Department of Biochemistry, Medical University-Pleven, 5800 Pleven, Bulgaria.
Department of Experimental and Clinical Pharmacology, Medical University-Pleven, 5800 Pleven, Bulgaria.
Int J Mol Sci. 2022 Mar 11;23(6):3058. doi: 10.3390/ijms23063058.
This study describes the effect of collagen type I (Col I) oxidation on its physiological remodeling by adipose tissue-derived mesenchymal stem cells (ADMSCs), both mechanical and proteolytic, as an in vitro model for the acute oxidative stress that may occur in vivo upon distinct environmental changes. Morphologically, remodeling was interpreted as the mechanical rearrangement of adsorbed FITC-labelled Col I into a fibril-like pattern. This process was strongly abrogated in cells cultured on oxidized Col I albeit without visible changes in cell morphology. Proteolytic activity was quantified utilizing fluorescence de-quenching (FRET effect). The presence of ADMSCs caused a significant increase in native FITC-Col I fluorescence, which was almost absent in the oxidized samples. Parallel studies in a cell-free system confirmed the enzymatic de-quenching of native FITC-Col I by Clostridial collagenase with statistically significant inhibition occurring in the oxidized samples. Structural changes to the oxidized Col I were further studied by differential scanning calorimetry. In the oxidized samples, an additional endotherm with sustained enthalpy (∆H) was observed at 33.6 °C along with Col I's typical one at 40.5 °C. Collectively, these data support that the remodeling of Col I by ADMSCs is altered upon oxidation due to intrinsic changes to the protein's structure, which represents a novel mechanism for the control of stem cell behavior.
本研究描述了 I 型胶原蛋白(Col I)氧化对脂肪组织来源间充质干细胞(ADMSCs)机械重塑和蛋白水解重塑的影响,这是一种体外模型,用于模拟体内由于环境变化而发生的急性氧化应激。从形态学上看,重塑被解释为吸附的 FITC 标记的 Col I 在纤维样模式下的机械重排。尽管细胞形态没有明显变化,但在培养于氧化 Col I 上的细胞中,该过程被强烈阻断。利用荧光去猝灭(FRET 效应)来定量蛋白水解活性。ADMSCs 的存在导致天然 FITC-Col I 荧光显著增加,而在氧化样本中几乎不存在。在无细胞体系中的平行研究证实了梭菌胶原酶对天然 FITC-Col I 的酶促去猝灭作用,并且在氧化样本中存在统计学显著的抑制作用。通过差示扫描量热法进一步研究了氧化 Col I 的结构变化。在氧化样本中,在 33.6°C 处观察到另一个具有持续焓(∆H)的吸热峰,同时 Col I 的典型吸热峰在 40.5°C 处。综上所述,这些数据表明,ADMSCs 对 Col I 的重塑由于蛋白质结构的固有变化而在氧化后发生改变,这代表了控制干细胞行为的一种新机制。
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