title: Clozapine induces chloride channel-4 expression through PKA activation and modulates CDK5 expression in SH-SY5Y and U87 cells.
abstract: OBJECTIVE
  Second-generation antipsychotic drugs, such as clozapine, were reported to enhance neurite outgrowth by nerve growth factor in PC12 cells. The authors previously showed that chloride channel 4 (CLC-4) is responsible for nerve growth factor-induced neurite outgrowth in neuronal cells. In this study, we examined whether clozapine induces CLC-4 in neuroblastoma and glioma cells.
  
  
  METHODS
  The effect of clozapine on CLC-4 expression was examined in neuroblastoma (SH-SY5Y) and glioma (U87) cells. To investigate the signaling pathway responsible for clozapine-induced CLC-4 expression, the phosphorylation of cAMP response element-binding protein (CREB), which binds CRE in the promoter of the human CLC-4 gene, was examined. To identify the target of clozapine induced CLC-4, CLC-4 siRNA was introduced to neuroblastoma and glioma cells for functional knockdown.
  
  
  RESULTS
  We observed that clozapine increased CLC-4 expression in both SH-SY5Y and U87 cells. Clozapine induced CREB phosphorylation, but in the presence of inhibitor of protein kinase A (an upstream kinase of CREB) clozapine-induced CLC-4 expression was suppressed. Finally, we found that CLC-4 knockdown suppressed clozapine-induced cyclin-dependent kinase 5 (CDK5) expression in SH-SY5Y and U-87 cells suggesting CDK5 as potential molecular target of clozapine induced CLC-4 expression.
  
  
  CONCLUSIONS
  The results of the present study suggest that clozapine's therapeutic effect may include the induction of CLC-4 which is dependent on CREB activation via PKA. We also found that functional knockdown of CLC-4 resulted in reduction of CDK5 expression, which may also be implicated in clozapine's therapeutic effect.
authors.affiliation: Dongguk University Research Institute of Biotechnology, 27-3, Phildong 3, Joong-gu, Seoul, 100-715.
authors.forename: Songhee
authors.initials: S
authors.lastname: Jeon
authors.affiliation: Department of Child Psychiatry, National Center for Child and Adolescent Psychiatry, Seoul National Hospital, Seoul, 143-711.
authors.forename: Yeni
authors.initials: Y
authors.lastname: Kim
authors.affiliation: Department of Neuropsychiatry, Dongguk University Medical School, Dongguk University International Hospital, Goyang-si, Gyeonggi-do, 410-773; Institute of Clinical Psychopharmacology, Dongguk University International Hospital, Goyang-si, Gyeonggi-do, 410-773.
authors.forename: In-Won
authors.initials: IW
authors.lastname: Chung
authors.affiliation: Department of Neuropsychiatry, Dongguk University Medical School, Dongguk University International Hospital, Goyang-si, Gyeonggi-do, 410-773; Institute of Clinical Psychopharmacology, Dongguk University International Hospital, Goyang-si, Gyeonggi-do, 410-773. Electronic address: kys@snu.ac.kr.
authors.forename: Yong Sik
authors.initials: YS
authors.lastname: Kim
mesh_terms: D000704:Analysis of Variance; D014150:Antipsychotic Agents / Q000494:pharmacology*; D050882:CREB-Binding Protein / Q000378:metabolism; D045744:Cell Line, Tumor; D003024:Clozapine / Q000494:pharmacology*; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism*; D051360:Cyclin-Dependent Kinase 5 / Q000235:genetics / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D004789:Enzyme Activation / Q000187:drug effects; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects*; D005909:Glioblastoma / Q000473:pathology; D006801:Humans; D020932:Nerve Growth Factor / Q000494:pharmacology; D009447:Neuroblastoma / Q000473:pathology; D034741:RNA, Small Interfering / Q000494:pharmacology
chemical_list: D014150:Antipsychotic Agents; D034741:RNA, Small Interfering; D020932:Nerve Growth Factor; D050882:CREB-Binding Protein; D051360:Cyclin-Dependent Kinase 5; D017868:Cyclic AMP-Dependent Protein Kinases; C495905:CDK5 protein, human; D003024:Clozapine
keywords: Chloride channel-4; Clozapine; Cyclin-dependent kinase 5; SH-SY5Y; U87