Showing papers in "Nature Biotechnology in 2010"
TL;DR: The results suggest that Cufflinks can illuminate the substantial regulatory flexibility and complexity in even this well-studied model of muscle development and that it can improve transcriptome-based genome annotation.
Abstract: High-throughput mRNA sequencing (RNA-Seq) promises simultaneous transcript discovery and abundance estimation. However, this would require algorithms that are not restricted by prior gene annotations and that account for alternative transcription and splicing. Here we introduce such algorithms in an open-source software program called Cufflinks. To test Cufflinks, we sequenced and analyzed >430 million paired 75-bp RNA-Seq reads from a mouse myoblast cell line over a differentiation time series. We detected 13,692 known transcripts and 3,724 previously unannotated ones, 62% of which are supported by independent expression data or by homologous genes in other species. Over the time series, 330 genes showed complete switches in the dominant transcription start site (TSS) or splice isoform, and we observed more subtle shifts in 1,304 other genes. These results suggest that Cufflinks can illuminate the substantial regulatory flexibility and complexity in even this well-studied model of muscle development and that it can improve transcriptome-based genome annotation.
13,337 citations
TL;DR: The Genomic Regions Enrichment of Annotations Tool (GREAT) is developed to analyze the functional significance of cis-regulatory regions identified by localized measurements of DNA binding events across an entire genome.
Abstract: We developed the Genomic Regions Enrichment of Annotations Tool (GREAT) to analyze the functional significance of cis-regulatory regions identified by localized measurements of DNA binding events across an entire genome. Whereas previous methods took into account only binding proximal to genes, GREAT is able to properly incorporate distal binding sites and control for false positives using a binomial test over the input genomic regions. GREAT incorporates annotations from 20 ontologies and is available as a web application. Applying GREAT to data sets from chromatin immunoprecipitation coupled with massively parallel sequencing (ChIP-seq) of multiple transcription-associated factors, including SRF, NRSF, GABP, Stat3 and p300 in different developmental contexts, we recover many functions of these factors that are missed by existing gene-based tools, and we generate testable hypotheses. The utility of GREAT is not limited to ChIP-seq, as it could also be applied to open chromatin, localized epigenomic markers and similar functional data sets, as well as comparative genomics sets.
3,730 citations
TL;DR: This primer covers the theoretical basis of the approach, several practical examples and a software toolbox for performing the calculations.
Abstract: Flux balance analysis is a mathematical approach for analyzing the flow of metabolites through a metabolic network. This primer covers the theoretical basis of the approach, several practical examples and a software toolbox for performing the calculations.
3,229 citations
TL;DR: A comprehensive understanding of epigenetic mechanisms, their interactions and alterations in health and disease, has become a priority in biomedical research.
Abstract: Epigenetics is one of the most rapidly expanding fields in biology. The recent characterization of a human DNA methylome at single nucleotide resolution, the discovery of the CpG island shores, the finding of new histone variants and modifications, and the unveiling of genome-wide nucleosome positioning maps highlight the accelerating speed of discovery over the past two years. Increasing interest in epigenetics has been accompanied by technological breakthroughs that now make it possible to undertake large-scale epigenomic studies. These allow the mapping of epigenetic marks, such as DNA methylation, histone modifications and nucleosome positioning, which are critical for regulating gene and noncoding RNA expression. In turn, we are learning how aberrant placement of these epigenetic marks and mutations in the epigenetic machinery is involved in disease. Thus, a comprehensive understanding of epigenetic mechanisms, their interactions and alterations in health and disease, has become a priority in biomedical research.
2,458 citations
TL;DR: The analysis here suggests that state stem cell funding programs are sufficiently large and established that simply ending the programs, at least in the absence of substantial investment in the field by other funding sources, could have deleterious effects.
