Retinoblastoma protein acts as Pax 8 transcriptional coactivator

Stefania Miccadei, Claudia Provenzano, Martin Mojzisek, Pier Giorgio Natali, Donato Civitareale

Research output: Contribution to journalArticlepeer-review


Control of cell proliferation and differentiation by the retinoblastoma protein (pRb) depends on its interactions with key cellular substrates. Available data indicate that pRb and the transcription factor Pax 8 play a crucial role in the differentiation of thyroid follicular cells. In this study, we show that pRb takes part in the complex assembled on the thyroperoxidase gene promoter acting as a transcriptional coactivator of Pax 8. Accordingly, pRb interacts with and potentiates Pax 8 transcriptional activity. In addition, we show that the downregulation of pRb gene expression, in thyrocytes, through RNA interference results in a reduction of the thyroperoxidase gene promoter activity mediated by the Pax 8-binding site. In agreement with these results and with the ability of the adenoviral protein E1A to bind pRb, we show that E1A downregulates Pax 8 activity and that such inhibition requires the E1A-Rb interaction. Furthermore, we show that the Pax 8/pRb synergy plays a role on the sodium/iodide symporter gene expression as well.

Original languageEnglish
Pages (from-to)6993-7001
Number of pages9
Issue number47
Publication statusPublished - Oct 27 2005


  • Coactivator
  • Pax 8
  • Retinoblastoma protein
  • Thyroid
  • Transcription

ASJC Scopus subject areas

  • Molecular Biology
  • Cancer Research
  • Genetics


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