Transcription factor CREB3L1 mediates cAMP and glucocorticoid regulation of arginine vasopressin gene transcription in the rat hypothalamus

Dimerization of hub protein DYNLL1 and bZIP transcription factor CREB3L1 enhances transcriptional activation of CREB3L1 target genes like arginine vasopressin

bZIP transcription factors can function as homodimers or heterodimers through interactions with their disordered coiled-coil domain. Such dimer assemblies are known to influence DNA-binding specificity and/or the recruitment of binding partners, which can cause a functional switch of a transcription factor from being an activator to a repressor. We recently identified the genomic targets of a bZIP transcription factor called CREB3L1 in rat hypothalamic supraoptic nucleus by ChIP-seq. The objective of this study was to investigate the CREB3L1 protein-to-protein interactome of which little is known. For this approach, we created and screened a rat supraoptic nucleus yeast two-hybrid prey library with the bZIP region of rat CREB3L1 as the bait. Our yeast two-hybrid approach captured five putative CREB3L1 interacting prey proteins in the supraoptic nucleus. One interactor was selected by bioinformatic analyses for more detailed investigation by co-immunoprecipitation, immunofluorescent cellular localisation, and reporter assays in vitro. Here we identify dimerisation hub protein Dynein Light Chain LC8-Type 1 as a CREB3L1 interacting protein that in vitro enhances CREB3L1 activation of target genes.

Male rat hypothalamic extraretinal photoreceptor Opsin3 is sensitive to osmotic stimuli and light

The light-sensitive protein Opsin 3 (Opn3) is present throughout the mammalian brain; however, the role of Opn3 in this organ remains unknown. Since Opn3 encoded mRNA is modulated in the supraoptic and paraventricular nucleus of the hypothalamus in response to osmotic stimuli, we have explored by in situ hybridization the expression of Opn3 in these nuclei. We have demonstrated that Opn3 is present in the male rat magnocellular neurones expressing either the arginine vasopressin or oxytocin neuropeptides and that Opn3 increases in both neuronal types in response to osmotic stimuli, suggesting that Opn3 functions in both cell types and that it might be involved in regulating water balance. Using rat hypothalamic organotypic cultures, we have demonstrated that the hypothalamus is sensitive to light and that the observed light sensitivity is mediated, at least in part, by Opn3. The data suggests that hypothalamic Opn3 can mediate a light-sensitive role to regulate circadian homeostatic processes.

The Regulatory Network of CREB3L1 and Its Roles in Physiological and Pathological Conditions

CREB3 subfamily belongs to the bZIP transcription factor family and comprises five members. Normally they are located on the endoplasmic reticulum (ER) membranes and proteolytically activated through RIP (regulated intramembrane proteolysis) on Golgi apparatus to liberate the N-terminus to serve as transcription factors. CREB3L1 acting as one of them transcriptionally regulates the expressions of target genes and exhibits distinct functions from the other members of CREB3 family in eukaryotes. Physiologically, CREB3L1 involves in the regulation of bone morphogenesis, neurogenesis, neuroendocrine, secretory cell differentiation, and angiogenesis. Pathologically, CREB3L1 implicates in the modulation of osteogenesis imperfecta, low grade fibro myxoid sarcoma (LGFMS), sclerosing epithelioid fibrosarcoma (SEF), glioma, breast cancer, thyroid cancer, and tissue fibrosis. This review summarizes the upstream and downstream regulatory network of CREB3L1 and thoroughly presents our current understanding of CREB3L1 research progress in both physiological and pathological conditions with special focus on the novel findings of CREB3L1 in cancers.

Epigenomic response to albuterol treatment in asthma-relevant airway epithelial cells

BACKGROUND

Albuterol is the first-line asthma medication used in diverse populations. Although DNA methylation (DNAm) is an epigenetic mechanism involved in asthma and bronchodilator drug response (BDR), no study has assessed whether albuterol could induce changes in the airway epithelial methylome. We aimed to characterize albuterol-induced DNAm changes in airway epithelial cells, and assess potential functional consequences and the influence of genetic variation and asthma-related clinical variables.

