Transcriptional regulation by cyclic AMP-responsive factors

Emerging mesenchymal tumour types and biases in the era of ubiquitous sequencing

New tumour types are being described at increasing frequency, and most new tumour types are now identified via retrospective review of next-generation sequencing data. This contrasts with the traditional, morphology-based method of identifying new tumour types, and while the sequencing-based approach has accelerated progress in the field, it has also introduced novel and under-recognised biases. Here, we discuss tumour types identified based on morphology, including superficial CD34-positive fibroblastic tumour, pseudoendocrine sarcoma and cutaneous clear cell tumour with melanocytic differentiation and ACTIN::MITF fusion. We also describe tumour types identified primarily by next-generation sequencing, including epithelioid and spindle cell rhabdomyosarcoma, round cell neoplasms with EWSR1::PATZ1 fusion, cutaneous melanocytic tumour with CRTC1::TRIM11 fusion, clear cell tumour with melanocytic differentiation and MITF::CREM fusion and GLI1-altered mesenchymal neoplasms, including nested glomoid neoplasm.

cAMP responsive element modulator α promotes effector T cells in systemic autoimmune diseases

T lymphocytes play a crucial role in adaptive immunity. Dysregulation of T cell-derived inflammatory cytokine expression and loss of self-tolerance promote inflammation and tissue damage in several autoimmune/inflammatory diseases, including systemic lupus erythematosus (SLE) and psoriasis. The transcription factor cAMP responsive element modulator α (CREMα) plays a key role in the regulation of T cell homeostasis. Increased expression of CREMα is a hallmark of the T cell-mediated inflammatory diseases SLE and psoriasis. Notably, CREMα regulates the expression of effector molecules through trans-regulation and/or the co-recruitment of epigenetic modifiers, including DNA methyltransferases (DNMT3a), histone-methyltransferases (G9a) and histone acetyltransferases (p300). Thus, CREMα may be used as a biomarker for disease activity and/or target for future targeted therapeutic interventions.

Single-cell multi-omics sequencing of human spermatogenesis reveals a DNA demethylation event associated with male meiotic recombination

Human spermatogenesis is a highly ordered process; however, the roles of DNA methylation and chromatin accessibility in this process remain largely unknown. Here by simultaneously investigating the chromatin accessibility, DNA methylome and transcriptome landscapes using the modified single-cell chromatin overall omic-scale landscape sequencing approach, we revealed that the transcriptional changes throughout human spermatogenesis were correlated with chromatin accessibility changes. In particular, we identified a set of transcription factors and cis elements with potential functions. A round of DNA demethylation was uncovered upon meiosis initiation in human spermatogenesis, which was associated with male meiotic recombination and conserved between human and mouse. Aberrant DNA hypermethylation could be detected in leptotene spermatocytes of certain nonobstructive azoospermia patients. Functionally, the intervention of DNA demethylation affected male meiotic recombination and fertility. Our work provides multi-omics landscapes of human spermatogenesis at single-cell resolution and offers insights into the association between DNA demethylation and male meiotic recombination.

Analysis of the interaction of a non-canonical twin half-site of Cyclic AMP-Response Element (CRE) with CRE-binding protein

Differential regulation of a gene having either canonical or non-canonical cyclic AMP response element (CRE) in its promoter is primarily accomplished by its interactions with CREB (cAMP-response element binding protein). The present study aims to delineate the mechanism of the CREB-CRE interactions at the Oncostatin-M (osm) promoter by in vitro and in silico approaches. The non-canonical CREosm consists of two half-CREs separated by a short intervening sequence of 9 base pairs. In this study, in vitro binding assays revealed that out of the two CRE half-sites, the right half-CRE was indispensable for binding of CREB, while the left sequence showed weaker binding ability and specificity. Genome-wide modeling and high throughput free energy calculations for the energy-minimized models containing CREB-CREosm revealed that there was no difference in the binding of CREB to the right half of CREosm site when compared to the entire CREosm. These results were in accordance with the in vitro studies, confirming the indispensable role of the right half-CREosm site in stable complex formation with the CREB protein. Additionally, conversion of the right half-CREosm site to a canonical CRE palindrome showed stronger CREB binding, irrespective of the presence or absence of the left CRE sequence. Thus, the present study establishes an interesting insight into the interaction of CREB with a CRE variant located at the far end of a TATA-less promoter of a cytokine-encoding gene, which in turn could be involved in the regulation of transcription under specific conditions.

A novel SMARCA2-CREM fusion expending the molecular spectrum of salivary gland hyalinazing clear cell carcinoma beyond the FET genes

Hyalinizing clear cell carcinoma (HCCC) is a rare salivary gland carcinoma with a generally indolent behavior, characterized by recurrent chromosomal translocation involving EWSR1 (22q12.2) leading to two fusion genes EWSR1::ATF1 or EWSR1::CREM. We report one case of HCCC with a novel SMARCA2::CREM fusion, identified by targeted RNA next generation sequencing by LD-RT-PCR, which has until now never been described in salivary glands. The exon 4 of SMARCA2 is fused to exon 5 of CREM. This fusion has been described previously in only one tumor, a central nervous system tumor (intracranial mesenchymal tumor) but not in other FET::CREB fused tumors. This fusion was confirmed by CREM break-apart FISH and reverse transcriptase polymerase chain reaction (RT-PCR). The tumor cells showed retained expression of INI1, SMARCA2, and SMARCA4 by immunohistochemistry. We compare its clinical, histopathological, immunophenotypic, genetic features with those previously described in HCCC, FET::CREB fusion-positive. Our results added data suggesting that different histomolecular tumor subtypes seem to be included within the terminology "HCCC, FET::CREB fusion-positive," and that further series of cases are needed to better characterize them.

The molecular diversity of plasticity mechanisms underlying memory: An evolutionary perspective

Experience triggers molecular cascades in organisms (learning) that lead to alterations (memory) to allow the organism to change its behavior based on experience. Understanding the molecular mechanisms underlying memory, particularly in the nervous system of animals, has been an exciting scientific challenge for neuroscience. We review what is known about forms of neuronal plasticity that underlie memory highlighting important issues in the field: (1) the importance of being able to measure how neurons are activated during learning to identify the form of plasticity that underlies memory, (2) the many distinct forms of plasticity important for memories that naturally decay both within and between organisms, and (3) unifying principles underlying the formation and maintenance of long-term memories. Overall, the diversity of molecular mechanisms underlying memories that naturally decay contrasts with more unified molecular mechanisms implicated in long-lasting changes. Despite many advances, important questions remain as to which mechanisms of neuronal plasticity underlie memory.

Betanin Dose-Dependently Ameliorates Allergic Airway Inflammation by Attenuating Th2 Response and Upregulating cAMP-PKA-CREB Pathway in Asthmatic Mice

Allergic asthma is a refractory disease that affects hundreds of millions of people worldwide. Betanin is a natural plant-derived nutrient and possesses health-promoting properties. The effects of betanin on allergic asthma remain unknown. Herein, the effects and mechanisms of betanin on allergic asthma were explored in ovalbumin (OVA)-induced BALB/c mice. Betanin in doses of 0, 20, 60, and 180 mg/kg was applied. Peripheral inflammatory cells, IgE, pulmonary pathology, T cell subsets, cytokine levels, protein expressions of the cAMP-PKA-CREB/CREM pathway, and gut microbial profile were measured. The 60 and 180 mg/kg/day betanin doses significantly downregulated IgE, eotaxin, eosinophil infiltration, mucus hyperproduction, and Th2. A 180 mg/kg/day betanin dose also significantly reduced percentages of Th17, Tc17, and Tc2 and Th2- and Th17-signature cytokines and upregulated the cAMP-PKA-CREB pathway. Additionally, 20 mg/kg/day betanin altered the gut microbial profile. In conclusion, betanin dose-dependently alleviated allergic asthma and upregulated the cAMP-PKA-CREB pathway in mice. This study provides a novel nutritional strategy to treat allergic asthma.

