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

This Article Full Text (PDF, 910K) 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 Bashyam, H. Search for Related Content PubMed Articles by Bashyam, H. Social Bookmarking                            What's this?

Self-eating ERs

In stressed cells, expanded ER membranes are cannibalized by ER-derived autophagosomes. WALTER/PLOS

When under stress, the ER of yeast cells expands greatly in size but also eats its own membrane stacks to form autophagosome-like structures, say Sebastián Bernales, Kent McDonald, and Peter Walter (University of California, San Francisco, CA). The process may cleanse the ER of unfolded proteins that would otherwise clog the secretory pathway.

An overworked ER sends out a distress signal called the unfolded protein response (UPR). The UPR helps the ER cope by increasing its folding capacity, and jettisoning those proteins that are hopelessly misfolded. The authors found that, under UPR-inducing conditions, most stressed cells had ER networks that are fivefold bigger than normal. But their electron micrographs also revealed many cells containing normal-sized ERs along with autophagosome-like structures packed selectively with ER stacks. The outer membranes of these structures were also derived from the ER, suggesting that the ER could be cannibalizing itself to return to normal size. Thus, says Walter, the ER can not only "counter-balance its expansion but also detoxify to improve the cell's chances of survival".

UPR induction of many classical autophagy genes was crucial for cell survival during ER stress. But the sequestration and isolation of unhealthy ER may be more important than its eventual degradation, as cells that lacked a proper degradation system survived under UPR conditions.

It is not yet clear why damaged ER is toxic to cells, or how the ER is labeled for sequestration and packaged so selectively.

Reference:

Bernales, S., et al. 2006. PLoS Biol. doi:10.1371/journal.pbio.0040423.

Hema Bashyam

hbashyam{at}rockefeller.edu

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

This Article Full Text (PDF, 910K) 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 Bashyam, H. Search for Related Content PubMed Articles by Bashyam, H. Social Bookmarking                            What's this?