Epidermal Growth Factor Receptor Translocation to the Mitochondria

Icksoo Lee,Robert Davidson,Michelle L. Demory,Robert Douglas,Sarah J. Parsons,Julie L. Boerner,Tsuyoshi Miyake,William Faust,Gabriel Haddad,Maik Hüttemann

doi:10.1074/jbc.m109.000760

Abstract

Co-overexpression of the epidermal growth factor (EGF) receptor (EGFR) and c-Src frequently occurs in human tumors and is linked to enhanced tumor growth. In experimental systems this synergistic growth requires EGF-dependent association of c-Src with the EGFR and phosphorylation of Tyr-845 of the receptor by c-Src. A search for signaling mediators of Tyr(P)-845 revealed that mitochondrial cytochrome c oxidase subunit II (CoxII) binds EGFR in a Tyr(P)-845- and EGF-dependent manner. In cells this association involves translocation of EGFR to the mitochondria, but regulation of this process is ill-defined. The current study demonstrates that c-Src translocates to the mitochondria with similar kinetics as EGFR and that the catalytic activity of EGFR and c-Src as well as endocytosis and a mitochondrial localization signal are required for these events. CoxII can be phosphorylated by EGFR and c-Src, and EGF stimulation reduces Cox activity and cellular ATP, an event that is dependent in large part on EGFR localized to the mitochondria. These findings suggest EGFR plays a novel role in modulating mitochondrial function via its association with, and modification of CoxII.

Highlights

The epidermal growth factor receptor (EGFR)2 is overexpressed in many cancers including breast cancers, where its overexpression is associated with a poor prognosis [1, 2], yet EGFR alone when overexpressed in fibroblasts is a weak onco
Quantification revealed that EGFR co-localized with the mitochondria in 30% of cells (Fig. 1B), and 5–10% of the total receptor in the cell was found in this compartment (Fig. 2D)
These results indicate that c-Src overexpression and kinase activity enhance EGFR translocation to the mitochondria. c-Src Translocation Is Promoted by the Kinase Activities of EGFR and c-Src and Overexpressed EGFR— Because c-Src and EGFR expression levels and kinase activities regulate after EGF stimulation was tracked in 10T1/2 cells co-overex- the frequency of EGFR seen at the mitochondria, we asked what pressing EGFR and c-Src

Summary

Epidermal Growth Factor Receptor Translocation to the Mitochondria

CoxII can be phosphorylated by EGFR and c-Src, and EGF stimulation reduces Cox activity and cellular ATP, an event that is dependent in large part on EGFR localized to the mitochondria These findings suggest EGFR plays a novel role in modulating mitochondrial function via its association with, and modification of CoxII. It has been suggested that expression and activity [11] or protein-protein associations [12] of Cox subunits may regulate cytochrome c release from the mitochondria during apoptosis In support of this idea, Boerner et al [9] observed an increase in apoptosis in adriamycin-treated breast cancer cells expressing a mutant Y845F EGFR as compared with those expressing wild type, stimulated receptor. These findings suggest that EGF stimulation alters mitochondrial function in the same time frame as EGFR-mitochondrial co-localization, events that may have implications for growth factor-mediated regulation of cellular bioenergetics and survival

EXPERIMENTAL PROCEDURES

RESULTS

These data and the central role of

DISCUSSION