Members of the Bcl2 family of proteins are important regulators of programmed cell death pathways with individual members that can suppress (eg Bcl2, Bcl-XL) or promote (eg Bax, Bad) apoptosis. While ...the mechanism(s) of Bcl2's anti-apoptotic function is not yet clear, introduction of Bcl2 into most eukaryotic cell types will protect the recipient cell from a wide variety of stress applications that lead to cell death. There are, however, physiologic situations in which Bcl2 expression apparently fails to protect cells from apoptosis (eg negative selection of thymocytes). Further, Bcl2 expression in patient tumor samples does not consistently correlate with a worse outcome or resistance to anticancer therapies. For example, patient response and survival following chemotherapy is independent of Bcl2 expression at least for pediatric patients with ALL. These findings indicate that simple expression of Bcl2 may not be enough to functionally protect cells from apoptosis. The finding that Bcl2 is post-translationally modified by phosphorylation suggests another level of regulation of function. Recent studies have shown that agonist-activated phosphorylation of Bcl2 at serine 70 (single site phosphorylation), a site within the flexible loop domain (FLD), is required for Bcl2's full and potent anti-apoptotic function, at least in murine IL-3-dependent myeloid cell lines. Several protein kinases have now been demonstrated to be physiologic Bcl2 kinases indicating the importance of this post-translational modification. Since Bcl2 phosphorylation has been found to be a dynamic process involving both a Bcl2 kinase(s) and phosphatase(s), a mechanism exists to rapidly and reversibly regulate Bcl2's activity and affect cell viability. In addition, multisite Bcl2 phosphorylation induced by anti-mitotic drugs like paclitaxel may inhibit Bcl2 indicating the potential wide range of functional consequences that this post-translational modification may have on function. While post-translational mechanisms other than phosphorylation may also regulate Bcl2's function (eg ubiquitination), this review will focus on the regulatory role for phosphorylation and discuss its potential clinical ramifications.
To investigate the role of NLRP12 in regulating Pseudomonas aeruginosa (P. aeruginosa) keratitis.
Real-Time-PCR and Western blot were performed to measure the NLRP12 level in corneas and bone ...marrow-derived macrophages (BMDMs) of C57BL/6 (B6) mice. B6 mice received a subconjunctival injection of lentivirus expressing active NLRP12 (NLRP12-lentivirus) or Ctl-lentivirus (as control), followed by infection of P. aeruginosa. The clinical score, slit lamp and bacterial plate count of mice were evaluated. In addition, myeloperoxidase (MPO) was detected to assess the infiltration of polymorphonuclear neutrophil (PMN). Cytokine levels were measured by Real Time-PCR and ELISA. Meanwhile, the bacterial burden was also evaluated. The activation of NF-κB signaling was determined by pIκBα/IκBα levels based on Western blot and NF-κB-dependent Luciferase activity on the basis of Luciferase assays using 293T cells.
NLRP12 mRNA and protein levels were decreased in B6 corneas and BMDMs after P. aeruginosa infection. The over-expression of NLRP12 in B6 corneas significantly ameliorated the severity of corneal disease, bacterial burden, PMN infiltration and pro-inflammatory cytokine expression. In vitro analysis demonstrated that the up-regulation of NLRP12 suppressed pro-inflammatory cytokine production and enhanced bacterial clearance in RAW264.7 cells. The protein levels of pIκBα and IκBα were significantly decreased after NLRP12-lentivirus treatment compared with that of Ctl-lentivirus. NF-κB-dependent Luciferase activity was potently inhibited by NLRP12 infected with P. aeruginosa or cotransfected with the downstream signaling molecules including IKKα and IKKβ in 293T cells.
NLRP12 decreases the severity of P. aeruginosa keratitis, reduces corneal inflammation and bacterial burden through the down-regulation of the NF-κB signaling pathway.
The mammalian inactive X chromosome (Xi) condenses into a bipartite structure with two superdomains of frequent long-range contacts, separated by a hinge region. Using Hi-C in edited mouse cells with ...allelic deletions or inversions within the hinge, here we show that the conserved Dxz4 locus is necessary to maintain this bipartite structure. Dxz4 orientation controls the distribution of contacts on the Xi, as shown by a massive reversal in long-range contacts after Dxz4 inversion. Despite an increase in CTCF binding and chromatin accessibility on the Xi in Dxz4-edited cells, only minor changes in TAD structure and gene expression were detected, in accordance with multiple epigenetic mechanisms ensuring X silencing. We propose that Dxz4 represents a structural platform for frequent long-range contacts with multiple loci in a direction dictated by the orientation of its bank of CTCF motifs, which may work as a ratchet to form the distinctive bipartite structure of the condensed Xi.
