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Systems Biology
A quantitative label-free analysis of the extracellular proteome of human supraspinatus tendon reveals damage to the pericellular and elastic fibre niches in torn and aged tissue
May 25, 2017   PloS One
Hakimi O, Ternette N, Murphy R, Kessler BM, Carr A
A quantitative label-free analysis of the extracellular proteome of human supraspinatus tendon reveals damage to the pericellular and elastic fibre niches in torn and aged tissue
May 25, 2017
PloS One
Tears of the human supraspinatus tendon are common and often cause painful and debilitating loss of function. Progressive failure of the tendon leading to structural abnormality and tearing is accompanied by numerous cellular and extra-cellular matrix (ECM) changes in the tendon tissue. This proteomics study aimed to compare torn and aged rotator cuff tissue to young and healthy tissue, and provide the first ECM inventory of human supraspinatus tendon generated using label-free quantitative LC-MS/MS. Employing two digestion protocols (trypsin and elastase), we analysed grain-sized tendon supraspinatus biopsies from older patients with torn tendons and from healthy, young controls. Our findings confirm measurable degradation of collagen fibrils and associated proteins in old and torn tendons, suggesting a significant loss of tissue organisation. A particularly marked reduction of cartilage oligomeric matrix protein (COMP) raises the possibility of using changes in levels of this glycoprotein as a marker of abnormal tissue, as previously suggested in horse models. Surprisingly, and despite using an elastase digestion for validation, elastin was not detected, suggesting that it is not highly abundant in human supraspinatus tendon as previously thought. Finally, we identified marked changes to the elastic fibre, fibrillin-rich niche and the pericellular matrix. Further investigation of these regions may yield other potential biomarkers and help to explain detrimental cellular processes associated with tendon ageing and tendinopathy.
Optimizing complex phenotypes through model-guided multiplex genome engineering
May 26, 2017   Genome Biology
Kuznetsov G, Goodman DB, Filsinger GT, Landon M, Rohland N, Aach J, Lajoie MJ, Church GM
Optimizing complex phenotypes through model-guided multiplex genome engineering
May 26, 2017
Genome Biology
We present a method for identifying genomic modifications that optimize a complex phenotype through multiplex genome engineering and predictive modeling. We apply our method to identify six single nucleotide mutations that recover 59% of the fitness defect exhibited by the 63-codon E. coli strain C321.∆A. By introducing targeted combinations of changes in multiplex we generate rich genotypic and phenotypic diversity and characterize clones using whole-genome sequencing and doubling time measurements. Regularized multivariate linear regression accurately quantifies individual allelic effects and overcomes bias from hitchhiking mutations and context-dependence of genome editing efficiency that would confound other strategies.
Validating regulatory predictions from diverse bacteria with mutant fitness data
May 25, 2017   PloS One
Sagawa S, Price MN, Deutschbauer AM, Arkin AP
Validating regulatory predictions from diverse bacteria with mutant fitness data
May 25, 2017
PloS One
Although transcriptional regulation is fundamental to understanding bacterial physiology, the targets of most bacterial transcription factors are not known. Comparative genomics has been used to identify likely targets of some of these transcription factors, but these predictions typically lack experimental support. Here, we used mutant fitness data, which measures the importance of each gene for a bacterium's growth across many conditions, to test regulatory predictions from RegPrecise, a curated collection of comparative genomics predictions. Because characterized transcription factors often have correlated fitness with one of their targets (either positively or negatively), correlated fitness patterns provide support for the comparative genomics predictions. At a false discovery rate of 3%, we identified significant cofitness for at least one target of 158 TFs in 107 ortholog groups and from 24 bacteria. Thus, high-throughput genetics can be used to identify a high-confidence subset of the sequence-based regulatory predictions.
