DR0-apoE and the Sp1 binding site (â169 to â140Â bp). Induction of apoE expression by TR4 was also confirmed at the mRNA and protein levels in H1299 cells. Together, our data demonstrate that TR4 can enhance apoE gene expression via binding to TR4RE-DR0 in apoE 5â² promoter and this TR4 binding is essential for synergistic interaction with another transcription factor, Sp1.
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Authors
Eungseok Kim, Zhiming Yang, Ning-Chun Liu, Chawnshang Chang,