RESULTS

We followed a discovery and validation study design to characterize albuterol-induced DNAm changes in paired airway epithelial cultures stimulated in vitro with albuterol. In the discovery phase, an epigenome-wide association study using paired nasal epithelial cultures from Puerto Rican children (n = 97) identified 22 CpGs genome-wide associated with repeated-use albuterol treatment (p < 9 × 10-8). Albuterol predominantly induced a hypomethylation effect on CpGs captured by the EPIC array across the genome (probability of hypomethylation: 76%, p value = 3.3 × 10-5). DNAm changes on the CpGs cg23032799 (CREB3L1), cg00483640 (MYLK4-LINC01600), and cg05673431 (KSR1) were validated in nasal epithelia from 10 independent donors (false discovery rate [FDR] < 0.05). The effect on the CpG cg23032799 (CREB3L1) was cross-tissue validated in bronchial epithelial cells at nominal level (p = 0.030). DNAm changes in these three CpGs were shown to be influenced by three independent genetic variants (FDR < 0.05). In silico analyses showed these polymorphisms regulated gene expression of nearby genes in lungs and/or fibroblasts including KSR1 and LINC01600 (6.30 × 10-14 ≤ p ≤ 6.60 × 10-5). Additionally, hypomethylation at the CpGs cg10290200 (FLNC) and cg05673431 (KSR1) was associated with increased gene expression of the genes where they are located (FDR < 0.05). Furthermore, while the epigenetic effect of albuterol was independent of the asthma status, severity, and use of medication, BDR was nominally associated with the effect on the CpG cg23032799 (CREB3L1) (p = 0.004). Gene-set enrichment analyses revealed that epigenomic modifications of albuterol could participate in asthma-relevant processes (e.g., IL-2, TNF-α, and NF-κB signaling pathways). Finally, nine differentially methylated regions were associated with albuterol treatment, including CREB3L1, MYLK4, and KSR1 (adjusted p value < 0.05).

CONCLUSIONS

This study revealed evidence of epigenetic modifications induced by albuterol in the mucociliary airway epithelium. The epigenomic response induced by albuterol might have potential clinical implications by affecting biological pathways relevant to asthma.

Osmoadaptive GLP-1R signalling in hypothalamic neurones inhibits antidiuretic hormone synthesis and release

OBJECTIVES

The excessive release of the antidiuretic hormone vasopressin is implicated in many diseases including cardiovascular disease, diabetes, obesity, and metabolic syndrome. Once thought to be elevated as a consequence of diseases, data now supports a more causative role. We have previously identified CREB3L1 as a transcription factor that co-ordinates vasopressin synthesis and release in the hypothalamus. The objective here was to identify mechanisms orchestrated by CREB3L1 that co-ordinate vasopressin release.

METHODS

We mined Creb3l1 knockdown SON RNA-seq data to identify downstream target genes. We proceeded to investigate the expression of these genes and associated pathways in the supraoptic nucleus of the hypothalamus in response to physiological and pharmacological stimulation. We used viruses to selectively knockdown gene expression in the supraoptic nucleus and assessed physiological and metabolic parameters. We adopted a phosphoproteomics strategy to investigate mechanisms that facilitate hormone release by the pituitary gland.

RESULTS

We discovered glucagon like peptide 1 receptor (Glp1r) as a downstream target gene and found increased expression in stimulated vasopressin neurones. Selective knockdown of supraoptic nucleus Glp1rs resulted in decreased food intake and body weight. Treatment with GLP-1R agonist liraglutide decreased vasopressin synthesis and release. Quantitative phosphoproteomics of the pituitary neurointermediate lobe revealed that liraglutide initiates hyperphosphorylation of presynapse active zone proteins that control vasopressin exocytosis.

CONCLUSION

In summary, we show that GLP-1R signalling inhibits the vasopressin system. Our data advises that hydration status may influence the pharmacodynamics of GLP-1R agonists so should be considered in current therapeutic strategies.