Lipidomic and metabolic changes in the P4-type ATPase ATP10D deficient C57BL/6J wild type mice upon rescue of ATP10D function
May 25, 2017   PloS One
Sigruener A, Wolfrum C, Boettcher A, Kopf T, Liebisch G, Orsó E, Schmitz G
Lipidomic and metabolic changes in the P4-type ATPase ATP10D deficient C57BL/6J wild type mice upon rescue of ATP10D function
May 25, 2017
PloS One
Sequence variants near the human gene for P4-type ATPase, class V, type 10D (ATP10D) were shown to significantly associate with circulating hexosylceramide d18:1/16:0 and d18:1/24:1 levels, obesity, insulin resistance, plasma high density lipoprotein (HDL), coronary stenotic index and intracranial atherosclerotic index. In mice Atp10d is associated with HDL modulation and C57BL/6 mice expressing a truncated, non-functional form of ATP10D easily develop obesity and insulin resistance on high-fat diet. We analyzed metabolic differences of ATP10D deficient C57BL/6J wild type and ATP10D transgenic C57BL/6J BAC129 mice. ATP10D transgenic mice gain 25% less weight on high-fat diet concomitant with a reduced increase in fat cell mass but independent of adipocyte size change. ATP10D transgenic mice also had 26% lower triacylglycerol levels with approximately 76% bound to very low density lipoprotein while in ATP10D deficient wild type mice 57% are bound to low density lipoprotein. Furthermore increased oxygen consumption and CO2 production, 38% lower glucose and 69% lower insulin levels and better insulin sensitivity were observed in ATP10D transgenic mice. Besides decreased hexosylceramide species levels were detected. Part of these effects may be due to reduced hepatic stearoyl-CoA desaturase 1 (SCD1) expression in ATP10D transgenic mice, which was reflected by altered fatty acid and lipid species patterns. There was a significant decrease in the hepatic 18:1 to 18:0 free fatty acid ratio in transgenic mice. The ratio of 16:1 to 16:0 was not significantly different. Interestingly both ratios were significantly reduced in plasma total fatty acids. In summary we found that ATP10D reduces high-fat diet induced obesity and improves insulin sensitivity. ATP10D transgenic mice showed altered hepatic expression of lipid-metabolism associated genes, including Scd1, along with changes in hepatic and plasma lipid species and plasma lipoprotein pattern.
Exploratory plasma proteomic analysis in a randomized crossover trial of aspirin among healthy men and women
May 25, 2017   PloS One
Wang X, Shojaie A, Zhang Y, Shelley D, Lampe PD, Levy L, Peters U, Potter JD, White E, Lampe JW
Exploratory plasma proteomic analysis in a randomized crossover trial of aspirin among healthy men and women
May 25, 2017
PloS One
Long-term use of aspirin is associated with lower risk of colorectal cancer and other cancers; however, the mechanism of chemopreventive effect of aspirin is not fully understood. Animal studies suggest that COX-2, NFκB signaling and Wnt/β-catenin pathways may play a role, but no clinical trials have systematically evaluated the biological response to aspirin in healthy humans. Using a high-density antibody array, we assessed the difference in plasma protein levels after 60 days of regular dose aspirin (325 mg/day) compared to placebo in a randomized double-blinded crossover trial of 44 healthy non-smoking men and women, aged 21-45 years. The plasma proteome was analyzed on an antibody microarray with ~3,300 full-length antibodies, printed in triplicate. Moderated paired t-tests were performed on individual antibodies, and gene-set analyses were performed based on KEGG and GO pathways. Among the 3,000 antibodies analyzed, statistically significant differences in plasma protein levels were observed for nine antibodies after adjusting for false discoveries (FDR adjusted p-value
Host mediated inflammatory influence on glioblastoma multiforme recurrence following high-dose ionizing radiation
May 25, 2017   PloS One
McDonald JT, Gao X, Steber C, Lee Breed J, Pollock C, Ma L, Hlatky L
Host mediated inflammatory influence on glioblastoma multiforme recurrence following high-dose ionizing radiation
May 25, 2017
PloS One
Despite optimal clinical treatment, glioblastoma multiforme (GBM) inevitably recurs. Standard treatment of GBM, exposes patients to radiation which kills tumor cells, but also modulates the molecular fingerprint of any surviving tumor cells and the cross-talk between those cells and the host. Considerable investigation of short-term (hours to days) post-irradiation tumor cell response has been undertaken, yet long-term responses (weeks to months) which are potentially even more informative of recurrence, have been largely overlooked. To better understand the potential of these processes to reshape tumor regrowth, molecular studies in conjunction with in silico modeling were used to examine short- and long-term growth dynamics. Despite survival of 2.55% and 0.009% following 8 or 16Gy, GBM cell populations in vitro showed a robust escape from cellular extinction and a return to pre-irradiated growth rates with no changes in long-term population doublings. In contrast, these same irradiated GBM cell populations injected in vivo elicited tumors which displayed significantly suppressed growth rates compared to their pre-irradiated counterparts. Transcriptome analysis days to weeks after irradiation revealed, 281 differentially expressed genes with a robust increase for cytokines, histones and C-C or C-X-C motif chemokines in irradiated cells. Strikingly, this same inflammatory signature in vivo for IL1A, CXCL1, IL6 and IL8 was increased in xenografts months after irradiation. Computational modeling of tumor cell dynamics indicated a host-mediated negative pressure on the surviving cells was a source of inhibition consistent with the findings resulting in suppressed tumor growth. Thus, tumor cells surviving irradiation may shift the landscape of population doubling through inflammatory mediators interacting with the host in a way that impacts tumor recurrence and affects the efficacy of subsequent therapies. Clues to more effective therapies may lie in the development and use of pre-clinical models of post-treatment response to target the source of inflammatory mediators that significantly alter cellular dynamics and molecular pathways in the early stages of tumor recurrence.
