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Inhibition of cellular response to platelet-derived growth factor by low M(r) phosphotyrosine protein phosphatase

A Berti1, S Rigacci, G Raugei

  • 1Dipartimento di Scienze Biochimiche, Università di Firenze, Florence, Italy.

FEBS Letters
|July 25, 1994
PubMed

Insights

Low molecular weight phosphotyrosine protein phosphatase (PTPase) significantly inhibits cell proliferation stimulated by platelet-derived growth factor (PDGF). This cytosolic enzyme also reduces PDGF receptor autophosphorylation, impacting cellular signaling pathways.

Area of Science:

  • Cell Biology
  • Molecular Biology
  • Biochemistry

Background:

  • Cell proliferation is a fundamental biological process.
  • Platelet-derived growth factor (PDGF) is a key mitogen regulating cell growth.
  • Phosphotyrosine protein phosphatases (PTPases) are crucial in signal transduction pathways.

Purpose of the Study:

  • To investigate the role of low molecular weight (M(r)) PTPase in controlling NIH/3T3 fibroblast cell proliferation.
  • To determine the effect of PTPase expression on cellular responses to PDGF stimulation.
  • To analyze the impact of PTPase on PDGF receptor autophosphorylation.

Main Methods:

  • Transfection and expression of a synthetic gene encoding low M(r) PTPase in NIH/3T3 fibroblasts.
  • Stimulation of transfected cells with PDGF and fetal calf serum.
  • Quantification of mitogenic response and PDGF receptor autophosphorylation levels.

Main Results:

  • Expression of low M(r) PTPase significantly decreased the mitogenic response to PDGF by up to 90%.
  • The inhibitory effect on cell proliferation was more pronounced with PDGF stimulation compared to fetal calf serum.
  • Hormone-dependent autophosphorylation of the PDGF receptor was substantially reduced in cells expressing PTPase.

Conclusions:

  • Low M(r) PTPase, a cytosolic enzyme, plays a critical role in regulating cell proliferation.
  • PTPase activity directly impacts cellular responses mediated by PDGF signaling.
  • The enzyme effectively inhibits PDGF receptor autophosphorylation, modulating downstream signaling events.

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