TY - JOUR
T1 - Calyculin A stimulates the expression of TNF-α mRNA via phosphorylation of Akt in mouse osteoblastic MC3T3-E1 cells
AU - Qiu, Lihong
AU - Yoshida, Kaya
AU - Amorim, Bruna Rabelo
AU - Okamura, Hirohiko
AU - Haneji, Tatsuji
PY - 2007/6/15
Y1 - 2007/6/15
N2 - 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-α 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-α mRNA in MC3T3-E1 cells. Pre-treatment of LY294002 and Wortmannin, inhibitors of PI3K, inhibited the calyculin A-stimulated TNF-α 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-α mRNA. BAY11-7085 and CAPE, inhibitors of NF-κB activity, did not alter the calyculin A-stimulated TNF-α mRNA expression. Indirect immunofluorescent study confirmed that NF-κB 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-α mRNA.
AB - 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-α 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-α mRNA in MC3T3-E1 cells. Pre-treatment of LY294002 and Wortmannin, inhibitors of PI3K, inhibited the calyculin A-stimulated TNF-α 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-α mRNA. BAY11-7085 and CAPE, inhibitors of NF-κB activity, did not alter the calyculin A-stimulated TNF-α mRNA expression. Indirect immunofluorescent study confirmed that NF-κB 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-α mRNA.
KW - Akt
KW - Calyculin A
KW - NF-κB
KW - Osteoblasts
KW - Protein phosphatase
KW - TNF-α
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UR - http://www.scopus.com/inward/citedby.url?scp=34249007177&partnerID=8YFLogxK
U2 - 10.1016/j.mce.2007.03.005
DO - 10.1016/j.mce.2007.03.005
M3 - Article
C2 - 17482757
AN - SCOPUS:34249007177
SN - 0303-7207
VL - 271
SP - 38
EP - 44
JO - Molecular and Cellular Endocrinology
JF - Molecular and Cellular Endocrinology
IS - 1-2
ER -