Development and evaluation of a bioinformatics approach for designing molecular assays for viral detection
May 25, 2017   PloS One
Schneeberger PHH, Pothier JF, Bühlmann A, Duffy B, Beuret C, Utzinger J, Frey JE
Development and evaluation of a bioinformatics approach for designing molecular assays for viral detection
May 25, 2017
PloS One
Viruses belonging to the Flaviviridae and Bunyaviridae families show considerable genetic diversity. However, this diversity is not necessarily taken into account when developing diagnostic assays, which are often based on the pairwise alignment of a limited number of sequences. Our objective was to develop and evaluate a bioinformatics workflow addressing two recurrent issues of molecular assay design: (i) the high intraspecies genetic diversity in viruses and (ii) the potential for cross-reactivity with close relatives. The workflow developed herein was based on two consecutive BLASTn steps; the first was utilized to select highly conserved regions among the viral taxon of interest, and the second was employed to assess the degree of similarity of these highly-conserved regions to close relatives. Subsequently, the workflow was tested on a set of eight viral species, including various strains from the Flaviviridae and Bunyaviridae families. The genetic diversity ranges from as low as 0.45% variable sites over the complete genome of the Japanese encephalitis virus to more than 16% of variable sites on segment L of the Crimean-Congo hemorrhagic fever virus. Our proposed bioinformatics workflow allowed the selection-based on computing scores-of the best target for a diagnostic molecular assay for the eight viral species investigated. Our bioinformatics workflow allowed rapid selection of highly conserved and specific genomic fragments among the investigated viruses, while considering up to several hundred complete genomic sequences. The pertinence of this workflow will increase in parallel to the number of sequences made publicly available. We hypothesize that our workflow might be utilized to select diagnostic molecular markers for higher organisms with more complex genomes, provided the sequences are made available.
Transcriptome and proteomic analyses reveal multiple differences associated with chloroplast development in the spaceflight-induced wheat albino mutant mta
May 25, 2017   PloS One
Shi K, Gu J, Guo H, Zhao L, Xie Y, Xiong H, Li J, Zhao S, Song X, Liu L
Transcriptome and proteomic analyses reveal multiple differences associated with chloroplast development in the spaceflight-induced wheat albino mutant mta
May 25, 2017
PloS One
Chloroplast development is an integral part of plant survival and growth, and occurs in parallel with chlorophyll biosynthesis. However, little is known about the mechanisms underlying chloroplast development in hexaploid wheat. Here, we obtained a spaceflight-induced wheat albino mutant mta. Chloroplast ultra-structural observation showed that chloroplasts of mta exhibit abnormal morphology and distribution compared to wild type. Photosynthetic pigments content was also significantly decreased in mta. Transcriptome and chloroplast proteome profiling of mta and wild type were done to identify differentially expressed genes (DEGs) and proteins (DEPs), respectively. In total 4,588 DEGs including 1,980 up- and 2,608 down-regulated, and 48 chloroplast DEPs including 15 up- and 33 down-regulated were identified in mta. Classification of DEGs revealed that most were involved in chloroplast development, chlorophyll biosynthesis, or photosynthesis. Besides, transcription factors such as PIF3, GLK and MYB which might participate in those pathways were also identified. The correlation analysis between DEGs and DEPs revealed that the transcript-to-protein in abundance was functioned into photosynthesis and chloroplast relevant groups. Real time qPCR analysis validated that the expression level of genes encoding photosynthetic proteins was significantly decreased in mta. Together, our results suggest that the molecular mechanism for albino leaf color formation in mta is a thoroughly regulated and complicated process. The combined analysis of transcriptome and proteome afford comprehensive information for further research on chloroplast development mechanism in wheat. And spaceflight provides a potential means for mutagenesis in crop breeding.
