Evidence for separate control mechanisms at the message, protein, and enzyme activation levels for transglutaminase during calcium-induced differentiation of normal and transformed human keratinocytes
Evidence for separate control mechanisms at the message, protein, and enzyme activation levels for transglutaminase during calcium-induced differentiation of normal and transformed human keratinocytes
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DOI：
10.1111/1523-1747.ep12329856
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发表时间：
1996-01-01
影响因子：
6.5
通讯作者：
Bikle, DD
中科院分区：
文献类型：
--
作者：
Gibson, DFC;Ratnam, AV;Bikle, DD
我们分析了三种不同的钙浓度对RNA和功能蛋白水平的转氨酶（TGase）和外皮蛋白（INV）随着时间的推移，在文化，我们比较了结果在正常人角质形成细胞与鳞状细胞癌，SCC 4。最高钙浓度（1.2mM）诱导最大水平的INV和TGase信息、INV蛋白和CE形成速率，但不是最大水平的TGase蛋白。通过检查角质形成细胞的胞质和膜组分，我们发现，在合成后，在钙的影响下，TGase蛋白发生变化，然而，只有1.2mM的钙诱导显著量的TGase活性。这些数据表明，升高的钙（1.2 mM）不仅通过调节INV和TGase信息水平，而且通过调节TGase蛋白的翻译和活化，实现了角质形成细胞分化的预期诱导。我们的数据表明，这种钙诱导的TGase蛋白的激活发生，而蛋白质锚定在膜上。相反，尽管SCC 4细胞内有充足的INV和TGase信息水平，但这些RNA水平不受钙调节或翻译成蛋白质，这表明SCC 4细胞的转化表型不仅导致钙不能调节基因转录，而且导致这些分化特异性蛋白质的翻译机制存在缺陷。
We analyzed the effects of three different calcium concentrations on the RNA and functional protein levels of transglutaminase (TGase) and involucrin (INV) over time in culture, We compared the results in normal human keratinocytes with those in a squamous cell carcinoma, SCC4. The highest calcium concentration (1.2 mM) induced the greatest levels of INV and TGase message, INV protein, and rates of CE formation, but not maximal levels of TGase protein, By examining cytosol and membrane fractions of keratinocytes, we found that after synthesis, TGase protein shifts, under the influence of calcium (both 0.1 mM and 1.2 mM), from the cytosol into the membrane in postconfluent cells, However, only 1.2 mM calcium induced significant amounts of TGase activity. These data indicate that elevated calcium (1.2 mM) achieves the expected induction in keratinocyte differentiation by regulation of not only INV and TGase message levels, but also the translation and activation of TGase protein. Our data suggest that this calcium-induced activation of TGase protein occurs while the protein is anchored in the membrane. In contrast, despite ample INV and TGase message levels within SCC4 cells, these RNA levels are not regulated by calcium or translated into protein, suggesting that the transformed phenotype of SCC4 cells results not only in a failure of calcium to regulate gene transcription, but also in a defect within the translation machinery of these differentiation-specific proteins.