Abstract：
Nagashima-type palmoplantar keratoderma (NPPK) is an autosomal recessive genodermatosis caused by loss-of-function variants in SERPINB7 and is the most prevalent form of inherited palmoplantar keratodermas among Asians. However, there is currently no effective therapy for NPPK because its pathogenesis remains unclear. In this study, Serpinb7-/- mice were generated and spontaneously developed a disrupted skin barrier, which was further exacerbated by acetone-ether-water treatment. The skin of these Serpinb7-/- mice showed weakened cytoskeletal proteins. Additionally, SERPINB7 deficiency consistently led to decreased epidermal differentiation in a three-dimensional human epidermal model. We also demonstrated that SERPINB7 was an inhibitory serpin that mainly inhibited the protease legumain. SERPINB7 bound directly with legumain and inhibited legumain activity both in vitro and in vivo. Furthermore, we found that SERPINB7 inhibited legumain in a \'protease-substrate\' manner and identified the cleavage sites of SERPINB7 as Asn71 and Asn343. Overall, we found that SERPINB7 showed the nature of a cysteine protease inhibitor, and identified legumain as a key target protease of SERPINB7. Loss of SERPINB7 function led to overactivation of legumain, which might disrupt cytoskeletal proteins, contributing to the impaired skin barrier in NPPK. These findings may lead to the development of therapeutic strategies for NPPK.
摘要：
Nagashima型掌plant角膜皮病（NPPK）是由SERPINB7功能丧失变异引起的常染色体隐性遗传病，是亚洲人遗传性掌plant角膜皮病的最普遍形式。然而,目前尚无有效的NPPK治疗方法,因为其发病机制尚不清楚.在这项研究中,Serpinb7-/-小鼠产生并自发形成破坏的皮肤屏障，丙酮-乙醚-水处理进一步加剧了这种情况。这些Serpinb7-/-小鼠的皮肤显示出减弱的细胞骨架蛋白。此外,在三维人类表皮模型中，SERPINB7缺乏始终导致表皮分化降低。我们还证明了SERPINB7是主要抑制蛋白酶legumain的抑制性serpin。SERPINB7在体外和体内直接与豆蔻素结合并抑制豆蔻素活性。此外，我们发现SERPINB7以“蛋白酶-底物”方式抑制legumain，并将SERPINB7的切割位点鉴定为Asn71和Asn343。总的来说,我们发现SERPINB7显示了半胱氨酸蛋白酶抑制剂的性质，并鉴定了生豆素是SERPINB7的关键靶蛋白酶。SERPINB7功能的丧失导致了豆素的过度激活，这可能会破坏细胞骨架蛋白，导致NPPK皮肤屏障受损。这些发现可能导致NPPK治疗策略的发展。
