Widespread Expression Changes Research Articles

Overabundant endocannabinoids in neurons are detrimental to cognitive function.

2-Arachidonoylglycerol (2-AG) is the most prevalent endocannabinoid involved in maintaining brain homeostasis. Previous studies have demonstrated that inactivating monoacylglycerol lipase (MAGL), the primary enzyme responsible for degrading 2-AG in the brain, alleviates neuropathology and prevents synaptic and cognitive decline in animal models of neurodegenerative diseases. However, we show that selectively inhibiting 2-AG metabolism in neurons impairs cognitive function in mice. This cognitive impairment appears to result from decreased expression of synaptic proteins and synapse numbers, impaired long-term synaptic plasticity and cortical circuit functional connectivity, and diminished neurogenesis. Interestingly, the synaptic and cognitive deficits induced by neuronal MAGL inactivation can be counterbalanced by inhibiting astrocytic 2-AG metabolism. Transcriptomic analyses reveal that inhibiting neuronal 2-AG degradation leads to widespread changes in expression of genes associated with synaptic function. These findings suggest that crosstalk in 2-AG signaling between astrocytes and neurons is crucial for maintaining synaptic and cognitive functions and that excessive 2-AG in neurons alone is detrimental to cognitive function.

Evolution of chemosensory tissues and cells across ecologically diverse Drosophilids.

Chemosensory tissues exhibit significant between-species variability, yet the evolution of gene expression and cell types underlying this diversity remain poorly understood. To address these questions, we conducted transcriptomic analyses of five chemosensory tissues from six Drosophila species and integrated the findings with single-cell datasets. While stabilizing selection predominantly shapes chemosensory transcriptomes, thousands of genes in each tissue have evolved expression differences. Genes that have changed expression in one tissue have often changed in multiple other tissues but at different past epochs and are more likely to be cell type-specific than unchanged genes. Notably, chemosensory-related genes have undergone widespread expression changes, with numerous species-specific gains/losses including novel chemoreceptors expression patterns. Sex differences are also pervasive, including a D. melanogaster-specific excess of male-biased expression in sensory and muscle cells in its forelegs. Together, our analyses provide new insights for understanding evolutionary changes in chemosensory tissues at both global and individual gene levels.

FUSCA3-induced AINTEGUMENTA-like 6 manages seed dormancy and lipid metabolism.

FUSCA 3 (FUS3), a seed master regulator, plays critical role in seed dormancy and oil accumulation. However, its downstream regulation mechanisms remain poorly understood. Here, we explored the roles of AINTEGUMENTA-like 6 (AIL6), a seed transcription factor, in these processes. The activation of AIL6 by FUS3 was demonstrated by dual-LUC assay. Seeds of ail6 mutants showed alterations in fatty acid compositions, and both AtAIL6 (AIL6 from Arabidopsis thaliana) and BnaAIL6 (AIL6 from Brassica napus) rescued the phenotype. Over-expression (OE) of AIL6s reversed changes in seed fatty acid composition. Notably, OE lines showed low seed germination rates down to 12% compared to 100% of wild-type Col-0. Transcriptome analysis of the mutant and an OE line indicated widespread expression changes of genes involved in lipid metabolism and phytohormone pathways. In OE mature seeds, GA4 content decreased more than 15-fold, while abscisic acid and indole-3-acetic acid (IAA) contents clearly increased. Exogenous GA3 treatments did not effectively rescue the low germination rate. Nicking seed coats increased germination rates from 25% to nearly 80% while the wild-type rdr6-11 is 100% and 98% respectively, and elongation of storage time also improved seed germination. Furthermore, dormancy imposed by AIL6 was fully released in the della quintuple mutant. Together, our results indicate AIL6 acts as a manager downstream of FUS3 in seed dormancy and lipid metabolism.

EWS::FLI1 and HOXD13 Control Tumor Cell Plasticity in Ewing Sarcoma.

