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Phenomic profiles are high-dimensional sets of readouts that can comprehensively capture the biological impact of chemical and genetic perturbations in cellular assay systems. Phenomic profiling of compound libraries can be used for compound target identification or mechanism of action (MoA) prediction and other applications in drug discovery. To devise an economical set of phenomic profiling assays, we assembled a library of 1,008 approved drugs and well-characterized tool compounds manually annotated to 218 unique MoAs, and we profiled each compound at four concentrations in live-cell, high-content imaging screens against a panel of 15 reporter cell lines, which expressed a diverse set of fluorescent organelle and pathway markers in three distinct cell lineages. For 41 of 83 testable MoAs, phenomic profiles accurately ranked the reference compounds (AUC-ROC ≥ 0.9). MoAs could be better resolved by screening compounds at multiple concentrations than by including replicates at a single concentration. Screening additional cell lineages and fluorescent markers increased the number of distinguishable MoAs but this effect quickly plateaued. There remains a substantial number of MoAs that were hard to distinguish from others under the current study’s conditions. We discuss ways to close this gap, which will inform the design of future phenomic profiling efforts.

Summary Reproducibility in molecular and cellular studies is fundamental to scientific discovery. To establish the reproducibility of a well-defined long-term neuronal differentiation protocol, we repeated the cellular and molecular comparison of the same two iPSC lines across five distinct laboratories. Despite uncovering acceptable variability within individual laboratories, we detect poor cross-site reproducibility of the differential gene expression signature between these two lines. Factor analysis identifies the laboratory as the largest source of variation along with several variation-inflating confounders such as passaging effects and progenitor storage. Single-cell transcriptomics shows substantial cellular heterogeneity underlying inter-laboratory variability and being responsible for biases in differential gene expression inference. Factor analysis-based normalization of the combined dataset can remove the nuisance technical effects, enabling the execution of robust hypothesis-generating studies. Our study shows that multi-center collaborations can expose systematic biases and identify critical factors to be standardized when publishing novel protocols, contributing to increased cross-site reproducibility., Highlights • Cross-site reproducibility in iPSC-based molecular experiments is poor • Factor analysis-based normalization can be used to analyze nuisance variation • External validation of iPSC experimental molecular data is critical for reproducibility • Collaborative studies are needed to reveal systematic biases to improve reproducibility, In this article, Lakics and colleagues show that, while individual laboratories are able to identify consistent molecular and seemingly statistically robust differences between iPSC neuronal models, cross-site reproducibility is poor. Their findings support multi-center collaborations to expose systematic biases and identify critical factors to be standardized to improve reproducibility in iPSC-based molecular experiments.

Summary Tauopathies such as frontotemporal dementia (FTD) remain incurable to date, partially due to the lack of translational in vitro disease models. The MAPT gene, encoding the microtubule-associated protein tau, has been shown to play an important role in FTD pathogenesis. Therefore, we used zinc finger nucleases to introduce two MAPT mutations into healthy donor induced pluripotent stem cells (iPSCs). The IVS10+16 mutation increases the expression of 4R tau, while the P301S mutation is pro-aggregant. Whole-transcriptome analysis of MAPT IVS10+16 neurons reveals neuronal subtype differences, reduced neural progenitor proliferation potential, and aberrant WNT/SHH signaling. Notably, these neurodevelopmental phenotypes could be recapitulated in neurons from patients carrying the MAPT IVS10+16 mutation. Moreover, the additional pro-aggregant P301S mutation revealed additional phenotypes, such as an increased calcium burst frequency, reduced lysosomal acidity, tau oligomerization, and neurodegeneration. This series of iPSCs could serve as a platform to unravel a potential link between pathogenic 4R tau and FTD., Highlights • Analysis of ZFN-engineered MAPT IVS10+16 with or without additional P301S mutation • Neurodevelopmental phenotypes in ZFN and patient-derived MAPT IVS10+16 neurons • Neurodegenerative phenotypes in MAPT IVS10+16/P301S double-mutant neurons, In this article, Verheyen and colleagues introduced 2 MAPT mutations (IVS10+16/P301S) into healthy donor iPSCs. Characterization of MAPT IVS10+16 neurons revealed neurodevelopmental neuron subtype differences, reduced neural progenitor proliferation, and aberrant WNT/SHH signaling, while the additional pro-aggregant P301S mutation revealed phenotypes more related to neurodegeneration. These iPSCs could help to unravel a potential link between pathogenic 4R tau and FTD.

