Overexpression of antisense phosphatase 2C affords cold resistance in hybrid Populus davidiana × Populus bolleana.

BACKGROUND: Overexpression of the abiotic and biotic stress-resistance genes of the plant signaling pathway is well known for its significant role in the regulation of plant growth and enhancement of the productivity of agricultural land under changing climatic conditions. OBJECTIVES: This research aimed to clone Populus davidiana × Populus bolleana PP2C (PdPP2C) gene and analyze its structure and function, and downregulate PdPP2C by overexpression of its antisense PdPP2C (AS-PdPP2C) gene for enhancing cold resistance in transgenic lines of hybrid P. davidiana × P. bolleana. METHODS: PdPP2C was cloned and transformed to identify its function, and its antisense was overexpressed via downregulation to increase the cold resistance in transgenic lines of hybrid P. davidiana × P. bolleana. RESULTS: Antisense inhibition of protein phosphatase 2C accelerates the cold acclimation of Poplar (P. davidiana × P. bolleana) gene in terms of antifreeze. CONCLUSION: PdPP2C was expressed in the roots, stems, and leaves of P. davidiana × P. bolleana, and the expression was higher in the leaves. The expression of PdPP2C was also significantly downregulated at low-temperature (0 °C and 4 °C) stress. The relative conductivity and malondialdehyde content of non-transgenic lines were higher than those of AS-PdPP2C lines after 2 days of cold treatment at - 1 °C. The leaves of the transgenic lines were not wilted and showed no chlorosis compared with those of the non-transgenic lines. The AS-PdPP2C transgenic lines also showed higher freezing resistance than the non-transgenic lines. AS-PdPP2C participated in the regulation of freezing resistance.

PPM1D Functions as Oncogene and is Associated with Poor Prognosis in Esophageal Squamous Cell Carcinoma.

Mounting evidence has demonstrated that PPM1D participates in the development and progression of a wide variety of tumors. However, its precise roles in esophageal squamous cell carcinoma (ESCC) remain under investigation. Here, UALCAN, an interactive web-portal to perform the expression analyses of PPM1D using TCGA gene expression data, and PPM1D high expression was exhibited in primary esophageal cancer. Further investigation revealed that PPM1D expression was obviously higher in ESCC tissues than in normal tissues (P < 0.01), which was consistent with the results from real-time qPCR and Western blotting in ESCC tissues and paired normal esophageal tissues. Besides, PPM1D expression was closely correlated with TNM staging, tumor differentiation and lymph node metastasis (P < 0.01), but not related to the patients' gender and age (P > 0.05). Notably, PPM1D expression in metastatic ESCC patients was markedly higher than that in non-metastatic ESCC patients (P < 0.01), and the ESCC patients with high PPM1D expression predicted poor prognosis. Multivariate assay demonstrated that PPM1D and lymph node metastasis were considered as independent prognostic factors for the ESCC patients. These findings suggest PPM1D plays a pivotal important role in onset and progression of ESCC, and may be a new biomarker for metastasis and prognosis of the ESCC patients.

Contribution of time delays to p53 oscillation in DNA damage response.

Although the oscillatory dynamics of the p53 network have been extensively studied, the understanding of the mechanism of delay-induced oscillations is still limited. In this paper, a comprehensive mathematical model of p53 network is studied, which contains two delayed negative feedback loops. By studying the model with and without explicit delays, the results indicate that the time delay of Mdm2 protein synthesis can well control the pulse shape but cannot induce p53 oscillation alone, while the time delay required for Wip1 protein synthesis induces a Hopf bifurcation to drive p53 oscillation. In addition, the synergy of the two delays will cause the p53 network to oscillate in advance, indicating that p53 begins the repair process earlier in the damaged cell. Furthermore, the stability and bifurcation of the model are addressed, which may highlight the role of time delay in p53 oscillations.

miR-186 downregulates protein phosphatase PPM1B in bladder cancer and mediates G1-S phase transition.

Nuclear factor-κB (NF-κB) is a core regulator in multiple tumorigenic pathways. Its activation is mediated by IκB kinase ß (IKKß). Protein phosphatase PPM1B is reported to dephosphorylate IKKß, thereby terminating IKKß-mediated NF-κB activation. However, the role of PPM1B in bladder cancer is unclear. The aim of this study was to determine the expression patterns and molecular mechanisms of PPM1B in bladder cancer. Comparative analyses were conducted in six bladder cancer cell lines, a normal urinary epithelial cell line, and adjacent non-tumorous bladder epithelia. Searches were conducted through publicly available algorithms and The Cancer Genome Atlas. HT-1376 and RT4 cells were transduced to stably overexpress PPM1B and its predicted regulator miR-186. Subsequent in vitro studies included 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide (MTT), colony formation, anchorage-independent growth ability, luciferase reporter assays, and flow cytometric cell cycle analyses. A xenograft model was established in nude mice to evaluate the effect of PPM1B in bladder tumors in vivo. The results revealed that PPM1B was frequently downregulated in bladder cancer cells at both protein and messenger RNA (mRNA) levels, whereas miR-186 was upregulated. Further analyses showed that miR-186 promoted G1-S transition by targeting PPM1B at its 3'-untranslated region (3'UTR). Conversely, ectopic expression of PPM1B significantly suppressed proliferation and tumorigenicity in bladder cancer cells in vitro and in vivo, thereby neutralizing the oncogenic effect of miR-186. This study has identified PPM1B and miR-186 as potential diagnostic markers in bladder cancer. Promotion of PPM1B and suppression of miR-186 may offer effective therapeutic strategies in the treatment of bladder cancer.