Inhibition of serine proteases by functionalized sulfonamides coupled to the 1,2,5-thiadiazolidin-3-one 1,1 dioxide scaffold.

A challenge associated with drug design is the development of selective inhibitors of proteases (serine or cysteine) that exhibit the same primary substrate specificity, that is, show a preference for the same P(1) residue. While these proteases have similar active sites, nevertheless there are subtle differences in their S and S' subsites which can be exploited. We describe herein for the first time the use of functionalized sulfonamides as a design and diversity element which, when coupled to the 1,2,5-thiadiazolidin-3-one 1,1 dioxide scaffold yields potent, time-dependent inhibitors of the serine proteases human leukocyte elastase (HLE), proteinase 3 (PR 3) and cathepsin G(Cat G). Our preliminary findings suggest that (a) appending to the 1,2,5-thiadiazolidin-3-one 1,1 dioxide scaffold recognition and diversity elements that interact with both the S and S' subsites of a target protease may result in optimal enzyme selectivity and potency and, (b) functionalized sulfonamides constitute a powerful design and diversity element with low intrinsic chemical reactivity and potentially wide applicability.     

Genome-wide analysis and stress-responsive expression of CCCH zinc finger family genes in <Emphasis Type="Italic">Brassica rapa</Emphasis>

Background

Ubiquitous CCCH nucleic acid-binding motif is found in a wide-variety of organisms. CCCH genes are involved in plant developmental processes and biotic and abiotic stress responses. Brassica rapa is a vital economic crop and classical model plant of polyploidy evolution, but the functions of CCCH genes in B. rapa are unclear.

Results

In this study, 103 CCCH genes in B. rapa were identified. A comparative analysis of the chromosomal position, gene structure, domain organization and duplication event between B. rapa and Arabidopsis thaliana were performed. Results showed that CCCH genes could be divided into 18 subfamilies, and segmental duplication might mainly contribute to this family expansion. C-X_7/8-C-X₅-C₃-H was the most commonly found motif, but some novel CCCH motifs were also found, along with some loses of typical CCCH motifs widespread in other plant species. The multifarious gene structures and domain organizations implicated functional diversity of CCCH genes in B. rapa. Evidence also suggested functional redundancy in at least one subfamily due to high conservation between members. Finally, the expression profiles of subfamily-IX genes indicated that they are likely involved in various stress responses.

Conclusion

This study provides the first genome-wide characterization of the CCCH genes in B. rapa. The results suggest that B. rapa CCCH genes are likely functionally divergent, but mostly involved in plant development and stress response. These results are expected to facilitate future functional characterization of this potential RNA-binding protein family in Brassica crops.

     

Tackling the epigenome in the pluripotent stem cells

Embryonic stem cells are unique in their abilities of self-renewal and to differentiate into many, if not all, cellular lineages. Transcrip- tional regulation, epigenetic modifications and chromatin structures are the key modulators in controlling such pluripotency nature of embryonic stem cell genomes, particularly in the developmental decisions and the maintenance of cell fates. Among them, epigenetic regulation of gene expression is mediated partly by covalent modifications of core histone proteins including methylation, phosphoryla- tion and acetylation. Moreover, the chromatins in stem cell genome appear as a highly organized structure containing distinct functional domains. Recent rapid progress of new technologies enables us to take a global, unbiased and comprehensive view of the epigenetic modifications and chromatin structures that contribute to gene expression regulation and cell identity during diverse developmental stages. Here, we summarized the latest advances made by high throughput approaches in profiling epigenetic modifications and chromatin con- formations, with an emphasis on genome-wide analysis of histone modifications and their implications in pluripotency nature of embry- onic stem cells.     

Incidence of Co-Infections of HIV,Herpes Simplex Virus Type 2 and Syphilis in a Large Cohort of Men Who Have Sex with Men in Beijing,China

Background

The HIV-epidemic among MSM in China has worsened. In this key population, prevalence of HSV-2 and syphilis infection and co-infection with HIV is high.

Methods

A longitudinal study was conducted (n = 962) in Beijing, China, with three overlapping cohorts (n = 857, 757 and 760) consisting of MSM that were free from pairs of infections of concern (i.e. HIV-HSV-2, HIV-syphilis, HSV-2-syphilis) at baseline to estimate incidence of HIV, HSV-2, syphilis, and those of co-infection.

