Science Inventory

INHIBITION OF PROTEIN TYROSINE PHOSPHATASE ACTIVITY MEDIATES EPIDERMAL GROWTH FACTOR RECEPTOR SIGNALING IN HUMAN AIRWAY EPITHELIAL CELLS

Citation:

TAL, T., L. M. GRAVES, R. A. SILBAJORIS, P. BROMBERG, W. WU, AND J. M. SAMET. INHIBITION OF PROTEIN TYROSINE PHOSPHATASE ACTIVITY MEDIATES EPIDERMAL GROWTH FACTOR RECEPTOR SIGNALING IN HUMAN AIRWAY EPITHELIAL CELLS. TOXICOLOGICAL AND APPLIED PHARMICOLOGY. Elsevier Science BV, Amsterdam, Netherlands, 214(1):16-23, (2006).

Impact/Purpose:

to elucidate the mechanism of Zn2+-induced EGFR activation in human primary bronchial epithelial cells

Description:

Epidemiological studies have implicated zinc in the toxicity of ambient particulate matter (PM) inhalation. We previously showed that exposure to metal-laden PM inhibits protein tyrosine phosphatase (PTP) activity in human primary bronchial epithelial cells (HAEC) and leads to Src-dependent activation of EGFR signaling in B82 and A431 cells. In order to elucidate the mechanism of Zn2+-induced EGFR activation in HAEC, we treated HAEC with 500 ╡M ZnSO4 for 5-20min and measured the state of activation of EGFR, c-Src and PTPs. Western blots revealed that exposure to Zn2+ results in increased phosphorylation at both trans- and auto-phosphorylation sites in the EGFR. Zn2+ mediated EGFR phosphorylation did not require ligand binding and was ablated by the EGFR kinase inhibitor PD153035, but not by the Src kinase inhibitor PP2. Src activity was inhibited by Zn2+ treatment of HAEC, consistent with Src-independent EGFR transactivation in HAEC exposed to Zn2+. The rate of exogenous EGFR dephosphorylation in lysates of HAEC exposed to Zn2+ or V4+ was significantly diminished. Moreover, exposure of HAEC to Zn2+ also resulted in a significant impairment of dephosphorylation of endogenous EGFR. These data show that Zn2+ -induced activation of EGFR in HAEC involves a loss of PTP activities whose function is to dephosphorylate EGFR in opposition to baseline EGFR kinase activity. These findings also suggest that there are marked cell-type specific differences in the mechanism of EGFR activation induced by Zn2+ exposure.

Record Details:

Record Type: DOCUMENT (JOURNAL/PEER REVIEWED JOURNAL)
Product Published Date: 07/01/2006
Record Last Revised: 07/14/2008
OMB Category: Other
Record ID: 151033

Organization:

U.S. ENVIRONMENTAL PROTECTION AGENCY

OFFICE OF RESEARCH AND DEVELOPMENT

NATIONAL HEALTH AND ENVIRONMENTAL EFFECTS RESEARCH LABORATORY

HUMAN STUDIES DIVISION

CLINICAL RESEARCH BRANCH