Open Access Research article

Validation of microarray data in human lymphoblasts shows a role of the ubiquitin-proteasome system and NF-kB in the pathogenesis of Down syndrome

Barbara Granese1, Iris Scala1, Carmen Spatuzza2, Anna Valentino1, Marcella Coletta1, Rosa Anna Vacca3, Pasquale De Luca4 and Generoso Andria1*

  • * Corresponding author: Generoso Andria andria@unina.it

  • † Equal contributors

Author Affiliations

1 Department of Pediatrics, Federico II University, Naples 80131, Italy

2 Department of Biotechnological Sciences, Federico II University, Naples 80131, Italy

3 Institute of Biomembranes and Bioenergetics, National Council of Research, Bari 70126, Italy

4 Stazione Zoologica “A. Dohrn”, c/o BioGeM, Via Camporeale, Ariano Irpino 83031, Italy

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BMC Medical Genomics 2013, 6:24  doi:10.1186/1755-8794-6-24

Published: 5 July 2013

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.

Keywords:
Down syndrome; Trisomy 21; Expression; Ubiquitin-proteasome system; NF-kB