Association between glucocorticoid use and all-cause mortality in critically ill patients with heart failure: A cohort study based on the MIMIC-III database

Background: Heart failure (HF) is the terminal stage of various heart diseases. Conventional treatments have poor efficacy, and diuretic resistance can present. Previous studies have found that the use of glucocorticoids can enhance the diuretic effect of patients with heart failure and reduce heart failure symptoms. However, the relationship between glucocorticoid use and mortality in patients with heart failure in intensive care units is unclear. Objectives: The aim of this study was to determine the association between glucocorticoid use and all-cause mortality in critically ill patients with heart failure. Methods: The information on patients with heart failure in this study was extracted from the MIMIC-III (Medical Information Mart for Intensive Care-III) database. Patients in the glucocorticoid and non-glucocorticoid groups were matched using propensity scores. The Kaplan-Meier method was used to explore the difference in survival probability between the two groups. A Cox proportional-hazards regression model was used to analyze the hazard ratios (HRs) for the two patient groups. Subgroup analyses were performed with prespecified stratification variables to demonstrate the robustness of the results. Results: The study included 9,482 patients: 2,099 in the glucocorticoid group and 7,383 in the non-glucocorticoid group. There were 2,055 patients in each group after propensity-score matching. The results indicated that the non-glucocorticoid group was not significantly associated with reduced mortality in patients with heart failure during the 14-day follow-up period [HRs = .901, 95% confidence interval (CI) = .767-1.059]. During the follow-up periods of 15-30 and 15-90 days, the mortality risk was significantly lower in the non-glucocorticoid group than in the glucocorticoid group (HRs = .497 and 95% CI = .370-.668, and HRs = .400 and 95% CI = .310-.517, respectively). Subgroup analyses indicated no interaction among each stratification variable and glucocorticoid use. Conclusion: Glucocorticoid use was associated with an increased mortality risk in critically ill patients with heart failure.

Integrating network pharmacology and experimental verification to explore the mechanism of puerarin against oliguria in acute alcoholism

Purpose: This study was designed to evaluate the pharmacological mechanisms of puerarin against oliguria in acute alcoholism via network pharmacology analysis combined with experimental verification.

Methods: First, this study established an acute alcoholism rat model, compared the changes in urine volume in each group, and observed the therapeutic effect of puerarin by H&amp;E staining, biochemical, RT-qPCR, and immunohistochemical analyses. Second, puerarin-related targets were searched in TCMS, PubChem, CNKI, Wanfang, PubMed, and GeenMedical Academic databases. Also, potential disease targets were obtained from the GeneCards, MalaCards, and NCBI-gene databases and genes with puerarin target gene intersections were screened out. The interaction network for co-predicted targets was obtained using the STRING database, and the core targets were imported into Cytoscape for visualization using DAVID Bioinformatics Resources 6.8. The essential genes were subjected to the Kyoto Encyclopedia of Genes and Genomes (KEGG) and Gene Ontology (GO) pathway enrichment analyses to predict related biological processes and significant signaling pathways. Finally, molecular docking was used to examine the interaction of puerarin with key targets, and the core targets were validated further by RT-qPCR and Western blotting.

Results: Compared to the model group, the urine volume of the rats was significantly increased after puerarin treatment, and the levels of anti-diuretic hormone (ADH) and aquaporin 2 (AQP2) expression were decreased. Searching the intersection of puerarin and acute alcoholism targets yielded 214 potential targets, 837 biological processes, and 185 signaling pathways involved. The molecular docking results indicated a good affinity between puerarin and key targets (cyclic adenosine monophosphate (cAMP), protein kinase A (PKA), cAMP-response element-binding protein (CREB), and c-Fos). RT-qPCR and Western blotting further verified that puerarin could down-regulate the expression of cAMP/PKA/CREB/c-Fos.

Conclusion: This study identified the potential targets of puerarin against oliguria in rats with acute alcoholism using network pharmacology and animal experiments. The mechanism may be closely related to the cAMP signaling pathway.

Transcriptomic plasticity of the hypothalamic osmoregulatory control centre of the Arabian dromedary camel

Water conservation is vital for life in the desert. The dromedary camel (Camelus dromedarius) produces low volumes of highly concentrated urine, more so when water is scarce, to conserve body water. Two hormones, arginine vasopressin and oxytocin, both produced in the supraoptic nucleus, the core hypothalamic osmoregulatory control centre, are vital for this adaptive process, but the mechanisms that enable the camel supraoptic nucleus to cope with osmotic stress are not known. To investigate the central control of water homeostasis in the camel, we first build three dimensional models of the camel supraoptic nucleus based on the expression of the vasopressin and oxytocin mRNAs in order to facilitate sampling. We then compare the transcriptomes of the supraoptic nucleus under control and water deprived conditions and identified genes that change in expression due to hyperosmotic stress. By comparing camel and rat datasets, we have identified common elements of the water deprivation transcriptomic response network, as well as elements, such as extracellular matrix remodelling and upregulation of angiotensinogen expression, that appear to be unique to the dromedary camel and that may be essential adaptations necessary for life in the desert.