For drug discovery, cell-based assays are becoming increasingly complex to mimic more realistically the nature of biological processes and their diversifications in diseases. Multicellular co-cultures embedded in a three-dimensional (3D) matrix have been explored in oncology to more closely approximate the physiology of the human tumor microenvironment. High-content analysis is the ideal technology to characterize these complex biological systems, although running such complex assays at higher throughput is a major endeavor. Here, we report on adapting a 3D tumor co-culture growth assay to automated microscopy, and we compare various imaging platforms (confocal vs. nonconfocal) with correlating automated image analysis solutions to identify optimal conditions and settings for future larger scaled screening campaigns. The optimized protocol has been validated in repeated runs where established anticancer drugs have been evaluated for performance in this innovative assay.

Background: Establishing preclinical models is essential for novel drug discovery in schizophrenia. Most existing models are characterized by abnormalities in behavioral readouts, which are informative, but do not necessarily translate to the symptoms of the human disease. Therefore, there is a necessity of characterizing the preclinical models from a molecular point of view. Selective reaction monitoring (SRM) has already shown promise in preclinical and clinical studies for multiplex measurement of diagnostic, prognostic and treatment-related biomarkers. Methods: We have established an SRM assay for multiplex analysis of 7 enzymes of the glycolysis pathway which is already known to be affected in human schizophrenia and in the widely-used acute PCP rat model of schizophrenia. The selected enzymes were hexokinase 1 (Hk1), aldolase C (Aldoc), triosephosphate isomerase (Tpi1), glyceraldehyde-3-phosphate dehydrogenase (Gapdh), phosphoglycerate mutase 1 (Pgam1), phosphoglycerate kinase 1 (Pgk1) and enolase 2 (Eno2). The levels of these enzymes were analyzed using SRM in frontal cortex from brain tissue of PCP treated rats. Results: Univariate analyses showed statistically significant altered levels of Tpi1 and alteration of Hk1, Aldoc, Pgam1 and Gapdh with borderline significance in PCP rats compared to controls. Most interestingly, multivariate analysis which considered the levels of all 7 enzymes simultaneously resulted in generation of a bi-dimensional chart that can distinguish the PCP rats from the controls. Conclusions: This study not only supports PCP treated rats as a useful preclinical model of schizophrenia, but it also establishes that SRM mass spectrometry could be used in the development of multiplex classification tools for complex psychiatric disorders such as schizophrenia.

Impaired neuronal network function is a hallmark of neurodevelopmental and neurodegenerative disorders such as autism, schizophrenia, and Alzheimer's disease and is typically studied using genetically modified cellular and animal models. Weak predictive capacity and poor translational value of these models urge for better human derived in vitro models. The implementation of human induced pluripotent stem cells (hiPSCs) allows studying pathologies in differentiated disease-relevant and patient-derived neuronal cells. However, the differentiation process and growth conditions of hiPSC-derived neurons are non-trivial. In order to study neuronal network formation and (mal) function in a fully humanized system, we have established an in vitro co-culture model of hiPSC-derived cortical neurons and human primary astrocytes that recapitulates neuronal network synchronization and connectivity within three to four weeks after final plating. Live cell calcium imaging, electrophysiology and high content image analyses revealed an increased maturation of network functionality and synchronicity over time for co-cultures compared to neuronal monocultures. The cells express GABAergic and glutamatergic markers and respond to inhibitors of both neurotransmitter pathways in a functional assay. The combination of this co-culture model with quantitative imaging of network morphofunction is amenable to high throughput screening for lead discovery and drug optimization for neurological diseases. The research leading to these results has received support from the Innovative Medicines Initiative Joint Undertaking under grant agreement no. 115439, resources of which are composed of financial contribution from the European Union's Seventh Framework Programme (FP7/2007-2013) and EFPIA companies in kind contribution. This publication reflects only the author's views and neither the IMI JU nor EFPIA nor the European Commission are liable for any use that may be made of the information contained therein. This work was supported by the University of Antwerp (WDV: TTBOF 29267), the Institute for the Promotion of Innovation by Science and Technology (IWT) (JK GM PV BB: no. 120511; JD WDV: no. 140775; PV WDV: no. 150003), by the Fonds Wetenschappelijk Onderzoek (FWO) (MV: no. 11ZF116N) in Flanders and by the 7th Framework Program of the European Commission Marie Curie NAMASEN Network Grant no. 264872 (TO). The authors thank the Janssen Neuroscience department for scientific advice and helpful discussions and Andreas Ebneth for critical review of the manuscript.

