PubMed Central (PMC3 - NLM DTD)
Archive of life sciences journal literature at the U.S. National Institutes of Health (NIH), developed and managed by NIH's National Center for Biotechnology Information (NCBI) in the National Library of Medicine (NLM).
Briefings in Functional Genomics
Mostrando recursos 1 - 20 de 54
Using protein-binding microarrays to study transcription factor specificity: homologs, isoforms and complexes - Andrilenas, Kellen K.; Penvose, Ashley; Siggers, Trevor
Protein–DNA binding is central to specificity in gene regulation, and methods for characterizing transcription factor (TF)–DNA binding remain crucial to studies of regulatory specificity. High-throughput (HT) technologies have revolutionized our ability to characterize protein–DNA binding by significantly increasing the number of binding measurements that can be performed. Protein-binding microarrays (PBMs) are a robust and powerful HT platform for studying DNA-binding specificity of TFs. Analysis of PBM-determined DNA-binding profiles has provided new insight into the scope and mechanisms of TF binding diversity. In this review, we focus specifically on the PBM technique and discuss its application to the study of TF...
Structure-based modeling of protein: DNA specificity - Joyce, Adam P.; Zhang, Chi; Bradley, Philip; Havranek, James J.
Protein:DNA interactions are essential to a range of processes that maintain and express the information encoded in the genome. Structural modeling is an approach that aims to understand these interactions at the physicochemical level. It has been proposed that structural modeling can lead to deeper understanding of the mechanisms of protein:DNA interactions, and that progress in this field can not only help to rationalize the observed specificities of DNA-binding proteins but also to allow researchers to engineer novel DNA site specificities. In this review we discuss recent developments in the structural description of protein:DNA interactions and specificity, as well as...
Spec-seq: determining protein–DNA-binding specificity by sequencing - Stormo, Gary D.; Zuo, Zheng; Chang, Yiming Kenny
The specificity of protein–DNA interactions can be determined directly by sequencing the bound and unbound fractions in a standard binding reaction. The procedure is easy and inexpensive, and the accuracy can be high for thousands of sequences assayed in parallel. From the measurements, simple models of specificity, such as position weight matrices, can be assessed for their accuracy and more complex models developed if useful. Those may provide more accurate predictions of in vivo binding sites and can help us to understand the details of recognition. As an example, we demonstrate new information gained about the binding of lac repressor....
Functional roles of nucleosome stability and dynamics - Chereji, Răzvan V.; Morozov, Alexandre V.
Nucleosome is a histone–DNA complex known as the fundamental repeating unit of chromatin. Up to 90% of eukaryotic DNA is wrapped around consecutive octamers made of the core histones H2A, H2B, H3 and H4. Nucleosome positioning affects numerous cellular processes that require robust and timely access to genomic DNA, which is packaged into the tight confines of the cell nucleus. In living cells, nucleosome positions are determined by intrinsic histone–DNA sequence preferences, competition between histones and other DNA-binding proteins for genomic sequence, and ATP-dependent chromatin remodelers. We discuss the major energetic contributions to nucleosome formation and remodeling, focusing especially on...
Event-based text mining for biology and functional genomics - Ananiadou, Sophia; Thompson, Paul; Nawaz, Raheel; McNaught, John; Kell, Douglas B.
The assessment of genome function requires a mapping between genome-derived entities and biochemical reactions, and the biomedical literature represents a rich source of information about reactions between biological components. However, the increasingly rapid growth in the volume of literature provides both a challenge and an opportunity for researchers to isolate information about reactions of interest in a timely and efficient manner. In response, recent text mining research in the biology domain has been largely focused on the identification and extraction of ‘events’, i.e. categorised, structured representations of relationships between biochemical entities, from the literature. Functional genomics analyses necessarily encompass events...
Biochemical and bioinformatic methods for elucidating the role of RNA–protein interactions in posttranscriptional regulation - Kloetgen, Andreas; Münch, Philipp C.; Borkhardt, Arndt; Hoell, Jessica I.; McHardy, Alice C.
Our understanding of transcriptional gene regulation has dramatically increased over the past decades, and many regulators of gene expression, such as transcription factors, have been analyzed extensively. Additionally, in recent years, deeper insights into the physiological roles of RNA have been obtained. More precisely, splicing, polyadenylation, various modifications, localization and the translation of messenger RNAs (mRNAs) are regulated by their interaction with RNA-binding proteins (RBPs). New technologies now enable the analysis of this regulation at different levels. A technique known as ultraviolet (UV) cross-linking and immunoprecipitation (CLIP) allows us to determine physical protein–RNA interactions on a genome-wide scale. UV cross-linking...
High-throughput characterization of protein–RNA interactions - Cook, Kate B.; Hughes, Timothy R.; Morris, Quaid D.
