My 2008 Cover Paper is online now ......

Update 2008-10-2, Listed as a Featured Article in Cell Migration Gateway.

Updated 2008-9-21, F1000 review is on:

Pekka Lappalainen
Institute of Biotechnology, Finland
Cell Biology

Hypothesis
New Finding

This outstanding study demonstrates that coronin-1B coordinates actin dynamics within lamellipodia by remodeling Arp2/3-complex-induced actin filament branches. By using a wide array of biochemical and cell biological methods, Cai et al. revealed that coronin-1B and cortactin antagonize each other in vitro and in cells. Whereas cortactin protects Arp2/3-containing actin filament branches from disassembly, coronin-1B displaces Arp2/3 from filament branches. Subsequent coronin-1B branches have more variable angle and are less stable as compared to Arp2/3 branches. Furthermore, the authors propose that ADF/cofilins may disassemble coronin-1B branches in cells.

Competing interests: None declared
Evaluated 16 Sep 2008

Introduction on Cell Leading Edge - In This Issue

Actin Branches Dethroned by Coronin
PAGE 828

Leading edge protrusion, endocytosis, and intracellular junction formation all require the formation of branched actin networks that are generated by the Arp2/3 complex. Cai et al. present evidence that Coronin 1B can trigger disassembly of Arp2/3 branches in a manner that is antagonistic with Cortactin. Coronin 1B can also replace the Arp2/3 complex at branch junctions and generate a new branched actin network with altered structural properties. While the formation of these networks has been extensively studied, the results now elucidate the remodeling and ultimate recycling of the Arp2/3 branched actin network.

Abstract is:

Cell. 2008 Sep 5;134(5):828-42.
Coronin 1B Antagonizes Cortactin and Remodels Arp2/3-Containing Actin Branches in Lamellipodia.
Cai L, Makhov AM, Schafer DA, Bear JE.
Department of Cell and Developmental Biology, Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-7295, USA.

The dendritic actin network generated by the Arp2/3 complex in lamellipodia underlies formation of protrusions, directional sensing, and migration. While the generation of this network is well studied, the mechanisms regulating network disassembly are poorly understood. We report that Coronin 1B disassembles Arp2/3-containing actin filament branches by inducing Arp2/3 dissociation. This activity is antagonized by Cortactin, a filament branch stabilizer. Consistent with this biochemical competition, depletion of both proteins partially rescues defects in lamellipodial dynamics observed upon depletion of either protein alone. Coronin 1B targets actin branches in a manner that is mutually exclusive with the Arp2/3 complex and alters the branch angle. We conclude that Coronin 1B replaces the Arp2/3 complex at actin filament branches as the dendritic network matures and drives the turnover of branched actin networks.

PMID: 18775315

And the cover is:

Coronin Remodels Actin Branches
"On the cover: Coronins are highly conserved actin-binding proteins that localize to the leading edge of motile cells. In this issue, Cai et al. (pp. 828–842) describe the mechanism of Coronin 1B function. This protein can target actin filament branches generated by the Arp2/3 complex, replace this complex, and produce a remodeled branch with altered geometry. This activity is antagonized by Cortactin, an actin-binding adaptor protein that protects the branches from disassembly. The illustration is an artistically rendered version of a dual-color kymograph used to demonstrate the temporal sequence of branch remodeling in the lamellipodia."

Small story from the insider:
We submitted the following four candidates to compete for the cover.

#1 shows different actin filament angles in vitro formed by purified proteins

#2 is a platinum replica EM of the leading edge of a migration cells, on top pseudo colored with dots suggesting two types of actin branches

#3 is an example of kymograph, suggesting the synchronization between Cortactin (in blue) and Arp2/3 (in green) in the leading edge and the spacial-temporal gradient flows of Coronin 1B (red) and Arp2/3

#4 is the model of Coronin action, which is on the analogy of falling leaves

And what was chosen is up the front of this post.