Abstract
The three members of the NR4A orphan nuclear receptor subfamily Nur77, Nurr1, and NOR-1, regulate a variety of biological functions including vascular disease and metabolism. In this study, we identified Four and a half LIM domains protein-2 (FHL2) as a novel interacting protein of NR4A nuclear receptors by yeast two-hybrid screen and co-immunoprecipitation studies. Each of the four LIM domains of FHL2 can bind Nur77, and both the amino-terminal domain and the DNA binding domain of Nur77 are involved in the interaction between FHL2 and Nur77. FHL2 represses Nur77 transcriptional activity in a dose-dependent manner, and short hairpin RNA-mediated knockdown of FHL2 results in increased Nur77 transcriptional activity. ChIP experiments on the enolase3 promoter revealed that FHL2 inhibits the association of Nur77 with DNA. FHL2 is highly expressed in human endothelial and smooth muscle cells, but not in monocytes or macrophages. To substantiate functional involvement of FHL2 in smooth muscle cell physiology, we demonstrated that FHL2 overexpression increases the growth of these cells, whereas FHL2 knockdown results in reduced DNA synthesis. Collectively, these studies suggest that association of FHL2 with Nur77 plays a pivotal role in vascular disease.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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DNA / biosynthesis
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DNA / genetics
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Endothelial Cells / cytology
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Endothelial Cells / metabolism
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Gene Expression Regulation / physiology*
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Gene Knockdown Techniques
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HEK293 Cells
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Humans
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LIM-Homeodomain Proteins / genetics
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LIM-Homeodomain Proteins / metabolism*
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Macrophages / cytology
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Macrophages / metabolism
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Monocytes / cytology
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Monocytes / metabolism
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Muscle Proteins / genetics
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Muscle Proteins / metabolism*
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Myocytes, Smooth Muscle / cytology
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Myocytes, Smooth Muscle / metabolism
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Nuclear Receptor Subfamily 4, Group A, Member 1 / genetics
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Nuclear Receptor Subfamily 4, Group A, Member 1 / metabolism*
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Organ Specificity / physiology
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Phosphopyruvate Hydratase / genetics
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Phosphopyruvate Hydratase / metabolism
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Promoter Regions, Genetic / physiology
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Protein Structure, Tertiary
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Repressor Proteins / genetics
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Repressor Proteins / metabolism*
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Transcription Factors / genetics
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Transcription Factors / metabolism*
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Transcription, Genetic / physiology*
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Two-Hybrid System Techniques
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Vascular Diseases / genetics
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Vascular Diseases / metabolism
Substances
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FHL2 protein, human
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LIM-Homeodomain Proteins
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Muscle Proteins
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NR4A1 protein, human
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Nuclear Receptor Subfamily 4, Group A, Member 1
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Repressor Proteins
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Transcription Factors
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DNA
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Phosphopyruvate Hydratase