Quiescent and proliferative fibroblasts exhibit differential p300 HAT activation through control of 5-methoxytryptophan production

• Published in: PloS one 2014-02, Vol.9 (2), p.e88507-e88507
• Main Authors: Cheng, Huei-Hsuan, Wang, Kai-Hsuan, Chu, Ling-yun, Chang, Tzu-Ching, Kuo, Cheng-Chin, Wu, Kenneth K
• Format: Article
• Language: English
• Subjects: Acetic acid; Activation; Anti-Inflammatory Agents - chemistry; Biology; Cell cycle; Cell Differentiation; Cell Proliferation; Chromatin; Chromatography; Chromatography, High Pressure Liquid; Clinical medicine; COX-2 inhibitors; Cyclooxygenase 2 - metabolism; Cyclooxygenase-2; Cytokines; Deoxyribonucleic acid; DNA; Drug development; Enzymes; Event-related potentials; Exhibitions; Fibroblasts; Fibroblasts - cytology; Gene expression; Gene Silencing; Histone acetyltransferase; Histones; Humans; Immunoassay; Immunoenzyme Techniques; Inflammation; Liquid chromatography; Mass Spectrometry; Medical research; Medicine; Metabolism; Metabolites; Methyltransferase; p300-CBP Transcription Factors - metabolism; Phorbol 12-myristate 13-acetate; Promoter Regions, Genetic; Proteins; Quadrupoles; RNA, Small Interfering - metabolism; Rodents; Sepharose - chemistry; siRNA; Streptavidin - chemistry; Transcription; Transcription (Genetics); Tryptophan; Tryptophan - analogs & derivatives; Tryptophan - chemistry; Tryptophan hydroxylase; Tumor necrosis factor-TNF
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0088507

Quiescent fibroblasts possess unique genetic program and exhibit high metabolic activity distinct from proliferative fibroblasts. In response to inflammatory stimulation, quiescent fibroblasts are more active in expressing cyclooxygenase-2 and other proinflammatory genes than proliferative fibroblasts. The underlying transcriptional mechanism is unclear. Here we show that phorbol 12-myristate 13-acetate (PMA) and cytokines increased p300 histone acetyltransferase activity to a higher magnitude (> 2 fold) in quiescent fibroblasts than in proliferative fibroblasts. Binding of p300 to cyclooxygenase-2 promoter was reduced in proliferative fibroblasts. By ultrahigh-performance liquid chromatography coupled with a quadrupole time of flight mass spectrometer and enzyme-immunoassay, we found that production of 5-methoxytryptophan was 2-3 folds higher in proliferative fibroblasts than that in quiescent fibroblasts. Addition of 5-methoxytryptophan and its metabolic precursor, 5-hydroxytryptophan, to quiescent fibroblasts suppressed PMA-induced p300 histone acetyltransferase activity and cyclooxygenase-2 expression to the level of proliferative fibroblasts. Silencing of tryptophan hydroxylase-1 or hydroxyindole O-methyltransferase in proliferative fibroblasts with siRNA resulted in elevation of PMA-induced p300 histone acetyltransferase activity to the level of that in quiescent fibroblasts, which was rescued by addition of 5-hydroxytryptophan or 5-methoxytryptophan. Our findings indicate that robust inflammatory gene expression in quiescent fibroblasts vs. proliferative fibroblasts is attributed to uncontrolled p300 histone acetyltransferase activation due to deficiency of 5-methoxytryptophan production. 5-methoxytryptophan thus is a potential valuable lead compound for new anti-inflammatory drug development.