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Provides evidence that arsenite can induce phosphorylation of histone H3 at serine 10 in a time- and dose-dependent manner in JB6 Cl 41 cells. Arsenite-induced phosphorylation of Akt1 at serine 473 and resulting increase in Akt1 activity.

Demonstrated that both piroxicam, a general cyclooxygenases (COX) inhibitor, and NS-398, a COX-2 selective inhibitor, effectively suppressed the activation of transcription factor activator protein 1 (AP-1) induced by ultraviolet B or 12-O-tetradecanoylphorbol-13-acetate in mouse epidermal JB6 cells. AP-1 luciferase reporter gene; Cell transformation; Rate-limiting enzymes; Assay of AP-1 activity in vivo.

Presents information on a study which determined the role of mitogen-activated protein kinases in UVB-induced phosphorylation of p53 genes at serine 20. Results; Discussion; Methodology.

Presents a study which investigated the organ-specific distribution of activator protein-1 (AP-1) in AP-1 luciferase transgenic mice during the maturation process. Materials and methods; Detection of AP-1 activity in different organs of transgenic mice; Tissue distribution AP-1 luciferase activity in skin; Discussion.

Analyzes the organ-specific distribution of activator protein-1 (AP-1) in AP-1 luciferase transgenic mice of different ages. Level of phosphorylated mitogen activated kinase in the skin; Link of AP-1 deoxyribonucleic acid binding activity to the maturation and aging process; Level of phosphorylated p38 kinase.

Ultraviolet B (UVB) induces phosphorylation of histone H3 at serine 10, and mitogen-activated protein kinases are involved in this signal transduction pathway. Here we provide evidence that Fyn kinase, a member of the Src kinase family, is involved in the UVB-induced phosphorylation of histone H3 at serine 10. UVB distinctly increased Fyn kinase activity and phosphorylation. Fyn kinase inhibitors 4-amino-5-(4-chlorophenyl)7(t-butyl)pyrazol(3,4-d)pyramide and leflunomide, an Src kinase inhibitor, suppressed both UVB-induced phosphorylation of histone H3 at serine 10 and Fyn kinase activity and phosphorylation. UVB-induced phosphorylation of histone H3 at serine 10 was blocked by either a dominant-negative mutant of Fyn (DNM-Fyn) kinase or small interfering RNA of Fyn kinase. UVB-induced phosphorylation and activities of ERKs and protein kinase B/Akt were markedly inhibited by DNMFyn kinase. However, DNM-Fyn kinase did not inhibit UVB-induced phosphorylation of p38 MAPK or c-Jun N-terminal kinases. Active Fyn kinase phosphorylated histone H3 at serine 10 in vitro, and the phosphorylated Fyn kinase could translocate into the nucleus of HaCaT cells. These results indicate that Fyn kinase plays a key role in the UVB-induced phosphorylation of histone H3 at serine 10. [ABSTRACT FROM AUTHOR]

Metastasis is a major cause of cancer-related deaths. Approximately 80% of patients with colorectal cancer develop liver metastasis and 20% develop lung metastasis. We found that at different stages of colon cancer, IFNγ secretion from peripheral blood mononuclear cells was decreased compared with healthy controls. The ribosomal S6 kinase (RSK) family of kinases has multiple cellular functions, and we examined their roles in this observed IFNγ decrease. Flow cytometry analysis of wild-type (WT) and RSK2 knockout (KO)mice revealed significantly lower levels of IFNγ in the RSK2 KO mice compared with the WT mice. Since IFNγ is a component of immunity, which contributes to protection against metastatic carcinomas, we conducted a colon cancer liver metastasis experiment. We found significantly greater metastasis in RSK2 KO mice compared with WT mice. Transcription factor T-bet can directly activate Ifnγ gene transcription. In vitro kinase assay results showed that RSK2 phosphorylated T-bet at serines 498 and 502. We show that phosphorylation of T-bet by RSK2 is required for IFNγ expression, because knockdown of RSK2 expression or overexpression of mutant T-bet reduces IFNγ mRNA expression. To verify the function of the phosphorylation sites, we overexpressed a constitutively active mutant T-bet (S498E/S502E) in bone marrow. Mutant T-bet restored the IFNγ mRNA levels and dramatically reduced the metastasis rate in these mice. Overall, these results indicate that phosphorylation of T-bet is required for the inhibition of colon cancer metastasis and growth through a positive regulation of RSK2/T-bet/IFNγ signaling. [ABSTRACT FROM AUTHOR]

