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Modeling gene expression networks using fuzzy logic.

Gene regulatory networks model regulation in living organisms. Fuzzy logic can effectively model gene regulation and interaction to accurately reflect the underlying biology. A new multiscale fuzzy clustering method allows genes to interact between regulatory pathways and across different conditions at different levels of detail. Fuzzy cluster centers can be used to quickly discover causal relationships between groups of coregulated genes. Fuzzy measures weight expert knowledge and help quantify uncertainty about the functions of genes using annotations and the gene ontology database to confirm some of the interactions. The method is illustrated using gene expression data from an experiment on carbohydrate metabolism in the model plant Arabidopsis thaliana. Key gene regulatory relationships were evaluated using information from the gene ontology database. A new regulatory relationship concerning trehalose regulation of carbohydrate metabolism was also discovered in the extracted network.

Animals↗

NR3C1 Modulates Wnt Signalling to Influence the Invasiveness and Immune Features of Nonfunctioning Invasive Pituitary Adenomas.

Pituitary adenomas (PAs) are common intracranial tumours, and invasiveness in nonfunctioning invasive pituitary adenomas (NIPAs) predicts poor prognosis. The molecular mechanisms driving this phenotype remain unclear. This study explored the role of nuclear receptor subfamily 3 group C member 1 (NR3C1) in NIPA invasiveness and its regulation of Wnt signalling. mRNA expression profiles of 32 PA samples were generated by RNA-seq, and proteomic data from 19 samples were obtained by mass spectrometry. Immune-related differentially expressed genes (DEGs) were retrieved from GeneCards. Weighted gene coexpression network analysis identified modules and hub genes linked to invasiveness, while machine learning methods (support vector machine, LASSO, random forest) prioritised key genes. Gene set enrichment analysis (GSEA) assessed pathways associated with candidate gene expression. NR3C1 expression and function were validated by immunohistochemistry, Western blotting and invasion assays. Integration of transcriptomic, proteomic and immune-related datasets yielded 11 overlapping genes, with NR3C1 emerging as the top candidate. NR3C1 was significantly upregulated in NIPAs and demonstrated good discriminatory power by ROC analysis. GSEA associated high NR3C1 expression with Wnt pathway activation. Functional experiments confirmed that NR3C1 overexpression enhances the invasive capacity of PA cells. NR3C1 promotes the invasive phenotype of NIPAs by activating Wnt signalling. These findings suggest NR3C1 as a potential biomarker and therapeutic target for invasive pituitary adenomas.

Humans↗

MAdLandExpression: integrating sexual reproduction into the Physcomitrium patens expression atlas.

Physcomitrium patens is a bryophyte model system particularly valuable for evolutionary developmental and comparative genomics studies. Sexual reproduction in bryophytes offers unique insights into the evolution of land plant reproduction. Unlike seed plants, bryophytes have a dominant gametophyte phase and provide significant advantages for studying sexual reproduction, such as the possibility to maintain embryo-lethal mutants through vegetative propagation or the presence of motile male gametes. More than 25 years after the first publications of transcriptomic data for P. patens, expression data of most developmental stages of P. patens as well as its responses to various biotic and abiotic perturbations have been represented by microarrays or RNA-seq datasets. To facilitate the use of such data, we introduce the MAdLandExpression atlas as a successor of PEATmoss (Physcomitrium Expression Atlas Tool), integrating its 109 P. patens expression experiments and expanding it with 20 recently published RNA-seq samples of sexual reproduction stages, thus completing the coverage of the P. patens life cycle. The MAdLandExpression atlas also introduces new features for data visualization and analysis, such as the comparison of samples from multiple datasets and gene set normalization. Using this tool, the sexual reproduction dataset was analyzed, identifying genes potentially important for egg and sperm cell development, and confirming the behavior of known key genes in sexual development observed in previous studies.

Bryopsida↗

Tumor suppressor in lung cancer 1 (TSLC1) alters tumorigenic growth properties and gene expression.