Proteome dynamics of cold-acclimating Rhododendron species contrasting in their freezing tolerance and thermonasty behavior
May 25, 2017   PloS One
Die JV, Arora R, Rowland LJ
Proteome dynamics of cold-acclimating Rhododendron species contrasting in their freezing tolerance and thermonasty behavior
May 25, 2017
PloS One
To gain a better understanding of cold acclimation in rhododendron and in woody perennials in general, we used the 2D-DIGE technique to analyze the rhododendron proteome during the seasonal development of freezing tolerance. We selected two species varying in their cold acclimation ability as well as their thermonasty response (folding of leaves in response to low temperature). Proteins were extracted from leaves of non-acclimated (NA) and cold acclimated (CA) plants of the hardier thermonastic species, R. catawbiense (Cata.), and from leaves of cold acclimated plants of the less hardy, non-thermonastic R. ponticum (Pont.). All three protein samples (Cata.NA, Cata.CA, and Pont.CA) were labeled with different CyDyes and separated together on a single gel. Triplicate gels were run and protein profiles were compared resulting in the identification of 72 protein spots that consistently had different abundances in at least one pair-wise comparison. From the 72 differential spots, we chose 56 spots to excise and characterize further by mass spectrometry (MS). Changes in the proteome associated with the seasonal development of cold acclimation were identified from the Cata.CA-Cata.NA comparisons. Differentially abundant proteins associated with the acquisition of superior freezing tolerance and with the thermonastic response were identified from the Cata.CA-Pont.CA comparisons. Our results indicate that cold acclimation in rhododendron involves increases in abundance of several proteins related to stress (freezing/desiccation tolerance), energy and carbohydrate metabolism, regulation/signaling, secondary metabolism (possibly involving cell wall remodeling), and permeability of the cell membrane. Cold acclimation also involves decreases in abundance of several proteins involved in photosynthesis. Differences in freezing tolerance between genotypes can probably be attributed to observed differences in levels of proteins involved in these functions. Also differences in freezing tolerance may be attributed to higher levels of some constitutive protective proteins in Cata. than in Pont. that may be required to overcome freeze damage, such as glutathione peroxidase, glutamine synthetase, and a plastid-lipid-associated protein.
Zika virus evolution and spread in the Americas
May 24, 2017   Nature Add nature.com free-link Cancel
Metsky HC, Matranga CB, Wohl S, Schaffner SF, Freije CA,   . . . . . .   , Souza TML, Bosch I, Yozwiak NL, MacInnis BL, Sabeti PC
Zika virus evolution and spread in the Americas
May 24, 2017
Nature
Although the recent Zika virus (ZIKV) epidemic in the Americas and its link to birth defects have attracted a great deal of attention, much remains unknown about ZIKV disease epidemiology and ZIKV evolution, in part owing to a lack of genomic data. Here we address this gap in knowledge by using multiple sequencing approaches to generate 110 ZIKV genomes from clinical and mosquito samples from 10 countries and territories, greatly expanding the observed viral genetic diversity from this outbreak. We analysed the timing and patterns of introductions into distinct geographic regions; our phylogenetic evidence suggests rapid expansion of the outbreak in Brazil and multiple introductions of outbreak strains into Puerto Rico, Honduras, Colombia, other Caribbean islands, and the continental United States. We find that ZIKV circulated undetected in multiple regions for many months before the first locally transmitted cases were confirmed, highlighting the importance of surveillance of viral infections. We identify mutations with possible functional implications for ZIKV biology and pathogenesis, as well as those that might be relevant to the effectiveness of diagnostic tests.
Genomic epidemiology reveals multiple introductions of Zika virus into the United States
May 24, 2017   Nature Add nature.com free-link Cancel
Grubaugh ND, Ladner JT, Kraemer MUG, Dudas G, Tan AL,   . . . . . .   , Bedford T, Pybus OG, Isern S, Palacios G, Andersen KG
Genomic epidemiology reveals multiple introductions of Zika virus into the United States
May 24, 2017
Nature
Zika virus (ZIKV) is causing an unprecedented epidemic linked to severe congenital abnormalities. In July 2016, mosquito-borne ZIKV transmission was reported in the continental United States; since then, hundreds of locally acquired infections have been reported in Florida. To gain insights into the timing, source, and likely route(s) of ZIKV introduction, we tracked the virus from its first detection in Florida by sequencing ZIKV genomes from infected patients and Aedes aegypti mosquitoes. We show that at least 4 introductions, but potentially as many as 40, contributed to the outbreak in Florida and that local transmission is likely to have started in the spring of 2016-several months before its initial detection. By analysing surveillance and genetic data, we show that ZIKV moved among transmission zones in Miami. Our analyses show that most introductions were linked to the Caribbean, a finding corroborated by the high incidence rates and traffic volumes from the region into the Miami area. Our study provides an understanding of how ZIKV initiates transmission in new regions.