It has been reported that the miR-106b similar to 25 cluster, a paralog of the miR-17 similar to 92 cluster, possesses oncogenic activities. However, the precise role of each microRNA (miRNA) in the ...miR-106b similar to 25 cluster is not yet known. In this study, we examined the function of miR-93, one of the microRNAs within the miR-106b similar to 25 cluster, in angiogenesis and tumor formation. We found that miR-93 enhanced cell survival, promoted sphere formation and augmented tumor growth. Most strikingly, when miR-93-overexpressing U87 cells were co-cultured with endothelial cells, they supported endothelial cell spreading, growth, migration and tube formation. In vivo studies revealed that miR-93-expressing cells induced blood vessel formation, allowing blood vessels to extend to tumor tissues in high densities. Angiogenesis promoted by miR-93 in return facilitated cell survival, resulting in enhanced tumor growth. We further showed that integrin- beta 8 is a target of miR-93. Higher levels of integrin- beta 8 are associated with cell death in tumor mass and in human glioblastoma. Silencing of integrin- beta 8 expression using small interfering RNA promoted cell proliferation, whereas ectopic expression of integrin- beta 8 decreased cell growth. These findings showed that miR-93 promotes tumor growth and angiogenesis by suppressing, at least in part, integrin- beta 8 expression. Our results suggest that inhibition of miR-93 function may be a feasible approach to suppress angiogenesis and tumor growth.
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•A modified coaxial electrospinning process was developed to facilitate the successful creation of medicated shellac nanofiber.•The natural resin shellac has great potential in ...targeted drug delivery.•A new family of colon-targeted nanocomposite formulations was developed.•A novel drug release mechanism for shellac systems is proposed.
Medicated shellac nanofibers providing colon-specific sustained release were fabricated using coaxial electrospinning. A solution of 7.5g shellac and 1.5g of ferulic acid (FA) in 10mL ethanol was used as the core fluid, and a mixture of ethanol and N,N-dimethylformamide (8/10 v/v) as the shell. The presence of the shell fluid was required to prevent frequent clogging of the spinneret. The diameters of the fibers (D) can be manipulated by varying the ratio of shell to core flow rates (F), according to the equation D=0.52F−0.19. Scanning electron microscopy images revealed that fibers prepared with F values of 0.1 and 0.25 had linear morphologies with smooth surfaces, but when the shell fluid flow rate was increased to 0.5 the fiber integrity was compromised. FA was found to be amorphously distributed in the fibers on the basis of X-ray diffraction and differential scanning calorimetry results. This can be attributed to good compatibility between the drug and carrier: IR spectra indicated the presence of hydrogen bonds between the two. In vitro dissolution tests demonstrated that there was minimal FA release at pH 2.0, and sustained release in a neutral dissolution medium. The latter occurred through an erosion mechanism. During the dissolution processes, the shellac fibers were gradually converted into nanoparticles as the FA was freed into solution, and ultimately completely dissolved.
Gastric cancer is a heterogeneous disease with diverse molecular and histological subtypes. We performed whole-genome sequencing in 100 tumor-normal pairs, along with DNA copy number, gene expression ...and methylation profiling, for integrative genomic analysis. We found subtype-specific genetic and epigenetic perturbations and unique mutational signatures. We identified previously known (TP53, ARID1A and CDH1) and new (MUC6, CTNNA2, GLI3, RNF43 and others) significantly mutated driver genes. Specifically, we found RHOA mutations in 14.3% of diffuse-type tumors but not in intestinal-type tumors (P < 0.001). The mutations clustered in recurrent hotspots affecting functional domains and caused defective RHOA signaling, promoting escape from anoikis in organoid cultures. The top perturbed pathways in gastric cancer included adherens junction and focal adhesion, in which RHOA and other mutated genes we identified participate as key players. These findings illustrate a multidimensional and comprehensive genomic landscape that highlights the molecular complexity of gastric cancer and provides a road map to facilitate genome-guided personalized therapy.
