A Drosophila model of the Niemann-Pick type C lysosome storage disease: dnpc1a is required for molting and sterol homeostasis

Niemann-Pick type C (NPC) disease is a fatal autosomal-recessive neurodegenerative disorder characterized by the inappropriate accumulation of unesterified cholesterol in aberrant organelles. The disease is due to mutations in either of two genes, NPC1, which encodes a transmembrane protein related to the Hedgehog receptor Patched, and NPC2, which encodes a secreted cholesterol-binding protein. Npc1 mutant mice can be partially rescued by treatment with specific steroids. We have created a Drosophila NPC model by mutating dnpc1a, one of two Drosophila genes related to mammalian NPC1. Cells throughout the bodies of dnpc1a mutants accumulated sterol in a punctate pattern, as in individuals with NPC1 mutations. The mutants developed only to the first larval stage and were unable to molt. Molting after the normal first instar period was restored to various degrees by feeding the mutants the steroid molting hormone 20-hydroxyecdysone, or the precursors of ecdysone biosynthesis, cholesterol and 7-dehydrocholesterol. dnpc1a is normally highly expressed in the ecdysone-producing ring gland. Ring gland-specific expression of dnpc1a in otherwise mutant flies allowed development to adulthood, suggesting that the lack of ecdysone in the mutants is the cause of death. We propose that dnpc1a mutants have sterols trapped in aberrant organelles, leading to a shortage of sterol in the endoplasmic reticulum and/or mitochondria of ring gland cells, and, consequently, inadequate ecdysone synthesis.     

Discovery and structure-activity relationship of 2,6-disubstituted pyrazines, potent and selective inhibitors of protein kinase CK2

We report the discovery and structure-activity relationship of 2,6-disubstituted pyrazines, which are potent and selective CK2 inhibitors. Lead compound 1 was identified, and derivatives were prepared to develop potent inhibitory activity. As a result, we obtained compound 7, which was the smallest unit that retained potency. Then, introducing an aminoalkyl group at the 6-position of the indazole ring resulted in improved efficacy in both enzymatic and cell-based CK2 inhibition assays. Moreover, compound 13 showed selectivity against other kinases and in vivo efficacy in a rat nephritis model. These results show that 2,6-disubstituted pyrazines have potential as therapeutic agents for nephritis.     

Radiation and smoking effects on lung cancer incidence by histological types among atomic bomb survivors

While the risk of lung cancer associated separately with smoking and radiation exposure has been widely reported, it is not clear how smoking and radiation together contribute to the risk of specific lung cancer histological types. With individual smoking histories and radiation dose estimates, we characterized the joint effects of radiation and smoking on type-specific lung cancer rates among the Life Span Study cohort of Japanese atomic bomb survivors. Among 105,404 cohort subjects followed between 1958 and 1999, 1,803 first primary lung cancer incident cases were diagnosed and classified by histological type. Poisson regression methods were used to estimate excess relative risks under several interaction models. Adenocarcinoma (636 cases), squamous-cell carcinoma (330) and small-cell carcinoma (194) made up 90% of the cases with known histology. Both smoking and radiation exposure significantly increased the risk of each major lung cancer histological type. Smoking-associated excess relative risks were significantly larger for small-cell and squamous-cell carcinomas than for adenocarcinoma. The gender-averaged excess relative risks per 1 Gy of radiation (for never-smokers at age 70 after radiation exposure at age 30) were estimated as 1.49 (95% confidence interval 0.1-4.6) for small-cell carcinoma, 0.75 (0.3-1.3) for adenocarcinoma, and 0.27 (0-1.5) for squamous-cell carcinoma. Under a model allowing radiation effects to vary with levels of smoking, the nature of the joint effect of smoking and radiation showed a similar pattern for different histological types in which the radiation-associated excess relative risk tended to be larger for moderate smokers than for heavy smokers. However, in contrast to analyses of all lung cancers as a group, such complicated interactions did not describe the data significantly better than either simple additive or multiplicative interaction models for any of the type-specific analyses.     

Uptake and recovery of gold ions from electroplating wastes using eggshell membrane.

The animal byproduct, hen eggshell membrane (ESM), was evaluated for its ability to sorb gold ions (dicyanoaurate(I) and tetrachloroaurate(III)) from solutions and electroplating wastewater. The gold uptake was dependent on pH, temperature and co-ions present in the solutions, with pH 3.0 being the optimum value. The equilibrium data followed the Langmuir isotherm model with maximum capacities of 147 mg Au(I)/g dry weight and 618 mg Au(III)/g, respectively. Desorption of sorbed gold(I) with 0.1 mol/l NaOH resulted in no changes of the biosorbent gold uptake capacity through five consecutive sorption/desorption cycles. In column experiments, selective recovery of gold from electroplating wastewater containing various metal ions was noted. The affinity of metal sorption was in the order Au > Ag > Co > Cu > Pb > Ni > Zn.     

An RNA-dependent protein kinase is involved in tunicamycin-induced apoptosis and Alzheimer's disease

Various types of stress, such as disruption of calcium homeostasis, inhibition of protein glycosylation and reduction of disulfide bonds, result in accumulation of misfolded proteins in the endoplasmic reticulum (ER). The initial cellular response involves removal of such proteins by the ER, but excessive and/or long-term stress results in apoptosis. In this study, we used a randomized ribozyme library and ER stress-mediated apoptosis (tunicamycin-induced apoptosis) in SK-N-SH human neuroblastoma cells as a selective phenotype to identify factors involved in this process. We identified a double-stranded RNA-dependent protein kinase (PKR) as one of the participants in this process. The level of nuclear PKR was elevated, but the level of cytoplasmic PKR barely changed in tunicamycin-treated SK-N-SH cells. Furthermore, tunicamycin also raised levels of phosphorylated PKR in the nucleus. We also detected the accumulation of phosphorylated PKR in the nuclei of autopsied brain tissues in Alzheimer's disease. Thus, PKR might play a role in ER stress-induced apoptosis and in Alzheimer's disease.     

Temperature-gradient DNA probe chromatography of nucleic acids on nonporous supports.

Temperature-gradient DNA probe chromatography of nucleic acids on a nonporous support with a homogeneous particle size of 2.5 microns showed a higher base sequence discriminating power and a larger linear capacity than that on a porous support with a larger and less homogeneous particle size. The resolution on the nonporous support was high enough to separate samples with a single-base mismatch of the less destabilizing groups, including G-G and G-T base mismatches, even when it locates very near the end of the probe.