Apigenin Isolated from Carduus crispus Protects against H2O2-Induced Oxidative Damage and Spermatogenic Expression Changes in GC-2spd Sperm Cells

Testicular oxidative stress is one of the most common factors underlying male infertility. Welted thistle, Carduus crispus Linn., and its bioactive principles are attracting scientific interest in treating male reproductive dysfunctions. Here, the protective effects of apigenin isolated from C. crispus against oxidative damage induced by hydrogen peroxide (H2O2) and dysregulation in spermatogenesis associated parameters in testicular sperm cells was investigated. Cell viabilities, ROS scavenging effects, and spermatogenic associated molecular expressions were measured by MTT, DCF-DA, Western blotting and real-time RT-PCR, respectively. A single peak with 100% purity of apigenin was obtained in HPLC conditions. Apigenin treated alone (2.5, 5, 10 and 20 µM) did not exhibit cytotoxicity, but inhibited the H2O2-induced cellular damage and elevated ROS levels significantly (p < 0.05 at 5, 10 and 20 µM) and dose-dependently. Further, H2O2-induced down-regulation of antioxidant (glutathione S-transferases m5, glutathione peroxidase 4, and peroxiredoxin 3) and spermatogenesis-associated (nectin-2 and phosphorylated-cAMP response element-binding protein) molecular expression in GC-2spd cells were attenuated by apigenin at both protein and mRNA levels (p < 0.05). In conclusion, our study showed that apigenin isolated from C. crispus might be an effective agent that can protect ROS-induced testicular dysfunctions.

ExTRI: Extraction of transcription regulation interactions from literature

The regulation of gene transcription by transcription factors is a fundamental biological process, yet the relations between transcription factors (TF) and their target genes (TG) are still only sparsely covered in databases. Text-mining tools can offer broad and complementary solutions to help locate and extract mentions of these biological relationships in articles. We have generated ExTRI, a knowledge graph of TF-TG relationships, by applying a high recall text-mining pipeline to MedLine abstracts identifying over 100,000 candidate sentences with TF-TG relations. Validation procedures indicated that about half of the candidate sentences contain true TF-TG relationships. Post-processing identified 53,000 high confidence sentences containing TF-TG relationships, with a cross-validation F1-score close to 75%. The resulting collection of TF-TG relationships covers 80% of the relations annotated in existing databases. It adds 11,000 other potential interactions, including relationships for ~100 TFs currently not in public TF-TG relation databases. The high confidence abstract sentences contribute 25,000 literature references not available from other resources and offer a wealth of direct pointers to functional aspects of the TF-TG interactions. Our compiled resource encompassing ExTRI together with publicly available resources delivers literature-derived TF-TG interactions for more than 900 of the 1500-1600 proteins considered to function as specific DNA binding TFs. The obtained result can be used by curators, for network analysis and modelling, for causal reasoning or knowledge graph mining approaches, or serve to benchmark text mining strategies.

Bayesian identification of candidate transcription factors for the regulation of Aqp2 gene expression

Aquaporin-2 (Aqp2) gene transcription is strongly regulated by vasopressin in the renal collecting duct. However, the transcription factors (TFs) responsible for the regulation of expression of Aqp2 remain largely unknown. We used Bayes' theorem to integrate several -omics data sets to stratify the 1,344 TFs present in the mouse genome with regard to probabilities of regulating Aqp2 gene transcription. Also, we carried out new RNA sequencing experiments mapping the time course of vasopressin-induced changes in the transcriptome of mpkCCD cells to identify TFs that change in tandem with Aqp2. The analysis identified 17 of 1,344 TFs that are most likely to be involved in the regulation of Aqp2 gene transcription. These TFs included eight that have been proposed in prior studies to play a role in Aqp2 regulation, viz., Cebpb, Elf1, Elf3, Ets1, Jun, Junb, Nfkb1, and Sp1. The remaining nine represent new candidates for future studies (Atf1, Irf3, Klf5, Klf6, Mef2d, Nfyb, Nr2f6, Stat3, and Nr4a1). Conspicuously absent is CREB (Creb1), which has been widely proposed to mediate vasopressin-induced regulation of Aqp2 gene transcription (Nielsen S, Frokiaer J, Marples D, Kwon TH, Agre P, Knepper MA. Physiol Rev 82: 205-244, 2002; Kortenoeven ML, Fenton RA. Biochim Biophys Acta 1840: 1533-1549, 2014; Bockenhauer D, Bichet DG. Nat Rev Nephrol 11: 576-588, 2015; Pearce D, Soundararajan R, Trimpert C, Kashlan OB, Deen PM, Kohan DE. Clin J Am Soc Nephrol 10: 135-146, 2015). Instead, another CREB-like TF, Atf1, ranked fourth among all TFs. RNA sequencing time-course experiments showed a rapid increase in Aqp2 mRNA, within 3 h of vasopressin exposure. This response was matched by an equally rapid increase in the abundance of the mRNA coding for Cebpb, which we have shown by chromatin immunoprecipitation-sequencing studies to bind downstream from the Aqp2 gene. The identified TFs provide a roadmap for future studies to understand regulation of Aqp2 gene expression.NEW & NOTEWORTHY Abetted by the advent of systems biology-based ("-omics") techniques in the 21st century, there has been a massive expansion of published data relevant to virtually every physiological question. The authors have developed a large-scale data integration approach based on the application of Bayes'' theorem. In the current work, they integrated 12 different -omics data sets to identify the transcription factors most likely to mediate vasopressin-dependent regulation of transcription of the aquaporin-2 gene.

Toxocara canis Infection Alters lncRNA and mRNA Expression Profiles of Dog Bone Marrow

Bone marrow is the main hematopoietic organ that produces red blood cells, granulocytes, monocyte/macrophages, megakaryocytes, lymphocytes, and myeloid dendritic cells. Many of these cells play roles in the pathogenesis of Toxocara canis infection, and understanding how infection alters the dynamics of transcription regulation in bone marrow is therefore critical for deciphering the global changes in the dog transcriptional signatures during T. canis infection. In this study, long non-coding RNA (lncRNA) and messenger RNA (mRNA) expression profiles in the bone marrow of Beagle dogs infected with T. canis were determined at 12 h post-infection (hpi), 24 hpi, 96 hpi, and 36 days post-infection (dpi). RNA-sequencing and bioinformatics analysis identified 1,098, 984, 1,120, and 1,305 differentially expressed lncRNAs (DElncRNAs), and 196, 253, 223, and 328 differentially expressed mRNAs (DEmRNAs) at 12 h, 24 h, 96 h, and 36 days after infection, respectively. We also identified 29, 36, 38, and 68 DEmRNAs potentially cis-regulated by 44, 44, 51, and 80 DElncRNAs at 12 hpi, 24 hpi, 96 hpi, and 36 dpi, respectively. To validate the sequencing findings, qRT-PCR was performed on 10 randomly selected transcripts. Many altered genes were involved in the differentiation of bone marrow cells. GO of DElncRNAs and GO and KEGG pathway analyses of DEmRNAs revealed alterations in several signaling pathways, including pathways involved in energy metabolism, amino acid biosynthesis and metabolism, Wnt signaling pathway, Huntington's disease, HIF-1 signaling pathway, cGMP–PKG signaling pathway, dilated cardiomyopathy, and adrenergic signaling in cardiomyocytes. These findings revealed that bone marrow of T. canis-infected dogs exhibits distinct lncRNA and mRNA expression patterns compared to healthy control dogs. Our data provide novel insights into T. canis interaction with the definitive host and shed light on the significance of the non-coding portion of the dog genome in the pathogenesis of toxocariasis.

Ser71 Phosphorylation Inhibits Actin-Binding of Profilin-1 and Its Apoptosis-Sensitizing Activity

The essential actin-binding factor profilin-1 (Pfn1) is a non-classical tumor suppressor with the abilities toboth inhibit cellular proliferation and augment chemotherapy-induced apoptosis. Besides actin, Pfn1 interacts with proteins harboring the poly-L-proline (PLP) motifs. Our recent work demonstrated that both nuclear localization and PLP-binding are required for tumor growth inhibition by Pfn1, and this is at least partially due to Pfn1 association with the PLP-containing ENL protein in the Super Elongation Complex (SEC) and the transcriptional inhibition of pro-cancer genes. In this paper, by identifying a phosphorylation event of Pfn1 at Ser71 capable of inhibiting its actin-binding and nuclear export, we provide in vitro and in vivo evidence that chemotherapy-induced apoptotic sensitization by Pfn1 requires its cytoplasmic localization and actin-binding. With regard to tumor growth inhibition byPfn1, our data indicate a requirement for dynamic actin association and dissociation rendered by reversible Ser71phosphorylation and dephosphorylation. Furthermore, genetic and pharmacological experiments showed that Ser71 of Pfn1 can be phosphorylated by protein kinase A (PKA). Taken together, our data provide novel mechanistic insights into the multifaceted anticancer activities of Pfn1 and how they are spatially-defined in the cell and differentially regulated by ligand-binding.

