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

This Article 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 LeBrasseur, N. Search for Related Content PubMed Articles by LeBrasseur, N. Related Collections Related Article Social Bookmarking                            What's this?

Par-3 for the cofilin course

Tight junctions (top) disassemble without Par-3 (middle) but are rescued by active cofilin (bottom).

On page 671, Chen and Macara unveil a mechanism by which Par-3 orchestrates cell polarization by regulating actin reorganization.

Par-3 is one member of an apical polarity-inducing complex that also includes Par-6 and aPKC. The Par proteins are well-known for protein–protein interactions, but how these interactions lead to polarization is less clear. Using RNAi, Chen and Macara had previously shown that Par-3 helps assemble tight junctions (TJs) in epithelial cells by inhibiting an activator of Rac. The study now reveals a second function of Par-3 at TJs.

In the previous work, the authors saw that TJ formation required actin reorganization, so Chen looked for any effects of Par-3 on actin regulators. He now finds that cofilin, an actin filament severing protein, is phosphorylated and thus inactivated in the absence of Par-3.

The inactivation of cofilin in the Par-3 RNAi cells is due to overactive LIMK2, which is one of several kinases that modifies cofilin. Par-3 binds to LIMK2 and inhibits its kinase activity. By doing so at TJs, where the Par complex is localized, Par-3 would keep cofilin active, thus driving actin reorganization.

Par-3 and LIMK2 are widely expressed, so Chen suspects that actin might be regulated by these proteins in other cell types. He is currently examining whether migrating cells require Par-3 to block LIMK2 at the leading edge, where actin turnover is needed.

Nicole LeBrasseur

lebrasn{at}rockefeller.edu

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

Related Article

Par-3 mediates the inhibition of LIM kinase 2 to regulate cofilin phosphorylation and tight junction assembly

Xinyu Chen and Ian G. Macara
J. Cell Biol. 2006 172: 671-678. [Abstract] [Full Text] [PDF]

This Article 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 LeBrasseur, N. Search for Related Content PubMed Articles by LeBrasseur, N. Related Collections Related Article Social Bookmarking                            What's this?