Transcription factor Creb3l1 maintains proteostasis in neuroendocrine cells

OBJECTIVES

Dynamic changes to neuropeptide hormone synthesis and secretion by hypothalamic neuroendocrine cells is essential to ensure metabolic homeostasis. The specialised molecular mechanisms that allow neuroendocrine cells to synthesise and secrete vast quantities of neuropeptides remain ill defined. The objective of this study was to identify novel genes and pathways controlled by transcription factor and endoplasmic reticulum stress sensor Creb3l1 which is robustly activated in hypothalamic magnocellular neurones in response to increased demand for protein synthesis.

METHODS

We adopted a multiomic strategy to investigate specific roles of Creb3l1 in rat magnocellular neurones. We first performed chromatin immunoprecipitation followed by genome sequencing (ChIP-seq) to identify Creb3l1 genomic targets and then integrated this data with RNA sequencing data from physiologically stimulated and Creb3l1 knockdown magnocellular neurones.

RESULTS

The data converged on Creb3l1 targets that code for ribosomal proteins and endoplasmic reticulum proteins crucial for the maintenance of cellular proteostasis. We validated genes that compose the PERK arm of the unfolded protein response pathway including Eif2ak3, Eif2s1, Atf4 and Ddit3 as direct Creb3l1 targets. Importantly, knockdown of Creb3l1 in the hypothalamus led to a dramatic depletion in neuropeptide synthesis and secretion. The physiological outcomes from studies of paraventricular and supraoptic nuclei Creb3l1 knockdown animals were changes to food and water consumption.

CONCLUSION

Collectively, our data identify Creb3l1 as a comprehensive controller of the PERK signalling pathway in magnocellular neurones in response to physiological stimulation. The broad regulation of neuropeptide synthesis and secretion by Creb3l1 presents a new therapeutic strategy for metabolic diseases.

Osmoregulation and the Hypothalamic Supraoptic Nucleus: From Genes to Functions

Due to the relatively high permeability to water of the plasma membrane, water tends to equilibrate its chemical potential gradient between the intra and extracellular compartments. Because of this, changes in osmolality of the extracellular fluid are accompanied by changes in the cell volume. Therefore, osmoregulatory mechanisms have evolved to keep the tonicity of the extracellular compartment within strict limits. This review focuses on the following aspects of osmoregulation: 1) the general problems in adjusting the "milieu interieur" to challenges imposed by water imbalance, with emphasis on conceptual aspects of osmosis and cell volume regulation; 2) osmosensation and the hypothalamic supraoptic nucleus (SON), starting with analysis of the electrophysiological responses of the magnocellular neurosecretory cells (MNCs) involved in the osmoreception phenomenon; 3) transcriptomic plasticity of SON during sustained hyperosmolality, to pinpoint the genes coding membrane channels and transporters already shown to participate in the osmosensation and new candidates that may have their role further investigated in this process, with emphasis on those expressed in the MNCs, discussing the relationships of hydration state, gene expression, and MNCs electrical activity; and 4) somatodendritic release of neuropeptides in relation to osmoregulation. Finally, we expect that by stressing the relationship between gene expression and the electrical activity of MNCs, studies about the newly discovered plastic-regulated genes that code channels and transporters in the SON may emerge.

The Impact of Glucocorticoid Therapy on Guideline-Directed Medical Treatment Titration in Patients Hospitalized for Heart Failure with Low Blood Pressure: A Retrospective Study

Background

Positive inotropic and renal protective actions of glucocorticoids have been observed clinically. Therefore, glucocorticoids may be used in patients with heart failure and low blood pressure (HF-LBP).

Methods

The medical records of 144 consecutive patients with HF-LBP who received glucocorticoids as an adjunctive treatment to facilitate the up-titration of β-blocker and angiotensin-converting enzyme inhibitor were reviewed.

