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. 2016 Mar 16;291(20):10747–10758. doi: 10.1074/jbc.M116.722272

FIGURE 5.

FIGURE 5.

pro-NGF stimulates p38 MAPK signaling in hepatocytes leading to caspase-3 activation. A, stimulation of Huh7 cells with 5 ng/ml pro-NGF for 3 h induced p38 MAPK phosphorylation. Left, immunoblot. Right, quantification. Values are means ± S.D., n = 4. **, p < 0.01 for pro-NGF versus C. B, cells were treated with 5 ng/ml pro-NGF for 16 h in the absence and presence of 1 μm of the p38 MAPK inhibitor SB203580 (SB), which reduced caspase-3 cleavage induced by pro-NGF. Left, immunoblot. Right, quantification. Values are mean ± S.E., n = 4. ***, p < 0.001 for pro-NGF versus C, and for pro-NGF + SB203580 (SB) versus pro-NGF. C, cells were transfected for 24 h with plasmids encoding dominant negative (DN) constructs for p38 MAPK and stimulated further with 5 ng/ml pro-NGF. Caspase-3 cleavage was inhibited by the DN constructs. D, cells transfected with DN-MKK6 were stimulated with 5 ng/ml pro-NGF. Upper panel, immunoblot. Lower panel, quantification. Values are mean ± S.E., n = 4. *, p < 0.05 for pro-NGF versus C and for DN-MKK6 + pro-NGF versus pro-NGF. E, cells were transfected with LDLR promoter and stimulated with 5 ng/ml pro-NGF in the absence or presence of 1 μm SB203580, and luciferase activity was measured. SB203580 counteracted the increase in LDLR gene activity induced by pro-NGF. Values are mean ± S.E., n = 4. **, p < 0.01 for pro-NGF versus C, and for pro-NGF + SB203580 versus pro-NGF.