Simulated effects of tidal inundation and light reduction on Zostera muelleri flowering in seagrass nurseries.

Zostera muelleri is an abundant seagrass species distributed through intertidal and shallow subtidal waters on the subtropical coasts of Australia. The vertical distribution of Zostera is likely defined by tidal influences, particularly desiccation and light reduction stresses. These stresses were expected to affect the flowering of Z. muelleri; however, it is difficult to quantify the effects of tidal inundation with field studies due to multiple confounding environmental factors affecting flowering (e.g., water temperature, herbivory, nutrients). A laboratory aquarium experiment compared the effects of two levels of tidal height (intertidal and subtidal) and light intensity (shaded and unshaded) on flowering timing, abundance, the ratio between flowering shoots and vegetative shoots, the morphology and duration of flower development. The earliest and greatest flowering intensity was recorded in the subtidal-unshaded group, with no flowers observed in the intertidal-shaded group. Notably, the peak flowering time was the same across shaded and unshaded treatments. Shading prolonged the timing of the first flowering and reduced the density of flowering shoots and spathes, while tidal inundation had a more significant effect on the density of flowering shoots and the density of spathes. Results showed that Z. muelleri could flower under low light conditions or tidal stress but not when exposed to both stresses simultaneously in a laboratory 'nursery setting'. Therefore, applying subtidal-unshaded conditions appears to be beneficial for seagrass nurseries aimed at improved flower abundance despite the plants previously being collected from and adapted to intertidal meadows. Further studies that explore the suitable conditions for triggering and optimising the flowering will be beneficial in designing cost-effective seagrass nurseries.

Humate application alters microbiota-mineral interactions and assists in pasture dieback recovery.

Pasture dieback is a rapidly expanding decaying pasture syndrome that affects millions of hectares of agricultural land in Queensland, Australia, making it useless for the cattle industry and decimating farmers' income and welfare. Since the syndrome was first identified in the early 1990s, farmers and agronomists have tried various methods for pasture recovery, including slashing, burning, ploughing and resowing grass, fertilising, destocking, and overstocking. In most cases, after a minimal initial improvement, the grass reverts to dieback within a few weeks. Here, we present an application of potassium humate, a well-known plant growth stimulator, as a possible long-term recovery option. Humate was applied once at the rate of 12 ml per m2. Humate application did not alter the alpha or beta diversity of soil bacterial communities, nor did it change the mineral profile in the soil. However, humate application altered soil microbiota-mineral temporal interactions and introduced subtle changes in the microbial community that could assist pasture recovery. A single humate application increased paddock plant biomass significantly up to 20 weeks post-application. Eleven months after the single application, the paddock was grazed to the ground by the cattle just before the rainfall season. After pasture regrowth, the humate-treated plots significantly improved root morphometric indicators for both grass and dicots and increased the ratio of grass/weeds by 27.6% compared to the water-treated control. While this treatment will not resolve the dieback syndrome, our results invite more research to optimise the use of humate for maximum economic benefit in paddock use under pasture dieback syndrome conditions.

G-protein coupled estrogen receptor (GPER1) activation promotes synaptic insertion of AMPA receptors and induction of chemical LTP at hippocampal temporoammonic-CA1 synapses.

It is well documented that 17ß estradiol (E2) regulates excitatory synaptic transmission at hippocampal Shaffer-collateral (SC)-CA1 synapses, via activation of the classical estrogen receptors (ERα and ERß). Hippocampal CA1 pyramidal neurons are also innervated by the temporoammonic (TA) pathway, and excitatory TA-CA1 synapses are reported to be regulated by E2. Recent studies suggest a role for the novel G-protein coupled estrogen receptor (GPER1) at SC-CA1 synapses, however, the role of GPER1 in mediating the effects of E2 at juvenile TA-CA1 synapses is unclear. Here we demonstrate that the GPER1 agonist, G1 induces a persistent, concentration-dependent (1-10 nM) increase in excitatory synaptic transmission at TA-CA1 synapses and this effect is blocked by selective GPER1 antagonists. The ability of GPER1 to induce this novel form of chemical long-term potentiation (cLTP) was prevented following blockade of N-methyl-D-aspartate (NMDA) receptors, and it was not accompanied by any change in paired pulse facilitation ratio (PPR). GPER1-induced cLTP involved activation of ERK but was independent of phosphoinositide 3-kinase (PI3K) signalling. Prior treatment with philanthotoxin prevented the effects of G1, indicating that synaptic insertion of GluA2-lacking α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors underlies GPER1-induced cLTP. Furthermore, activity-dependent LTP occluded G1-induced cLTP and vice versa, indicating that these processes have overlapping expression mechanisms. Activity-dependent LTP was blocked by the GPER1 antagonist, G15, suggesting that GPER1 plays a role in NMDA-dependent LTP at juvenile TA-CA1 synapses. These findings add a new dimension to our understanding of GPER1 in modulating neuronal plasticity with relevance to age-related neurodegenerative conditions.