Abstract: 1. Anonymous. Nat. Biotechnol. 28, 987 (2010). 2. Plosila, W.H. Econ. Dev. Q. 18, 113–126 (2004). 3. Stayn, S. BNA Med. Law Pol. Rep. 5, 718–725 (2006). 4. Lomax, G. & Stayn, S. BNA Med. Law Pol. Rep. 7, 695–698 (2008). 5. Levine, A.D. Public Adm. Rev. 68, 681–694 (2008). 6. Levine, A.D. Nat. Biotechnol. 24, 865–866 (2006). 7. McCormick, J.B., Owen-Smith, J. & Scott, C.T. Cell Stem Cell 4, 107–110 (2009). 8. Fossett, J.W., Ouellette, A.R., Philpott, S., Magnus, D. & Mcgee, G. Hastings Cent. Rep. 37, 24–35 (2007). 9. Mintrom, M. Publius 39, 606–631 (2009). 10. Scott, C.T., McCormick, J.B. & Owen-Smith, J. Nat. Biotechnol. 27, 696–697 (2009). 11. Takahashi, K. & Yamanaka, S. Cell 126, 663–676 (2006). Foundation and the Georgia Research Alliance, and Georgia Tech. They thank J. Walsh at Georgia Tech for helpful comments on an earlier version of this manuscript. They also appreciate the assistance they received with data collection from officials in various state stem cell agencies. A.D.L. would also like to thank A. Jakimo, whose comment at a meeting of the Interstate Alliance on Stem Cell Research inspired collection of these data. stem cell programs, as well as similar state programs supporting other areas of science, is uncertain. The analysis here suggests that state stem cell funding programs are sufficiently large and established that simply ending the programs, at least in the absence of substantial investment in the field by other funding sources, could have deleterious effects. Such action would fail to capitalize on the initial efforts of scientists who have been drawn to the field of stem cell research by state programs and leave many stem cell scientists suddenly searching for funding to continue their research. Large-scale state funding for basic research is a relatively new phenomenon, and many questions remain about the impact of these programs on the development of scientific fields and the careers of scientists. The influence of state funding programs on the distribution of research publications, the acquisition of future external funding, the creation of new companies and the translation of basic research into medical practice, for instance, are important unanswered questions. Similarly, comparing state funding programs with federal funding programs as well as foundations could offer new insight into the relative priorities of different funding bodies and the extent to which their funding portfolios overlap or are distinct. We hope the analysis presented here and the public release of the underlying database will inspire additional analysis of state science funding programs generally and state-funded stem cell science in particular.
2,131 citations
Harvard University1, University of Washington2, University of California, San Francisco3, University of California, San Diego4, Baylor College of Medicine5, Broad Institute6, University of British Columbia7, Salk Institute for Biological Studies8, University of California, Davis9, University of Wisconsin-Madison10
TL;DR: The NIH Roadmap Epigenomics Mapping Consortium aims to produce a public resource of epigenomic maps for stem cells and primary ex vivo tissues selected to represent the normal counterparts of tissues and organ systems frequently involved in human disease.
Abstract: The NIH Roadmap Epigenomics Mapping Consortium aims to produce a public resource of epigenomic maps for stem cells and primary ex vivo tissues selected to represent the normal counterparts of tissues and organ systems frequently involved in human disease.
1,724 citations
TL;DR: The authors' single-molecule enzyme-linked immunosorbent assay (digital ELISA) approach detected as few as ∼10–20 enzyme-labeled complexes in 100 μl of sample and routinely allowed detection of clinically relevant proteins in serum at concentrations much lower than conventional ELISA.
Abstract: The ability to detect single protein molecules in blood could accelerate the discovery and use of more sensitive diagnostic biomarkers. To detect low-abundance proteins in blood, we captured them on microscopic beads decorated with specific antibodies and then labeled the immunocomplexes (one or zero labeled target protein molecules per bead) with an enzymatic reporter capable of generating a fluorescent product. After isolating the beads in 50-fl reaction chambers designed to hold only a single bead, we used fluorescence imaging to detect single protein molecules. Our single-molecule enzyme-linked immunosorbent assay (digital ELISA) approach detected as few as approximately 10-20 enzyme-labeled complexes in 100 microl of sample (approximately 10(-19) M) and routinely allowed detection of clinically relevant proteins in serum at concentrations (<10(-15) M) much lower than conventional ELISA. Digital ELISA detected prostate-specific antigen (PSA) in sera from patients who had undergone radical prostatectomy at concentrations as low as 14 fg/ml (0.4 fM).
1,554 citations
TL;DR: The best-performing lipid recovered after screening (DLin-KC2-DMA) was formulated and characterized in SNALP and demonstrated to have in vivo activity at siRNA doses as low as 0.01 mg/kg in rodents and 0.1 mg/ kg in nonhuman primates, a substantial improvement over previous reports of in vivo endogenous hepatic gene silencing.