Propagation of Ewing sarcoma requires precise regulation of EWS::FLI1 transcriptional activity. Determining the mechanisms of fusion regulation will advance our understanding of tumor progression. Here we investigated whether HOXD13, a developmental transcription factor that promotes Ewing sarcoma metastatic phenotypes, influences EWS::FLI1 transcriptional activity. Existing tumor and cell line datasets were used to define EWS::FLI1 binding sites and transcriptional targets. Chromatin immunoprecipitation and CRISPR interference were employed to identify enhancers. CUT&RUN and RNA sequencing defined binding sites and transcriptional targets of HOXD13. Transcriptional states were investigated using bulk and single-cell transcriptomic data from cell lines, patient-derived xenografts, and patient tumors. Mesenchymal phenotypes were assessed by gene set enrichment, flow cytometry, and migration assays. We found that EWS::FLI1 creates a de novo GGAA microsatellite enhancer in a developmentally conserved regulatory region of the HOXD locus. Knockdown of HOXD13 led to widespread changes in expression of developmental gene programs and EWS::FLI1 targets. HOXD13 binding was enriched at established EWS::FLI1 binding sites where it influenced expression of EWS::FLI1-activated genes. More strikingly, HOXD13 bound and activated EWS::FLI1-repressed genes, leading to adoption of mesenchymal and migratory cell states that are normally suppressed by the fusion. Single-cell analysis confirmed that direct transcriptional antagonism between HOXD13-mediated gene activation and EWS::FLI1-dependent gene repression defines the state of Ewing sarcoma cells along a mesenchymal axis. Ewing sarcoma tumors are comprised of tumor cells that exist along a mesenchymal transcriptional continuum. The identity of cells along this continuum is, in large part, determined by the competing activities of EWS::FLI1 and HOXD13. See related commentary by Weiss and Bailey, p. 4360.

Transcriptomic profiling of whole blood in 22q11.2 reciprocal copy number variants reveals that cell proportion highly impacts gene expression

22q11.2 reciprocal copy number variants (CNVs) offer a powerful quasi-experimental “reverse-genetics” paradigm to elucidate how gene dosage (i.e., deletions and duplications) disrupts the transcriptome to cause further downstream effects. Clinical profiles of 22q11.2 CNV carriers indicate that disrupted gene expression causes alterations in neuroanatomy, cognitive function, and psychiatric disease risk. However, interpreting transcriptomic signal in bulk tissue requires careful consideration of potential changes in cell composition. We first characterized transcriptomic dysregulation in peripheral blood from reciprocal 22q11.2 CNV carriers using differential expression analysis and weighted gene co-expression network analysis (WGCNA) to identify modules of co-expressed genes. We also assessed for group differences in cell composition and re-characterized transcriptomic differences after accounting for cell type proportions and medication usage. Finally, to explore whether CNV-related transcriptomic changes relate to downstream phenotypes associated with 22q11.2 CNVs, we tested for associations of gene expression with neuroimaging measures and behavioral traits, including IQ and psychosis or ASD diagnosis. 22q11.2 deletion carriers (22qDel) showed widespread expression changes at the individual gene as well as module eigengene level compared to 22q11.2 duplication carriers (22qDup) and controls. 22qDup showed increased expression of 5 genes within the 22q11.2 locus, and CDH6 located outside of the locus. Downregulated modules in 22qDel implicated altered immune and inflammatory processes. Celltype deconvolution analyses revealed significant differences between CNV and control groups in T-cell, mast cell, and macrophage proportions; differential expression of individual genes between groups was substantially attenuated after adjusting for cell composition. Individual gene, module eigengene, and cell proportions were not significantly associated with psychiatric or neuroanatomic traits. Our findings suggest broad immune-related dysfunction in 22qDel and highlight the importance of understanding differences in cell composition when interpreting transcriptomic changes in clinical populations. Results also suggest novel directions for future investigation to test whether 22q11.2 CNV effects on macrophages have implications for brain-related microglial function that may contribute to psychiatric phenotypes in 22q11.2 CNV carriers.

Targeting Neuroinflammation via Purinergic P2 Receptors for Disease Modification in Drug-Refractory Epilepsy.

