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1. chinaXiv:201605.01403 [pdf]

Profiling and Relative Quantitation of Phosphoinositides by Multiple Precursor Ion Scanning Based on Phosphate Methylation and Isotopic Labeling

Cai, Tanxi; Shu, Qingbo; Liu, Peibin; Niu, Lili; Guo, Xiaojing; Yang, Fuquan; Cai, Tanxi; Shu, Qingbo; Liu, Peibin; Niu, Lili; Guo, Xiaojing; Yang, Fuquan; Cai, Tanxi; Shu, Qingbo; Hou, JunJie; Liu, Charles C.
Subjects: Biology >> Biophysics

Phosphoinositides, the phosphorylated derivatives of phosphatidylinositol (PtdIns), are key regulators of many fundamental biological processes, including cell growth, proliferation, and motility. Here, we present a novel method for rapid, sensitive, and simultaneous profiling of phosphatidylinositol trisphosphate (PtdInsP(3)), phosphatidylinositol bisphosphate (PtdInsP(2)), and phosphatidylinositol phosphate (PtdInsP) of different fatty acid compositions. This method is based on a technique called charged diacylglycerol fragment ion-specific multiple precursor ion scanning (DAG(+)-specific MPIS), coupled with prior phosphate methylation. Using DAG(+)-specific MPIS, we were able to identify 32 PtdIns, 28 PtdInsP, 30 PtdInsP(2), and 3 PtdInsP(3) molecular species from bovine brain extracts or prostatic cancer cell lines in an efficient and time-saving manner. Our analysis revealed a large range of fatty acyl compositions in phosphoinositides not obtained previously from mammalian samples. We also developed a method that involves isotopic labeling of endogenous phosphoinositides with deuterated diazomethane (CD2N2) for quantitation of phosphoinositides. CD2N2 was generated in situ through acid-catalyzed H/D exchange and methanolysis of trimethylsilyl diazomethane (TMS-diazomethane). Phosphoinositides, extracted from a PC3 prostatic cancer cell line, were labeled either with CH2N2 or CD2N2 and mixed in known proportions for DAG(+)-specific MPIS-based mass spectrometry (MS) analysis. The results indicate that isotopic labeling is capable of providing accurate quantitation of PtdInsP(3), PtdInsP(2), and PtdInsP with adequate linearity as well as high reproducibility with an average coefficient variation of 18.9%. More importantly, this new methods excluded the need for multiple phosphoinositide internal standards. DAG(+)-specific MPIS and isotopic labeling based MS analysis of phosphoinositides offers unique advantages over existing approaches and presents a powerful tool for research of phosphoinositide metabolism.

submitted time 2016-05-12 Hits677Downloads412 Comment 0

2. chinaXiv:201605.01392 [pdf]

Proteomic Comparison and MRM-Based Comparative Analysis of Metabolites Reveal Metabolic Shift in Human Prostate Cancer Cell Lines

Shu, Qingbo; Cai, Tanxi; Chen, Xiulan; Xue, Peng; Zhu, Nali; Xie, Zhensheng; Wei, Shasha; Niu, Lili; Yang, Fuquan; Shu, Qingbo; Cai, Tanxi; Chen, Xiulan; Xue, Peng; Zhu, Nali; Xie, Zhensheng; Wei, Shasha; Niu, Lili; Yang, Fuquan; Shu, Qingbo; Zhang, Qing
Subjects: Biology >> Biophysics

One of the major challenges in prostate cancer therapy remains the development of effective treatments for castration-resistant prostate cancer (CRPC), as the underlying mechanisms for its progression remain elusive. Previous studies showed that androgen receptor (AR) is crucially involved in regulation of metabolism in prostate cancer (PCa) cells throughout the transition from early stage, androgen-sensitive PCa to androgen-independent CRPC. AR achieves such metabolic rewiring directively either via its transcriptional activity or via interactions with AMP-activated protein kinase (AMPK). However, due to the heterogeneous expression and activity status of AR in PCa cells, it remains a challenge to investigate the links between AR status and metabolic alterations. To this end, we compared the proteomes of three pairs of androgen-sensitive (AS) and androgen-independent (AI) PCa cell lines, namely, PC3-AR(+)/PC3, 22Rv1/Du145, and LNCaP/C42B, using an iTRAQ labeling approach. Our results revealed that most of the differentially expressed proteins between each pair function in metabolism, indicating a metabolic shift between AS and AT cells, as further validated by multiple reaction monitoring (MRM)-based quantification of nucleotides and relative comparison of fatty acids between these cell lines. Furthermore, increased adenylate kinase isoenzyme 1 (AK1) in AS relative to AT cells may result in activation of AMPK, representing a major regulatory factor involved in the observed metabolic shift in PCa cells.

submitted time 2016-05-12 Hits752Downloads439 Comment 0

3. chinaXiv:201605.00723 [pdf]

Comparative proteomics reveals abnormal binding of ATGL and dysferlin on lipid droplets from pressure overload-induced dysfunctional rat hearts

Li, Linghai; Zhang, Huina; Li, Linghai; Zhang, Huina; Wang, Jifeng; Zhang, Shuyan; Xu, Shimeng; Shu, Qingbo; Yang, Fuquan; Liu, Pingsheng; Wang, Weiyi; Hong, Yun; Zheng, Min; Xu, Shimeng; Shu, Qingbo; Li, Juanfen; Qian, Zongjie;
Subjects: Biology >> Biophysics

Excessive retention of neutral lipids in cardiac lipid droplets (LDs) is a common observation in cardiomyopathy. Thus, the systematic investigation of the cardiac LD proteome will help to dissect the underlying mechanisms linking cardiac steatosis and myocardial dysfunction. Here, after isolation of LDs from normal and dysfunctional Sprague-Dawley rat hearts, we identified 752 heart-associated LD proteins using iTRAQ quantitative proteomic method, including 451 proteins previously unreported on LDs. The most noteworthy finding was the identification of the membrane resealing protein, dysferlin. An analysis of dysferlin truncation mutants indicated that its C2 domain was responsible for its LD localization. Quantitative proteomic results further determined that 27 proteins were increased and 16 proteins were decreased in LDs from post pressure overload-induced dysfunctional hearts, compared with normal hearts. Notably, adipose triacylglycerol lipase (ATGL) was dramatically decreased and dysferlin was substantially increased on dysfunctional cardiac LDs. This study for the first time reveals the dataset of the heart LD proteome in healthy tissue and the variation of it under cardiac dysfunction. These findings highlight an association between the altered LD protein localization of dysferlin and ATGL and myocardial dysfunction.

submitted time 2016-05-05 Hits609Downloads327 Comment 0

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