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首页> 外文期刊>Proceedings of the National Academy of Sciences of the United States of America >Fibronectin forms the most extensible biological fibers displaying switchable force-exposed cryptic binding sites
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Fibronectin forms the most extensible biological fibers displaying switchable force-exposed cryptic binding sites

机译：纤连蛋白形成最可延展的生物纤维，显示出可切换的力暴露的神秘结合位点

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摘要

Rather than maximizing toughness, as needed for silk and muscle titin fibers to withstand external impact, the much softer extracellular matrix fibers made from fibronectin (Fn) can be stretched by cell generated forces and display extraordinary extensibility. We show that Fn fibers can be extended more than 8-fold (>700% strain) before 50% of the fibers break. The Young's modulus of single fibers, given by the highly nonlinear slope of the stress-strain curve, changes orders of magnitude, up to MPa. Although many other materials plastically deform before they rupture, evidence is provided that the reversible breakage of force-bearing backbone hydrogen bonds enables the large strain. When tension is released, the nano-sized Fn domains first contract in the crowded environment of fibers within seconds into random coil conformations (molten globule states), before the force-bearing hydrogen bond networks that stabilize the domain's secondary structures are reestablished within minutes (double exponential). The exposure of cryptic binding sites on Fn type III modules increases steeply upon stretching. Thus fiber extension steadily up-regulates fiber rigidity and cryptic epitope exposure, both of which are known to differentially alter cell behavior. Finally, since stress-strain relationships cannot directly be measured in native extracellular matrix (ECM), the stress-strain curves were correlated with stretch-induced alterations of intramolecular fluorescence resonance energy transfer (FRET) obtained from trace amounts of Fn probes (mechanical strain sensors) that can be incorporated into native ECM. Physiological implications of the extraordinary extensibility of Fn fibers and contraction kinetics are discussed.
机译：由纤连蛋白（Fn）制成的柔软得多的细胞外基质纤维可以通过细胞产生的力进行拉伸，并显示出非凡的可扩展性，而不是使丝绸和肌肉纤维素纤维需要承受外部冲击所需的最大韧性。我们表明，在50％的纤维断裂之前，Fn纤维可以延伸8倍以上（> 700％应变）。单纤维的杨氏模量由应力-应变曲线的高度非线性斜率给出，变化幅度高达MPa。尽管许多其他材料在破裂之前会发生塑性变形，但有证据表明，受力主链氢键的可逆断裂使得产生大应变。释放张力后，纳米Fn域会在数秒内首先在拥挤的纤维环境中收缩成随机的线圈构型（熔融的球状态），然后在几分钟内重新建立稳定该域二级结构的受力氢键网络（双指数）。 Fn III型模块上的隐秘结合位点的暴露在拉伸时急剧增加。因此，纤维延伸稳定地上调了纤维的刚度和隐秘的抗原决定基暴露，这两种已知差异地改变细胞行为。最后，由于不能直接在天然细胞外基质（ECM）中测量应力-应变关系，因此应力-应变曲线与拉伸诱导的从痕量Fn探针获得的分子内荧光共振能量转移（FRET）的变化相关（机械应变）传感器），可以将其合并到本地ECM中。 Fn纤维具有非凡的可扩展性和收缩动力学的生理意义进行了讨论。

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  • 作者

    Enrico Klotzsch; Michael L. Smith; Kristopher E. Kubow; Simon Muntwyler; William C. Little; Felix Beyeler; Delphine Gourdon; Bradley J. Nelson; Viola Vogel;

  • 作者单位

    Department of Materials, Eidgenoessische Technische Hochschule (ETH) Zurich, CH-8093 Zurich, Switzerland;

    Department of Materials, Eidgenoessische Technische Hochschule (ETH) Zurich, CH-8093 Zurich, Switzerland Department of Biomedical Engineering, Boston University, Boston,MA 02215;

    Department of Materials, Eidgenoessische Technische Hochschule (ETH) Zurich, CH-8093 Zurich, Switzerland Department of Cell Biology, University of Virginia, Charlottesville, VA 22908;

    lnstitute of Robotics and Intelligent Systems, Eidgenoessische Technische Hochschule (ETH) Zurich, CH-8093 Zurich, Switzerland Femtotools GmbH, c/o ETH Zurich-IRIS, CLA H19, Tannenstrasse 3, CH-8092 Zurich, Switzerland;

    Department of Materials, Eidgenoessische Technische Hochschule (ETH) Zurich, CH-8093 Zurich, Switzerland;

    lnstitute of Robotics and Intelligent Systems, Eidgenoessische Technische Hochschule (ETH) Zurich, CH-8093 Zurich, Switzerland Femtotools GmbH, c/o ETH Zurich-IRIS, CLA H19, Tannenstrasse 3, CH-8092 Zurich, Switzerland;

    Department of Materials, Eidgenoessische Technische Hochschule (ETH) Zurich, CH-8093 Zurich, Switzerland Department of Materials Science and Engineering, Cornell University,Ithaca, NY 14853;

    lnstitute of Robotics and Intelligent Systems, Eidgenoessische Technische Hochschule (ETH) Zurich, CH-8093 Zurich, Switzerland;

    Department of Materials, Eidgenoessische Technische Hochschule (ETH) Zurich, CH-8093 Zurich, Switzerland;

  • 收录信息 美国《科学引文索引》(SCI);美国《生物学医学文摘》(MEDLINE);美国《化学文摘》(CA);
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

    fibrillogenesis; matrix biology; mechanotransduction; multimodular proteins; supramolecular assembly;

    机译：原纤维形成;基质生物学机械转导;多模块蛋白超分子组装;

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