Protein tyrosine phosphatase-η expression is upregulated by the PKA- dependent and is downregulated by the PKC-dependent pathways in thyroid cells

Maria Luisa Martelli, Francesco Trapasso, Paola Bruni, Maria Teresa Berlingieri, Caterina Battaglia, Maria Teresa Vento, Barbara Belletti, Rodolfo Iuliano, Massimo Santoro, Giuseppe Viglietto, Alfredo Fusco

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Abstract

We have recently reported the isolation of a rat cDNA encoding a receptor-type tyrosine phosphatase, which appears to be a marker of thyroid differentiation. To elucidate the molecular mechanisms underlying r-PTPη expression in normal thyroid cells both in vitro and in vivo, we investigated the regulation of r-PTPη expression in cultured thyrocytes (the rat cell line PC C13) and in an animal model of TSH-dependent thyroid goitrogenesis. In vitro studies showed that mRNA expression of r-PTPη in thyroid cells is induced in a time- and dose-dependent manner by the activation of growth- and differentiation-linked PKA pathways (TSH and forskolin), whereas it is down- regulated by the activation of the proliferative dedifferentiating PKC- dependent transduction pathway (TPA). However, the regulation of r-PTPη expression by TSH and TPA, respectively, is observed only in normal thyroid cells, but is lost in transformed thyroid cells. In vivo studies with thiouracil-fed rats demonstrated that increased serum levels of TSH up- regulated r-PTPη mRNA expression in parallel with the stimulation of thyroid growth and function. The reduction of blood TSH levels due to iodide refeeding to goitrous rats determined a marked down-regulation of r-PTPη expression, in parallel with involution of thyroid hyperplasia. Taken together these results demonstrate that the phosphatase r-PTPη is regulated by the two main thyroid regulatory pathways and suggest that it may play an important role in the growth and differentiation of thyroid cells.

Original languageEnglish
Pages (from-to)195-202
Number of pages8
JournalExperimental Cell Research
Volume245
Issue number1
DOIs
Publication statusPublished - Nov 25 1998

Keywords

  • Differentiation
  • Thyroid cell
  • Tyrosine phosphatase

ASJC Scopus subject areas

  • Cell Biology

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    Martelli, M. L., Trapasso, F., Bruni, P., Berlingieri, M. T., Battaglia, C., Vento, M. T., Belletti, B., Iuliano, R., Santoro, M., Viglietto, G., & Fusco, A. (1998). Protein tyrosine phosphatase-η expression is upregulated by the PKA- dependent and is downregulated by the PKC-dependent pathways in thyroid cells. Experimental Cell Research, 245(1), 195-202. https://doi.org/10.1006/excr.1998.4257