Browsing by Author "Garner, Harold R."

Now showing 1 - 20 of 25
  • Thumbnail Image
    BioFlow: a web based workflow management software for design and execution of genomics pipelines
    Garner, Harold R.; Puthige, Ashwin (2014-09-18)
    Background Bioinformatics data analysis is usually done sequentially by chaining together multiple tools. These are created by writing scripts and tracking the inputs and outputs of all stages. Writing such scripts require programming skills. Executing multiple pipelines in parallel and keeping track of all the generated files is difficult and error prone. Checking results and task completion requires users to remotely login to their servers and run commands to identify process status. Users would benefit from a web-based tool that allows creation and execution of pipelines remotely. The tool should also keep track of all the files generated and maintain a history of user activities. Results A software tool for building and executing workflows is described here. The individual tools in the workflows can be any command line executable or script. The software has an intuitive mechanism for adding new tools to be used in workflows. It contains a workflow designer where workflows can be creating by visually connecting various components. Workflows are executed by job runners. The outputs and the job history are saved. The tool is web based software tool and all actions can be performed remotely. Conclusions Users without scripting knowledge can utilize the tool to build pipelines for executing tasks. Pipelines can be modeled as workflows that are reusable. BioFlow enables users to easily add new tools to the database. The workflows can be created and executed remotely. A number of parallel jobs can be easily controlled. Distributed execution is possible by running multiple instances of the application. Any number of tasks can be executed and the output will be stored making it is easy to correlate the outputs to the jobs executed.
  • Thumbnail Image
    Brucella melitensis VjbR and C12-HSL regulons: contributions of the N-dodecanoyl homoserine lactone signaling molecule and LuxR homologue VjbR to gene expression
    Weeks, Jenni N.; Galindo, Cristi L.; Drake, Kenneth L.; Adams, L. Garry; Garner, Harold R.; Ficht, Thomas A. (2010-06-08)
    Background Quorum sensing is a communication system that regulates gene expression in response to population density and often regulates virulence determinants. Deletion of the luxR homologue vjbR highly attenuates intracellular survival of Brucella melitensis and has been interpreted to be an indication of a role for QS in Brucella infection. Confirmation for such a role was suggested, but not confirmed, by the demonstrated in vitro synthesis of an auto-inducer (AI) by Brucella cultures. In an effort to further delineate the role of VjbR to virulence and survival, gene expression under the control of VjbR and AI was characterized using microarray analysis. Results Analyses of wildtype B. melitensis and isogenic ΔvjbR transciptomes, grown in the presence and absence of exogenous N-dodecanoyl homoserine lactone (C12-HSL), revealed a temporal pattern of gene regulation with variances detected at exponential and stationary growth phases. Comparison of VjbR and C12-HSL transcriptomes indicated the shared regulation of 127 genes with all but 3 genes inversely regulated, suggesting that C12-HSL functions via VjbR in this case to reverse gene expression at these loci. Additional analysis using a ΔvjbR mutant revealed that AHL also altered gene expression in the absence of VjbR, up-regulating expression of 48 genes and a luxR homologue blxR 93-fold at stationary growth phase. Gene expression alterations include previously un-described adhesins, proteases, antibiotic and toxin resistance genes, stress survival aids, transporters, membrane biogenesis genes, amino acid metabolism and transport, transcriptional regulators, energy production genes, and the previously reported fliF and virB operons. Conclusions VjbR and C12-HSL regulate expression of a large and diverse number of genes. Many genes identified as virulence factors in other bacterial pathogens were found to be differently expressed, suggesting an important contribution to intracellular survival of Brucella. From these data, we conclude that VjbR and C12-HSL contribute to virulence and survival by regulating expression of virulence mechanisms and thus controlling the ability of the bacteria to survive within the host cell. A likely scenario occurs via QS, however, operation of such a mechanism remains to be demonstrated.