Simulated megaherbivore grazing as a driver of seagrass flowering.

Seagrass meadows are an important habitat for Testudines (sea turtles) and Sirenia (dugong and manatee) megaherbivores. Megaherbivores can influence the structuring of seagrass meadows; for example, foraging patterns have been found to relate to seagrass phenological strategy. However, as these observations are derived from uncontrolled field studies, it is unclear whether grazing drives such changes or if the changes are related to other factors (e.g., temperature, tidal depth, light). In the present study, a mesocosm experiment was designed to test the impacts of grazing on metrics of flowering of Zostera muelleri over two consecutive flowering seasons. Prior to each flowering season, plants were cropped to 3 cm and 1 cm lengths to represent turtle and dugong grazing, respectively. This study measured the timing of flowering, the number of flowering shoots, the height of the flowering shoot, and the number of spathes (sheathing bracts containing seeds) per flowering shoot in each replicate (n = 5) weekly. Cropping had no significant influence on the timing of flowering (i.e., number of days to first and peak flowering) indicating that it is not a trigger for flowering. However, cropping significantly reduced the maximum density of flowering shoots and spathes, which was proposed to be due to resource allocation differences between clonal growth and flower production. A reduction in the flowering ratio was observed in both cropped plant groups and the relatively high density and the ratio of flowering observed in the 1 cm group indicate that the plant was adapting to cope with stress. Morphology of flowering (i.e., the maximum height of flowering shoot and the maximum number of spathes per flowering shoot) was not significantly affected by cropping and these two variables were strongly correlated. The results suggest that cropping can influence the overall flowering densities in a season but not the timing of flowering. This study demonstrated that cropping prior to the flowering season can reduce the expected production of spathes in seed nurseries and suggests it may be beneficial to consider megaherbivores in seed-based restoration activities.

Regulation of hippocampal synaptic function by the metabolic hormone leptin: Implications for health and disease.

Significant advances have been made in our understanding of the hormone, leptin and its CNS actions in recent years. It is now evident that leptin has a multitude of brain functions, that extend beyond its established role in the hypothalamic control of energy balance. Additional brain regions including the hippocampus are important targets for leptin, with a high density of leptin receptors (LepRs) expressed in specific hippocampal regions and localised to CA1 synapses. Extensive evidence indicates that leptin has pro-cognitive actions, as it rapidly modifies synaptic efficacy at excitatory Schaffer collateral (SC)-CA1 and temporoammonic (TA)-CA1 synapses and enhances performance in hippocampal-dependent memory tasks. There is a functional decline in hippocampal responsiveness to leptin with age, with significant reductions in the modulatory effects of leptin at SC-CA1 and TA-CA1 synapses in aged, compared to adult hippocampus. As leptin has pro-cognitive effects, this decline in leptin sensitivity is likely to have negative consequences for cognitive function during the aging process. Here we review how evaluation of the hippocampal actions of leptin has improved our knowledge of the regulatory brain functions of leptin in health and provided significant insight into the impact of leptin in age-related neurodegenerative disorders linked to cognitive decline.

Validation of MicroRNA-188-5p Inhibition Power on Tumor Cell Proliferation in Papillary Thyroid Carcinoma.