RNA-binding proteins (RBPs) are important regulators of eukaryotic gene expression. Genomes typically encode dozens to hundreds of proteins containing RNA-binding domains, which collectively recognize diverse RNA sequences and structures. Recent advances in high-throughput methods for assaying the targets of RBPs in vitro and in vivo allow large-scale derivation of RNA-binding motifs as well as determination of RNA–protein interactions in living cells. In parallel, many computational methods have been developed to analyze and interpret these data. The interplay between RNA secondary structure and RBP binding has also been a growing theme. Integrating RNA–protein interaction data with observations of post-transcriptional regulation will...
Evolving insights on how cytosine methylation affects protein–DNA binding - Dantas Machado, Ana Carolina; Zhou, Tianyin; Rao, Satyanarayan; Goel, Pragya; Rastogi, Chaitanya; Lazarovici, Allan; Bussemaker, Harmen J.; Rohs, Remo
Many anecdotal observations exist of a regulatory effect of DNA methylation on gene expression. However, in general, the underlying mechanisms of this effect are poorly understood. In this review, we summarize what is currently known about how this important, but mysterious, epigenetic mark impacts cellular functions. Cytosine methylation can abrogate or enhance interactions with DNA-binding proteins, or it may have no effect, depending on the context. Despite being only a small chemical change, the addition of a methyl group to cytosine can affect base readout via hydrophobic contacts in the major groove and shape readout via electrostatic contacts in the...
Mutagenesis and phenotyping resources in zebrafish for studying development and human disease - Varshney, Gaurav Kumar; Burgess, Shawn Michael
The zebrafish (Danio rerio) is an important model organism for studying development and human disease. The zebrafish has an excellent reference genome and the functions of hundreds of genes have been tested using both forward and reverse genetic approaches. Recent years have seen an increasing number of large-scale mutagenesis projects and the number of mutants or gene knockouts in zebrafish has increased rapidly, including for the first time conditional knockout technologies. In addition, targeted mutagenesis techniques such as zinc finger nucleases, transcription activator-like effector nucleases and clustered regularly interspaced short sequences (CRISPR) or CRISPR-associated (Cas), have all been shown to...
Heart genetics in a small package, exploiting the condensed genome of Ciona intestinalis - Cota, Christina D.; Segade, Fernando; Davidson, Brad
Defects in the initial establishment of cardiogenic cell fate are likely to contribute to pervasive human congenital cardiac abnormalities. However, the molecular underpinnings of nascent cardiac fate induction have proven difficult to decipher. In this review we explore the participation of extracellular, cellular and nuclear factors in comprehensive specification networks. At each level, we elaborate on insights gained through the study of cardiogenesis in the invertebrate chordate Ciona intestinalis and propose productive lines of future research. In-depth discussion of pre-cardiac induction is intended to serve as a paradigm, illustrating the potential use of Ciona to elucidate comprehensive networks underlying additional...
Epigenetic mechanisms and developmental choice hierarchies in T-lymphocyte development - Rothenberg, Ellen V.
Three interlocking problems in gene regulation are: how to explain genome-wide targeting of transcription factors in different cell types, how prior transcription factor action can establish an ‘epigenetic state’ that changes the options for future transcription factor action, and how directly a sequence of developmental decisions can be memorialized in a hierarchy of repression structures applied to key genes of the ‘paths not taken’. This review uses the finely staged process of T-cell lineage commitment as a test case in which to examine how changes in developmental status are reflected in changes in transcription factor expression, transcription factor binding distribution...
Genomic approaches in breast cancer research - Donahue, Henry J.; Genetos, Damian C.
Microarray technologies provide high-throughput analysis of genes that are differentially expressed in humans and other species, and thereby provide a means to measure how biological systems are altered during development or disease states. Within, we review how high-throughput genomic technologies have increased our understanding about the molecular complexity of breast cancer, identified distinct molecular phenotypes and how they can be used to increase the accuracy of predicted clinical outcome.
Dynamics of the DNA damage response: insights from live-cell imaging - Karanam, Ketki; Loewer, Alexander; Lahav, Galit
All organisms have to safeguard the integrity of their genome to prevent malfunctioning and oncogenic transformation. Sophisticated DNA damage response mechanisms have evolved to detect and repair genomic lesions. With the emergence of live-cell microscopy of individual cells, we now begin to appreciate the complex spatiotemporal kinetics of the DNA damage response and can address the causes and consequences of the heterogeneity in the responses of genetically identical cells. Here, we highlight key discoveries where live-cell imaging has provided unprecedented insights into how cells respond to DNA double-strand breaks and discuss the main challenges and promises in using this technique.
