Miao Long, Vanderlinde Orion, Liu Jun, Grant Richard P, Wouterse Alan, Shimabukuro Katsuya, Philipse Albert, Stewart Murray, Roberts Thomas M
Department of Biological Science and Institute of Molecular Biophysics, Florida State University, Tallahassee, FL 32306, USA.
Proc Natl Acad Sci U S A. 2008 Apr 8;105(14):5390-5. doi: 10.1073/pnas.0708416105. Epub 2008 Apr 2.
Although several models have been proposed to account for how cytoskeleton polymerization drives protrusion in cell motility, the precise mechanism remains controversial. Here, we show that, in addition to force exerted directly against the membrane by growing filaments, the way elongating filaments pack also contributes to protrusion by generating an expansion of the cytoskeleton gel. Tomography shows that filament packing in the major sperm protein (MSP) -based nematode sperm-motility machinery resembles that observed with rigid rods. Maximum rod-packing density decreases dramatically as the rods lengthen. Therefore, as filaments elongate, the cytoskeleton gel expands to accommodate their packing less densely. This volume expansion combines with polymerization to drive protrusion. Consistent with this hypothesis, an engineered MSP mutant that generates shorter filaments shows higher filament-packing density and slower movement.
尽管已经提出了几种模型来解释细胞骨架聚合如何驱动细胞运动中的突起，但精确机制仍存在争议。在这里，我们表明，除了生长的细丝直接作用于膜的力之外，伸长的细丝的堆积方式也通过产生细胞骨架凝胶的膨胀而有助于突起。断层扫描显示，基于主要精子蛋白（MSP）的线虫精子运动机制中的细丝堆积类似于用刚性杆观察到的情况。随着杆的延长，最大杆堆积密度急剧下降。因此，随着细丝伸长，细胞骨架凝胶膨胀以适应其较疏松的堆积。这种体积膨胀与聚合作用相结合以驱动突起。与该假设一致，产生较短细丝的工程化MSP突变体显示出更高的细丝堆积密度和更慢的运动。
