Kano J, Sugimoto T, Fukase M, Chihara K
Department of Medicine, Kobe University School of Medicine, Japan.
Biochem Biophys Res Commun. 1994 Feb 28;199(1):271-6. doi: 10.1006/bbrc.1994.1224.
The present study was performed to characterize the participation of parathyroid hormone (PTH)- and PTH-related peptide (PTHrP)-responsive dual signal transduction systems [cAMP-dependent protein kinase (PKA) and Calcium/protein kinase C (Ca/PKC)] in the regulation of alkaline phosphatase (ALP) activity in osteoblastic osteosarcoma cells (UMR-106). Both human (h) PTH-(1-34) and hPTHrP-(1-34) at 10(-8) M stimulated ALP activity to the similar degree. Dibutyryl, cAMP (dbcAMP) (10(-5), 10(-4) M) and Sp-diastereoisomer of adenosine cyclic 3',5'-phosphorothioate (Sp-cAMPS), a direct stimulator of PKA (10(-4) M) also stimulated its activity. Phorbol 12-myristate 13-acetate (PMA), an activator of PKC, (10(-7), 10(-6) M) did not affect its activity, while calcium ionophores, A23187 and ionomycin (10(-7), 10(-6) M) inhibited it. Although Rp-diastereoisomer of adenosine cyclic 3',5'-phosphorothioate (Rp-cAMPS), a direct inhibitor of PKA, (10(-4) M) did not affect ALP activity by itself, it significantly antagonized not only Sp-cAMPS-induced increase in ALP activity, but also PTH- and PTHrP-induced one. The present study first indicated that the activation of PKA was directly involved and acted as a main pathway in the regulation of ALP activity by PTH and PTHrP in osteoblasts.
本研究旨在表征甲状旁腺激素（PTH）和甲状旁腺激素相关肽（PTHrP）反应性双信号转导系统[环磷酸腺苷依赖性蛋白激酶（PKA）和钙/蛋白激酶C（Ca/PKC）]在成骨骨肉瘤细胞（UMR-106）中碱性磷酸酶（ALP）活性调节中的参与情况。10⁻⁸ M的人（h）PTH-（1-34）和hPTHrP-（1-34）对ALP活性的刺激程度相似。二丁酰环磷酸腺苷（dbcAMP）（10⁻⁵、10⁻⁴ M）和腺苷环3',5'-硫代磷酸酯的Sp-非对映异构体（Sp-cAMPS），一种PKA的直接刺激剂（10⁻⁴ M）也刺激了其活性。蛋白激酶C的激活剂佛波酯12-肉豆蔻酸酯13-乙酸酯（PMA）（10⁻⁷、10⁻⁶ M）不影响其活性，而钙离子载体A23187和离子霉素（10⁻⁷、10⁻⁶ M）则抑制其活性。尽管腺苷环3',5'-硫代磷酸酯的Rp-非对映异构体（Rp-cAMPS），一种PKA的直接抑制剂（10⁻⁴ M）本身不影响ALP活性，但它不仅显著拮抗Sp-cAMPS诱导的ALP活性增加，还显著拮抗PTH和PTHrP诱导的增加。本研究首次表明，PKA的激活直接参与并作为成骨细胞中PTH和PTHrP调节ALP活性的主要途径。