Molecular Pathology of Salivary Gland Neoplasms: Diagnostic, Prognostic, and Predictive Perspective

Salivary gland neoplasms are an uncommon and widely heterogeneous group of tumors. In recent years, there has been considerable progress in efforts to reveal the molecular landscape of these tumors, although it is still limited and appears to be only the tip of the iceberg. Genomic aberrations, especially specific chromosomal rearrangements including CRTC1-MAML2 and CRTC3-MAML2 in mucoepidermoid carcinoma, MYB-NFIB and MYBL1-NFIB fusions in adenoid cystic carcinoma, PLAG1 and HMGA2 alterations in pleomorphic adenoma and carcinoma ex pleomorphic adenoma, ETV6-NTRK3 and ETV6-RET in secretory carcinoma, EWSR1-ATF1 and EWSR1-CREM in clear cell carcinoma, provide new insights into the molecular pathogenesis of various salivary gland neoplasms and help to better classify them. These genetic aberrations primarily serve as diagnostic tools in salivary gland tumor diagnosis; however, some also have promise as prognostic or predictive biomarkers. This review summarizes the latest developments in molecular pathology of salivary gland tumors with a focus on distinctive molecular characteristics.

The CBP KIX domain regulates long-term memory and circadian activity

Background

CREB-dependent transcription necessary for long-term memory is driven by interactions with CREB-binding protein (CBP), a multi-domain protein that binds numerous transcription factors potentially affecting expression of thousands of genes. Identifying specific domain functions for multi-domain proteins is essential to understand processes such as cognitive function and circadian clocks. We investigated the function of the CBP KIX domain in hippocampal memory and gene expression using CBP^KIX/KIX mice with mutations that prevent phospho-CREB (Ser133) binding.

Results

We found that CBP^KIX/KIX mice were impaired in long-term memory, but not learning acquisition or short-term memory for the Morris water maze. Using an unbiased analysis of gene expression in the dorsal hippocampus after training in the Morris water maze or contextual fear conditioning, we discovered dysregulation of CREB, CLOCK, and BMAL1 target genes and downregulation of circadian genes in CBP^KIX/KIX mice. Given our finding that the CBP KIX domain was important for transcription of circadian genes, we profiled circadian activity and phase resetting in CBP^KIX/KIX mice. CBP^KIX/KIX mice exhibited delayed activity peaks after light offset and longer free-running periods in constant dark. Interestingly, CBP^KIX/KIX mice displayed phase delays and advances in response to photic stimulation comparable to wildtype littermates. Thus, this work delineates site-specific regulation of the circadian clock by a multi-domain protein.

Conclusions

These studies provide insight into the significance of the CBP KIX domain by defining targets of CBP transcriptional co-activation in memory and the role of the CBP KIX domain in vivo on circadian rhythms.

Graphical abstract

Insight on Transcriptional Regulation of the Energy Sensing AMPK and Biosynthetic mTOR Pathway Genes

The Adenosine Monophosphate-activated Protein Kinase (AMPK) and the Mechanistic Target of Rapamycin (mTOR) are two evolutionarily conserved kinases that together regulate nearly every aspect of cellular and systemic metabolism. These two kinases sense cellular energy and nutrient levels that in turn are determined by environmental nutrient availability. Because AMPK and mTOR are kinases, the large majority of studies remained focused on downstream substrate phosphorylation by these two proteins, and how AMPK and mTOR regulate signaling and metabolism in normal and disease physiology through phosphorylation of their substrates. Compared to the wealth of information known about the signaling and metabolic pathways modulated by these two kinases, much less is known about how the transcription of AMPK and mTOR pathway genes themselves are regulated, and the extent to which AMPK and mTOR regulate gene expression to cause durable changes in phenotype. Acute modification of cellular systems can be achieved through phosphorylation, however, induction of chronic changes requires modulation of gene expression. In this review we will assemble evidence from published studies on transcriptional regulation by AMPK and mTOR and discuss about the putative transcription factors that regulate expression of AMPK and mTOR complex genes.

Comparison of a Novel Homogeneous Cyclic Amp Assay and a Luciferase Assay for Measuring Stimulating Thyrotropin-Receptor Autoantibodies

OBJECTIVE

Stimulating thyrotropin-receptor antibodies (TSAb) cause Graves' disease (GD). We tested a novel homogeneous fluorescent 3',5' cyclic adenine monophosphate (cAMP) assay for the detection of TSAb in a bioassay.

METHODS

Chinese hamster ovary (CHO) cell lines expressing either a chimeric (MC4) or wild-type (WT) TSH-R were incubated with the adenyl cyclase activator forskolin, a human TSAb monoclonal antibody (M22), and with sera from GD patients. Intracellular cAMP levels were measured using a Bridge-It® cAMP assay, and the results were compared with a luciferase-based bioassay.

RESULTS

Both cell lines were stimulated with forskolin concentrations (0.006-200 µM) in a dose-dependent manner. The linear range in the MC4 and WT cells was 0.8-25 and 3.1-50 µM, respectively. Levels of cAMP and luciferase in forskolin-treated MC4 and WT cells were positively correlated (r = 0.91 and 0.84, both p < 0.001). The 50% maximum stimulatory concentration of forskolin was more than 16-fold higher for the CHO-WT cells than the CHO-MC4 cells in the cAMP assay and 4-fold higher in the luciferase assay. Incubation of both cell lines with M22 (0.006-50 ng/mL) resulted in a dose-dependent increase in cAMP levels with linear ranges for the MC4 and WT cells of 0.8-12.5 and 0.2-3.125 ng/mL, respectively. Comparison of cAMP and luciferase levels in M22-treated MC4 and WT cells also showed a positive correlation (r = 0.88, p < 0.001 and 0.75, p = 0.002). A positive correlation was also noted when using patient samples (r = 0.96, p < 0.001) that were all TSH-R-Ab binding assay positive.

CONCLUSION

The novel, rapid, simple-to-perform cAMP assay provides TSAb-mediated stimulatory results comparable to a luciferase-based bioassay.

The arginine methyltransferase CARM1 represses p300•ACT•CREMτ activity and is required for spermiogenesis

CARM1 is a protein arginine methyltransferase (PRMT) that has been firmly implicated in transcriptional regulation. However, the molecular mechanisms by which CARM1 orchestrates transcriptional regulation are not fully understood, especially in a tissue-specific context. We found that Carm1 is highly expressed in the mouse testis and localizes to the nucleus in spermatids, suggesting an important role for Carm1 in spermiogenesis. Using a germline-specific conditional Carm1 knockout mouse model, we found that it is essential for the late stages of haploid germ cell development. Loss of Carm1 led to a low sperm count and deformed sperm heads that can be attributed to defective elongation of round spermatids. RNA-seq analysis of Carm1-null spermatids revealed that the deregulated genes fell into similar categories as those impacted by p300-loss, thus providing a link between Carm1 and p300. Importantly, p300 has long been known to be a major Carm1 substrate. We found that CREMτ, a key testis-specific transcription factor, associates with p300 through its activator, ACT, and that this interaction is negatively regulated by the methylation of p300 by Carm1. Thus, high nuclear Carm1 levels negatively impact the p300•ACT•CREMτ axis during late stages of spermiogenesis.

Selective Depletion of CREB in Serotonergic Neurons Affects the Upregulation of Brain-Derived Neurotrophic Factor Evoked by Chronic Fluoxetine Treatment

Neurotrophic factors are regarded as crucial regulatory components in neuronal plasticity and are postulated to play an important role in depression pathology. The abundant expression of brain-derived neurotrophic factor (BDNF) in various brain structures seems to be of particular interest in this context, as downregulation of BDNF is postulated to be correlated with depression and its upregulation is often observed after chronic treatment with common antidepressants. It is well-known that BDNF expression is regulated by cyclic AMP response element-binding protein (CREB). In our previous study using mice lacking CREB in serotonergic neurons (Creb1^TPH2CreERT2 mice), we showed that selective CREB ablation in these particular neuronal populations is crucial for drug-resistant phenotypes in the tail suspension test observed after fluoxetine administration in Creb1^TPH2CreERT2 mice. The aim of this study was to investigate the molecular changes in the expression of neurotrophins in Creb1^TPH2CreERT2 mice after chronic fluoxetine treatment, restricted to the brain structures implicated in depression pathology with profound serotonergic innervation including the prefrontal cortex (PFC) and hippocampus. Here, we show for the first time that BDNF upregulation observed after fluoxetine in the hippocampus or PFC might be dependent on the transcription factor CREB residing, not within these particular structures targeted by serotonergic projections, but exclusively in serotonergic neurons. This observation may shed new light on the neurotrophic hypothesis of depression, where the effects of BDNF observed after antidepressants in the hippocampus and other brain structures were rather thought to be regulated by CREB residing within the same brain structures. Overall, these results provide further evidence for the pivotal role of CREB in serotonergic neurons in maintaining mechanisms of antidepressant drug action by regulation of BDNF levels.

