• The Roles of p21(Waf1/CIP1) and Hus1 in Generation and Transmission of Damage Signals Stimulated by Low-Dose Alpha-Particle Irradiation

    分类: 生物学 >> 生物物理学 >> 生物力学与生物流变学 提交时间: 2016-05-12

    摘要: Previously reported studies have demonstrated the involvement of p21(Waf1/CIP1) in radiation-induced bystander effects (RIBE). Mouse embryonic fibroblasts (MEFs) lacking Hus1 fail to proliferate in vitro, but inactivation of p21 allows for the continued growth of Hus1-deficient cells, indicating the close connection between p21 and Hus1 cells. In this study, wildtype MEFs, Hus1(+/+)p21(-/-) MEFs and p21(-/-)Hus1(-/-) MEFs were used in a series of radiation-induced bystander effect experiments, the roles of p21 and Hus1 in the induction and transmission of radiation-induced damage signals were investigated. Our results showed that after 5 cGy alpha particle irradiation, wild-type MEFs induced significant increases in gamma-H2AX foci and micronuclei formation in bystander cells, whereas the bystander effects were not detectable in p21(-/-)Hus1(+/+) MEFs and were restored again in p21(-/-)Hus1(-/-) MEFs. Media transfer experiments showed that p21(-/-)Hus1(+/+) MEFs were deficient in the production bystander signals, but could respond to bystander signals. We further investigated the mitogen-activated protein kinases (MAPKs) that might be involved in the bystander effects. It was found that although knocking out p21 did not affect the expression of connexin43 and its phosphorylation, it did result in inactivation of some MAPK signal pathway kinases, including JNK1/2, ERK1/2 and p38, as well as a decrease in reactive oxygen species (ROS) levels in irradiated cells. However, the activation of MAPK kinases and the ROS levels in irradiated cells were restored in the cell line by knocking out Hus1. These results suggest that p21(Waf1/CIP1) and Hus1 play crucial roles in the generation and transmission of bystander damage signals after low-dose a particle irradiation. (C) 2015 by Radiation Research

  • Comparison of Hydrazide Chemistry and Lectin Affinity Based Enrichment Methods for N-glycoproteomics

    分类: 生物学 >> 生物物理学 >> 生物物理、生物化学与分子生物学 提交时间: 2016-05-11

    摘要: Glycosylation is one of the most common and important post-translational modifications of proteins. Identification of large-scale N-linked glycoprotein is a very important aspect in glycoproteomics research. The N-glycopeptide enrichment is a key step in high-throughput identification of N-glycosylation site. Lectin enrichment and hydrazide chemistry are the two widely used N-glycopeptides enrichment methods. Each method can only enrich certain types of glycopeptides. It has been reported that the two methods are highly complementary, but few studies compared overlaps of glycosties from the two methods. In this paper, using HepG2 cells, we systematically compared the performance of hydrazide chemistry and lectins enrichment methods. The results showed that although the hydrazide method with glycopeptides enrichment efficiency of 76.7%, far higher than the 54.6% lectin enrichment method, 825 glycoprotein and 1 879 N-glycosylation sites identified with the lectin method was significantly more than 522 glycoprotein and 1 014 glycosylation sites enriched by the hydrazide method. Moreover, the two methods did not show significant complementary, together, only 853 glycoproteins and 1 959 N-glycosylation sites were identified. The overlapping results of identified N-glycosylation sites and N-glycoproteins from the two methods show that lectins enrichment method was better than hydrazide chemistry method.