产生胰岛素的β细胞的死亡是2型糖尿病发病的关键步骤。淀粉样肽胰岛淀粉样多肽(IAPP,也称为胰淀素)已被证明会破坏β细胞膜,导致β细胞死亡。尽管有强有力的证据将IAPP与β细胞膜完整性的破坏和细胞死亡联系起来,IAPP毒性的机制知之甚少。特别是,IAPP对双层结构的影响在很大程度上没有被表征。在这项研究中,我们已经通过DSC和固态NMR光谱的组合确定了淀粉样蛋白和有毒的hIAPP(1-37)肽以及无毒和非淀粉样蛋白的rIAPP(1-37)肽对膜的影响。我们还表征了毒性但主要是非淀粉样蛋白的rIAPP(1-19)和hIAPP(1-19)片段。DSC显示,该肽的淀粉样蛋白(hIAPP(1-37))和大部分非淀粉样蛋白样蛋白(hIAPP(1-19)和rIAPP(1-19))毒性版本强烈促进脂质双层中负曲率的形成,而无毒的全长大鼠IAPP(1-37)肽则没有。该结果通过固态NMR光谱得到证实,该光谱表明,在由高曲率和低曲率区域组成的双胶束中,无毒的rIAPP(1-37)与低曲率区域结合,而有毒的rIAPP(1-19)与高曲率区域结合。同样,固态核磁共振波谱表明,有毒的rIAPP(1-19)肽显著破坏脂质双层结构,而无毒的rIAPP(1-37)没有显着影响。这些结果表明IAPP可以通过诱导过度的膜曲率来诱导孔的形成,并且可以用于指导可以防止IAPP的细胞毒性的化合物的设计。这种机制对于理解其他淀粉样蛋白的毒性可能很重要。我们的固态NMR结果还证明了使用双胶束测量生物分子对膜的负或正弯曲区域的亲和力的可能性,我们认为这将有助于与细胞膜相关的各种生化和生物物理研究。
The death of insulin-producing beta-cells is a key step in the pathogenesis of type 2 diabetes. The amyloidogenic peptide Islet Amyloid Polypeptide (IAPP, also known as amylin) has been shown to disrupt beta-cell membranes leading to beta-cell death. Despite the strong evidence linking IAPP to the destruction of beta-cell membrane integrity and cell death, the mechanism of IAPP toxicity is poorly understood. In particular, the effect of IAPP on the bilayer structure has largely been uncharacterized. In this study, we have determined the effect of the amyloidogenic and toxic hIAPP(1-37) peptide and the nontoxic and nonamyloidogenic rIAPP(1-37) peptide on membranes by a combination of DSC and solid-state NMR spectroscopy. We also characterized the toxic but largely nonamyloidogenic rIAPP(1-19) and hIAPP(1-19) fragments. DSC shows that both amyloidogenic (hIAPP(1-37)) and largely nonamyloidogenic (hIAPP(1-19) and rIAPP(1-19)) toxic versions of the peptide strongly favor the formation of negative curvature in lipid bilayers, while the nontoxic full-length rat IAPP(1-37) peptide does not. This result was confirmed by solid-state NMR spectroscopy which shows that in bicelles composed of regions of high curvature and low curvature, nontoxic rIAPP(1-37) binds to the regions of low curvature while toxic rIAPP(1-19) binds to regions of high curvature. Similarly, solid-state NMR spectroscopy shows that the toxic rIAPP(1-19) peptide significantly disrupts the lipid bilayer structure, whereas the nontoxic rIAPP(1-37) does not have a significant effect. These results indicate IAPP may induce the formation of pores by the induction of excess membrane curvature and can be used to guide the design of compounds that can prevent the cell-toxicity of IAPP. This mechanism may be important to understand the toxicity of other amyloidogenic proteins. Our solid-state NMR results also demonstrate the possibility of using bicelles to measure the affinity of biomolecules for negatively or positively curved regions of the membrane, which we believe will be useful in a variety of biochemical and biophysical investigations related to the cell membrane.