Purification and Characterization of Laccase from Monodictys asperospera (Cooke & Massee) Ellis / 微生物学通报

A new wood-degrading fungus Monodictys asperospera(Cooke & Massee) Ellis with a high level of laccase production was chosen to study.This laccase was purified by ammonium sulfate precipitation,DEAE-cellulose and sephacryl S-300.Purification of about 8.1 fold was achieved with an overall yield of 5.7%.Its molecular weight was estimated to be about 77 kD.The optimum temperature and pH of the lac-case activity were 55?C and 6.0,respectively.Kinetic studies of the laccase showed that the Km and the Vmax for using syringaldazine as substrate was 0.163 mmol/L and 0.194 mmol/(L.min),respectively.The carbo-hydrate content was 18.14%.In addition,it was found that laccase activity was significantly inhibited by Cu2+.

Growth inhibition of human leukemia cell line U937 by all-trans retinoic acid and its mechanism / 中华血液学杂志

<p><b>OBJECTIVE</b>To study the effect of all-trans retinoic acid (ATRA) on U937 cell growth and its mechanism.</p><p><b>METHODS</b>Cell cycle was detected by flow cytometry (FCM), expressions of cell cycle associated protein and the p27 related protein were detected by Western blot. The binding of P27 and Skp2 was detected by immunoprecipitation.</p><p><b>RESULTS</b>FCM displayed that ATRA could inhibit the proliferation of U937 cells. At 72 h on 1 micromol/L ATRA treatment, 72% of the cells were arrested at G0/G1 phase. Western blot displayed that ATRA could decrease the expression of cyclin A, up-regulate the expression of p21 and p27, and down-regulate the expression of p27 related proteins Skp2. p27 could bind with Skp2 in U937 cells as detected by immunoprecipitation.</p><p><b>CONCLUSION</b>ATRA may arrest the proliferation of U937 cells through the reduction of Skp2 expression, and finally the induction of the accumulation of p27.</p>

Expression variation and significance of Skp2 and p27(kip1) during the proliferation of Jurkat cells / 中华肿瘤杂志

<p><b>OBJECTIVE</b>To investigate the expression variation and significance of Skp2 and p27(kip1) during the proliferation of lymphoma cell line Jurkat cells.</p><p><b>METHODS</b>The binding of p27(kip1) and Skp2 in Jurkat cells were detected by immunoprecipitation. Jurkat cells were treated with serum starvation and release synchronization. The expression variation and subcellular localization of p27(kip1) and Skp2 were detected by subcellular fractionation, Western blot and double immunofluorescence labelling.</p><p><b>RESULTS</b>The results of immunoprecipitation suggested that p27(kip1) and Skp2 could bind each other in Jurkat cells. During the proliferation of Jurkat cells, the protein expression of p27(kip1) decreased and intranuclear p27(kip1) decreased significantly, while the Skp2 protein increased and cytoplasmic Skp2 increased significantly.</p><p><b>CONCLUSION</b>During the proliferation of Jurkat cells, the increased cytoplasmic synthesis of Skp2 may speed up p27(kip1) degradation via the ubiquitin-proteasome pathway, then intranuclear p27(kip1) decreases significantly, leading to an increased cell cycling activity.</p>

Expression and relationship of p27(kip1) and its nuclear export factor Jab1 in lymphoma cell Jurkat / 中华血液学杂志

<p><b>OBJECTIVE</b>To investigate the expression and relationship of p27(kip1) and its nuclear export factor Jab1 during proliferation process of lymphoma cell.</p><p><b>METHODS</b>Jurkat and Raji cells were treated with serum starvation and then serum release. The protein and mRNA expression of p27(kip1), Jab1 in the cells were detected by Western blot and RT-PCR respectively. LMB were used for stimulating Jurkat cells during their proliferation process, and then the expression changes of p27(kip1) and Jab1 were detected. An eukaryotic expression plasmid(pcDNA3. 1-myc) containing Jab1 was constructed. Jurkat cell were transfected in vitro with or without pcDNA3. 1-myc-Jab1. Double immunolabelling was used to identify the localization of p27(kip1). Immunoprecipitation was used to detect the combination of p27(kip1) and Jab1.</p><p><b>RESULTS</b>The growth of Jurkat and Raji cells were blocked by serum starvation. The total protein amount of p27(kip1) increased while that of Jab1 decreased. The reverse changes were happened after serum release, but the mRNA expression of p27(kip1) has no significant change. LMB could inhibit the cell proliferation caused by serum release. The expression of p27(kip1) was up-regulated and Jab1 down-regulated when Jurkat cells were treated with LMB. After pcDNA3. 1-myc-Jab1 infected Jurkat cells for 48 h, the distribution of p27(kip1) was translocated from nucleus into cytoplasma. p27(kip1) and Jab1 could form compound in Jurkat and Raji cells detected by Immunoprecipitation.</p><p><b>CONCLUSION</b>Jab1 may influence the location and expression of p27(kip1) through integrating with p27(kip1), and then participates in regulating the growth of NHL cell through interfering with the function of p27(kip1).</p>