Isolated nuclei stiffen in response to low intensity vibration.
Isolated nuclei stiffen in response to low intensity vibration.
复制标题
分离的核因低强度振动而变硬。
DOI：
10.1016/j.jbiomech.2020.110012
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发表时间：
2020-10-09
影响因子：
2.4
通讯作者：
Uzer G
中科院分区：
文献类型：
--
作者：
Newberg J;Schimpf J;Woods K;Loisate S;Davis PH;Uzer G
细胞核是所有细胞活动的中心，它依赖于直接的机械输入及其分子转换器来感知和响应外部刺激。虽然已经表明，分离的细胞核可以适应体外施加的力，但在体内响应生理力的核机械适应的机制仍不清楚。为了研究细胞中的核机械适应性，我们开发了一种基于原子力显微镜（AFM）的程序来探测在应用低强度振动（LIV）后从间充质干细胞（MSC）中分离的活细胞核，以确定核刚度是否由于LIV而增加。结果表明，分离的细胞核平均比LIV之前在完整MSC内测试的细胞核软30%。当在LIV（0.7g，90 Hz，20 min）施加四次（4x）（间隔1h）后分离核时，与非LIV对照相比，分离的核的刚度增加75%。LIV诱导的核硬化需要核骨架和细胞骨架（LINC）复合物的功能性连接体，但不伴随核包膜蛋白LaminA/C或Sun-2水平的增加。虽然耗尽LaminA/C或Sun-1&2导致分离的细胞核中异染色质与核面积比增加47%或39%，但与对照相比，LIV处理的细胞核中异染色质与核面积比降低25%，表明LIV诱导的异染色质结构变化。总的来说，我们的研究结果表明，增加的表观细胞刚度响应于外源性的机械挑战的MSC的形式LIV的部分保留增加的核刚度和异染色质结构的变化。
The nucleus, central to all cellular activity, relies on both direct mechanical input and its molecular transducers to sense and respond to external stimuli. While it has been shown that isolated nuclei can adapt to applied force ex vivo, the mechanisms governing nuclear mechanoadaptation in response to physiologic forces in vivo remain unclear. To investigate nuclear mechanoadaptation in cells, we developed an atomic force microscopy (AFM) based procedure to probe live nuclei isolated from mesenchymal stem cells (MSCs) following the application of low intensity vibration (LIV) to determine whether nuclear stiffness increases as a result of LIV. Results indicated that isolated nuclei were, on average, 30% softer than nuclei tested within intact MSCs prior to LIV. When the nucleus was isolated following LIV (0.7g, 90Hz, 20min) applied four times (4x) separated by 1h intervals, stiffness of isolated nuclei increased 75% compared to non-LIV controls. LIV-induced nuclear stiffening required functional Linker of Nucleoskeleton and Cytoskeleton (LINC) complex, but was not accompanied by increased levels of the nuclear envelope proteins LaminA/C or Sun-2. While depleting LaminA/C or Sun-1&2 resulted in either a 47% or 39% increased heterochromatin to nuclear area ratio in isolated nuclei, the heterochromatin to nuclear area ratio was decreased by 25% in LIV-treated nuclei compared to controls, indicating LIV-induced changes in the heterochromatin structure. Overall, our findings indicate that increased apparent cell stiffness in response to exogenous mechanical challenge of MSCs in the form of LIV is in part retained by increased nuclear stiffness and changes in heterochromatin structure.
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