Given the crucial role of microRNAs in the cellular proliferation of various types of cancers, we aimed to analyze the expression and function of a cellular proliferation-associated miR-188-5p in papillary thyroid carcinoma (PTC). Here we demonstrate that miR-188-5p is downregulated in PTC tumor tissues compared with the associated noncancerous tissues. We also validate that the miR-188-5p overexpression suppressed the PTC cancer cell proliferation. In addition, fibroblast growth factor 5 (FGF5) is observed to be downregulated in the PTC tumor tissues compared with the associated noncancerous tissues. Subsequently, FGF5 is identified as the direct functional target of miR-188-5p. Moreover, the silencing of FGF5 was found to inhibit PTC cell proliferation, which is the same pattern as miR-188-5p overexpression. These results suggest that miR-188-5p-associated silencing of FGF5 inhibits tumor cell proliferation in PTC. It also highlights the importance of further evaluating miR-188-5p as a potential biomarker and therapy target in PTC.

N-Palmitoylglycine and other N-acylamides activate the lipid receptor G2A/GPR132.

The G-protein-coupled receptor GPR132, also known as G2A, is activated by 9-hydroxyoctadecadienoic acid (9-HODE) and other oxidized fatty acids. Other suggested GPR132 agonists including lysophosphatidylcholine (LPC) have not been readily reproduced. Here, we identify N-acylamides in particular N-acylglycines, as lipid activators of GPR132 with comparable activity to 9-HODE. The order-of-potency is N-palmitoylglycine > 9-HODE ≈ N-linoleoylglycine > linoleamide > N-oleoylglycine ≈ N-stereoylglycine > N-arachidonoylglycine > N-docosehexanoylglycine. Physiological concentrations of N-acylglycines in tissue are sufficient to activate GPR132. N-linoleoylglycine and 9-HODE also activate rat and mouse GPR132, despite limited sequence conservation to human. We describe pharmacological tools for GPR132, identified through drug screening. SKF-95667 is a novel GPR132 agonist. SB-583831 and SB-583355 are peptidomimetic molecules containing core amino acids (glycine and phenylalanine, respectively), and structurally related to previously described ligands. A telmisartan analog, GSK1820795A, antagonizes the actions of N-acylamides at GPR132. The synthetic cannabinoid CP-55 940 also activates GPR132. Molecular docking to a homology model suggested a site for lipid binding, predicting the acyl side-chain to extend into the membrane bilayer between TM4 and TM5 of GPR132. Small-molecule ligands are envisaged to occupy a "classical" site encapsulated in the 7TM bundle. Structure-directed mutagenesis indicates a critical role for arginine at position 203 in transmembrane domain 5 to mediate GPR132 activation by N-acylamides. Our data suggest distinct modes of binding for small-molecule and lipid agonists to the GPR132 receptor. Antagonists, such as those described here, will be vital to understand the physiological role of this long-studied target.

GPR55 controls functional differentiation of self-renewing epithelial progenitors for salivation.

GPR55, a lipid-sensing receptor, is implicated in cell cycle control, malignant cell mobilization, and tissue invasion in cancer. However, a physiological role for GPR55 is virtually unknown for any tissue type. Here, we localize GPR55 to self-renewing ductal epithelial cells and their terminally differentiated progeny in both human and mouse salivary glands. Moreover, we find GPR55 expression downregulated in salivary gland mucoepidermoid carcinomas and GPR55 reinstatement by antitumor irradiation, suggesting that GPR55 controls renegade proliferation. Indeed, GPR55 antagonism increases cell proliferation and function determination in quasiphysiological systems. In addition, Gpr55-/- mice present ~50% enlarged submandibular glands with many more granulated ducts, as well as disordered endoplasmic reticuli and with glycoprotein content. Next, we hypothesized that GPR55 could also modulate salivation and glycoprotein content by entraining differentiated excretory progeny. Accordingly, GPR55 activation facilitated glycoprotein release by itself, inducing low-amplitude Ca2+ oscillations, as well as enhancing acetylcholine-induced Ca2+ responses. Topical application of GPR55 agonists, which are ineffective in Gpr55-/- mice, into adult rodent submandibular glands increased salivation and saliva glycoprotein content. Overall, we propose that GPR55 signaling in epithelial cells ensures both the life-long renewal of ductal cells and the continuous availability of saliva and glycoproteins for oral health and food intake.

