Interleukin-6 increases rat metalloproteinase-13 gene expression through Janus kinase-2-mediated inhibition of serine/threonine phosphatase-2A |
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Authors: | de la Torre Paz Díaz-Sanjuán Teresa García-Ruiz Inmaculada Esteban Elena Canga Fernando Muñoz-Yagüe Teresa Solís-Herruzo José A |
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Institution: | Department of Medicine, Gastroenterology, Research Center, Hospital Universitario 12 de Octubre, Avd. Córdoba, 28041-Madrid, Spain. |
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Abstract: | Interleukin-6 (IL-6) increases metalloproteinase-13 (MMP-13) gene expression by increasing phosphorylated c-Jun and by inhibiting serine/threonine phosphatase-2A (PP2A) activity. We investigated the mechanisms by which IL-6 induces c-Jun phosphorylation and PP2A inactivation in Rat-1 fibroblasts. We show that IL-6 increased MMP-13 mRNA, phosphorylated c-Jun, and activator protein 1 (AP1) binding activity without increasing c-Jun-N-terminal kinase (JNK) activity. These effects did not seem to be mediated by ERK, p38 MAP kinase, phosphatidylinositol-3-kinase, calmoduline-dependent protein kinase, protein kinase C (PKC) or protein kinase A since inhibition with specific inhibitors did not abrogate these effects. IL-6 increases PP2A catalytic subunit tyrosine phosphorylation. Inhibition of the tyrosine kinase Jak2, with the specific inhibitor AG490, abrogated this effect. Likewise, this Jak2 inhibitor blocked the effects of IL-6 on c-Jun phosphorylation, AP1 binding activity and metalloproteinase-13 gene expression. We conclude that IL-6 increases MMP-13 gene expression by activation of Jak2, resulting in tyrosine phosphorylation of the catalytic subunit of PP2A, which in turn decreases PP2A activity and prolongs c-Jun phosphorylation. |
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