WNT-5A induces a proinflammatory transformation in mouse microglia. (A, B) iNOS, COX-2 and TNFα were detected by immunoblotting in lysates from mouse primary microglia after WNT-5A stimulation (ctrl, 300 ng/ml, 6 hours). (B’) shows TNFα levels in the supernatant of primary microglia under ctrl conditions and upon WNT-5A stimulation (ctrl, 300 ng/ml, 24 hours; n = 4). At least three experiments are summarized in the bar graphs. Data are normalized to ctrl. Error bars give s.e.m. (C) Microglial proliferation was assessed by an MTT assay monitoring mitochondrial activity, which is proportional to cell number [see Additional file 1: Figure S5]. Stimulation with WNT-5A (300 ng/ml, 24 hours) increased MTT, which was blocked by PTX (100 ng/ml, overnight) or the MEK1/2 (10 μM) inhibitor, SL327. (D). Experiments were done in triplicate and data from three independent experiments are shown. *, P < 0.01; ***, P < 0.001: Error bars show s.e.m.. (E) Cell tracker (red)-stained primary microglia were seeded on top of a collagen matrix in 35 mm glass bottom dishes. One day after ctrl or 300 ng/ml WNT-5A stimulation, invasion was observed by confocal microscopy and Z-stacking using a Zeiss LSM710 microscope and subsequent analysis with the Bitplane Imaris software. The size of the collagen cube shown is 1,000 (Z) x 1,400 (Y) x 1,400 (X) μm. Three invasion experiments in the absence and presence of the MEK1/2 inhibitor SL327 were quantified. Data are presented in a bar graph (F). *, P < 0.05; error bars show s.e.m.. (G) cDNA of ctrl stimulated (−) and WNT-5A stimulated (+) primary microglia was analyzed by QPCR for expression of inflammatory genes. At least three independent experiments are summarized. Gene expression is normalized to the housekeeping gene GAPDH and expressed as arbitrary units (2-Δct). *, P < 0.05; **, P < 0.01. COX-2, cyclooxygenase 2; iNOS, inducible nitric oxide synthase; MTT, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide; n, number; s.e.m., standard error of the mean.