  • Thumbnail Image
    CAGm: A repository of germline microsatellite variations in the 1000 genomes project
    Kinney, N.; Titus-Glover, K.; Wren, J.D.; Varghese, Ronnie; Michalak, Pawel; Liao, H.; Anandakrishnan, Ramu; Pulenthiran, A.; Kang, L.; Garner, Harold R. (Oxford University Press, 2019-01-08)
    The human genome harbors an abundance of repetitive DNA; however, its function continues to be debated. Microsatellites-a class of short tandem repeat-are established as an important source of genetic variation. Array length variants are common among microsatellites and affect gene expression; but, efforts to understand the role and diversity of microsatellite variation has been hampered by several challenges. Without adequate depth, both long-read and short-read sequencing may not detect the variants present in a sample; additionally, large sample sizes are needed to reveal the degree of population-level polymorphism. To address these challenges we present the Comparative Analysis of Germline Microsatellites (CAGm): A database of germline microsatellites from 2529 individuals in the 1000 genomes project. A key novelty of CAGm is the ability to aggregate microsatellite variation by population, ethnicity (super population) and gender. The database provides advanced searching for microsatellites embedded in genes and functional elements. All data can be downloaded as Microsoft Excel spreadsheets. Two use-case scenarios are presented to demonstrate its utility: A mononucleotide (A) microsatellite at the BAT-26 locus and a dinucleotide (CA) microsatellite in the coding region of FGFRL1. CAGm is freely available at http://www.cagmdb.org/. © The Author(s) 2018. Published by Oxford University Press on behalf of Nucleic Acids Research.
  • Thumbnail Image
    Characterizing the Genetic Basis for Nicotine Induced Cancer Development: A Transcriptome Sequencing Study
    Bavarva, Jasmin H.; Tae, Hongseok; Settlage, Robert E.; Garner, Harold R. (PLOS, 2013-06-18)
    Nicotine is a known risk factor for cancer development and has been shown to alter gene expression in cells and tissue upon exposure. We used Illumina® Next Generation Sequencing (NGS) technology to gain unbiased biological insight into the transcriptome of normal epithelial cells (MCF-10A) to nicotine exposure. We generated expression data from 54,699 transcripts using triplicates of control and nicotine stressed cells. As a result, we identified 138 differentially expressed transcripts, including 39 uncharacterized genes. Additionally, 173 transcripts that are primarily associated with DNA replication, recombination, and repair showed evidence for alternative splicing. We discovered the greatest nicotine stress response by HPCAL4 (up-regulated by 4.71 fold) and NPAS3 (down-regulated by -2.73 fold); both are genes that have not been previously implicated in nicotine exposure but are linked to cancer. We also discovered significant down-regulation (-2.3 fold) and alternative splicing of NEAT1 (lncRNA) that may have an important, yet undiscovered regulatory role. Gene ontology analysis revealed nicotine exposure influenced genes involved in cellular and metabolic processes. This study reveals previously unknown consequences of nicotine stress on the transcriptome of normal breast epithelial cells and provides insight into the underlying biological influence of nicotine on normal cells, marking the foundation for future studies.
  • Thumbnail Image
    Comparative Analyses of Transcriptional Profiles in Mouse Organs Using a Pneumonic Plague Model after Infection with Wild-Type Yersinia pestis CO92 and Its Braun Lipoprotein Mutant
    Galindo, Cristi L.; Moen, Scott T.; Kozlova, Elena V.; Sha, Jian; Garner, Harold R.; Agar, Stacy L.; Chopra, Ashok K. (Hindawi, 2010-01-20)
    We employed Murine GeneChips to delineate the global transcriptional profiles of the livers, lungs, and spleens in a mouse pneumonic plague infection model with wild-type (WT) Y. pestis CO92 and its Braun lipoprotein () mutant with reduced virulence. These organs showed differential transcriptional responses to infection with WT Y. pestis, but the overall host functional processes affected were similar across all three tissues. Gene expression alterations were found in inflammation, cytokine signaling, and apoptotic cell death-associated genes. Comparison of WT and mutant-infected mice indicated significant overlap in lipopolysaccharide- (LPS-) associated gene expression, but the absence of Lpp perturbed host cell signaling at critical regulatory junctions resulting in altered immune response and possibly host cell apoptosis. We generated a putative signaling pathway including major inflammatory components that could account for the synergistic action of LPS and Lpp and provided the mechanistic basis of attenuation caused by deletion of the lpp gene from Y. pestis in a mouse model of pneumonic plague.
