Science Division, Biology Program, New York University Abu Dhabi (NYUAD), P.O. Box 129188, Abu Dhabi, United Arab Emirates.
Engineering Division, New York University Abu Dhabi (NYUAD), P.O. Box 129188, Abu Dhabi, United Arab Emirates.
Biochim Biophys Acta Gen Subj. 2018 May;1862(5):1079-1090. doi: 10.1016/j.bbagen.2018.01.021. Epub 2018 Feb 2.
Cell surface mechanics is able to physically and biomechanically affect cell shape and motility, vesicle trafficking and actin dynamics. The biophysical properties of cell surface are strongly influenced by cytoskeletal elements. In mammals, tissue-specific expression of six actin isoforms is thought to confer differential biomechanical properties. However, the relative contribution of actin isoforms to cell surface properties is not well understood. Here, we sought to investigate whether and how the composition of endogenous actin isoforms directly affects the biomechanical features of cell surface and cellular behavior.
We used fibroblasts isolated from wild type (WT), heterozygous (HET) and from knockout (KO) mouse embryos where both β-actin alleles are not functional. We applied a combination of genome-wide analysis and biophysical methods such as RNA-seq and atomic force microscopy.
We found that endogenous β-actin levels are essential in controlling cell surface stiffness and pull-off force, which was not compensated by the up-regulation of other actin isoforms. The variations of surface biophysical features and actin contents were associated with distinct cell behaviors in 2D and 3D WT, HET and KO cell cultures. Since β-actin in WT cells and smooth muscle α-actin up-regulated in KO cells showed different organization patterns, our data support the differential localization and organization as a mechanism to regulate the biophysical properties of cell surface by actin isoforms.
We propose that variations in actin isoforms composition impact on the biophysical features of cell surface and cause the changes in cell behavior.
细胞表面力学能够在物理和生物力学上影响细胞的形状和运动、囊泡运输和肌动蛋白动力学。细胞表面的生物物理特性受到细胞骨架成分的强烈影响。在哺乳动物中，六种肌动蛋白同工型的组织特异性表达被认为赋予了不同的生物力学特性。然而，肌动蛋白同工型对细胞表面特性的相对贡献尚不清楚。在这里，我们试图研究内源性肌动蛋白同工型的组成是否以及如何直接影响细胞表面的生物力学特性和细胞行为。
我们使用从野生型（WT）、杂合型（HET）和敲除（KO）小鼠胚胎中分离的成纤维细胞，其中两个β-肌动蛋白等位基因均无功能。我们应用了全基因组分析和生物物理方法的组合，如 RNA-seq 和原子力显微镜。
我们发现，内源性β-肌动蛋白水平对于控制细胞表面的刚性和拉脱力是必不可少的，而其他肌动蛋白同工型的上调并不能补偿这一点。表面生物物理特征和肌动蛋白含量的变化与 2D 和 3D WT、HET 和 KO 细胞培养中的不同细胞行为相关。由于 WT 细胞中的β-肌动蛋白和 KO 细胞中上调的平滑肌α-肌动蛋白显示出不同的组织模式，我们的数据支持肌动蛋白同工型通过差异定位和组织作为调节细胞表面生物物理特性的机制。
我们提出，肌动蛋白同工型组成的变化影响细胞表面的生物物理特征，并导致细胞行为的变化。
