Taxchinin A, with a 11(15→1)-abeo-taxane skeleton, is a major, but inactive taxoid contained in leaves of Taxus chinensis. In our design of dual-functional antitumor abeo-taxane derivatives, two fragments from antitumor agents with different molecular targets (the N-acyl-3′-phenylisoserine side chain from the antimitotic agent paclitaxel and an α,β-unsaturated carbonyl system from NF-κB inhibitors) were incorporated into the scaffold of taxchinin A. The resulting compounds displayed broad inhibitory effects against proliferation of tumor cell lines, with notable selectivity towards colon cancer, melanoma and renal cancer, when evaluated in the NCI-60 human tumor cell line screening panel. Based on the NCI-60 assay data, structure-activity relationship (SAR) correlations were elucidated. Mechanistic studies indicated that this new compound type can both destabilize microtubules and inhibit NF-κB activation, thereby inducing tumor cell apoptosis. This first report of the dual-functional taxoid-core compounds thus provides new opportunities for future drug development based on natural taxoid scaffolds.
RNA surveillance plays an important role in posttranscriptional regulation. Seminal work in this field has largely focused on yeast as a model system, whereas exploration of RNA surveillance in mammals is only recently begun. The increased transcriptional complexity of mammalian systems provides a wider array of targets for RNA surveillance, and, while many questions remain unanswered, emerging data suggest the nuclear RNA surveillance machinery exhibits increased complexity as well. We have used a small interfering RNA in mouse N2A cells to target the homolog of a yeast protein that functions in RNA surveillance (Mtr4p). We used high-throughput sequencing of polyadenylated RNAs (PA-seq) to quantify the effects of the mMtr4 knockdown (KD) on RNA surveillance. We demonstrate that overall abundance of polyadenylated protein coding mRNAs is not affected, but several targets of RNA surveillance predicted from work in yeast accumulate as adenylated RNAs in the mMtr4KD. microRNAs are an added layer of transcriptional complexity not found in yeast. After Drosha cleavage separates the pre-miRNA from the microRNA's primary transcript, the byproducts of that transcript are generally thought to be degraded. We have identified the 5′ leading segments of pri-miRNAs as novel targets of mMtr4 dependent RNA surveillance.
Genetic approaches have identified numerous loci associated with coronary heart disease (CHD). The molecular mechanisms underlying CHD gene-disease associations, however, remain unclear. We hypothesized that genetic variants with both strong and subtle effects drive gene subnetworks that in turn affect CHD.
Approach and Results
We surveyed CHD-associated molecular interactions by constructing coexpression networks using whole blood gene expression profiles from 188 CHD cases and 188 age- and sex-matched controls. 24 coexpression modules were identified including one case-specific and one control-specific differential module (DM). The DMs were enriched for genes involved in B-cell activation, immune response, and ion transport. By integrating the DMs with altered gene expression associated SNPs (eSNPs) and with results of GWAS of CHD and its risk factors, the control-specific DM was implicated as CHD-causal based on its significant enrichment for both CHD and lipid eSNPs. This causal DM was further integrated with tissue-specific Bayesian networks and protein-protein interaction networks to identify regulatory key driver (KD) genes. Multi-tissue KDs (SPIB and TNFRSF13C) and tissue-specific KDs (e.g. EBF1) were identified.
Our network-driven integrative analysis not only identified CHD-related genes, but also defined network structure that sheds light on the molecular interactions of genes associated with CHD risk.
Gene expression; coronary heart disease; systems biology; coexpression network
Improving yield is a major objective for cotton breeding schemes, and lint yield and its three component traits (boll number, boll weight and lint percentage) are complex traits controlled by multiple genes and various environments. Association mapping was performed to detect markers associated with these four traits using 651 simple sequence repeats (SSRs). A mixed linear model including epistasis and environmental interaction was used to screen the loci associated with these four yield traits by 323 accessions of Gossypium hirsutum L. evaluated in nine different environments. 251 significant loci were detected to be associated with lint yield and its three components, including 69 loci with individual effects and all involved in epistasis interactions. These significant loci explain ∼ 62.05% of the phenotypic variance (ranging from 49.06% ∼ 72.29% for these four traits). It was indicated by high contribution of environmental interaction to the phenotypic variance for lint yield and boll numbers, that genetic effects of SSR loci were susceptible to environment factors. Shared loci were also observed among these four traits, which may be used for simultaneous improvement in cotton breeding for yield traits. Furthermore, consistent and elite loci were screened with −Log10 (P-value) >8.0 based on predicted effects of loci detected in different environments. There was one locus and 6 pairs of epistasis for lint yield, 4 loci and 10 epistasis for boll number, 15 loci and 2 epistasis for boll weight, and 2 loci and 5 epistasis for lint percentage, respectively. These results provided insights into the genetic basis of lint yield and its components and may be useful for marker-assisted breeding to improve cotton production.
