Live dynamics of Dictyostelium cofilin suggests a role in remodeling actin latticework into bundles.
Live dynamics of Dictyostelium cofilin suggests a role in remodeling actin latticework into bundles.
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发表时间：
1997-10
影响因子：
4
通讯作者：
H. Aizawa;Y. Fukui;I. Yahara
中科院分区：
文献类型：
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作者：
H. Aizawa;Y. Fukui;I. Yahara
Cofilin是一种不可或缺的肌动蛋白调节蛋白，代表着广泛存在于各种生物体中的肌动蛋白结合蛋白的Cofilin家族。我们以前的和其他体外研究表明，Cofilin可以加速丝状(F)-肌动蛋白和(α)-肌动蛋白网状结构向束状结构的转化，并且Cofilin的过度表达可以诱导Dictyostelius中F-肌动蛋白束的形成。在此，我们表达了Aequorea绿色荧光蛋白(GFP)-Dictyostelialcofilin融合蛋白，并观察了Cofilin的活动态，以检测Cofilin的生理功能。我们发现，纯化的GFP-cofilin结合到肌动蛋白细丝上，并以与真正的Dictyostelialcofilin类似的方式降低肌动蛋白溶液的表观粘度。表达的GFP-cofilin在细胞质中表现出正常的肌动蛋白结合活性，表现为掺入二甲基亚砜诱导的肌动蛋白棒中。自由移动的细胞在背侧表面形成冠状皮质结构，GFP-cofilin动态组装成皮质下形成的肌动蛋白束。在吞噬过程中，GFP-cofilin聚集成肌动蛋白束，形成于吞噬杯底的区域。在被环状AMP化学激活的细胞中，GFP-cofilin在突出的前沿显示出高度的积聚。当化学吸引被实验改变时，GFP-cofilin向新伪足的重新分配发生在大约30-60秒内。这些结果表明，在体内，Cofilin在皮质肌动蛋白网络快速重塑成束的过程中起着至关重要的作用。
Cofilin, an indispensable, actin-regulating protein represents the 'cofilin family' of actin-binding proteins existing in a wide variety of organisms. Our previous and other in vitro studies have implied that cofilin can accelerate transformation of filamentous (F)-actin and (alpha)-actinin latticework into bundles, and overexpression of cofilin induces formation of F-actin bundles in Dictyostelium. Here we expressed an Aequorea green fluorescent protein (GFP)-Dictyostelium cofilin fusion protein in Dictyostelium, and observed the live dynamics to examine the physiological function of cofilin. We show that purified GFP-cofilin binds to actin filaments and decreases the apparent viscosity of actin solution in a similar manner to authentic Dictyostelium cofilin. Expressed GFP-cofilin exhibits normal actin-binding activities in the cytoplasm as represented by incorporation into the actin rods induced with dimethyl sulfoxide. Free moving cells form a crown-like cortical structure on the dorsal surface, and GFP-cofilin exhibits dynamic assembly into actin bundles being formed beneath the cortex. During phagocytosis, GFP-cofilin accumulates into actin bundles formed in the region underlying the phagocytic cups. In cells chemotactically activated with cyclic AMP, GFP-cofilin exhibits a high level of accumulation in projecting leading edges. When the chemo-attraction is experimentally changed, the redistribution of GFP-cofilin towards the new pseudopod occurs in a matter of 30-60 seconds. These results demonstrate that cofilin plays a crucial role in vivo in rapid remodeling of the cortical actin meshwork into bundles.