Direct involvement of cAMP-dependent protein kinase in the regulation of alkaline phosphatase activity by parathyroid hormone (PTH) and PTH-related peptide in osteoblastic UMR-106 cells.
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.
Kano
J
J
Department of Medicine, Kobe University School of Medicine, Japan.
Sugimoto
T
T
Fukase
M
M
Chihara
K
K
D000469:Alkaline Phosphatase / Q000378:metabolism*; D002118:Calcium / Q000502:physiology; D000242:Cyclic AMP / Q000502:physiology; D017868:Cyclic AMP-Dependent Protein Kinases / Q000502:physiology*; D004789:Enzyme Activation; D006801:Humans; D066298:In Vitro Techniques; D007476:Ionophores / Q000494:pharmacology; D010006:Osteoblasts / Q000201:enzymology*; D010281:Parathyroid Hormone / Q000502:physiology*; D044162:Parathyroid Hormone-Related Protein; D011506:Proteins / Q000494:pharmacology*; D015398:Signal Transduction; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology
D007476:Ionophores; C470121:PTHLH protein, human; D010281:Parathyroid Hormone; D044162:Parathyroid Hormone-Related Protein; D011506:Proteins; D000242:Cyclic AMP; D017868:Cyclic AMP-Dependent Protein Kinases; D000469:Alkaline Phosphatase; D013755:Tetradecanoylphorbol Acetate; D002118:Calcium