THAPSIGARGIN RAISES INTRACELLULAR FREE CALCIUM LEVELS IN HUMAN KERATINOCYTES AND INHIBITS THE COORDINATED EXPRESSION OF DIFFERENTIATION MARKERS
THAPSIGARGIN RAISES INTRACELLULAR FREE CALCIUM LEVELS IN HUMAN KERATINOCYTES AND INHIBITS THE COORDINATED EXPRESSION OF DIFFERENTIATION MARKERS
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DOI：
10.1006/excr.1994.1011
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发表时间：
1994-01-01
影响因子：
3.7
通讯作者：
SHARPE, GR
中科院分区：
文献类型：
--
作者：
JONES, KT;SHARPE, GR
毒胡萝卜素通过有效抑制内质网Ca-ATP酶来提高细胞内游离钙（[Ca 2 +]i），内质网Ca-ATP酶从细胞质中螯合钙。在人角质形成细胞中，[Ca 2 +] i的升高与分化有关，因此我们研究了毒胡萝卜素对这一过程的作用。在浓度高于3 nMthapsigargin抑制角质形成细胞增殖。Thapsigargin在无钙或70 μ M钙介质中引起瞬时[Ca ~（2+）]升高，但在2 mM钙介质中引起更长时间的升高。对于在70 μ M钙培养基中培养的角质形成细胞，在6小时后也观察到迟发性[Ca ~（2+）] i升高，类似于已知的分化刺激物的作用。然而，免疫组化技术没有显示任何表达的分化特异性蛋白involucrin，一个组成部分的corneal包膜。当细胞外钙离子浓度从70 μ M增加到2 mM时，角质形成细胞分化，大量的外皮蛋白和桥粒斑蛋白（桥粒的一种成分）被合成。这两种蛋白质的染色模式，建议纳入结构蛋白，但毒胡萝卜素破坏钙诱导的模式外皮蛋白和桥粒斑蛋白的合成。毒胡萝卜素没有诱导分化，可能是由于它不能激活蛋白激酶C和提高肌醇三磷酸水平。我们的结论是，[Ca 2 +] i的上升并不单独诱导角质形成细胞分化，但可能与其他细胞内信号，以促进分化。
Thapsigargin raises intracellular free calcium ([Ca2+]i) by potently inhibiting the endoplasmic reticulum Ca-ATPase, which sequesters calcium from the cytosol. In human keratinocytes a rise in [Ca2+]ihas been associated with differentiation and therefore we investigated the action of thapsigargin on this process. At concentrations above 3 nMthapsigargin inhibited keratinocyte proliferation. Thapsigargin induced an immediate transient [Ca2+]irise in calcium-free or 70 μMcalcium medium but a more prolonged rise in 2 mMcalcium. For keratinocytes cultured in 70 μMcalcium medium a late [Ca2+]irise was also observed, after 6 h, similar to the effect of known differentiation stimuli. However, immunohistochemical techniques did not show any expression of the differentiation-specific protein involucrin, a component of the cornified envelope. When keratinocyte differentiation was induced by an increase in the extracellular calcium from 70 μMto 2 mMabundant involucrin and desmoplakin, a component of desmosomes, were synthesised. Both proteins gave staining patterns which suggested incorporation into structural proteins, but thapsigargin disrupted the calcium-induced pattern of involucrin and desmoplakin synthesis. Thapsigargin did not induce differentiation, possibly due to its inability to activate protein kinase C and raise inositol trisphosphate levels. We conclude that a rise in [Ca2+]idoes not alone induce keratinocyte differentiation but may act with other intracellular signals to promote differentiation.