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Cell Motil Cytoskeleton 2009 Sep 01;669:679-92. doi: 10.1002/cm.20398.
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Structure and dynamics of an Arp2/3 complex-independent component of the lamellipodial actin network.

Henson JH , Cheung D , Fried CA , Shuster CB , McClellan MK , Voss MK , Sheridan JT , Oldenbourg R .

Sea urchin coelomocytes contain an unusually broad lamellipodial region and have served as a useful model experimental system for studying the process of actin-based retrograde/centripetal flow. In the current study the small molecule drug 2,3-butanedione monoxime (BDM) was employed as a means of delocalizing the Arp2/3 complex from the cell edge in an effort to investigate the Arp2/3 complex-independent aspects of retrograde flow. Digitally-enhanced phase contrast, fluorescence and polarization light microscopy, along with rotary shadow transmission electron microscopy methods demonstrated that BDM treatment resulted in the centripetal displacement of the Arp2/3 complex and the associated dendritic lamellipodial (LP) actin network from the cell edge. In its wake there remained an array of elongate actin filaments organized into concave arcs that displayed retrograde flow at approximately one quarter the normal rate. Actin polymerization inhibitor experiments indicated that these arcs were generated by polymerization at the cell edge, while active myosin-based contraction in BDM treated cells was demonstrated by localization with antiphospho-myosin regulatory light chain (MRLC) antibody, the retraction of the cytoskeleton in the presence of BDM, and the response of the BDM arcs to laser-based severing. The results suggest that BDM treatment reveals an Arp2/3 complex-independent actin structure in coelomocytes consisting of elongate filaments integrated into the LP network and that these filaments represent a potential connection between the LP network and the central cytoskeleton.

PubMed ID: 19530177
PMC ID: PMC2914322
Article link: Cell Motil Cytoskeleton
Grant support: [+]

Genes referenced: actr2 LOC100887844 LOC115919910 LOC578403 LOC590297
Antibodies: FSCN1 Ab1 potekp1 Ab1

References [+] :
Bernstein, Tropomyosin binding to F-actin protects the F-actin from disassembly by brain actin-depolymerizing factor (ADF). 1983, Pubmed