Iida-Klein A, Varlotta V, Hahn T J
Department of Medicine, Wadsworth VA Medical Center, Los Angeles, CA.
J Bone Miner Res. 1989 Oct;4(5):767-74. doi: 10.1002/jbmr.5650040517.
The calcium and phospholipid-dependent protein kinase C (PKC) system appears to play an important role in mediating hormonal effects in various tissues including bone. Accordingly, we characterized PKC activity in the UMR-106-01 rat osteosarcoma osteoblastlike cell line and examined its hormonal regulation. UMR-106-01 cells were found to possess a classic, phorbol ester-activated PKC system, which was highly calcium and phospholipid dependent. A 30 s exposure to 10 nM bovine parathyroid hormone (PTH) (1-34) increased cytosolic and membrane-bound PKC activity by 12 and 157%, respectively, resulting in a 2.2-fold increase in the membrane-bound to cytosolic (MB/C) activity ratio (all p less than 0.01). The MB/C activity ratio was highest at 20 min, exhibiting a 2.8-fold increase over the control values (p less than 0.01). In contrast, 10 nM insulin increased cytosolic PKC activity but decreased membrane-bound activity, resulting in a 61% decrease in the MB/C activity ratio at 20 min (p less than 0.02). Moreover, insulin reduced PTH stimulation of the PKC activity ratio by 42 and 62% at 30 s and 20 min, respectively (p less than 0.02). Thus, PTH and insulin have opposing effects on the PKC activity ratio in UMR-106-01 cells.
钙和磷脂依赖性蛋白激酶C（PKC）系统似乎在介导包括骨骼在内的各种组织中的激素效应方面发挥着重要作用。因此，我们对UMR-106-01大鼠骨肉瘤成骨样细胞系中的PKC活性进行了表征，并研究了其激素调节作用。发现UMR-106-01细胞具有经典的、佛波酯激活的PKC系统，该系统高度依赖钙和磷脂。暴露于10 nM牛甲状旁腺激素（PTH）（1-34）30秒后，胞质和膜结合的PKC活性分别增加了12%和157%，导致膜结合与胞质（MB/C）活性比增加了2.2倍（所有p均小于0.01）。MB/C活性比在20分钟时最高，比对照值增加了2.8倍（p小于0.01）。相比之下，10 nM胰岛素增加了胞质PKC活性，但降低了膜结合活性，导致20分钟时MB/C活性比降低了61%（p小于0.02）。此外，胰岛素在30秒和20分钟时分别使PKC活性比的PTH刺激降低了42%和62%（p小于0.02）。因此，PTH和胰岛素对UMR-106-01细胞中的PKC活性比具有相反的作用。