Gene Level Regulation of Na,K-ATPase in the Renal Proximal Tubule Is Controlled by Two Independent but Interacting Regulatory Mechanisms Involving Salt Inducible Kinase 1 and CREB-Regulated Transcriptional Coactivators

For many years, studies concerning the regulation of Na,K-ATPase were restricted to acute regulatory mechanisms, which affected the phosphorylation of Na,K-ATPase, and thus its retention on the plasma membrane. However, in recent years, this focus has changed. Na,K-ATPase has been established as a signal transducer, which becomes part of a signaling complex as a consequence of ouabain binding. Na,K-ATPase within this signaling complex is localized in caveolae, where Na,K-ATPase has also been observed to regulate Inositol 1,4,5-Trisphosphate Receptor (IP3R)-mediated calcium release. This latter association has been implicated as playing a role in signaling by G Protein Coupled Receptors (GPCRs). Here, the consequences of signaling by renal effectors that act via such GPCRs are reviewed, including their regulatory effects on Na,K-ATPase gene expression in the renal proximal tubule (RPT). Two major types of gene regulation entail signaling by Salt Inducible Kinase 1 (SIK1). On one hand, SIK1 acts so as to block signaling via cAMP Response Element (CRE) Binding Protein (CREB) Regulated Transcriptional Coactivators (CRTCs) and on the other hand, SIK1 acts so as to stimulate signaling via the Myocyte Enhancer Factor 2 (MEF2)/nuclear factor of activated T cell (NFAT) regulated genes. Ultimate consequences of these pathways include regulatory effects which alter the rate of transcription of the Na,K-ATPase β1 subunit gene atp1b1 by CREB, as well as by MEF2/NFAT.

CD11c-Specific Deletion Reveals CREB as a Critical Regulator of DC Function during the Germinal Center Response

Dendritic cells (DCs) are crucial for the balance between immune response and tolerance, but the molecular mechanism regulating development, differentiation, and homeostasis are poorly understood. The transcriptional activator CREB is involved in regulating different cells of the innate and adaptive immune system and is a transcriptional regulator of development, survival, activation, or proliferation in macrophages, dendritic cells, B cells, and T cells. To directly examine the role of CREB in the regulation of DCs, the CREB gene was targeted for deletion with a CD11c-cre transgene. The deletion of CREB in CD11c⁺ cells did not involve any developmental or systemic defects within DC populations. However, CREB deficiency in CD11c⁺ cells reduced germinal center (GC) B cells in steady state, and immunization with NP-CGG resulted in a reduced formation of GCs, paralleled by the reduced production of IgGs in sera of immunized mice. In conclusion, we demonstrate that CREB expression in CD11c⁺ cells enhances germinal center responses, most likely by altering DC function, which might have implications for autoimmune diseases that are associated with dysregulated GC responses.

Networks of Cultured iPSC-Derived Neurons Reveal the Human Synaptic Activity-Regulated Adaptive Gene Program

Long-term adaptive responses in the brain, such as learning and memory, require synaptic activity-regulated gene expression, which has been thoroughly investigated in rodents. Using human iPSC-derived neuronal networks, we show that the human and the mouse synaptic activity-induced transcriptional programs share many genes and both require Ca²⁺-regulated synapse-to-nucleus signaling. Species-specific differences include the noncoding RNA genes BRE-AS1 and LINC00473 and the protein-coding gene ZNF331, which are absent in the mouse genome, as well as several human genes whose orthologs are either not induced by activity or are induced with different kinetics in mice. These results indicate that lineage-specific gain of genes and DNA regulatory elements affects the synaptic activity-regulated gene program, providing a mechanism driving the evolution of human cognitive abilities.

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The repertoire of human activity-induced genes is expanded lineage specifically

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Temporal expression profiles of many activity-responsive genes are species specific

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Some human orthologs of mouse genes have gained inducibility by synaptic activity

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The human HIC1 gene promoter has gained an activity-responsive regulatory element

Neurons and neuronal activity control gene expression in astrocytes to regulate their development and metabolism

The influence that neurons exert on astrocytic function is poorly understood. To investigate this, we first developed a system combining cortical neurons and astrocytes from closely related species, followed by RNA-seq and in silico species separation. This approach uncovers a wide programme of neuron-induced astrocytic gene expression, involving Notch signalling, which drives and maintains astrocytic maturity and neurotransmitter uptake function, is conserved in human development, and is disrupted by neurodegeneration. Separately, hundreds of astrocytic genes are acutely regulated by synaptic activity via mechanisms involving cAMP/PKA-dependent CREB activation. This includes the coordinated activity-dependent upregulation of major astrocytic components of the astrocyte-neuron lactate shuttle, leading to a CREB-dependent increase in astrocytic glucose metabolism and elevated lactate export. Moreover, the groups of astrocytic genes induced by neurons or neuronal activity both show age-dependent decline in humans. Thus, neurons and neuronal activity regulate the astrocytic transcriptome with the potential to shape astrocyte-neuron metabolic cooperation.

Crystal structures reveal a new and novel FoxO1 binding site within the human glucose-6-phosphatase catalytic subunit 1 gene promoter

Human glucose-6-phosphatase plays a vital role in blood glucose homeostasis and holds promise as a therapeutic target for diabetes. Expression of its catalytic subunit gene 1 (G6PC1) is tightly regulated by metabolic-response transcription factors such as FoxO1 and CREB. Although at least three potential FoxO1 binding sites (insulin response elements, IREs) and one CREB binding site (cAMP response element, CRE) within the proximal region of the G6PC1 promoter have been identified, the interplay between FoxO1 and CREB and between FoxO1 bound at multiple IREs has not been well characterized. Here we present the crystal structures of the FoxO1 DNA binding domain in complex with the G6PC1 promoter. These complexes reveal the presence of a new non-consensus FoxO1 binding site that overlaps the CRE, suggesting a mutual exclusion mechanism for FoxO1 and CREB binding at the G6PC1 promoter. Additional findings include (i) non-canonical FoxO1 recognition sites, (ii) incomplete FoxO1 occupancies at the available IRE sites, and (iii) FoxO1 dimeric interactions that may play a role in stabilizing DNA looping. These findings provide insight into the regulation of G6PC1 gene transcription by FoxO1, and demonstrate a high versatility of target gene recognition by FoxO1 that correlates with its diverse roles in biology.

CREM Alpha Enhances IL-21 Production in T Cells In Vivo and In Vitro

The cAMP-responsive element modulator alpha (CREMα) plays a role in autoimmunity and, in particular, in systemic lupus erythematosus. CREMα negatively regulates IL-2 transcription and activates IL-17 expression by direct transcriptional mechanisms. To understand the role of CREM in autoimmunity, we recently generated a mouse with a transgenic overexpression of CREMα selectively in T cells. This mouse is characterized by enhanced IL-17 and IL-21 expression. We, herein, dissect the transcriptional mechanisms of enhanced IL-21 transcription in these mice. T cells of CREMα transgenic mice display an enhanced binding of CREMα to the CD3ζ chain promoter resulting in decreased CD3ζ chain expression. This is accompanied by a decreased excitation threshold and enhanced Ca²⁺ influx, which is known to induce IL-21 expression via NFATc2 activation. However, CREMα directly binds to cAMP-response element (CRE) half-site within the Il-21 promoter, which results in enhanced promoter activity shown by promoter reporter assays. CREMα-induced IL-21 transcription is not abrogated in the presence of cyclosporine A but depends on an intact CRE site within the IL-21 promoter, which suggests that CREM largely enhances IL-21 expression by direct transcriptional regulation. IL-21 transcription is critical for IL-17 generation in these mice, since IL-21 receptor blockade downregulates IL-17 transcription to wild-type levels. Finally, this is of functional relevance since CREMα transgenic mice display enhanced disease activity in dextran sodium sulfate-induced colitis accompanied by higher local IL-21 expression. Thus, we describe two novel mechanisms of CREMα-dependent IL-21 transcription. Since T cells of systemic lupus erythematosus patients are characterized by enhanced IL-21 transcription, this might also be of functional relevance in humans.

