Cyclic mechanical stretching of human patellar tendon fibroblasts: activation of JNK and modulation of apoptosis
Cyclic mechanical stretching of human patellar tendon fibroblasts: activation of JNK and modulation of apoptosis
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DOI：
10.1007/s00167-002-0322-y
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发表时间：
2003-03-01
影响因子：
3.8
通讯作者：
Bosch, U
中科院分区：
文献类型：
--
作者：
Skutek, M;van Griensven, M;Bosch, U
肌腱、韧带和骨损伤后的加速康复被广泛接受，以避免固定的不良影响。然而，渐进式康复也可能导致过度的软组织炎症反应，并经常导致结构和功能问题，如过度瘢痕。在分子/细胞水平上的等效部分是增殖和凋亡之间敏感稳态的调节。然而，很少有人关注肌腱的这方面发病机制。本研究研究了人肌腱成纤维细胞在细胞凋亡和Jun n -末端激酶（JNK）激活对循环机械拉伸的预期改变方面的反应谱。6例患者的人肌腱成纤维细胞以1 Hz拉伸15或60 min，伸长率为5%。western blot检测应激活化蛋白激酶(SAPK)/JNK的活化情况。用annexin-V染色和流式细胞术检测拉伸细胞和对照组的凋亡细胞。此外，通过连接介导（LM）聚合酶链反应（PCR）测定DNA阶梯。拉伸15和60分钟后，SAPK/JNK的激活在60分钟后达到最大值。然而，较长拉伸时间后JNK的激活比较短拉伸时间（15 min）后减少50%。短时间拉伸后细胞凋亡率相应升高，而长时间拉伸后细胞凋亡率不升高。这可能是由于细胞保护机制使活化的jnk失活所致。研究结果表明，机械拉伸直接激活细胞内信号通路，进而诱导细胞凋亡。拉伸时间越长，细胞凋亡率越低，这是由于细胞对应力的耐受性提高所致。这可能是由热休克蛋白介导的JNK活化抑制引起的。这一新的观察结果是一个重要的问题，正如定义的机械拉伸，取决于其持续时间，调节细胞凋亡，从而影响肌腱重塑。
Accelerated rehabilitation after tendon, ligament and bone injuries is widely accepted to avoid adverse effects of immobilization. However, progressive rehabilitation may also lead to an excessive inflammatory soft tissue response and often leads to structural and functional problems such as excessive scarring. The equivalent at the molecular/cellular level is in part the regulation of the sensitive homeostasis between proliferation and apoptosis. However, little attention has been paid to this aspect of tendon pathogenesis. This study investigated the response profile of human tendon fibroblasts in terms of apoptosis and anticipated alteration of Jun N-terminal kinase (JNK) activation to cyclic mechanical stretching. Human tendon fibroblasts of six patients were stretched for 15 or 60 min with 1 Hz and an elongation of 5%. Activation of stress-activated protein kinase (SAPK)/JNK was measured by western blot analysis. Apoptotic cells were determined in the stretched cells and in controls by annexin-V staining and detection by flow cytometry. Additionally DNA laddering was determined by ligation-mediated (LM) polymerase chain reaction (PCR). Application of 15 and 60 min stretch increased activation of SAPK/JNK at a maximum after 60 min. However, JNK activation after the longer stretch period 50% less than after the shorter stretch period (15 min). The apoptosis rate was correspondingly increased after short stretch application but not after longer stretch. This might be caused by an inactivation of the activated JNKs by cell protection mechanisms. The findings suggest that mechanical stretching directly activates intracellular signaling pathways, which in turn induce apoptosis. The longer stretch period resulted in a decreased apoptotic rate due to development of stress tolerance. This might be caused by heat-shock protein mediated suppression of JNK activation. This novel observation is an important issue, as defined mechanical stretching, depending on its duration, modulates apoptosis and thus affects tendon remodeling.