title: Cell array-based intracellular localization screening reveals novel functional features of human chromosome 21 proteins.
abstract: BACKGROUND
  Trisomy of human chromosome 21 (Chr21) results in Down's syndrome, a complex developmental and neurodegenerative disease. Molecular analysis of Down's syndrome, however, poses a particular challenge, because the aneuploid region of Chr21 contains many genes of unknown function. Subcellular localization of human Chr21 proteins may contribute to further understanding of the functions and regulatory mechanisms of the genes that code for these proteins. Following this idea, we used a transfected-cell array technique to perform a rapid and cost-effective analysis of the intracellular distribution of Chr 21 proteins.
  
  
  RESULTS
  We chose 89 genes that were distributed over the majority of 21q, ranging from RBM11 (14.5 Mb) to MCM3AP (46.6 Mb), with part of them expressed aberrantly in the Down's syndrome mouse model. Open reading frames of these genes were cloned into a mammalian expression vector with an amino-terminal His6 tag. All of the constructs were arrayed on glass slides and reverse transfected into HEK293T cells for protein expression. Co-localization detection using a set of organelle markers was carried out for each Chr21 protein. Here, we report the subcellular localization properties of 52 proteins. For 34 of these proteins, their localization is described for the first time. Furthermore, the alteration in cell morphology and growth as a result of protein over-expression for claudin-8 and claudin-14 genes has been characterized.
  
  
  CONCLUSIONS
  The cell array-based protein expression and detection approach is a cost-effective platform for large-scale functional analyses, including protein subcellular localization and cell phenotype screening. The results from this study reveal novel functional features of human Chr21 proteins, which should contribute to further understanding of the molecular pathology of Down's syndrome.
authors.affiliation: Department of Vertebrate Genomics, Max Planck Institute for Molecular Genetics, 14195 Berlin, Germany. yuhuihu@molgen.mpg.de
authors.forename: Yu-Hui
authors.initials: YH
authors.lastname: Hu
authors.forename: Hans-Jörg
authors.initials: HJ
authors.lastname: Warnatz
authors.forename: Dominique
authors.initials: D
authors.lastname: Vanhecke
authors.forename: Florian
authors.initials: F
authors.lastname: Wagner
authors.forename: Andrea
authors.initials: A
authors.lastname: Fiebitz
authors.forename: Sabine
authors.initials: S
authors.lastname: Thamm
authors.forename: Pascal
authors.initials: P
authors.lastname: Kahlem
authors.forename: Hans
authors.initials: H
authors.lastname: Lehrach
authors.forename: Marie-Laure
authors.initials: ML
authors.lastname: Yaspo
authors.forename: Michal
authors.initials: M
authors.lastname: Janitz
mesh_terms: D002453:Cell Cycle; D002467:Cell Nucleus / Q000378:metabolism; D002478:Cells, Cultured; D002891:Chromosomes, Human, Pair 21; D003362:Cost-Benefit Analysis; D003600:Cytosol / Q000378:metabolism; D004314:Down Syndrome / Q000235:genetics / Q000378:metabolism; D004721:Endoplasmic Reticulum / Q000378:metabolism; D006801:Humans; D040081:Protein Array Analysis / Q000379:methods*; D021381:Protein Transport; D022142:Secretory Vesicles / Q000378:metabolism; D015398:Signal Transduction; D046888:Tissue Array Analysis / Q000379:methods*; D014018:Tissue Distribution / Q000235:genetics*; D014162:Transfection