title: Calyculin A stimulates the expression of TNF-alpha mRNA via phosphorylation of Akt in mouse osteoblastic MC3T3-E1 cells.
abstract: Intracellular phosphatase activity has been recognized to play a central role in signal transduction. In the present study, we investigated the effects of calyculin A, an inhibitor of protein phosphatases, on the expression of TNF-alpha mRNA and the possible signaling pathways in mouse osteoblastic MC3T3-E1 cells. The result of semiquantitative RT-PCR showed that calyculin A increased the expression of TNF-alpha mRNA in MC3T3-E1 cells. Pre-treatment of LY294002 and Wortmannin, inhibitors of PI3K, inhibited the calyculin A-stimulated TNF-alpha mRNA expression. Western blot result disclosed that calyculin A increased the phosphorylation status of Akt at Ser473. However, U0126 and SB203580, specific inhibitor of MEK1/2 and p38MAPK, respectively, had no effect on calyculin A-stimulated expression of TNF-alpha mRNA. BAY11-7085 and CAPE, inhibitors of NF-kappaB activity, did not alter the calyculin A-stimulated TNF-alpha mRNA expression. Indirect immunofluorescent study confirmed that NF-kappaB was not translocated to the nucleus by calyculin A treatment. Our present results suggest that inhibition of phosphatase activity by calyculin A stimulate the phosphorylation of Akt at Ser473 by PI3K/Akt signaling pathway, resulting in the expression TNF-alpha mRNA.
authors.affiliation: Department of Histology and Oral Histology, Institute of Health Biosciences, The University of Tokushima Graduate School, 3-18-15 Kuramoto, Tokushima 770-8504, Japan.
authors.forename: Lihong
authors.initials: L
authors.lastname: Qiu
authors.forename: Kaya
authors.initials: K
authors.lastname: Yoshida
authors.forename: Bruna Rabelo
authors.initials: BR
authors.lastname: Amorim
authors.forename: Hirohiko
authors.initials: H
authors.lastname: Okamura
authors.forename: Tatsuji
authors.initials: T
authors.lastname: Haneji
mesh_terms: D016475:3T3 Cells; D000818:Animals; D004791:Enzyme Inhibitors / Q000378:metabolism*; D008387:Marine Toxins; D051379:Mice; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D016328:NF-kappa B / Q000378:metabolism; D010080:Oxazoles / Q000378:metabolism*; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction / Q000502:physiology*; D014409:Tumor Necrosis Factor-alpha / Q000235:genetics* / Q000378:metabolism
chemical_list: D004791:Enzyme Inhibitors; D008387:Marine Toxins; D020928:Mitogen-Activated Protein Kinases; D016328:NF-kappa B; D010080:Oxazoles; D019869:Phosphatidylinositol 3-Kinases; D051057:Proto-Oncogene Proteins c-akt; D012333:RNA, Messenger; D014409:Tumor Necrosis Factor-alpha; C059041:calyculin A