Komatsu Nahoko, Takata Minoru, Otsuki Norio, Toyama Tadashi, Ohka Rie, Takehara Kazuhiko, Saijoh Kiyofumi
Department of Dermatology, Graduate School of Medical Science, School of Medicine, Kanazawa University, 13-1 Takara-machi, Kanazawa 920-8641, Japan.
J Invest Dermatol. 2003 Sep;121(3):542-9. doi: 10.1046/j.1523-1747.2003.12363.x.
Tissue kallikreins are a group of serine proteases that are found in many organs and biologic fluids. Tissue kallikrein genes (KLKs) are found on chromosome 19q13.3-4 as a gene cluster encoding 15 different serine proteases. In skin, two tissue kallikrein proteins, hK5 and hK7, are expressed in the stratum corneum and are known to be involved in desquamation of corneocytes. The possible involvement of other kallikrein proteins has not been clarified, however, nor has the significance of each member in the serine protease activity of skin been delineated. In the study described here, we examined expression and localization of KLK mRNA in normal human skin by means of RT-PCR and in situ hybridization. Quantitative RT-PCR analysis showed abundant expression of KLK1 and KLK11 mRNA, moderate expression of KLK4, KLK5, KLK6, KLK7, and KLK13 mRNA, and low expression of KLK8 mRNA in normal human skin. For KLK4, KLK8, and KLK13 mRNA, splice variants were identified to be their major mRNA species. Two variants for KLK13 mRNA were novel. The amount of the serine protease inhibitor Kazal-type 5 (SPINK5) mRNA was comparable to KLK1 and KLK11 mRNA. In situ hybridization revealed intense expression of all KLK mRNA studied except KLK12 mRNA in the stratum granulosum of normal epidermis, where SPINK5 mRNA coexisted. Excluding KLK13 mRNA, they are also expressed in hair sheath, eccrine sweat glands, and sebaceous glands. Coexpression of various KLK and SPINK5 mRNA suggests that their proteins are the candidates to balance and maintain serine protease activities in both the skin and appendages.
组织激肽释放酶是一类丝氨酸蛋白酶，存在于许多器官和生物体液中。组织激肽释放酶基因（KLKs）位于19号染色体q13.3 - 4上，形成一个基因簇，编码15种不同的丝氨酸蛋白酶。在皮肤中，两种组织激肽释放酶蛋白，即hK5和hK7，在角质层中表达，已知它们参与角质形成细胞的脱屑过程。然而，其他激肽释放酶蛋白的可能作用尚未阐明，皮肤中各成员在丝氨酸蛋白酶活性方面的意义也未明确界定。在本研究中，我们通过逆转录聚合酶链反应（RT-PCR）和原位杂交技术检测了正常人皮肤中KLK mRNA的表达和定位。定量RT-PCR分析显示，正常人皮肤中KLK1和KLK11 mRNA表达丰富，KLK4、KLK5、KLK6、KLK7和KLK13 mRNA表达中等，KLK8 mRNA表达较低。对于KLK4、KLK8和KLK13 mRNA，剪接变体被确定为其主要的mRNA种类。KLK13 mRNA的两种变体是新发现的。丝氨酸蛋白酶抑制剂Kazal型5（SPINK5）mRNA的量与KLK1和KLK11 mRNA相当。原位杂交显示，除KLK12 mRNA外，所有研究的KLK mRNA在正常表皮颗粒层中均有强烈表达，SPINK5 mRNA也共存于此。除KLK13 mRNA外，它们在毛鞘、小汗腺和皮脂腺中也有表达。多种KLK和SPINK5 mRNA的共表达表明，它们的蛋白质可能是平衡和维持皮肤及附属器中丝氨酸蛋白酶活性的候选物质。