'The world is full of magic things, patiently waiting for our senses to grow sharper' (WB Yeats): enhancing resilience among deaf young people in South Africa through photography and filmmaking.

This article concerns deaf children and young people living in South Africa who are South African Sign Language users and who participated in an interdisciplinary research project using the medium of teaching film and photography with the goal of enhancing resilience. Specifically, this paper explores three questions that emerged from the deaf young people's experience and involvement with the project: (i) What is disclosed about deaf young people's worldmaking through the filmic and photographic modality? (ii) What specific impacts do deaf young people's ontologically visual habitations of the world have on the production of their film/photographic works? (iii) How does deaf young people's visual, embodied praxis through film and photography enable resilience? The presentation of findings and related theoretical discussion is organised around three key themes: (i) 'writing' into reality through photographic practice, (ii) filmmaking as embodied emotional praxis and (iii) enhancing resilience through visual methodologies. The discussion is interspersed with examples of the young people's own work.

Age-dependent regulation of excitatory synaptic transmission at hippocampal temporoammonic-CA1 synapses by leptin.

The hippocampus is a key target for the hormone leptin and leptin regulation of excitatory synaptic transmission at Schaffer-collateral-CA1 synapses during aging are well documented. However, little is known about the age-dependent actions of leptin at the temporoammonic (TA) input to CA1 neurons. Here we show that leptin induces a novel form of N-methyl-D-aspartate receptor-dependent long-term depression (LTD) at adult (12-24 weeks old) TA-CA1 synapses. Leptin-induced LTD requires activation of canonical Janus tyrosine kinase 2- signal transducer and activator of transcription signaling and removal of GluA1-containing α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors from synapses. Moreover, leptin-induced LTD is occluded by activity-dependent LTD at TA-CA1 synapses. By contrast, leptin has no effect on excitatory synaptic transmission at aged (12-14 months old) TA-CA1 synapses, and low-frequency stimulation also fails to induce LTD at this age. These findings demonstrate clear age-related alterations in the leptin sensitivity of TA-CA1 synapses and provide valuable information on how the leptin system alters with age. As leptin has been linked to Alzheimer's disease, these findings have important implications for understanding of age-related disorders such as Alzheimer's disease.

Potential mechanisms of calcium dependent regulation of the mammalian cell cycle revealed by comprehensive unbiased label-free nLC-MS/MS quantitative proteomics.

Calcium (Ca2+) controls progression through the mammalian cell cycle by engaging a diverse range of molecular pathways. While the essential role of spatio-temporal Ca2+ signalling in the cell cycle is well established, the precise mechanisms by which it regulates cell cycle entry and progression through G1 are not particularly well understood. Here, high-resolution label-free semi-quantitative nLC-MS/MS analysis has been used to support a highly reproducible unbiased analysis of Ca2+ influx dependent growth factor induced protein expression early in G1 in human fibroblasts. Using this strategy a panel of 182 proteins whose expression was Ca2+ dependent were identified. Pathway analysis has indicated that Ca2+ likely regulates cell proliferation via PI3K/AKT pathway and its downstream target mTOR. In addition to cell proliferation found proteins were involved in the regulation of cell morphology and cellular assembly and organization, the environmental clues, which are known to regulate G1 progression. Reported here data represents one of the most comprehensive proteomic datasets of growth factor and Ca2+ dependent protein expression in the mammalian cell cycle and provides a rich source of publically available data to support continued investigation of the role of Ca2+ in G1 progression at both the molecular and systems level. BIOLOGICAL SIGNIFICANCE: The results of this study provide new insight into Ca2+ dependent regulation of cell cycle. This manuscript reports first to date global analysis of Ca2+ regulated protein expression changes early in G1 in non-transformed human fibroblast cell line. It also highlights canonical signalling pathways and biological processes that are regulated by the inhibition of Ca2+ influx. Importantly, it appears that Ca2+ may be the factor that links cell division with environmental cues, cell morphology and cellular assembly and organization, on which cell proliferation depends. Hence, the findings presented here provide numerous opportunities for more detailed investigations of the mechanism of Ca2+ dependent regulation of cell cycle at the molecular and systemic level.