Blastocystis is a common anaerobic colonic protist in humans with controversial pathogenicity. Clostridium difficile (C. difficile) is the commonest cause of infectious diarrhea in healthcare ...settings. The prevalence and subtype (ST) characteristics of Blastocystis in patients with C. difficile infection (CDI) are rarely documented. Therefore, the present study was conducted to investigate the prevalence and subtype characteristics of Blastocystis in patients with suspicion of CDI in Singapore. Fecal samples were collected from 248 patients presenting with suspected CDI from a single tertiary hospital in Singapore. C. difficile was diagnosed through positive glutamate dehydrogenase (GDH) with or without toxin A/B using enzyme immunoassay methods. The prevalence and subtype genetic characteristics of Blastocystis were determined by polymerase chain reaction (PCR) amplification and analysis of the barcode region of the SSU rRNA gene. The proportion of C. difficile in patients with healthcare-associated diarrhea in this study was 44% (109/248). Among the 109 C. difficile-positive patients, 59 (54.1%, 59/109) tested positive for toxigenic C. difficile, which was considered CDI. Based on the sequence analyses of the barcode region of the SSU rRNA gene, 10.1% (25/248) of the patients were found to be Blastocystis-positive, and three subtypes were identified: ST7 (64%, 16/25), ST1 (20%, 5/25), and ST3 (16%, 4/25). Remarkably, we found five patients with Blastocystis and C. difficile coinfection, and further subtype analysis showed two with ST7, two with ST1, and one with ST3. To the best of our knowledge, this is the first study to investigate the subtype distributions of Blastocystis in patients with CDI in Singapore. We found ST7 to be the predominant subtype in diarrheal patients. The pathogenicity of ST7 has been strongly suggested in previous in vitro and mouse model experiments, further confirming its potential pathogenicity to humans.
To better understand the genetic diversity of cucurbit-infecting poleroviruses in Taiwan, a survey was conducted in 2008 and 2009 as a prelude to screening germplasm for resistance. Out of 102 ...cucurbit samples showing yellowing symptoms collected across eight counties, 29 were identified as infected by polerovirus(es) by reverse transcription polymerase chain reaction (RT-PCR) using a set of universal polerovirus primers. Sequence analysis of a 1·4-kb PCR product spanning part of the RNA-dependent RNA polymerase (RdRp) gene, the intergenic region (IR) and the complete coat protein (CP) gene of 13 of the 29 samples revealed the presence of three distinct Polerovirus species, namely Cucurbit aphid-borne yellows virus (CABYV), Melon aphid-borne yellows virus (MABYV) and Suakwa aphid-borne yellows virus (SABYV). In addition to the common strain of CABYV (CABYV-C) a recombinant strain of CABYV (CABYV-R) was identified. The recombinant strain probably arose by recombination in the IR, a recombination hot-spot of poleroviruses, between ancestors of MABYV and CABYV-C. RT-PCR protocols based on sets of specific primers were developed to distinguish between the different cucurbit-infecting polerovirus species and the two CABYV strains. These findings are discussed in relation to strategies for breeding for durable resistance against poleroviruses.
Summary
What is Known and Objective: The pathogenic mechanism of antituberculosis drug‐induced hepatotoxicity (ATDH) is thought to involve drug‐metabolizing enzymes including N‐acetyl transferase2 ...(NAT2), cytochrome P4502E1 (CYP2E1) and glutathione S‐transferase (GST) M1, T1. The associations between genetic polymorphisms of those genes and ATDH have been reported but with inconsistent results. Moreover, most studies were hospital‐based retrospective studies and not prospective. We aimed to investigate possible associations of CYP2E1, GSTM1 and GSTT1 genetic polymorphisms with ATDH using a more robust case–control study nested in a population‐based prospective antituberculosis treatment cohort.
Methods: A total of 4304 patients with smear‐positive tuberculosis (TB) who received standard short‐course chemotherapy were monitored for 6–9 months. Incidence density sampling method was adopted to select controls and 4 : 1 matched with each ATDH cases by age (±5 years), sex, treatment history, disease severity and drug dosage. The CYP2E1, GSTM1 and GSTT1 polymorphisms were genotyped using PCR–RFLP and multiplex PCR methods. Conditional logistic regression model was used to calculate odds ratio (OR) and 95% confidence interval (CI), as well as corresponding P‐values.
Results and Discussion: A total of 89 ATDH cases and 356 controls were included in this study. There was no statistically significant association between CYP2E1 RsaI c1/c1 genotype or DraI C/C genotype and ATDH (OR = 0·99, 95% CI:0·62–1·59; OR = 1·13, 95% CI: 0·40–3·20, respectively) compared with CYP2E1 RsaI c1/c2 or c2/c2 genotypes or DraI D/D genotype, or between GSTM1/GSTT1 null genotypes and ATDH (OR = 1·22, 95% CI: 0·76–1·96; OR = 0·96, 95% CI: 0·60–1·52, respectively) compared with non‐null genotypes.
What is new and Conclusion: This is the first study of the involvement of CYP2E1, GSTM1 and GSTT1 genetic polymorphisms in ATDH using a nested case–control population‐based prospective cohort design. We could not confirm positive associations of genetic polymorphisms of CYP2E1 RsaI, CYP2E1 DraI, GSTM1 null and GSTT1 null with ATDH reported by various groups, in our Chinese TB population.
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