The Cul3–KLHL21 E3 ubiquitin ligase targets Aurora B to midzone microtubules in anaphase and is required for cytokinesis

Cul3 (Cullin3)-based E3 ubiquitin ligases recently emerged as critical regulators of mitosis. In this study, we identify two mammalian BTB (Bric-a-brac–Tramtrack–Broad complex)-Kelch proteins, KLHL21 and KLHL22, that interact with Cul3 and are required for efficient chromosome alignment. Interestingly, KLHL21 but not KLHL22 is necessary for cytokinesis and regulates translocation of the chromosomal passenger complex (CPC) from chromosomes to the spindle midzone in anaphase, similar to the previously described BTB-Kelch proteins KLHL9 and KLHL13. KLHL21 directly binds to Aurora B and mediates ubiquitination of Aurora B in vitro. In contrast to KLHL9 and KLHL13, KLHL21 localizes to midzone microtubules in anaphase and recruits Aurora B and Cul3 to this region. Together, our results suggest that different Cul3 adaptors nonredundantly regulate Aurora B during mitosis, possibly by ubiquitinating different pools of Aurora B at distinct subcellular localizations.     

The analysis of the factors influencing the development of glucocorticoid resistance in the etiopathogenesis of severe bronchial asthma

Bronchial asthma is a disease of multi - factored etiology. Current data show that multiple genes may be involved in the pathogenesis of asthma. Corticosteroids (GCS) are the most effective anti-inflammatory therapy for inflammatory disease such as bronchial asthma. There are 2 major types of GCS-resistant asthma to treatment of high doses of inhaled and oral glucocorticoids. Type I GCS-resistant asthma is cytokine-induced or acquired. Type II GCS resistance involves generalized primary cortisol resistance, which affects all tissues and is likely associated with a mutation in the GCR gene or in genes that modulate GCR function. There are clear examples of glucocorticoid gene h-GCR/NR3C1 polymorphisms that can influence responses and sensitivity to glucocorticosteroids. This article may lead to holistic the development analysis of the factors determining the progress of the glucocorticoid resistance in the severe bronchial asthma with special acknowledgement of the influence of polymorphisms of the glucocorticoid receptor gene h-GCR/NR3C1 to formation GCS resistance.     

Molecular characterization of isolated from murine adult tissues very small embryonic/epiblast like stem cells (VSELs)

Pluripotent very small embryonic/epiblast derived stem cells (VSELs) as we hypothesize are deposited at begin of gastrulation in developing tissues and play an important role as backup population of pluripotent stem cells (PSCs) for tissue committed stem cells (TCSCs). We envision that during steady state conditions these cells may be involved in tissue rejuvenation and in processes of regeneration/repair after organ injuries. Molecular analysis of adult bone marrow (BM)-derived purified VSELs revealed that they i) express pluripotent stem cells markers e.g., Oct4, Nanog, Klf-4, SSEA-1 ii) share several markers characteristic for epiblast as well as migratory primordial germ cells (PGCs), and iii) possess a unique pattern of genomic imprinting (e.g., erasure of differently methylated regions at Igf2-H19 and Rasgrf1 loci and hypermethylation at KCNQ1 and Igf2R loci). This supports that VSELs are related to epiblast-derived migrating PGC-like cells and, despite their pluripotent stem cell character, changes in the epigenetic signature of imprinted genes keep these cells quiescent in adult tissues and prevent them from teratoma formation. In contrast epigenetic changes/mutations that lead to activation of imprinted genes could potentially lead to tumor formation by these cells. Mounting evidence accumulates that perturbation of expression of imprinted genes is a common phenomenon observed in developing tumors.     

Cytoskeletal changes during cellular response of the A549 lung cancer cells to continuous cisplatin treatment

The cytoskeleton is a ubiquitous cellular structure that plays a crucial role in most processes of living cells. There are reports suggesting that this system not only reflects, but also contributes to many different processes, including cell death. In this study, we examined alterations of both MT and MF cytoskeletal systems related to cell death, which was induced in A549 cells by continuous cisplatin treatment. We observed that specific changes in these cytoskeletal proteins accompany cell death, while the others are associated with increased repair and cell survival. It seems that the predominant mode of cell death triggered by cisplatin was an apoptotic‐like pathway, but on the other hand, coincidence with some features of necrosis and autophagy was also demonstrated in our conditions.     