Cannabinoid Receptor-Related Orphan G Protein-Coupled Receptors.

Of the druggable group of G protein-coupled receptors in the human genome, a number remain which have yet to be paired with an endogenous ligand-orphan GPCRs. Among these 100 or so entities, 3 have been linked to the cannabinoid system. GPR18, GPR55, and GPR119 exhibit limited sequence homology with the established CB1 and CB2 cannabinoid receptors. However, the pharmacology of these orphan receptors displays overlap with CB1 and CB2 receptors, particularly for GPR18 and GPR55. The linking of GPR119 to the cannabinoid receptors is less convincing and emanates from structural similarities of endogenous ligands active at these GPCRs, but which do not cross-react. This review describes the evidence for describing these orphan GPCRs as cannabinoid receptor-like receptors.

Big conductance calcium-activated potassium channel openers control spasticity without sedation.

BACKGROUND AND PURPOSE: Our initial aim was to generate cannabinoid agents that control spasticity, occurring as a consequence of multiple sclerosis (MS), whilst avoiding the sedative side effects associated with cannabis. VSN16R was synthesized as an anandamide (endocannabinoid) analogue in an anti-metabolite approach to identify drugs that target spasticity. EXPERIMENTAL APPROACH: Following the initial chemistry, a variety of biochemical, pharmacological and electrophysiological approaches, using isolated cells, tissue-based assays and in vivo animal models, were used to demonstrate the activity, efficacy, pharmacokinetics and mechanism of action of VSN16R. Toxicological and safety studies were performed in animals and humans. KEY RESULTS: VSN16R had nanomolar activity in tissue-based, functional assays and dose-dependently inhibited spasticity in a mouse experimental encephalomyelitis model of MS. This effect occurred with over 1000-fold therapeutic window, without affecting normal muscle tone. Efficacy was achieved at plasma levels that are feasible and safe in humans. VSN16R did not bind to known CB1 /CB2 /GPPR55 cannabinoid-related receptors in receptor-based assays but acted on a vascular cannabinoid target. This was identified as the major neuronal form of the big conductance, calcium-activated potassium (BKCa ) channel. Drug-induced opening of neuronal BKCa channels induced membrane hyperpolarization, limiting excessive neural-excitability and controlling spasticity. CONCLUSIONS AND IMPLICATIONS: We identified the neuronal form of the BKCa channel as the target for VSN16R and demonstrated that its activation alleviates neuronal excitability and spasticity in an experimental model of MS, revealing a novel mechanism to control spasticity. VSN16R is a potential, safe and selective ligand for controlling neural hyper-excitability in spasticity.

Canonical JAK-STAT signaling is pivotal for long-term depression at adult hippocampal temporoammonic-CA1 synapses.

The Janus kinase (JAK)-signal transducer and activator of transcription (STAT) signaling pathway is involved in numerous cellular processes and it is implicated in neurodegenerative disorders, like Alzheimer disease. Recent studies identified a crucial role for this pathway in activity-dependent long-term depression (LTD) at hippocampal Schaffer collateral (SC)-CA1 synapses. However, it is unclear whether JAK-STAT signaling also regulates excitatory synaptic function at the anatomically distinct temporoammonic (TA) input to CA1 neurons. Here we demonstrate that LTD at adult TA-CA1 synapses involves JAK-STAT signaling, but unlike SC-CA1 synapses, requires rapid gene transcription. TA-CA1 LTD requires NMDA receptor activation and is independent of PI3K or ERK signaling. JAK-STAT signaling was critical for TA-CA1 LTD as inhibition of JAK or STAT blocked LTD induction and prevented NMDA-induced AMPA (α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid) receptor internalization in hippocampal neurons. Moreover, an increase in phosphorylated JAK2 and STAT3 accompanied chemical induction of LTD and AMPA receptor internalization. STAT3-driven gene transcription was required for LTD as inhibition of STAT3-DNA binding, nuclear export, and gene transcription all prevented LTD induction. These data indicate an essential role for canonical JAK-STAT signaling in activity-dependent LTD at TA-CA1 synapses and provide valuable insight into the role of the TA input in hippocampal synaptic plasticity.-McGregor, G., Irving, A. J., Harvey, J. Canonical JAK-STAT signaling is pivotal for long-term depression at adult hippocampal temporoammonic-CA1 synapses.