Reactivation of hepatitis B virus (HBV) can occur in lymphoma patients infected with HBV when they receive chemotherapy or immunotherapy. Prophylactic administration of lamivudine (LAM) reduces the morbidity and mortality associated with HBV reactivation. However, what defines HBV reactivation and the optimal duration of treatment with LAM have not yet been clearly established. HBV reactivation may occur due to the cessation of prophylactic LAM, although re-treatment with nucleoside analogs may sometimes result in hepatitis B surface antigen (HBsAg) seroconversion, which is a satisfactory endpoint for the management of HBV infection. We report a case of HBV reactivation in a 68-year-old HBsAg-positive patient who received rituximab-based immunochemotherapy for follicular lymphoma. HBV reactivation developed following cessation of prophylactic LAM therapy. The patient subsequently received treatment with entecavir (ETV), which led to a rapid and sustained suppression of HBV replication and HBsAg seroconversion. We also appraised the literature concerning HBV reactivation and the role of ETV in the management of HBV reactivation in lymphoma patients. A total of 28 cases of HBV reactivation have been reported as having been treated with ETV during or after immunosuppressive chemotherapy in lymphoma patients. We conclude that ETV is an efficacious and safe treatment for HBV reactivation following LAM cessation in lymphoma patients treated with rituximab-based immunochemotherapy.
Hepatitis B surface antigen; Seroconversion; Non-Hodgkin’s lymphoma; Rituximab; Entecavir
C-Raf is a member of the Ras-Raf-MEK-ERK mitogen-activated protein kinase (MAPK) signaling pathway that plays key roles in diverse physiological processes and is upregulated in many human cancers. C-Raf activation involves binding to Ras, increased phosphorylation and interactions with co-factors. Here, we describe a Ras-independent in vivo pathway for C-Raf activation by its downstream target MEK. Using 32P-metabolic labeling and 2D-phosphopeptide mapping experiments, we show that MEK increases C-Raf phosphorylation by up-to 10-fold. This increase was associated with C-Raf kinase activation, matching the activity seen with growth factor stimulation. Consequently, coexpression of wildtype C-Raf and MEK was sufficient for full and constitutive activation of ERK. Notably, the ability of MEK to activate C-Raf was completely Ras independent, since mutants impaired in Ras binding that are irresponsive to growth factors or Ras were fully activated by MEK. The ability of MEK to activate C-Raf was only partially dependent on MEK kinase activity but required MEK binding to C-Raf, suggesting that the binding results in a conformational change that increases C-Raf susceptibility to phosphorylation and activation or in the stabilization of the phosphorylated-active form. These findings propose a novel Ras-independent mechanism for activating C-Raf and the MAPK pathway without the need for mutations in the pathway. This mechanism could be of significance in pathological conditions or cancers overexpressing C-Raf and MEK or in conditions where C-Raf-MEK interaction is enhanced due to the downregulation of RKIP and MST2.
Raf; Ras; MEK; ERK; MAPK; phosphorylation
The genetics of complex disease produce alterations in the molecular interactions of cellular pathways whose collective effect may become clear through the organized structure of molecular networks. To characterize molecular systems associated with late-onset Alzheimer’s disease (LOAD), we constructed gene regulatory networks in 1647 post-mortem brain tissues from LOAD patients and non-demented subjects, and demonstrate that LOAD reconfigures specific portions of the molecular interaction structure. Through an integrative network-based approach, we rank-ordered these network structures for relevance to LOAD pathology, highlighting an immune and microglia-specific module dominated by genes involved in pathogen phagocytosis, containing TYROBP as a key regulator and up-regulated in LOAD. Mouse microglia cells over-expressing intact or truncated TYROBP revealed expression changes that significantly overlapped the human brain TYROBP network. Thus the causal network structure is a useful predictor of response to gene perturbations and presents a novel framework to test models of disease mechanisms underlying LOAD.
