The expression of human loricrin gene

兜甲蛋白是皮质细胞被膜的主要成分。兜甲蛋白首先出现在透明角质颗粒中，随后被纳入CE中。顺便说一下，在各种遗传性角化疾病中，仅在大疱性先天性鱼鳞病样红皮病、某些类型的板层状鱼鳞病、某些类型的掌跖角化病、Sjogren-Larsson综合征和Vohwinkel综合征中发现了相关基因的点突变。Vohwinkel综合征目前认为是由兜甲蛋白基因点突变引起的。由于兜甲蛋白是CE的主要成分，了解兜甲蛋白基因在正常和异常角化条件下的表达不仅有助于Vohwinkel综合征的诊断和治疗，而且有助于对各种角化疾病的深入了解。本实验将FRSK细胞、正常人表皮角朊细胞（NHEK）、Pam 212细胞和HaCaT细胞在高钙培养基中培养，观察CE的形成。我们发现HaCaT细胞在高钙培养液中可以形成CE，并检测了兜甲蛋白和转氨酶1的表达。众所周知，兜甲蛋白在NHEK细胞中几乎检测不到。相反，兜甲蛋白在高钙培养基中培养的HaCaT细胞中大量表达。因此，在高钙培养基中培养的HaCaT细胞类似于体内表皮。HaCaT细胞非常适合于兜甲蛋白表达和表皮角化的研究。

Loricrin is a major constituent of cornified cell envelope (CE). Loricrin appears at keratohyalin granules at first and is subsequently incorporated into CE.By the way, amongst various hereditary keratinizing disorders, the point mutations of responsible genes were identified only in bullous congenital ichthyosiform erythroderma, some types of lamellar ichthyosis, some types of palmoplantar keratoderma, Sjogren-Larsson syndrome and Vohwinkel syndrome. Vohwinkel syndrome is now thought to be due to the point mutation of loricrin gene. Because loricrin is the major constituent of CE,to understand the expression of loricrin gene in normal and abnormal keratinizing conditions not only facilitates the diagnosis and therapy of Vohwinkel syndrome but also encourages the deep understanding of wide variety of keratinizing disorders. We cultured FRSK cells, normal human epidermal kerationcytes (NHEK), Pam 212 and HaCaT cells in high calcium medium and checked whether CE was formed or not. We found HaCaT cells cultured in high calcium medium could form CE.We also checked the expression of loricrin and transglutaminase 1. It is well known that loricrin is hardly detectable in NHEK cells. In contrast loricrin is abundantly expressed in HaCaT cells cultured in high calcium medium. Thus HaCaT cells cultured in high calcium medium resemble in vivo epidermis. Thus HaCaT cells are very suitable for the research in the expression of loricrin and epidermal keratinization.