M45 inhibits TLR- and IL-1R-mediated NF-κB but not p38 activation.

<p>(A) NIH-3T3 cells were transduced with retroviral vectors expressing M45 or GFP. Two days after transduction cells were stimulated with the TLR4 agonist LPS (10 µg/ml), the TLR2 agonist LTA-SA (10 µg/ml), or IL-1β (20 ng/ml). IκBα levels were determined by immunoblotting. (B) NIH-3T3 cells were transduced with an M45-expressing or an empty retroviral vector. 30 min after stimulation with IL-1β (10 ng/ml) cells were fixed, and subcellular localization of the NF-κB p65 subunit was analyzed by immunofluorescence. (C) NIH-3T3 cells expressing an NF-κB-dependent secreted alkaline phosphatase (SEAP) reporter were transduced with retroviral vectors expressing M45 or GFP and stimulated 78 h later with the TLR2 agonist Pam₃CSK₄ (Pam.,1 µg/ml), the TLR4 agonist LPS (0.1 µg/ml), or IL-1β (5 ng/ml). SEAP activity in the supernatant was quantified 15 h after stimulation and is shown as fold induction of SEAP activity of stimulated cells compared to non-stimulated cells (mean ± SD) (D) NIH-3T3 cells transduced with retroviral vectors expressing M45 or GFP were stimulated with IL-1β (20 ng/ml, 15 min) or TNFα (10 ng/ml, 5 min). Phosphorylated and total p38 in cell lysates was detected by immunoblotting.