title: Identification of novel Pax8 targets in FRTL-5 thyroid cells by gene silencing and expression microarray analysis.
abstract: BACKGROUND
  The differentiation program of thyroid follicular cells (TFCs), by far the most abundant cell population of the thyroid gland, relies on the interplay between sequence-specific transcription factors and transcriptional coregulators with the basal transcriptional machinery of the cell. However, the molecular mechanisms leading to the fully differentiated thyrocyte are still the object of intense study. The transcription factor Pax8, a member of the Paired-box gene family, has been demonstrated to be a critical regulator required for proper development and differentiation of thyroid follicular cells. Despite being Pax8 well-characterized with respect to its role in regulating genes involved in thyroid differentiation, genomics approaches aiming at the identification of additional Pax8 targets are lacking and the biological pathways controlled by this transcription factor are largely unknown.
  
  
  RESULTS
  To identify unique downstream targets of Pax8, we investigated the genome-wide effect of Pax8 silencing comparing the transcriptome of silenced versus normal differentiated FRTL-5 thyroid cells. In total, 2815 genes were found modulated 72 h after Pax8 RNAi, induced or repressed. Genes previously reported to be regulated by Pax8 in FRTL-5 cells were confirmed. In addition, novel targets genes involved in functional processes such as DNA replication, anion transport, kinase activity, apoptosis and cellular processes were newly identified. Transcriptome analysis highlighted that Pax8 is a key molecule for thyroid morphogenesis and differentiation.
  
  
  CONCLUSIONS
  This is the first large-scale study aimed at the identification of new genes regulated by Pax8, a master regulator of thyroid development and differentiation. The biological pathways and target genes controlled by Pax8 will have considerable importance to understand thyroid disease progression as well as to set up novel therapeutic strategies.
authors.affiliation: Institute of Experimental Endocrinology and Oncology G. Salvatore (IEOS), National Research Council, Naples, Italy.
authors.forename: Tina
authors.initials: T
authors.lastname: Di Palma
authors.forename: Anna
authors.initials: A
authors.lastname: Conti
authors.forename: Tiziana
authors.initials: T
authors.lastname: de Cristofaro
authors.forename: Serena
authors.initials: S
authors.lastname: Scala
authors.forename: Lucio
authors.initials: L
authors.lastname: Nitsch
authors.forename: Mariastella
authors.initials: M
authors.lastname: Zannini
mesh_terms: D000818:Animals; D001665:Binding Sites; D002460:Cell Line; D047369:Chromatin Immunoprecipitation; D020868:Gene Silencing / Q000502:physiology*; D020411:Oligonucleotide Array Sequence Analysis / Q000379:methods*; D000072636:PAX8 Transcription Factor; D051761:Paired Box Transcription Factors / Q000235:genetics / Q000378:metabolism*; D034622:RNA Interference; D051381:Rats; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013961:Thyroid Gland / Q000378:metabolism*
chemical_list: D000072636:PAX8 Transcription Factor; D051761:Paired Box Transcription Factors; C499497:Pax8 protein, rat