Treatment of epilepsy remains a clinical challenge, with >30% of patients not responding to current antiseizure drugs (ASDs). Moreover, currently available ASDs are merely symptomatic without altering significantly the progression of the disease. Inflammation is increasingly recognized as playing an important role during the generation of hyperexcitable networks in the brain. Accordingly, the suppression of chronic inflammation has been suggested as a promising therapeutic strategy to prevent epileptogenesis and to treat drug-refractory epilepsy. As a consequence, a strong focus of ongoing research is identification of the mechanisms that contribute to sustained inflammation in the brain during epilepsy and whether these can be targeted. ATP is released in response to several pathological stimuli, including increased neuronal activity within the central nervous system, where it functions as a neuro- and gliotransmitter. Once released, ATP activates purinergic P2 receptors, which are divided into metabotropic P2Y and ionotropic P2X receptors, driving inflammatory processes. Evidence from experimental models and patients demonstrates widespread expression changes of both P2Y and P2X receptors during epilepsy, and critically, drugs targeting both receptor subtypes, in particular the P2Y1 and P2X7 subtypes, have been shown to possess both anticonvulsive and antiepileptic potential. This review provides a detailed summary of the current evidence suggesting ATP-gated receptors as novel drug targets for epilepsy and discusses how P2 receptor–driven inflammation may contribute to the generation of seizures and the development of epilepsy.

Data, Reagents, Assays and Merits of Proteomics for SARS-CoV-2 Research and Testing

As the COVID-19 pandemic continues to spread, thousands of scientists around the globe have changed research direction to understand better how the virus works and to find out how it may be tackled. The number of manuscripts on preprint servers is soaring and peer-reviewed publications using MS-based proteomics are beginning to emerge. To facilitate proteomic research on SARS-CoV-2, the virus that causes COVID-19, this report presents deep-scale proteomes (10,000 proteins; >130,000 peptides) of common cell line models, notably Vero E6, Calu-3, Caco-2, and ACE2-A549 that characterize their protein expression profiles including viral entry factors such as ACE2 or TMPRSS2. Using the 9 kDa protein SRP9 and the breast cancer oncogene BRCA1 as examples, we show how the proteome expression data can be used to refine the annotation of protein-coding regions of the African green monkey and the Vero cell line genomes. Monitoring changes of the proteome on viral infection revealed widespread expression changes including transcriptional regulators, protease inhibitors, and proteins involved in innate immunity. Based on a library of 98 stable-isotope labeled synthetic peptides representing 11 SARS-CoV-2 proteins, we developed PRM (parallel reaction monitoring) assays for nano-flow and micro-flow LC-MS/MS. We assessed the merits of these PRM assays using supernatants of virus-infected Vero E6 cells and challenged the assays by analyzing two diagnostic cohorts of 24 (+30) SARS-CoV-2 positive and 28 (+9) negative cases. In light of the results obtained and including recent publications or manuscripts on preprint servers, we critically discuss the merits of MS-based proteomics for SARS-CoV-2 research and testing.

Regulation of Global Transcription in Escherichia coli by Rsd and 6S RNA.

In Escherichia coli, the sigma factor σ70 directs RNA polymerase to transcribe growth-related genes, while σ38 directs transcription of stress response genes during stationary phase. Two molecules hypothesized to regulate RNA polymerase are the protein Rsd, which binds to σ70, and the non-coding 6S RNA which binds to the RNA polymerase-σ70 holoenzyme. Despite multiple studies, the functions of Rsd and 6S RNA remain controversial. Here we use RNA-Seq in five phases of growth to elucidate their function on a genome-wide scale. We show that Rsd and 6S RNA facilitate σ38 activity throughout bacterial growth, while 6S RNA also regulates widely different genes depending upon growth phase. We discover novel interactions between 6S RNA and Rsd and show widespread expression changes in a strain lacking both regulators. Finally, we present a mathematical model of transcription which highlights the crosstalk between Rsd and 6S RNA as a crucial factor in controlling sigma factor competition and global gene expression.

Integration of the Pokeweed miRNA and mRNA Transcriptomes Reveals Targeting of Jasmonic Acid-Responsive Genes.