Although rituximab in the combination of CHOP chemotherapy has been widely used as the standard treatment for several kinds of B-cell non-Hodgkin lymphoma (B-NHL), a great number of B-NHL patients treated with this immunotherapy still develop primary and secondary resistance. Recently Bruton’s tyrosine kinase (Btk) inhibitor ibrutinib showed promising therapeutic effect in relapsed/refractory CLL and B-cell NHL, which provided essential alternatives for these patients.
The proliferation and apoptosis induction of tumor cells were measured by cell viability assay and Annexin-V staining. Western Blotting analysis and real-time PCR were used to detect the expression level of target proteins and chemokines production.
We demonstrated that ibrutinib inhibited the proliferation and induced apoptosis of GCB-DLBCL cell lines through suppression of BCR signaling pathway and activation of caspase-3. Furthermore, the chemokines CCL3 and CCL4 production from tumor cells were also found to be attenuated by ibrutinib treatment. But different cell lines exhibited distinct sensitivity after ibrutinib treatment. Interestingly, the decreasing level of p-ERK after ibrutinib treatment, but not the basal expression level of Btk, correlated with different drug sensitivity.
Ibrutinib could be a potentially useful therapy for GCB-DLBCL and the decreasing level of p-ERK could become a useful biomarker to predict related therapeutic response.
Germinal center B cell-like diffuse large B cell lymphoma; Bruton’s tyrosine kinase; BCR; Apoptosis
Multiple myeloma (MM) is characterized by the malignant expansion of differentiated plasma cells. Although many chemotherapeutic agents display cytotoxic activity toward MM cells, patients inevitably succumb to their disease because the tumor cells become resistant to the anticancer drugs. The cancer stem cell hypothesis postulates that a small subpopulation of chemotherapy-resistant cancer cells is responsible for propagation of the tumor. Herein we report that efflux of the pluripotent stem cell dye CDy1 identifies a subpopulation in MM cell lines characterized by increased expression of P-glycoprotein, a member of the ABC (ATP-binding cassette) superfamily of transporters encoded by ABCB1. We also demonstrate that ABCB1-overexpressing MM cells are resistant to the second-generation proteasome inhibitor carfilzomib that recently received accelerated approval for the treatment of therapy-refractive MM by the U.S. Food and Drug Administration. Moreover, increased resistance to carfilzomib in sensitive MM cells following drug selection was associated with upregulation of ABCB1 cell-surface expression which correlated with increased transporter activity as measured by CDy1 efflux. We further show that chemosensitization of MM cells to carfilzomib could be achieved in vitro by cotreatment with vismodegib, a hedgehog pathway antagonist which is currently in MM clinical trials. CDy1 efflux may therefore be a useful assay to determine whether high expression of ABCB1 is predictive of poor clinical responses in MM patients treated with carfilzomib. Our data also suggest that inclusion of vismodegib might be a potential strategy to reverse ABCB1-mediated drug resistance should it occur.
CDy1; ABCB1; multiple myeloma; carfilzomib; vismodegib; ASPM; KIF14; TMPO
Reactive nitrogen species (RNS), in particular nitric oxide (NO), are toxic to bacteria, and bacteria have mechanisms to allow growth despite this stress. Understanding how bacteria interact with NO is essential to understanding bacterial physiology in many habitats, including pathogenesis; however, many targets of NO and enzymes involved in NO resistance remain uncharacterized. We performed for the first time a metabolomic screen on NO-treated and -untreated bacteria to define broadly the effects of NO on bacterial physiology, as well as to identify the function of NnrS, a previously uncharacterized enzyme involved in defense against NO. We found many known and novel targets of NO. We also found that iron-sulfur cluster enzymes were preferentially inhibited in a strain lacking NnrS due to the formation of iron-NO complexes. We then demonstrated that NnrS is particularly important for resistance to nitrosative stress under anaerobic conditions. Our data thus reveal the breadth of the toxic effects of NO on metabolism and identify the function of an important enzyme in alleviating this stress.
The tachykininergic neurotransmitters have been proved to be involved in the inflammatory progress and chronic pain in series of disease. The present study was undertaken to evaluate the levels of substance P (SP) and its receptors NK-1 receptor (NK-1R) in both serum and synovial tissues of hip joint from patients with different stages of DDH, and to detect the possible correlation of serum SP levels with pain sensation and dysfunction of the hip joint.
