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Cell Systems

Marios Tomazou, Mauricio Barahona, Karen M Polizzi, Guy-Bart Stan
To perform well in biotechnology applications, synthetic genetic oscillators must be engineered to allow independent modulation of amplitude and period. This need is currently unmet. Here, we demonstrate computationally how two classic genetic oscillators, the dual-feedback oscillator and the repressilator, can be re-designed to provide independent control of amplitude and period and improve tunability-that is, a broad dynamic range of periods and amplitudes accessible through the input "dials." Our approach decouples frequency and amplitude modulation by incorporating an orthogonal "sink module" where the key molecular species are channeled for enzymatic degradation...
April 10, 2018: Cell Systems
Lev Litichevskiy, Ryan Peckner, Jennifer G Abelin, Jacob K Asiedu, Amanda L Creech, John F Davis, Desiree Davison, Caitlin M Dunning, Jarrett D Egertson, Shawn Egri, Joshua Gould, Tak Ko, Sarah A Johnson, David L Lahr, Daniel Lam, Zihan Liu, Nicholas J Lyons, Xiaodong Lu, Brendan X MacLean, Alison E Mungenast, Adam Officer, Ted E Natoli, Malvina Papanastasiou, Jinal Patel, Vagisha Sharma, Courtney Toder, Andrew A Tubelli, Jennie Z Young, Steven A Carr, Todd R Golub, Aravind Subramanian, Michael J MacCoss, Li-Huei Tsai, Jacob D Jaffe
Although the value of proteomics has been demonstrated, cost and scale are typically prohibitive, and gene expression profiling remains dominant for characterizing cellular responses to perturbations. However, high-throughput sentinel assays provide an opportunity for proteomics to contribute at a meaningful scale. We present a systematic library resource (90 drugs × 6 cell lines) of proteomic signatures that measure changes in the reduced-representation phosphoproteome (P100) and changes in epigenetic marks on histones (GCP)...
April 10, 2018: Cell Systems
Simon van Vliet, Alma Dal Co, Annina R Winkler, Stefanie Spriewald, Bärbel Stecher, Martin Ackermann
Gene expression levels in clonal bacterial groups have been found to be spatially correlated. These correlations can partly be explained by the shared lineage history of nearby cells, although they could also arise from local cell-cell interactions. Here, we present a quantitative framework that allows us to disentangle the contributions of lineage history, long-range spatial gradients, and local cell-cell interactions to spatial correlations in gene expression. We study pathways involved in toxin production, SOS stress response, and metabolism in Escherichia coli microcolonies and find for all pathways that shared lineage history is the main cause of spatial correlations in gene expression levels...
April 5, 2018: Cell Systems
Ning Shen, Jingkang Zhao, Joshua L Schipper, Yuning Zhang, Tristan Bepler, Dan Leehr, John Bradley, John Horton, Hilmar Lapp, Raluca Gordan
Paralogous transcription factors (TFs) are oftentimes reported to have identical DNA-binding motifs, despite the fact that they perform distinct regulatory functions. Differential genomic targeting by paralogous TFs is generally assumed to be due to interactions with protein co-factors or the chromatin environment. Using a computational-experimental framework called iMADS (integrative modeling and analysis of differential specificity), we show that, contrary to previous assumptions, paralogous TFs bind differently to genomic target sites even in vitro...
March 28, 2018: Cell Systems
Justin K Huang, Daniel E Carlin, Michael Ku Yu, Wei Zhang, Jason F Kreisberg, Pablo Tamayo, Trey Ideker
Gene networks are rapidly growing in size and number, raising the question of which networks are most appropriate for particular applications. Here, we evaluate 21 human genome-wide interaction networks for their ability to recover 446 disease gene sets identified through literature curation, gene expression profiling, or genome-wide association studies. While all networks have some ability to recover disease genes, we observe a wide range of performance with STRING, ConsensusPathDB, and GIANT networks having the best performance overall...
March 26, 2018: Cell Systems
Stéphane Chevrier, Helena L Crowell, Vito R T Zanotelli, Stefanie Engler, Mark D Robinson, Bernd Bodenmiller
The advent of mass cytometry increased the number of parameters measured at the single-cell level while decreasing the extent of crosstalk between channels relative to dye-based flow cytometry. Although reduced, spillover still exists in mass cytometry data, and minimizing its effect requires considerable expert knowledge and substantial experimental effort. Here, we describe a novel bead-based compensation workflow and R-based software that estimates and corrects for interference between channels. We performed an in-depth characterization of the spillover properties in mass cytometry, including limitations defined by the linear range of the mass cytometer and the reproducibility of the spillover over time and across machines...
March 23, 2018: Cell Systems
Manuel Razo-Mejia, Stephanie L Barnes, Nathan M Belliveau, Griffin Chure, Tal Einav, Mitchell Lewis, Rob Phillips
Allosteric regulation is found across all domains of life, yet we still lack simple, predictive theories that directly link the experimentally tunable parameters of a system to its input-output response. To that end, we present a general theory of allosteric transcriptional regulation using the Monod-Wyman-Changeux model. We rigorously test this model using the ubiquitous simple repression motif in bacteria by first predicting the behavior of strains that span a large range of repressor copy numbers and DNA binding strengths and then constructing and measuring their response...
