Sugimoto T, Kano J, Yamaguchi T, Fukase M, Chihara K
Department of Medicine, Kobe University School of Medicine, Japan.
Horm Metab Res. 1993 Dec;25(12):608-11. doi: 10.1055/s-2007-1002189.
Our recent study demonstrated the direct involvement of cAMP-dependent protein kinase (PKA) in the regulation of DNA synthesis by PTH-related peptide (PTHrP) in osteoblastic osteosarcoma cells, UMR-106. Since PTHrP has been reported to possess dual signal transduction systems [PKA and calcium/protein kinase C (Ca/PKC]), present study was performed to characterize the involvement of Ca/PKC signal transduction system in the regulation of DNA synthesis by PTHrP in these cells. Human PTHrP-(1-34) (10(-7) M) caused a rapid increase in intracellular Ca ([Ca2+]i), followed by return to the basal level within 1 min. Pretreatment with 10(-4) M TMB-8 or 10(-5) M dantrolene, inhibitors of calcium release from intracellular calcium store, significantly blocked the PTHrP-induced increase in [Ca2+]i, but did not affect the PTHrP-induced inhibition of DNA synthesis. Pretreatment with 50 uM H-7 or 1 nM staurosporine, inhibitors of PKC, significantly blocked the PTHrP (10(-9) to 10(-7) M)-induced inhibition of DNA synthesis. Pretreatment with 10(-6) M phorbol 12-myristate 13-acetate, which downregulated PKC, significantly blocked the inhibition of DNA synthesis by PTHrP. Present study indicates that in addition to PKA activation, PKC activation is coupled to the regulation of DNA synthesis by PTHrP in osteoblasts.
我们最近的研究表明，环磷酸腺苷依赖性蛋白激酶（PKA）直接参与成骨细胞性骨肉瘤细胞UMR-106中甲状旁腺激素相关肽（PTHrP）对DNA合成的调节。由于据报道PTHrP具有双重信号转导系统[PKA和钙/蛋白激酶C（Ca/PKC）]，因此进行本研究以表征Ca/PKC信号转导系统在这些细胞中PTHrP对DNA合成调节中的作用。人PTHrP-(1-34)（10^(-7) M）导致细胞内钙（[Ca2+]i）迅速增加，随后在1分钟内恢复到基础水平。用10^(-4) M TMB-8或10^(-5) M丹曲林（细胞内钙储存钙释放抑制剂）预处理，可显著阻断PTHrP诱导的[Ca2+]i增加，但不影响PTHrP诱导的DNA合成抑制。用50 μM H-7或1 nM星形孢菌素（PKC抑制剂）预处理，可显著阻断PTHrP（10^(-9)至10^(-7) M）诱导的DNA合成抑制。用10^(-6) M佛波醇12-肉豆蔻酸酯13-乙酸酯（下调PKC）预处理，可显著阻断PTHrP对DNA合成的抑制。本研究表明，除了PKA激活外，PKC激活还与成骨细胞中PTHrP对DNA合成的调节相关。
