Home | Help | Feedback | Subscriptions | Archive | Search | Table of Contents

This Article Full Text (PDF, 294K) PPT slides of all figures Alert me when this article is cited Services Email this article Similar articles in this journal Alert me to new content in the JCB Download to citation manager Citing Articles Citing Articles via CrossRef Citing Articles via Google Scholar Google Scholar Articles by Dove, A. W. Search for Related Content PubMed Articles by Dove, A. W. Social Bookmarking                            What's this?

© The Rockefeller University Press, 0021-9525/2002/9/1153-b $5.00
The Journal of Cell Biology, Volume 158, Number 7, September 30, 2002 1153-b-1153

An endosomal switchboard

TGFß signaling (green) takes place in endosomes (red).

Studies on the internalization of signaling receptors generally suggest that receptor endocytosis attenuates signaling. On page 1239, Hayes et al. turn this concept on its head, showing that inhibiting endocytosis actually impairs TGFß receptor signaling. The findings suggest that endosomes may in fact serve as specialized signaling compartments that amplify and propagate certain types of cellular signals.

The authors found that the endogenous TGFß receptor in cultured cells localizes to endosomes containing the early endosomal marker EEA1. SARA, a soluble cytoplasmic protein required for TGFß function, is found almost exclusively in the same EEA1-enriched endosomes. Disrupting TGFß receptor endocytosis impairs downstream signaling events normally mediated by the receptor. This result is reminiscent of the disruption of antiapoptotic signaling recently noted in cells that lack clathrin function (Wettey, F.R., et al. 2002. Science 297:1521–1525).

This is the first time membrane trafficking has been shown to be required for the productive association of two components of a signaling pathway, and it suggests that the function of the endosome in signaling may need to be reevaluated. Hayes et al. propose two models to explain their results: either SARA and other signaling components are restricted to the endosome, requiring TGFß receptor internalization to form the signaling complex, or the TGFß receptor signaling complex forms at the plasma membrane, but requires the biochemical conditions of the endosome to produce a signal.

Alan W. Dove

alanwdove{at}earthlink.net

CiteULike    Complore    Connotea    Del.icio.us    Digg    Facebook    Reddit    Technorati    Twitter    What's this?

This Article Full Text (PDF, 294K) PPT slides of all figures Alert me when this article is cited Services Email this article Similar articles in this journal Alert me to new content in the JCB Download to citation manager Citing Articles Citing Articles via CrossRef Citing Articles via Google Scholar Google Scholar Articles by Dove, A. W. Search for Related Content PubMed Articles by Dove, A. W. Social Bookmarking                            What's this?