Guesdon F, Waller R J, Saklatvala J
Department of Development and Cell Signalling, Babraham Institute, Cambridge, U.K.
Biochem J. 1994 Dec 15;304 ( Pt 3)(Pt 3):761-8. doi: 10.1042/bj3040761.
Increases (5-fold) in the rate of phosphorylation of beta-casein were observed in extracts of human gingival fibroblasts that had been stimulated by interleukin 1 (IL-1) or tumour necrosis factor (TNF). The induced kinase was cytosolic and had little activity on alpha-casein. Its chromatographic behaviour on anion-exchange and gel-filtration columns was similar to that of beta-casein kinase, an enzyme detected originally in MRC-5 cells stimulated by IL-1 and TNF. Phosphopeptide maps of beta-casein confirmed that the kinase activated in gingival fibroblasts had the same substrate specificity as beta-casein kinase. In gingival fibroblasts, beta-casein kinase activity was maximum after 15 min of stimulation by IL-1 or TNF, and remained activated for several hours. Activations of small heat-shock protein (hsp27) kinase and mitogen-activated protein (MAP) kinase were also maximum 15 min after stimulation, but decreased to background levels within the next 30 min. Study of the effects of 21 agents other than IL-1 or TNF showed that none activated beta-casein kinase, whereas several activated MAP kinase or hsp27 kinase. beta-Casein kinase was also detected in extracts of bovine articular chondrocytes and human endothelial cells stimulated by IL-1 or TNF. Semi-purified preparations of fibroblast beta-casein kinase were not inactivated by phosphatases in vitro. Our results suggest that it may be involved in responses specific to IL-1 and TNF in a wide range of cell types and that its activation probably involves mechanisms other than its phosphorylation.
在受到白细胞介素1（IL-1）或肿瘤坏死因子（TNF）刺激的人牙龈成纤维细胞提取物中，观察到β-酪蛋白磷酸化速率增加了（5倍）。诱导的激酶存在于胞质溶胶中，对α-酪蛋白几乎没有活性。其在阴离子交换柱和凝胶过滤柱上的色谱行为与β-酪蛋白激酶相似，β-酪蛋白激酶最初是在受IL-1和TNF刺激的MRC-5细胞中检测到的一种酶。β-酪蛋白的磷酸肽图谱证实，牙龈成纤维细胞中激活的激酶与β-酪蛋白激酶具有相同的底物特异性。在牙龈成纤维细胞中，IL-1或TNF刺激15分钟后，β-酪蛋白激酶活性最高，并在数小时内保持激活状态。小热休克蛋白（hsp27）激酶和丝裂原活化蛋白（MAP）激酶的激活在刺激后15分钟时也最高，但在接下来的30分钟内降至背景水平。对除IL-1或TNF之外的21种试剂的作用研究表明，没有一种能激活β-酪蛋白激酶，而有几种能激活MAP激酶或hsp27激酶。在受IL-1或TNF刺激的牛关节软骨细胞和人内皮细胞提取物中也检测到了β-酪蛋白激酶。成纤维细胞β-酪蛋白激酶的半纯化制剂在体外不会被磷酸酶灭活。我们的结果表明，它可能参与多种细胞类型中对IL-1和TNF的特异性反应，其激活可能涉及除磷酸化以外的机制。