Turning single cells into microarrays by super-resolution barcoding - Cai, Long
In this review, we discuss a strategy to bring genomics and proteomics into single cells by super-resolution microscopy. The basis for this new approach are the following: given the 10 nm resolution of a super-resolution microscope and a typical cell with a size of (10 µm)3, individual cells contain effectively 109 super-resolution pixels or bits of information. Most eukaryotic cells have 104 genes and cellular abundances of 10–100 copies per transcript. Thus, under a super-resolution microscope, an individual cell has 1000 times more pixel volume or information capacities than is needed to encode all transcripts within that cell. Individual species of mRNA...
Interpreting the regulatory genome: the genomics of transcription factor function in Drosophila melanogaster - Slattery, Matthew; Nègre, Nicolas; White, Kevin P.
Researchers have now had access to the fully sequenced Drosophila melanogaster genome for over a decade, and the sequenced genomes of 11 additional Drosophila species have been available for almost 5 years, with more species’ genomes becoming available every year [Adams MD, Celniker SE, Holt RA, et al. The genome sequence of Drosophila melanogaster. Science 2000;287:2185–95; Clark AG, Eisen MB, Smith DR, et al. Evolution of genes and genomes on the Drosophila phylogeny. Nature 2007;450:203–18]. Although the best studied of the D. melanogaster transcription factors (TFs) were cloned before sequencing of the genome, the availability of sequence data promised to...
Genomics of sex determination in Drosophila - Clough, Emily; Oliver, Brian
Drosophilists have identified many, or perhaps most, of the key regulatory genes determining sex using classical genetics, however, regulatory genes must ultimately result in the deployment of the genome in a quantitative manner, replete with complex interactions with other regulatory pathways. In the last decade, genomics has provided a rich picture of the transcriptional profile of the sexes that underlies sexual dimorphism. The current challenge is linking transcriptional profiles with the regulatory genes. This will be a complex synthesis, but the prospects for progress are outstanding.
WRAD: enabler of the SET1-family of H3K4 methyltransferases - Ernst, Patricia; Vakoc, Christopher R.
Methylation of histone H3 at lysine 4 (H3K4) is a conserved feature of active chromatin catalyzed by methyltransferases of the SET1-family (SET1A, SET1B, MLL1, MLL2, MLL3 and MLL4 in humans). These enzymes participate in diverse gene regulatory networks with a multitude of known biological functions, including direct involvement in several human disease states. Unlike most lysine methyltransferases, SET1-family enzymes are only fully active in the context of a multi-subunit complex, which includes a protein module comprised of WDR5, RbBP5, ASH2L and DPY-30 (WRAD). These proteins bind in close proximity to the catalytic SET domain of SET1-family enzymes and stimulate H3K4...
The amphioxus genome provides unique insight into the evolution of immunity - Dishaw, Larry J.; Haire, Robert N.; Litman, Gary W.
Immune systems evolve as essential strategies to maintain homeostasis with the environment, prevent microbial assault and recycle damaged host tissues. The immune system is composed of two components, innate and adaptive immunity. The former is common to all animals while the latter consists of a vertebrate-specific system that relies on somatically derived lymphocytes and is associated with near limitless genetic diversity as well as long-term memory. Deuterostome invertebrates provide a view of immune repertoires in phyla that immediately predate the origins of vertebrates. Genomic studies in amphioxus, a cephalochordate, have revealed homologs of genes encoding most innate immune receptors found...
An integrative functional genomics approach for discovering biomarkers in schizophrenia - Vawter, Marquis P.; Mamdani, Firoza; Macciardi, Fabio
Schizophrenia (SZ) is a complex disorder resulting from both genetic and environmental causes with a lifetime prevalence world-wide of 1%; however, there are no specific, sensitive and validated biomarkers for SZ. A general unifying hypothesis has been put forward that disease-associated single nucleotide polymorphisms (SNPs) from genome-wide association study (GWAS) are more likely to be associated with gene expression quantitative trait loci (eQTL). We will describe this hypothesis and review primary methodology with refinements for testing this paradigmatic approach in SZ. We will describe biomarker studies of SZ and testing enrichment of SNPs that are associated both with eQTLs and...
Targeted enrichment of genomic DNA regions for next-generation sequencing - Mertes, Florian; ElSharawy, Abdou; Sauer, Sascha; van Helvoort, Joop M.L.M.; van der Zaag, P.J.; Franke, Andre; Nilsson, Mats; Lehrach, Hans; Brookes, Anthony J.
In this review, we discuss the latest targeted enrichment methods and aspects of their utilization along with second-generation sequencing for complex genome analysis. In doing so, we provide an overview of issues involved in detecting genetic variation, for which targeted enrichment has become a powerful tool. We explain how targeted enrichment for next-generation sequencing has made great progress in terms of methodology, ease of use and applicability, but emphasize the remaining challenges such as the lack of even coverage across targeted regions. Costs are also considered versus the alternative of whole-genome sequencing which is becoming ever more affordable. We conclude...