The interaction of ghrelin, a 28-residue acylated peptide, with the growth hormone secretagogue receptor 1a (GHS-R1a) has been studied mostly in cells expressing a recombinant GHS-R1a. As awareness is growing on the importance to study G protein-coupled receptors in a natural environment, we studied the effect of ghrelin in the human hepatocellular HepG2 cell line because it has been described in literature to respond to ghrelin. Despite extensive efforts, we were not able to confirm mRNA expression of GHS-R1a by reverse transcription PCR, radioligand binding, or ghrelin-induced GHS-R1a receptor activation; therefore, we conclude that HepG2 cells do not express GHS-R1a. On the other hand, we confirmed a modest effect of ghrelin on the up-regulation of IRS-1 phosphorylation, which might suggest the existence of an alternative ghrelin receptor in HepG2 cells.

Tetrodotoxin-resistant (TTX-R) sodium currents have been proposed to underlie sensory neuronal hyperexcitability in acute inflammatory models, but their role in chronic models is unknown. Since no pharmacological tools to separate TTX-R currents are available, this study employs Na(v)1.8 and Na(v)1.9 null mice to evaluate these currents roles in a chronic hyperexcitability model after the resolution of an inflammatory insult. Transient jejunitis was induced by infection with Nippostrongylus brasiliensis (Nb) in Na(v)1.9 and Na(v)1.8 null, wild-type and naive mice. Retrogradely labelled dorsal root ganglia (DRG) neurons were harvested on day 20-24 post-infection for patch clamp recording. Rheobase and action potential (AP) parameters were recorded as measures of excitability, and Na(v)1.9 and Na(v)1.8 currents were recorded. DRG neuronal excitability was significantly increased in post-infected mice compared to sham animals, despite the absence of ongoing inflammation (sham = 1.9 +/- 0.3, infected = 3.6 +/- 0.7 APs at 2x rheobase, P = 0.02). Hyperexcitability was associated with a significantly increased amplitude of TTX-R currents. Hyperexcitability was maintained in Na(v)1.9(-/-) mice, but hyperexcitability was absent and APs were blunted in Na(v)1.8(-/-) mice. This study identifies a critical role for Na(v)1.8 in chronic post-infectious visceral hyperexcitability, with no contribution from Na(v)1.9. Nb infection-induced hyperexcitability is not observed in Na(v)1.8(-/-) mice, but is still present in Na(v)1.9(-/-) mice. It is not clear whether hyperexcitability is due to a change in the function of Na(v)1.8 channels or a change in the number of Na(v)1.8 channels.

The bowel flora is implicated in Crohn's disease (CD) pathogenesis but its precise role is still unclear. Several non-mutually exclusive hypotheses have been proposed: an unidentified persistent pathogen; excessive bacterial translocation; an immune system abnormality in response to normal bacteria; or a breakdown in the balance between protective and harmful bacteria. These hypotheses can be tested by identifying bacteria in specific microscopic bowel structures or lesions. The present paper describes a novel technique to assess bacterial flora diversity in bowel biopsies, by combining laser capture microdissection with broad-range 16S rDNA sequencing. Fifty-four samples comprising histologically normal and pathological mucosa, MALT, ulcers, submucosal lymphangiectasias, epithelioid granulomas, and lymph nodes were microdissected out of 30 bowel biopsies from five CD patients. Bacterial 16S rDNA was successfully amplified by PCR in all samples, and PCR products from 15 samples were selected for cloning and sequence analysis. A total of 729 bacterial DNA sequences were analysed, which could be attributed to six different phyla (Proteobacteria, Firmicutes, Bacteroidetes, Actinobacteria, Fusobacteria, and Planctomycetes). DNA from typical bowel bacteria (Enterobacteriaceae, Clostridiales, Bacteroidetes, Fusobacteria) was detected in all microdissected areas. It was thus convincingly demonstrated that 16S rDNA sequencing can be combined with microdissection to study the bowel flora. However, no specific persistent pathogen causal for CD was identified. The results suggest that Enterobacteriaceae may initiate or colonize ulcers in CD. Translocation of bacteria through established mucosal lesions or as a result of increased permeability may be involved in the evolution towards chronic inflammation and in the establishment of persistent lesions. Further study is needed to confirm these preliminary findings.