Background. Recent evidence suggests that childhood obesity is increasing in children with typical development (TD) and in children with autism spectrum disorders (ASD). The associations between physical activity (PA) levels and physical fitness components have not yet been objectively examined in this population but may have clinical implications for the development of secondary health complications. Objective. The aims of this study were: (1) to compare PA and physical fitness between secondary school-aged male students with ASD and their peers with TD and (2) to assess possible interrelationships between PA and physical fitness levels in each group. Design. This was a cross-sectional study. Methods. Physical activity was recorded every 10 seconds by using accelerometry in 70 male students with (n=35) and without (n=35) ASD for up to 5 weekdays and 2 weekend days. The Brockport Physical Fitness Test was used to assess physical fitness. Results. The primary findings were: (1) participants with ASD were less physically active overall and engaged in moderate-to-vigorous PA for a lower percentage of time compared with participants with TD during weekdays; (2) participants with ASD had significantly lower scores on all physical fitness measures, except body composition; and (3) group-dependent relationships existed between physical fitness profiles and PA levels. Limitations. The study design limits causal inference from the results. Conclusion. Specific interventions for maximizing PA and physical fitness levels in secondary school-aged male students with ASD are urgently needed. [ABSTRACT FROM AUTHOR]

TRAF2 has an important function in mediating the TNF-R signaling pathway toward activation of NF-κB and JNKs. Here we reveal a novel function of TRAF2 in the epidermal growth factor (EGF) signaling pathway. Knockdown of TRAF2 blocked EGF-induced AP-1 activity and anchorage- independent cell transformation. Notably, we showed that EGF induces ribosomal S6 kinase 2 (RSK2) ubiquitination, and knocking down TRAF2 suppresses ubiquitination of RSK2 induced by EGF. We also found that TRAF2 affects RSK2 activity through RSK2 ubiquitination. RSK2 plays a critical role in AP-1 activity mediated through CREB and c-Fos, which regulates anchorage-independent cell transformation. In addition, TRAF2 is overexpressed in colon cancer and required for colon cancer development, suggesting that TRAF2 might be a potential molecular target for cancer prevention and treatment. [ABSTRACT FROM AUTHOR]

The ribosomal S6 kinase 2 (RSK2) is a member of the p90 ribosomal S6 kinase (p90RSK) family of proteins and plays a critical role in proliferation, cell cycle, and cell transformation. Here, we report that RSK2 phosphorylates caspase-8, and Thr-263 was identified as a novel caspase-8 phosphorylation site. In addition, we showed that EGF induces caspase-8 ubiquitination and degradation through the proteasome pathway, and phosphorylation of Thr-263 is associated with caspase-8 stability. Finally, RSK2 blocks Fas-induced apoptosis through its phosphorylation of caspase-8. These data provide a direct link between RSK2 and caspase-8 and identify a novel molecular mechanism for caspase-8 modulation by RSK2. [ABSTRACT FROM AUTHOR]

MST1 (mammalian STE20-like kinase 1) is a serine/threonine kinase that is cleaved and activated by caspases during apoptosis. Overexpression of MST1 induces apoptotic morphological changes such as chromatin condensation, but the mechanism is not clear. Here we show that MST1 induces apoptotic chromatin condensation through its phosphorylation of histone H2AX at Ser-139. During etoposide-induced apoptosis in Jurkat cells, the cleavage of MST1 directly corresponded with strong H2AX phosphorylation. In vitro kinase assay results showed that MST1 strongly phosphorylates histone H2AX. Western blot and kinase assay results with a mutant S139A H2AX confirmed that MST1 phosphorylates H2AX at Ser-139. Direct binding of MST1 and H2AX can be detected when co-expressed in HEK293 cells and was also confirmed by an endogenous immunoprecipitation study. When overexpressed in HeLa cells, both the MST1 full-length protein and the MST1 kinase domain (MST1-NT), but not the kinase-negative mutant (MST1- NT-KN), could induce obvious endogenous histone H2AX phosphorylation. The caspase-3 inhibitor benzyloxycarbonyl-DEVD-fluoromethyl ketone (Z-DEVD-fmk) attenuates phosphorylation of H2AX by MST1 but cannot inhibit MST1-NT-induced histone H2AX phosphorylation, indicating that cleaved MST1 is responsible for H2AX phosphorylation during apoptosis. Histone H2AX phosphorylation and DNA fragmentation were suppressed in MST1 knock-down Jurkat cells after etoposide treatment. Taken together, our data indicated that H2AX is a substrate of MST1, which functions to induce apoptotic chromatin condensation and DNA fragmentation. [ABSTRACT FROM AUTHOR]