Immature Dengue Virus: A Veiled Pathogen?

Cells infected with dengue virus release a high proportion of immature prM-containing virions. In accordance, substantial levels of prM antibodies are found in sera of infected humans. Furthermore, it has been recently described that the rates of prM antibody responses are significantly higher in patients with secondary infection compared to those with primary infection. This suggests that immature dengue virus may play a role in disease pathogenesis. Interestingly, however, numerous functional studies have revealed that immature particles lack the ability to infect cells. In this report, we show that fully immature dengue particles become highly infectious upon interaction with prM antibodies. We demonstrate that prM antibodies facilitate efficient binding and cell entry of immature particles into Fc-receptor-expressing cells. In addition, enzymatic activity of furin is critical to render the internalized immature virus infectious. Together, these data suggest that during a secondary infection or primary infection of infants born to dengue-immune mothers, immature particles have the potential to be highly infectious and hence may contribute to the development of severe disease.     

Analysis of proton exchange kinetics with time-dependent exchange rate

Mass spectrometry is used to probe the kinetics of hydrogen–deuterium exchange in lysozyme in pH 5, 6 and 7.4. An analysis based on a Verhulst growth model is proposed and effectively applied to the kinetics of the hydrogen exchange. The data are described by a power-like function which is based on a time-dependence of the exchange rate. Experimental data ranging over many time scales is considered and accurate fits of a power-like function are obtained. Results of fittings show correlation between faster hydrogen–deuterium exchange and increase of pH. Furthermore a model is presented that discriminates between easily exchangeable hydrogens (located in close proximity to the protein surface) and those protected from the exchange (located in the protein interior). A possible interpretation of the model and its biological significance are discussed.     

Polymorphisms in methyl-group metabolism genes and risk of sporadic colorectal cancer with relation to the CpG island methylator phenotype

Background: The CpG island methylator phenotype (CIMP), together with extensive promoter methylation, is regarded as one of the mechanisms involved in colorectal carcinogenesis. The mechanisms underlying CIMP in sporadic colorectal cancer are poorly understood. Genes involved in methyl-group metabolism are likely to affect DNA methylation and thereby influence an individual's risk of CIMP. The aim of the present study was to evaluate whether polymorphisms in the genes encoding methyl-group metabolism pathway predispose to CIMP+ and/or CIMP? CRC. Methods: We examined the potential association between the polymorphisms of MTHFR 677C>T, TS 5′UTR 2R/3R, TS 3′UTR 1494del6, ΔDNMT3B ?149C>T and DNMT3B ?283T>C in a group of 46 CIMP+ CRC cases, 140 CIMP? CRC cases and 140 healthy controls. The CIMP status of the CRC cases was determined by MS-PCR in tumor tissue by a panel of five markers (CACNA1G, IGF2, NEUROG1, RUNX3 and SOCS1), which was also followed by analyzing hMLH1 methylation and BRAF V600E mutation. Results: The variant allele homozygote genotype for the ΔDNMT3B ?283T>C polymorphism was associated with a decreased risk for CIMP+ CRC (OR: 0.31, 95%CI: 0.09–0.73, p = 0.009). Individuals with TS 3R/3R had an increased risk of CIMP? CRC (OR: 2.21, 95%CI: 1.23–4.91, p = 0.01). Moreover, the carriers of 3R allele had an increased risk of CIMP? CRC (OR: 1.45, 95%CI: 1.10–2.13, p = 0.01). Conclusion: This study provides support to the hypothesis that methyl-group metabolism plays a role in the etiology of both CIMP+ and CIMP? colorectal cancers but has a different impact on a distinct molecular subgroups of colorectal cancer.