SP levels in serum and synovial tissues from patients with DDH and DDH combined with osteoarthritis (DDH&OA) group were compared through immunohistochemistry (IHC), ELISA, and 2-step acetic acid extraction method respectively. Expression of NK-1R in synovial tissues was compared through IHC, quantitive Real-Time PCR (QRT-PCR) and Western-Blot. The severities of pain sensation and the functional activities of hip joint were assessed by Visual analogue scale (VAS) and Harris hip score (HHS). Correlations of serum SP levels with VAS, HHS and erythrocyte sedimentation rate (ESR) were evaluated respectively in these groups.
Significantly elevated serum SP levels were detected in group of DDH and DDH&OA compared to that in normal group. IHC, QRT-PCR as well as tissue Elisa showed that SP levels in synovial tissue of DDH&OA group is stronger than that in DDH group. Serum SP levels in each group have no gender differences. The enhanced SP levels in synovial tissue mainly came from the segregation of peripheral nerve endings. Serum SP correlated with VAS and HHS in patients with DDH&OA (Male + Female). Serum SP correlated with HHS in patients with DDH (Male). Serum SP levels also correlated with erythrocyte sedimentation rate (ESR) in patients with DDH&OA (Male + Female). Up-regulated expression of NK-1R was also observed in synovial tissue of patients with DDH&OA compared to patients with DDH, through western-blot, IHC, and QRT-PCR.
These findings indicated that the increasing SP levels in serum and synovial tissues, observed from patients with DDH to patients with DDH&OA, might associate with the loss of function and chronic pain sensation in hip joint. SP along with its receptors NK-1R might be involved in the progression of DDH into DDH&OA. In the future, inhibitors of SP as well as NK-1R may represent a novel pharmacotherapy target for pain relieving, inflammation alleviating and joint degeneration delaying for patients with DDH.
Substance P; DDH; Synovium; NK-1 receptor; Chronic pain; Osteoarthritis
Rituximab in the combination of CHOP chemotherapy has been widely used as the standard treatment for several kinds of B-cell non-Hodgkin lymphoma (B-NHL). Inactivation of phosphorylation of STAT3 plays an essential role in rituximab-induced anti-proliferative activity in B-cell lymphoma. However, the relationship between STAT3 genetic polymorphisms and clinical response to standard frontline treatment with rituximab has not been well illustrated yet.
In this study we analyzed the STAT3 polymorphisms and prognosis of 166 diffuse large B-cell lymphoma (DLBCL) patients who were treated with rituximab from 2007 to 2010. Determination of the STAT3 polymorphisms of rs2293152 from genomic DNA was achieved by Sanger chain termination sequencing.
We did not observe obvious correlation between patients’ disease features and STAT3 polymorphisms, but patients with homozygous genotypes at rs2293162 showed a trend of higher CR rate than those with the heterozygous genotype, especially in non-GCB subgroup (p = 0.011). Furthermore, homozygous genotypes GG and CC also showed advantages of long-term survival compared with heterozygous genotype patients (p = 0.022).
These results suggest that STAT3 polymorphisms could be a suitable biomarker related to clinical outcome of DLBCL patients treated with rituximab.
Diffuse large B-cell lymphoma; STAT3; Single nucleotide polymorphism; Rituximab
To identify new candidate therapeutic targets for Glioblastoma multiforme (GBM), we combined functional genetics and GBM network modeling to identify kinases required for the growth of patient-derived brain tumor initiating cells (BTICs), but which are dispensable to proliferating human neural stem cells (NSCs). This approach yielded BUB1B/BUBR1, a critical mitotic spindle checkpoint player, as the top scoring GBM-lethal kinase. Knockdown of BUB1B inhibited expansion of BTIC isolates, both in vitro and in vivo, without affecting proliferation of NSCs or astrocytes. Mechanistic studies revealed that BUB1B’s GLEBs domain activity is required to suppress lethal kinetochore-microtubule (KT-MT) attachment defects in GBM isolates and genetically transformed cells with altered sister KT dynamics, which likely favor KT-MT instability. These results indicate that GBM tumors have added requirement for BUB1B to suppress lethal consequences of altered KT function. They further suggest that sister KT measurements may predict cancer-specific sensitivity to BUB1B inhibition and perhaps other mitotic targets that affect KT-MT stability.
