LBPO.BCS02 · 生物信息与计算 · Late-Breaking
缺氧驱动的磷脂酰丝氨酸重塑促进头颈部鳞状细胞癌中ADAM17的构象可塑性
Hypoxia-driven phosphatidylserine remodeling promotes conformational plasticity of ADAM17 in head and neck squamous cell carcinoma
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摘要 Abstract
中文摘要
引言。解整合素金属蛋白酶17（ADAM17）通过对生长因子、细胞因子和黏附分子的脱落作用，是癌症进展的关键调控因子。在头颈部鳞状细胞癌（HNSCC）中，侵袭性疾病与缺氧肿瘤区域密切相关，后者驱动适应性信号传导、细胞外通讯和治疗耐药。在我们此前的工作中，我们证明缺氧增强了HNSCC细胞释放小细胞外囊泡（sEVs），且ADAM17被这些囊泡主动携带。值得注意的是，缺氧条件下产生的sEVs与常氧sEVs相比表现出更高的ADAM17活性，这一效应被磷脂酰丝氨酸（PS）抗体显著减弱。基于这些观察，我们假设ADAM17呈现出具有不同活性水平的不同构象状态，且PS的结合会触发向更活跃状态的转变。
方法。为研究脂质介导的ADAM17调控，我们进行了分子动力学模拟和轨迹分析（GROMACS、PACKMOL、CHARMM36、CGenFF），使用基于PS组成构建的膜模型（20nm²），该PS组成由缺氧和常氧HNSCC细胞系（PCI-30）来源sEVs的脂质组学分析提供依据。质谱脂质组学分析揭示了不同条件之间在酰基链长度和饱和度上存在差异的独特PS种类。基于这些数据，我们构建了反映实验观察到的PS组成的膜系统。将ADAM17的结构模型（PDB 8SNM）嵌入这些膜中，并进行了时间尺度模拟（5 ns），以评估缺氧和常氧模拟条件下的脂质-蛋白相互作用、PS结合动力学和ADAM17的构象响应，生成自由能景观和亚稳态之间的转变速率。
结果。分子动力学模拟揭示，ADAM17在反映缺氧与常氧肿瘤条件的膜中采样出不同的构象系综，这由sEV脂质组学所鉴定的磷脂酰丝氨酸（PS）酰基链长度和饱和度差异所驱动。这些缺氧PS组成稳定了类开放的ADAM17构象，其特征为相对于常氧膜，膜近端结构域倾斜角增大（≈92°，平均Δ = 3.1°）、主链RMSD波动增大（ΔRMSD ≈ −0.79 Å），以及膜表面与催化结构域之间的间距增大（Δ距离 ≈ +25 Å）。自由能分析揭示，在缺氧PS条件下，群体向较低能量的开放状态移动（ΔG ≈ −1.0 kJ/mol），提供了将肿瘤缺氧驱动的脂质重塑与ADAM17活性增强相联系的分子机制。
结论。我们的结果提供了一个分子框架，将缺氧驱动的sEV膜脂质重塑与HNSCC中ADAM17活性增强相联系。通过整合脂质组学指导的膜建模与分子模拟，本研究强调磷脂酰丝氨酸是侵袭性肿瘤中ADAM17功能的关键调控因子。靶向PS依赖性的脂质-蛋白相互作用可能代表一种在缺氧癌症微环境中调节ADAM17介导信号传导的新策略。
查看英文原文 English abstract
Introduction. A Disintegrin and Metalloprotease 17 (ADAM17) is a critical regulator of cancer progression through the shedding of growth factors, cytokines, and adhesion molecules. In head and neck squamous cell carcinoma (HNSCC), aggressive disease is closely associated with hypoxic tumor regions that drive adaptive signaling, extracellular communication, and therapy resistance. In our previous work, we demonstrated that hypoxia enhances the release of small extracellular vesicles (sEVs) from HNSCC cells and that ADAM17 is actively carried by these vesicles. Notably, sEVs derived under hypoxic conditions exhibited higher ADAM17 activity compared with normoxic sEVs, an effect significantly attenuated by phosphatidylserine (PS) antibody. Due to these observations, we hypothesized that ADAM17 assumes different conformational states with different levels of activity, and that PS engagement triggers a change towards more active states.
Methods. To investigate lipid-mediated regulation of ADAM17, we performed molecular dynamics simulations and trajectory analysis (GROMACS, PACKMOL, CHARMM36, CGenFF) using membrane models (20nm 2 ) bulid on PS composition informed by lipidomics analysis of sEVs derived from hypoxic and normoxic HNSCC cell line (PCI-30). Mass spectrometry lipidomic profiling revealed distinct PS species differing in acyl chain length and saturation between conditions. Based on these data, we constructed membrane systems reflecting the experimentally observed PS compositions. A structural model of ADAM17 (PDB 8SNM) was embedded in these membranes, and timescale simulations (5 ns) were conducted to assess lipid-protein interactions, PS binding dynamics, and conformational responses of ADAM17 under hypoxia- and normoxia-mimicking conditions, producing free energy landscapes and transition rates between metastable states.
Results. Molecular dynamics simulations revealed that ADAM17 samples distinct conformational ensembles in membranes reflecting hypoxic versus normoxic tumor conditions, driven by differences in phosphatidylserine (PS) acyl chain length and saturation identified by sEV lipidomics. These hypoxic PS compositions stabilized open-like ADAM17 conformations, characterized by increased membrane-proximal domain tilt angles (≈92°, mean Δ = 3.1°), increased backbone RMSD fluctuations (ΔRMSD ≈ −0.79 Å), and increased separation between the membrane surface and the catalytic domain (Δdistance ≈ +25 Å) relative to normoxic membranes. Free-energy analysis revealed a population shift toward lower-energy open states under hypoxic PS conditions (ΔG ≈ −1.0 kJ/mol), providing a molecular mechanism linking tumor hypoxia-driven lipid remodeling to enhanced ADAM17 activity.
Conclusion. Our results provide a molecular framework linking hypoxia-driven lipid remodeling of sEV membranes to enhanced ADAM17 activity in HNSCC. By integrating lipidomics-guided membrane modeling with molecular simulations, this study highlights phosphatidylserine as a key regulator of ADAM17 function in aggressive tumors. Targeting PS-dependent lipid-protein interactions may represent a novel strategy to modulate ADAM17-mediated signaling in hypoxic cancer microenvironments.
利益披露 Disclosure
J. Waters, None..
J. Wannebo, None..
A. Gluszko, None.