  • Thumbnail Image
    Comparative Global Gene Expression Profiles of Wild-Type Yersinia pestis CO92 and Its Braun Lipoprotein Mutant at Flea and Human Body Temperatures
    Galindo, Cristi L.; Sha, Jian; Moen, Scott T.; Agar, Stacy L.; Kirtley, Michelle L.; Foltz, Sheri M.; McIver, Lauren J.; Kozlova, E. V.; Garner, Harold R.; Chopra, Ashok K. (Hindawi, 2010-05-19)
    Braun/murein lipoprotein (Lpp) is involved in inflammatory responses and septic shock. We previously characterized a lpp mutant of Yersinia pestis CO92 and found that this mutant was defective in surviving in macrophages and was attenuated in a mouse inhalation model of plague when compared to the highly virulent wild-type (WT) bacterium. We performed global transcriptional profiling of WT Y. pestis and its lpp mutant using microarrays. The organisms were cultured at 26 and 37 degrees Celsius to simulate the flea vector and mammalian host environments, respectively. Our data revealed vastly different effects of lpp mutation on the transcriptomes of Y. pestis grown at 37 versus . While the absence of Lpp resulted mainly in the downregulation of metabolic genes at , the Y. pestislpp mutant cultured at exhibited profound alterations in stress response and virulence genes, compared to WT bacteria. We investigated one of the stress-related genes (htrA) downregulated in the lpp mutant relative to WT Y. pestis. Indeed, complementation of the lpp mutant with the htrA gene restored intracellular survival of the Y. pestislpp mutant. Our results support a role for Lpp in Y. pestis adaptation to the host environment, possibly via transcriptional activation of htrA.
  • Thumbnail Image
    Crossing complexity of space-filling curves reveals entanglement of S-phase DNA
    Kinney, Nick; Hickman, Molly; Anandakrishnan, Ramu; Garner, Harold R. (2020-08-31)
    Space-filling curves have been used for decades to study the folding principles of globular proteins, compact polymers, and chromatin. Formally, space-filling curves trace a single circuit through a set of points (x,y,z); informally, they correspond to a polymer melt. Although not quite a melt, the folding principles of Human chromatin are likened to the Hilbert curve: a type of space-filling curve. Hilbert-like curves in general make biologically compelling models of chromatin; in particular, they lack knots which facilitates chromatin folding, unfolding, and easy access to genes. Knot complexity has been intensely studied with the aid of Alexander polynomials; however, the approach does not generalize well to cases of more than one chromosome. Crossing complexity is an understudied alternative better suited for quantifying entanglement between chromosomes. Do Hilbert-like configurations limit crossing complexity between chromosomes? How does crossing complexity for Hilbert-like configurations compare to equilibrium configurations? To address these questions, we extend the Mansfield algorithm to enable sampling of Hilbert-like space filling curves on a simple cubic lattice. We use the extended algorithm to generate equilibrium, intermediate, and Hilbert-like configurational ensembles and compute crossing complexity between curves (chromosomes) in each configurational snapshot. Our main results are twofold: (a) Hilbert-like configurations limit entanglement between chromosomes and (b) Hilbert-like configurations do not limit entanglement in a model of S-phase DNA. Our second result is particularly surprising yet easily rationalized with a geometric argument. We explore ergodicity of the extended algorithm and discuss our results in the context of more sophisticated models of chromatin.
