钩端螺旋体核糖体提取物免疫保护作用的研究

作者对核糖体现有的制备方法进行了部分改进,从黄疸出血群赖型017株钩体中成功地制备了核糖体提取物。该提取物经SPA-ELISA 证实具有免疫原性,对40只受试豚鼠的保护试验结果表明,核糖体提取物对同型毒株的攻击具有明显的保护作用;结果还证明核糖体提取物能诱导机体的体液免疫反应。     

Mutation analysis of PEX7 in 60 probands with rhizomelic chondrodysplasia punctata and functional correlations of genotype with phenotype

PEX7 encodes the cytosolic receptor for the set of peroxisomal matrix enzymes targeted to the organelle by the peroxisome targeting signal 2 (PTS2). Mutations in PEX7 cause rhizomelic chondrodysplasia punctata (RCDP), a distinct peroxisome biogenesis disorder. In previous work we described three novel PEX7 mutant alleles, including one, L292X, with a high frequency due to a founder effect. We have now extended our analysis to 60 RCDP probands and identified a total of 24 PEX7 alleles, accounting for 95% of the mutant PEX7 genes in our sample. Of these, 50% are L292X, 13% are IVS9+1G>C, and the remainder are mostly private. IVS9+1G>C occurs on at least three different haplotypes and thus appears to result from recurrent mutation. The phenotypic spectrum of RCDP is broader than commonly recognized and includes minimally affected individuals at the mild end of the spectrum. To relate PEX7 genotype and phenotype, we evaluated the consequence of the disease mutation on PEX7 RNA by Northern analysis and RT/PCR. We evaluated the function of the encoded Pex7 protein (Pex7p) by expressing selected alleles in fibroblasts from RCDP patients and assaying their ability to restore import of a PTS2 marker protein. We find that residual activity of mutant Pex7p and reduced amounts of normal Pex7p are associated with milder and variant phenotypes.     

mTOR inhibitors blunt the p53 response to nucleolar stress by regulating RPL11 and MDM2 levels

Mechanistic target of rapamycin (mTOR) is a master regulator of cell growth through its ability to stimulate ribosome biogenesis and mRNA translation. In contrast, the p53 tumor suppressor negatively controls cell growth and is activated by a wide range of insults to the cell. The mTOR and p53 signaling pathways are connected by a number of different mechanisms. Chemotherapeutics that inhibit ribosome biogenesis often induce nucleolar stress and activation of p53. Here we have investigated how the p53 response to nucleolar stress is affected by simultaneous mTOR inhibition in osteosarcoma and glioma cell lines. We found that inhibitors of the mTOR pathway including rapamycin, wortmannin, and caffeine blunted the p53 response to nucleolar stress induced by actinomycin D. Synthetic inhibitors of mTOR (temsirolimus, LY294.002 and PP242) also impaired actinomycin D triggered p53 stabilization and induction of p21. Ribosomal protein (RPL11) is known to be required for p53 protein stabilization following nucleolar stress. Treatment of cells with mTOR inhibitors may lead to reduced synthesis of RPL11 and thereby destabilize p53. We found that rapamycin mimicked the effect of RPL11 depletion in terms of blunting the p53 response to nucleolar stress. However, the extent to which the levels of p53 and RPL11 were reduced by rapamycin varied between cell lines. Additional mechanisms whereby rapamycin blunts the p53 response to nucleolar stress are likely to be involved. Indeed, rapamycin increased the levels of endogenous MDM2 despite inhibition of its phosphorylation at Ser-166. Our findings may have implications for the design of combinatorial cancer treatments with mTOR pathway inhibitors.     

核糖体生物合成与肿瘤的研究进展

核糖体生物合成是细胞内重要的生物学过程，决定了细胞内蛋白质合成的速率。在肿瘤细胞旺盛的生长压力下，肿瘤中核糖体生物合成发生异常调控。有越来越多的研究表明核糖体生物合成的异常可能会促进肿瘤的发生发展，并且它也逐渐被认为是多种肿瘤的一个可行的治疗靶点。本文简要综述了核糖体生物合成过程及其在肿瘤中的异常和调控，以及药物靶向核糖体生物合成治疗肿瘤的研究进展。     

Humanized anti-VEGFR-2 ScFv-As2O3-stealth nanoparticles,an antibody conjugate with potent and selective anti-hepatocellular carcinoma activity

Low sensitivity of tumor tissue, targeting and sustained release of the drug are bottlenecks of the effect of chemotherapy on hepatocellular carcinoma. In this study, we used the ribosome display technology to screen human anti-VEGFR 2-single-chain antibody (ScFv) that could target directly to VEGFR2, and nanotechnology to prepare As2O3-nanoparticles. Then we built anti-VEGFR-2ScFv-As2O3-stealth nanoparticles using molecular coupling technology, which significantly increased anti-tumor effect while reducing toxicity. The in vivo tissue targeting distribution and anti-tumor effects of the anti-VEGFR-2 ScFv-As2O3-stealth nanoparticles were investigated. Our results showed that anti-VEGFR-2 ScFv-As2O3-stealth nanoparticles could inhibit the development of liver cancer xenograft as a targeting agent and also significantly inhibit angiogenesis.     

Molecular basis of inherited thrombocytopenias

Inherited thrombocytopenias (IT) are a heterogeneous group of diseases caused by at least 20 different genes. At present, these genes account for approximately 50% of cases, suggesting that novel genes have yet to be identified for a comprehensive understanding of platelet biogenesis defects. This review provides an update of ITs focusing on the molecular basis and potential pathogenic mechanisms affecting megakaryopoiesis and platelet production.     

From Drosophila to Humans: Reflections on the Roles of the Prolyl Isomerases and Chaperones,Cyclophilins, in Cell Function and Disease

Abstract: Despite remarkable advances in human genetics and other genetic model systems, the fruit fly, Drosophila melanogaster, remains a powerful experimental tool to probe with ease the inner workings of a myriad of biological and pathological processes, even when evolutionary forces impart apparent divergences to some of such processes. The understanding of such evolutionary differences provides mechanistic insights into genotype-phenotype correlations underpinning biological processes across metazoans. The pioneering work developed by the William Pak laboratory for the past four decades, and the work of others, epitomize the notion of how the Drosophila system breaks new fertile ground or complements research fields of high scientific and medical relevance. Among the three major genetic complementation groups produced by the Pak's laboratory and impairing distinct facets of photoreceptor neuronal function, the nina group (ninaA, …., ninaJ) selectively affects the biogenesis of G protein–coupled receptors (GPCRs), mediating the photoconversion and transduction of light stimuli. Among the nina genes identified, ninaA arguably assumes heightened significance for several reasons. First, it presents unique physiological selectivity toward the biogenesis of a subset of GPCRs, a standalone biological manifestation yet to be discerned for most mammalian homologues of NinaA. Second, NinaA belongs to a family of proteins, immunophilins, which are the primary targets for immunosuppressive drugs at the therapeutic forefront of a multitude of medical conditions. Third, NinaA closest homologue, cyclophilin B (CyPB/PPIB), is an immunophilin whose loss-of-function was found recently to cause osteogenesis imperfecta in the human. This report highlights advances made by studies on some members of immunophilins, the cyclophilins. Finally, it reexamines critically data and dogmas derived from past and recent genetic, structural, biological, and pathological studies on NinaA and few other cyclophilins that support some of such paradigms to be less than definite and advance our understanding of the roles of cyclophilins in cell function, disease, and therapeutic interventions.