Human papillomavirus type 58 (HPV58) is relatively prevalent in China and other Asian countries. In this study, the HPV58 genome in cervical lesions was decoded from five grade 2 or 3 cervical intraepithelial neoplasia lesion (CIN2/3) samples and five cervical cancer tissues using rolling-circle amplification of total cell DNA and deep sequencing and verified by whole-genome cloning and sequencing. HPV58 isolates from China feature a total of 52 nucleotide substitutions (0.66%) from the reference HPV58 sequence, which appear mainly in two regions, with 12 from nucleotides (nt) 3430 to 4136 covering the E2/E4/E5 open reading frames (ORFs) and 13 from nt 4621 to 5540 covering the L2 ORF; these could be grouped as HPV58 Chinese Zhejiang-1, -2, and -3 (CNZJ-1, -2, and -3) according to their sequence similarities and restriction enzyme digestion. Phylogenetically, CNZJ-3 is similar to the reference HPV58 sublineage A1 sequence. The other two are close to sublineage A2. Analysis of cervical lesion-derived RNA revealed abundant HPV58 early transcripts spliced at the E6 and E1/E2 ORFs, where two 5′ splice sites at nt 232 and nt 898 and two 3′ splice sites at nt 510 and nt 3355 can be identified. Thus, our study represents the first genome-wide analysis of HPV58 and its expression in cervical lesions.
Quorum sensing (QS) is a process by which individual bacteria are able to communicate with one another, thereby enabling the population as a whole to coordinate gene regulation and subsequent phenotypic outcomes. Communication is accomplished through production and detection of small molecules in the extracellular milieu. In many bacteria, particularly Vibrio species, multiple QS systems result in multiple signals, as well as cross talk between systems. In this study, we identify two QS systems in the halophilic enteric pathogen Vibrio fluvialis: one acyl-homoserine lactone (AHL) based and one CAI-1/AI-2 based. We show that a LuxI homolog, VfqI, primarily produces 3-oxo-C10-HSL, which is sensed by a LuxR homolog, VfqR. VfqR-AHL is required to activate vfqI expression and autorepress vfqR expression. In addition, we have shown that similar to that in V. cholerae and V. harveyi, V. fluvialis produces CAI-1 and AI-2 signal molecules to activate the expression of a V. cholerae HapR homolog through LuxO. Although VfqR-AHL does not regulate hapR expression, HapR can repress vfqR transcription. Furthermore, we found that QS in V. fluvialis positively regulates production of two potential virulence factors, an extracellular protease and hemolysin. QS also affects cytotoxic activity against epithelial tissue cultures. These data suggest that V. fluvialis integrates QS regulatory pathways to play important physiological roles in pathogenesis.
Epithelial-mesenchymal transition (EMT) promotes cancer invasion and metastasis, but the integrative mechanisms that coordinate these processes are incompletely understood. In this study, we used a cross-species expression profiling strategy in metastatic cell lines of human and mouse origin to identify 22 up-regulated and 12 down-regulated genes that are part of an essential genetic program in metastasis. In particular, we identified a novel function in metastasis that was not previously known for the transcription factor Forkhead Box Q1 (Foxq1). Ectopic expression of Foxq1 increased cell migration and invasion in vitro, enhanced the lung metastatic capabilities of mammary epithelial cells in vivo, and triggered a marked EMT. In contrast, Foxq1 knockdown elicited converse effects on these phenotypes in vitro and in vivo. Neither ectopic expression nor knockdown of Foxq1 significantly affected cell proliferation or colony formation in vitro. Notably, Foxq1 repressed expression of the core EMT regulator E-cadherin by binding to the E-box in its promoter region. Further mechanistic investigation revealed that Foxq1 expression is regulated by TGF-β1, and that Foxq1 knockdown blocked TGF-β1-induced EMT at both morphological and molecular levels. Our findings highlight the feasibility of cross-species expression profiling as a strategy to identify metastasis-related genes, and they reveal that EMT induction is a likely mechanism underlying a novel metastasis-promoting function of Foxq1 defined here in breast cancer.
Rituximab plus CHOP (R-CHOP) significantly improved the outcome of diffuse large B cell lymphoma (DLBCL), a common sub-type of non-Hodgkin lymphoma. But 40% – 50% of DLBCL patients cannot be cured by this regimen. Some clinical trials showed that bevacizumab might be useful in the treatment of DLBCL. This study evaluated the safety and efficacy of bevacizumab combined with the R-CHOP (A-R-CHOP) regimen in Chinese patients with previously untreated DLBCL.
