Enhancer Activation by Pharmacologic Displacement of LSD1 from GFI1 Induces Differentiation in Acute Myeloid Leukemia

1. Download high-res image (244KB)
2. Download full-size image

     

Isoenzymes of hypoxanthine-guanine-phosphoribosyl transferase in a family with partial deficiency of the enzyme

The isoenzymes of hypoxanthine-guanine-phosphoribosyl transferase (HGPRT; E. C. 2.4.2.8) were studied by polyacrylamide gel disc electrophoresis in the erythrocytes of a family in which there was a partial deficiency of this X-linked enzyme. Hyperuricemic males, in whom HGPRT activity was 4% of normal, were found to have a variant enzyme which had altered kinetic and electrophoretic properties. In acrylamide gel, this variant migrated about 15% faster than the normal enzyme, and its K _m for hypoxanthine was twice that of the normal. The sister of two patients had 34% of normal activity in her erythrocytes and was thought to be a heterozygote. Electrophoresis of her hemolysate yielded profiles in which there were two zones of HGPRT activity. The more slowly migrating isoenzyme behaved electrophoretically like the normal isoenzyme. The faster-migrating isoenzyme had a mobility identical to that of the variant enzyme found in hemolysates from her hyperuricemic siblings. However, in her profile the activity of the variant enzyme was three times greater than that of the HGPRT found in the boys. This increased activity appears to be due to an interaction of the variant enzyme with the normal enzyme. Electrophoresis of a mixture of normal enzyme and the variant from a hyperuricemic male yielded a profile similar to that observed in this girl and a dramatic increase in the amount of activity in the variant zone.Aided by U.S. Public Health Service Grants No. HD04608 and GM 17702 from the National Institute of Child Health and Human Development and from the National Institute of General Medical Sciences, respectively, National Institutes of Health. Presented in part at the 1971 Annual Meeting of the Western Society for Pediatric Research, Carmel, California.     

Transformation in Group H Streptococci: Blackburn Strain Transformable Mutants

Transformable mutants of the nontransformable Blackburn strain group H streptococci have been isolated. In contrast with the wild strain, the cell surface extracts of these mutants contain the factor inactivating deoxyribonucleic acid in vitro.     

Pyrola carpatica Holub etKřísa,a new species among European Wintergreens; with remarks on the name “Pyrola intermedia”

Pyrola carpatica Holub etK?ísa is described as a new species in the seriesIncarnatae K?ísa and is compared with other representatives of the series and withPyrola rotundifolia L., a species with which it is usually confused. A more detailed note is devoted to the nomenclatural analysis of “Pyrola intermedia”, a name which has been used for the species by several authors.     

Regulation of growth of nurse nuclei in the development of egg follicles inCecidomyiidae (Diptera)

InCecidomyiidae the number of trophocytes derived from the somatic tissue of the ovary and forming nutritive chambers of egg follicles is variable. The regulation of growth of the whole nutritive chambers and of the nurse nuclei was investigated in two species of the gall midges,Mikiola fagi andBoucheella artemisiae, at two different stages of the egg follicle development during the second period of the oocyte growth. The volume of a nutritive chamber is correlated with the size of the egg follicle as a whole and is not dependent on the number of nurse nuclei it contains. The total volume of nurse nuclei at each stage under investigation was found to have a constant value which is independent of their number. It was established that the growth of the nurse nuclei takes place through endomitosis, and that at a given stage of the egg follicle development the constant value of the total volume of the nurse nuclei reflects the constancy of degree of their total polyploidy. The results obtained indicate that at the early stages of the egg follicle development the rates of growth of the nurse nuclei and of the whole nutritive chambers in the egg follicles differing with respect to the number of their nurse nuclei must be different; the greater the number of nurse nuclei in a given nutritive chamber the slower the rate of growth of the chamber and their nuclei. As a result of this differential rate of growth the volumes of the nutritive chambers and total volumes of nurse nuclei reach at a certain stage of the egg follicle development certain values common for all egg follicles, irrespective of the number of the nurse nuclei they contain. Beginning with this stage the dependence between the endomitotic activity of the nurse nuclei and the rate of growth of the whole nutritive chamber on the one hand, and the number of the nurse nuclei in the chamber on the other, evidently disappears. The available evidence supports the hypothesis that in the egg follicle ofCecidomyiidae the growth regulation of nurse nuclei and, indirectly, also of whole nutritive chambers results from developmental interrelationships between the oocyte and the nutritive chamber, and that the oocyte plays a leading role in this process. In view of a syncytial character of the nutritive chambers inCecidomyiidae and distinctly expressed asynchrony of the growth-duplication cycles of nurse nuclei belonging to a given chamber it is concluded that the control mechanism for DNA synthesis and endomitosis in nurse nuclei must possess the property of a rapid switch. Processes of the growth regulation of the nurse nuclei are discussed in connection with the role of the nutritive chamber in production of RNA and its supply to the growing oocyte. It is suggested that in the egg follicles ofCecidomyiidae there exists a complex interrelationship between the control mechanism for DNA synthesis and endomitosis in the nurse nuclei and the synthetic processes regulated by the supply of the growing oocyte with RNA produced by the nuclei of the nutritive chamber.     

