Requirement for intrinsic protein tyrosine kinase in the immediate and late actions of the EGF receptor

Abstract

The epidermal growth factor (EGF) receptor is a transmembrane glycoprotein of relative molecular mass 170,000 with intrinsic ligand-dependent protein tyrosine kinase activity. Binding of EGF to its receptor activates a number of immediate biochemical processes, such as alterations of intracellular free calcium, pH, and increased transcription of several responsive genes, which usually culminate many hours later in DNA replication and cell division. Abolishing the tyrosine kinase activity of three related oncogenes, v-src, v-mos, and v-fps, eliminates their capacity to transform cell. Several reports have suggested that specific aspects of EGF receptor function are independent of the intrinsic tyrosine kinase activity; however, these studies used an antibody against EGF receptor which failed to activate phosphorylation of exogenous substrates and an insertional mutation in the EGF receptor tyrosine kinase domain which had not been shown to abolish protein kinase activity in cells. Because many transmembrane receptors interact with intrinsic membrane proteins to activate second messenger systems, it is important to resolve experimentally whether mechanisms, in addition to activation of the intrinsic tyrosine kinase activity, mediate some EGF actions. From functional analyses of an EGF receptor containing a single amino-acid mutation at a site required for phosphate transfer from ATP, we conclude that the tyrosine kinase activity of the EGF receptor is essential for the diverse biochemical effects of EGF, including rapid alterations in intracellular calcium, activation of gene transcription, receptor down-regulation and the ultimate stimulatory effects on cell proliferation.

Signal transduction through atypical PKCs, but not the EGF receptor, is necessary for UVC-induced AP-1 activation in immortal murine cells

“…The receptor has intrinsic protein tyrosine kinase activity, which is responsible for many of the pleotropic intracellular e ects (Honegger et al, 1987;Chen et al, 1987). Murine ®broblast B82 is a mouse L cell line that contains no EGF receptors, as assessed by EGF binding as well as by RNA blot analysis (Lin et al, 1986).…”

“…Ligand-induced activation of the receptor results in phosphorylation and activation of a number of substrates, including mitogen-activated protein (MAP) kinase (Carpenter and Cohen, 1991;Eldredge et al, 1994). The intrinsic kinase activity of the EGFR is responsible for many of the pleotropic intracellular e ects (Honegger et al, 1987;Chen et al, 1987). Reports from a number of laboratories have established that UVC irradiation activates signal transduction pathways that extend from the cell membrane (Sachsenmaier et al, 1994;Devary, 1991Devary, , 1993 and feed into common signal transduction pathways whose components are mostly shared among TPA and growth factors (Pelech and Songhere, 1992;Karin and Smeal, 1992).…”

Prolactin modulates phosphorylation, signaling and trafficking of epidermal growth factor receptor in human T47D breast cancer cells

“…We also examined downstream consequences of activation of the SHC and ERK pathways by EGF and PRL in T47D cells by monitoring transactivation of a reporter gene driven by two tandem copies of a c-fos enhancer fragment (the p2FTL plasmid (Chen et al, 1987)) ( Figure 6). This reporter was previously shown to be responsive to EGF and GH treatment in other cell types (Chen et al, 1987;Frank et al, 1995;Kim et al, 1998Kim et al, , 2002.…”

“…This reporter was previously shown to be responsive to EGF and GH treatment in other cell types (Chen et al, 1987;Frank et al, 1995;Kim et al, 1998Kim et al, , 2002. T47D cells were transfected with p2FTL and serum-starved before treatment with vehicle, PRL (500 ng/ml), EGF (1 nM) or cotreatment with PRL and EGF for 16 h. Cell lysates were assayed for luciferase activity.…”

“…c-fos-Luciferase transactivation assay T47D cells (70% confluent in a 100 Â 20 mm dish) were transfected with the plasmid p2FTL containing a luciferase reporter gene driven by two tandem copies of a c-fos enhancer fragment (Chen et al, 1987) using LipofectAMINE Plus reagents (Invitrogen, San Diego, CA, USA). The cells were split into one 12-well plate 18-20 h after transfection and grown overnight in culture medium containing 10% fetal bovine serum.…”