Results

After four weeks of treatment, the metoprolol and captopril (or equivalent) dosages were progressively and consistently increased from 25 (interquartile range [IQR] = 12.5-75 mg/day) to 100 mg/day (IQR = 50-178.8 mg/day) and from 0 (IQR = 0-25 mg/day) to 12.5 mg/day (IQR = 0-50 mg/day), respectively. There was a remarkable beneficial hemodynamic response to the glucocorticoid treatment signified by an increase in blood pressure and decrease in heart rate. The average heart rate decreased by 6 beat per minute (bpm) (0.5-16 bpm), and the mean arterial blood pressure increased from 74.06 ± 7.81 to 78.85 ± 7.91 mmHg. We also observed an improvement in renal function and an increased diuretic response following glucocorticoid treatment. As a result, the left ventricular ejection fraction increased from 28.92 ± 8.06% to 33.86 ± 8.76%, and the diuretic response increased from 776.7 mL/40 mg furosemide (IQR = 133.8-2000 mL) to 4000 mL/40 mg furosemide on day 28 (IQR = 2200-5925 mL).

Conclusion

The use of glucocorticoid treatment to maintain hemodynamic and renal functional targets when titrating guideline-directed medical treatment in patients with HF-LBP may be safe, effective, and feasible.

Cardiovascular Neuroendocrinology: Emerging Role for Neurohypophyseal Hormones in Pathophysiology

Arginine vasopressin (AVP) and oxytocin (OXY) are released by magnocellular neurosecretory cells that project to the posterior pituitary. While AVP and OXY currently receive more attention for their contributions to affiliative behavior, this mini-review discusses their roles in cardiovascular function broadly defined to include indirect effects that influence cardiovascular function. The traditional view is that neither AVP nor OXY contributes to basal cardiovascular function, although some recent studies suggest that this position might be re-evaluated. More evidence indicates that adaptations and neuroplasticity of AVP and OXY neurons contribute to cardiovascular pathophysiology.

Osmoregulation of the transcriptome of the hypothalamic supraoptic nucleus: A resource for the community

The hypothalamic supraoptic nucleus (SON) is a core osmoregulatory control centre that deciphers information about the metabolic state of the organism and orchestrates appropriate homeostatic (endocrine) and allostatic (behavioural) responses. We have used RNA sequencing to describe the polyadenylated transcriptome of the SON of the male Wistar Han rat. These data have been mined to generate comprehensive catalogues of functional classes of genes (enzymes, transcription factors, endogenous peptides, G protein coupled receptors, transporters, catalytic receptors, channels and other pharmacological targets) expressed in this nucleus in the euhydrated state, and that together form the basal substrate for its physiological interactions. We have gone on to show that fluid deprivation for 3 days (dehydration) results in changes in the expression levels of 2247 RNA transcripts, which have similarly been functionally catalogued, and further mined to describe enriched gene categories and putative regulatory networks (Regulons) that may have physiological importance in SON function related plasticity. We hope that the revelation of these genes, pathways and networks, most of which have no characterised roles in the SON, will encourage the neuroendocrine community to pursue new investigations into the new 'known-unknowns' reported in the present study.

Physiological and Transcriptomic Changes in the Hypothalamic-Neurohypophysial System after 24 h of Furosemide-Induced Sodium Depletion

BACKGROUND/AIMS

Furosemide is a loop diuretic widely used in clinical practice for the treatment of oedema and hypertension. The aim of this study was to determine physiological and molecular changes in the hypothalamic-neurohypophysial system as a consequence of furosemide-induced sodium depletion.

METHODS

Male rats were sodium depleted by acute furosemide injection (10 and 30 mg/kg) followed by access to low sodium diet and distilled water for 24 h. The renal and behavioural consequences were evaluated, while blood and brains were collected to evaluate the neuroendocrine and gene expression responses.

RESULTS

Furosemide treatment acutely increases urinary sodium and water excretion. After 24 h, water and food intake were reduced, while plasma angiotensin II and corticosterone were increased. After hypertonic saline presentation, sodium-depleted rats showed higher preference for salt. Interrogation using RNA sequencing revealed the expression of 94 genes significantly altered in the hypothalamic paraventricular nucleus (PVN) of sodium-depleted rats (31 upregulated and 63 downregulated). Out of 9 genes chosen, 5 were validated by quantitative PCR in the PVN (upregulated: Ephx2, Ndnf and Vwf; downregulated: Caprin2 and Opn3). The same genes were also assessed in the supraoptic nucleus (SON, upregulated: Tnnt1, Mis18a, Nr1d1 and Dbp; downregulated: Caprin2 and Opn3). As a result of these plastic transcriptome changes, vasopressin expression was decreased in PVN and SON, whilst vasopressin and oxytocin levels were reduced in plasma.

