Synthesis of N-isobutylnoroxymorphone from naltrexone by a selective cyclopropane ring opening reaction

Selective ring opening reaction of the N-cyclopropylmethyl group in naltrexone (1d) was effected in the presence of platinum (IV) oxide and hydrobromic acid under a hydrogen atmosphere at rt to selectively afford N-isobutyl derivative 10. The binding affinity of N-i-Bu derivative 10 for opioid receptors was 11-17 times less than that of the corresponding N-CPM compound, naltrexone (1d). However, compound 10 showed dose-dependent analgesic effects. Contrary to expectations based on previous structure-activity relationship studies for a series of N-substituted naltrexone derivatives that compound 10 would be an opioid antagonist, 10 showed dose-dependent analgesia in the mouse acetic acid writhing test (ED(50): 5.05 mg/kg, sc), indicating it was an opioid agonist. This finding may have a great influence on the drug design of opioid agonists.     

Conformational significance of EH21A1-A4, phenolic derivatives of geldanamycin, for Hsp90 inhibitory activity

Hsp90 is an attractive chemotherapeutic target because it is essential to maturation of multiple oncogenes. We describe the conformational significance of EH21A1-A4, phenolic derivatives of geldanamycin isolated from Streptomyces sp. Their native free structures are similar to the active form of geldanamycin bound to Hsp90 protein. Their conformational character is a probable reason for their high-affinity binding. Lack of toxic benzoquinone in EH21A1-A4 also adds to their potential as lead compounds for anti-tumor drugs.     

Potent antagonists of the CCR2b receptor. Part 3: SAR of the (R)-3-aminopyrrolidine series

SAR studies were conducted around lead compound 1 using high-throughput parallel solution and solid phase synthesis. Our lead optimization efforts led to the identification of several CCR2b antagonists with potent activity in both binding and functional assays [Compound 71 CCR2b Binding IC(50) 3.2 nM; MCP-1-Induced Chemotaxis IC(50) 0.83 nM; Ca(2+) Flux IC(50) 7.5 nM].     

Intersubunit linker length as a modifier of protein stability: crystal structures and thermostability of mutant TRAP

The ability of proteins to self-assemble into complex, functional nanoscale structures is expected to become of significant use in the manufacture of artificial nanodevices with a wide range of novel applications. The bacterial protein TRAP has potential uses as a nanoscale component as it is ring-shaped, with a central, modifiable cavity. Furthermore, it can be engineered to make a ring of 12-fold symmetry, which is advantageous for packing into two-dimensional arrays. The 12mer form of TRAP is made by linking multiple subunits together on the same polypeptide, but the usefulness of the 12mers described to date is limited by their poor stability. Here we show that, by altering the length of the peptide linker between subunits, the thermostability can be significantly improved. Since the subunit interfaces of the different 12mers are essentially identical, stabilization arises from the reduction of strain in the linkers. Such a simple method of controlling the stability of modular proteins may have wide applications, and demonstrates the lack of absolute correlation between interactions observable by crystallography and the internal energy of a complex.     

AINTEGUMENTA homolog expression in Gnetum (gymnosperms) and implications for the evolution of ovulate axes in seed plants

SUMMARY The expression of GpANTL1 , a homolog of AINTEGUMENTA ( ANT ) found in the gymnosperm Gnetum parvifolium , was analyzed by RT-PCR and in situ hybridization. GpANTL1 was expressed in the leaf primordia, root tips, and young ovules. In the ovulate axis, expression was detected as four distinct rings around the outer, middle, and inner envelope primordia as well as around the nucellar tip. This pattern of expression is similar to that of ANT in Arabidopsis thaliana . A comparison of the expression of GpANTL1 with that of PtANTL1 in the conifer Pinus thunbergii suggests that the integrated expression of PtANTL1 may have been caused by congenital fusion of the integument, ovuliferous scale, and bract.     

Preservation of hematopoietic stem and progenitor cells from umbilical cord blood stored in a surface derivatized with polymer nanosegments

Tissue culture flasks were prepared with immobilized amphiphilic nanosegments of Pluronic F68 and F127, polyethylene oxide (PEO)-polypropylene oxide (PPO)-PEO triblock copolymers, on their surfaces. These so-called "Pluronic-immobilized flasks" were used for the preservation of hematopoietic stem and progenitor cells from umbilical cord blood. The expression ratio of surface markers (CD34) on hematopoietic stem and progenitor cells stored in Pluronic-immobilized flasks was significantly higher than that in polystyrene tissue culture flasks or commercially available bioinert flasks (i.e., low cell-binding cultureware). This was due to the presence of flexible brushlike segments of Pluronic on the Pluronic-immobilized flask. A good correlation was found between the number of CD34+ cells and the ratio of viable CD34+ cells from cord blood in several flasks after five days of storage. Therefore, the high number of CD34+ cells was thought to have originated from the high viability of these cells stored in Pluronic-immobilized flasks. It was found that there was an optimal surface concentration of Pluronic on the Pluronic-immobilized flask surfaces for the preservation (high number and survival) of these stem and progenitor cells. The foregoing results were attributable to the high density of Pluronic nanosegments on the flask surface, limiting the movement of these flexible segments.     