Testing for thresholds of ecosystem collapse in seagrass meadows.

Although the public desire for healthy environments is clear-cut, the science and management of ecosystem health has not been as simple. Ecological systems can be dynamic and can shift abruptly from one ecosystem state to another. Such unpredictable shifts result when ecological thresholds are crossed; that is, small cumulative increases in an environmental stressor drive a much greater change than could be predicted from linear effects, suggesting an unforeseen tipping point is crossed. In coastal waters, broad-scale seagrass loss often occurs as a sudden event associated with human-driven nutrient enrichment (eutrophication). We tested whether the response of seagrass ecosystems to coastal nutrient enrichment is subject to a threshold effect. We exposed seagrass plots to different levels of nutrient enrichment (dissolved inorganic nitrogen) for 10 months and measured net production. Seagrass response exhibited a threshold pattern when nutrient enrichment exceeded moderate levels: there was an abrupt and large shift from positive to negative net leaf production (from approximately 0.04 leaf production to 0.02 leaf loss per day). Epiphyte load also increased as nutrient enrichment increased, which may have driven the shift in leaf production. Inadvertently crossing such thresholds, as can occur through ineffective management of land-derived inputs such as wastewater and stormwater runoff along urbanized coasts, may account for the widely observed sudden loss of seagrass meadows. Identification of tipping points may improve not only adaptive-management monitoring that seeks to avoid threshold effects, but also restoration approaches in systems that have crossed them.

Species coexistence and the superior ability of an invasive species to exploit a facilitation cascade habitat.

Facilitation cascades generated by co-occurring foundation species can enhance the abundance and diversity of associated organisms. However, it remains poorly understood how differences among native and invasive species in their ability to exploit these positive interactions contribute to emergent patterns of community structure and biotic acceptance. On intertidal shorelines in New England, we examined the patterns of coexistence between the native mud crabs and the invasive Asian shore crab in and out of a facilitation cascade habitat generated by mid intertidal cordgrass and ribbed mussels. These crab species co-occurred in low intertidal cobbles adjacent to the cordgrass-mussel beds, despite experimental findings that the dominant mud crabs can kill and displace Asian shore crabs and thereby limit their successful recruitment to their shared habitat. A difference between the native and invasive species in their utilization of the facilitation cascade likely contributes to this pattern. Only the Asian shore crabs inhabit the cordgrass-mussel beds, despite experimental evidence that both species can similarly benefit from stress amelioration in the beds. Moreover, only Asian shore crabs settle in the beds, which function as a nursery habitat free of lethal mud crabs, and where their recruitment rates are particularly high (nearly an order of magnitude higher than outside beds). Persistence of invasive adult Asian shore crabs among the dominant native mud crabs in the low cobble zone is likely enhanced by a spillover effect of the facilitation cascade in which recruitment-limited Asian shore crabs settle in the mid intertidal cordgrass-mussel beds and subsidize their vulnerable populations in the adjacent low cobble zone. This would explain why the abundances of Asian shore crabs in cobbles are doubled when adjacent to facilitation cascade habitats. The propensity for this exotic species to utilize habitats created by facilitation cascades, despite the lack of a shared evolutionary history, contributes to species coexistence and the acceptance of invasives into a diverse community.

Identifying knowledge gaps in seagrass research and management: An Australian perspective.