CONCLUSIONS

We thus have identified novel genes that might regulate vasopressin gene expression in the hypothalamus controlling the magnocellular neurons secretory response to body sodium depletion and consequently hypotonic stress.

Caffeine-related effects on cognitive performance: Roles of apoptosis in rat hippocampus following sleep deprivation

Caffeine is a common stimulant widely existed in food and has stimulatory effects on the central nervous system, shift-work individuals often rely on caffeine to maintain attention and keep awake. Although sleep deprivation (SD) is widely considered as an independent risk factor for cognition retardations, however, little is well understood about the synergistic role of caffeine dosage and SD for cognitive performance. This research intended to investigate the underlying molecular mechanism of varying caffeine doses on cognitive function after sleep deprivation. The results revealed that SD attenuated the cognitive dysfunction, associated with ultrastructure damage and pyramidal neuron loss in the hippocampus, decreased in the level of VIP and AVP. SD also significantly accelerated the neuropeptide-associated apoptosis in the hippocampus, which may modulate via the cAMP-PKA-CREB signal path axis and activation of the downstream apoptosis genes. Additionally, the data indicated that low-dose caffeine (LC) contributed to cognitive enhancement, and high-dose caffeine (HC) aggravated cognitive impairment by modulating hippocampal neuronal apoptosis. Our studies suggest that caffeine, particularly in high dosage, may be a potential factor to influence the neurocognitive outcome caused by sleep loss, and the appropriate amount of caffeine ingested after sleep deprivation deserves serious consideration.

Comparative genomics reveals bamboo feeding adaptability in the giant panda (Ailuropoda melanoleuca)

The giant panda (Ailuropoda melanoleuca) is one of the world's most endangered mammals and remains threatened as a result of intense environmental and anthropogenic pressure. The transformation and specialization of the giant panda's diet into a herbivorous diet have resulted in unique adaptabilities in many aspects of their biology, physiology and behavior. However, little is known about their adaptability at the molecular level. Through comparative analysis of the giant panda's genome with those of nine other mammalian species, we found some genetic characteristics of the giant panda that can be associated with adaptive changes for effective digestion of plant material. We also found that giant pandas have similar genetic characteristics to carnivores in terms of olfactory perception but have similar genetic characteristics to herbivores in terms of immunity and hydrolytic enzyme activity. Through the analysis of gene family expansion, 3752 gene families were found, which were enriched in functions such as digestion. A total of 93 genes under positive selection were screened out and gene enrichment identified these genes for the following processes: negative regulation of cellular metabolic process, negative regulation of nitrogen compound metabolic process, negative regulation of macromolecule metabolic process and negative regulation of metabolic process. Combined with the KEGG pathway, it was found that genes such as CREB3L1, CYP450 2S1, HSD11B2, LRPAP1 play a key role in digestion. These genes may have played a key role in the pandas' adaptation to its bamboo diet.

Transcription factor Creb3l1 regulates the synthesis of prohormone convertase enzyme PC1/3 in endocrine cells