Patients with previously untreated DLBCL received A-R-CHOP regimen therapy. All patients with complete response (CR)/ unconfirmed complete response(CRu) after 8 cycles of A-R-CHOP received the bevacizumab maintenance therapy once every 3 weeks. The remained bulky disease was treated with radiotherapy.
Seven Chinese patients were treated. All of them had bulky diseases. One patient had progressive disease after 4 cycles of A-R-CHOP therapy. The rest six patients completed 8 cycles of A-R-CHOP treatment. All of these six patients reached CR/CRu (5 CR, 1 CRu). Bevacizumab maintenance therapy was given to 4 CR patients. All 7 patients experienced Grade 3/4 hematologic adverse events; additionally, one had Grade 3 gastrointestinal toxicity and one had Grade 1 epistaxis. During bevacizumab maintenance therapy, one patient had Grade 1 gingival bleeding, another experienced Grade 1 proteinuria and then Grade 3 congestive heart failure 4 months after completion of maintenance therapy. At the end of July 2013, the patient who had progressive disease after 4 cycles of A-R-CHOP died of progressive disease, the other six remained CR response.
The A-R-CHOP regimen is effective for untreated DLBCL, but may cause bevacizumab-specific toxicities, which should be monitored.
Bevacizumab; DLBCL; Safety; Efficacy
Enabling accurate analysis of social network data while preserving differential privacy has been challenging since graph features such as clustering coefficient or modularity often have high sensitivity, which is different from traditional aggregate functions (e.g., count and sum) on tabular data. In this paper, we treat a graph statistics as a function f and develop a divide and conquer approach to enforce differential privacy. The basic procedure of this approach is to first decompose the target computation f into several less complex unit computations f1, …, fm connected by basic mathematical operations (e.g., addition, subtraction, multiplication, division), then perturb the output of each fi with Laplace noise derived from its own sensitivity value and the distributed privacy threshold εi, and finally combine those perturbed fi as the perturbed output of computation f. We examine how various operations affect the accuracy of complex computations. When unit computations have large global sensitivity values, we enforce the differential privacy by calibrating noise based on the smooth sensitivity, rather than the global sensitivity. By doing this, we achieve the strict differential privacy guarantee with smaller magnitude noise. We illustrate our approach by using clustering coefficient, which is a popular statistics used in social network analysis. Empirical evaluations on five real social networks and various synthetic graphs generated from three random graph models show the developed divide and conquer approach outperforms the direct approach.
Genome variations in human papillomaviruses (HPVs) are common and have been widely investigated in the past two decades. HPV genotyping depends on the finding of the viral genome variations in the L1 ORF. Other parts of the viral genome variations have also been implicated as a possible genetic factor in viral pathogenesis and/or oncogenicity.
In this study, the HPV58 genome in cervical lesions was completely sequenced both by rolling-circle amplification of total cell DNA and deep sequencing (RCA-seq) and by long PCR template cloning and sequencing. By comparison of three HPV58 genome sequences decoded from three clinical samples to reference HPV-58, we demonstrated that RCA-seq is much more accurate than long-PCR template cloning and sequencing in decoding HPV58 genome. Three HPV58 genomes decoded by RCA-seq displayed a total of 52 nucleotide substitutions from reference HPV58, which could be verified by long PCR template cloning and sequencing. However, the long PCR template cloning and sequencing led to additional nucleotide substitutions, insertions, and deletions from an authentic HPV58 genome in a clinical sample, which vary from one cloned sequence to another. Because the inherited error-prone nature of Tgo DNA polymerase used in preparation of the long PCR templates of HPV58 genome from the clinical samples, the measurable error rate in incorporation of nucleotide into an elongating DNA template was about 0.149% ±0.038% in our studies.
Since PCR template cloning and sequencing is widely used in identification of single nucleotide polymorphism (SNP), our data indicate that a serious caution should be taken in finding of true SNPs in various genetic studies.