BACKGROUND: Introduction of cDNA or genomic clones of the tumor suppressor in lung cancer 1 (TSLC1) gene into the non-small cell lung cancer line, A549, reverses tumorigenic growth properties of these cells. These results and the observation that TSLC1 is down-regulated in a number of tumors suggest that TSLC1 functions as a critical switch mediating repression of tumorigenesis. RESULTS: To investigate this mechanism, we compared growth properties of A549 with the TSLC1-containing derivative. We found a G1/S phase transition delay in 12.2. Subtractive hybridization, quantitative PCR, and TranSignal Protein/DNA arrays were used to identify genes whose expression changed when TSLC1 was up-regulated. Members of common G1/S phase regulatory pathways such as TP53, MYC, RB1 and HRAS were not differentially expressed, indicating that TSLC1 may function through an alternative pathway(s). A number of genes involved in cell proliferation and tumorigenesis were differentially expressed, notably genes in the Ras-induced senescence pathway. We examined expression of several of these key genes in human tumors and normal lung tissue, and found similar changes in expression, validating the physiological relevance of the A549 and 12.2 cell lines. CONCLUSION: Gene expression and cell cycle differences provide insights into potential downstream pathways of TSLC1 that mediate the suppression of tumor properties in A549 cells.

Carcinoma, Non-Small-Cell Lung↗

[Modeling dynamics of gene net, regulating the cell cycle in mammalian cells].

The study of the molecular mechanisms determining cellular programs of proliferation, differentiation, and apoptosis is currently attracting much attention. Recent studies have demonstrated that the system of cell-cycle control based on the transcriptional regulation of the expression of specific genes is responsible for the transition between programs. These groups of functionally connected genes from so-called gene networks characterized by numerous feedbacks and a complex behavioral dynamics. Computer simulation methods have been applied to studying the dynamics of gene networks regulating the cell cycle of vertebrates. The data on the regulation of the key genes obtained from the CYCLE-TRRD database have been used as a basis to construct gene networks of different degrees of complexity controlling the G1/S transition, one of the most important stages of the cell cycle. The behavior dynamics of the model constructed has been analyzed. Two qualitatively different functional modes of the system has been obtained. It has also been shown that the transition between these modes depends on the duration of the proliferation signal. It has also been demonstrated that the additional feedback from factor E2F to genes c-fos and c-jun, which was predicted earlier based on the computer analysis of promoters, plays an important role in the transition of the cell to the S phase.

Animals↗

[SOS-induction in the presence of the plasmid pKM101 in the bacterial cells Escherichia coli K12].

Induction of transcription by the plasmid pKM101 (mutability mediating derivate of the plasmid R46) of the sfiA gene controlling cell division and of the fruA gene encoding the fructose specific enzyme II of the phosphoenolpyruvate-phosphotransferase system in intact cultures of Escherichia coli was studied. The genes under study were fused to the bacteriophage Mu dl (Ap lac). Activation of the sfiA gene, a typical member of the SOS-regulon, was demonstrated to depend on the key genes of the SOS-system-recA and lexA. In contrast, the fruA gene that is non-inducible by the UV-light, a classical SOS-inducing agent, is not activated by the presence of the plasmid pKMIO1 in the bacterial cells. The data obtained suggest that the presence of pKMIO1 plasmid in the Escherichia coli cells induces a SOS-signal as a consequence of the plasmid DNA replication or its conjugative transfer.

Bacterial Proteins↗

Long-day photoperiod promotes growth of pea (Pisum sativum L.) via auxin biosynthesis and polar transport.

Photoperiodic sensitivity is an essential factor that may affect agricultural practices under current climate scenarios. This study used pea (Pisum sativum) to examine effects of varying photoperiods on growth and photosynthetic parameters and then reveal the mechanistic basis of this process by linking them with tissue-specific distribution of auxin and regulation of related genes. This was achieved by transcriptome sequencing, genome-wide gene family identification, and expression pattern analysis. Best results in terms of growth and yield were obtained with a 20 h/4 h light/dark photoperiod and these plants had the highest content of endogenous indole-3-acetic acid (IAA) in both the shoot apex and the root. Genes consistently upregulated with prolonged light exposure were significantly enriched in pathways related to light signal transduction, photosynthetic carbon metabolism, and phytohormone signal transduction. Through genome-wide identification, we characterized the TAA/TAR and YUCCA families (key gene families involved in auxin biosynthesis) as well as the PIN family (responsible for auxin polar transport) in pea. Extending the light duration positively affected expression of several genes related to auxin biosynthesis and transport, among them members of the Elongated Hypocotyl (HY) and Phytochrome-Interacting Factor (PIF) families being key light-induced transcription factors, PsTAR2, the principal gene regulating auxin biosynthesis, as well as PsPIN4, PsPIN5, PsPIN11, and PsPIN13 which mediate polar auxin transport. By elucidating mechanisms underlying the coordinated regulation of pea growth by light and auxin, this work provides a significant reference for photoperiod research on long-day crops for both protected- and field-based horticulture.

Auxin↗

Omics approaches to unravel insecticide resistance mechanism in Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae).