Noncoding after All: Biases in Proteomics Data Do Not Explain Observed Absence of lncRNA Translation Products
May 23, 2017   Journal Of Proteome Research
Verheggen K, Volders PJ, Mestdagh P, Menschaert G, Van Damme P, Gevaert K, Martens L, Vandesompele J
Noncoding after All: Biases in Proteomics Data Do Not Explain Observed Absence of lncRNA Translation Products
May 23, 2017
Journal Of Proteome Research
Over the past decade, long noncoding RNAs (lncRNAs) have emerged as novel functional entities of the eukaryotic genome. However, the scientific community remains divided over the amount of true noncoding transcripts among the large number of unannotated transcripts identified by recent large scale and deep RNA-sequencing efforts. Here, we systematically exclude possible technical reasons underlying the absence of lncRNA-encoded proteins in mass spectrometry data sets, strongly suggesting that the large majority of lncRNAs is indeed not translated.
Sex-specific metabolic profiles of androgens and its main binding protein SHBG in a middle aged population without diabetes
May 23, 2017   Scientific Reports
Piontek U, Wallaschofski H, Kastenmüller G, Suhre K, Völzke H, Do KT, Artati A, Nauck M, Adamski J, Friedrich N, Pietzner M
Sex-specific metabolic profiles of androgens and its main binding protein SHBG in a middle aged population without diabetes
May 23, 2017
Scientific Reports
The role of androgens in metabolism with respect to sex-specific disease associations is poorly understood. Therefore, we aimed to provide molecular signatures in plasma and urine of androgen action in a sex-specific manner using state-of-the-art metabolomics techniques. Our study population consisted of 430 men and 343 women, aged 20-80 years, who were recruited for the cross-sectional population-based Study of Health in Pomerania (SHIP-TREND), Germany. We used linear regression models to identify associations between testosterone, androstenedione and dehydroepiandrosterone-sulfate (DHEAS) as well as sex hormone-binding globulin and plasma or urine metabolites measured by mass spectrometry. The analyses revealed major sex-specific differences in androgen-associated metabolites, particularly for levels of urate, lipids and metabolic surrogates of lifestyle factors, like cotinine or piperine. In women, in particular in the postmenopausal state, androgens showed a greater impact on the metabolome than in men (especially DHEAS and lipids were highly related in women). We observed a novel association of androstenedione on the metabolism of biogenic amines and only a small sex-overlap of associations within steroid metabolism. The present study yields new insights in the interaction between androgens and metabolism, especially about their implication in female metabolism.
Genome Partitioner: A web tool for multi-level partitioning of large-scale DNA constructs for synthetic biology applications
May 22, 2017   PloS One
Christen M, Del Medico L, Christen H, Christen B
Genome Partitioner: A web tool for multi-level partitioning of large-scale DNA constructs for synthetic biology applications
May 22, 2017
PloS One
Recent advances in lower-cost DNA synthesis techniques have enabled new innovations in the field of synthetic biology. Still, efficient design and higher-order assembly of genome-scale DNA constructs remains a labor-intensive process. Given the complexity, computer assisted design tools that fragment large DNA sequences into fabricable DNA blocks are needed to pave the way towards streamlined assembly of biological systems. Here, we present the Genome Partitioner software implemented as a web-based interface that permits multi-level partitioning of genome-scale DNA designs. Without the need for specialized computing skills, biologists can submit their DNA designs to a fully automated pipeline that generates the optimal retrosynthetic route for higher-order DNA assembly. To test the algorithm, we partitioned a 783 kb Caulobacter crescentus genome design. We validated the partitioning strategy by assembling a 20 kb test segment encompassing a difficult to synthesize DNA sequence. Successful assembly from 1 kb subblocks into the 20 kb segment highlights the effectiveness of the Genome Partitioner for reducing synthesis costs and timelines for higher-order DNA assembly. The Genome Partitioner is broadly applicable to translate DNA designs into ready to order sequences that can be assembled with standardized protocols, thus offering new opportunities to harness the diversity of microbial genomes for synthetic biology applications. The Genome Partitioner web tool can be accessed at https://christenlab.ethz.ch/GenomePartitioner.