Vagal afferent neurons are thought to convey primarily physiological information, whereas spinal afferents transmit noxious signals from the viscera to the central nervous system. To elucidate molecular identities for these different properties, we compared gene expression profiles of neurons located in nodose ganglia (NG) and dorsal root ganglia (DRG) in mice. Intraperitoneal administration of Alexa Fluor-488-conjugated cholera toxin B allowed enrichment for neurons projecting to the viscera. Fluorescent neurons in DRG (from T10 to T13) and NG were isolated using laser-capture microdissection. Gene expression profiles of these afferent neurons, obtained by microarray hybridization, were analyzed using multivariate spectral map analysis, significance analysis of microarrays (SAM) algorithm, and fold-difference filtering. A total of 1,996 genes were differentially expressed in DRG vs. NG, including 41 G protein-coupled receptors and 60 ion channels. Expression profiles obtained on laser-captured neurons were contrasted to those obtained on whole ganglia, demonstrating striking differences and the need for microdissection when studying visceral sensory neurons because of dilution of the signal by somatic sensory neurons. Furthermore, we provide a detailed catalog of all adrenergic and cholinergic, GABA, glutamate, serotonin, and dopamine receptors; voltage-gated potassium, sodium, and calcium channels; and transient receptor potential cation channels present in afferents projecting to the peritoneal cavity. Our genome-wide expression profiling data provide novel insight into molecular signatures that underlie both functional differences and similarities between NG and DRG sensory neurons. Moreover, these findings will offer novel insight into mode of action of pharmacological agents modulating visceral sensation.

This study aimed to determine, quantify and explain regional differences in the relaxant response to the selective 5-HT1 and 5-HT7 receptor agonist 5-carboxamidotryptamine (5-CT) throughout the canine stomach. Longitudinal muscle strips from eight gastric corpus regions and six antrum regions were mounted for isotonic measurement. The 5-CT-induced relaxation was examined on a prostaglandin F2α-induced submaximal response, expressed as percentage of this response and fitted to the operational model of agonism (OMOA). 5-HT7 receptor messenger RNA (mRNA) expression was compared by means of quantitative PCR. 5-CT inhibited PGF2α-induced tonic contraction (corpus) and increase of phasic contraction amplitude (antrum). The consistent antagonism produced by the selective 5-HT7 receptor antagonist SB-269970 (10 nM, pA2 estimates 8.2–8.9) confirmed that in every region, the inhibition by 5-CT was 5-HT7 receptor mediated. However, variation in the maximum effect (61–108%) and pEC50 (6.4–8.6) was observed throughout the different regions. The OMOA explained these differences as differences in the efficacy parameter τ (ratio of receptor density and coupling efficiency; log τ estimates ranging from 0.1 to 2.1). The log τ gradient decreases going from the lesser to the greater curvature. A proportional difference (68%) in the relative expression of 5-HT7 receptor mRNA between the lesser and the greater curvature indicates that differences in receptor density contribute to the observed functional differences. This study illustrates that 5-HT7 receptors are present throughout the ventral wall of the canine stomach, but the efficacy (expressed as log τ) is clearly greater close to the lesser curvature. Differences in 5-HT7 receptor expression at least partially explain the functional differences. British Journal of Pharmacology (2004) 143, 331–342. doi:10.1038/sj.bjp.0705922

Corticotropin-releasing factor (CRF) plays an important role in mediating central and peripheral responses to stress. Alterations in CRF system activity have been linked to a number of psychiatric disorders, including anxiety and depression. Aim of this study was to elucidate homeostatic mechanisms induced by lifelong elevated CRF levels in the brain. We therefore profiled gene expression in several brain areas of transgenic mice overexpressing CRF (CRF-OE), a model for chronic stress. Several genes showed altered expression levels in CRF-OE mice when compared to their wild type littermates and were confirmed by quantitative PCR. Differences in gene expression profiles revealed the presence of previously unrecognized homeostatic mechanisms in CRF-OE animals. These included changes in glucocorticoid signaling, as exemplified by changes in 11beta-hydroxysteroid dehydrogenase type 1, FK506 binding protein 5 and serum/glucocorticoid kinase. Alterations in expression of genes involved in myelination (myelin, myelin-associated glycoprotein), cell proliferation and extracellular matrix formation (Edg2, Fgfr2, decorin, brevican) suggest changes in the dynamics of neurogenesis in CRF-OE. Pronounced changes in neurotensin (NT) receptors 1 and 2 mRNA were identified. Overall downregulation of NT receptors in CRF-OE animal was substantiated by receptor binding studies. Pronounced neurotensin receptor downregulation was observed for NT type 1 receptors in limbic brain areas, suggesting that NT could be implicated in some of the effects attributed to CRF overexpression. These data show that lifelong exposure to excessive CRF leads to adaptive changes in the brain which could play a role in some of the behavioral and physiological alterations seen in these animals.

