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Role of epidermal growth factor receptor transactivation in the activation of cytosolic phospholipase A2 in leptin protection of salivary gland acinar cells against ethanol cytotoxicity

100%

Slomiany B. L., Slomiany A.

Journal of Physiology and Pharmacology

2009

tom 60

nr 2

49-55

A pleiotropic hormone, leptin, secreted into saliva by the acinar cells of salivary glands is an important mediator of the processes of oral mucosal defense. Here, we report on the role of epidermal growth factor receptor (EGFR) transactivation in the signaling events that mediate leptin protection of sublingual salivary gland acinar cells against ethanol cytotoxicity. We show that the protective effect of leptin against ethanol cytotoxicity was associated with the increased EGFR protein tyrosine kinase and cytosolic phospholipase A2 (cPLA2) activity, and characterized by a marked increase in matrix metalloproteinase MMP-9 and arachidonic acid (AA) release, and PGE2 generation. The loss in countering capacity of leptin against ethanol cytotoxicity was attained with JAK inhibitor AG490, Src inhibitor PP2, and EGFR inhibitor AG1478, as well as ERK inhibitor PD98059. Moreover, the agents evoked also the inhibition in leptin-induced up-regulation in cPLA2 activity, AA release, and PGE2 generation. The changes caused by leptin in EGFR phosphorylation, MMP-9, and cPLA2 activation were susceptible to suppression by metalloprotease inhibitor GM6001, but the production of MMP-9 was not affected by EGFR inhibitor AG1478 or PKC inhibitor Ro318220. These findings point to the involvement of MMP-9 in the event of leptin-induced EGFR transactivation that results in the signaling cascade leading to cPLA2 activation and up-regulation in PGE2 generation, thus providing new insights into the mechanism of oral mucosal protection against ethanol toxicity.

Secretion of gastric mucus phospholipids in response to beta-adrenergic G protein-coupled receptor activation is mediated by SRC kinase-dependent epidermal growth factor receptor transactivation

100%

Slomiany B. L., Slomiany A.

Journal of Physiology and Pharmacology

2004

tom 55

nr 3

Recent advances in understanding the nature of cellular responses mediated by G protein-coupled receptor (GPCR) activation indicate that integration of the converging regulatory signals into functional cellular pathways requires epidermal growth factor receptor (EGFR) transactivation. In this study, we report that G protein-coupled ß-adrenergic receptor activation leading to stimulation in gastric mucus phospholipid secretion occurs with the involvement of EGFR. Using [14C]choline-labeled gastric mucosal cells in culture, we show that stimulatory effect of ß-adrenergic agonist, isoproterenol, on phospholipid release was subject to a dose-dependent suppression by EGFR kinase inhibitor, PD153035, as well as wortmannin, a specific inhibitor of PI3K. Both inhibitors, moreover, caused the reduction in the gastric mucosal cell phospholipid secretory responses to ß-adrenergic agonist-generated second messenger, cAMP as well as adenyl cyclase activator, forskolin. The gastric mucosal phospholipid secretory responses to isoproterenol, furthermore, were inhibited by PP2, a selective inhibitor of tyrosine kinase Src responsible for ligand-independent EGFR phosphorylation, but not by ERK inhibitor, PD98059. The inhibition of ERK, moreover, did not cause attenuation in phospholipid secretory responses to cAMP and forskolin. The findings underline the central role of EGFR in mediation of gastric mucosal secretory processes, and demonstrate the requirement for Src kinase-dependent EGFR transactivation in regulation of gastric mucosal phospholipid secretion in response to ß-adrenergic GPCR activation.

Ograniczanie wyników

2 Journal of Physiology and Pharmacology

2 Slomiany A.

2 Slomiany B. L.

1 2009

1 2004

Wyniki wyszukiwania

Role of epidermal growth factor receptor transactivation in the activation of cytosolic phospholipase A2 in leptin protection of salivary gland acinar cells against ethanol cytotoxicity

Secretion of gastric mucus phospholipids in response to beta-adrenergic G protein-coupled receptor activation is mediated by SRC kinase-dependent epidermal growth factor receptor transactivation