The American pokeweed plant, Phytolacca americana, displays broad-spectrum resistance to plant viruses and is a heavy metal hyperaccumulator. However, little is known about the regulation of biotic and abiotic stress responses in this non-model plant. To investigate the control of miRNAs in gene expression, we sequenced the small RNA transcriptome of pokeweed treated with jasmonic acid (JA), a hormone that mediates pathogen defense and stress tolerance. We predicted 145 miRNAs responsive to JA, most of which were unique to pokeweed. These miRNAs were low in abundance and condition-specific, with discrete expression change. Integration of paired mRNA-Seq expression data enabled us to identify correlated, novel JA-responsive targets that mediate hormone biosynthesis, signal transduction, and pathogen defense. The expression of approximately half the pairs was positively correlated, an uncommon finding that we functionally validated by mRNA cleavage. Importantly, we report that a pokeweed-specific miRNA targets the transcript of OPR3, novel evidence that a miRNA regulates a JA biosynthesis enzyme. This first large-scale small RNA study of a Phytolaccaceae family member shows that miRNA-mediated control is a significant component of the JA response, associated with widespread changes in expression of genes required for stress adaptation.

Noise-Induced Dysregulation of Quaking RNA Binding Proteins Contributes to Auditory Nerve Demyelination and Hearing Loss.

Noise exposure causes auditory nerve (AN) degeneration and hearing deficiency, though the proximal biological consequences are not entirely understood. Most AN fibers and spiral ganglion neurons are ensheathed by myelinating glia that provide insulation and ensure rapid transmission of nerve impulses from the cochlea to the brain. Here we show that noise exposure administered to mice of either sex rapidly affects myelinating glial cells, causing molecular and cellular consequences that precede nerve degeneration. This response is characterized by demyelination, inflammation, and widespread expression changes in myelin-related genes, including the RNA splicing regulator Quaking (QKI) and numerous QKI target genes. Analysis of mice deficient in QKI revealed that QKI production in cochlear glial cells is essential for proper myelination of spiral ganglion neurons and AN fibers, and for normal hearing. Our findings implicate QKI dysregulation as a critical early component in the noise response, influencing cochlear glia function that leads to AN demyelination and, ultimately, to hearing deficiency.SIGNIFICANCE STATEMENT Auditory glia cells ensheath a majority of spiral ganglion neurons with myelin, protect auditory neurons, and allow for fast conduction of electrical impulses along the auditory nerve. Here we show that noise exposure causes glial dysfunction leading to myelin abnormality and altered expression of numerous genes in the auditory nerve, including QKI, a gene implicated in regulating myelination. Study of a conditional mouse model that specifically depleted QKI in glia showed that QKI deficiency alone was sufficient to elicit myelin-related abnormality and auditory functional declines. These results establish QKI as a key molecular target in the noise response and a causative agent in hearing loss.

Preadolescent Adversity Programs a Disrupted Maternal Stress Reactivity in Humans and Mice

BackgroundAdverse childhood experiences (ACEs) are one of the greatest predictors of affective disorders for women. Periods of dynamic hormonal flux, including pregnancy, exacerbate the risk for affective disturbance and promote hypothalamic-pituitary-adrenal (HPA) axis dysregulation, a key feature of affective disorders. Little is understood as to how stress experienced in late childhood, defined as preadolescence, alters the programming unique to this period of brain maturation and its interaction with the hormonal changes of pregnancy and postpartum. MethodsPreadolescent female mice were exposed to chronic stress and examined for changes in their HPA axis during pregnancy and postpartum, including assessment of maternal-specific stress responsiveness and transcriptomics of the paraventricular nucleus of the hypothalamus. Translationally, pregnant women with low or high ACEs were examined for their maternal stress responsiveness. ResultsAs predicted, preadolescent stress in mice resulted in a significant blunting of the corticosterone response during pregnancy. Transcriptomic analysis of the paraventricular nucleus revealed widespread changes in expression of immediate early genes and their targets, supporting the likely involvement of an upstream epigenetic mechanism. Critically, in our human studies, the high ACE women showed a significant blunting of the HPA response. ConclusionsThis unique mouse model recapitulates a clinical outcome of a hyporesponsive HPA stress axis, an important feature of affective disorders, during a dynamic hormonal period, and suggests involvement of transcriptional regulation in the hypothalamus. These studies identify a novel mouse model of female ACEs that can be used to examine how additional life adversity may provoke disease risk or resilience.

