Identification of a hydrogen peroxide-induced PP1-JNK1-Sp1 signaling pathway for gene regulation

Abstract

Oxidative stress often results in changes in gene expression through the regulation of transcription factors. In this study, we examine how Sp1 phosphorylation is regulated by H(2)O(2) in a human alveolar epithelial cell line (HAE). Treatment of HAE cells with H(2)O(2) increases phosphorylation of Sp1 and activates JNK. To establish a relationship between JNK and Sp1, we show that JNK activator anisomycin increases Sp1 phosphorylation, and JNK inhibitors as well as dominant-negative JNK1 attenuate H(2)O(2)-induced Sp1 phosphorylation. Additionally, JNK1 directly phosphorylates Sp1 in vitro, reducing Sp1 binding to DNA. These results demonstrate the role of JNK in H(2)O(2)-induced Sp1 phosphorylation. Because H(2)O(2) inhibits Ser/Thr protein phosphatase-1 (PP1), we examined the role of PP1 in the regulation of JNK. Similar to H(2)O(2), inhibition of PP1 induces phosphorylation of Sp1 and activation of JNK in HAE cells. Inhibition of JNK activity using either inhibitors or dominant-negative mutant JNK1 suppresses PP1 inhibition-induced Sp1 phosphorylation. Furthermore, PP1 directly inactivates JNK1 in vitro. These data suggest that 1) H(2)O(2) increases the phosphorylation level of Sp1, 2) Sp1 is a target of the JNK pathway, 3) PP1 regulates JNK activation, and 4) the "PP1-JNK" pathway plays a role in H(2)O(2)-induced Sp1 phosphorylation in lung epithelial cells.

A Novel RhoA/ROCK-CPI-17-MEF2C Signaling Pathway Regulates Vascular Smooth Muscle Cell Gene Expression

“…3H). Previous studies in lung epithelial cells have shown that calyculin A can activate JNK signaling to induce c-Jun phosphorylation (26). This appears to be consistent in VSMCs, as phosphorylation of c-Jun by calyculin A treatment is attenuated by pre-treatment with the JNK inhibitor, SP600125 (Fig.…”

Thiazolidinediones Mimic Glucose Starvation in Facilitating Sp1 Degradation through the Up-Regulation of β-Transducin Repeat-Containing Protein

“…5A). Although JNK and ERK1/2 have been reported to regulate Sp1 transcriptional activity through phosphorylation (Benasciutti et al, 2004;Bonello and Khachigian, 2004;Chu and Ferro, 2006), the involvement of individual kinases in modulating Sp1 degradation remains unclear. To shed light on this issue, the effect of OSU-CG12 and glucose starvation on the phosphorylation status of various kinases was determined by Western blot analysis.…”

Nuclear Factor-κB Is a Critical Mediator of Ste20-Like Proline-/Alanine-Rich Kinase Regulation in Intestinal Inflammation

“…This possibility is supported by the results of previous studies that demonstrated such an interaction in IL-6 and P-selectin promoters. 46,47 The reduced levels of Sp1 binding with TNF-␣ stimulation could also be attributable to TNF-␣-induced Sp1 phosphorylation ( Figure 7B) because Sp1 phosphorylation could reduce Sp1 binding 48 and dephosphorylation of Sp1 has been suggested to enhance Sp1 DNA binding activity. 49 In DSS-treated mice, we found that DSS does not alter overall nuclear levels of Sp1, similar studies showed that TNF-␣ did not change Sp1 expression 30 but increased NF-B (p65) expression.…”