Different contribution of glucocorticoids in the basolateral amygdala to the formation and expression of opiate withdrawal-associated memories

Drug-withdrawal aversive memories generate a motivational state leading to compulsive drug taking, with plasticity changes in the basolateral amygdala (BLA) being essential in aversive motivational learning. The conditioned-place aversion (CPA) paradigm allows for measuring the negative affective component of drug withdrawal. First, CPA triggers association between negative affective consequences of withdrawal with context (memory consolidation). Afterwards, when the animals are re-exposed to the paired environment, they avoid it due to the association between the context and aversive memories (memory retrieval). We examined the influence of glucocorticoids (GCs) for a morphine-withdrawal CPA paradigm, along with plasticity changes in the BLA, in sham-operated and adrenalectomized (ADX) animals. We demonstrated that sham+morphine animals robustly displayed CPA, whereas ADX-dependent animals lacked the affective-like signs of opiate withdrawal but displayed increased somatic signs of withdrawal. Glucocorticoid receptor (GR) actions promote memory consolidation but highly depend on increases in GC levels. Interestingly, we observed that GCs were only increased in sham-dependent rodents during aversive-withdrawal memory consolidation, and that GR expression correlated with phosphorylated cAMP response element binding (pCREB) protein, early growth response 1 (Egr-1) and activity-regulated cytoskeletal-associated (Arc) mRNA induction in this experimental group. In contrast, ADX-animals displayed reduced (pCREB). GCs are also known to impair memory retrieval. Accordingly, we showed that GCs levels remained at basal levels in all experimental groups following memory retrieval, and consequently GRs no longer acted as transcriptional regulators. Importantly, memory retrieval elicited increased pCREB levels in sham+morphine animals (not in ADX+morphine group), which were directly correlated with enhanced Arc mRNA/protein expression mainly in glutamatergic neurons. In conclusion, context-withdrawal associations are accompanied plasticity changes in the BLA, which are, in part, regulated by GR signaling. Moreover, dysregulation of CREB signaling, in part through Arc expression, may enhance reconsolidation, resulting in the maintenance of excessive aversive states. These findings might have important implications for drug-seeking behavior.

The cAMP response element modulator (CREM) regulates TH2 mediated inflammation

A characteristic feature of allergic diseases is the appearance of a subset of CD4⁺ cells known as T_H2 cells, which is controlled by transcriptional and epigenetic mechanisms. We aimed to analyze the role of CREM, a known transcriptional activator of T cells, with regard to T_H2 responses and allergic diseases in men and mice. Here we demonstrate that T cells of asthmatic children and PBMCs of adults with atopy express lower mRNA levels of the transcription factor CREM compared to cells from healthy controls. CREM deficiency in murine T cells results in enhanced T_H2 effector cytokines in vitro and in vivo and CREM^−/− mice demonstrate stronger airway hyperresponsiveness in an OVA-induced asthma model. Mechanistically, both direct CREM binding to the IL-4 and IL-13 promoter as well as a decreased IL-2 dependent STAT5 activation suppress the T_H2 response. Accordingly, mice selectively overexpressing CREMα in T cells display decreased T_H2 type cytokines in vivo and in vitro, and are protected in an asthma model. Thus, we provide evidence that CREM is a negative regulator of the T_H2 response and determines the outcome of allergic asthma.

Involvement of p38MAPK-ATF2 signaling pathway in alternariol induced DNA polymerase β expression

Base excision repair (BER) systems are important for maintaining the integrity of genomes in mammalian cells. Aberrant DNA bases or broken single strands can be repaired by BER. Consequently, DNA lesions, which may be caused by cancer and aging, have a close association with BER procedure. DNA polymerase β (polβ) is a critical BER enzyme that can excise 5'-sugar phosphate prior to adding a nucleotide in the gap by its function as a DNA polymerase in the BER process. However, DNA polβ is an error-prone DNA polymerase, and overexpressing polβ increases the cellular spontaneous mutation rate. DNA polβ overexpression has been identified in various human tumors, which implies that DNA polβ overexpression has a close association with tumorigenesis. The present study showed that alternariol (AOH), a secondary product of a fungus that is found in grains and fruits, could cause DNA damage to NIH3T3 cells in a single cell gel electrophoresis, and that 2, 10 and 20 µM AOH induced DNA polβ overexpression in a dose-dependent manner. In the process, the level of phosphorylation of mitogen-activated protein kinase 14 (p38) mitogen-activated protein kinase (MAPK) and activating transcription factor 2 (ATF2) was increased. In addition, SB203580, a p38MAPK inhibitor, resulted in decreased DNA polβ expression. Small hairpin RNA-p38MAPK had the same effect; notably, DNA polβ expression was downregulated in p38MAPK knockdown cells. These data suggest that the p38MAPK-ATF2 signaling pathway may be involved in DNA polβ expression induced by AOH.

Identification and Functional Characterization of Cis-Regulatory Elements Controlling Expression of the Porcine ADRB2 Gene

The beta-2 adrenergic receptor (beta-2 AR) modulates metabolic processes in skeletal muscle, liver, and adipose tissue in response to catecholamine stimulation. We showed previously that expression of the porcine beta-2 AR gene (ADRB2) is affected by cis-regulatory polymorphisms. These are most likely responsible for the association of ADRB2 with economically relevant muscle-related traits in pigs. The present study focused on characterization of promoter elements involved in basal transcriptional regulation of the porcine ADRB2 in different cell types to aid identification of its cis-regulatory polymorphisms. Based on in silico analysis, luciferase reporter gene assays and gel shift assays were performed using COS-7, HepG2, C2C12, and 3T3-L1 cells. Deletion mapping of the 5´ flanking region (-1324 to +33) of ADRB2 revealed the region between -307 and -269 to be the minimal promoter, including regulatory elements essential for the basal transcriptional activity in all four tested cell types. Directly upstream (-400 to -323) we identified an important enhancer element required for maximal promoter activity. In silico analysis and gel shift assays revealed that this GC-rich element harbors two evolutionarily conserved binding sites of Sp1, a constitutive transcriptional activator. Significant transcriptional activation of the porcine ADRB2 promoter was demonstrated by overexpression of Sp1. Our results demonstrate, for the first time, an important role of Sp1 and of the responsive enhancer element in the regulation of ADRB2 expression. Polymorphisms located in this domain of the porcine ADRB2 promoter represent candidate causal cis-regulatory variants.

Interleukin-2 treatment reverses effects of cAMP-responsive element modulator α-over-expressing T cells in autoimmune-prone mice

Systemic autoimmune diseases, such as systemic lupus erythematosus (SLE), are often characterized by a failure of self-tolerance and result in an uncontrolled activation of B cells and effector T cells. Interleukin (IL)-2 critically maintains homeostasis of regulatory T cells (T(reg)) and effector T cells in the periphery. Previously, we identified the cAMP-responsive element modulator α (CREMα) as a major factor responsible for decreased IL-2 production in T cells from SLE patients. Additionally, using a transgenic mouse that specifically over-expresses CREMα in T cells (CD2CREMαtg), we provided in-vivo evidence that CREMα indeed suppresses IL-2 production. To analyse the effects of CREMα in an autoimmune prone mouse model we introduced a Fas mutation in the CD2CREMαtg mice (FVB/Fas(-/-) CD2CREMαtg). Overexpression of CREMα strongly accelerated the lymphadenopathy and splenomegaly in the FVB/Fas(-/-) mice. This was accompanied by a massive expansion of double-negative (DN) T cells, enhanced numbers of interferon (IFN)-γ-producing T cells and reduced percentages of T(regs). Treatment of FVB/Fas(-/-) CD2CREMαtg mice with IL-2 restored the percentage of T(regs) and reversed increased IFN-γ production, but did not affect the number of DNTs. Our data indicate that CREMα contributes to the failure of tolerance in SLE by favouring effector T cells and decreasing regulatory T cells, partially mediated by repression of IL-2 in vivo.

Promoter analysis of the gene encoding GDNF in murine Sertoli cells

GDNF is a Sertoli-cell-derived factor that controls the balance between self-renewal and differentiation of the spermatogonial stem cells. Although research in recent years has concentrated on the impact of GDNF on target germ cells rather little attention has been paid to the molecular control of GDNF expression in Sertoli cells. Here, we aimed to characterize the promoter region of the mouse gdnf gene active in Sertoli cells. We identified the transcriptional start sites and analyzed the promoter activity of the 5'-flanking regions. By in-silico analysis of evolutionarily conserved DNA sequences we identified several putative transcription factor-binding regions. Deletion analysis showed the involvement of the three CRE sites for basal and cAMP-induced expression of gdnf in murine Sertoli cells. These results provide the basis for future studies to analyze how hormonal or paracrine signals modulate the transcriptional activity of gdnf in Sertoli cells.

Decompensation of β-cells in diabetes: when pancreatic β-cells are on ICE(R)

Insulin production and secretion are temporally regulated. Keeping insulin secretion at rest after a rise of glucose prevents exhaustion and ultimately failure of β-cells. Among the mechanisms that reduce β-cell activity is the inducible cAMP early repressor (ICER). ICER is an immediate early gene, which is rapidly induced by the cyclic AMP (cAMP) signaling cascade. The seminal function of ICER is to negatively regulate the production and secretion of insulin by repressing the genes expression. This is part of adaptive response required for proper β-cells function in response to environmental factors. Inappropriate induction of ICER accounts for pancreatic β-cells dysfunction and ultimately death elicited by chronic hyperglycemia, fatty acids, and oxidized LDL. This review underlines the importance of balancing the negative regulation achieved by ICER for preserving β-cell function and survival in diabetes.

