Maul Raymond S, Song Yuhong, Amann Kurt J, Gerbin Sachi C, Pollard Thomas D, Chang David D
Department of Medicine, Immunology, and Molecular Genetics, University of California, Los Angeles, Los Angeles, CA 90095, USA.
J Cell Biol. 2003 Feb 3;160(3):399-407. doi: 10.1083/jcb.200212057.
Epithelial protein lost in neoplasm (EPLIN) is a cytoskeleton-associated protein encoded by a gene that is down-regulated in transformed cells. EPLIN increases the number and size of actin stress fibers and inhibits membrane ruffling induced by Rac. EPLIN has at least two actin binding sites. Purified recombinant EPLIN inhibits actin filament depolymerization and cross-links filaments in bundles. EPLIN does not affect the kinetics of spontaneous actin polymerization or elongation at the barbed end, but inhibits branching nucleation of actin filaments by Arp2/3 complex. Side binding activity may stabilize filaments and account for the inhibition of nucleation mediated by Arp2/3 complex. We propose that EPLIN promotes the formation of stable actin filament structures such as stress fibers at the expense of more dynamic actin filament structures such as membrane ruffles. Reduced expression of EPLIN may contribute to the motility of invasive tumor cells.
肿瘤中丢失的上皮蛋白（EPLIN）是一种与细胞骨架相关的蛋白质，由一个在转化细胞中下调的基因编码。EPLIN增加肌动蛋白应力纤维的数量和大小，并抑制Rac诱导的膜皱褶。EPLIN至少有两个肌动蛋白结合位点。纯化的重组EPLIN抑制肌动蛋白丝解聚并使丝交联成束。EPLIN不影响肌动蛋白自发聚合的动力学或在带刺末端的伸长，但抑制Arp2/3复合物介导的肌动蛋白丝分支成核。侧链结合活性可能稳定丝，并解释了Arp2/3复合物介导的成核抑制。我们提出，EPLIN以牺牲更动态的肌动蛋白丝结构（如膜皱褶）为代价，促进稳定的肌动蛋白丝结构（如应力纤维）的形成。EPLIN表达降低可能有助于侵袭性肿瘤细胞的运动。
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