Inactivation of the p16INK4a tumor suppressor protein is critical for the development of human cancers, including human melanoma. However, the molecular basis of the protein's inhibitory effect on cancer development is not clear. Here we investigated a possible mechanism for p16INK4a inhibition of neoplastic transformation and UV-induced skin cancer. We show that p16INK4a suppresses the activity of c-Jun N-terminal kinases (JNKs) and that it binds to the glycine-rich loop of the N-terminal domain of JNK3. Although p16INK4a does not affect the phosphorylation of JNKs, its interaction with JNK inhibits c-Jun phosphorylation induced by UV exposure. This, in turn, interferes with cell transformation promoted by the H-Ras–JNK–c-Jun–AP-1 signaling axis. [ABSTRACT FROM AUTHOR]

2-Arachidonoylglycerol (2-AG) is the most abundant endocannabinoid, and it plays a critical role in cannabinoid receptor-mediated cell signaling. Although 2-AG was shown to induce ERK activation via the cannabinoid receptor 1 (CB1), only a nonspecific CB receptor agonist and antagonist was used in those studies. Whether cannabinoid receptor 2 (CB2) is involved in 2-AG-induced ERK activation is still unclear. Moreover, whether 2-AG is involved in mediation of AP-1 activity and cell transformation is also not known. In the present study, we show that 2-AG stimulates AP-1-dependent transcriptional activity and enhances epidermal growth factor-induced cell transformation in mouse epidermal JB6 P+ Cl41 cells. Using JB6 P+ C141 cells, stably transfected with an AP-1 luciferase reporter, we found that 10 µM 2-AG induced up to a 3-fold stimulation of AP-1 transcriptional activity. The AP-1 stimulation appeared to be mediated by ERK but not JNK or p38 kinase. PD98059, a specific inhibitor of MEK1, almost completely blocked 2-AG-induced ERK phosphorylation and AP-1 activation. Using CB1/2-/- murine embryonic fibroblasts, we present the first direct evidence that both cannabinoid receptors 1 and 2 (CB1/2) are involved in 2-AG-induced ERK activation. 2-AG could not stimulate ERK phosphorylation or Fyn kinase activity in dominant negative Fyn. In addition, the Fyn inhibitor PP2 blocked 2-AG-induced Fyn kinase activity and ERK phosphorylation and activity. Small interfering RNA Fyn also suppressed 2-AG-induced ERK phosphorylation. Interestingly, 2-AG enhanced epidermal growth factor-induced AP-1 DNA binding and cell transformation. Taken together, our data provide direct evidence suggesting that 2-AG may have a novel role in cell transformation and carcinogenesis in a signaling pathway involving CB1/2 and activation of Fyn, ERKs, and AP-1. [ABSTRACT FROM AUTHOR]

The relationship between cell transformation and p38 MAP kinase, a major mitogen-activated protein (MAP) kinase pathway converting signals of various extracellular stimuli into expression of specific target genes through activation of transcription factors, still remains unclear. The aim of the present study was to investigate the role of the p38 MAP kinase pathway in epidermal growth factor (EGF)-induced cell transformation in JB6 cells. Our data show that a dominant negative mutant of p38 MAP (DN-p38) kinase inhibits EGF-promoted JB6 C141 cell transformation and that SB202190, an inhibitor of p38 MAP kinase, also inhibits JB6 C141 cell transformation in a dose-dependent manner. Moreover, our results show that DN-p38 MAP kinase inhibits the phosphorylation of EGF-stimulated activating transcription factor-2 (ATF-2) and signal transducer and activator of transcription 1 (STAT1). Additionally, DN-p38 MAP kinase inhibits EGF-induced phosphorylation of c-Myc (Thr[sup 58]/Ser[sup 62]). Gel shift assays indicate that DN-p38 MAP kinase inhibits EGF-induced activator protein-1 (AP-1) DNA binding in a dose-dependent manner. These results show that p38 MAP kinase plays a key role in the regulation of EGF-induced cell transformation in JB6 cells through regulation of phosphorylation of p38 MAP kinase and activation of its target genes in phosphorylation, c-Myc cell transformation-related genes, and AP-1 binding ability. [ABSTRACT FROM AUTHOR]

Examines the effects of Omega3 fatty acids eicosapentaenoic acid and docosahexaenoic acids (DHA) on tumorigenesis. Effects of fatty acids on activator protein activity; Use of AA concentrations to investigate the interactive effects of arachidonic acid and DHA; Suppression of JB6 cell anchorage-independent transformation by DHA.