力生长因子促肌腱细胞迁移的新机制：细胞核力学特性变化及其分子基础

The nucleus, the largest and stiffest organelle, plays an important role in cell migration. Mechano-growth factor (MGF) is an alternative splice variant of the insulin like growth factor, and plays positive roles in repair and regeneration of a wide range of tissue types. In our previous studies, we demonstrated that MGF significantly promotes tenocyte migration and tendon healing. However, the change rule of the nuclear mechanics in MGF-promoted tenocyte migration and the involved molecular mechanisms remain unclear. In this project，using the methods of cell biology, molecular biology and biomechanics, we will detect the change rule of the nuclear mechanics in the process of MGF-promoted tenocyte migration, and study the effect of MGF on Lamin A/C expression and chromatin condensation, as well as their relationship with the nuclear mechanics. Furthermore, the role of FAK-ERK1/2 signaling pathway in mediating MGF-affected nuclear mechanics will be also explored. This study aims to disclose the molecular mechanisms of MGF-affected tenocyte nuclear mechanics and its relations with tenocyte migration. The results from this study will not only contribute to understanding the molecular mechanisms in MGF-promoted tenocyte migration from the point of view of nuclear mechanics, but also provide theoretical reference and experimental basis for application of MGF or other growth factors in tendon repair in clinic.

细胞核是真核细胞最大、最硬的细胞器，在细胞迁移过程中起重要调节作用。力生长因子（mechano-growth factor，MGF）是胰岛素样生长因子1基因选择剪接产生的变异体，在多种组织的损伤修复和再生中起重要作用。我们前期研究发现，MGF可以促进大鼠肌腱细胞迁移和损伤肌腱修复，但其中细胞核力学特性的变化规律及分子机理还不清楚。本项目整合生物力学、细胞生物学、分子生物学等技术，考察MGF促肌腱细胞迁移中细胞核力学特性的变化规律，探讨MGF作用下Lamin A/C表达和染色质浓缩的变化及其与细胞核力学特性的关系，并进一步研究FAK-ERK1/2信号途径在介导MGF影响肌腱细胞核力学特性中的作用，揭示细胞核力学特性变化的分子机理及其与细胞迁移的关系。该研究既有助于从细胞核力学角度揭示MGF促肌腱细胞迁移的新机制，也可为临床上应用MGF等生长因子进行损伤肌腱的治疗提供实验依据和理论指导。

细胞核是真核生物最大和最硬的细胞器，在细胞运动中起重要调节作用。力生长因子（mechano-growth factor，MGF）是胰岛素样生长因子1基因选择剪接产生的变异体，在多种组织的损伤修复和再生中起重要作用。我们前期研究发现，MGF可以促进大鼠肌腱细胞迁移和损伤肌腱修复，但其中细胞核力学特性的变化规律及分子机理还不清楚。本项目整合生物力学、细胞生物学、分子生物学等技术，考察了MGF促肌腱细胞迁移中细胞核力学特性的变化规律，检测了MGF作用下Lamin A/C表达和染色质浓缩的变化及其与细胞核力学特性的关系，并进一步研究了FAK-ERK1/2信号途径在介导MGF影响肌腱细胞核力学特性中的作用。研究结果发现，MGF通过FAK-ERK1/2信号通路增加肌腱细胞核的杨氏模量，使细胞核硬度增加。MGF对细胞核骨架蛋白Lamin A/C的表达没有明显影响，但可以促进染色质浓缩。抑制FAK或ERK1/2激活后，MGF促进的染色质浓缩受到明显抑制。此外，MGF促进肌腱细胞DNA甲基化，DNA甲基化抑制剂（methylthioadenosine，MTA）作用后，MGF促进的染色质浓缩、细胞核硬度及细胞迁移受到明显抑制。FAK和ERK1/2的抑制剂亦阻断MGF促进的DNA甲基化。上述结果表明，MGF通过FAK-ERK1/2信号通路促进染色质浓缩，增加细胞核硬度，从而提高肌腱细胞迁移能力。这些研究结果揭示了细胞核力学特性变化的分子机理及其与细胞迁移的关系，有助于从细胞核力学角度认识MGF促肌腱细胞迁移的新机制，为临床上应用MGF等生长因子进行损伤肌腱的治疗提供实验依据和理论指导。