Cho J K, Bikle D D
Department of Medicine, University of California, San Francisco, USA.
J Cell Physiol. 1997 Aug;172(2):146-54. doi: 10.1002/(SICI)1097-4652(199708)172:2<146::AID-JCP2>3.0.CO;2-O.
Ca2+ regulates keratinocyte differentiation by increasing intracellular Ca2+ levels. Ca(2+)-ATPase in the Ca(2+)-induced differentiation of human keratinocytes was investigated by measuring Ca(2+)-ATPase mRNA, protein, and activity levels. Human keratinocytes were grown in Keratinocyte Growth Medium containing 0.03, 0.1, or 1.2 mM Ca2+ and assayed on days 2, 5, 7, 14, and 21. Ca(2+)-ATPase mRNA levels were found to be modestly increased in 5-, 7-, and 14-day cultured cells as compared with 2-day cultured cells, but levels fell below that of the 2-day cultured cells in the 21-day cultured cells. The Ca(2+)-ATPase mRNA levels were not affected by Ca2+ levels. A 135-kDa protein in human keratinocytes cross reacted with the monoclonal antibody against human erythrocyte Ca(2+)-ATPase. The level of this protein was decreased by Ca2+ and lost during differentiation, in parallel with the loss of enzymatic activity. Ca2+ influx of postconfluent 1.2 mM Ca(2+)-grown cells was higher than that of cells grown in lower Ca2+ concentrations. Ca2+ efflux from postconfluent cells grown in 0.03 mM Ca2+ was less than that from cells grown in stronger Ca2+ concentrations. These results suggest that the loss of the plasma membrane Ca(2+)-ATPase with time in culture contributes to the rise in intracellular Ca2+, thus promoting keratinocyte differentiation.
钙离子通过提高细胞内钙离子水平来调节角质形成细胞的分化。通过测量钙离子 - ATP酶的mRNA、蛋白质和活性水平，研究了钙离子诱导人角质形成细胞分化过程中的钙离子 - ATP酶。人角质形成细胞在含有0.03、0.1或1.2 mM钙离子的角质形成细胞生长培养基中培养，并在第2、5、7、14和21天进行检测。与培养2天的细胞相比，发现培养5天、7天和14天的细胞中钙离子 - ATP酶的mRNA水平适度增加，但在培养21天的细胞中该水平低于培养2天的细胞。钙离子 - ATP酶的mRNA水平不受钙离子浓度的影响。人角质形成细胞中的一种135 kDa蛋白质与抗人红细胞钙离子 - ATP酶的单克隆抗体发生交叉反应。该蛋白质的水平因钙离子而降低，并在分化过程中丧失，与酶活性的丧失平行。汇合后在1.2 mM钙离子浓度下培养的细胞的钙离子内流高于在较低钙离子浓度下培养的细胞。在0.03 mM钙离子浓度下培养的汇合后细胞的钙离子外流少于在较高钙离子浓度下培养的细胞。这些结果表明，培养过程中质膜钙离子 - ATP酶随时间的丧失有助于细胞内钙离子的升高，从而促进角质形成细胞的分化。
