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Activation of mitogen-activated protein kinase by cholinergic agonists and EGF in human compared with rat cultured

Yoshitaka Horikawa1, Marie A Shatos, Robin R Hodges

  • 1Schepens Eye Research Institute, Harvard Medical School, Boston, Massachusetts 02114, USA.

Investigative Ophthalmology & Visual Science
|May 27, 2003
PubMed
Abstract

Insights

Cholinergic agonists and epidermal growth factor (EGF) activate mitogen-activated protein kinase (MAPK) in goblet cells. This receptor-mediated activation suggests rats can model human conjunctival goblet cell responses.

Area of Science:

  • Cell biology
  • Molecular signaling
  • Ocular surface research

Background:

  • Goblet cells in the conjunctiva are crucial for ocular surface health.
  • Mitogen-activated protein kinase (MAPK) pathways regulate cellular responses.
  • Understanding signaling pathways in goblet cells is vital for treating ocular surface diseases.

Purpose of the Study:

  • To compare the activation of p42/p44 MAPK by cholinergic agonists and EGF in human and rat conjunctival goblet cells.
  • To investigate the receptor-mediated mechanisms of MAPK activation.
  • To determine if rat goblet cells can serve as a model for human goblet cells.

Main Methods:

  • Primary cultures of human and rat conjunctival goblet cells were established.
  • Cells were stimulated with carbachol (cholinergic agonist) or EGF.
  • Inhibition studies used EGF receptor (EGFR) and muscarinic M(3) receptor antagonists.
  • Protein activation was assessed by Western blot analysis for phosphorylated p42/p44-MAPK.

Main Results:

  • Both carbachol and EGF induced a time-dependent increase in MAPK activity in goblet cells from both species.
  • EGF maximally activated MAPK at 5 minutes, while carbachol showed maximum activation at 10 minutes.
  • Inhibition of EGFR (AG1478) and M(3) receptors (4-DAMP) completely blocked MAPK activation by carbachol and EGF, respectively.
  • Cholinergic agonists were found to transactivate the EGF receptor.

Conclusions:

  • Cholinergic agonists and EGF activate MAPK in conjunctival goblet cells via receptor-mediated pathways.
  • Cholinergic agonists transactivate the EGF receptor in these cells.
  • Cultured rat conjunctival goblet cells provide a suitable model for studying human goblet cell responses to these stimuli.

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