Study of the hypoxia-dependent regulation of human CYGB gene

• Published in: Biochemical and biophysical research communications 2007-12, Vol.364 (1), p.145-150
• Main Authors: Guo, Xiumei, Philipsen, Sjaak, Tan-Un, Kian-Cheng
• Format: Article
• Language: English
• Subjects: Cell Line; Chromatin Immunoprecipitation; Cytoglobin (CYGB); Electrophoretic Mobility Shift Assay; Gene Expression Regulation; Globins - genetics; HeLa Cells; Humans; Hypoxia; Hypoxia - physiopathology; Hypoxia inducible factor (HIF-1); Hypoxia responsive elements (HREs); Hypoxia-Inducible Factor 1 - metabolism; Mutagenesis, Site-Directed; Normoxia; Promoter Regions, Genetic; Up-Regulation
• ISSN: 0006-291X; 1090-2104
• DOI: 10.1016/j.bbrc.2007.09.108

Cytoglobin (CYGB) is ubiquitously expressed in all tissues and has been characterized as a respiratory protein in connective tissues. CYGB is up-regulated during hypoxia, implicating its function in maintaining the homeostasis redox of the cell. Here, we study the underlying molecular mechanisms by which hypoxia regulates human CYGB gene expression. When cells were subjected to hypoxia, the expression of endogenous CYGB was up-regulated ∼1.7-fold in BEAS-2B cells ( p ⩽ 0.05) and ∼1.6-fold in HeLa cells ( p ⩽ 0.05). Dual-luciferase assays and site directed mutagenesis showed the presence of hypoxia responsive elements (HREs) at positions −141, −144 and −448 that were essential for activation of CYGB expression under hypoxic conditions. The binding of hypoxia inducible factor (HIF-1) protein to the HREs was confirmed by gel shift and chromatin immunoprecipitation (ChIP) assays. These results indicate that HRE motifs are directly involved in the activation of the CYGB transcription under hypoxia.