title: NKCC1 mediates traumatic brain injury-induced hippocampal neurogenesis through CREB phosphorylation and HIF-1α expression.
abstract: Traumatic brain injury (TBI) is one of the most prevalent causes of worldwide mortality and morbidity. We previously had evidenced that TBI induced Na-K-2Cl co-transporter (NKCC1) upregulation in hippocampus. Here, we aim to investigate the role of NKCC1 in TBI-induced neurogenesis and the detailed mechanisms. The TBI-associated alternations in the expression of NKCC1, HIF-1α, VEGF, MAPK cascade, and CREB phosphorylation were analyzed by Western blot. TBI-induced neurogenesis was determined by immuno-fluorescence labeling. Chromatin immunoprecipitation was used to elucidate whether HIF-1α would activate VEGF gene after TBI. We found that the level of hippocampal NKCC1 and VEGF began to rise 8 h after TBI, and both of them reached maxima at day 7. Along with the upregulation of NKCC1 and VEGF, MAPK cascade was activated and hippocampal neurogenesis was promoted. Administration of CREB antisense oligonucleotide significantly attenuated the expression of HIF-1α, while HIF-1α antisense oligonucleotide exhibited little effect on the expression of CREB. However, HIF-1α antisense oligonucleotide administration did effectively suppress the expression of VEGF. Our results of the chromosome immunoprecipitation also indicated that HIF-1α could directly act on the VEGF promoter and presumably would elevate the VEGF expression after TBI. All these results have illustrated the correlation between NKCC1 upregulation and TBI-associated neurogenesis. The pathway involves the activation of Raf/MEK/ERK cascade, CREB phosphorylation, and HIF-1α upregulation, and finally leads to the stimulation of VEGF expression and the induction of neurogenesis.
authors.affiliation: Department of Life Science, National Taiwan Normal University, Taipei, Taiwan.
authors.forename: Kwok-Tung
authors.initials: KT
authors.lastname: Lu
authors.forename: Tai-Chun
authors.initials: TC
authors.lastname: Huang
authors.forename: Jia-Yi
authors.initials: JY
authors.lastname: Wang
authors.forename: Ya-Shen
authors.initials: YS
authors.lastname: You
authors.forename: Jian-Liang
authors.initials: JL
authors.lastname: Chou
authors.forename: Michael W Y
authors.initials: MW
authors.lastname: Chan
authors.forename: Peter Y Y
authors.initials: PY
authors.lastname: Wo
authors.forename: Tamara G
authors.initials: TG
authors.lastname: Amstislavskaya
authors.forename: Maria A
authors.initials: MA
authors.lastname: Tikhonova
authors.forename: Yi-Ling
authors.initials: YL
authors.lastname: Yang
mesh_terms: D000818:Animals; D001665:Binding Sites; D001930:Brain Injuries / Q000235:genetics / Q000378:metabolism* / Q000473:pathology / Q000503:physiopathology; D017362:Cyclic AMP Response Element-Binding Protein / Q000235:genetics / Q000378:metabolism*; D004195:Disease Models, Animal; D005786:Gene Expression Regulation; D006624:Hippocampus / Q000378:metabolism* / Q000473:pathology / Q000503:physiopathology; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000235:genetics / Q000378:metabolism*; D020935:MAP Kinase Signaling System; D008297:Male; D055495:Neurogenesis; D009474:Neurons / Q000378:metabolism* / Q000473:pathology; D016376:Oligonucleotides, Antisense / Q000235:genetics / Q000378:metabolism; D010766:Phosphorylation; D011401:Promoter Regions, Genetic; D017208:Rats, Wistar; D064506:Solute Carrier Family 12, Member 2 / Q000378:metabolism*; D013997:Time Factors; D014158:Transcription, Genetic; D042461:Vascular Endothelial Growth Factor A / Q000378:metabolism
chemical_list: C508137:Creb1 protein, rat; D017362:Cyclic AMP Response Element-Binding Protein; C497444:Hif1a protein, rat; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D016376:Oligonucleotides, Antisense; C578879:Slc12a2 protein, rat; D064506:Solute Carrier Family 12, Member 2; D042461:Vascular Endothelial Growth Factor A; C467498:vascular endothelial growth factor A, rat