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段沛言, 刘艺, 林心怡, 等. 细胞外基质硬度通过AMPK调控干细胞线粒体的形态异质性[J]. 四川大学学报(医学版), 2024, 55(1): 47-52. DOI: 10.12182/20240160504
引用本文: 段沛言, 刘艺, 林心怡, 等. 细胞外基质硬度通过AMPK调控干细胞线粒体的形态异质性[J]. 四川大学学报(医学版), 2024, 55(1): 47-52. DOI: 10.12182/20240160504
DUAN Peiyan, LIU Yi, LIN Xinyi, et al. Extracellular Matrix Stiffness Induces Mitochondrial Morphological Heterogeneity via AMPK Activation[J]. Journal of Sichuan University (Medical Sciences), 2024, 55(1): 47-52. DOI: 10.12182/20240160504
Citation: DUAN Peiyan, LIU Yi, LIN Xinyi, et al. Extracellular Matrix Stiffness Induces Mitochondrial Morphological Heterogeneity via AMPK Activation[J]. Journal of Sichuan University (Medical Sciences), 2024, 55(1): 47-52. DOI: 10.12182/20240160504

细胞外基质硬度通过AMPK调控干细胞线粒体的形态异质性

Extracellular Matrix Stiffness Induces Mitochondrial Morphological Heterogeneity via AMPK Activation

  • 摘要:
    目的 探讨人间充质干细胞(human mesenchymal stem cells, hMSCs)中线粒体形态对细胞外基质硬度的力学响应以及腺苷酸激活蛋白激酶(AMP-activated protein kinase, AMPK)对线粒体力学响应的调控作用。
    方法 首先,通过改变丙烯酰和甲叉双丙烯酰胺的单体浓度,制备杨氏模量为1 kPa(软)和20 kPa(硬)两种硬度的聚丙烯酰胺水凝胶;随后,将hMSCs培养在不同硬度水凝胶上,通过激光共聚焦显微镜和Western blot检测线粒体的形态变化和线粒体稳态相关蛋白AMPK的激活情况;最后,分别利用AMPK激活剂A-769662和抑制剂Compound C改变软硬基底上细胞AMPK的激活,观察线粒体的形态变化。
    结果 hMSCs中线粒体的形态随水凝胶硬度变化呈现异质性,在1 kPa软基质上,线粒体融合,有74%的线粒体呈现出致密的长纤维网络状结构,而在20 kPa硬基质上高达63.3%线粒体为疏松的短片段化或者点状形貌。Western blot结果显示,硬基质上p-AMPK/AMPK的比例是软基质上的1.6倍,免疫荧光染色结果显示在硬的基质p-AMPK的表达升高,并且呈现出核定位,证明随着细胞外基质硬度的提高,细胞内AMPK的激活程度也不断上升。当在软基质上添加AMPK激活剂A-769662后,线粒体形态由纤维网络状向片段化转变,纤维化程度由74%下降到9.5%,同时AMPK抑制剂Compound C可以促进硬基质上线粒体融合,降低点状线粒体占比。
    结论 细胞外基质硬度通过AMPK的激活调控hMSCs中线粒体的形态。硬基质会促进AMPK激活,导致线粒体分裂,形成大量片段化的短线粒体。这种基质硬度对线粒体形态的影响可以通过改变AMPK的磷酸化水平进行逆转。

     

    Abstract:
    Objective To investigate the mechanical responses of mitochondrial morphology to extracellular matrix stiffness in human mesenchymal stem cells (hMSCs) and the role of AMP-activated protein kinase (AMPK) in the regulation of mitochondrial mechanoresponses.
    Methods Two polyacrylamide (PAAm) hydrogels, a soft one with a Young's modulus of 1 kPa and a stiff one of 20 kPa, were prepared by changing the monomer concentrations of acrylamide and bis-acrylamide. Then, hMSCs were cultured on the soft and stiff PAAm hydrogels and changes in mitochondrial morphology were observed using a laser confocal microscope. Western blot was performed to determine the expression and activation of AMPK, a protein associated with mitochondrial homeostasis. Furthermore, the activation of AMPK was regulated on the soft and stiff matrixes by AMPK activator A-769662 and the inhibitor Compound C, respectively, to observe the morphological changes of mitochondria.
    Results The morphology of the mitochondria in hMSCs showed heterogeneity when there was a change in gel stiffness. On the 1 kPa soft matrix, 74% mitochondria exhibited a dense, elongated filamentous network structure, while on the 20 kPa stiff matrix, up to 63.3% mitochondria were fragmented or punctate and were sparsely distributed. Western blot results revealed that the phosphorylated AMPK (p-AMPK)/AMPK ratio on the stiff matrix was 1.6 times as high as that on the soft one. Immunofluorescence assay results revealed that the expression of p-AMPK was elevated on the hard matrix and showed nuclear localization, which indicated that the activation of intracellular AMPK increased continuously along with the increase in extracellular matrix stiffness. When the hMSCs on the soft matrix were treated with A-769662, an AMPK activator, the mitochondria transitioned from a filamentous network morphology to a fragmented morphology, with the ratio of filamentous network decreasing from 74% to 9.5%. Additionally, AMPK inhibition with Compound C promoted mitochondrial fusion on the stiff matrix and significantly reduced the generation of punctate mitochondria.
    Conclusion Extracellular matrix stiffness regulates mitochondrial morphology in hMSCs through the activation of AMPK. Stiff matrix promotes the AMPK activation, resulting in mitochondrial fission and the subsequent fragmentation of mitochondria. The impact of matrix stiffness on mitochondrial morphology can be reversed by altering the level of AMPK phosphorylation.

     

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