March 16, 2018: Cell Systems
Ruben Perez-Carrasco, Chris P Barnes, Yolanda Schaerli, Mark Isalan, James Briscoe, Karen M Page
Although the structure of a genetically encoded regulatory circuit is an important determinant of its function, the relationship between circuit topology and the dynamical behaviors it can exhibit is not well understood. Here, we explore the range of behaviors available to the AC-DC circuit. This circuit consists of three genes connected as a combination of a toggle switch and a repressilator. Using dynamical systems theory, we show that the AC-DC circuit exhibits both oscillations and bistability within the same region of parameter space; this generates emergent behaviors not available to either the toggle switch or the repressilator alone...
March 12, 2018: Cell Systems
Max V Staller, Alex S Holehouse, Devjanee Swain-Lenz, Rahul K Das, Rohit V Pappu, Barak A Cohen
Transcriptional activation domains are essential for gene regulation, but their intrinsic disorder and low primary sequence conservation have made it difficult to identify the amino acid composition features that underlie their activity. Here, we describe a rational mutagenesis scheme that deconvolves the function of four activation domain sequence features-acidity, hydrophobicity, intrinsic disorder, and short linear motifs-by quantifying the activity of thousands of variants in vivo and simulating their conformational ensembles using an all-atom Monte Carlo approach...
March 1, 2018: Cell Systems
Kevin Thurley, Lani F Wu, Steven J Altschuler
Cell-to-cell communication networks have critical roles in coordinating diverse organismal processes, such as tissue development or immune cell response. However, compared with intracellular signal transduction networks, the function and engineering principles of cell-to-cell communication networks are far less understood. Major complications include: cells are themselves regulated by complex intracellular signaling networks; individual cells are heterogeneous; and output of any one cell can recursively become an additional input signal to other cells...
February 23, 2018: Cell Systems
Spencer S Watson, Mark Dane, Koei Chin, Zuzana Tatarova, Moqing Liu, Tiera Liby, Wallace Thompson, Rebecca Smith, Michel Nederlof, Elmar Bucher, David Kilburn, Matthew Whitman, Damir Sudar, Gordon B Mills, Laura M Heiser, Oliver Jonas, Joe W Gray, James E Korkola
Extrinsic signals are implicated in breast cancer resistance to HER2-targeted tyrosine kinase inhibitors (TKIs). To examine how microenvironmental signals influence resistance, we monitored TKI-treated breast cancer cell lines grown on microenvironment microarrays composed of printed extracellular matrix proteins supplemented with soluble proteins. We tested ∼2,500 combinations of 56 soluble and 46 matrix microenvironmental proteins on basal-like HER2+ (HER2E) or luminal-like HER2+ (L-HER2+) cells treated with the TKIs lapatinib or neratinib...
February 21, 2018: Cell Systems
Congxin Li, François Cesbron, Michael Oehler, Michael Brunner, Thomas Höfer
Gene regulation is a complex non-equilibrium process. Here, we show that quantitating the temporal regulation of key gene states (transcriptionally inactive, active, and refractory) provides a parsimonious framework for analyzing gene regulation. Our theory makes two non-intuitive predictions. First, for transcription factors (TFs) that regulate transcription burst frequency, as opposed to amplitude or duration, weak TF binding is sufficient to elicit strong transcriptional responses. Second, refractoriness of a gene after a transcription burst enables rapid responses to stimuli...
February 12, 2018: Cell Systems
Eduardo Torre, Hannah Dueck, Sydney Shaffer, Janko Gospocic, Rohit Gupte, Roberto Bonasio, Junhyong Kim, John Murray, Arjun Raj
Although single-cell RNA sequencing can reliably detect large-scale transcriptional programs, it is unclear whether it accurately captures the behavior of individual genes, especially those that express only in rare cells. Here, we use single-molecule RNA fluorescence in situ hybridization as a gold standard to assess trade-offs in single-cell RNA-sequencing data for detecting rare cell expression variability. We quantified the gene expression distribution for 26 genes that range from ubiquitous to rarely expressed and found that the correspondence between estimates across platforms improved with both transcriptome coverage and increased number of cells analyzed...
February 7, 2018: Cell Systems
Peng Jiang, Winston Lee, Xujuan Li, Carl Johnson, Jun S Liu, Myles Brown, Jon Christopher Aster, X Shirley Liu
Identifying reliable drug response biomarkers is a significant challenge in cancer research. We present computational analysis of resistance (CARE), a computational method focused on targeted therapies, to infer genome-wide transcriptomic signatures of drug efficacy from cell line compound screens. CARE outputs genome-scale scores to measure how the drug target gene interacts with other genes to affect the inhibitor efficacy in the compound screens. Such statistical interactions between drug targets and other genes were not considered in previous studies but are critical in identifying predictive biomarkers...