Corticotropin-releasing factor (CRF) plays a central role in the regulation of the hypothalamic-pituitary-adrenal axis, mediating endocrine and behavioral responses to various stressors. Two high-affinity receptors for CRF have been described. Although many of the intracellular signaling pathways activated by CRF have been studied extensively, our knowledge of transcriptional responses downstream of the CRF receptor 1 (CRFR1) is still limited. To elucidate gene networks regulated by CRF and CRFR1, we applied microarray technology to explore transcriptional response to CRF stimulation. Therefore, mouse pituitary-derived AtT-20 cells were exposed continuously to CRF either in the presence or absence of the specific CRFR1 antagonist R121919. Transcriptional responses to different treatments were studied in a time course ranging from 0.5 to 24 h. Microarray data were analyzed using classic microarray data analysis tools such as correspondence factor analysis, cluster analysis, and fold-change filtering. Furthermore, spectral map analysis was applied, a recently introduced unsupervised multivariate analysis method. A broad and transient transcriptional response to CRF was identified that could be blocked by the antagonist. This way, several known CRF-induced target genes and novel CRF responsive genes were identified. These include transcription factors such as cAMP-responsive element modulator (7x increased), secreted peptides such as cholecystokinin (1.5x), and proteins involved in modulating intracellular signaling, such as regulator of G-protein signaling 2 (11x). Up-regulation of many of these genes can be explained as negative feedback, attenuating CRF-activated pathways. In addition, spectral map analysis proved to be a promising new tool for microarray data analysis.

The ETV6 gene (first identified asTEL )i s a frequent target of chromosomal translocations in both myeloid and lymphoid leukemias. At present, more than 40 distinct translocations have been cytogenetically described, of which 13 have now also been characterized at the molecular level. These studies revealed the generation of in-frame fusion genes between different domains of ETV6 and partner genes encoding either kinases or transcription factors. However, in a number of cases—including a t(6;12)(q23;p13), the recurrent t(5;12)(q31;p13), and some cases of the t(4;12)(q11-q12;p13) described in this work—functionally significant fusions could not be identified, raising the question as to what leukemogenic mechanism is implicated in these cases. To investigate this, we have evaluated the genomic regions at 4q11-q12 and 5q31, telomeric to the breakpoints of the t(4; 12)(q11-q12;p13) and t(5;12)(q31;p13). The homeobox gene GSH2 at 4q11-q12 and the IL-3/CSF2 locus at 5q31 were found to be located close to the respective breakpoints. In addition, GSH2 and IL-3 were found to be ectopically expressed in the leukemic cells, suggesting that expression of GSH2 and IL-3 was deregulated by the translocation. Our results indicate that, besides the generation of fusion transcripts, deregulation of the expression of oncogenes could be a variant leukemogenic mechanism for translocations involving the 5* end of ETV6, especially for those translocations lacking functionally significant fusion transcripts. (Blood. 2002;99:1776-1784)

The Janus kinase family of proteins, with four mammalian members (JAK1, JAK2, JAK3 and TYK2), plays an essential role in the signal transduction pathway from non-catalytic cytokine receptors to the nucleus. We recently reported the involvement of ETV6-JAK2 fusion genes in the development of leukemia of both lymphoid and myeloid origin. Dominant missense mutations of hopscotch, a Drosophila JAK homologue, causing leukemia-like defects were described. One of these mutations affected a conserved residue of the kinase- like JH2 domain and the introduction of this mutation in murine Jak2 resulted in the constitutional activation of its kinase activity. In order to further analyze its role in leukemogenesis, we cloned human JAK2 and determined its genomic organization. Twenty-four exons spanning a region of approximately 150 kb were identified. A mutation analysis of the exons 13 to 19, encoding the kinase-like JH2 domain failed to detect activating mutations in leukemia samples, suggesting that this is a rare event in human leukemia.

Recent reports have demonstrated fusion of the TEL gene on 12p13 to the JAK2 gene on 9p24 in human leukemias. Three variants have been identified that fuse the TEL pointed (PNT) domain to (i) the JAK2 JH1-kinase domain, (ii) part of and (iii) all of the JH2 pseudokinase domain. We report that all of the human TEL/JAK2 variants, and a human/mouse chimeric hTEL/mJAK2(JH1) fusion gene, transform the interleukin-3 (IL-3)-dependent murine hematopoietic cell line Ba/F3 to IL-3-independent growth. Transformation requires both the TEL PNT domain and JAK2 kinase activity. Furthermore, all TEL/JAK2 variants strongly activated STAT 5 by phosphotyrosine Western blots and by electrophoretic mobility shift assays (EMSA). Mice (n = 40) transplanted with bone marrow infected with the MSCV retrovirus containing either the hTEL/mJAK2(JH1) fusion or its human counterpart developed a fatal mixed myeloproliferative and T-cell lymphoproliferative disorder with a latency of 2-10 weeks. In contrast, mice transplanted with a TEL/JAK2 mutant lacking the TEL PNT domain (n = 10) or a kinase-inactive TEL/JAK2(JH1) mutant (n = 10) did not develop the disease. We conclude that all human TEL/JAK2 fusion variants are oncoproteins in vitro that strongly activate STAT 5, and cause lethal myelo- and lymphoproliferative syndromes in murine bone marrow transplant models of leukemia.

