Browsing by Subject "Hydrogen-Ion Concentration"

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    Precise targeting of POLR2A as a therapeutic strategy for human triple negative breast cancer
    (Springer Nature, 2019-04) Xu, Jiangsheng; Liu, Yunhua; Li, Yujing; Wang, Hai; Stewart, Samantha; Van der Jeught, Kevin; Agarwal, Pranay; Zhang, Yuntian; Liu, Sheng; Zhao, Gang; Wan, Jun; Lu, Xiongbin; He, Xiaoming; Medical and Molecular Genetics, School of Medicine
    TP53 is the most frequently mutated or deleted gene in triple negative breast cancer (TNBC). Both the loss of TP53 and the lack of targeted therapy are significantly correlated with poor clinical outcomes, making TNBC the only type of breast cancer that has no approved targeted therapies. Through in silico analysis, we identified POLR2A in the TP53-neighbouring region as a collateral vulnerability target in TNBC tumours, suggesting that its inhibition via small interfering RNA (siRNA) may be an amenable approach for TNBC targeted treatment. To enhance bioavailability and improve endo/lysosomal escape of siRNA, we designed pH-activated nanoparticles for augmented cytosolic delivery of POLR2A siRNA (siPol2). Suppression of POLR2A expression with the siPol2-laden nanoparticles leads to enhanced growth reduction of tumours characterized by hemizygous POLR2A loss. These results demonstrate the potential of the pH-responsive nanoparticle and the precise POLR2A targeted therapy in TNBC harbouring the common TP53 genomic alteration.
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    Single-Shot Top-Down Proteomics with Capillary Zone Electrophoresis-Electrospray Ionization-Tandem Mass Spectrometry for Identification of Nearly 600 Escherichia coli Proteoforms
    (American Chemical Society, 2017-11-21) Lubeckyj, Rachele A.; McCool, Elijah N.; Shen, Xiaojing; Kou, Qiang; Liu, Xiaowen; Sun, Liangliang; BioHealth Informatics, School of Informatics and Computing
    Capillary zone electrophoresis-electrospray ionization-tandem mass spectrometry (CZE-ESI-MS/MS) has been recognized as an invaluable platform for top-down proteomics. However, the scale of top-down proteomics using CZE-MS/MS is still limited due to the low loading capacity and narrow separation window of CZE. In this work, for the first time we systematically evaluated the dynamic pH junction method for focusing of intact proteins during CZE-MS. The optimized dynamic pH junction-based CZE-MS/MS approached a 1 μL loading capacity, 90 min separation window, and high peak capacity (∼280) for characterization of an Escherichia coli proteome. The results represent the largest loading capacity and the highest peak capacity of CZE for top-down characterization of complex proteomes. Single-shot CZE-MS/MS identified about 2800 proteoform-spectrum matches, nearly 600 proteoforms, and 200 proteins from the Escherichia coli proteome with spectrum-level false discovery rate (FDR) less than 1%. The number of identified proteoforms in this work is over three times higher than that in previous single-shot CZE-MS/MS studies. Truncations, N-terminal methionine excision, signal peptide removal, and some post-translational modifications including oxidation and acetylation were detected.