Transcription factor cAMP responsive element-binding protein 3 like 1 (Creb3l1) is a non-classical endoplasmic reticulum stress molecule that is emerging as an important component for cellular homeostasis, particularly within cell types with high peptide secretory capabilities. We have previously shown that Creb3l1 serves an important role in body fluid homeostasis through its transcriptional control of the gene coding for antidiuretic hormone arginine vasopressin in the neuropeptide-rich magnocellular neurones of the supraoptic nucleus. In response to osmotic stimuli such as dehydration, vasopressin magnocellular neurones undergo remarkable transcriptome changes, including increased Creb3l1 expression, to ensure that the supply of vasopressin meets demand. To determine where else Creb3l1 fits into the secretory cell supply chain, we performed RNA-sequencing of Creb3l1 knockdown anterior pituitary mouse corticotroph cell line AtT20. The target chosen for further investigation was Pcsk1, which encodes proprotein convertase enzyme 1 (PC1/3). PC1/3 is crucial for processing of neuropeptides and peptide hormones such as pro-opiomelanocortin (POMC), proinsulin, proglucagon, vasopressin and oxytocin. Viral manipulations in supraoptic nuclei by over-expression of Creb3l1 increased Pcsk1, whereas Creb3l1 knockdown decreased Pcsk1 expression. In vitro promoter activity and binding studies showed that Creb3l1 was a transcription factor of the Pcsk1 gene binding directly to a G-box motif in the promoter. In the dehydrated rat anterior pituitary, Creb3l1 and Pcsk1 expression decreased in parallel compared to control, supporting our findings from manipulations in AtT20 cells and the supraoptic nucleus. No relationship was observed between Creb3l1 and Pcsk1 expression in the neurointermediate lobe of the pituitary, indicating a different mechanism of PC1/3 synthesis by these POMC-synthesising cells. Therefore, Creb3l1, by regulating the expression of Pcsk1, does not control the processing of POMC peptides in the intermediate lobe.

Targeting the Glucocorticoid Receptors During Alcohol Withdrawal to Reduce Protracted Neurocognitive Disorders

Persistent regional glucocorticoid (GC) dysregulation in alcohol-withdrawn subjects emerges as a key factor responsible for protracted molecular and neural alterations associated with long-term cognitive dysfunction. Regional brain concentrations of corticosterone vary independently from plasma concentrations in alcohol-withdrawn subjects, which may account for the treatment of alcohol withdrawal-induced persistent pathology. Thus, from a pharmacological point of view, a main issue remains to determine the relative efficacy of compounds targeting the GC receptors to attenuate or suppress the long-lasting persistence of brain regional GC dysfunctions in abstinent alcoholics, as well as persistent changes of neural plasticity. Data from animal research show that acting directly on GC receptors during the withdrawal period, via selective antagonists, can significantly counteract the development and persistence of cognitive and neural plasticity disorders during protracted abstinence. A critical remaining issue is to better assess the relative long-term efficacy of GC antagonists and other compounds targeting the corticotropic axis activity such as gamma-aminobutyric acid A (GABA_A) and GABA_B agonists. Indeed, benzodiazepines (acting indirectly on GABA_A receptors) and baclofen (agonist of the GABA_B receptor) are the compounds most widely used to reduce alcohol dependence. Clinical and preclinical data suggest that baclofen exerts an effective and more powerful counteracting action on such persistent cognitive and endocrine dysfunctions as compared to diazepam, even though its potential negative effects on memory processes, particularly at high doses, should be better taken into account.

The effects of aging on biosynthetic processes in the rat hypothalamic osmoregulatory neuroendocrine system

Elderly people exhibit a diminished capacity to cope with osmotic challenges such as dehydration. We have undertaken a detailed molecular analysis of arginine vasopressin (AVP) biosynthetic processes in the supraoptic nucleus (SON) of the hypothalamus and secretory activity in the posterior pituitary of adult (3 months) and aged (18 months) rats, to provide a comprehensive analysis of age-associated changes to the AVP system. By matrix-assisted laser desorption/ionization time-of-flight mass spectrometry analysis, we identified differences in pituitary peptides, including AVP, in adult and aged rats under both basal and dehydrated states. In the SON, increased Avp gene transcription, coincided with reduced Avp promoter methylation in aged rats. Based on transcriptome data, we have previously characterized a number of novel dehydration-induced regulatory factors involved in the response of the SON to osmotic cues. We found that some of these increase in expression with age, while dehydration-induced expression of these genes in the SON was attenuated in aged rats. In summary, we show that aging alters the rat AVP system at the genome, transcriptome, and peptidome levels. These alterations however did not affect circulating levels of AVP in basal or dehydrated states.