The serum protein responses to treatment with Xiaoke Pill and Glibenclamide in type 2 diabetes patients
May 22, 2017   Clinical Proteomics
Zhang X, Sun H, Paul SK, Wang Q, Lou X, Hou G, Wen B, Ji L, Liu S
The serum protein responses to treatment with Xiaoke Pill and Glibenclamide in type 2 diabetes patients
May 22, 2017
Clinical Proteomics
The Xiaoke Pill containing Chinese herb extracts and Glibenclamide, is used in therapy for type 2 diabetes mellitus (T2DM), and is effective in reducing the risk of hypoglycemia and improving diabetes symptoms compared with Glibenclamide. We describe a quantitative proteomics project to measure the T2DM serum proteome response to the Xiaoke Pill and Glibenclamide. Based on a recently conducted 48-week clinical trial comparing the safety and efficacy of Glibenclamide (n = 400) and Xiaoke Pill (n = 400), after matching for age, sex, BMI, drug dose and whether hypoglycemia occurred, 32 patients were selected for the serum based proteomic analysis and divided into four groups (with/without hypoglycemia treated with Xiaoke Pill or Glibenclamide, n = 8 for each group). We screened the differential serum proteins related to treatments and the onset of hypoglycemia using the iTRAQ labeling quantitative proteomics technique. Baseline and follow-up samples were used. The quantitative proteomics experiments demonstrated that 25 and 21 proteins differed upon treatment with the Xiaoke Pill in patients without and with hypoglycemia, respectively, while 24 and 25 proteins differed upon treatment with Glibenclamide in patients without and with hypoglycemia, respectively. The overlap of different proteins between the patients with and without hypoglycemia given the same drug treatment was much greater than between the patients given different drug treatments. We conclude that the serum proteins response to the two different anti-diabetic drug treatments may serve as a sensitive biomarker for evaluation of the therapeutic effects and continue investigations into the mechanism.
Associating cellular epigenetic models with human phenotypes
May 30, 2017   Nature Reviews. Genetics
Lappalainen T, Greally JM
Associating cellular epigenetic models with human phenotypes
May 30, 2017
Nature Reviews. Genetics
Epigenetic association studies have been carried out to test the hypothesis that environmental perturbations trigger cellular reprogramming, with downstream effects on cellular function and phenotypes. There have now been numerous studies of the potential molecular mediators of epigenetic changes by epigenome-wide association studies (EWAS). However, a challenge for the field is the interpretation of the results obtained. We describe a second-generation EWAS approach, which focuses on the possible cellular models of epigenetic perturbations, studied by rigorous analysis and interpretation of genomic data. Thus refocused, epigenetics research aligns with the field of functional genomics to provide insights into environmental and genetic influences on phenotypic variation in humans.
The identification of switch-like alternative splicing exons among multiple samples with RNA-Seq data
May 25, 2017   PloS One
Qin Z, Zhang X
The identification of switch-like alternative splicing exons among multiple samples with RNA-Seq data
May 25, 2017
PloS One
Alternative splicing is an ubiquitous phenomenon in most human genes and has important functions. The switch-like exon is the type of exon that has a high level of usage in some tissues, but has a low level of usage in the other tissues. They usually undergo strong tissue-specific regulations. There is still a lack a systematic method to identify switch-like exons from multiple RNA-seq samples. We proposed a novel method called iterative Tertile Absolute Deviation around the mode (iTAD) to profile the distribution of exon relative usages among multiple samples and to identify switch-like exons and other types of exons using a robust statistic estimator. We validated the method with simulation data, and applied it on RNA-seq data of 16 human body tissues and detected 3,100 switch-like exons. We found that switch-like exons tend to be more associated with Alu elements in their flanking intron regions than other types of exons.
Molecular heterogeneity at the network level: high-dimensional testing, clustering and a TCGA case study
May 23, 2017   Bioinformatics (Oxford, England)
Städler N, Dondelinger F, Hill SM, Akbani R, Lu Y, Mills GB, Mukherjee S
Molecular heterogeneity at the network level: high-dimensional testing, clustering and a TCGA case study
May 23, 2017
Bioinformatics (Oxford, England)
Molecular pathways and networks play a key role in basic and disease biology. An emerging notion is that networks encoding patterns of molecular interplay may themselves differ between contexts, such as cell type, tissue or disease (sub)type. However, while statistical testing of differences in mean expression levels has been extensively studied, testing of network differences remains challenging. Furthermore, since network differences could provide important and biologically interpretable information to identify molecular subgroups, there is a need to consider the unsupervised task of learning subgroups and networks that define them. This is a nontrivial clustering problem, with neither subgroups nor subgroup-specific networks known at the outset. We leverage recent ideas from high-dimensional statistics for testing and clustering in the network biology setting. The methods we describe can be applied directly to most continuous molecular measurements and networks do not need to be specified beforehand. We illustrate the ideas and methods in a case study using protein data from the Cancer Genome Atlas (TCGA). This provides evidence that patterns of interplay between signalling proteins differ significantly between cancer types. Furthermore, we show how the proposed approaches can be used to learn subtypes and the molecular networks that define them. As the Bioconductor package nethet . staedler.n@gmail.com , sach.mukherjee@dzne.de.