  • Thumbnail Image
    'Cut from the same cloth': Shared microsatellite variants among cancers link to ectodermal tissues-neural tube and crest cells
    Karunasena, Enusha; McIver, Lauren J.; Bavarva, Jasmin H.; Wu, Xiaowei; Zhu, Hongxiao; Garner, Harold R. (Impact Journals, 2015-09-08)
  • Thumbnail Image
    Deja vu: a database of highly similar citations in the scientific literature
    Errami, Mounir; Sun, Zhaohui; Long, Tara C.; George, Angela C.; Garner, Harold R. (Oxford University Press, 2008-08-09)
    In the scientific research community, plagiarism and covert multiple publications of the same data are considered unacceptable because they undermine the public confidence in the scientific integrity. Yet, little has been done to help authors and editors to identify highly similar citations, which sometimes may represent cases of unethical duplication. For this reason, we have made available De´ ja` vu, a publicly available database of highly similar Medline citations identified by the text similarity search engine eTBLAST. Following manual verification, highly similar citation pairs are classified into various categories ranging from duplicates with different authors to sanctioned duplicates. De´ ja` vu records also contain user-provided commentary and supporting information to substantiate each document’s categorization. De´ ja` vu and eTBLAST are available to authors, editors, reviewers, ethicists and sociologists to study, intercept, annotate and deter questionable publication practices. These tools are part of a sustained effort to enhance the quality of Medline as ‘the’ biomedical corpus. The De´ ja` vu database is freely accessible at http://spore.swmed.edu/dejavu. The tool eTBLAST is also freely available at http://etblast.org.
  • Thumbnail Image
    Differentiating between cancer and normal tissue samples using multi-hit combinations of genetic mutations
    Dash, Sajal; Kinney, N.A.; Varghese, Ronnie; Garner, Harold R.; Feng, Wu-chun; Anandakrishnan, Ramu (Nature Publishing Group, 2019-01-30)
    Cancer is known to result from a combination of a small number of genetic defects. However, the specific combinations of mutations responsible for the vast majority of cancers have not been identified. Current computational approaches focus on identifying driver genes and mutations. Although individually these mutations can increase the risk of cancer they do not result in cancer without additional mutations. We present a fundamentally different approach for identifying the cause of individual instances of cancer: we search for combinations of genes with carcinogenic mutations (multi-hit combinations) instead of individual driver genes or mutations. We developed an algorithm that identified a set of multi-hit combinations that differentiate between tumor and normal tissue samples with 91% sensitivity (95% Confidence Interval (CI) = 89–92%) and 93% specificity (95% CI = 91–94%) on average for seventeen cancer types. We then present an approach based on mutational profile that can be used to distinguish between driver and passenger mutations within these genes. These combinations, with experimental validation, can aid in better diagnosis, provide insights into the etiology of cancer, and provide a rational basis for designing targeted combination therapies. © 2019, The Author(s).
  • Thumbnail Image
    Dynamic innate immune responses of human bronchial epithelial cells to severe acute respiratory syndrome-associated coronavirus infection
    Yoshikawa, Tomoki; Hill, Terence E.; Yoshikawa, Naoko; Popov, Vsevolod L.; Galindo, Cristi L.; Garner, Harold R.; Peters, C. J.; Tseng, Chien-Te (Kent) (Public Library of Science, 2010-01-15)
    Human lung epithelial cells are likely among the first targets to encounter invading severe acute respiratory syndromeassociated coronavirus (SARS-CoV). Not only can these cells support the growth of SARS-CoV infection, but they are also capable of secreting inflammatory cytokines to initiate and, eventually, aggravate host innate inflammatory responses, causing detrimental immune-mediated pathology within the lungs. Thus, a comprehensive evaluation of the complex epithelial signaling to SARS-CoV is crucial for paving the way to better understand SARS pathogenesis. Based on microarraybased functional genomics, we report here the global gene response of 2B4 cells, a cloned bronchial epithelial cell line derived from Calu-3 cells. Specifically, we found a temporal and spatial activation of nuclear factor (NF)kB, activator protein (AP)-1, and interferon regulatory factor (IRF)-3/7 in infected 2B4 cells at 12-, 24-, and 48-hrs post infection (p.i.), resulting in the activation of many antiviral genes, including interferon (IFN)-b, -ls, inflammatory mediators, and many IFN-stimulated genes (ISGs). We also showed, for the first time, that IFN-b and IFN-ls were capable of exerting previously unrecognized, non-redundant, and complementary abilities to limit SARS-CoV replication, even though their expression could not be detected in infected 2B4 bronchial epithelial cells until 48 hrs p.i. Collectively, our results highlight the mechanics of the sequential events of antiviral signaling pathway/s triggered by SARS-CoV in bronchial epithelial cells and identify novel cellular targets for future studies, aiming at advancing strategies against SARS.