Bemisia tabaci (Gennadius) whitefly (BtWf) is an invasive pest that has already spread worldwide and caused major crop losses. Numerous strategies have been implemented to control their infestation, including the use of insecticides. However, prolonged insecticide exposures have evolved BtWf to resist these chemicals. Such resistance mechanism is known to be regulated at the molecular level and systems biology omics approaches could shed some light on understanding this regulation wholistically. In this review, we discuss the use of various omics techniques (genomics, transcriptomics, proteomics, and metabolomics) to unravel the mechanism of insecticide resistance in BtWf. We summarize key genes, enzymes, and metabolic regulation that are associated with the resistance mechanism and review their impact on BtWf resistance. Evidently, key enzymes involved in the detoxification system such as cytochrome P450 (CYP), glutathione S-transferases (GST), carboxylesterases (COE), UDP-glucuronosyltransferases (UGT), and ATP binding cassette transporters (ABC) family played key roles in the resistance. These genes/proteins can then serve as the foundation for other targeted techniques, such as gene silencing techniques using RNA interference and CRISPR. In the future, such techniques will be useful to knock down detoxifying genes and crucial neutralizing enzymes involved in the resistance mechanism, which could lead to solutions for coping against BtWf infestation.

Hemiptera↗

Discovering causes and cures for cancer from gene expression analysis.

Tumorigenesis is governed by a series of complex genetic and epigenetic changes. Both mechanisms can result in either the silencing or aberrant expression of messages in a cell. Gene expression profiling techniques such as the serial analysis of gene expression (SAGE) or microarray analysis can provide global overviews of these changes, as well identify key genes and pathways involved in this process. This review outlines the current roles of these techniques in cancer research, and how they may contribute to finding not only mechanisms of this disease, but potential targets for therapy.

Biomarkers, Tumor↗

A novel t(3;8)(q27;q24.1) simultaneously involving both the BCL6 and MYC genes in a diffuse large B-cell lymphoma.

Diffuse large B-cell lymphomas (DLBCLs) are a clinically and biologically heterogeneous group of hematologic malignancies. Specific genetic aberrations underlie some of this heterogeneity. These genetic events include distinct and separate translocations resulting in the dysregulated expression of either BCL6 protein with the t(3;14)(q27;q32) or c-MYC protein with the t(8;14)(q24;q32), as a consequence of the juxtaposition of these oncogenes with heterologous promoters or enhancers, such as those of the immunoglobulin heavy chain gene. Here, we report the case of a patient with DLBCL with a unique t(3;8)(q27;q24.1) that involves the BCL6 and MYC genes. We know of no previous report of this translocation in DLBCL, which simultaneously affects two key genes implicated in lymphomagenesis and may reflect a novel genetic mechanism in neoplastic transformation.

Chromosomes, Human, Pair 14↗

The L27 domain of MPP7 enhances TAZ-YY1 cooperation to renew muscle stem cells.

Stem cells regenerate differentiated cells to maintain and repair tissues and organs. They also replenish themselves, i.e. self-renew, to support a lifetime of regenerative capacity. Here we study the renewal of skeletal muscle stem cell (MuSC) during regeneration. The transcriptional co-factors TAZ/YAP (via the TEAD transcription factors) regulate cell cycle and growth while the transcription factor YY1 regulates metabolic programs for MuSC activation. We show that MPP7 and AMOT join TAZ and YY1 to regulate a selected number of common genes that harbor TEAD and YY1 binding sites. Among these common genes, Carm1 can direct MuSC renewal. We demonstrate that the L27 domain of MPP7 enhances the interaction as well as the transcriptional activity of TAZ and YY1, while AMOT acts as an intermediate to bridge them together. Furthermore, MPP7, TAZ and YY1 co-occupy the promoters of Carm1 and other common downstream genes. Our results define a renewal program comprised of two progenitor transcriptional programs, in which selected key genes are regulated by protein-protein interactions, dependent on promoter context.

YY1 Transcription Factor↗

Minor form of trigonocephaly is an autistic skull shape? A suggestion based on homeobox gene variants and MECP2 mutations.

A possible role for Hoxa1 genotype in susceptibility to autism spectrum disorders was recently proposed. Furthermore, it has been demonstrated that Rett syndrome, which is categorized into pervasive developmental disorders the same as the autism spectrum disorders are, is associated with mutations in MECP2 gene. These findings suggest that the genetic backgrounds of these behavioral conditions may involve genes which also have an important role in the development of skull, because Hoxa1 is a key gene for skull development as well as for brain development and one of the clinical characteristics of Rett syndrome is deceleration in head growth. Together with this evolving knowledge, a series of ethical arguments concerning the indication of surgical treatment in patients with minor forms of trigonocephaly with autistic behaviors and/or hyperactivity leads us to hypothesize the presence of an autism subtype which may frequently be accompanied by specific morphological skull characteristics (autistic skull shape).

