Doxycycline Inhibits IL-17-Stimulated MMP-9 Expression by Downregulating ERK1/2 Activation: Implications in Myogenic Differentiation

Figure 5

Doxycycline reduces MMP-9 expression by inhibiting IL-17-stimulated ERK1/2 activation in C2C12 cells. (a) MMP-9 expression in C2C12 cells determined by zymography and RT-PCR. Cells were, in the presence or absence of PD98059 (25 μM), treated with or without 50 ng/mL IL-17 for 24 h. GADPH was used as a gel loading control. Numbers represent average densitometry values over control with value 1. (b) Cells were transiently transfected with mouse MMP-9 promoter and cotransfected with DNMEK1 or CaMEK1 mutants or cotreated with PD98059 (25 μM). After the cells were treated for 24 h without or with IL-17 (50 ng/mL), luciferase activities were determined. Results are presented over control with value 1. Significant differences from the control (cells not treated with IL-17) by -test: and . (c) Expression of dominant-negative (DN) and constitutively active (Ca) mutants of MEK1 transiently transfected C2C12 cells was confirmed by their reactivity to anti-HA antibody (d) IL-17-induced ERK1/2 phosphorylation in the presence or absence of Doxy (5 or 10 μg/mL) was determined by Western blot. (e) Transactivation of pSRE-luc reporter by IL-17 in the presence or absence of Doxy.

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