Department of Clinical Pharmacokinetics, Hoshi University.
Biol Pharm Bull. 2013;36(10):1615-21. doi: 10.1248/bpb.b13-00494. Epub 2013 Aug 2.
Aquaporin-3 (AQP3) plays an important role in maintaining the normal water content of the skin. Previously, we revealed that the expression of cutaneous AQP3 increased following oral administration of Gypsum fibrosum (main component: CaSO₄) to mice. The purpose of this study is to elucidate the mechanism by which Gypsum fibrosum increases the expression of cutaneous AQP3 in a keratinocyte cell line. Gypsum fibrosum or CaSO₄ was added to keratinocytes, and the expression level of AQP3, the Ca concentration, the activity of protein kinase C (PKC), and the degrees of phosphorylation of both extracellular signal-regulated kinase (ERK) and cAMP response element binding protein (CREB) were measured. The mRNA and protein expression levels of AQP3 increased significantly 6 h-post addition of Gypsum fibrosum. In keratinocytes treated with Gypsum fibrosum, increases in the concentration of intracellular Ca, PKC activity, and the phosphorylation of ERK and CREB were observed. Pre-treatment with GF109203X, a PKC inhibitor, suppressed the mRNA expression levels of AQP3. Similarly to treatment with Gypsum fibrosum, the addition of CaSO₄ led to the same observations in keratinocytes. It is hypothesized that Gypsum fibrosum causes an increase in the intracellular Ca concentration, PKC activity, and the phosphorylation levels of ERK and CREB, resulting in increased AQP3 expression in keratinocytes. In addition, it is possible that the effect of Gypsum fibrosum is attributable to CaSO₄, based on the results demonstrating that the mechanisms of action of Gypsum fibrosum and CaSO₄ were nearly identical.
水通道蛋白 3（AQP3）在维持皮肤正常含水量方面发挥着重要作用。我们之前曾揭示，给小鼠口服石膏（主要成分为 CaSO₄）后，皮肤 AQP3 的表达增加。本研究的目的是阐明石膏增加角质形成细胞系中皮肤 AQP3 表达的机制。将石膏或 CaSO₄ 添加到角质形成细胞中，测量 AQP3 的表达水平、Ca 浓度、蛋白激酶 C（PKC）活性以及细胞外信号调节激酶（ERK）和 cAMP 反应元件结合蛋白（CREB）的磷酸化程度。添加石膏后 6 小时，AQP3 的 mRNA 和蛋白表达水平显著增加。在用石膏处理的角质形成细胞中，观察到细胞内 Ca 浓度、PKC 活性以及 ERK 和 CREB 的磷酸化增加。PKC 抑制剂 GF109203X 的预处理抑制了 AQP3 的 mRNA 表达水平。与用石膏处理相似，向角质形成细胞中添加 CaSO₄ 也导致了相同的观察结果。据推测，石膏导致细胞内 Ca 浓度、PKC 活性以及 ERK 和 CREB 的磷酸化水平增加，从而导致角质形成细胞中 AQP3 的表达增加。此外，根据石膏和 CaSO₄ 的作用机制几乎相同的结果，推测石膏的作用可能归因于 CaSO₄。