Abstract: We adopted a rational approach to design cationic lipids for use in formulations to deliver small interfering RNA (siRNA). Starting with the ionizable cationic lipid 1,2-dilinoleyloxy-3-dimethylaminopropane (DLinDMA), a key lipid component of stable nucleic acid lipid particles (SNALP) as a benchmark, we used the proposed in vivo mechanism of action of ionizable cationic lipids to guide the design of DLinDMA-based lipids with superior delivery capacity. The best-performing lipid recovered after screening (DLin-KC2-DMA) was formulated and characterized in SNALP and demonstrated to have in vivo activity at siRNA doses as low as 0.01 mg/kg in rodents and 0.1 mg/kg in nonhuman primates. To our knowledge, this represents a substantial improvement over previous reports of in vivo endogenous hepatic gene silencing.
1,459 citations
TL;DR: Scripture, a method to reconstruct the transcriptome of a mammalian cell using only RNA-Seq reads and the genome sequence, is presented and the power of ab initio reconstruction is demonstrated to render a comprehensive picture of mammalian transcriptomes.
Abstract: High-throughput sequencing of total cellular RNA by RNA-Seq promises rapid reconstruction of spliced transcripts in a cell population. Guttman et al. accomplish this using only paired-end RNA-seq data and an unannotated genome sequence, and apply the method to better define many new, conserved long intergenic noncoding RNAs (lincRNAs).
1,326 citations
TL;DR: It is shown that iPSCs obtained from mouse fibroblasts, hematopoietic and myogenic cells exhibit distinct transcriptional and epigenetic patterns, and it is demonstrated that cellular origin influences the in vitro differentiation potentials of iPSC into embryoid bodies and different hematopsic cell types.
Abstract: Induced pluripotent stem cells (iPSCs) have been derived from various somatic cell populations through ectopic expression of defined factors. It remains unclear whether iPSCs generated from different cell types are molecularly and functionally similar. Here we show that iPSCs obtained from mouse fibroblasts, hematopoietic and myogenic cells exhibit distinct transcriptional and epigenetic patterns. Moreover, we demonstrate that cellular origin influences the in vitro differentiation potentials of iPSCs into embryoid bodies and different hematopoietic cell types. Notably, continuous passaging of iPSCs largely attenuates these differences. Our results suggest that early-passage iPSCs retain a transient epigenetic memory of their somatic cells of origin, which manifests as differential gene expression and altered differentiation capacity. These observations may influence ongoing attempts to use iPSCs for disease modeling and could also be exploited in potential therapeutic applications to enhance differentiation into desired cell lineages.
1,147 citations
TL;DR: The Model SEED is introduced, a web-based resource for high-throughput generation, optimization and analysis of genome-scale metabolic models and introduces techniques to automate nearly every step of this process, taking ∼48 h to reconstruct a metabolic model from an assembled genome sequence.
Abstract: Genome-scale metabolic models have proven to be valuable for predicting organism phenotypes from genotypes. Yet efforts to develop new models are failing to keep pace with genome sequencing. To address this problem, we introduce the Model SEED, a web-based resource for high-throughput generation, optimization and analysis of genome-scale metabolic models. The Model SEED integrates existing methods and introduces techniques to automate nearly every step of this process, taking approximately 48 h to reconstruct a metabolic model from an assembled genome sequence. We apply this resource to generate 130 genome-scale metabolic models representing a taxonomically diverse set of bacteria. Twenty-two of the models were validated against available gene essentiality and Biolog data, with the average model accuracy determined to be 66% before optimization and 87% after optimization.
TL;DR: A multivariate Hidden Markov Model is used to reveal 'chromatin states' in human T cells, based on recurrent and spatially coherent combinations of chromatin marks, providing a complementary functional annotation of the human genome that reveals the genome-wide locations of diverse classes of epigenetic function.
