Editors' ChoiceGrowth Factors

FGF Translocation

Science's STKE  03 Sep 2002:
Vol. 2002, Issue 148, pp. tw325
DOI: 10.1126/stke.2002.148.tw325

Although the action of fibroblast growth factor (FGF) through receptors present at the cell surface is well characterized, its activities within the cell have not been clear. Exogenous FGF has been detected in the cytoplasm and nucleus of target cells where intracellular FGF-binding proteins have been identified. However, details regarding its translocation into the intracellular milieu are not known. Malecki et al. report that FGF translocation requires an electrical potential characteristic of vesicular membranes. The authors followed the translocation of exogenous FGF by assessing posttranslation modifications of FGF that would only occur in the cytoplasm and nucleus. Treatment of cells with inhibitors of vacuolar protons pumps blocked these modifications, indicating that membrane potential is somehow required for FGF translocation. Inhibitors of Golgi transport and drugs that disrupt the actin and microtubule cytoskeletons did not affect FGF translocation, indicating that vesicles associated with trafficking through the Golgi, endoplasmic reticulum, early endosomes, and lysosomes are not involved. The authors suggest that FGF translocation may occur through late endosomes.

J. Malecki, A. Wiedlocha, J. Wasche, S. Olsnes, Vesicle transmembrane potential is required for translocation to the cytosol of externally added FGF-1, EMBO J. 21, 4480-4490 (2002). [Abstract] [Full Text]