PhyD3: a phylogenetic tree viewer with extended phyloXML support for functional genomics data visualization
May 19, 2017   Bioinformatics (Oxford, England)
Kreft L, Botzki A, Coppens F, Vandepoele K, Van Bel M
PhyD3: a phylogenetic tree viewer with extended phyloXML support for functional genomics data visualization
May 19, 2017
Bioinformatics (Oxford, England)
Comparative and evolutionary studies utilise phylogenetic trees to analyse and visualise biological data. Recently, several web-based tools for the display, manipulation, and annotation of phylogenetic trees, such as iTOL and Evolview, have released updates to be compatible with the latest web technologies. While those web tools operate an open server access model with a multitude of registered users, a feature-rich open source solution using current web technologies is not available. Here, we present an extension of the widely used PhyloXML standard with several new options to accommodate functional genomics or annotation datasets for advanced visualization. Furthermore, PhyD3 has been developed as a lightweight tool using the JavaScript library D3.js to achieve a state-of-the-art phylogenetic tree visualisation in the web browser, with support for advanced annotations. The current implementation is open source, easily adaptable and easy to implement in third parties' web sites. More information about PhyD3 itself, installation procedures, and implementation links are available at http://phyd3.bits.vib.be and at http://github.com/vibbits/phyd3/ . bits@vib.be. Supplementary data is available at Bioinformatics online.
The distinct metabolic phenotype of lung squamous cell carcinoma defines selective vulnerability to glycolytic inhibition
May 26, 2017   Nature Communications
Goodwin J, Neugent ML, Lee SY, Choe JH, Choi H,   . . . . . .   , Minna JD, Helke KL, Singh PK, Shackelford DB, Kim JW
The distinct metabolic phenotype of lung squamous cell carcinoma defines selective vulnerability to glycolytic inhibition
May 26, 2017
Nature Communications
Adenocarcinoma (ADC) and squamous cell carcinoma (SqCC) are the two predominant subtypes of non-small cell lung cancer (NSCLC) and are distinct in their histological, molecular and clinical presentation. However, metabolic signatures specific to individual NSCLC subtypes remain unknown. Here, we perform an integrative analysis of human NSCLC tumour samples, patient-derived xenografts, murine model of NSCLC, NSCLC cell lines and The Cancer Genome Atlas (TCGA) and reveal a markedly elevated expression of the GLUT1 glucose transporter in lung SqCC, which augments glucose uptake and glycolytic flux. We show that a critical reliance on glycolysis renders lung SqCC vulnerable to glycolytic inhibition, while lung ADC exhibits significant glucose independence. Clinically, elevated GLUT1-mediated glycolysis in lung SqCC strongly correlates with high 18F-FDG uptake and poor prognosis. This previously undescribed metabolic heterogeneity of NSCLC subtypes implicates significant potential for the development of diagnostic, prognostic and targeted therapeutic strategies for lung SqCC, a cancer for which existing therapeutic options are clinically insufficient.
Optimized fragmentation schemes and data analysis strategies for proteome-wide cross-link identification
May 19, 2017   Nature Communications
Liu F, Lössl P, Scheltema R, Viner R, Heck AJR
Optimized fragmentation schemes and data analysis strategies for proteome-wide cross-link identification
May 19, 2017
Nature Communications
We describe optimized fragmentation schemes and data analysis strategies substantially enhancing the depth and accuracy in identifying protein cross-links using non-restricted whole proteome databases. These include a novel hybrid data acquisition strategy to sequence cross-links at both MS2 and MS3 level and a new algorithmic design XlinkX v2.0 for data analysis. As proof-of-concept we investigated proteome-wide protein interactions in E. coli and HeLa cell lysates, respectively, identifying 1,158 and 3,301 unique cross-links at ∼1% false discovery rate. These protein interaction repositories provide meaningful structural information on many endogenous macromolecular assemblies, as we showcase on several protein complexes involved in translation, protein folding and carbohydrate metabolism.