Seagrass species form important marine and estuarine habitats providing valuable ecosystem services and functions. Coastal zones that are increasingly impacted by anthropogenic development have experienced substantial declines in seagrass abundance around the world. Australia, which has some of the world's largest seagrass meadows and is home to over half of the known species, is not immune to these losses. In 1999 a review of seagrass ecosystems knowledge was conducted in Australia and strategic research priorities were developed to provide research direction for future studies and management. Subsequent rapid evolution of seagrass research and scientific methods has led to more than 70% of peer reviewed seagrass literature being produced since that time. A workshop was held as part of the Australian Marine Sciences Association conference in July 2015 in Geelong, Victoria, to update and redefine strategic priorities in seagrass research. Participants identified 40 research questions from 10 research fields (taxonomy and systematics, physiology, population biology, sediment biogeochemistry and microbiology, ecosystem function, faunal habitats, threats, rehabilitation and restoration, mapping and monitoring, management tools) as priorities for future research on Australian seagrasses. Progress in research will rely on advances in areas such as remote sensing, genomic tools, microsensors, computer modeling, and statistical analyses. A more interdisciplinary approach will be needed to facilitate greater understanding of the complex interactions among seagrasses and their environment.

Emerging roles for the novel estrogen-sensing receptor GPER1 in the CNS.

Estrogens play a key role in regulating reproductive and neuroendocrine function by activating classical nuclear steroid receptors that act as ligand gated transcription factors. However evidence is growing that estrogens also promote rapid non-genomic responses via activation of membrane-associated estrogen receptors. The G protein-coupled estrogen receptor (GPER1; also known as GPR30) has been identified as one of the main estrogen-sensitive receptors responsible for the rapid non-genomic actions of estrogen. In recent years, our understanding of the CNS actions of GPER1s has significantly increased following the development of selective pharmacological tools and via the use of transgenic technologies to knockout GPER1 in mice. Here we review recent advances that have been made to uncover the role of GPER1s in the CNS. This article is part of the Special Issue entitled 'Lipid Sensing G Protein-Coupled Receptors in the CNS'.

Modulation of l-α-lysophosphatidylinositol/GPR55 MAP kinase signalling by CB2 receptor agonists: identifying novel GPR55 inhibitors.

BACKGROUND: GPR55 is a lipid-sensing G protein-coupled receptor that is activated by the endogenous lipid l-α-lysophosphatidylinositol (LPI) and can be modulated by certain cannabinoid ligands. METHODS: In this study we investigated the GPR55 activity of four synthetic CB2 receptor agonists using the AlphaScreen® SureFire® assay. RESULTS: Here we show that the CB2 receptor-selective agonists HU-308, HU-433 and HU-910 do not promote GPR55-mediated ERK1/2 phosphorylation up to a concentration of 3 µM. However, LPI-induced ERK1/2 phosphorylation is inhibited by the (-)-enantiomer of HU-308, designated HU-433, whereas HU-308 has no effect on LPI activity. The carboxylic analogue of HU-910, designated HU-914, potently inhibits LPI-induced ERK1/2 phosphorylation; however, HU-914 was less effective, with potential biphasic effects. CONCLUSIONS: This structure-activity-relationship study has identified novel ligands which act both as CB2 receptor agonists and GPR55 modulators and related compounds that lack GPR55 activity.

Identification of Novel GPR55 Modulators Using Cell-Impedance-Based Label-Free Technology.

The orphan G protein-coupled receptor GPR55 has been proposed as a novel receptor of the endocannabinoid system. However, the validity of this categorization is still under debate mainly because of the lack of potent and selective agonists and antagonists of GPR55. Binding assays are not yet available for GPR55 screening, and discrepancies in GPR55 mediated signaling pathways have been reported. In this context, we have designed and synthesized novel GPR55 ligands based on a chromenopyrazole scaffold. Appraisal of GPR55 activity was accomplished using a label-free cell-impedance-based assay in hGPR55-HEK293 cells. The real-time impedance responses provided an integrative assessment of the cellular consequence to GPR55 stimulation taking into account the different possible signaling pathways. Potent GPR55 partial agonists (14b, 18b, 19b, 20b, and 21-24) have been identified; one of them (14b) being selective versus classical cannabinoid receptors. Upon antagonist treatment, chromenopyrazoles 21-24 inhibited lysophosphatidylinositol (LPI) effect. One of these GPR55 antagonists (21) is fully selective versus classic cannabinoid receptors. Compared to LPI, the predicted physicochemical parameters of the new compounds suggest a clear pharmacokinetic improvement.