The p38 SAPK Pathway Regulates the Expression of the MMP-9 Collagenase via AP-1-Dependent Promoter Activation

106

Mitogen-activated protein kinases (MAPKs) regulate gene expression through transcription factors. However, the precise mechanisms in this critical signal event are largely unknown. Here, we show that the transcription factor c-Jun is activated by p38␥ MAPK, and the activated c-Jun then recruits p38␥ as a cofactor into the matrix metalloproteinase 9 (MMP9) promoter to induce its trans-activation and cell invasion. This signaling event was initiated by hyperexpressed p38␥ that led to increased c-Jun synthesis, MMP9 transcription, and MMP9-dependent invasion through p38␥ interacting with c-Jun. p38␥ requires phosphorylation and its C terminus to bind c-Jun, whereas both c-Jun and p38␥ are required for the trans-activation of MMP9. The active p38␥/c-Jun/MMP9 pathway also exists in human colon cancer, and there is a coupling of increased p38␥ and MMP9 expression in the primary tissues. These results reveal a new paradigm in which a MAPK acts both as an activator and a cofactor of a transcription factor to regulate gene expression leading to an invasive response. MAPKs3 (including extracellular signal-regulated kinases (ERKs), c-Jun N-terminal kinases (JNKs), and p38s) are critical signaling cascades that convert upstream signals into biological responses such as cell proliferation, invasion, and transformation (1). MAPKs are believed to do so by phosphorylating and activating a group of transcription factors, which through binding regulatory DNA elements lead to altered gene transcription. c-Jun is a major component of the AP-1 transcription factor downstream of MAPKs, whereas AP-1 is composed of homodimers of the Jun family or its heterodimers with another transcription factor such as c-Fos to bind the consensus DNA elements TGAg/cTCA (2). c-Jun is activated by JNK through phosphorylation at Ser-63, Ser-73, Thr-91, and Thr-93, and by ERK and p38 via increased gene expression. Activated c-Jun/ AP-1 leads to a cell type-specific biological response through integrated gene expression (1). However, the exact mechanism by which c-Jun converts a MAPK activity into a target gene expression remains mostly unknown.p38 MAPKs consist of four family members (␣, ␤, ␥, and ␦) in which p38␣ is ubiquitously present, whereas p38␥ is highly expressed in certain cancers (3). In addition to well established regulatory effects in cytokine signaling and stress response, substantial evidence suggests that the p38␣ pathway functions as a tumor suppressor (4 -8). p38␥, on the other hand, is a 43-kDa protein with an unique C-terminal motif, KETXL, that can dock with the PDZ (PSD-95/Dlg/ZO-1 homology) domain of other proteins (9, 10). In contrast to p38␣, our recent studies showed that p38␥ is induced by Ras and required for Ras transformation and invasion (11, 12), indicating its oncogenic activity. The underlying mechanisms for p38␥ involvement in Ras tumorigenesis, however, have not been established. In this report, we show that p38␥ acts both as an activator and a cofactor for c-Jun in trans-activating MMP9, a critical matrix metalloprote...

Section: P38␥ Requires Phosphorylation and C Terminus To Stimulatecontrasting

confidence: 99%

p38γ MAPK Cooperates with c-Jun in trans-Activating Matrix Metalloproteinase 9

Loesch

Zhi

Hou

et al. 2010

106

“…11). The findings of the present study also agree with a previous report (49) demonstrating that TPA-dependent activation of the matrix metalloprotease-9 is mediated via p38 activation in UMSCC and NIH3T3 cells. Interaction of AP-1 with the TF TATA-binding protein may be involved in TPA-dependent gene activation via the p38 signaling pathway as demonstrated recently by Carter et al (29).…”

Section: Binding Of C-jun To the Ap-1-a Site Of The Prx I Promoter-supporting

confidence: 93%

Phorbol Ester-dependent Activation of Peroxiredoxin I Gene Expression via a Protein Kinase C, Ras, p38 Mitogen-activated Protein Kinase Signaling Pathway

