Ningbo Institute of Innovation for Combined Medicine and Engineering, Lihuili Hospital Affiliated to Ningbo University, Ningbo University, Ningbo 315211, China.
School of Medicine, Ningbo University, Ningbo 315211, China.
J Chem Inf Model. 2024 Jun 10;64(11):4500-4510. doi: 10.1021/acs.jcim.4c00553. Epub 2024 May 14.
Human calcitonin (hCT) regulates calcium-phosphorus metabolism, but its amyloid aggregation disrupts physiological activity, increases thyroid carcinoma risk, and hampers its clinical use for bone-related diseases like osteoporosis and Paget's disease. Improving hCT with targeted modifications to mitigate amyloid formation while maintaining its function holds promise as a strategy. Understanding how each residue in hCT's amyloidogenic core affects its structure and aggregation dynamics is crucial for designing effective analogues. Mutants F16L-hCT and F19L-hCT, where Phe residues in the core are replaced with Leu as in nonamyloidogenic salmon calcitonin, showed different aggregation kinetics. However, the molecular effects of these substitutions in hCT are still unclear. Here, we systematically investigated the folding and self-assembly conformational dynamics of hCT, F16L-hCT, and F19L-hCT through multiple long-time scale independent atomistic discrete molecular dynamics (DMD) simulations. Our results indicated that the hCT monomer primarily assumed unstructured conformations with dynamic helices around residues 4-12 and 14-21. During self-assembly, the amyloidogenic core of hCT converted from dynamic helices to β-sheets. However, substituting F16L did not induce significant conformational changes, as F16L-hCT exhibited characteristics similar to those of wild-type hCT in both monomeric and oligomeric states. In contrast, F19L-hCT exhibited substantially more helices and fewer β-sheets than did hCT, irrespective of their monomers or oligomers. The substitution of F19L significantly enhanced the stability of the helical conformation for hCT, thereby suppressing the helix-to-β-sheet conformational conversion. Overall, our findings elucidate the molecular mechanisms underlying hCT aggregation and the effects of F16L and F19L substitutions on the conformational dynamics of hCT, highlighting the critical role of F19 as an important target in the design of amyloid-resistant hCT analogs for future clinical applications.
人降钙素（hCT）调节钙磷代谢，但它的淀粉样聚集会破坏生理活性，增加甲状腺癌风险，并阻碍其在骨质疏松症和 Pagets 病等与骨骼相关疾病中的临床应用。通过靶向修饰 hCT 以减轻淀粉样形成同时保持其功能具有很大的应用前景。了解 hCT 的淀粉样核心中的每个残基如何影响其结构和聚集动力学对于设计有效的类似物至关重要。突变体 F16L-hCT 和 F19L-hCT 中，核心中的苯丙氨酸残基被非淀粉样生成的鲑鱼降钙素中的亮氨酸取代，表现出不同的聚集动力学。然而，这些取代在 hCT 中的分子效应仍不清楚。在这里，我们通过多个长时间尺度独立原子离散分子动力学（DMD）模拟系统地研究了 hCT、F16L-hCT 和 F19L-hCT 的折叠和自组装构象动力学。我们的结果表明，hCT 单体主要呈现无规卷曲构象，其 4-12 位和 14-21 位残基周围有动态螺旋。在自组装过程中，hCT 的淀粉样核心从动态螺旋转变为β-折叠。然而，取代 F16L 并没有引起明显的构象变化，因为 F16L-hCT 在单体和寡聚态下都表现出与野生型 hCT 相似的特征。相比之下，F19L-hCT 表现出比 hCT 更多的螺旋和更少的β-折叠，无论单体还是寡聚体都是如此。F19L 的取代显著增强了 hCT 螺旋构象的稳定性，从而抑制了螺旋到β-折叠的构象转换。总的来说，我们的研究结果阐明了 hCT 聚集的分子机制以及 F16L 和 F19L 取代对 hCT 构象动力学的影响，突出了 F19 作为设计抗淀粉样形成 hCT 类似物的重要靶标在未来临床应用中的关键作用。