Translocations in hematologic disease of myeloid or lymphoid origin with breakpoints at chromosome band 12p13 frequently result in rearrangements of the Ets variant gene 6 (ETV6). As a consequence either the ETS DNA-binding domain or the Helix-Loop-Helix (HLH) oligomerization domain of ETV6 is fused to different partner genes. We show here that a t(9; 12)(p24; p13) in a case of early pre-B acute lymphoid leukemia and a t(9; 15; 12)(p24; q15; p13) in atypical chronic myelogenous leukemia in transformation involve the ETV6 gene at 12p13 and the JAK2 gene at 9p24. In each case different fusion mRNAs were found, with only one resulting in an open reading frame for a chimeric protein consisting of the HLH oligomerization domain of ETV6 and the protein tyrosine kinase (PTK) domain of JAK2. The cloning of the complete human JAK2 coding and genomic sequences and of the genomic junction fragments of the translocations allowed a characterization of the different splice events leading to the various mRNAs. JAK2 plays a central role in non–protein tyrosine kinase receptor signaling pathways, which could explain its involvement in malignancies of different hematologic lineages. Besides hop in Drosophila no member of the JAK family has yet been implicated in tumorigenesis.

In Saccharomyces cerevisiae, most of the LYS structural genes have been identified except the genes encoding homocitrate synthase and alpha-aminoadipate aminotransferase. Expression of several LYS genes responds to an induction mechanism mediated by the product of LYS14 and an intermediate of the pathway, alpha-aminoadipate semialdehyde (alpha AASA) as an inducer. This activation is modulated by the presence of lysine in the growth medium leading to an apparent repression. Since the first enzyme of the pathway, homocitrate synthase, is feedback inhibited by lysine, it could be a major element in the control of alpha AASA supply. During the sequencing of chromosome IV of S. cerevisiae, the sequence of ORF D1298 showing a significant similarity with the nifV gene of Azotobacter vinelandii was reported. Disruption and overexpression of ORF D1298 demonstrate that this gene, named LYS20, encodes a homocitrate synthase. The disrupted segregants are able to grow on minimal medium and exhibit reduced but significant homocitrate synthase indicating that this activity is catalysed by at least two isoenzymes. We have also shown that the product of LYS20 is responsible for the greater part of the lysine production. The different isoforms are sensitive to inhibition by lysine but only the expression of LYS20 is strongly repressed by lysine. The N-terminal end of homocitrate synthase isoform coded by LYS20 contains no typical mitochondrial targeting sequence, suggesting that this enzyme is not located in the mitochondria.

(serotonin receptor 6) as a candidate geneto test for associations with obesity since earlier studies haveshown that mice with a disrupted serotonin receptor are lessprone to become obese on a high-fat diet. We genotypedthree tagSNPs (rs6658108, rs6699866 and rs9659997) andincluded one multimarker prediction test to cover the geneticinformation of the entire gene in our Belgian study popu-lation (1089 obese cases and 308 lean controls). Statisticalanalysis revealed no significant associations with obesity forall variants that were tested. Our data therefore indicate thatcommon

Mammalian microtubule plus-end tracking proteins (+TIPs) specifically associate with the ends of growing microtubules. +TIPs are involved in many cellular processes, including mitosis, cell migration and neurite extension. Navigators are mammalian homologues of the C. elegans unc-53 protein, an ATPase that has been linked to the migration and outgrowth of muscles, axons and excretory canals. Here we show that all three mammalian Navigators are +TIPs, consistent with a previous study on Navigator 1 (NAV1) (Martinez-Lopez et al., Mol Cell Neurosci 2005;28:599–612). Overexpression of GFP-tagged Navigators causes displacement of CAP_GLY-motif containing +TIPs, such as CLIP-170, from microtubule ends, suggesting that the Navigator-binding sites on microtubule ends overlap with those of the CAP_GLY-motif proteins. In interphase cells, mammalian Navigators also prominently localize to centrosomes, a localization that does not depend on an intact microtubule network. Fluorescence recovery after photobleaching (FRAP) experiments indicate that NAV1 associates with intracellular structures other than microtubules or centrosomes. Expression of GFP-tagged Navigators induces the formation of neurite-like extensions in non-neuronal cells, showing that Navigators can dominantly alter cytoskeletal behavior. For NAV1 this function depends on its ATPase activity; it is not achieved by a classical type of MT bundling and stabilization. Combined our data suggest that Navigators are +TIPs that can reorganize the cytoskeleton to guide cell shape changes. Our data are consistent with a role for Navigators in neurite outgrowth. Cell Motil. Cytoskeleton 2009. © 2009 Wiley-Liss, Inc.