Heß

Wijayanti

Neuschäfer-Rube

et al. 2003

The antioxidant protein peroxiredoxin (Prx) I is a thioredoxin peroxidase that is involved in the regulation of proliferation and differentiation of mammalian cells. Here, it is shown that Prx I gene expression was induced transcriptionally by the phorbol ester 12-O-tetradecanoylphorbol-13-acetate (TPA) in cultured rat liver tissue macrophages and RAW264.7 monocytic cells. TPA-dependent induction of Prx I gene expression was mediated by two proximal activator protein-1 sites of the rat Prx I promoter region that were nuclear targets of c-Jun as determined by transfection studies with luciferase reporter gene constructs and electrophoretic mobility shift assays. The transcription factor Nrf2, however, was not involved in the regulation of Prx I promoter activity. Prx I gene induction by TPA was decreased by protein kinase C inhibitors and overexpressed dominant negative forms of Ras and MEKK1, but not Raf-1. The p38 MAPK inhibitor SB202190 and overexpression of dominant negative mutants of MAPK kinase 4 (MKK4), MKK6, and p38 inhibited the TPA-dependent induction of Prx I gene transcription. In contrast, inhibitors of the JNK, SP600125, and the NF-B signaling pathway, caffeic acid phenethyl ester, respectively, as well as overexpressed dominant negative MKK7 and I B, had no effect on the up-regulation of Prx I reporter gene activity by TPA. Cotransfection of wild-type p38␣ and p38␤, but not that of p38␥ and p38␦, increased Prx I promoter activity. The data indicate that a protein kinase C, Ras, MEKK1, p38 MAPK signaling pathway plays a major role for the transcriptional up-regulation of Prx I gene expression.

“…AP1 motifs have been shown to be a converging site for several signal transduction pathways including ERK/MAP kinase, protein kinase C, and c-Jun N-terminal kinase pathways (22)(23)(24). In this study, we used TPA as a tool to explore the regulation of BCSG1 expression in breast cancer cells and we demonstrate that BCSG1 transcription was activated by TPA.…”

Section: Discussionmentioning

confidence: 90%

Blockade of AP1 Transactivation Abrogates the Abnormal Expression of Breast Cancer-specific Gene 1 in Breast Cancer Cells

Lü

Zhang

Gupta

et al. 2002

Breast cancer-specific gene 1 (BCSG1) is not expressed in normal breast tissue but is highly expressed in the vast majority of invasive and metastatic breast carcinomas. When over-expressed, BCSG1 significantly stimulates the proliferation and invasion of breast cancer cells. The accumulated evidence suggests that the aberrant expression of BCSG1 in breast carcinomas is caused by transcriptional activation of the BCSG1 gene. However, the transcription factors that activate BCSG1 transcription have not been identified. In this study, we extensively investigated the role of AP1 in BCSG1 expression in breast cancer cells. We demonstrate that there are two closely located AP1 binding sites residing in the first intron of the BCSG1 gene. Mutation of either AP1 motif on the BCSG1 promoter constructs markedly reduces the promoter activity. We further show that 12-O-tetradecanoylphorbol-13-acetate (TPA) increases BCSG1 mRNA expression and up-regulates BCSG1 promoter activity through the intronic AP1 sites. The effect of TPA on BCSG1 transcription is also demonstrated under in vivo conditions in intact cells by using chromatin immunoprecipitation assays that show the TPA-induced binding of c-Jun to the chromatin region encompassing the intronic AP1 sites. Finally, to examine the direct effect of AP1 transactivation on BCSG1 expression, we established stable cell lines of T47D that express the dominant negative mutant of c-Jun, TAM67. RT-PCR and Western blot analyses demonstrated that levels of BCSG1 mRNA and protein in TAM67 transfectants were drastically reduced as compared with mocktransfected cells. Furthermore, inhibition of BCSG1 expression by blocking AP1 transactivation produced a similar repressive effect on cell growth as that by expressing BCSG1 antisense mRNA. We show that the anchorage-independent growth of T47D cells expressing either TAM67 or BCSG1 antisense mRNA is significantly inhibited. Taken together, we provide strong evidence that AP1 plays an overriding role in the transcription of the BCSG1 gene and that blockade of AP1 transactivation down-regulates BCSG1 expression and suppresses tumor phenotype.Previous studies conducted by differential DNA sequencing and in situ hybridization have identified BCSG1 1 (1), also referred to as synuclein ␥ (2) or persyn (3), as a breast cancerspecific gene because of its distinct expression pattern in breast tissues. BCSG1 is not expressed in normal breast tissue or tissues with benign breast diseases but is highly expressed in the vast majority of stage III/IV breast carcinomas (1, 4). BCSG1 expression in advanced breast carcinomas is not merely adventitious but plays a positive role in the process of invasion and metastasis. It has been demonstrated that exogenous expression of BCSG1 in breast cancer cells leads to a significant increase in cell motility and cell proliferation in cell culture (5, 6), as well as a profound augmentation of metastasis in nude mice (5). Thus far, BCSG1 gene mutations or amplifications have not been found by examination of breast carc...