MiRNA Predictors of Response to DNA Methyltransferase Inhibitors

BackgroundMyelodysplastic syndrome (MDS) is a common disease of the elderly characterized by ineffective maturation of hematopoietic cells manifesting as low blood counts, morphologic atypia, and predisposition to the development of acute leukemia. The only FDA-approved drugs for the treatment of all subytpes of MDS are the DNA methyltransferase inhibitors (DNMTis), azacytidine and decitabine. However, only a minority of patients achieve a hematologic response or better on these agents. We have previously identified a miRNA signature which distinguishes MDS patients from normal controls. We sought to investigate whether miRNA expression might also be predictive of how patients respond to therapy with DNA methyltransferase inhibitors (DNMTis).DesignWe collected paired fresh frozen bone marrow mononuclear cells (BM-MNCs) from 28 patients with MDS both pre and post treatment with DNMTis as well as from 30 normal controls. Following enrichment for miRNAs and other small RNA species using the TruSeq Small RNA sample preparation kit (Illumina, San Diego, CA), miRNAs were sequenced on an Illumina HiSeq 2500. Alignment was performed using Bowtie 2 against reference sequences from mirBASE and differential expression analysis was analyzed using a rank sum score from the following analysis programs: DESeq, edgeR and baySeq. The response to the DNMTis was characterized based upon the following scale: 1 = complete remission, 2 = marrow complete remission, 3 = partial remission, 4 = hematologic improvement, 5 = stable disease, and 6 = progressive disease. Linear regression analysis was conducted using the response score as outcome and miRNA expression value as the predictor.ResultsSeveral differences were found between the control samples and the pre-treatment MDS samples, many of which have been described previously, including hsa-miR-125b, hsa-miR-342, hsa-miR-140, and hsa-miR-150. Not unexpectedly, the expression of numerous miRNAs was significantly altered as a result of treatment with DNMTis. However, there were no significant miRNA expression differences between responders and non-responders in the post-treatment samples and no significant differences between the changes in miRNA expression (pre versus post treatment changes) in responders and non-responders. Interestingly, 5 miRNAs demonstrated significant association between their pre-treatment expression and the degree of response (FDR < 0.05): hsa-miR-125a, hsa-miR-342, hsa-miR-146b, hsa-miR-146a, hsa-miR-423, and hsa-miR-150. These miRNAs share striking overlap in their mRNA targets including key pathway regulators in the p53 pathway as well as numerous growth factors implicated in hematopoietic stem cells as well as hematopoietic stem cell markers.ConclusionThese studies confirm that miRNA expression differences differentiate between MDS and normal controls. The administration of DNMTis results in widespread expression changes regardless of the response to therapy. However, the expression of a small handful of miRNA are positively correlated with the degree of response in MDS pre-treatment samples to DNMTis and therefore may be useful as markers which predict responders to DNMTi therapy in addition to suggesting biological pathways implicated in the mechanism of response. These results await further prospective studies for confirmation. DisclosuresNo relevant conflicts of interest to declare.