Abstract: A plethora of epigenetic modifications have been described in the human genome and shown to play diverse roles in gene regulation, cellular differentiation and the onset of disease. Although individual modifications have been linked to the activity levels of various genetic functional elements, their combinatorial patterns are still unresolved and their potential for systematic de novo genome annotation remains untapped. Here, we use a multivariate Hidden Markov Model to reveal 'chromatin states' in human T cells, based on recurrent and spatially coherent combinations of chromatin marks. We define 51 distinct chromatin states, including promoter-associated, transcription-associated, active intergenic, large-scale repressed and repeat-associated states. Each chromatin state shows specific enrichments in functional annotations, sequence motifs and specific experimentally observed characteristics, suggesting distinct biological roles. This approach provides a complementary functional annotation of the human genome that reveals the genome-wide locations of diverse classes of epigenetic function.
TL;DR: Over the past four years, several new types of experimental biologic treatment have received commercial registration, but the emergence of biosimilars represents the biggest shift in the biologic approval landscape.
Abstract: Over the past four years, several new types of experimental biologic treatment have received commercial registration, but the emergence of biosimilars represents the biggest shift in the biologic approval landscape.
TL;DR: P predictive models for classifying a sample with respect to one of 13 endpoints indicative of lung or liver toxicity in rodents, or of breast cancer, multiple myeloma or neuroblastoma in humans are generated.
Abstract: Gene expression data from microarrays are being applied to predict preclinical and clinical endpoints, but the reliability of these predictions has not been established. In the MAQC-II project, 36 independent teams analyzed six microarray data sets to generate predictive models for classifying a sample with respect to one of 13 endpoints indicative of lung or liver toxicity in rodents, or of breast cancer, multiple myeloma or neuroblastoma in humans. In total, >30,000 models were built using many combinations of analytical methods. The teams generated predictive models without knowing the biological meaning of some of the endpoints and, to mimic clinical reality, tested the models on data that had not been used for training. We found that model performance depended largely on the endpoint and team proficiency and that different approaches generated models of similar performance. The conclusions and recommendations from MAQC-II should be useful for regulatory agencies, study committees and independent investigators that evaluate methods for global gene expression analysis.
TL;DR: In this paper, the authors show that systemic treatment of tumor-bearing mice with miR-10b antagomirs-a class of chemically modified anti-miRNA oligonucleotide-suppresses breast cancer metastasis.
Abstract: MicroRNAs (miRNAs) are increasingly implicated in the regulation of metastasis. Despite their potential as targets for anti-metastatic therapy, miRNAs have only been silenced in normal tissues of rodents and nonhuman primates. Therefore, the development of effective approaches for sequence-specific inhibition of miRNAs in tumors remains a scientific and clinical challenge. Here we show that systemic treatment of tumor-bearing mice with miR-10b antagomirs-a class of chemically modified anti-miRNA oligonucleotide-suppresses breast cancer metastasis. Both in vitro and in vivo, silencing of miR-10b with antagomirs significantly decreases miR-10b levels and increases the levels of a functionally important miR-10b target, Hoxd10. Administration of miR-10b antagomirs to mice bearing highly metastatic cells does not reduce primary mammary tumor growth but markedly suppresses formation of lung metastases in a sequence-specific manner. The miR-10b antagomir, which is well tolerated by normal animals, appears to be a promising candidate for the development of new anti-metastasis agents.
TL;DR: The presence of multiple epigenetic aberrations within malignant tissue and the abilities of cells to develop resistance suggest that epigenetic therapies are most beneficial when combined with other anticancer strategies, such as signal transduction inhibitors or cytotoxic treatments.
Abstract: Epigenetic modifications work in concert with genetic mechanisms to regulate transcriptional activity in normal tissues and are often dysregulated in disease. Although they are somatically heritable, modifications of DNA and histones are also reversible, making them good targets for therapeutic intervention. Epigenetic changes often precede disease pathology, making them valuable diagnostic indicators for disease risk or prognostic indicators for disease progression. Several inhibitors of histone deacetylation or DNA methylation are approved for hematological malignancies by the US Food and Drug Administration and have been in clinical use for several years. More recently, histone methylation and microRNA expression have gained attention as potential therapeutic targets. The presence of multiple epigenetic aberrations within malignant tissue and the abilities of cells to develop resistance suggest that epigenetic therapies are most beneficial when combined with other anticancer strategies, such as signal transduction inhibitors or cytotoxic treatments. A key challenge for future epigenetic therapies will be to develop inhibitors with specificity to particular regions of chromosomes, thereby potentially reducing side effects.