Vertebrate WRNIP1 and BLM are required for efficient maintenance of genome stability

Bloom syndrome (BS) is rare autosomal recessive disorder associated with chromosomal instability. The gene responsible for BS, BLM, encodes a protein belonging to the RecQ helicase family. Disruptions of the SGS1 gene of Saccharomyces cerevisiae, which encodes the RecQ helicase homologue in the budding yeast, causes accelerated aging, and this phenotype is enhanced by the disruption of MGS1, the budding yeast homologue for WRNIP1. To examine the functional relationship between RecQ and WRNIP1 in vertebrate cells, we generated and characterized wrnip1/blm cells derived from the chicken B-lymphocyte line DT40. wrnip1/blm cells showed an additive elevation of sister chromatid exchange (SCE), suggesting that both genes independently contribute to the suppression of excess SCE formation. The double mutants were more sensitive to DNA damage from camptothecin (CPT), but not to damage from methyl methanesulfonate, than either single mutant. This result suggests that WRNIP1 and BLM function independently to repair DNA or induce tolerance to the lesions induced by CPT.     

Identification of IL-18 and Th17 cells in salivary glands of patients with Sjögren's syndrome, and amplification of IL-17-mediated secretion of inflammatory cytokines from salivary gland cells by IL-18

IL-18 is a proinflammatory cytokine and plays an important pathogenic role in inflammatory and autoimmune disorders. IL-17 is also a proinflammatory cytokine and IL-17-secreting Th17 cells are involved in autoimmunity. However, the pathological roles of IL-18 and Th17 cells in Sj?gren's syndrome (SS) remain to be elucidated. This study showed that the expression of IL-18 was detected in acinar cells, intraducts, and CD68(+) macrophages in salivary glands of SS patients, but not in those of healthy subjects or patients with chronic graft-vs-host disease, by immunohistochemistry, and immunoblot analysis revealed that 24-kDa precursor form of IL-18 (proIL-18) and 18-kDa mature IL-18 were detected in SS salivary glands. The majority of the infiltrating cells in the salivary glands of SS patients were CD4(+) T cells, and CD8(+) T cells were infiltrated to a lesser extent. The predominant expression of IL-17 was found in infiltrating CD4(+) T cells, whereas a small number of infiltrating CD8(+) T cells expressed IL-17. Human salivary gland HSY and acinar AZA3 cells constitutively expressed proIL-18 and caspase-1, and a calcium ionophore A23187 induced the secretion of IL-18 from the cells. HSY and AZA3 cells expressed IL-18R and IL-17R on the cell surface, and IL-18 amplified the secretion of IL-6 and IL-8 that were induced by low amounts of IL-17. Primary salivary gland cells from normal subjects partially confirmed these findings. These results suggest that IL-18 and Th17 cells detected in the salivary glands in SS patients are associated with the pathogenesis of SS in the salivary glands.     

Copper, zinc-superoxide dismutase enhances the mutagenicity in Salmonella typhimurium induced by 2-amino-6-methyldipyrido[1,2-a:3',2'-d]imidazole

The mutagenicities of various carcinogens induced by liver microsomes are increased in the presence of liver cytosol in rodents. It still remains, however, to be clarified which factor or factors in the cytosol enhance(s) the microsome-mediated mutagenicities. In the present study, we sought to identify the enhancing factor in liver cytosol prepared from rats using the microsome-mediated Salmonella mutagenicity induced by 2-amino-6-methyldipyrido [1,2-a:3',2'-d] imidazole (Glu-P-1). By a series of chromatographic steps, we purified a 16-kDa protein on SDS-PAGE from the cytosol of rat livers. Partial amino acid sequences of this protein revealed that the 16-kDa protein was copper, zinc-superoxide dismutase (CuZn-SOD). The purified CuZn-SOD enhanced the microsome-mediated mutagenicities of several heterocyclic amines and aromatic amines. Furthermore, bovine and human CuZn-SOD also enhanced the microsome-mediated mutagenicity of Glu-P-1. The CuZn-SOD caused an increase in the mutagenicity of N-hydroxylated Glu-P-1 formed from Glu-P-1 by the microsomes, although CuZn-SOD did not affect either the formation or the stability of the N-hydroxylated derivative. These findings suggest that the enhancing cytosol factor for the mutagenicity of Glu-P-1 is CuZn-SOD, which stimulates the mutagenicity of N-hydroxylated Glu-P-1 without changing its metabolism.