The Transcription Factor BATF Controls CD8+ T Cell Effector Differentiation

Following activation by antigen, costimulation, and inflammation, naïve CD8+ T cells initiate a program of clonal expansion and differentiation resulting in wide-spread changes in expression of genes involved in cell-cycle, metabolism, effector function, apoptosis, and homing. Although, several key transcription factors (TFs) have been shown to be important in effector CD8+ T cell differentiation, the precise transcriptional regulation of this differentiation program remains poorly understood. The AP-1 family member BATF plays an important role in regulating differentiation and function in CD4+ Th17 cells, CD4+ follicular helper T cells, and in Ig class switching in B cells. We now show that BATF is also required for effector CD8+ T cell differentiation and regulates a core program of genes involved in effector differentiation. We found that BATF expression is rapidly up-regulated during effector CD8+ T cell differentiation in the mouse model of lymphocytic choriomeningitis virus (LCMV) infection. To examine the role of BATF in effector differentiation, we studied congenically distinct wild type (WT) and BATF knockout (KO) naïve P14 TCR transgenic CD8+ T cells co- transferred into a WT host. Upon infection, the BATF KO cells exhibited a profound, cell-intrinsic defect in effector CD8+ T cell differentiation, with a ∼400-fold decrease in peak number of effector cells. BATF KO effectors showed sustained activation and increased cell death by the mid-expansion phase of the immune response. To address the question of how loss of BATF causes such a severely diminished antigen-specific response, we profiled the binding sites of BATF throughout the genome by chromatin immunoprecipitation and high-throughput sequencing (ChIP-seq) in primary CD8+ effector cells. We found that BATF bound to regulatory regions in many genes critical for effector differentiation, including transcription factors (e.g. Tbx21, Eomes, Prdm1), genes involved in cytokine signaling (e.g. Il12rb2, Il2ra), homing (e.g. Sell, Selp, Ccr9), effector function (e.g. Gzmb, Ifng, Il2), apoptosis (e.g. Bcl2, Bcl2l1, Mcl1), and T cell activation (e.g. Ctla4, Cd247, Tnfrsf4), suggesting a major role for BATF in effector CD8+ T cell differentiation. Indeed, we found that genes bound by BATF were highly significantly overrepresented among genes that changed as a result of naïve CD8+ T cells differentiating into effectors in vivo (P = 10-27). Comparison of gene expression in in vitro WT and BATF KO effectors confirmed that BATF bound genes were perturbed by BATF loss of function. Analysis of the kinetics of gene expression during the first 72 hours of effector differentiation showed that loss of BATF perturbed the temporal sequence of expression of critical transcription factors, such as T-bet and Eomes, and resulted in inappropriately early cytokine expression. This suggests that BATF may be required to coordinate the earliest events in CD8+ T cell effector differentiation. To test this hypothesis, we used in vivo CFSE tracking to follow the early CD8+ T cell response during LCMV infection. We found that while BATF KO CD8+ T cells initiate cell division, there was a dramatic collapse in the ability to sustain proliferation and differentiation as early as day 3 post-infection. These results indicate that BATF ensures the orderly progression of a program of genes required by effector cells, restraining the expression of some and promoting the expression of others. More broadly, our results suggest that BATF may provide a common regulatory infrastructure for the development of effector cells in all T cell lineages. Disclosures:Wherry:Genentech: Patents & Royalties.

Transcriptome analysis shows activation of circulating CD8 + T cells in patients with severe asthma

Although previous studies have implicated tissue CD4(+) T cells in the development and maintenance of the inflammatory response in asthmatic patients, little is known about the role of CD8(+) T cells. There is now accumulating evidence that microRNAs and other noncoding RNAs are important regulators of T-cell function. We sought to use transcriptomics to determine the activation state of circulating CD4(+) and CD8(+) T cells in patients with nonsevere and severe asthma. mRNA and noncoding RNA expression in circulating T cells was measured by means of microarray, quantitative real-time PCR, or both. Comparison of mRNA expression showed widespread changes in the circulating CD8(+) but not CD4(+) T cells from patients with severe asthma. No changes were observed in the CD4(+) and CD8(+) T cells in patients with nonsevere asthma versus those in healthy control subjects. Bioinformatics analysis showed that the changes in CD8(+) T-cell mRNA expression were associated with multiple pathways involved in T-cell activation. As with mRNAs, we also observed widespread changes in expression of noncoding RNA species, including natural antisense, pseudogenes, intronic long noncoding RNAs (lncRNAs), and intergenic lncRNAs in CD8(+) T cells from patients with severe asthma. Measurement of the microRNA expression profile showed selective downregulation of miR-28-5p in CD8(+) T cells and reduction of miR-146a and miR-146b in both CD4(+) and CD8(+) T cells. Severe asthma is associated with the activation of circulating CD8(+) T cells but not CD4(+) T cells. This response is correlated with the downregulation of miR-146a/b and miR-28-5p, as well as changes in the expression of multiple species of lncRNA that might regulate CD8(+) T-cell function.