TL;DR: It is found that success in progression to the blastocyst stage can be predicted with >93% sensitivity and specificity by measuring three dynamic, noninvasive imaging parameters by day 2 after fertilization, before embryonic genome activation (EGA).
Abstract: We report studies of preimplantation human embryo development that correlate time-lapse image analysis and gene expression profiling. By examining a large set of zygotes from in vitro fertilization (IVF), we find that success in progression to the blastocyst stage can be predicted with >93% sensitivity and specificity by measuring three dynamic, noninvasive imaging parameters by day 2 after fertilization, before embryonic genome activation (EGA). These parameters can be reliably monitored by automated image analysis, confirming that successful development follows a set of carefully orchestrated and predictable events. Moreover, we show that imaging phenotypes reflect molecular programs of the embryo and of individual blastomeres. Single-cell gene expression analysis reveals that blastomeres develop cell autonomously, with some cells advancing to EGA and others arresting. These studies indicate that success and failure in human embryo development is largely determined before EGA. Our methods and algorithms may provide an approach for early diagnosis of embryo potential in assisted reproduction.
TL;DR: It is shown that fission yeast has more essential genes than budding yeast and that essential genes are more likely than nonessential genes to be present in a single copy, to be broadly conserved and to contain introns.
Abstract: We report the construction and analysis of 4,836 heterozygous diploid deletion mutants covering 98.4% of the fission yeast genome providing a tool for studying eukaryotic biology. Comprehensive gene dispensability comparisons with budding yeast--the only other eukaryote for which a comprehensive knockout library exists--revealed that 83% of single-copy orthologs in the two yeasts had conserved dispensability. Gene dispensability differed for certain pathways between the two yeasts, including mitochondrial translation and cell cycle checkpoint control. We show that fission yeast has more essential genes than budding yeast and that essential genes are more likely than nonessential genes to be present in a single copy, to be broadly conserved and to contain introns. Growth fitness analyses determined sets of haploinsufficient and haploproficient genes for fission yeast, and comparisons with budding yeast identified specific ribosomal proteins and RNA polymerase subunits, which may act more generally to regulate eukaryotic cell growth.
TL;DR: The demonstration that a minority of CCR5−/− HSPCs can populate an infected animal with HIV-1-resistant, CCR4+/− progeny supports the use of ZFN-modified autologous hematopoietic stem cells as a clinical approach to treating HIV- 1.
Abstract: CCR5 is the major HIV-1 co-receptor, and individuals homozygous for a 32-bp deletion in CCR5 are resistant to infection by CCR5-tropic HIV-1. Using engineered zinc-finger nucleases (ZFNs), we disrupted CCR5 in human CD34(+) hematopoietic stem/progenitor cells (HSPCs) at a mean frequency of 17% of the total alleles in a population. This procedure produces both mono- and bi-allelically disrupted cells. ZFN-treated HSPCs retained the ability to engraft NOD/SCID/IL2rgamma(null) mice and gave rise to polyclonal multi-lineage progeny in which CCR5 was permanently disrupted. Control mice receiving untreated HSPCs and challenged with CCR5-tropic HIV-1 showed profound CD4(+) T-cell loss. In contrast, mice transplanted with ZFN-modified HSPCs underwent rapid selection for CCR5(-/-) cells, had significantly lower HIV-1 levels and preserved human cells throughout their tissues. The demonstration that a minority of CCR5(-/-) HSPCs can populate an infected animal with HIV-1-resistant, CCR5(-/-) progeny supports the use of ZFN-modified autologous hematopoietic stem cells as a clinical approach to treating HIV-1.
TL;DR: In this paper, the introduction of physiologically relevant miRNAs can enhance or modulate somatic cell reprogramming, generating induced pluripotent stem cells (iPS cells).
Abstract: The methods of the present application describe that introduction of physiologically relevant miRNAs can enhance or modulate somatic cell reprogramming, generating induced pluripotent stem cells (iPS cells). These miRNAs did not further enhance reprogramming in the presence of cMyc. Furthermore, unlike previously described methods of generating iPS cells, such as through the introduction of genetic elements using viruses, the methods of the present invention reduce the risk of activating oncogenes in the iPS cells. The methods of the invention generate iPS cells that can be free of genetic modifications and thus have greater potential for use as therapeutic agents than those generated by existing methods.
