title: Hypoxic adaptation engages the CBP/CREST-induced coactivator complex of Creb-HIF-1α in transactivating murine neuroblastic glucose transporter.
abstract: We have shown in vitro a hypoxia-induced time-dependent increase in facilitative glucose transporter isoform 3 (GLUT3) expression in N2A murine neuroblasts. This increase in GLUT3 expression is partially reliant on a transcriptional increase noted in actinomycin D and cycloheximide pretreatment experiments. Transient transfection assays in N2A neuroblasts using murine glut3-luciferase reporter constructs mapped the hypoxia-induced enhancer activities to -857- to -573-bp and -203- to -177-bp regions. Hypoxia-exposed N2A nuclear extracts demonstrated an increase in HIF-1α and p-Creb binding to HRE (-828 to -824 bp) and AP-1 (-187 to -180 bp) cis-elements, respectively, in electromobility shift and supershift assays, which was confirmed by chromatin immunoprecipitation assays. In addition, the interaction of CBP with Creb and HIF-1α and CREST with CBP in hypoxia was detected by coimmunoprecipitation. Furthermore, small interference (si)RNA targeting Creb in these cells decreased endogenous Creb concentrations that reduced by twofold hypoxia-induced glut3 gene transcription. Thus, in N2A neuroblasts, phosphorylated HIF-1α and Creb mediated the hypoxia-induced increase in glut3 transcription. Coactivation by the Ca⁺⁺-dependent CREST and CBP proteins may enhance cross-talk between p-Creb-AP-1 and HIF-1α/HRE of the glut3 gene. Collectively, these processes can facilitate an adaptive response to hypoxic energy depletion targeted at enhancing glucose transport and minimizing injury while fueling the proliferative potential of neuroblasts.
authors: Department of Pediatrics, Division of Neonatology and Developmental Biology, Neonatal Research Center, David Geffen School of Medicine at University of California Los Angeles, Los Angeles, CA 90095, USA.
authors: Shanthie
authors: S
authors: Thamotharan
authors: Nupur
authors: N
authors: Raychaudhuri
authors: Masatoshi
authors: M
authors: Tomi
authors: Bo-Chul
authors: BC
authors: Shin
authors: Sherin U
authors: SU
authors: Devaskar
mesh_terms: D000818:Animals; D050882:CREB-Binding Protein / Q000378:metabolism*; D015687:Cell Hypoxia; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism; D002478:Cells, Cultured; D017362:Cyclic AMP Response Element-Binding Protein / Q000235:genetics / Q000378:metabolism*; D017930:Genes, Reporter; D051274:Glucose Transporter Type 3 / Q000096:biosynthesis* / Q000235:genetics / Q000378:metabolism; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000378:metabolism*; D051379:Mice; D008807:Mice, Inbred BALB C; D009419:Nerve Tissue Proteins / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism; D058953:Neural Stem Cells / Q000166:cytology / Q000378:metabolism*; D009474:Neurons / Q000166:cytology / Q000378:metabolism; D021381:Protein Transport; D034622:RNA Interference; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis / Q000378:metabolism; D015398:Signal Transduction; D015534:Trans-Activators / Q000378:metabolism*; D015533:Transcriptional Activation; D015854:Up-Regulation
chemical_list: C580962:CREST protein, mouse; C492004:Creb1 protein, mouse; D017362:Cyclic AMP Response Element-Binding Protein; D051274:Glucose Transporter Type 3; C497443:Hif1a protein, mouse; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D009419:Nerve Tissue Proteins; D011993:Recombinant Fusion Proteins; C495689:Slc2a3 protein, mouse; D015534:Trans-Activators; D050882:CREB-Binding Protein; C494364:Crebbp protein, mouse