Mechanism Governing Human Kappa-Opioid Receptor Expression under Desferrioxamine-Induced Hypoxic Mimic Condition in Neuronal NMB Cells

• Published in: International journal of molecular sciences 2017-01, Vol.18 (1), p.211-211
• Main Authors: Babcock, Jennifer, Herrera, Alberto, Coricor, George, Karch, Christopher, Liu, Alexander H, Rivera-Gines, Aida, Ko, Jane L
• Format: Article
• Language: English
• Subjects: Adaptation; Basic Helix-Loop-Helix Transcription Factors - genetics; Basic Helix-Loop-Helix Transcription Factors - metabolism; Blotting, Western; Cell Adhesion - genetics; Cell Hypoxia; Cell Line, Tumor; Cell Survival - genetics; Deferoxamine; Deferoxamine - pharmacology; desferrioxamine; Gene Expression Regulation, Neoplastic - drug effects; HIF response elements; human kappa-opioid receptor; human NMB neuronal cells; Humans; Hypoxia; hypoxia inducible factor-1α; Hypoxia-inducible factor 1; Hypoxia-Inducible Factor 1, alpha Subunit - genetics; Hypoxia-Inducible Factor 1, alpha Subunit - metabolism; Hypoxia-inducible factor 1a; Mutagenesis; Mutation; Narcotics; Neuroblastoma - genetics; Neuroblastoma - metabolism; Neuroblastoma - pathology; Neurons; Opioid receptors (type kappa); Polymerase chain reaction; Receptors, Opioid, kappa - genetics; Receptors, Opioid, kappa - metabolism; Regulatory sequences; Response Elements - genetics; Reverse Transcriptase Polymerase Chain Reaction; RNA Interference; Siderophores - pharmacology; siRNA
• ISSN: 1422-0067; 1661-6596; 1422-0067
• DOI: 10.3390/ijms18010211

Cellular adaptation to hypoxia is a protective mechanism for neurons and relevant to cancer. Treatment with desferrioxamine (DFO) to induce hypoxia reduced the viability of human neuronal NMB cells. Surviving/attached cells exhibited profound increases of expression of the human kappa-opioid receptor (hKOR) and hypoxia inducible factor-1α (HIF-1α). The functional relationship between hKOR and HIF-1α was investigated using RT-PCR, Western blot, luciferase reporter, mutagenesis, siRNA and receptor-ligand binding assays. In surviving neurons, DFO increased HIF-1α expression and its amount in the nucleus. DFO also dramatically increased hKOR expression. Two (designated as HIFC and D) out of four potential HIF response elements of the gene (HIFA-D) synergistically mediated the DFO response. Mutation of both elements completely abolished the DFO-induced effect. The CD11 plasmid (containing HIFC and D with an 11 bp spacing) produced greater augmentation than that of the CD17 plasmid (HIFC and D with a 17 bp-spacing), suggesting that a proper topological interaction of these elements synergistically enhanced the promoter activity. HIF-1α siRNA knocked down the increase of endogenous HIF-1α messages and diminished the DFO-induced increase of hKOR expression. Increased hKOR expression resulted in the up-regulation of hKOR protein. In conclusion, the adaptation of neuronal hKOR under hypoxia was governed by HIF-1, revealing a new mechanism of hKOR regulation.