TL;DR: V3D-Neuron can precisely digitize the morphology of a single neuron in a fruitfly brain in minutes, with about a 17-fold improvement in reliability and tenfold savings in time compared with other neuron reconstruction tools.
Abstract: The V3D system provides three-dimensional (3D) visualization of gigabyte-sized microscopy image stacks in real time on current laptops and desktops V3D streamlines the online analysis, measurement and proofreading of complicated image patterns by combining ergonomic functions for selecting a location in an image directly in 3D space and for displaying biological measurements, such as from fluorescent probes, using the overlaid surface objects V3D runs on all major computer platforms and can be enhanced by software plug-ins to address specific biological problems To demonstrate this extensibility, we built a V3D-based application, V3D-Neuron, to reconstruct complex 3D neuronal structures from high-resolution brain images V3D-Neuron can precisely digitize the morphology of a single neuron in a fruitfly brain in minutes, with about a 17-fold improvement in reliability and tenfold savings in time compared with other neuron reconstruction tools Using V3D-Neuron, we demonstrate the feasibility of building a 3D digital atlas of neurite tracts in the fruitfly brain
Baylor College of Medicine1, Washington University in St. Louis2, University of California, San Francisco3, University of British Columbia4, University of California, Santa Cruz5, University of California, Davis6, Salk Institute for Biological Studies7, Broad Institute8, Harvard University9, Ludwig Institute for Cancer Research10, University of California, San Diego11, University of Texas at Dallas12, Max Planck Society13
TL;DR: This work combined MeDIP-seq with methylation-sensitive restriction enzyme (MRE-seq) sequencing for comprehensive methylome coverage at lower cost and detected regions with allele-specific epigenetic states, identifying most known imprinted regions and new loci with Monoallelic epigenetic marks and monoallelic expression.
Abstract: Analysis of DNA methylation patterns relies increasingly on sequencing-based profiling methods. The four most frequently used sequencing-based technologies are the bisulfite-based methods MethylC-seq and reduced representation bisulfite sequencing (RRBS), and the enrichment-based techniques methylated DNA immunoprecipitation sequencing (MeDIP-seq) and methylated DNA binding domain sequencing (MBD-seq). We applied all four methods to biological replicates of human embryonic stem cells to assess their genome-wide CpG coverage, resolution, cost, concordance and the influence of CpG density and genomic context. The methylation levels assessed by the two bisulfite methods were concordant (their difference did not exceed a given threshold) for 82% for CpGs and 99% of the non-CpG cytosines. Using binary methylation calls, the two enrichment methods were 99% concordant and regions assessed by all four methods were 97% concordant. We combined MeDIP-seq with methylation-sensitive restriction enzyme (MRE-seq) sequencing for comprehensive methylome coverage at lower cost. This, along with RNA-seq and ChIP-seq of the ES cells enabled us to detect regions with allele-specific epigenetic states, identifying most known imprinted regions and new loci with monoallelic epigenetic marks and monoallelic expression.
Memorial Sloan Kettering Cancer Center1, Bilkent University2, SRI International3, Université libre de Bruxelles4, Ontario Institute for Cancer Research5, New York University6, National Institutes of Health7, National Autonomous University of Mexico8, Boston University9, Cold Spring Harbor Laboratory10, Johns Hopkins University11, University of Toronto12, University of Rennes13, Rothamsted Research14, Cell Signaling Technology15, Broad Institute16, Food and Drug Administration17, Virginia Tech18, Oregon Health & Science University19, United States Environmental Protection Agency20, Argonne National Laboratory21, University of Connecticut22, Harvard University23, National Institute of Standards and Technology24, University of Cambridge25, National University of Ireland, Galway26, Konrad Lorenz Institute for Evolution and Cognition Research27, Maastricht University28, University of Auckland29, Syngenta30, Stanford University31, Yale University32, Loyola Marymount University33, St. John's University34, Columbia University35, SRA International36, Novartis37, University of Ottawa38, Vertex Pharmaceuticals39, Medical College of Wisconsin40, Gladstone Institutes41, Cornell University42, Takeda Pharmaceutical Company43, University of Chicago44, Total S.A.45, Kyoto University46, California Institute of Technology47
TL;DR: Thousands of interactions, organized into thousands of pathways, from many organisms are available from a growing number of databases, and this large amount of pathway data in a computable form will support visualization, analysis and biological discovery.
