Iwaki Takayuki, Nagahashi Kotomi, Takano Katsuhiro, Suzuki-Inoue Katsue, Kanayama Naohiro, Umemura Kazuo, Urano Tetsumei
Dr. Takayuki Iwaki, Department of Pharmacology, Hamamatsu University School of Medicine, 1-20-1 Handayama, Higashiku, Hamamatsu Shizuoka, Japan, E-mail:
Thromb Haemost. 2017 May 3;117(5):860-869. doi: 10.1160/TH16-07-0572. Epub 2017 Feb 23.
Serpinopathy is characterised as abnormal accumulation of serine protease inhibitors (SERPINs) in cells and results in clinical symptoms owing to lack of SERPIN function or excessive accumulation of abnormal SERPIN. We recently identified a patient with functional deficiency of plasminogen activator inhibitor-1 (PAI-1), a member of the SERPIN superfamily. The patient exhibited life-threatening bleeding tendencies, which have also been observed in patients with a complete deficiency in PAI-1. Sequence analysis revealed a homozygous single-nucleotide substitution from guanine to cytosine at exon 9, which changed amino acid residue 397 from glycine to arginine (c.1189G>C; p.Gly397Arg). This glycine was located in strand 5B and was well conserved in other serpins. The mutant PAI-1 was polymerised in the cells, interfering with PAI-1 secretion. The corresponding mutations in SERPINC1 (anti-thrombin III) at position 456 (Gly456Arg) and SERPINI1 (neuroserpin) at position 392 (Gly392Glu) caused an anti-thrombin deficiency and severe dementia due to intracellular retention of the polymers. Glycine is the smallest amino acid, and these mutated amino acids were larger and charged. To determine which factors were important, further mutagenesis of PAI-1 was performed. Although the G397A, C, I, L, S, T, and V were secreted, the G397D, E, F, H, K, M, N, P, Q, W, and Y were not secreted. The results revealed that the size was likely triggered by the polymerisation of SEPRINs at this position. Structural analyses of this mutated PAI-1 would be useful to develop a novel PAI-1 inhibitor, which may be applicable in the context of several pathological states.
丝氨酸蛋白酶抑制剂病的特征是细胞内丝氨酸蛋白酶抑制剂（SERPINs）异常蓄积，并因SERPIN功能缺乏或异常SERPIN过度蓄积而导致临床症状。我们最近鉴定出一名纤溶酶原激活物抑制剂-1（PAI-1）功能缺陷的患者，PAI-1是SERPIN超家族的成员。该患者表现出危及生命的出血倾向，这在PAI-1完全缺乏的患者中也有观察到。序列分析显示外显子9处有一个从鸟嘌呤到胞嘧啶的纯合单核苷酸替换，该替换将氨基酸残基397从甘氨酸变为精氨酸（c.1189G>C；p.Gly397Arg）。这个甘氨酸位于5B链，在其他丝氨酸蛋白酶抑制剂中高度保守。突变的PAI-1在细胞内聚合，干扰了PAI-1的分泌。SERPINC1（抗凝血酶III）第456位（Gly456Arg）和SERPINI1（神经丝氨酸蛋白酶抑制剂）第392位（Gly392Glu）的相应突变分别导致抗凝血酶缺乏和由于聚合物在细胞内潴留而引起的严重痴呆。甘氨酸是最小的氨基酸，而这些突变的氨基酸更大且带电荷。为了确定哪些因素很重要，我们对PAI-1进行了进一步的诱变。虽然G397A、C、I、L、S、T和V能够分泌，但G397D、E、F、H、K、M、N、P、Q、W和Y则不能分泌。结果表明，这种大小差异可能是由该位置的丝氨酸蛋白酶抑制剂聚合引发的。对这种突变的PAI-1进行结构分析将有助于开发一种新型PAI-1抑制剂，这可能适用于多种病理状态。
