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Inhibition of protein tyrosine phosphatase activity blocks shape change & steroidogenesis in Y1 cells

B J Whitehouse1, S L Gyles, C J Burns

  • 1Endocrinology & Reproduction Research Group, School of Biomedical Sciences, King's College London.

Endocrine Research
|February 24, 2001
PubMed

Insights

Forskolin stimulates steroid secretion and cell rounding in Y1 cells, involving paxillin dephosphorylation. A tyrosine phosphatase inhibitor, calpeptin, blocks these responses, indicating phosphatase involvement in cyclic AMP-stimulated steroidogenesis.

Area of Science:

  • Cell Biology
  • Endocrinology
  • Biochemistry

Background:

  • Y1 adrenocortical cells exhibit shape changes and increased steroid secretion upon forskolin stimulation.
  • This forskolin-induced cell rounding is linked to the dephosphorylation of paxillin, a focal adhesion protein.

Purpose of the Study:

  • To investigate the role of tyrosine phosphatase activity in forskolin-induced steroidogenesis and shape change in Y1 cells.
  • To determine the effect of the tyrosine phosphatase inhibitor calpeptin on these cellular responses.

Main Methods:

  • Y1 cells were treated with forskolin (FSK) and/or calpeptin (CP).
  • Cell shape changes (rounding) and steroid secretion were quantified.
  • Steroid production from a membrane-permeant precursor was assessed to control for general steroidogenic capacity.

Main Results:

  • Forskolin significantly increased cell rounding and steroid secretion.
  • Calpeptin pretreatment partially blocked forskolin-induced cell rounding.
  • Calpeptin abolished the forskolin-stimulated steroidogenic response without affecting basal steroid production.

Conclusions:

  • Tyrosine phosphatase activity is implicated in the cyclic AMP-mediated steroidogenesis in Y1 cells.
  • Paxillin dephosphorylation is crucial for the cell rounding response to forskolin.
  • Inhibition of tyrosine phosphatases disrupts steroidogenesis in response to forskolin stimulation.

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