Results

The incidence of HIV, HSV-2 and syphilis in the overall cohort was 3.90 (95% CI = 2.37, 5.43), 7.87 (95% CI = 5.74, 10.00) and 6.06 (95% CI = 4.18, 7.94) cases per 100 person-years (PYs), respectively. The incidence of HIV-HSV-2, HIV-Syphilis and HSV-2-Syphilis co-infections was 0.30 (95% CI = 0.29, 0.88), 1.02 (95% CI = 0.13, 2.17) and 1.41 (95% CI: 0.04, 2.78) cases per 100 PYs, respectively, in the three sub-cohorts constructed for this study.

Conclusions

The incidence of HIV, HSV-2 and syphilis was very high and those of their co-infections were relatively high. Such co-infections have negative impacts on the HIV/STI epidemics. Prevention practices need to take such co-infections into account.     

Novel mutations in ADAMTS13 CUB domains cause abnormal pre-mRNA splicing and defective secretion of ADAMTS13

Hereditary thrombotic thrombocytopenic purpura (TTP) is an autosomal recessive thrombosis disorder, caused by loss-of-function mutations in ADAMTS13. Mutations in the CUB domains of ADAMTS13 are rare, and the exact mechanisms through which these mutations result in the development of TTP have not yet been fully elucidated. In this study, we identified two novel mutations in the CUB domains in a TTP family with an acceptor splice-site mutation (c.3569−1, G>A, intron 25) and a point missense mutation (c.3923, G>A, exon 28), resulting in a glycine to aspartic acid substitution (p.G1308D). In vitro splicing analysis revealed that the intronic mutation resulted in abnormal pre-mRNA splicing, and an in vitro expression assay revealed that the missense mutation significantly impaired ADAMTS13 secretion. Although both the patient and her brother displayed significantly reduced ADAMTS13 activity and increased levels of ultra-large VWF (ULVWF) multimers in plasma, only the female developed acute episodes of TTP. Our findings indicate the importance of the CUB domains for the protein stability and extracellular secretion of ADAMTS13.     

Studies on the Mutagenic Effect of the Chromosome by 5 MeV Electron

In this experiment, electron and y-ray-radiation were used to irradiate dry seeds of Vicia faba. Experimental results show that electron just as affective as γ-ray has significant mutagenic effect on cells. In the range of the dose, the frequency of chromosomal aberrations on the root tip cells, there are singnificantly dose-effect. But the relationship between the dose and frequency of aberrations is close to straight line and redplication. An analysis from the type of chromosomal aberrations by electron also leads to different results, in which there are more bridges and rings by electron than by γ-ray. Therefore, electron possibly have stronger two hit aberrations, and the frequency of aberration increased in proporti on with the square of dose.     

Exploration of RNA 3′ terminal locations in rat ribosome

The locations of the 3 ends of RNAs in rat ribosome were studied by a fluorescencelabeling method combined with high hydrostatic pressure and agarose electrophoresis. Under physiological conditions, only the 3 ends of 28 S and 5.8 S RNA in 80 S ribosome could be labeled with a high sensitive fluorescent probe – fluorescein 5thiosemicarbazide (FTSC), indicating that the 3 termini of 28 S and 5.8 S RNA were located on or near the surface of 80 S ribosome. The 3 terminus of 5 S RNA could be attacked by FTSC only in the case of the dissociation of the 80 S ribosome into two subunits induced by high salt concentration (1 M KCl) or at high hydrostatic pressure, showing that the 3 end of 5 S RNA was located on the interface of two subunits. However, no fluorescencelabeled 18 S RNA could be detected under all the conditions studied, suggesting that the 3 end of 18 S RNA was either located deeply inside ribosome or on the surface but protected by proteins. It was interesting to note that modifications of the 3 ends of ribosomal RNAs including oxidation with NaIO₄, reduction with KBH₄ and labeling with fluorescent probe did not destroy the translation activity of ribosome, indicating that the 3 ends of RNAs were not involved in the translation activity of ribosome.