February 6, 2018: Cell Systems
James T Robinson, Douglass Turner, Neva C Durand, Helga Thorvaldsdóttir, Jill P Mesirov, Erez Lieberman Aiden
Contact mapping experiments such as Hi-C explore how genomes fold in 3D. Here, we introduce Juicebox.js, a cloud-based web application for exploring the resulting datasets. Like the original Juicebox application, Juicebox.js allows users to zoom in and out of such datasets using an interface similar to Google Earth. Juicebox.js also has many features designed to facilitate data reproducibility and sharing. Furthermore, Juicebox.js encodes the exact state of the browser in a shareable URL. Creating a public browser for a new Hi-C dataset does not require coding and can be accomplished in under a minute...
February 5, 2018: Cell Systems
Steve O'Hagan, Marina Wright Muelas, Philip J Day, Emma Lundberg, Douglas B Kell
The expression levels of SLC or ABC membrane transporter transcripts typically differ 100- to 10,000-fold between different tissues. The Gini coefficient characterizes such inequalities and here is used to describe the distribution of the expression of each transporter among different human tissues and cell lines. Many transporters exhibit extremely high Gini coefficients even for common substrates, indicating considerable specialization consistent with divergent evolution. The expression profiles of SLC transporters in different cell lines behave similarly, although Gini coefficients for ABC transporters tend to be larger in cell lines than in tissues, implying selection...
February 5, 2018: Cell Systems
Elisa Donnard, Pranitha Vangala, Shaked Afik, Sean McCauley, Anetta Nowosielska, Alper Kucukural, Barbara Tabak, Xiaopeng Zhu, William Diehl, Patrick McDonel, Nir Yosef, Jeremy Luban, Manuel Garber
Most well-characterized enhancers are deeply conserved. In contrast, genome-wide comparative studies of steady-state systems showed that only a small fraction of active enhancers are conserved. To better understand conservation of enhancer activity, we used a comparative genomics approach that integrates temporal expression and epigenetic profiles in an innate immune system. We found that gene expression programs diverge among mildly induced genes, while being highly conserved for strongly induced genes. The fraction of conserved enhancers varies greatly across gene expression programs, with induced genes and early-response genes, in particular, being regulated by a higher fraction of conserved enhancers...
January 30, 2018: Cell Systems
Stephanie A Zlatic, Alysia Vrailas-Mortimer, Avanti Gokhale, Lucas J Carey, Elizabeth Scott, Reid Burch, Morgan M McCall, Samantha Rudin-Rush, John Bowen Davis, Cortnie Hartwig, Erica Werner, Lian Li, Michael Petris, Victor Faundez
Rare neurological diseases shed light onto universal neurobiological processes. However, molecular mechanisms connecting genetic defects to their disease phenotypes are elusive. Here, we obtain mechanistic information by comparing proteomes of cells from individuals with rare disorders with proteomes from their disease-free consanguineous relatives. We use triple-SILAC mass spectrometry to quantify proteomes from human pedigrees affected by mutations in ATP7A, which cause Menkes disease, a rare neurodegenerative and neurodevelopmental disorder stemming from systemic copper depletion...
January 30, 2018: Cell Systems
Jin Park, Marta Dies, Yihan Lin, Sahand Hormoz, Stephanie E Smith-Unna, Sofia Quinodoz, María Jesús Hernández-Jiménez, Jordi Garcia-Ojalvo, James C W Locke, Michael B Elowitz
In cells, specific regulators often compete for limited amounts of a core enzymatic resource. It is typically assumed that competition leads to partitioning of core enzyme molecules among regulators at constant levels. Alternatively, however, different regulatory species could time share, or take turns utilizing, the core resource. Using quantitative time-lapse microscopy, we analyzed sigma factor activity dynamics, and their competition for RNA polymerase, in individual Bacillus subtilis cells under energy stress...
January 29, 2018: Cell Systems
Franz X Schaub, Varsha Dhankani, Ashton C Berger, Mihir Trivedi, Anne B Richardson, Reid Shaw, Wei Zhao, Xiaoyang Zhang, Andrea Ventura, Yuexin Liu, Donald E Ayer, Peter J Hurlin, Andrew D Cherniack, Robert N Eisenman, Brady Bernard, Carla Grandori
Although the MYC oncogene has been implicated in cancer, a systematic assessment of alterations of MYC, related transcription factors, and co-regulatory proteins, forming the proximal MYC network (PMN), across human cancers is lacking. Using computational approaches, we define genomic and proteomic features associated with MYC and the PMN across the 33 cancers of The Cancer Genome Atlas. Pan-cancer, 28% of all samples had at least one of the MYC paralogs amplified. In contrast, the MYC antagonists MGA and MNT were the most frequently mutated or deleted members, proposing a role as tumor suppressors...
March 28, 2018: Cell Systems
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