Calyculin A stimulates the expression of TNF-α mRNA via phosphorylation of Akt in mouse osteoblastic MC3T3-E1 cells

Lihong Qiu, Kaya Yoshida, Bruna Rabelo Amorim, Hirohiko Okamura, Tatsuji Haneji

Research output: Contribution to journalArticlepeer-review

6 Citations (Scopus)

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-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.

Original languageEnglish
Pages (from-to)38-44
Number of pages7
JournalMolecular and cellular endocrinology
Volume271
Issue number1-2
DOIs
Publication statusPublished - Jun 15 2007
Externally publishedYes

Keywords

  • Akt
  • Calyculin A
  • NF-κB
  • Osteoblasts
  • Protein phosphatase
  • TNF-α

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Endocrinology

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