CRF-induced ERK phosphorylation has been shown to be an important mechanism underlying expression of pro-opiomelanocortin, a key precursor molecule in the hypothalamic pituitary adrenal axis. In AtT20 cells, CRF signalling has been investigated but the mechanism behind CRF-induced ERK activity is not fully understood. This paper elucidates the signalling cascade involved in this phenomenon. Involvement of CRF(1) receptor on ERK phosphorylation was shown by using CRF and urocortin 1. The lack of inhibitory effect of pertussis toxin and BAPTA-AM excluded involvement of G(i)-coupling and calcium mobilization respectively. In contrast, the process is suggested to be driven by cAMP since treatment of AtT20 cells with forskolin triggered strong ERK phosphorylation. Treatment with PKA inhibitors had a minor effect on CRF-induced ERK signalling while phosphorylation of CREB was completely abolished. This ruled out involvement of PKA and suggested a role for exchange protein directly activated by cAMP (EPAC). Moreover, an activator of EPACs 8-(4-methoxyphenylthio)-2'-O-methyladenosine-3',5'-cyclic monophosphate mimicked CRF-induced ERK phosphorylation. Gene expression analysis showed high levels of EPAC2 mRNA and protein but low levels of EPAC1. Knockdown of EPAC2 expression by the use of specific siRNAs abolished CRF- and forskolin-induced ERK phosphorylation. The current study demonstrates a clear cAMP-dependent but PKA-independent mechanism underlying CRF-induced ERK activity that proceeds via EPAC2 signalling. Further research will provide more insight in the role of EPAC2 in CRF signalling.

Considerable interest has been focused on inducing RNA interference (RNAi) in neurons to study gene function and identify new targets for disease intervention. Although small interfering RNAs (siRNAs) have been used to silence genes in neurons, in vivo delivery of RNAi remains a major challenge limiting its applications. We have developed a highly efficient method for in vivo gene silencing in dorsal root ganglia (DRG) using replication-defective herpes simplex viral (HSV-1) vectors. HSV-mediated delivery of short-hairpin RNA (shRNA) targeting reporter genes resulted in highly effective and specific silencing in neuronal and non-neuronal cells in culture and in the DRG of mice in vivo including in a transgenic mouse model. We further establish proof of concept by demonstrating in vivo silencing of the endogenous trpv1 gene. These data are the first to show silencing in DRG neurons in vivo by vector-mediated delivery of shRNA. Our results support the utility of HSV vectors for gene silencing in peripheral neurons and the potential application of this technology to the study of nociceptive processes and in pain gene target validation studies.

The TRPA1 channel is activated by a number of pungent chemicals, such as allylisothiocyanate, present in mustard oil and thiosulfinates present in garlic. Most of the known activating compounds contain reactive, electrophilic chemical groups, reacting with cysteine residues in the active site of the TRPA1 channel. This covalent modification results in activation of the channel and has been shown to be reversible for several ligands. Commonly used tear gasses CN, CR and CS are also pungent chemicals, and in this study we show that they are extremely potent and selective activators of the human TRPA1 receptor. To our knowledge, these are the most potent TRPA1 agonists known to date. The identification of the molecular target for these tear gasses may open up possibilities to alleviate the effects of tear gasses via treatment with TRPA1 antagonists. In addition these results may contribute to the basic knowledge of the TRPA1 channel that is gaining importance as a pharmacological target.

The sirtuin SIRT1 is an important regulator of energy metabolism through its impact on glucose and lipid metabolism and therefore we tested the hypothesis that genetic variation in SIRT1 may have an effect on adiposity in a Belgian case/control association study. This study included 1,068 obese patients (BMI ¡Ý 30 kg/m2) from the outpatient obesity clinic and 313 lean controls (BMI between 18.5 and 25 kg/m2). Anthropometrics were assessed by classical methods and visceral (VFA), subcutaneous (SFA) and total abdominal (TFA) fat areas were determined by a CT scan. The extent of linkage disequilibrium in SIRT1 allowed us to reduce the number of SNPs to two, sufficient to cover the entire gene. The two tagSNPs (rs7069102 and rs3818292) were analyzed by LightSNiP assays in all subjects. Rs3818292 genotypes were similarly distributed in cases and controls, whereas rs7069102 was different for the additive (P = 0.007) and dominant (P = 0.01) model. The variant C-allele of rs7069102 reduced obesity risk with an OR of 0.74 (P = 0.025; 95% CI 0.57¨C0.96) under a dominant model. In obese male subjects, this variant allele was associated with increased waist circumference (P = 0.04), WHR (P = 0.02), TFA (P = 0.03) and VFA (P = 0.005) (dominant model; adjusted for age and BMI). Rs3818292 was related to VFA (P = 0.005; adjusted for age and BMI) in obese males while in obese women, no significant associations were detected. Our data suggest that genetic variation in SIRT1 increases the risk for obesity, and that SIRT1 genotype correlates with visceral obesity parameters in obese men.