Attention Deficit Disorder with Hyperactivity↗

Cell cycle-regulated gene expression in Arabidopsis.

Regulated gene expression is an important mechanism for controlling cell cycle progression in yeast and mammals, and genes involved in cell division-related processes often show transcriptional regulation dependent on cell cycle position. Analysis of cell cycle processes in plants has been hampered by the lack of synchronizable cell suspensions for Arabidopsis, and few cell cycle-regulated genes are known. Using a recently described synchrony system, we have analyzed RNA from sequential samples of Arabidopsis cells progressing through the cell cycle using Affymetrix Genearrays. We identify nearly 500 genes that robustly display significant fluctuation in expression, representing the first genomic analysis of cell cycle-regulated gene expression in any plant. In addition to the limited number of genes previously identified as cell cycle-regulated in plants, we also find specific patterns of regulation for genes known or suspected to be involved in signal transduction, transcriptional regulation, and hormonal regulation, including key genes of cytokinin response. Genes identified represent pathways that are cell cycle-regulated in other organisms and those involved in plant-specific processes. The range and number of cell cycle-regulated genes show the close integration of the plant cell cycle into a variety of cellular control and response pathways.

Aphidicolin↗

Copper and iron are the limiting factors for growth of the yeast Saccharomyces cerevisiae in an alkaline environment.

Exposure of the yeast Saccharomyces cerevisiae to an alkaline environment represents a stress situation that negatively affects growth and results in an adaptive transcriptional response. We screened a collection of 4825 haploid deletion mutants for their ability to grow at mild alkaline pH, and we identified 118 genes, involved in numerous cellular functions, whose absence results in reduced growth. The list includes several key genes in copper and iron homeostasis, such as CCC2, RCS1, FET3, LYS7, and CTR1. In contrast, a screen of high-copy number plasmid libraries for clones able to increase tolerance to alkaline pH revealed only two genes: FET4 (encoding a low affinity transporter for copper, iron, and zinc) and CTR1 (encoding a high affinity copper transporter). The beneficial effect of overexpression of CTR1 requires a functional high affinity iron transport system, as it was abolished by deletion of FET3, a component of the high affinity transport system, or CCC2, which is required for assembly of the transport system. The growth-promoting effect of FET4 was not modified in these mutants. These results suggest that the observed tolerance to alkaline pH is because of improved iron uptake and indicate that both iron and copper are limiting factors for growth under alkaline pH conditions. Addition to the medium of micromolar concentrations of copper or iron ions drastically improved growth at high pH. Supplementation with iron improved somewhat the tolerance of a fet3 strain but was ineffective in a ctr1 mutant, suggesting the existence of additional copper-requiring functions important for tolerance to an alkaline environment.

Biological Transport↗

Barx1 and evolutionary changes in feeding.

During mouse embryonic development, the Barx1 homeobox gene is expressed in the mesenchymal cells of molar teeth and stomach. During early stages of molar development, Barx1 has an instructive role, directing the as yet undetermined ectomesenchymal cells in the proximal region of the jaws to follow a multicuspid tooth developmental pathway. We review here recent results showing an absence of stomach tissue in Barx1 mutant mice. The data strongly suggest that in the presumptive stomach mesenchyme Barx1 acts to attenuate Wnt signalling allowing digestive tract endoderm to differentiate into a highly specialized stomach epithelium. In the light of these new data, we discuss the possibility that evolutionary changes in the Barx1 gene could have simultaneously altered the dentition and the digestive system, therefore positioning Barx1 as a key gene in the evolution of mammals.

Animals↗

Obesity-related glomerulopathy: insights from gene expression profiles of the glomeruli derived from renal biopsy samples.

