Mechanisms of proliferation synergy by receptor tyrosine kinase and G protein-coupled receptor activation in human airway smooth muscle

V. P. Krymskaya, M. J. Orsini, A. J. Eszterhas, K. C. Brodbeck, J. L. Benovic, Jr Panettieri, R. B. Penn

Research output: Contribution to journalArticlepeer-review

113 Scopus citations


Despite recent studies depicting the capacity of G protein-coupled receptors (GPCRs) to activate mitogenic signaling pathways more commonly associated with receptor tyrosine kinases (RTKs), little is known regarding the interactive effects of GPCR and RTK activation on cell growth and signal transduction. Such interactions likely mediate the physiologic growth in most cells in vivo as well as the aberrant, non-neoplastic growth that occurs in diseases such as asthma, where disruptions of the local hormonal or inflammatory state can contribute to significant GPCR activation. In this study, we show that numerous inflammatory or contractile agents, including thrombin, histamine, and carbachol, potentiate epidermal growth factor (EGF)-stimulated proliferation of human airway smooth muscle (ASM), thus demonstrating a clear synergy between RTK and GPCR activation. Alterations in promitogenic nuclear signaling were evidenced by additive or synergistic increases in Elk-1 and activator protein-1 activation, and by increases in cyclin D1 expression. Interestingly, GPCR activation did not cause EGF receptor tyrosine phosphorylation nor did it increase EGF-stimulated autophosphorylation. In the presence of EGF, histamine or carbachol did not alter the time-dependent phosphorylation of p42/p44, whereas thrombin was capable of increasing phospho-p42/p44 levels at selected time points in some, but not all, cultures. In contrast to their relative inability to alter EGF receptor-linked p42/p44 activation, thrombin, histamine, and carbachol consistently increased the late phase (> 1 h) activity of p70 S6 kinase. Collectively, these findings suggest that inflammatory and contractile agents that activate GPCRS can significantly modulate RTK-mediated ASM growth through a p70 S6 kinase-dependent, p42/p44-independent mechanism.

Original languageAmerican English
Pages (from-to)546-554
Number of pages9
JournalAmerican journal of respiratory cell and molecular biology
Issue number4
StatePublished - 2000
Externally publishedYes

ASJC Scopus subject areas

  • Molecular Biology
  • Pulmonary and Respiratory Medicine
  • Clinical Biochemistry
  • Cell Biology


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