The migration of cells and the extension of cellular processes along pathways to their defined destinations are crucial in the development of higher organisms. Caenorhabditis elegans unc-53 plays an important role in cell migration and the outgrowth of cellular processes such as axons. To gain further insight into the biological function of unc53H2, a recently identified mammalian homologue of unc-53, we have generated mice carrying a mutation of unc53H2 and provide evidence that unc53H2 is involved in neuronal development and, more specifically, the development of different sensory systems. The unc53H2 hypomorphic mouse showed a general impaired acuity of several sensory systems (olfactory, auditory, visual and pain sensation) which in case of the visual system was corroborated by the morphological observation of hypoplasia of the optic nerve. We hypothesize that in analogy with its C. elegans homologue, unc53H2 may play a role in the processes of cellular outgrowth and migration.

We have constructed a detailed map of the genomic region containing the ETS-variant gene 6 (ETV6), involved in translocations and deletions associated with hematologic malignancies. Thirty-eight cosmids were characterized belonging to two contigs spanning 340 kb, and an EcoRl restriction map was developed. The gap between the two contigs, 2 kb in size, was closed by PCR. The contigs contain the complete coding sequence and the 5' and 3' UTRs of ETV6. Eight exons accounting for the ETV6 cDNA sequence were identified. The helix-loop-helix (HLH) motif is coded by exons 3 and 4, whereas exons 6-8 code for the ETS DNA-binding domain. All introns show consensus 5' donor and 3' acceptor splice sites. Introns 1 and 2 span 100 and 82 kb, respectively, and introns 3-7 range from 15 to 1.3 kb. An alternative exon 1 (exon 1B) is localized in intron 2. The 5' end of the ETV6 gene is associated with a CpG island characterized by the presence of four Notl, four Sacll, and three BssHll recognition sites and several SP1- and AP2-binding motifs. Alternative polyadenylation at the 3' end of the ETV6 gene generates the three transcripts of 6200, 4300, and 2400 nucleotides, respectively. The ETV6 gene spans 240 kb and is flanked at its 5' and 3' end by D12S1697 and D12S98, respectively. The markers D12S1095 and D12S89 are located in the first intron. Two new DNA polymorphisms were identified in the ETV6 gene, which will be useful for the analysis of loss of heterozygosity reported for the ETV6 gene in leukemia.

Background Major depressive disorder (MDD) is a heterogeneous disease at the level of clinical symptoms, and this heterogeneity is likely reflected at the level of biology. Two clinical subtypes within MDD that have garnered interest are “melancholic depression” and “anxious depression”. Metabolomics enables us to characterize hundreds of small molecules that comprise the metabolome, and recent work suggests the blood metabolome may be able to inform treatment decisions for MDD, however work is at an early stage. Here we examine a metabolomics data set to (1) test whether clinically homogenous MDD subtypes are also more biologically homogeneous, and hence more predictiable, (2) devise a robust machine learning framework that preserves biological meaning, and (3) describe the metabolomic biosignature for melancholic depression. Results With the proposed computational system we achieves around 80 % classification accuracy, sensitivity and specificity for melancholic depression, but only ~72 % for anxious depression or MDD, suggesting the blood metabolome contains more information about melancholic depression.. We develop an ensemble feature selection framework (EFSF) in which features are first clustered, and learning then takes place on the cluster centroids, retaining information about correlated features during the feature selection process rather than discarding them as most machine learning methods will do. Analysis of the most discriminative feature clusters revealed differences in metabolic classes such as amino acids and lipids as well as pathways studied extensively in MDD such as the activation of cortisol in chronic stress. Conclusions We find the greater clinical homogeneity does indeed lead to better prediction based on biological measurements in the case of melancholic depression. Melancholic depression is shown to be associated with changes in amino acids, catecholamines, lipids, stress hormones, and immune-related metabolites. The proposed computational framework can be adapted to analyze data from many other biomedical applications where the data has similar characteristics. Electronic supplementary material The online version of this article (doi:10.1186/s12864-016-2953-2) contains supplementary material, which is available to authorized users.