Geometry of the nuclear envelope determines its flexural stiffness.
Geometry of the nuclear envelope determines its flexural stiffness.
复制标题
DOI：
10.1091/mbc.e20-02-0163
复制
发表时间：
2020-07-21
影响因子：
3.3
通讯作者：
Lele TP
中科院分区：
文献类型：
--
作者：
Agrawal A;Lele TP
在裂变酵母的闭合有丝分裂过程中，不断生长的微管推到核膜上使其变形，这导致裂变成两个子核。由弯曲刚度量化的包膜对弯曲的抵抗力有助于确定微管依赖的核形状转变。信封力学的计算模型已经假设了基于简单的缩放参数的信封的弯曲刚度值。然而，由于核膜的复杂结构，这些估计的有效性值得怀疑。在这里，我们进行了计算分析的弯曲核包膜下施加的力使用的模型，占信封的几何形状。我们的计算表明，核被膜的有效弯曲模量是一个数量级大于一个单一的膜和大约五倍大于核层。这种大的弯曲模量部分是由于两个膜之间的45 nm间隔，这在结构中支持更大的弯曲力矩。此外，有效的弯曲模量是高度敏感的核包膜的几何形状，从两倍到一个数量级大于相应的单膜。这些结果表明，空间的变化，在几何形状和力学环境的包膜可能会导致空间分布的弯曲刚度在同一个核。总的来说，我们的计算支持的可能性，核膜可以平衡显着的机械应力在酵母和细胞从高等生物。
During closed mitosis in fission yeast, growing microtubules push onto the nuclear envelope to deform it, which results in fission into two daughter nuclei. The resistance of the envelope to bending, quantified by the flexural stiffness, helps determine the microtubule-dependent nuclear shape transformations. Computational models of envelope mechanics have assumed values of the flexural stiffness of the envelope based on simple scaling arguments. The validity of these estimates is in doubt, however, owing to the complex structure of the nuclear envelope. Here, we performed computational analysis of the bending of the nuclear envelope under applied force using a model that accounts for envelope geometry. Our calculations show that the effective bending modulus of the nuclear envelope is an order of magnitude larger than a single membrane and approximately five times greater than the nuclear lamina. This large bending modulus is in part due to the 45 nm separation between the two membranes, which supports larger bending moments in the structure. Further, the effective bending modulus is highly sensitive to the geometry of the nuclear envelope, ranging from twofold to an order magnitude larger than the corresponding single membrane. These results suggest that spatial variations in geometry and mechanical environment of the envelope may cause a spatial distribution of flexural stiffness in the same nucleus. Overall, our calculations support the possibility that the nuclear envelope may balance significant mechanical stresses in yeast and in cells from higher organisms.