  • Thumbnail Image
    EvoCor: a platform for predicting functionally related genes using phylogenetic and expression profiles
    Dittmar, W. James; McIver, Lauren; Michalak, Pawel; Garner, Harold R.; Valdez, Gregorio (2014-07-01)
    The wealth of publicly available gene expression and genomic data provides unique opportunities for computational inference to discover groups of genes that function to control specific cellular processes. Such genes are likely to have co-evolved and be expressed in the same tissues and cells. Unfortunately, the expertise and computational resources required to compare tens of genomes and gene expression data sets make this type of analysis difficult for the average end-user. Here, we describe the implementation of a web server that predicts genes involved in affecting specific cellular processes together with a gene of interest. We termed the server 'EvoCor', to denote that it detects functional relationships among genes through evolutionary analysis and gene expression correlation. This web server integrates profiles of sequence divergence derived by a Hidden Markov Model (HMM) and tissue-wide gene expression patterns to determine putative functional linkages between pairs of genes.
  • Thumbnail Image
    Exome-Wide Somatic Microsatellite Variation Is Altered in Cells with DNA Repair Deficiencies
    Vaksman, Zalman; Fonville, Natalie C.; Tae, Hongseok; Garner, Harold R. (PLOS, 2014-11-17)
    Microsatellites (MST), tandem repeats of 1–6 nucleotide motifs, are mutational hot-spots with a bias for insertions and deletions (INDELs) rather than single nucleotide polymorphisms (SNPs). The majority of MST instability studies are limited to a small number of loci, the Bethesda markers, which are only informative for a subset of colorectal cancers. In this paper we evaluate non-haplotype alleles present within next-gen sequencing data to evaluate somatic MST variation (SMV) within DNA repair proficient and DNA repair defective cell lines. We confirm that alleles present within next-gen data that do not contribute to the haplotype can be reliably quantified and utilized to evaluate the SMV without requiring comparisons of matched samples. We observed that SMV patterns found in DNA repair proficient cell lines without DNA repair defects, MCF10A, HEK293 and PD20 RV:D2, had consistent patterns among samples. Further, we were able to confirm that changes in SMV patterns in cell lines lacking functional BRCA2, FANCD2 and mismatch repair were consistent with the different pathways perturbed. Using this new exome sequencing analysis approach we show that DNA instability can be identified in a sample and that patterns of instability vary depending on the impaired DNA repair mechanism, and that genes harboring minor alleles are strongly associated with cancer pathways. The MST Minor Allele Caller used for this study is available at https://github.com/zalmanv/MST_minor_allele_caller.