The α and Δ isoforms of CREB1 are required to maintain normal pulmonary vascular resistance

Chronic hypoxia causes pulmonary hypertension associated with structural alterations in pulmonary vessels and sustained vasoconstriction. The transcriptional mechanisms responsible for these distinctive changes are unclear. We have previously reported that CREB1 is activated in the lung in response to alveolar hypoxia but not in other organs. To directly investigate the role of α and Δ isoforms of CREB1 in the regulation of pulmonary vascular resistance we examined the responses of mice in which these isoforms of CREB1 had been inactivated by gene mutation, leaving only the β isoform intact (CREB(αΔ) mice). Here we report that expression of CREB regulated genes was altered in the lungs of CREB(αΔ) mice. CREB(αΔ) mice had greater pulmonary vascular resistance than wild types, both basally in normoxia and following exposure to hypoxic conditions for three weeks. There was no difference in rho kinase mediated vasoconstriction between CREB(αΔ) and wild type mice. Stereological analysis of pulmonary vascular structure showed characteristic wall thickening and lumen reduction in hypoxic wild-type mice, with similar changes observed in CREB(αΔ). CREB(αΔ) mice had larger lungs with reduced epithelial surface density suggesting increased pulmonary compliance. These findings show that α and Δ isoforms of CREB1 regulate homeostatic gene expression in the lung and that normal activity of these isoforms is essential to maintain low pulmonary vascular resistance in both normoxic and hypoxic conditions and to maintain the normal alveolar structure. Interventions that enhance the actions of α and Δ isoforms of CREB1 warrant further investigation in hypoxic lung diseases.

Cyclic AMP synergizes with butyrate in promoting β-defensin 9 expression in chickens

Host defense peptides (HDP) have both microbicidal and immunomodulatory properties. Specific induction of endogenous HDP synthesis has emerged as a novel approach to antimicrobial therapy. Cyclic adenosine monophosphate (cAMP) and butyrate have been implicated in HDP induction in humans. However, the role of cAMP signaling and the possible interactions between cAMP and butyrate in regulating HDP expression in other species remain unknown. Here we report that activation of cAMP signaling induces HDP gene expression in chickens as exemplified by β-defensin 9 (AvBD9). We further showed that, albeit being weak inducers, cAMP agonists synergize strongly with butyrate or butyrate analogs in AvBD9 induction in macrophages and primary jejunal explants. Additionally, oral supplementation of forskolin, an adenylyl cyclase agonist in the form of a Coleus forskohlii extract, was found to induce AvBD9 expression in the crop of chickens. Furthermore, feeding with both forskolin and butyrate showed an obvious synergy in triggering AvBD9 expression in the crop and jejunum of chickens. Surprisingly, inhibition of the MEK-ERK mitogen-activated protein kinase (MAPK) pathway augmented the butyrate-FSK synergy, whereas blocking JNK or p38 MAPK pathway significantly diminished AvBD9 induction in chicken macrophages and jejunal explants in response to butyrate and FSK individually or in combination. Collectively, these results suggest the potential for concomitant use of butyrate and cAMP signaling activators in enhancing HDP expression, innate immunity, and disease resistance in both animals and humans.

Overexpression of CREMα in T cells aggravates lipopolysaccharide-induced acute lung injury

Transcription factor cAMP response element modulator (CREM)α contributes to various cellular and molecular abnormalities in T cells, including increased IL-17 and decreased IL-2 expression. For development of acute lung injury (ALI), the invasion and regulation of immune cells are highly important, but the role of T cells remains unclear. In this study, we show that CREMα is upregulated in LPS-induced ALI. During the early phase of ALI (day 1), T cell-specific CREMα overexpression enhances the numbers of T cells and expression of TNF-α in bronchoalveolar lavage fluid and deteriorates lung functions. On day 3 of ALI, CREMα transgenic mice present a stronger inflammatory response with higher levels of TNF-α, IL-6, and IL-17 correlating with increased numbers of T cells and neutrophils in bronchoalveolar lavage fluid, whereas expression of Foxp3 and IL-2 and numbers of regulatory T cells are decreased. These changes result in restricted lung function in CREMα transgenic mice. Finally, an adoptive transfer of CREM(-/-) CD4(+) T cells, but not of wild-type T cells into RAG-1(-/-) mice results in ameliorated disease levels. Thus, levels of CREM in T cells determine the outcome of ALI, and CREMα transgenic animals represent a model in which proinflammatory T cells aggravate ALI in different phases of the disease. Given the fact that patients with autoimmune diseases like systemic lupus erythematosus show higher levels of CREMα and an increased susceptibility toward infectious complications, our finding is of potential clinical significance and may enable new therapeutic strategies.

Characterization of the mouse promoter region of the acyl-CoA synthetase 4 gene: role of Sp1 and CREB

Acyl-CoA synthetase 4 (Acsl4) is involved in several cellular functions including steroidogenesis, synaptic development and cancer metastasis. Although the expression of Acsl4 seems to be regulated by tissue- and cell-specific factors as well as pituitary hormones and growth factors, the transcriptional mechanisms involved remain unknown. We demonstrated hCG and cAMP regulation of Acsl4 mRNA in mouse steroidogenic MA-10 Leydig cells. We characterized the transcription initiation site and promoter of the Acsl4 mouse gene and identified three alternative splice variants present in MA-10 cells. Sequence analysis of a 1.5-kb fragment of the Acsl4 promoter revealed the absence of a TATA box and the presence of many putative binding sites for transcription factors including Sp1 and CREB. Functional characterization revealed that the specificity protein/Krüppel-like factor Sp1 binding site in the proximal promoter is involved in basal activity and that the cAMP response element-binding site is involved in cAMP stimulation of Acsl4 transcription.

Increasing CRTC1 function in the dentate gyrus during memory formation or reactivation increases memory strength without compromising memory quality

Memory stabilization following encoding (synaptic consolidation) or memory reactivation (reconsolidation) requires gene expression and protein synthesis (Dudai and Eisenberg, 2004; Tronson and Taylor, 2007; Nader and Einarsson, 2010; Alberini, 2011). Although consolidation and reconsolidation may be mediated by distinct molecular mechanisms (Lee et al., 2004), disrupting the function of the transcription factor CREB impairs both processes (Kida et al., 2002; Mamiya et al., 2009). Phosphorylation of CREB at Ser133 recruits CREB binding protein (CBP)/p300 coactivators to activate transcription (Chrivia et al., 1993; Parker et al., 1996). In addition to this well known mechanism, CREB regulated transcription coactivators (CRTCs), previously called transducers of regulated CREB (TORC) activity, stimulate CREB-mediated transcription, even in the absence of CREB phosphorylation. Recently, CRTC1 has been shown to undergo activity-dependent trafficking from synapses and dendrites to the nucleus in excitatory hippocampal neurons (Ch'ng et al., 2012). Despite being a powerful and specific coactivator of CREB, the role of CRTC in memory is virtually unexplored. To examine the effects of increasing CRTC levels, we used viral vectors to locally and acutely increase CRTC1 in the dorsal hippocampus dentate gyrus region of mice before training or memory reactivation in context fear conditioning. Overexpressing CRTC1 enhanced both memory consolidation and reconsolidation; CRTC1-mediated memory facilitation was context specific (did not generalize to nontrained context) and long lasting (observed after virally expressed CRTC1 dissipated). CREB overexpression produced strikingly similar effects. Therefore, increasing CRTC1 or CREB function is sufficient to enhance the strength of new, as well as established reactivated, memories without compromising memory quality.

A review of the molecular aspects of melatonin's anti-inflammatory actions: recent insights and new perspectives

Melatonin is a highly evolutionary conserved endogenous molecule that is mainly produced by the pineal gland, but also by other nonendocrine organs, of most mammals including man. In the recent years, a variety of anti-inflammatory and antioxidant effects have been observed when melatonin is applied exogenously under both in vivo and in vitro conditions. A number of studies suggest that this indole may exert its anti-inflammatory effects through the regulation of different molecular pathways. It has been documented that melatonin inhibits the expression of the isoforms of inducible nitric oxide synthase and cyclooxygenase and limits the production of excessive amounts of nitric oxide, prostanoids, and leukotrienes, as well as other mediators of the inflammatory process such as cytokines, chemokines, and adhesion molecules. Melatonin's anti-inflammatory effects are related to the modulation of a number of transcription factors such as nuclear factor kappa B, hypoxia-inducible factor, nuclear factor erythroid 2-related factor 2, and others. Melatonin's effects on the DNA-binding capacity of transcription factors may be regulated through the inhibition of protein kinases involved in signal transduction, such as mitogen-activated protein kinases. This review summarizes recent research data focusing on the modulation of the expression of different inflammatory mediators by melatonin and the effects on cell signaling pathways responsible for the indole's anti-inflammatory activity. Although there are a numerous published reports that have analyzed melatonin's anti-inflammatory properties, further studies are necessary to elucidate its complex regulatory mechanisms in different cellular types and tissues.

