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Title:: Fibronectin adhesion strength regulates PDGF-induced Fyn activity in rat airway smooth muscle cells

Author(s):: YAO Hui; DENG Linhong; OUYANG Mingxing; Institute of Biomedical Engineering and Health Sciences, Changzhou University,Changzhou 213164,China

Keywords:: Airway smooth muscle cells; Fyn kinase; Cell adhesion strength; Fluorescence resonance energy transfer; Platelet-derived growth factor

摘要:: 气道平滑肌（airway smooth muscle，ASM）有收缩和舒张的功能，而哮喘的气道高反应中，ASM保持高收缩状态的表型，引起支气管痉挛和呼吸功能受损，但其生物力学机制尚不清楚。Fyn作为非受体酪氨酸激酶Src家族成员，在多个生理、病理过程中起作用。炎症因子如血小板生长因子（platelet-derived growth factor, PDGF）能刺激ASM细胞的增殖和诱导收缩延长效应，利用荧光共振能量转移技术（fluorescence resonance energy transfer，FRET），本研究发现PDGF能快速高效地激活ASM细胞中Fyn的活性(约110% FRET变化)。通过改变表面Fibronectin的包被浓度(1.25~40 μg/mL)调节细胞-基质黏附强度，证实PDGF诱导Fyn的激活水平与黏附强度有正相关性，显示力学微环境影响ASM细胞中化学信号的可能性。研究中，减弱细胞内部收缩力对Fyn激活水平无明显影响。此初步性工作对理解哮喘条件下力学微环境改变对ASM细胞内的生化信号影响提供了一些思路。

Abstract:: Airway smooth muscle (ASM) in respiratory system has regular contraction and relaxation， whereas during airway hyper-responsiveness under asthma condition, ASM maintains contraction force to prevent air flow through bronchial tubes. Fyn as one member of non-receptor tyrosine kinase Src family is involved into multiple physiological and pathological processes, and reportedly fibronectin-coated substrate rigidity-regulated biomechanical response. Here we tried to look at Fyn activity by fluorescence resonance energy transfer (FRET) technology in cultured rat ASM cells. Platelets-derived growth factor (PDGF), which was reported able to cause ASM proliferation and hypercontractivity, induced a rapid and efficient Fyn activation measured by about 110% FRET change in ASM cells. By coating the cover slips with gradient fibronectin concentrations ranging from 1.25 to 40 μg/mL, we found a positive correlation between PDGF-induced Fyn activity and cell-fibronectin adhesion strength, indicating a possible influence of mechanical microenvironment on biochemical signaling in ASM cells. Reduction of intracellular contraction force didn’t obviously change PDGF-induced Fyn activity. This work may help provide some clue to the possible impact on biochemical signals in ASM cells from changed mechanical microenvironment under asthma condition.