Abstract: Biological Pathway Exchange (BioPAX) is a standard language to represent biological pathways at the molecular and cellular level and to facilitate the exchange of pathway data. The rapid growth of the volume of pathway data has spurred the development of databases and computational tools to aid interpretation; however, use of these data is hampered by the current fragmentation of pathway information across many databases with incompatible formats. BioPAX, which was created through a community process, solves this problem by making pathway data substantially easier to collect, index, interpret and share. BioPAX can represent metabolic and signaling pathways, molecular and genetic interactions and gene regulation networks. Using BioPAX, millions of interactions, organized into thousands of pathways, from many organisms are available from a growing number of databases. This large amount of pathway data in a computable form will support visualization, analysis and biological discovery.
TL;DR: This work uses scAAV9-mediated postnatal day 1 vascular gene delivery to replace SMN in SMA pups and rescue motor function, neuromuscular physiology and life span and demonstrates the clinical potential of scAAv9 gene therapy for SMA.
Abstract: Spinal muscular atrophy (SMA), the most common autosomal recessive neurodegenerative disease affecting children, results in impaired motor neuron function. Despite knowledge of the pathogenic role of decreased survival motor neuron (SMN) protein levels, efforts to increase SMN have not resulted in a treatment for patients. We recently demonstrated that self-complementary adeno-associated virus 9 (scAAV9) can infect approximately 60% of motor neurons when injected intravenously into neonatal mice. Here we use scAAV9-mediated postnatal day 1 vascular gene delivery to replace SMN in SMA pups and rescue motor function, neuromuscular physiology and life span. Treatment on postnatal day 5 results in partial correction, whereas postnatal day 10 treatment has little effect, suggesting a developmental period in which scAAV9 therapy has maximal benefit. Notably, we also show extensive scAAV9-mediated motor neuron transduction after injection into a newborn cynomolgus macaque. This demonstration that scAAV9 traverses the blood-brain barrier in a nonhuman primate emphasizes the clinical potential of scAAV9 gene therapy for SMA.
TL;DR: It is observed that prolonged exposure due to FcRn-mediated enhancement of half-life improved antitumor activity of Fc-engineered antibodies in an hFc Rn/Rag1−/− mouse model, which bridges the demand for dosing convenience with the clinical necessity of maintaining efficacy.
Abstract: Improved affinity for the neonatal Fc receptor (FcRn) is known to extend antibody half-life in vivo. However, this has never been linked with enhanced therapeutic efficacy. We tested whether antibodies with half-lives extended up to fivefold in human (h)FcRn transgenic mice and threefold in cynomolgus monkeys retain efficacy at longer dosing intervals. We observed that prolonged exposure due to FcRn-mediated enhancement of half-life improved antitumor activity of Fc-engineered antibodies in an hFcRn/Rag1(-/-) mouse model. This bridges the demand for dosing convenience with the clinical necessity of maintaining efficacy.
TL;DR: This work considers the three main mass spectrometry (MS)-based proteomic approaches used today: shotgun (or discovery), directed and targeted strategies, and discusses the principles of each technique, their strengths and weaknesses and the dependence of their performance profiles on the composition of the biological sample.
Abstract: The vast majority of proteomic studies to date have relied on mass spectrometric techniques to identify, and in some cases quantify, peptides that have been generated by proteolysis. Current approaches differ in the types of instrument used, their performance profiles, the manner in which they interface with biological research strategies, and their reliance on and use of prior information. Here, we consider the three main mass spectrometry (MS)-based proteomic approaches used today: shotgun (or discovery), directed and targeted strategies. We discuss the principles of each technique, their strengths and weaknesses and the dependence of their performance profiles on the composition of the biological sample. Our goal is to provide a rational framework for selecting strategies optimally suited to address the specific research issue under consideration.
TL;DR: Four methods to map DNA methylation on a genomic scale are benchmarked by analyzing two human embryonic stem cell lines derived from genetically unrelated embryos and a matched pair of colon tumor and adjacent normal colon tissue obtained from the same donor to reveal differences in their ability to detect differentially methylated regions between pairs of samples.