Expression of cell growth negative regulators MEG3 and GADD45γ is lost in most sporadic human pituitary adenomas

We aimed at the evaluation of MEG3 and GADD45γ expression in sporadic functioning and clinically non-functioning human pituitary adenomas, morphologically characterized by immunohistochemistry analysis and their association with clinical features. Thirty eight patients who had undergone hypophysectomy at São José Hospital of Irmandade Santa Casa de Misericórdia in Porto Alegre, Brazil, were included in this study. We evaluated tumor-type specific MEG3 and GADD45γ expression by qRT-PCR in the pituitary adenomas, and its association with clinical features, as age, gender and tumor size, obtained from medical records. The patients consisted of 21 males and 17 females and the mean age was 47 ± 14 (mean ± SD), ranging from 18 to 73 years-old. Of these 14 were clinically non-functioning, 10 GH-secreting, 9 PRL-secreting, and 5 ACTH-secreting pituitary adenomas. All samples were macroadenomas, except four ACTH-secreting tumors, which were microadenomas. In summary, MEG3 and GADD45γ expression was significantly lost in most clinically non-functioning adenomas (78 and 92%, respectively). Other assessed pituitary tumor phenotypes expressed both genes at significantly different levels, and, in some cases, with overexpression. There was no significant association between gene expression and the analyzed clinical features. Our results confirm the previous report, which indicated that MEG3 and GADD45γ expression is lost in the majority of human pituitary tumors, mainly in clinically-nonfunctioning adenomas. Functioning tumors had differences of relative expression levels. The two groups of tumors are probably genetically different and may have a different natural history.

Clenbuterol upregulates histone demethylase JHDM2a via the β2-adrenoceptor/cAMP/PKA/p-CREB signaling pathway

BACKGROUND

β(2)-Adrenergic receptor (β(2)-AR) signaling activated by the agonist clenbuterol is important in the metabolism of muscle and adipose cells. Additionally, the significant role of histone demethylase JHDM2a in regulating metabolic gene expression was also recently demonstrated in Jhdm2a(-/-) mice. To elucidate the molecular mechanism involved in clenbuterol-induced adipocyte reduction from an epigenetic perspective, this study focused on cAMP-responsive element binding protein (CREB) to determine whether JHDM2a is regulated by the β(2)-AR/cAMP/protein kinase A (PKA) signaling pathway.

RESULTS

In porcine tissues treated with clenbuterol, JHDM2a expression was upregulated, and in porcine cells, expression of exogenous CREB led to increased JHDM2a expression. In addition, changes in JHDM2a expression were coincident with variations in the phosphorylation of CREB and p-CREB/CBP interaction in porcine and human cells treated with drugs known to modify the β(2)-AR/cAMP/PKA pathway. Finally, binding assays demonstrated that CREB regulated JHDM2a by binding directly to the CRE site nearest to the transcription start site.

CONCLUSION

Our results reveal that clenbuterol activates the β(2)-AR signaling pathway upstream of JHDM2a and that CREB acts as an intermediate link regulated by cAMP-PKA to induce activity of the JHDM2a promoter. These findings suggest that clenbuterol decreases adipose cell size and increases muscle fiber size in porcine tissues by virtue of JHDM2a-mediated demethylation, which regulates downstream metabolic and related genes.

Research resource: A genome-wide study identifies potential new target genes for POU1F1

The pituitary transcription factor POU1F1 is required for the differentiation of lactotrope, thyrotrope, and somatotrope cells. Its expression is maintained in the adult and is crucial for the expression of prolactin, GH, and TSHβ-subunit. Different studies indicated that POU1F1 could also have other functions in these cells. The identification of new targets of this factor could be useful to obtain a better understanding of these functions. To address this question we combined data obtained from expression microarrays and from chromatin immunoprecipitation (ChIP)-chips. Gene expression microarray assays were used to detect genes that have their expression modified in somatolactotrope GH4C1 cells by the expression of a dominant-negative form of POU1F1, POU1F1(R271W), and led to the identification of 1346 such genes. ChIP-chip experiments were performed from mouse pituitaries and identified 1671 POU1F1-binding sites in gene-promoter regions. Intersecting the gene expression and the ChIP-chip data yielded 121 potential new direct targets. The initial set of 1346 genes identified using the microarrays, as well as the 121 potential new direct targets, were analyzed with DAVID bioinformatics resource for gene ontology term enrichment and cluster. This analysis revealed enrichment in different terms related to protein synthesis and transport, to apoptosis, and to cell division. The present study represents an integrative genome-wide approach to identify new target genes of POU1F1 and downstream networks controlled by this factor.

Role of CREM in systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is a complex autoimmune disease. Immune complex, autoantibodies and autoreactive lymphocytes are involved in manifestations of SLE. Recently, investigations have indicated that expression of the transcription factor cAMP responsive element modulator (CREM) is abnormal in T cells and might play an important role in the pathogenesis of SLE. CREM has much influence on the promoters, such as IL-2, c-fos, TCR ζ, and SYK. Moreover, activity of CREM itself has been demonstrated, particularly with an auto-regulatory feedback mechanism. Therefore, we will discuss the association of CREM and SLE based on current knowledge to unravel the mechanism of CREM performance.

Distinctive roles for amygdalar CREB in reconsolidation and extinction of fear memory

Cyclic AMP response element binding protein (CREB) plays a critical role in fear memory formation. Here we determined the role of CREB selectively within the amygdala in reconsolidation and extinction of auditory fear. Viral overexpression of the inducible cAMP early repressor (ICER) or the dominant-negative mCREB, specifically within the lateral amygdala disrupted reconsolidation of auditory fear memories. In contrast, manipulations of CREB in the amygdala did not modify extinction of fear. These findings suggest that the role of CREB in modulation of memory after retrieval is dynamic and that CREB activity in the basolateral amygdala is involved in fear memory reconsolidation.

MicroRNA-34c enhances murine male germ cell apoptosis through targeting ATF1

Background

MicroRNAs (miRNAs) play vital regulatory roles in many cellular processes. The expression of miRNA (miR)-34c is highly enriched in adult mouse testis, but its roles and underlying mechanisms of action are not well understood.

Methodology/Principal Findings

In the present study, we show that miR-34c is detected in mouse pachytene spermatocytes and continues to be highly expressed in spermatids. To explore the specific functions of miR-34c, we have established an in vivo model by transfecting miR-34c inhibitors into primary spermatocytes to study the loss-of-function of miR-34c. The results show that silencing of miR-34c significantly increases the Bcl-2/Bax ratio and prevents germ cell from apoptosis induced by deprivation of testosterone. Moreover, ectopic expression of the miR-34c in GC-2 cell trigger the cell apoptosis with a decreased Bcl-2/Bax ratio and miR-34c inhibition lead to a low spontaneous apoptotic ratio and an increased Bcl-2/Bax ratio. Furthermore, ectopic expression of miR-34c reduces ATF1 protein expression without affecting ATF1 mRNA level via directly binding to ATF1's 3′UTR, indicating that ATF1 is one of miR-34c's target genes. Meanwhile, the knockdown of ATF1 significantly decreases the Bcl-2/Bax ratio and triggers GC-2 cell apoptosis. Inhibition of miR-34c does not decrease the GC-2 cell apoptosis ratio in ATF1 knockdown cells.

Conclusions/Significance

Our study shows for the first time that miR-34c functions, at least partially, by targeting the ATF1 gene in germ cell apoptosis, providing a novel mechanism with involvement of miRNA in the regulation of germ cell apoptosis.

