Heat shock induces HuR-dependent MKP-1 posttranslational regulation through the p38 MAPK signaling cascade.

Previous studies demonstrated that phosphatases play a pivotal role in modulating inflammation-associated signal transduction, particularly in the context of heat shock, where Mitogen-Activated Protein Kinase Phosphatase-1 (MKP-1) appears to have a central role. Recently, Human Antigen R (HuR) has also been identified as a factor that enhances stress-response protein MKP-1 levels. Consequently, we have directed our interest towards elucidating the mechanisms by which heat shock induces MKP-1 mRNA stabilization, dependent on HuR via the p38 MAPK Signaling Cascade. In this study, we subjected Mouse Embryonic Fibroblast (Mef) cells to heat shock treatment, resulting in a potent stabilization MKP-1 mRNA. The RNA-binding protein HuR, known to influence mRNA, was observed to bind to the MKP-1 AU-rich 3 ´untranslated region. Transfection of p38 wild-type Mef cells with a flag-HuR plasmid resulted in a significant increase in MKP-1 mRNA stability. Interestingly, transfection of the siRNA for HuR into Mef cells resulted in diminished MKP-1 mRNA stability following heat shock, inhibition of p38 MAPK activity effectively curtailed heat shock-mediated MKP-1 mRNA stability. Immunofluorescence analyses further revealed that the translocation of HuR was contingent on p38 MAPK Signaling Cascade. Collectively, these findings underscore the regulatory role of heat shock in MKP-1 gene expression at posttranscriptional levels. The mechanisms underlying the observed increased MKP-1 mRNA stability are shown to be partially dependent on HuR through the p38 MAPK Signaling Cascade.

[Determination of 23 organochlorine pesticides in soil and sediment by gas chromatography coupled with dual columns and dual electron capture detectors].

Gas chromatography (GC) coupled with dual columns and dual electron capture detectors (ECD) was established to determine 23 organochlorine pesticides in 5 soil and 5 sediment samples. Microwave assisted extraction and solid phase extraction with a Florisil column and sulfur cleanup with copper powder were used in sample pre-processing. Chromatographic analysis was performed on DB-XLB and DB-1701 capillary columns by internal standard method. This method showed good extraction efficiency, high sensitivity and good reproducibility. In the same linear range of 0.005 - 0.5 mg/L of 23 pesticides, the correlation coefficients were higher than 0.997. The average spiked recoveries were 50% - 119% with the relative standard deviations (RSDs) of 0.9% - 16.1% (n = 6) in 5 soil samples, and were 52% - 120% with RSDs of 0.3% - 28.4% ( n = 6) in 5 sediment samples, respectively. The detection limits were 0.000 05 -0.000 5 mg/kg. The results indicate that this method is suitable for the determination of the 23 organochlorine pesticides in soil and sediment samples.