  • Thumbnail Image
    Genomic divergence and adaptive convergence in Drosophila simulans from Evolution Canyon, Israel
    Kang, Lin; Rashkovetsky, Eugenia; Michalak, Katarzyna; Garner, Harold R.; Mahaney, James E.; Rzigalinski, Beverly A.; Korol, Abraham B.; Nevo, Eviatar; Michalak, Pawel (2019-06-11)
    Biodiversity refugia formed by unique features of the Mediterranean arid landscape, such as the dramatic ecological contrast of "Evolution Canyon," provide a natural laboratory in which local adaptations to divergent microclimate conditions can be investigated. Significant insights have been provided by studies of Drosophila melanogaster diversifying along the thermal gradient in Evolution Canyon, but a comparative framework to survey adaptive convergence across sister species at the site has been lacking. To fill this void, we present an analysis of genomic polymorphism and evolutionary divergence of Drosophila simulans, a close relative of Drosophila melanogaster with which it co-occurs on both slopes of the canyon. Our results show even deeper interslope divergence in D. simulans than in D. melanogaster, with extensive signatures of selective sweeps present in flies from both slopes but enhanced in the population from the hotter and drier south-facing slope. Interslope divergence was enriched for genes related to electrochemical balance and transmembrane transport, likely in response to increased selection for dehydration resistance on the hotter slope. Both species shared genomic regions that underwent major selective sweeps, but the overall level of adaptive convergence was low, demonstrating no shortage of alternative genomic solutions to cope with the challenges of the microclimate contrast. Mobile elements were a major source of genetic polymorphism and divergence, affecting all parts of the genome, including coding sequences of mating behavior-related genes.
  • Thumbnail Image
    Identifying multi-hit carcinogenic gene combinations: Scaling up a weighted set cover algorithm using compressed binary matrix representation on a GPU
    Al Hajri, Qais; Dash, Sajal; Feng, Wu-chun; Garner, Harold R.; Anandakrishnan, Ramu (Nature Publishing Group, 2020-02-06)
    Despite decades of research, effective treatments for most cancers remain elusive. One reason is that different instances of cancer result from different combinations of multiple genetic mutations (hits). Therefore, treatments that may be effective in some cases are not effective in others. We previously developed an algorithm for identifying combinations of carcinogenic genes with mutations (multi-hit combinations), which could suggest a likely cause for individual instances of cancer. Most cancers are estimated to require three or more hits. However, the computational complexity of the algorithm scales exponentially with the number of hits, making it impractical for identifying combinations of more than two hits. To identify combinations of greater than two hits, we used a compressed binary matrix representation, and optimized the algorithm for parallel execution on an NVIDIA V100 graphics processing unit (GPU). With these enhancements, the optimized GPU implementation was on average an estimated 12,144 times faster than the original integer matrix based CPU implementation, for the 3-hit algorithm, allowing us to identify 3-hit combinations. The 3-hit combinations identified using a training set were able to differentiate between tumor and normal samples in a separate test set with 90% overall sensitivity and 93% overall specificity. We illustrate how the distribution of mutations in tumor and normal samples in the multi-hit gene combinations can suggest potential driver mutations for further investigation. With experimental validation, these combinations may provide insight into the etiology of cancer and a rational basis for targeted combination therapy.
  • Thumbnail Image
    Inhibitory Role of Notch1 in Calcific Aortic Valve Disease
    Acharya, Asha; Hans, Chetan P.; Koenig, Sara N.; Nichols, Haley A.; Galindo, Cristi L.; Garner, Harold R.; Merrill, Walter H.; Hinton, Robert B.; Garg, Vidu (PLoS ONE, 2011-11-16)
    Aortic valve calcification is the most common form of valvular heart disease, but the mechanisms of calcific aortic valve disease (CAVD) are unknown. NOTCH1 mutations are associated with aortic valve malformations and adult-onset calcification in families with inherited disease. The Notch signaling pathway is critical for multiple cell differentiation processes, but its role in the development of CAVD is not well understood. The aim of this study was to investigate the molecular changes that occur with inhibition of Notch signaling in the aortic valve. Notch signaling pathway members are expressed in adult aortic valve cusps, and examination of diseased human aortic valves revealed decreased expression of NOTCH1 in areas of calcium deposition. To identify downstream mediators of Notch1, we examined gene expression changes that occur with chemical inhibition of Notch signaling in rat aortic valve interstitial cells (AVICs). We found significant downregulation of Sox9 along with several cartilage-specific genes that were direct targets of the transcription factor, Sox9. Loss of Sox9 expression has been published to be associated with aortic valve calcification. Utilizing an in vitro porcine aortic valve calcification model system, inhibition of Notch activity resulted in accelerated calcification while stimulation of Notch signaling attenuated the calcific process. Finally, the addition of Sox9 was able to prevent the calcification of porcine AVICs that occurs with Notch inhibition. In conclusion, loss of Notch signaling contributes to aortic valve calcification via a Sox9-dependent mechanism.
