Cell Biology

Spatial Properties of EGF Signals

Science's STKE  09 Sep 2003:
Vol. 2003, Issue 199, pp. tw347-TW347
DOI: 10.1126/stke.2003.199.tw347

Restriction of signals within spatial domains or the opposite--spreading of a signal throughout a cell--can fundamentally alter the consequences of activation of a particular signaling pathway. For example, some signals from localized activation of epidermal growth factor (EGF) receptors are propagated throughout the cell. However, some cells respond to chemotactic gradients of EGF, which means that asymmetric signals must be present. To explore this conundrum, Kempiak et al. applied localized stimulation with EGF to rat mammary adenocarcinoma cells by linking EGF to magnetic beads. They then observed spatial properties of a range of signaling responses. Staining for phosphotyrosine was restricted to a radius of about 1 μm, the size of the EGF-coated bead. Reorganization of the actin cytoskeleton and phosphorylated Akt (a protein kinase) was more broadly disseminated and extended about 0.5 μm beyond the activated receptors. Activation of the mitogen-activated protein kinase ERK2, on the other hand, was detected throughout the cell (spreading about 10 μm). The findings support theories that propose existence of such short- and long-range signals as a mechanism by which cells respond to small differences in concentration of chemotactic agents.

S. J. Kempiak, S.-C. Yip, J. M. Backer, J. E. Segall, Local signaling by the EGF receptor. J. Cell Biol. 162, 781-788 (2003). [Abstract] [Full Text]