The NAMPT promoter is regulated by mechanical stress, signal transducer and activator of transcription 5, and acute respiratory distress syndrome-associated genetic variants.

TitleThe NAMPT promoter is regulated by mechanical stress, signal transducer and activator of transcription 5, and acute respiratory distress syndrome-associated genetic variants.
Publication TypeJournal Article
Year of Publication2014
AuthorsSun X, Elangovan VRamamoorth, Mapes B, Camp SM, Sammani S, Saadat L, Ceco E, Ma S-F, Flores C, MacDougall MS, Quijada H, Liu B, Kempf CL, Wang T, Chiang ET, Garcia JGN
JournalAm J Respir Cell Mol Biol
Volume51
Issue5
Pagination660-7
Date Published2014 Nov
ISSN Number1535-4989
Keywords5' Untranslated Regions, Acute Lung Injury, Animals, Cells, Cultured, Cytokines, Disease Models, Animal, DNA Methylation, Endothelial Cells, Epigenesis, Genetic, Gene Expression Regulation, Genetic Variation, Humans, Male, Mice, Inbred C57BL, Nicotinamide Phosphoribosyltransferase, Promoter Regions, Genetic, Pulmonary Artery, Respiration, Artificial, Respiratory Distress Syndrome, Adult, RNA, Small Interfering, STAT5 Transcription Factor, Stress, Mechanical, Tumor Suppressor Proteins
Abstract

<p>Increased nicotinamide phosphoribosyltransferase (NAMPT) transcription is mechanistically linked to ventilator-induced inflammatory lung injury (VILI), with VILI severity attenuated by reduced NAMPT bioavailability. The molecular mechanisms of NAMPT promoter regulation in response to excessive mechanical stress remain poorly understood. The objective of this study was to define the contribution of specific transcription factors, acute respiratory distress syndrome (ARDS)-associated single nucleotide polymorphisms (SNPs), and promoter demethylation to NAMPT transcriptional regulation in response to mechanical stress. In vivo NAMPT protein expression levels were examined in mice exposed to high tidal volume mechanical ventilation. In vitro NAMPT expression levels were examined in human pulmonary artery endothelial cells exposed to 5 or 18% cyclic stretch (CS), with NAMPT promoter activity assessed using NAMPT promoter luciferase reporter constructs with a series of nested deletions. In vitro NAMPT transcriptional regulation was further characterized by measuring luciferase activity, DNA demethylation, and chromatin immunoprecipitation. VILI-challenged mice exhibited significantly increased NAMPT expression in bronchoalveolar lavage leukocytes and in lung endothelium. A mechanical stress-inducible region (MSIR) was identified in the NAMPT promoter from -2,428 to -2,128 bp. This MSIR regulates NAMPT promoter activity, mRNA expression, and signal transducer and activator of transcription 5 (STAT5) binding, which is significantly increased by 18% CS. In addition, NAMPT promoter activity was increased by pharmacologic promoter demethylation and inhibited by STAT5 silencing. ARDS-associated NAMPT promoter SNPs rs59744560 (-948G/T) and rs7789066 (-2,422A/G) each significantly elevated NAMPT promoter activity in response to 18% CS in a STAT5-dependent manner. Our results show that NAMPT is a key novel ARDS therapeutic target and candidate gene with genetic/epigenetic transcriptional regulation in response to excessive mechanical stress.</p>

DOI10.1165/rcmb.2014-0117OC
Alternate JournalAm. J. Respir. Cell Mol. Biol.
PubMed ID24821571
PubMed Central IDPMC4224084
Grant ListP50 HL073994 / HL / NHLBI NIH HHS / United States
T32 GM079086 / GM / NIGMS NIH HHS / United States
R01-HL73994 / HL / NHLBI NIH HHS / United States