Timber stacks: potential ecological traps for an endangered saproxylic beetle,the Rosalia longicorn <Emphasis Type="Italic">Rosalia alpina</Emphasis>

Ecological traps are serious, anthropogenic threats to animal populations. However, in certain cases it is difficult to determine whether they really act in the expected manner. This applies to the harmful effects of beech timber stacked in forests on the endangered saproxylic beetle Rosalia longicorn Rosalia alpina, which have been mentioned in numerous scientific articles, conservation action plans and similar publications. The aim of this paper is to determine whether beech timber stacks meet the criteria of an ecological trap for the Rosalia longicorn. Two basic criteria of such a trap are analysed: the attractiveness of timber stacks and the impossibility of complete larval development. The results show that beech timber stacks are highly attractive to Rosalia longicorn imagines. Moreover, the time during which the timber is stacked is shown to be significantly shorter than the species’ larval development period. These results suggest that timber stacks can be treated as operative ecological traps for the Rosalia longicorn, even though the extent of their influence on the demographic parameters of this beetle’s population has not been estimated. Forest management practices, i.e. increasing amounts and shifts in timing of wood storage, could intensify this threat.     

Targetting of the N‐terminal domain of the human papillomavirus type 16 E6 oncoprotein with monomeric scFvs blocks the E6‐mediated degradation of cellular p53

The E6 protein of cancer‐associated human papillomavirus type 16 (HPV16) binds to cellular p53 and promotes its degradation through the ubiquitin pathway. In an attempt to identify the regions of E6 that could be targetted for functional inhibition, we generated monoclonal antibodies to the HPV16 E6 oncoprotein (16E6) and analysed their effect on E6‐mediated p53 in vitro degradation. The isolated antibodies recognize the 16E6 oncoprotein expressed in the CaSki carcinoma cell line and strongly inhibit the proteolysis of p53 in vitro by binding specifically to a region of 10 residues located at the N‐terminal end of 16E6. The variable regions of these antibodies were cloned and expressed in E. coli as single chain Fvs (scFvs). Purified scFvs were present in monomeric form and totally abolished 16E6‐mediated p53 degradation by preventing the formation of E6/p53 protein complexes. Our results demonstrate that monovalent binding of scFvs to the N‐terminal end of 16E6 abrogates the biological mechanisms leading to the degradation of p53, and they suggest that this region of 16E6 may be a useful in vivo target for blocking the oncogenic activity of HPV16 E6 protein. Copyright © 1999 John Wiley & Sons, Ltd.     

Human interleukin‐23 receptor antagonists derived from an albumin‐binding domain scaffold inhibit IL‐23‐dependent ex vivo expansion of IL‐17‐producing T‐cells

Engineered combinatorial libraries derived from small protein scaffolds represent a powerful tool for generating novel binders with high affinity, required specificity and designed inhibitory function. This work was aimed to generate a collection of recombinant binders of human interleukin‐23 receptor (IL‐23R), which is a key element of proinflammatory IL‐23‐mediated signaling. A library of variants derived from the three‐helix bundle scaffold of the albumin‐binding domain (ABD) of streptococcal protein G and ribosome display were used to select for high‐affinity binders of recombinant extracellular IL‐23R. A collection of 34 IL‐23R‐binding proteins (called REX binders), corresponding to 18 different sequence variants, was used to identify a group of ligands that inhibited binding of the recombinant p19 subunit of IL‐23, or the biologically active human IL‐23 cytokine, to the recombinant IL‐23R or soluble IL‐23R‐IgG chimera. The strongest competitors for IL‐23R binding in ELISA were confirmed to recognize human IL‐23R‐IgG in surface plasmon resonance experiments, estimating the binding affinity in the sub‐ to nanomolar range. We further demonstrated that several REX variants bind to human leukemic cell lines K‐562, THP‐1 and Jurkat, and this binding correlated with IL‐23R cell‐surface expression. The REX125, REX009 and REX128 variants competed with the p19 protein for binding to THP‐1 cells. Moreover, the presence of REX125, REX009 and REX115 variants significantly inhibited the IL‐23‐driven expansion of IL‐17‐producing primary human CD4⁺ T‐cells. Thus, we conclude that unique IL‐23R antagonists derived from the ABD scaffold were generated that might be useful in designing novel anti‐inflammatory biologicals. Proteins 2014; 82:975–989. © 2013 The Authors. Proteins: Structure, Function, and Bioinformatics Published by Wiley Periodicals, Inc.     

Common variants of xeroderma pigmentosum genes and prostate cancer risk

The genetic basis of prostate cancer (PC) is complex and appears to involve multiple susceptibility genes. A number of studies have evaluated a possible correlation between several NER gene polymorphisms and PC risk, but most of them evaluated only single SNPs among XP genes and the results remain inconsistent. Out of 94 SNPs located in seven XP genes (XPA–XPG) a total of 15 SNPs were assayed in 720 unselected patients with PC and compared to 1121 healthy adults. An increased risk of disease was associated with the XPD SNP, rs1799793 (Asp312Asn) AG genotype (OR = 2.60; p < 0.001) and with the AA genotype (OR = 531; p < 0.0001) compared to the control population. Haplotype analysis of XPD revealed one protective haplotype and four associated with an increased disease risk, which showed that the A allele (XPD rs1799793) appeared to drive the main effect on promoting prostate cancer risk. Polymorphism in XPD gene appears to be associated with the risk of prostate cancer.