Obesity-related glomerulopathy (ORG) is an important complication of obesity. The pathophysiological mechanism of glomerular injury in ORG is incompletely understood. Gene expression profiles in the glomeruli obtained from renal biopsy samples of patients with ORG were investigated, using a microdissection technique combined with Affymetrix microarray analysis. Six patients presented with obesity, proteinuria, and biopsy-proven ORG were enrolled. Two sex- and age-matched donor kidneys were applied as the controls. Glomeruli were dissected out from renal biopsy samples under microscope, and total RNA was extracted using RNeasy Micro kit. After two rounds of T7 promoter-based RNA amplification, gene expression profiles of the glomeruli samples were detected using Affymetrix U133A gene chips. Bioinformatic tools were applied to analyze the microarray data. Results of candidate ORG-related genes were further confirmed by real-time quantitative PCR and immunohistochemistry staining using renal biopsy samples of a larger pool of 15 ORG patients. Genes related to lipid metabolism, inflammatory cytokines, and insulin resistance were the most highlighted subgroups that significantly changed in the glomerular gene expression profiles of the ORG patients, compared with the controls. The expression levels of several key genes in lipid metabolism were increased over 2-fold, including low-density lipoprotein receptor, fatty acid binding protein 3, and sterol regulatory element binding protein 1. Moreover, some inflammatory cytokines and their downstream molecules were increased as well, including TNF-alpha and its receptors, IL-6 signal transducer, and interferon-gamma. As the indicators of insulin resistance in the local glomerular cells, levels of glucose-transporter 1, leptin receptor, peroxisome proliferator-activated receptor-gamma, and vascular endothelial growth factor increased, too. In addition to lipid dysmetabolism and insulin resistance, the activation of an inflammatory process in the glomeruli might play a unique role in the development of obesity-related glomerulopathy. Our results expand the understanding of obesity-induced glomerular injuries and shed light on new approaches in the treatment of this disease.

Adult↗

Transcriptional profiling of mammary gland side population cells.

Similar to the bone marrow, the mammary gland contains a distinct population of Hoechst-effluxing side population cells, mammary gland side population cells (MG-SPs). To better characterize MG-SPs, their microarray gene profiles were compared to the remaining cells, which retain Hoechst dye (mammary gland non-side population cells [MG-NSPs]). For analysis, Gene Ontology (GO) that describes genes in terms of biological processes and Ontology Traverser (OT) that performs enrichment analysis were used. OT showed that MG-SP-specific genes were enriched in the GO categories of cell cycle regulation and checkpoints, multidrug-resistant transporters, organogenesis, and vasculogenesis. The MG-NSP-upregulated genes were enriched in the GO category of cellular organization and biogenesis, which includes basal epithelial markers, p63, smooth muscle actin, myosin, alpha6 integrin, cytokeratin (CK) 14, and luminal markers CK8 and CD24. Additional studies showed that a higher percentage of MG-SPs exist in the G1 phase of the cell cycle compared with the MG-NSPs. G1 cell cycle block of MG-SPs may be explained by higher expression of cell cycle-negative regulatory genes such as transforming growth factor-beta2, insulin-like growth factor binding protein-5, P18(INK4C), and wingless-5a (Wnt-5a). Accordingly, a smaller percentage of MG-SPs expressed nuclear beta-catenin, possibly as a consequence of the higher expression of Wnt-5a. In conclusion, microarray gene profiling suggests that MG-SPs are a lineage-deficient mammary gland subpopulation expressing key genes involved in cell cycle regulation, development, and angiogenesis.

Animals↗

Granulocytes govern the transcriptional response, morphology and proliferation of Candida albicans in human blood.

Survival in blood and escape from blood vessels into tissues are essential steps for the yeast Candida albicans to cause systemic infections. To elucidate the influence of blood components on fungal growth, morphology and transcript profile during bloodstream infections, we exposed C. albicans to blood, blood fractions enriched in erythrocytes, polymorphonuclear or mononuclear leukocytes, blood depleted of neutrophils and plasma. C. albicans cells exposed to erythrocytes, mononuclear cells, plasma or blood lacking neutrophils were physiologically active and rapidly switched to filamentous growth. In contrast, the presence of neutrophils arrested C. albicans growth, enhanced the fungal response to overcome nitrogen and carbohydrate starvation, and induced the expression of a large number of genes involved in the oxidative stress response. In particular, SOD5, encoding a glycosylphosphatidylinositol (GPI)-anchored superoxide dismutase localized on the cell surface of C. albicans, was strongly expressed in yeast cells that were associated with neutrophils. Mutants lacking key genes involved in oxidative stress, morphology or virulence had significantly reduced survival rates in blood and the neutrophil fraction, but remained viable for at least 1 h of incubation when exposed to erythrocytes, mononuclear cells, plasma or blood lacking neutrophils. These data suggest that C. albicans genes expressed in blood were predominantly induced in response to neutrophils, and that neutrophils play a key role during C. albicans bloodstream infections. However, C. albicans is equipped with several genes and transcriptional programmes, which may help the fungus to counteract the attack of neutrophils, to escape from the bloodstream and to cause systemic infections.

Blood↗