title: Validation of microarray data in human lymphoblasts shows a role of the ubiquitin-proteasome system and NF-kB in the pathogenesis of Down syndrome.
abstract: BACKGROUND
  Down syndrome (DS) is a complex disorder caused by the trisomy of either the entire, or a critical region of chromosome 21 (21q22.1-22.3). Despite representing the most common cause of mental retardation, the molecular bases of the syndrome are still largely unknown.
  
  
  METHODS
  To better understand the pathogenesis of DS, we analyzed the genome-wide transcription profiles of lymphoblastoid cell lines (LCLs) from six DS and six euploid individuals and investigated differential gene expression and pathway deregulation associated with trisomy 21. Connectivity map and PASS-assisted exploration were used to identify compounds whose molecular signatures counteracted those of DS lymphoblasts and to predict their therapeutic potential. An experimental validation in DS LCLs and fetal fibroblasts was performed for the most deregulated GO categories, i.e. the ubiquitin mediated proteolysis and the NF-kB cascade.
  
  
  RESULTS
  We show, for the first time, that the level of protein ubiquitination is reduced in human DS cell lines and that proteasome activity is increased in both basal conditions and oxidative microenvironment. We also provide the first evidence that NF-kB transcription levels, a paradigm of gene expression control by ubiquitin-mediated degradation, is impaired in DS due to reduced IkB-alfa ubiquitination, increased NF-kB inhibitor (IkB-alfa) and reduced p65 nuclear fraction. Finally, the DSCR1/DYRK1A/NFAT genes were analysed. In human DS LCLs, we confirmed the presence of increased protein levels of DSCR1 and DYRK1A, and showed that the levels of the transcription factor NFATc2 were decreased in DS along with a reduction of its nuclear translocation upon induction of calcium fluxes.
  
  
  CONCLUSIONS
  The present work offers new perspectives to better understand the pathogenesis of DS and suggests a rationale for innovative approaches to treat some pathological conditions associated to DS.
authors.affiliation: Department of Pediatrics, Federico II University, Naples 80131, Italy.
authors.forename: Barbara
authors.initials: B
authors.lastname: Granese
authors.forename: Iris
authors.initials: I
authors.lastname: Scala
authors.forename: Carmen
authors.initials: C
authors.lastname: Spatuzza
authors.forename: Anna
authors.initials: A
authors.lastname: Valentino
authors.forename: Marcella
authors.initials: M
authors.lastname: Coletta
authors.forename: Rosa Anna
authors.initials: RA
authors.lastname: Vacca
authors.forename: Pasquale
authors.initials: P
authors.lastname: De Luca
authors.forename: Generoso
authors.initials: G
authors.lastname: Andria
mesh_terms: D002478:Cells, Cultured; D002891:Chromosomes, Human, Pair 21; D019295:Computational Biology; D004268:DNA-Binding Proteins; D004314:Down Syndrome / Q000378:metabolism* / Q000473:pathology; D015536:Down-Regulation; D005347:Fibroblasts / Q000166:cytology / Q000378:metabolism; D006801:Humans; D020672:I-kappa B Proteins / Q000378:metabolism; D047908:Intracellular Signaling Peptides and Proteins / Q000235:genetics; D008214:Lymphocytes / Q000166:cytology / Q000378:metabolism; D009124:Muscle Proteins / Q000235:genetics; D000072000:NF-KappaB Inhibitor alpha; D016328:NF-kappa B / Q000235:genetics / Q000378:metabolism*; D050778:NFATC Transcription Factors / Q000235:genetics; D020411:Oligonucleotide Array Sequence Analysis; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism*; D017346:Protein Serine-Threonine Kinases / Q000235:genetics; D011505:Protein-Tyrosine Kinases / Q000235:genetics; D051996:Transcription Factor RelA / Q000378:metabolism; D025801:Ubiquitin / Q000378:metabolism*; D054875:Ubiquitination; D000097603:Dyrk Kinases
chemical_list: D004268:DNA-Binding Proteins; D020672:I-kappa B Proteins; D047908:Intracellular Signaling Peptides and Proteins; D009124:Muscle Proteins; D000072000:NF-KappaB Inhibitor alpha; D016328:NF-kappa B; D050778:NFATC Transcription Factors; D046988:Proteasome Endopeptidase Complex; D017346:Protein Serine-Threonine Kinases; D011505:Protein-Tyrosine Kinases; D051996:Transcription Factor RelA; D025801:Ubiquitin; D000097603:Dyrk Kinases; C000606204:NFKBIA protein, human; C108612:RCAN1 protein, human