Abstract: DNA methylation plays a key role in regulating eukaryotic gene expression. Although mitotically heritable and stable over time, patterns of DNA methylation frequently change in response to cell differentiation, disease and environmental influences. Several methods have been developed to map DNA methylation on a genomic scale. Here, we benchmark four of these approaches by analyzing two human embryonic stem cell lines derived from genetically unrelated embryos and a matched pair of colon tumor and adjacent normal colon tissue obtained from the same donor. Our analysis reveals that methylated DNA immunoprecipitation sequencing (MeDIP-seq), methylated DNA capture by affinity purification (MethylCap-seq), reduced representation bisulfite sequencing (RRBS) and the Infinium HumanMethylation27 assay all produce accurate DNA methylation data. However, these methods differ in their ability to detect differentially methylated regions between pairs of samples. We highlight strengths and weaknesses of the four methods and give practical recommendations for the design of epigenomic case-control studies.
TL;DR: A multiplexed fluorescent in situ hybridization method based on orthogonal amplification with hybridization chain reactions (HCR), in which RNA probes complementary to mRNA targets trigger chain reactions in which fluorophore-labeled RNA hairpins self-assemble into tethered fluorescent amplification polymers.
Abstract: In situ hybridization methods enable the mapping of mRNA expression within intact biological samples. With current approaches, it is challenging to simultaneously map multiple target mRNAs within whole-mount vertebrate embryos, representing a significant limitation in attempting to study interacting regulatory elements in systems most relevant to human development and disease. Here, we report a multiplexed fluorescent in situ hybridization method based on orthogonal amplification with hybridization chain reactions (HCR). With this approach, RNA probes complementary to mRNA targets trigger chain reactions in which fluorophore-labeled RNA hairpins self-assemble into tethered fluorescent amplification polymers. The programmability and sequence specificity of these amplification cascades enable multiple HCR amplifiers to operate orthogonally at the same time in the same sample. Robust performance is achieved when imaging five target mRNAs simultaneously in fixed whole-mount and sectioned zebrafish embryos. HCR amplifiers exhibit deep sample penetration, high signal-to-background ratios and sharp signal localization.
TL;DR: Urinary Kim-1 measurements may facilitate sensitive, specific and accurate prediction of human nephrotoxicity in preclinical drug screens, which should enable early identification and elimination of compounds that are potentiallyNephrotoxic.
Abstract: Kidney toxicity accounts both for the failure of many drug candidates as well as considerable patient morbidity. Whereas histopathology remains the gold standard for nephrotoxicity in animal systems, serum creatinine (SCr) and blood urea nitrogen (BUN) are the primary options for monitoring kidney dysfunction in humans. The transmembrane tubular protein kidney injury molecule-1 (Kim-1) was previously reported to be markedly induced in response to renal injury. Owing to the poor sensitivity and specificity of SCr and BUN, we used rat toxicology studies to compare the diagnostic performance of urinary Kim-1 to BUN, SCr and urinary N-acetyl-beta-D-glucosaminidase (NAG) as predictors of kidney tubular damage scored by histopathology. Kim-1 outperforms SCr, BUN and urinary NAG in multiple rat models of kidney injury. Urinary Kim-1 measurements may facilitate sensitive, specific and accurate prediction of human nephrotoxicity in preclinical drug screens. This should enable early identification and elimination of compounds that are potentially nephrotoxic.
TL;DR: A xeno-free and feeder-free system for culturing human embryonic stem cells and induced pluripotent stem cells on a recombinant form of human laminin-511, a component of the natural hES cell niche that may be useful for the development of cell lineages for therapeutic purposes.
Abstract: We describe a system for culturing human embryonic stem (hES) cells and induced pluripotent stem (iPS) cells on a recombinant form of human laminin-511, a component of the natural hES cell niche. The system is devoid of animal products and feeder cells and contains only one undefined component, human albumin. The hES cells self-renewed with normal karyotype for at least 4 months (20 passages), after which the cells could produce teratomas containing cell lineages of all three germ layers. When plated on laminin-511 in small clumps, hES cells spread out in a monolayer, maintaining cellular homogeneity with approximately 97% OCT4-positive cells. Adhesion of hES cells was dependent on alpha6beta1 integrin. The use of homogeneous monolayer hES or iPS cell cultures provides more controllable conditions for the design of differentiation methods. This xeno-free and feeder-free system may be useful for the development of cell lineages for therapeutic purposes.