Crystal structure of the receptor binding domain of the spike glycoprotein of human betacoronavirus HKU1
May 23, 2017   Nature Communications
Ou X, Guan H, Qin B, Mu Z, Wojdyla JA, Wang M, Dominguez SR, Qian Z, Cui S
Crystal structure of the receptor binding domain of the spike glycoprotein of human betacoronavirus HKU1
May 23, 2017
Nature Communications
Human coronavirus (CoV) HKU1 is a pathogen causing acute respiratory illnesses and so far little is known about its biology. HKU1 virus uses its S1 subunit C-terminal domain (CTD) and not the N-terminal domain like other lineage A β-CoVs to bind to its yet unknown human receptor. Here we present the crystal structure of HKU1 CTD at 1.9 Å resolution. The structure consists of three subdomains: core, insertion and subdomain-1 (SD-1). While the structure of the core and SD-1 subdomains of HKU1 are highly similar to those of other β-CoVs, the insertion subdomain adopts a novel fold, which is largely invisible in the cryo-EM structure of the HKU1 S trimer. We identify five residues in the insertion subdomain that are critical for binding of neutralizing antibodies and two residues essential for receptor binding. Our study contributes to a better understanding of entry, immunity and evolution of CoV S proteins.
WIPI3 and WIPI4 β-propellers are scaffolds for LKB1-AMPK-TSC signalling circuits in the control of autophagy
May 31, 2017   Nature Communications
Bakula D, Müller AJ, Zuleger T, Takacs Z, Franz-Wachtel M, Thost AK, Brigger D, Tschan MP, Frickey T, Robenek H, Macek B, Proikas-Cezanne T
WIPI3 and WIPI4 β-propellers are scaffolds for LKB1-AMPK-TSC signalling circuits in the control of autophagy
May 31, 2017
Nature Communications
Autophagy is controlled by AMPK and mTOR, both of which associate with ULK1 and control the production of phosphatidylinositol 3-phosphate (PtdIns3P), a prerequisite for autophagosome formation. Here we report that WIPI3 and WIPI4 scaffold the signal control of autophagy upstream of PtdIns3P production and have a role in the PtdIns3P effector function of WIPI1-WIPI2 at nascent autophagosomes. In response to LKB1-mediated AMPK stimulation, WIPI4-ATG2 is released from a WIPI4-ATG2/AMPK-ULK1 complex and translocates to nascent autophagosomes, controlling their size, to which WIPI3, in complex with FIP200, also contributes. Upstream, WIPI3 associates with AMPK-activated TSC complex at lysosomes, regulating mTOR. Our WIPI interactome analysis reveals the scaffold functions of WIPI proteins interconnecting autophagy signal control and autophagosome formation. Our functional kinase screen uncovers a novel regulatory link between LKB1-mediated AMPK stimulation that produces a direct signal via WIPI4, and we show that the AMPK-related kinases NUAK2 and BRSK2 regulate autophagy through WIPI4.
Targeted Degradation of CTCF Decouples Local Insulation of Chromosome Domains from Genomic Compartmentalization
May 19, 2017   Cell
Nora EP, Goloborodko A, Valton AL, Gibcus JH, Uebersohn A, Abdennur N, Dekker J, Mirny LA, Bruneau BG
Targeted Degradation of CTCF Decouples Local Insulation of Chromosome Domains from Genomic Compartmentalization
May 19, 2017
Cell
The molecular mechanisms underlying folding of mammalian chromosomes remain poorly understood. The transcription factor CTCF is a candidate regulator of chromosomal structure. Using the auxin-inducible degron system in mouse embryonic stem cells, we show that CTCF is absolutely and dose-dependently required for looping between CTCF target sites and insulation of topologically associating domains (TADs). Restoring CTCF reinstates proper architecture on altered chromosomes, indicating a powerful instructive function for CTCF in chromatin folding. CTCF remains essential for TAD organization in non-dividing cells. Surprisingly, active and inactive genome compartments remain properly segregated upon CTCF depletion, revealing that compartmentalization of mammalian chromosomes emerges independently of proper insulation of TADs. Furthermore, our data support that CTCF mediates transcriptional insulator function through enhancer blocking but not as a direct barrier to heterochromatin spreading. Beyond defining the functions of CTCF in chromosome folding, these results provide new fundamental insights into the rules governing mammalian genome organization. Copyright © 2017 Elsevier Inc. All rights reserved.
Mapping the proteome
May 26, 2017   Science (New York, N.Y.)
Vinson V
Mapping the proteome
May 26, 2017
Science (New York, N.Y.)

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