Abstract：
The misfolding and aggregation of human islet amyloid polypeptide (hIAPP), also known as amylin, have been implicated in the pathogenesis of type 2 diabetes (T2D). Heat shock proteins, specifically, heat shock cognate 70 (Hsc70), are molecular chaperones that protect against hIAPP misfolding and inhibits its aggregation. Nevertheless, there is an incomplete understanding of the mechanistic interactions between Hsc70 domains and hIAPP, thus limiting their potential therapeutic role in diabetes. This study investigates the inhibitory capacities of different Hsc70 variants, aiming to identify the structural determinants that strike a balance between efficacy and cytotoxicity. Our experimental findings demonstrate that the ATPase activity of Hsc70 is not a pivotal factor for inhibiting hIAPP misfolding. We underscore the significance of the C-terminal substrate-binding domain of Hsc70 in inhibiting hIAPP aggregation, emphasizing that the removal of the lid subdomain diminishes the inhibitory effect of Hsc70. Additionally, we employed atomistic discrete molecular dynamics simulations to gain deeper insights into the interaction between Hsc70 variants and hIAPP. Integrating both experimental and computational findings, we propose a mechanism by which Hsc70\'s interaction with hIAPP monomers disrupts protein-protein connections, primarily by shielding the β-sheet edges of the Hsc70-β-sandwich. The distinctive conformational dynamics of the alpha helices of Hsc70 potentially enhance hIAPP binding by obstructing the exposed edges of the β-sandwich, particularly at the β5-β8 region along the alpha helix interface. This, in turn, inhibits fibril growth, and similar results were observed following hIAPP dimerization. Overall, this study elucidates the structural intricacies of Hsc70 crucial for impeding hIAPP aggregation, improving our understanding of the potential anti-aggregative properties of molecular chaperones in diabetes treatment.
摘要：
人胰岛淀粉样多肽（hIAPP）的错误折叠和聚集，也被称为胰淀素，与2型糖尿病（T2D）的发病机制有关。热休克蛋白,具体来说,热休克同源70（HSC70），是分子伴侣，可防止hIAPP错误折叠并抑制其聚集。然而，对HSC70域和HIAPP之间的机械相互作用有不完全的理解，从而限制了它们在糖尿病中的潜在治疗作用。本研究调查了不同Hsc70变体的抑制能力，旨在确定在功效和细胞毒性之间取得平衡的结构决定因素。我们的实验发现表明，Hsc70的ATPase活性不是抑制hIAPP错误折叠的关键因素。我们强调了Hsc70的C端底物结合域在抑制hIAPP聚集中的重要性，强调盖子亚结构域的去除会降低Hsc70的抑制作用。此外,我们使用原子离散分子动力学模拟来更深入地了解Hsc70变体和hIAPP之间的相互作用。整合实验和计算发现，我们提出了HSC70与hIAPP单体相互作用破坏蛋白质-蛋白质连接的机制，主要通过屏蔽Hsc70-β-三明治的β-折叠边缘。Hsc70的α螺旋的独特构象动力学可能通过阻碍β-三明治的暴露边缘来增强hIAPP结合，特别是在沿α螺旋界面的β5-β8区域。这个,反过来,抑制原纤维生长，在hIAPP二聚化后观察到类似的结果。总的来说,这项研究阐明了HSC70对阻碍HIAPP聚集至关重要的结构复杂性，提高我们对分子伴侣在糖尿病治疗中的潜在抗聚集特性的理解。