  • Thumbnail Image
    The Kub5-Hera/RPRD1B interactome: a novel role in preserving genetic stability by regulating DNA mismatch repair
    Patidar, Praveen L.; Motea, Edward A.; Fattah, Farjana J.; Zhou, Yunyun; Morales, Julio C.; Xie, Yang; Garner, Harold R.; Boothman, David A. (2016-02-29)
    Ku70-binding protein 5 (Kub5)-Hera (K-H)/RPRD1B maintains genetic integrity by concomitantly minimizing persistent R-loops and promoting repair of DNA double strand breaks (DSBs). We used tandem affinity purification-mass spectrometry, coimmunoprecipitation and gel-filtration chromatography to define higher-order protein complexes containing K-H scaffolding protein to gain insight into its cellular functions. We confirmed known protein partners (Ku70, RNA Pol II, p15RS) and discovered several novel associated proteins that function in RNA metabolism (Topoisomerase 1 and RNA helicases), DNA repair/replication processes (PARP1, MSH2, Ku, DNA-PKcs, MCM proteins, PCNA and DNA Pol delta) and in protein metabolic processes, including translation. Notably, this approach directed us to investigate an unpredicted involvement of K-H in DNA mismatch repair (MMR) where K-H depletion led to concomitant MMR deficiency and compromised global microsatellite stability. Mechanistically, MMR deficiency in K-H-depleted cells was a consequence of reduced stability of the core MMR proteins (MLH1 and PMS2) caused by elevated basal caspase-dependent proteolysis. Pan-caspase inhibitor treatment restored MMR protein loss. These findings represent a novel mechanism to acquire MMR deficiency/microsatellite alterations. A significant proportion of colon, endometrial and ovarian cancers exhibit k-h expression/copy number loss and may have severe mutator phenotypes with enhanced malignancies that are currently overlooked based on sporadic MSI+ screening.
  • Thumbnail Image
    Role of SPI-1 Secreted Effectors in Acute Bovine Response to Salmonella enterica Serovar Typhimurium: A Systems Biology Analysis Approach
    Lawhon, Sara D.; Khare, Sangeeta; Rossetti, Carlos A.; Everts, Robin E.; Galindo, Cristi L.; Luciano, Sarah A.; Figueiredo, Josely F.; Nunes, Jairo E. S.; Gull, Tamara; Davidson, George S.; Drake, Kenneth L.; Garner, Harold R.; Lewin, Harris A.; Baumler, Andreas J.; Adams, Leslie Garry (Public Library of Science, 2011-11-11)
    Salmonella enterica Serovar Typhimurium (S. Typhimurium) causes enterocolitis with diarrhea and polymorphonuclear cell (PMN) influx into the intestinal mucosa in humans and calves. The Salmonella Type III Secretion System (T3SS) encoded at Pathogenicity Island I translocates Salmonella effector proteins SipA, SopA, SopB, SopD, and SopE2 into epithelial cells and is required for induction of diarrhea. These effector proteins act together to induce intestinal fluid secretion and transcription of C-X-C chemokines, recruiting PMNs to the infection site. While individual molecular interactions of the effectors with cultured host cells have been characterized, their combined role in intestinal fluid secretion and inflammation is less understood. We hypothesized that comparison of the bovine intestinal mucosal response to wild type Salmonella and a SipA, SopABDE2 effector mutant relative to uninfected bovine ileum would reveal heretofore unidentified diarrhea-associated host cellular pathways. To determine the coordinated effects of these virulence factors, a bovine ligated ileal loop model was used to measure responses to wild type S. Typhimurium (WT) and a ΔsipA, sopABDE2 mutant (MUT) across 12 hours of infection using a bovine microarray. Data were analyzed using standard microarray analysis and a dynamic Bayesian network modeling approach (DBN). Both analytical methods confirmed increased expression of immune response genes to Salmonella infection and novel gene expression. Gene expression changes mapped to 219 molecular interaction pathways and 1620 gene ontology groups. Bayesian network modeling identified effects of infection on several interrelated signaling pathways including MAPK, Phosphatidylinositol, mTOR, Calcium, Toll-like Receptor, CCR3, Wnt, TGF-β, and Regulation of Actin Cytoskeleton and Apoptosis that were used to model of host-pathogen interactions. Comparison of WT and MUT demonstrated significantly different patterns of host response at early time points of infection (15 minutes, 30 minutes and one hour) within phosphatidylinositol, CCR3, Wnt, and TGF-β signaling pathways and the regulation of actin cytoskeleton pathway.