Methamphetamine causes differential alterations in gene expression and patterns of histone acetylation/hypoacetylation in the rat nucleus accumbens

Methamphetamine (METH) addiction is associated with several neuropsychiatric symptoms. Little is known about the effects of METH on gene expression and epigenetic modifications in the rat nucleus accumbens (NAC). Our study investigated the effects of a non-toxic METH injection (20 mg/kg) on gene expression, histone acetylation, and the expression of the histone acetyltransferase (HAT), ATF2, and of the histone deacetylases (HDACs), HDAC1 and HDAC2, in that structure. Microarray analyses done at 1, 8, 16 and 24 hrs after the METH injection identified METH-induced changes in the expression of genes previously implicated in the acute and longterm effects of psychostimulants, including immediate early genes and corticotropin-releasing factor (Crf). In contrast, the METH injection caused time-dependent decreases in the expression of other genes including Npas4 and cholecystokinin (Cck). Pathway analyses showed that genes with altered expression participated in behavioral performance, cell-to-cell signaling, and regulation of gene expression. PCR analyses confirmed the changes in the expression of c-fos, fosB, Crf, Cck, and Npas4 transcripts. To determine if the METH injection caused post-translational changes in histone markers, we used western blot analyses and identified METH-mediated decreases in histone H3 acetylated at lysine 9 (H3K9ac) and lysine 18 (H3K18ac) in nuclear sub-fractions. In contrast, the METH injection caused time-dependent increases in acetylated H4K5 and H4K8. The changes in histone acetylation were accompanied by decreased expression of HDAC1 but increased expression of HDAC2 protein levels. The histone acetyltransferase, ATF2, showed significant METH-induced increased in protein expression. These results suggest that METH-induced alterations in global gene expression seen in rat NAC might be related, in part, to METH-induced changes in histone acetylation secondary to changes in HAT and HDAC expression. The causal role that HATs and HDACs might play in METH-induced gene expression needs to be investigated further.

Transcriptional regulation of N-acetylglutamate synthase

The urea cycle converts toxic ammonia to urea within the liver of mammals. At least 6 enzymes are required for ureagenesis, which correlates with dietary protein intake. The transcription of urea cycle genes is, at least in part, regulated by glucocorticoid and glucagon hormone signaling pathways. N-acetylglutamate synthase (NAGS) produces a unique cofactor, N-acetylglutamate (NAG), that is essential for the catalytic function of the first and rate-limiting enzyme of ureagenesis, carbamyl phosphate synthetase 1 (CPS1). However, despite the important role of NAGS in ammonia removal, little is known about the mechanisms of its regulation. We identified two regions of high conservation upstream of the translation start of the NAGS gene. Reporter assays confirmed that these regions represent promoter and enhancer and that the enhancer is tissue specific. Within the promoter, we identified multiple transcription start sites that differed between liver and small intestine. Several transcription factor binding motifs were conserved within the promoter and enhancer regions while a TATA-box motif was absent. DNA-protein pull-down assays and chromatin immunoprecipitation confirmed binding of Sp1 and CREB, but not C/EBP in the promoter and HNF-1 and NF-Y, but not SMAD3 or AP-2 in the enhancer. The functional importance of these motifs was demonstrated by decreased transcription of reporter constructs following mutagenesis of each motif. The presented data strongly suggest that Sp1, CREB, HNF-1, and NF-Y, that are known to be responsive to hormones and diet, regulate NAGS transcription. This provides molecular mechanism of regulation of ureagenesis in response to hormonal and dietary changes.

Novel insights into the downstream pathways and targets controlled by transcription factors CREM in the testis

The essential role of the Crem gene in normal sperm development is widely accepted and is confirmed by azoospermia in male mice lacking the Crem gene. The exact number of genes affected by Crem absence is not known, however a large difference has been observed recently between the estimated number of differentially expressed genes found in Crem knock-out (KO) mice compared to the number of gene loci bound by CREM. We therefore re-examined global gene expression in male mice lacking the Crem gene using whole genome transcriptome analysis with Affymetrix microarrays and compared the lists of differentially expressed genes from Crem−/− mice to a dataset of genes where binding of CREM was determined by Chip-seq. We determined the global effect of CREM on spermatogenesis as well as distinguished between primary and secondary effects of the CREM absence. We demonstrated that the absence of Crem deregulates over 4700 genes in KO testis. Among them are 101 genes associated with spermatogenesis 41 of which are bound by CREM and are deregulated in Crem KO testis. Absence of several of these genes in mouse models has proven their importance for normal spermatogenesis and male fertility. Our study showed that the absence of Crem plays a more important role on different aspects of spermatogenesis as estimated previously, with its impact ranging from apoptosis induction to deregulation of major circadian clock genes, steroidogenesis and the cell-cell junction dynamics. Several new genes important for normal spermatogenesis and fertility are down-regulated in KO testis and are therefore possible novel targets of CREM.

cAMP-responsive element modulator (CREM)α protein induces interleukin 17A expression and mediates epigenetic alterations at the interleukin-17A gene locus in patients with systemic lupus erythematosus

IL-17A is a proinflammatory cytokine that is produced by specialized T helper cells and contributes to the development of several autoimmune diseases such as systemic lupus erythematosus (SLE). Transcription factor cAMP-responsive element modulator (CREM)α displays increased expression levels in T cells from SLE patients and has been described to account for aberrant T cell function in SLE pathogenesis. In this report, we provide evidence that CREMα physically binds to a cAMP-responsive element, CRE (-111/-104), within the proximal human IL17A promoter and increases its activity. Chromatin immunoprecipitation assays reveal that activated naïve CD4(+) T cells as well as T cells from SLE patients display increased CREMα binding to this site compared with T cells from healthy controls. The histone H3 modification pattern at the CRE site (-111/-104) and neighboring conserved noncoding sequences within the human IL17A gene locus suggests an accessible chromatin structure (H3K27 hypomethylation/H3K18 hyperacetylation) in activated naïve CD4(+) T cells and SLE T cells. H3K27 hypomethylation is accompanied by decreased cytosine phosphate guanosine (CpG)-DNA methylation in these regions in SLE T cells. Decreased recruitment of histone deacetylase (HDAC)1 and DNA methyltransferase (DNMT)3a to the CRE site (-111/-104) probably accounts for the observed epigenetic alterations. Reporter studies confirmed that DNA methylation of the IL17A promoter indeed abrogates its inducibility. Our findings demonstrate an extended role for CREMα in the immunopathogenesis of SLE because it contributes to increased expression of IL-17A.

Pituitary adenylate cyclase-activating peptide induces long-lasting neuroprotection through the induction of activity-dependent signaling via the cyclic AMP response element-binding protein-regulated transcription co-activator 1

Pituitary adenylate cyclase-activating peptide (PACAP) is a neuroprotective peptide which exerts its effects mainly through the cAMP-protein kinase A (PKA) pathway. Here, we show that in cortical neurons, PACAP-induced PKA signaling exerts a major part of its neuroprotective effects indirectly, by triggering action potential (AP) firing. Treatment of cortical neurons with PACAP induces a rapid and sustained PKA-dependent increase in AP firing and associated intracellular Ca²⁺ transients, which are essential for the anti-apoptotic actions of PACAP. Transient exposure to PACAP induces long-lasting neuroprotection in the face of apoptotic insults which is reliant on AP firing and the activation of cAMP response element (CRE) binding protein (CREB)-mediated gene expression. Although direct, activity-independent PKA signaling is sufficient to trigger phosphorylation on CREB’s activating serine-133 site, this is insufficient for activation of CREB-mediated gene expression. Full activation is dependent on CREB-regulated transcription co-activator 1 (CRTC1), whose PACAP-induced nuclear import is dependent on firing activity-dependent calcineurin signaling. Over-expression of CRTC1 is sufficient to rescue PACAP-induced CRE-mediated gene expression in the face of activity-blockade, while dominant negative CRTC1 interferes with PACAP-induced, CREB-mediated neuroprotection. Thus, the enhancement of AP firing may play a significant role in the neuroprotective actions of PACAP and other adenylate cyclase-coupled ligands.

CRTC3 links catecholamine signalling to energy balance

The adipose-derived hormone leptin maintains energy balance in part through central nervous system-mediated increases in sympathetic outflow that enhance fat burning. Triggering of β-adrenergic receptors in adipocytes stimulates energy expenditure by cyclic AMP (cAMP)-dependent increases in lipolysis and fatty-acid oxidation. Although the mechanism is unclear, catecholamine signalling is thought to be disrupted in obesity, leading to the development of insulin resistance. Here we show that the cAMP response element binding (CREB) coactivator Crtc3 promotes obesity by attenuating β-adrenergic receptor signalling in adipose tissue. Crtc3 was activated in response to catecholamine signals, when it reduced adenyl cyclase activity by upregulating the expression of Rgs2, a GTPase-activating protein that also inhibits adenyl cyclase activity. As a common human CRTC3 variant with increased transcriptional activity is associated with adiposity in two distinct Mexican-American cohorts, these results suggest that adipocyte CRTC3 may play a role in the development of obesity in humans.