Human papillomaviruses; HPV58; Cervical cancer; Single nucleotide polymorphism; Genotyping; Genome variations; Rolling circle amplification; DNA deep sequencing
The variant antigen, Plasmodium falciparum erythrocyte membrane protein 1 (PfEMP1), expressed on the surface of P. falciparum infected Red Blood Cells (iRBCs) is a critical virulence factor for malaria1. Each parasite encodes 60 antigenically distinct var genes encoding PfEMP1s, but during infection the clonal parasite population expresses only one gene at a time before switching to the expression of a new variant antigen as an immune evasion mechanism to avoid the host’s antibody responses2,3. The mechanism by which 59 of the 60 var genes are silenced remains largely unknown4–7. Here we show that knocking out the P. falciparum variant-silencing SET gene (PfSETvs), which encodes an ortholog of Drosophila melanogaster ASH1 and controls histone H3 lysine 36 trimethylation (H3K36me3) on var genes, results in the transcription of virtually all var genes in the single parasite nuclei and their expression as proteins on the surface of individual iRBCs. PfSETvs-dependent H3K36me3 is present along the entire gene body including the transcription start site (TSS) to silence var genes. With low occupancy of PfSETvs at both the TSS of var genes and the intronic promoter, expression of var genes coincides with transcription of their corresponding antisense long non-coding RNA (lncRNA). These results uncover a novel role of the PfSETvs-dependent H3K36me3 in silencing var genes in P. falciparum that might provide a general mechanism by which orthologs of PfSETvs repress gene expression in other eukaryotes. PfSETvs knockout parasites expressing all PfEMP1s may also be applied to the development of a malaria vaccine.
Complementary in situ X-ray photoelectron
spectroscopy (XPS), X-ray
diffractometry, and environmental scanning electron microscopy are
used to fingerprint the entire graphene chemical vapor deposition
process on technologically important polycrystalline Cu catalysts
to address the current lack of understanding of the underlying fundamental
growth mechanisms and catalyst interactions. Graphene forms directly
on metallic Cu during the high-temperature hydrocarbon exposure, whereby
an upshift in the binding energies of the corresponding C1s XPS core
level signatures is indicative of coupling between the Cu catalyst
and the growing graphene. Minor carbon uptake into Cu can under certain
conditions manifest itself as carbon precipitation upon cooling. Postgrowth,
ambient air exposure even at room temperature decouples the graphene
from Cu by (reversible) oxygen intercalation. The importance of these
dynamic interactions is discussed for graphene growth, processing,
and device integration.
Graphene; chemical vapor deposition (CVD); polycrystalline copper
(Cu); in situ X-ray photoelectron
spectroscopy; in situ X-ray diffractometry; environmental
scanning electron microscopy; intercalation
This paper proposes a novel image mosaic method based on SIFT (Scale Invariant Feature Transform) feature of line segment, aiming to resolve incident scaling, rotation, changes in lighting condition, and so on between two images in the panoramic image mosaic process. This method firstly uses Harris corner detection operator to detect key points. Secondly, it constructs directed line segments, describes them with SIFT feature, and matches those directed segments to acquire rough point matching. Finally, Ransac method is used to eliminate wrong pairs in order to accomplish image mosaic. The results from experiment based on four pairs of images show that our method has strong robustness for resolution, lighting, rotation, and scaling.
Mortalin is an essential component of the molecular machinery that imports nuclear-encoded proteins into mitochondria, assists in their folding, and protects against damage upon accumulation of dysfunctional, unfolded proteins in aging mitochondria. Mortalin dysfunction associated with Parkinson’s disease (PD) increases the vulnerability of cultured cells to proteolytic stress and leads to changes in mitochondrial function and morphology. To date, Drosophila melanogaster has been successfully used to investigate pathogenesis following the loss of several other PD-associated genes. We generated the first loss-of-Hsc70-5/mortalin-function Drosophila model. The reduction of Mortalin expression recapitulates some of the defects observed in the existing Drosophila PD-models, which include reduced ATP levels, abnormal wing posture, shortened life span, and reduced spontaneous locomotor and climbing ability. Dopaminergic neurons seem to be more sensitive to the loss of mortalin than other neuronal sub-types and non-neuronal tissues. The loss of synaptic mitochondria is an early pathological change that might cause later degenerative events. It precedes both behavioral abnormalities and structural changes at the neuromuscular junction (NMJ) of mortalin-knockdown larvae that exhibit increased mitochondrial fragmentation. Autophagy is concomitantly up-regulated, suggesting that mitochondria are degraded via mitophagy. Ex vivo data from human fibroblasts identifies increased mitophagy as an early pathological change that precedes apoptosis. Given the specificity of the observed defects, we are confident that the loss-of-mortalin model presented in this study will be useful for further dissection of the complex network of pathways that underlie the development of mitochondrial parkinsonism.