Proteases and Tissue Remodeling Section, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD, United States of America.
PLoS One. 2018 Apr 4;13(4):e0194660. doi: 10.1371/journal.pone.0194660. eCollection 2018.
Prostasin (CAP1/PRSS8) is a glycosylphosphatidylinositol (GPI)-anchored serine protease that is essential for epithelial development and overall survival in mice. Prostasin is regulated primarily by the transmembrane serine protease inhibitor, hepatocyte growth factor activator inhibitor (HAI)-2, and loss of HAI-2 function leads to early embryonic lethality in mice due to an unregulated prostasin activity. We have recently reported that critical in vivo functions of prostasin can be performed by proteolytically-inactive or zymogen-locked variants of the protease. Here we show that the zymogen form of prostasin does not bind to HAI-2 and, as a result, loss of HAI-2 does not affect prenatal development and survival of mice expressing only zymogen-locked variant of prostasin (Prss8 R44Q). Indeed, HAI-2-deficient mice homozygous for R44Q mutation (Spint2-/-;Prss8R44Q/R44Q) are born in the expected numbers and do not exhibit any obvious developmental abnormality at birth. However, postnatal growth in these mice is severely impaired and they all die within 4 to 7 days after birth due to a critical failure in the development of small and large intestines, characterized by a widespread villous atrophy, tufted villi, near-complete loss of mucin-producing goblet cells, loss of colonic crypt structure, and bleeding into the intestinal lumen. Intestines of Spint2-/-;Prss8R44Q/R44Q mice showed altered expression of epithelial junctional proteins, including reduced levels of EpCAM, E-cadherin, occludin, claudin-1 and -7, as well as an increased level of claudin-4, indicating that the loss of HAI-2 compromises intestinal epithelial barrier function. Our data indicate that the loss of HAI-2 in Prss8R44Q/R44Q mice leads to development of progressive intestinal failure that at both histological and molecular level bears a striking resemblance to human congenital tufting enteropathy, and may provide important clues for understanding and treating this debilitating human disease.
前列腺素原（CAP1/PRSS8）是一种糖基磷脂酰肌醇（GPI）锚定丝氨酸蛋白酶，对小鼠的上皮发育和整体存活至关重要。前列腺素原主要受跨膜丝氨酸蛋白酶抑制剂，肝细胞生长因子激活物抑制剂（HAI）-2 调节，由于前列腺素原活性不受调节，HAI-2 功能丧失会导致小鼠早期胚胎致死。我们最近报道，前列腺素原的关键体内功能可以由蛋白酶的无活性或酶原锁定变体来执行。在这里，我们表明，前列腺素原的酶原形式不与 HAI-2 结合，因此，HAI-2 的缺失不会影响仅表达酶原锁定变体的前列腺素原（Prss8 R44Q）的小鼠的产前发育和存活。事实上，HAI-2 缺陷型杂合子 R44Q 突变（Spint2-/-；Prss8R44Q/R44Q）的小鼠以预期的数量出生，出生时没有任何明显的发育异常。然而，这些小鼠的出生后生长严重受损，由于小肠和大肠的发育严重失败，它们都在出生后 4 至 7 天内死亡，其特征是绒毛萎缩广泛、簇状绒毛、粘液产生的杯状细胞几乎完全丧失、结肠隐窝结构丧失和肠腔出血。Spint2-/-；Prss8R44Q/R44Q 小鼠的肠组织显示上皮连接蛋白的表达改变，包括 EpCAM、E-钙粘蛋白、occludin、claudin-1 和 -7 的水平降低，以及 claudin-4 的水平升高，表明 HAI-2 的缺失会损害肠道上皮屏障功能。我们的数据表明，Prss8R44Q/R44Q 小鼠中 HAI-2 的缺失导致进行性肠衰竭的发展，在组织学和分子水平上与人先天性簇状肠病非常相似，这可能为理解和治疗这种使人衰弱的人类疾病提供重要线索。
