title: An invertebrate model for CNS drug discovery: Transcriptomic and functional analysis of a mammalian P-glycoprotein ortholog.
abstract: BACKGROUND
  ABC efflux transporters at the blood brain barrier (BBB), namely the P-glycoprotein (P-gp), restrain the development of central nervous system (CNS) drugs. Consequently, early screening of CNS drug candidates is pivotal to identify those affected by efflux activity. Therefore, simple, high-throughput and predictive screening models are required. The grasshopper (locust) has been developed as an invertebrate in situ model for BBB permeability assessment, as it has shown similarities to vertebrate models.
  
  
  METHODS
  Transcriptome profiling of ABC efflux transporters in the locust brain was performed. Subsequently, identified transcripts were matched with their counterparts in human, rat, mouse and Drosophila melanogaster, based on amino acid sequence similarity, and phylogenetic trees were constructed to reveal the most likely evolutionary history of the proteins. Further, functional characterization of a P-gp ortholog was achieved through transport studies, using a selective P-gp substrate and locust brain in situ, followed by kinetic analyses.
  
  
  RESULTS
  A protein with high sequence similarity to the ABCB1 gene of vertebrates was found in the locust brain, which encodes P-gp in human and is considered the most vital efflux pump. Functionally, this model showed transport kinetic behaviors comparable to those obtained from in vitro models. Particularly, substrate affinity of the putative P-gp was observed as in P-gp expressing cells lines, used for predicting drug penetration across biological barriers.
  
  
  CONCLUSIONS
  Findings suggest a conserved mechanism of brain efflux activity between insects and vertebrates, confirming that this model holds promise for inexpensive and high-throughput screening relative to in vivo models, for CNS drug discovery.
authors.affiliation: Department of Pharmacy, University of Copenhagen, Universitetsparken 2, 2100 København Ø, Denmark; Faculty of Nursing, Pharmacy and Health professions, Birzeit University, PO Box 14, Birzeit, West Bank, Palestine. Telephone: +972-2-298-2000, Fax: +972-2-281-0656.. Electronic address: hannaq1996@gmail.com.
authors.forename: Sonia
authors.initials: S
authors.lastname: Al-Qadi
authors.affiliation: Centre for Social Evolution, Department of Biology, University of Copenhagen, Universitetsparken 15, 2100 København Ø, Denmark.
authors.forename: Morten
authors.initials: M
authors.lastname: Schiøtt
authors.affiliation: Department of Pharmacy, University of Copenhagen, Universitetsparken 2, 2100 København Ø, Denmark.
authors.forename: Steen Honoré
authors.initials: SH
authors.lastname: Hansen
authors.affiliation: Department of Pharmacy, University of Copenhagen, Universitetsparken 2, 2100 København Ø, Denmark.
authors.forename: Peter Aadal
authors.initials: PA
authors.lastname: Nielsen
authors.affiliation: Division of Discovery Chemistry, H. Lundbeck A/S, Copenhagen, Denmark; Division of Drug Metabolism and Pharmacokinetics, H. Lundbeck A/S, Copenhagen, Denmark. Electronic address: laba@lundbeck.com.
authors.forename: Lassina
authors.initials: L
authors.lastname: Badolo
mesh_terms: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000145:classification / Q000378:metabolism*; D000595:Amino Acid Sequence; D000818:Animals; D006110:Grasshoppers; D008954:Models, Biological; D008969:Molecular Sequence Data; D010802:Phylogeny; D017386:Sequence Homology, Amino Acid; D059467:Transcriptome
chemical_list: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1
keywords: Blood brain barrier; Functional characterization; Invertebrate in situ model; P-gp efflux transporter; Transcriptome analysis