title: Transcriptional regulation mechanisms of hypoxia-induced neuroglobin gene expression.
abstract: Ngb (neuroglobin) has been identified as a novel endogenous neuroprotectant. However, little is known about the regulatory mechanisms of Ngb expression, especially under conditions of hypoxia. In the present study, we located the core proximal promoter of the mouse Ngb gene to a 554 bp segment, which harbours putative conserved NF-κB (nuclear factor κB)- and Egr1 (early growth-response factor 1) -binding sites. Overexpression and knockdown of transcription factors p65, p50, Egr1 or Sp1 (specificity protein 1) increased and decreased Ngb expression respectively. Experimental assessments with transfections of mutational Ngb gene promoter constructs, as well as EMSA (electrophoretic mobility-shift assay) and ChIP (chromatin immunoprecipitation) assays, demonstrated that NF-κB family members (p65, p50 and cRel), Egr1 and Sp1 bound in vitro and in vivo to the proximal promoter region of the Ngb gene. Moreover, a κB3 site was found as a pivotal cis-element responsible for hypoxia-induced Ngb promoter activity. NF-κB (p65) and Sp1 were also responsible for hypoxia-induced up-regulation of Ngb expression. Although there are no conserved HREs (hypoxia-response elements) in the promoter of the mouse Ngb gene, the results of the present study suggest that HIF-1α (hypoxia-inducible factor-1α) is also involved in hypoxia-induced Ngb up-regulation. In conclusion, we have identified that NF-κB, Egr1 and Sp1 played important roles in the regulation of basal Ngb expression via specific interactions with the mouse Ngb promoter. NF-κB, Sp1 and HIF-1α contributed to the up-regulation of mouse Ngb gene expression under hypoxic conditions.
authors.affiliation: Key Laboratory of Protein Chemistry and Developmental Biology of Education Ministry of China, College of Life Science, Hunan Normal University, Changsha 410081, China.
authors.forename: Ning
authors.initials: N
authors.lastname: Liu
authors.forename: Zhanyang
authors.initials: Z
authors.lastname: Yu
authors.forename: Shuanglin
authors.initials: S
authors.lastname: Xiang
authors.forename: Song
authors.initials: S
authors.lastname: Zhao
authors.forename: Anna
authors.initials: A
authors.lastname: Tjärnlund-Wolf
authors.forename: Changhong
authors.initials: C
authors.lastname: Xing
authors.forename: Jian
authors.initials: J
authors.lastname: Zhang
authors.forename: Xiaoying
authors.initials: X
authors.lastname: Wang
mesh_terms: D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D015687:Cell Hypoxia; D045744:Cell Line, Tumor; D017124:Conserved Sequence; D051766:Early Growth Response Protein 1 / Q000235:genetics / Q000378:metabolism; D015870:Gene Expression; D005786:Gene Expression Regulation; D055785:Gene Knockdown Techniques; D017930:Genes, Reporter; D005914:Globins / Q000235:genetics* / Q000378:metabolism; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000235:genetics / Q000378:metabolism; D049410:Luciferases, Renilla / Q000096:biosynthesis / Q000235:genetics; D051379:Mice; D008810:Mice, Inbred C57BL; D008969:Molecular Sequence Data; D016328:NF-kappa B / Q000235:genetics / Q000378:metabolism; D009419:Nerve Tissue Proteins / Q000235:genetics* / Q000378:metabolism; D000078787:Neuroglobin; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D034622:RNA Interference; D016329:Sp1 Transcription Factor / Q000235:genetics / Q000378:metabolism; D014158:Transcription, Genetic
chemical_list: D051766:Early Growth Response Protein 1; C486109:Egr1 protein, mouse; C497443:Hif1a protein, mouse; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D016328:NF-kappa B; D009419:Nerve Tissue Proteins; D000078787:Neuroglobin; D016329:Sp1 Transcription Factor; D005914:Globins; D049410:Luciferases, Renilla