Regulation of cAMP Responsive Element Binding Protein 3-Like 1 (Creb3l1) Expression by Orphan Nuclear Receptor Nr4a1

Cyclic AMP (cAMP) inducible transcription factor cAMP responsive element binding protein 3 like 1 (Creb3l1) is strongly activated in the hypothalamus in response to hyperosmotic cues such as dehydration (DH). We have recently shown that Creb3l1 expression is upregulated by cAMP pathways in vitro, however the exact mechanisms are not known. Here we show that increasing Creb3l1 transcription by raising cAMP levels in mouse pituitary AtT20 cells automatically initiates cleavage of Creb3l1, leading to a greater abundance of the transcriptionally active N-terminal portion. Inhibiting protein synthesis indicated that de novo protein synthesis of an intermediary transcription factor was required for Creb3l1 induction. Strategic mining of our microarray data from dehydrated rodent hypothalamus revealed four candidates, reduced to two by analysis of acute hyperosmotic-induced transcriptional activation profiles in the hypothalamus, and one, orphan nuclear receptor Nr4a1, by direct shRNA mediated silencing in AtT20 cells. We show that activation of Creb3l1 transcription by Nr4a1 involves interaction with a single NBRE site in the promoter region. The ability to activate Creb3l1 transcription by this pathway in vitro is dictated by the level of methylation of a CpG island within the proximal promoter/5′UTR of this gene. We thus identify a novel cAMP-Nr4a1-Creb3l1 transcriptional pathway in AtT20 cells and also, our evidence would suggest, in the hypothalamus.

Structural and functional diversity of nonapeptide hormones from an evolutionary perspective: A review

The article presents an overview of the comparative distribution, structure and functions of the nonapeptide hormones in chordates and non chordates. The review begins with a historical preview of the advent of the concept of neurosecretion and birth of neuroendocrine science, pioneered by the works of E. Scharrer and W. Bargmann. The sections which follow discuss different vertebrate nonapeptides, their distribution, comparison, precursor gene structures and processing, highlighting the major differences in these aspects amidst the conserved features across vertebrates. The vast literature on the anatomical characteristics of the nonapeptide secreting nuclei in the brain and their projections was briefly reviewed in a comparative framework. Recent knowledge on the nonapeptide hormone receptors and their intracellular signaling pathways is discussed and few grey areas which require deeper studies are identified. The sections on the functions and regulation of nonapeptides summarize the huge and ever increasing literature that is available in these areas. The nonapeptides emerge as key homeostatic molecules with complex regulation and several synergistic partners. Lastly, an update of the nonapeptides in non chordates with respect to distribution, site of synthesis, functions and receptors, dealt separately for each phylum, is presented. The non chordate nonapeptides share many similarities with their counterparts in vertebrates, pointing the system to have an ancient origin and to be an important substrate for changes during adaptive evolution. The article concludes projecting the nonapeptides as one of the very first common molecules of the primitive nervous and endocrine systems, which have been retained to maintain homeostatic functions in metazoans; some of which are conserved across the animal kingdom and some are specialized in a group/lineage-specific manner.

An LHX1-Regulated Transcriptional Network Controls Sleep/Wake Coupling and Thermal Resistance of the Central Circadian Clockworks

The suprachiasmatic nucleus (SCN) is the central circadian clock in mammals. It is entrained by light but resistant to temperature shifts that entrain peripheral clocks [1-5]. The SCN expresses many functionally important neuropeptides, including vasoactive intestinal peptide (VIP), which drives light entrainment, synchrony, and amplitude of SCN cellular clocks and organizes circadian behavior [5-16]. The transcription factor LHX1 drives SCN Vip expression, and cellular desynchrony in Lhx1-deficient SCN largely results from Vip loss [17, 18]. LHX1 regulates many genes other than Vip, yet activity rhythms in Lhx1-deficient mice are similar to Vip^-/- mice under light-dark cycles and only somewhat worse in constant conditions. We suspected that LHX1 targets other than Vip have circadian functions overlooked in previous studies. In this study, we compared circadian sleep and temperature rhythms of Lhx1- and Vip-deficient mice and found loss of acute light control of sleep in Lhx1 but not Vip mutants. We also found loss of circadian resistance to fever in Lhx1 but not Vip mice, which was partially recapitulated by heat application to cultured Lhx1-deficient SCN. Having identified VIP-independent functions of LHX1, we mapped the VIP-independent transcriptional network downstream of LHX1 and a largely separable VIP-dependent transcriptional network. The VIP-independent network does not affect core clock amplitude and synchrony, unlike the VIP-dependent network. These studies identify Lhx1 as the first gene required for temperature resistance of the SCN clockworks and demonstrate that acute light control of sleep is routed through the SCN and its immediate output regions.