FIGURE 9.

Pin1 modulates the stress-induced phosphorylation of NF-H through the activation of JNK. A, endogenous JNK3 was immunoprecipitated from 7-day-old primary cortical neurons either untreated (lane 1) or treated with 1 mm H₂O₂ for 1 h (lanes 2-5), and JNK activity assay was performed using c-Jun as a substrate as described under “Experimental Procedures.” The assays show phosphorylation of c-Jun at Ser-63/73. Coomassie Blue-stained gels show equal amounts of substrate in the reaction mix. The H₂O₂ stress-increased c-Jun phosphorylation is inhibited by inhibition of Pin1 by Pin1 siRNA (lane 3) and DN-Pin1 (lane 4) and JNK inhibitor SP600125 (lane 5). B, densitometry analysis of phospho-c-Jun with data obtained from A. C, JNK activity assays were performed with endogenous JNK immunoprecipitated from 7-day cortical cultures either untreated (lane1) or subjected to heat shock(44 °C for 30 min;lane2).Heatshock-induced c-Jun phosphorylation (lane 2) and inhibition of Pin1 by Pin1 siRNA (lane 3), DN-Pin1 (lane 4), and JNK inhibitor SP600125 (lane 5) inhibited heat stress-induced c-Jun phosphorylation by JNK. D, shown are the results from densitometry analysis of phospho-c-Jun with data obtained from C.