title: Cellular localization and functional significance of CYP3A4 in the human epileptic brain.
abstract: OBJECTIVE
  Compelling evidence supports the presence of P450 enzymes (CYPs) in the central nervous system (CNS). However, little information is available on the localization and function of CYPs in the drug-resistant epileptic brain. We have evaluated the pattern of expression of the specific enzyme CYP3A4 and studied its co-localization with MDR1. We also determined whether an association exists between CYP3A4 expression and cell survival.
  
  
  METHODS
  Brain specimens were obtained from eight patients undergoing resection to relieve drug-resistant seizures or to remove a cavernous angioma. Each specimen was partitioned for either immunostaining or primary culture of human endothelial cells and astrocytes. Immunostaining was performed using anti-CYP3A4, MDR1, GFAP, or NeuN antibodies. High performance liquid chromatography-ultraviolet (HPLC-UV) analysis was used to quantify carbamazepine (CBZ) metabolism by these cells. CYP3A4 expression was correlated to DAPI) condensation, a marker of cell viability. Human embryonic kidney (HEK) cells were transfected with 4',6-diamidino-2-phenylindole (CYP3A4 to further evaluate the link between CYP3A4 levels, CBZ metabolism, and cell viability.
  
  
  RESULTS
  CYP3A4 was expressed by blood-brain barrier (BBB) endothelial cells and by the majority of neurons (75 ± 10%). Fluorescent immunostaining showed coexpression of CYP3A4 and MDR1 in endothelial cells and neurons. CYP3A4 expression inversely correlated with DAPI nuclear condensation. CYP3A4 overexpression in HEK cells conferred resistance to cytotoxic levels of carbamazepine. CYP3A4 levels positively correlated with the amount of CBZ metabolized.
  
  
  CONCLUSIONS
  CYP3A4 brain expression is not only associated with drug metabolism but may also represent a cytoprotective mechanism. Coexpression of CYP3A4 and MDR1 may be involved in cell survival in the diseased brain.
authors.affiliation: Cerebrovascular ResearchDepartments of Cell Biology Molecular Medicine Neurological Surgery Epilepsy Center, Cleveland Clinic Foundation, Cleveland, Ohio 44195, USA.
authors.forename: Chaitali
authors.initials: C
authors.lastname: Ghosh
authors.forename: Nicola
authors.initials: N
authors.lastname: Marchi
authors.forename: Nirav K
authors.initials: NK
authors.lastname: Desai
authors.forename: Vikram
authors.initials: V
authors.lastname: Puvenna
authors.forename: Mohammed
authors.initials: M
authors.lastname: Hossain
authors.forename: Jorge
authors.initials: J
authors.lastname: Gonzalez-Martinez
authors.forename: Andreas V
authors.initials: AV
authors.lastname: Alexopoulos
authors.forename: Damir
authors.initials: D
authors.lastname: Janigro
mesh_terms: D018435:ATP Binding Cassette Transporter, Subfamily B; D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000378:metabolism*; D000293:Adolescent; D000328:Adult; D000927:Anticonvulsants / Q000493:pharmacokinetics / Q000627:therapeutic use; D017209:Apoptosis / Q000502:physiology; D001253:Astrocytes / Q000473:pathology*; D001812:Blood-Brain Barrier / Q000502:physiology*; D001921:Brain / Q000473:pathology*; D002220:Carbamazepine / Q000493:pharmacokinetics; D002648:Child; D002675:Child, Preschool; D051544:Cytochrome P-450 CYP3A / Q000235:genetics / Q000378:metabolism*; D004351:Drug Resistance; D042783:Endothelial Cells / Q000473:pathology*; D004833:Epilepsy, Temporal Lobe / Q000188:drug therapy / Q000473:pathology* / Q000601:surgery; D005260:Female; D057809:HEK293 Cells; D020786:Hemangioma, Cavernous, Central Nervous System / Q000473:pathology / Q000601:surgery; D006801:Humans; D007223:Infant; D008297:Male; D009474:Neurons / Q000473:pathology*; D014162:Transfection; D014402:Tuberous Sclerosis / Q000473:pathology / Q000601:surgery
chemical_list: C513055:ABCB1 protein, human; D018435:ATP Binding Cassette Transporter, Subfamily B; D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D000927:Anticonvulsants; D002220:Carbamazepine; D051544:Cytochrome P-450 CYP3A; C510163:CYP3A4 protein, human