title: LOX-1 transcription.
abstract: The importance of the lectin-like oxidized LDL receptor (LOX-1) gene in cardiovascular and other diseases is slowly being revealed. LOX-1 gene expression appears to be a "canary in a coal mine" for atherogenesis, being strongly up-regulated early on in a number of cell types when they are activated, and predicting the sites of future disease. From this early time point the LOX-1 protein often participates in the disease process itself. While gene/protein expression can be regulated on a multiplicity of levels, the most basic and important mode of regulation is usually transcriptional. There are very few studies on the transcriptional regulation of the human LOX-1 promoter; fewer still on definitive mapping of the transcription factors involved. It is known that a wide variety of stimuli up-regulate LOX-1, usually/probably on the transcriptional level. Angiotensin II (Ang II) is one important regulator of renin-angiotensin system and stimulator LOX-1. Ang II is known to up-regulate LOX-1 transcription through an NF-kB motif located at nt -2158. Oxidized low density lipoprotein (ox-LDL) is another important cardiovascular regulator, particularly of atherosclerotic disease, and a strong stimulator of LOX-1. Ox-LDL is known to up-regulate LOX-1 transcription through an Oct-1 motif located at nt -1556. The subsequent enhanced LOX-1 receptor numbers and their binding by ox-LDL ligand triggers a positive feedback loop, increasing further LOX-1 expression, with a presently unknown regulatory governor. The Oct-1 gene also has its own Oct-1-driven positive feedback loop, which likely also contributes to LOX-1 up-regulation. There is also data which suggests the involvement of the transcription factor AP-1 during stimulation with Phorbol 12-myristate acetate. While the importance of NF-κB as a transcriptional regulator of cardiovascular-relevant genes is well known, the importance of Oct-1 is not. Data suggests that Oct-1-mediated up-regulation of transcription is an early event in the stimulation of LOX-1 by ox-LDL. Yet Oct-1 also down-regulates cardiovascular-relevant genes by suppressing NF-κB transactivation. Thus, Oct-1 is presently somewhat of an enigma, up-regulating and down-regulating genes seemingly at random without an overall theme (with the exception of cell cycle). Yet the up-regulation of LOX-1 by ox-LDL is a very important event in atherogenesis (both early and late) and Oct-1 is, therefore, an important transcriptional gatekeeper of this important atherogenic trigger.
authors.affiliation: Central Arkansas Veterans Healthcare System, 111J, 4300 West 7th Street, Little Rock, AR 72205, USA. plhermonat@uams.edu
authors.forename: Paul L
authors.initials: PL
authors.lastname: Hermonat
authors.forename: Hongqing
authors.initials: H
authors.lastname: Zhu
authors.forename: Maohua
authors.initials: M
authors.lastname: Cao
authors.forename: Jawahar L
authors.initials: JL
authors.lastname: Mehta
mesh_terms: D000818:Animals; D050197:Atherosclerosis / Q000235:genetics* / Q000378:metabolism*; D005786:Gene Expression Regulation; D006801:Humans; D051127:Scavenger Receptors, Class E / Q000096:biosynthesis* / Q000235:genetics*; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism*; D014158:Transcription, Genetic
chemical_list: D051127:Scavenger Receptors, Class E; D014157:Transcription Factors