Sørensen Charlotte S, Runager Kasper, Scavenius Carsten, Jensen Morten M, Nielsen Nadia S, Christiansen Gunna, Petersen Steen V, Karring Henrik, Sanggaard Kristian W, Enghild Jan J
⊥Department of Biomedicine, Aarhus University, Wilhelm Meyers Allé 4, DK-8000 Aarhus C, Denmark.
∥Department of Chemical Engineering, Biotechnology and Environmental Technology, University of Southern Denmark, Niels Bohrs Allé 1, DK-5230 Odense M, Denmark.
Biochemistry. 2015 May 19;54(19):2943-56. doi: 10.1021/acs.biochem.5b00292. Epub 2015 May 6.
Mutations in the transforming growth factor beta-induced (TGFBI) gene result in a group of hereditary diseases of the cornea that are collectively known as TGFBI corneal dystrophies. These mutations translate into amino acid substitutions mainly within the fourth fasciclin 1 domain (FAS1-4) of the transforming growth factor beta-induced protein (TGFBIp) and cause either amyloid or nonamyloid protein aggregates in the anterior and central parts of the cornea, depending on the mutation. The A546T substitution in TGFBIp causes lattice corneal dystrophy (LCD), which manifests as amyloid-type aggregates in the corneal stroma. We previously showed that the A546T substitution renders TGFBIp and the FAS1-4 domain thermodynamically less stable compared with the wild-type (WT) protein, and the mutant FAS1-4 is prone to amyloid formation in vitro. In the present study, we identified the core of A546T FAS1-4 amyloid fibrils. Significantly, we identified the Y571-R588 region of TGFBIp, which we previously found to be enriched in amyloid deposits in LCD patients. We further found that the Y571-R588 peptide seeded fibrillation of A546T FAS1-4, and, more importantly, we demonstrated that native TGFBIp aggregates in the presence of fibrils formed by the core peptide. Collectively, these data suggest an involvement of the Y571-R588 peptide in LCD pathophysiology.
转化生长因子β诱导（TGFBI）基因突变会导致一组角膜遗传性疾病，统称为TGFBI角膜营养不良。这些突变主要导致转化生长因子β诱导蛋白（TGFBIp）的第四纤连蛋白1结构域（FAS1-4）内的氨基酸替换，并根据突变情况在角膜前部和中央部分导致淀粉样或非淀粉样蛋白聚集体。TGFBIp中的A546T替换会导致格子状角膜营养不良（LCD），表现为角膜基质中的淀粉样聚集体。我们之前表明，与野生型（WT）蛋白相比，A546T替换使TGFBIp和FAS1-4结构域在热力学上更不稳定，并且突变的FAS1-4在体外易于形成淀粉样蛋白。在本研究中，我们确定了A546T FAS1-4淀粉样纤维的核心。重要的是，我们确定了TGFBIp的Y571-R588区域，我们之前发现该区域在LCD患者的淀粉样沉积物中富集。我们进一步发现Y571-R588肽引发了A546T FAS1-4的纤维化，更重要的是，我们证明了天然TGFBIp在由核心肽形成的纤维存在下会聚集。总体而言，这些数据表明Y571-R588肽参与了LCD的病理生理学过程。
