Deamino-hydroxy-phoslactomycin B, a biosynthetic precursor of phoslactomycin, induces myeloid differentiation in HL-60 cells

During the screening for novel differentiation inducers, we found that a culture broth of Streptomyces sp. HK-803 induced myeloid differentiation of HL-60 cells. The active substance was identified as deamino-hydroxy-phoslactomycin B (HPLM) by mass spectrometry, and synthesized HPLM also induced the differentiation of HL-60 cells. HPLM showed greater inhibition of protein phosphatase 2A (PP2A) activity than phoslactomycin B (PLMB); however, PLMB and okadaic acid did not induce differentiation. Moreover, treatment with ATRA and 1α, 25(OH)₂D₃ induced retinoic acid receptor-β and 1α, 25(OH)₂ D₃ 24-hydroxylase, respectively, whereas HPLM did not, suggesting that HPLM is a novel differentiation inducer.     

Anti-leukemic activities of Dictyostelium secondary metabolites: a novel aromatic metabolite, 4-methyl-5-n-pentylbenzene-1,3-diol, isolated from Dictyostelium mucoroides suppresses cell growth in human leukemia K562 and HL-60 cells

It has previously been shown that DIF-1, a differentiation-inducing factor of the cellular slime mold Dictyostelium discoideum, possesses antitumor activities in mammalian tumor cells and that neuronal differentiation of PC12 cells can be induced with furanodictines (FDs), aminosugar analogs found in D. discoideum, or dictyoglucosamines (DGs), N-acetyl glucosamine derivatives (DG-A from D. purpureum and DG-B from D. discoideum). Thus, cellular slime molds are attractive natural resources that may provide valuable lead compounds to be utilized in the field of pharmacology and medicine. In this study, we have isolated a novel aromatic compound, 4-methyl-5-n-pentylbenzene-1,3-diol (MPBD), from fruiting bodies of the cellular slime mold D. mucoroides and assessed the in vitro antiproliferative activities of MPBD, FDs, and DGs in human leukemia K562 and HL-60 cells. MPBD at 20-80 microM dose-dependently suppressed cell growth in both K562 and HL-60 cells. While FDs at 10-80 microM did not affect cell growth, DGs at 10-40 microM dose-dependently suppressed cell growth in the cells. Although we failed to find the roles of FDs and DGs in the original organisms, MPBD at 5-20 microM was found to promote stalk cell formation in D. discoideum. The present results indicate that MPBD, DGs or their derivatives may have therapeutic potential in the treatment of cancer and confirm our expectations regarding cellular slime molds as drug resources.     

In vitro reassembly of tobacco ribulose-1,5-bisphosphate carboxylase/oxygenase from fully denatured subunits

It has been generally proved impossible to reassemble ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) from fully denatured subunits in vitro in higher plant,because large subunit of fullydenatured Rubisco is liable to precipitate when the denaturant is removed by common methods of directdilution and one-step dialysis.In our experiment,the problem of precipitation was resolved by an improvedgradual dialysis method,which gradually decreased the concentration of denaturant.However,fully denaturedRubisco subunits still could not be reassembled into holoenzyme using gradual dialysis unless chaperonin 60was added.The restored activity of reassembled Rubisco was approximately 8% of natural enzyme.Thequantity of reassembled Rubisco increased greatly when heat shock protein 70 was present in the reassemblyprocess.ATP and Mg~(2 ) were unnecessary for in vitro reassembly of Rubisco,and Mg~(2 ) inhibited the reassemblyprocess.The reassembly was weakened when ATP,Mg~(2 ) and K~ existed together in the reassembly process.     

A comparison of in vitro anticancerous activity and mechanism of ethanolic extracts from different Ganoderma genus

Five ethanolic extracts from the mycelia of Ganoderma lucidum,G.tsugae,G.oerstedii,G.subamboinense,and G.resinaceum were respectively studied on their anticancerous activities against leukemic HL-60 cell line in vitro.Results showed that all five extracts potently inhibited HL-60 proliferation.The extract from G.lucidum mycelia exerted the highest activity.Annexin V/PI bivariate flow cytometric analysis further revealed that the five extracts significantly induced early apoptosis in HL-60 cells.The results illustrate that not only G.lucidum but also other Ganoderma species can inhibit cancer cells,and their mechanisms are related to induction of apoptosis.     

Adhesion characteristics of Listeria adhesion protein (LAP)-expressing Escherichia coli to Caco-2 cells and of recombinant LAP to eukaryotic receptor Hsp60 as examined in a surface plasmon resonance sensor

Listeria adhesion protein (LAP) is an important adhesion factor in Listeria monocytogenes and interacts with its cognate receptor, mammalian heat shock protein 60 (Hsp60). The genetic identity of LAP was determined to be alcohol acetaldehyde dehydrogenase (Aad). A recombinant Escherichia coli strain expressing aad confirmed the involvement of Aad in adhesion to Caco-2 cells. Binding kinetics (ka) of recombinant LAP (rLAP) to Hsp60 was examined in a surface plasmon resonance sensor and was determined to be 5.35 x 10(8) M(-1) s(-1) and it was equivalent to the binding of anti-Hsp60 antibody (ka = 2.15 x 10(9) M(-1) s(-1)) to Hsp60. In contrast, Internalin B, an adhesion/invasion protein from L. monocytogenes, used as a control, had binding kinetics (ka) of only 2.9 x 10(6) M(-1) s(-1). The KD value of rLAP was 1.68 x 10(-8) M, which was significantly lower than Internalin B (KD = 6.5 x 10(-4) M). These results suggest that Hsp60 has significantly higher avidity for anti-Hsp60 antibody and LAP than Internalin B. In summary, LAP is identified as an alcohol acetaldehyde dehydrogenase and binding of recombinant E. coli to Caco-2 cells or rLAP to Hsp60 protein was found to be highly specific.     

肺炎嗜衣原体热休克蛋白60的研究进展

肺炎嗜衣原体是严格的细胞内寄生菌,具有独特的发育周期,是重要的呼吸道疾病病原菌,与动脉硬化等慢性心血管疾病也有关系。在肺炎嗜衣原体感染中,热休克蛋白60(Cp-HSP60)是重要的致病因素,对树突状细胞、上皮细胞、平滑肌细胞、巨噬细胞的正常功能都有影响,能够促进T细胞向Th1型分化。经过基因序列分析及氨基酸序列比对,Cp-HSP60与其他衣原体HSP60具有很高的同源性。由于HSP60高度保守,Cp-HSP60与人的HSP60在慢性疾病病理过程中是否存在交叉反应仍存在争议。疫苗是控制传染的有效措施,应用重组Cp-HSP60和表达Cp-HSP60的DNA疫苗在小鼠实验中对肺炎嗜衣原体的感染有一定的保护作用,在肺部能产生免疫记忆。     

Molecular characterisation of Cryptosporidium outbreaks in Western and South Australia

Molecular typing at the 18S rRNA and Gp60 loci was conducted on Cryptosporidium-positive stool samples from cases collected during 2007 Western Australian and South Australian outbreaks of cryptosporidiosis. Analysis of 48 Western Australian samples identified that all isolates were C. hominis and were from five different Gp60C. hominis subtype families. The IbA10G2 subtype was most common across all age groups (37/48). In South Australia, analysis of 24 outbreak samples, identified 21 C. hominis isolates, two C. parvum isolates and one sample with both C. hominis and C. parvum. All C. hominis isolates were identified as the IbA10G2 subtype.