Journal Article

Dietary energy restriction inhibits ERK but not JNK or p38 activity in the epidermis of SENCAR mice

Yinghui Liu, Ellen Duysen, Ann L. Yaktine, Angela Au, Weiqun Wang and Diane F. Birt

in Carcinogenesis

Volume 22, issue 4, pages 607-612
Published in print April 2001 | ISSN: 0143-3334
Published online April 2001 | e-ISSN: 1460-2180 | DOI: http://dx.doi.org/10.1093/carcin/22.4.607
Dietary energy restriction inhibits ERK but not JNK or p38 activity in the epidermis of SENCAR mice

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Ongoing studies in our laboratory have demonstrated that dietary energy restriction (DER) inhibited 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced AP-1 transcription factor binding to DNA in the epidermis of SENCAR mice. To dissect the specific signal transduction pathways through which DER inhibits the AP-1:DNA binding, we analyzed the activities of three major MAP kinases that lead to the induction of AP-1. The changes in ERK1 and ERK2 protein expression and phosphorylation were further characterized by western blot analysis. Female SENCAR mice were pre-fed ad libitum (AL) or 40% DER diet for 8–10 weeks. The kinase activities in mouse epidermis were determined by immune complex kinase assays at 0.5, 1, 4, or 6 h following treatment with 3.2 nmol TPA to the shaved dorsal backs. ERK activity at 1 h post-TPA treatment was nearly 5-fold (P < 0.005) above basal levels in AL mice while the increase was abolished in DER mice. The TPA-induced ERK activity in AL mice was accompanied by increased phosphorylation of ERK1 and ERK2 (P < 0.05), which was abrogated in DER mice. In addition, DER mice exhibited reduced expression of total ERK1 and ERK2 and higher proportions of ERK1 and ERK2 phosphorylation in comparison with AL mice (P < 0.05). JNK activity was decreased at 1 and 6 h but increased at 4 h (P < 0.05) post-TPA treatment. TPA did not change p38 kinase activity at the time points tested. Neither JNK nor p38 activity was altered by DER. Taken together, our results indicated for the first time that DER blocked the TPA stimulation of ERK activity and suggested that the inhibition of TPA-induced AP-1 activity by DER is likely through inhibition of ERK but not JNK or p38 kinase pathway.

Keywords: AL, ad libitum; DER, dietary energy restriction; DMBA, 7,12-dimethylbenz[a]anthracene; EGF, epidermal growth factor; ERK, extracellular signal-regulated protein kinase; JNK, c-Jun N-terminal kinase; MAP, mitogen-activated protein; MBP, myelin basic protein; PKC, protein kinase C; TPA, 12–O-tetradecanoylphorbol-13-acetate; UV, ultraviolet.

Journal Article.  5112 words.  Illustrated.

Subjects: Clinical Cytogenetics and Molecular Genetics

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