  • Thumbnail Image
    Scaling out a combinatorial algorithm for discovering carcinogenic gene combinations to thousands of GPUs
    Dash, Sajal; Al-Hajri, Qais; Feng, Wu-chun; Garner, Harold R.; Anandakrishnan, Ramu (IEEE, 2021-05-01)
    Cancer is a leading cause of death in the US, second only to heart disease. It is primarily a result of a combination of an estimated two-nine genetic mutations (multi-hit combinations). Although a body of research has identified hundreds of cancer-causing genetic mutations, we don't know the specific combination of mutations responsible for specific instances of cancer for most cancer types. An approximate algorithm for solving the weighted set cover problem was previously adapted to identify combinations of genes with mutations that may be responsible for individual instances of cancer. However, the algorithm's computational requirement scales exponentially with the number of genes, making it impractical for identifying more than three-hit combinations, even after the algorithm was parallelized and scaled up to a V100 GPU. Since most cancers have been estimated to require more than three hits, we scaled out the algorithm to identify combinations of four or more hits using 1000 nodes (6000 V100 GPUs with ≈ 48× 106 processing cores) on the Summit supercomputer at Oak Ridge National Laboratory. Efficiently scaling out the algorithm required a series of algorithmic innovations and optimizations for balancing an exponentially divergent workload across processors and for minimizing memory latency and inter-node communication. We achieved an average strong scaling efficiency of 90.14% (80.96%-97.96% for 200 to 1000 nodes), compared to a 100 node run, with 84.18% scaling efficiency for 1000 nodes. With experimental validation, the multi-hit combinations identified here could provide further insight into the etiology of different cancer subtypes and provide a rational basis for targeted combination therapy.
  • Thumbnail Image
    Selective amplification of Brucella melitensis mRNA from a mixed host:pathogen total RNA
    Rossetti, Carlos A.; Galindo, Cristi L.; Garner, Harold R.; Adams, L. Garry (2010-09-28)
    Background Brucellosis is a worldwide anthropozoonotic disease caused by an in vivo intracellular pathogen belonging to genus Brucella. The characterization of brucelae transcriptome's during host-pathogen interaction has been limited due to the difficulty of obtaining an adequate quantity of good quality eukaryotic RNA-free pathogen RNA for downstream applications. Findings Here, we describe a combined protocol to prepare RNA from intracellular B. melitensis in a quantity and quality suitable for pathogen gene expression analysis. Initially, B. melitensis total RNA was enriched from a host:pathogen mixed RNA sample by reducing the eukaryotic RNA..Then, to increase the Brucella RNA concentration and simultaneously minimize the contaminated host RNA in the mixed sample, a specific primer set designed to anneal to all B. melitensis ORF allows the selective linear amplification of sense-strand prokaryotic transcripts in a previously enriched RNA sample. Conclusion The novelty of the method we present here allows analysis of the gene expression profile of B. melitensis when limited amounts of pathogen RNA are present, and is potentially applicable to both in vivo and in vitro models of infection, even at early infection time points.