Receptor Class Research Articles

Adaptive sampling-based structural prediction reveals opening of a GABAA receptor through the αβ interface.

γ-Aminobutyric acid type A (GABAA) receptors are ligand-gated ion channels in the central nervous system with largely inhibitory function. Despite being a target for drugs including general anesthetics and benzodiazepines, experimental structures have yet to capture an open state of classical synaptic α1β2γ2 GABAA receptors. Here, we use a goal-oriented adaptive sampling strategy in molecular dynamics simulations followed by Markov state modeling to capture an energetically stable putative open state of the receptor. The model conducts chloride ions with comparable conductance as in electrophysiology measurements. Relative to experimental structures, our open model is relatively expanded at both the cytoplasmic (-2') and central (9') gates, coordinated with distinctive rearrangements at the transmembrane αβ subunit interface. Consistent with previous experiments, targeted substitutions disrupting interactions at this interface slowed the open-to-desensitized transition rate. This work demonstrates the capacity of advanced simulation techniques to investigate a computationally and experimentally plausible functionally critical of a complex membrane protein yet to be resolved by experimental methods.

Cholesterol metabolites modulate ionotropic P2X4 and P2X7 receptor current in microglia cells.

The central nervous system is a well-known steroidogenic tissue producing, among others, cholesterol metabolites such as neuroactive steroids, oxysterols and steroid hormones. It is well known that these endogenous molecules affect several receptor classes, including ionotropic GABAergic and NMDA glutamatergic receptors in neurons. It has been shown that also ionotropic purinergic (P2X) receptors are cholesterol metabolites' targets. Among P2X receptors, purinergic P2X4 and P2X7 receptors are expressed in microglia, the innate immune cells involved in the brain inflammatory response. In this study, we explore the ionotropic purinergic receptors modulation by cholesterol metabolites in microglia. Patch-clamp experiments were performed in BV2 cells, a murine microglia cell line, to evaluate effects of cholesterol metabolites using micro- and nanomolar concentrations. About P2X4 receptor, we found that testosterone butyrate (20μM and 200nM) and allopregnanolone (10μM and 100nM) both potentiated its current, while neither 25-hydroxycholesterol (10μM and 100nM) nor 17β-estradiol (1μM) showed any effects. On the other hand, P2X7 receptor current was potentiated by allopregnanolone (10μM) and 25-hydroxycholesterol (10μM and 100nM). Taken together, our data show that modulation of either P2X4 and P2X7 current is affected differently by cholesterol metabolites, suggesting a structure-activity relationship among these players. Identifying the possible link between purinergic transmission, microglia and cholesterol metabolites will allow to define new targets for drug development to treat neuroinflammation.

Damsin and neoambrosin: Two sesquiterpene lactones with affinity and different activity for PPAR and TRPA1 receptors.

Ambrosia maritima L. (family Asteraceae) is an annual herb widely distributed throughout the Mediterranean region and Africa. The herb is employed in folk medicine for the treatment of many ailments. Herein, we report a comprehensive investigation of the diverse biological potential of two sesquiterpene lactones, damsin and neoambrosin, isolated from Ambrosia maritima. 1D and 2D NMR and HR-ESI-MS/MS were employed to characterize the chemical structures of both compounds. In order to identify biological targets of both compounds we investigated their potential affinity for peroxisome proliferator-activated receptors (PPARs) and transient receptor potential (TRP) channels, which are pleiotropic classes of receptors implicated in essential functions of the body. This was investigated using a luciferase assay and a calcium fluorometric assay. A carbonic anhydrase inhibition assay was also performed using stopped flow CO2 hydrase spectrophotometric assay. Our analysis revealed that unlike damsin, neoambrosin showed a selective partial agonist effect on PPARγ receptors and TRPA1 channels. Its binding mode was investigated through in silico analysis. Both compounds showed no affinity for the tested carbonic anhydrases. Overall, our study details the chemical properties of neoambrosin and damsin and highlights neoambrosin as novel, cost-effective partial agonist of PPARɣ and TRPA1 receptors despite additional in vivo studies are needed to elucidate its biological and pharmacological properties.

The novel ECM protein SNED1 mediates cell adhesion via the RGD-binding integrins α5β1 and αvβ3.

The extracellular matrix (ECM) is a complex meshwork comprising over 100 proteins. It serves as an adhesive substrate for cells and, hence, plays critical roles in health and disease. We have recently identified a novel ECM protein, SNED1, and have found that it is required for neural crest cell migration and craniofacial morphogenesis during development and in breast cancer, where it is necessary for the metastatic dissemination of tumor cells. Interestingly, both processes involve the dynamic remodeling of cell-ECM adhesions via cell surface receptors. Sequence analysis revealed that SNED1 contains two amino acid motifs, RGD and LDV, known to bind integrins, the largest class of ECM receptors. We thus sought to investigate the role of SNED1 in cell adhesion. Here, we report that SNED1 mediates breast cancer and neural crest cell adhesion via its RGD motif. We further demonstrate that cell adhesion to SNED1 is mediated by the RGD integrins α5β1 and αvβ3. These findings are a first step toward identifying the signaling pathways activated downstream of the SNED1-integrin interactions guiding craniofacial morphogenesis and breast cancer metastasis.

Variations of blood D-serine and D-aspartate homeostasis track psychosis stages

Schizophrenia (SCZ) is a severe psychotic disorder characterized by a disruption in glutamatergic NMDA receptor (NMDAR)-mediated neurotransmission. Compelling evidence has revealed that NMDAR activation is not limited to L-glutamate, L-aspartate, and glycine since other free amino acids (AAs) in the atypical D-configuration, such as D-aspartate and D-serine, also modulate this class of glutamatergic receptors. Although dysregulation of AAs modulating NMDARs has been previously reported in SCZ, it remains unclear whether distinct variations of these biomolecules occur during illness progression from at-risk premorbid to clinically manifest stage. To probe this issue, we used High-Performance Liquid Chromatography (HPLC) to measure serum levels of D- and L-AAs that stimulate NMDARs across four groups of individuals diagnosed with (a) At-Risk Mental State (ARMS) for psychosis, (b) First Episode of Psychosis (FEP), (c) full-blown SCZ and (d) Healthy Donors (HD). We examined how diagnosis, demographic features, and antipsychotic treatment influence the variation of AA levels throughout psychosis progression. Finally, we explored the potential association between AA blood concentrations and clinical and cognitive measures related to psychosis. Our findings identified inter-group differences in serum AA composition, highlighting that the upregulation of D-serine/total serine and D-aspartate/total aspartate ratios represent a peculiar blood biochemical signature of early stages of psychosis progression, while increased L-glutamate, L-aspartate and glycine associate with chronic SCZ diagnosis. The present findings provide direct evidence for early dysregulation of D-AA metabolism and have potential implications for the identification of biomarkers for the early detection and staging of psychosis.

SEC14L2 regulates the transport of cholesterol in non-small cell lung cancer through SCARB1

BackgroundInhibiting cholesterol metabolism has shown great potential in non-small cell lung cancer (NSCLC). However, the regulatory mechanism of the lipid metabolism key factor Sect. 14-like lipid binding 2 (SEC14L2) in NSCLC remains unclear. This study investigates the effects of differentially expressed genes related to cholesterol metabolism on the development of NSCLC.MethodsCox regression and survival analysis were performed to screen cholesterol metabolism-related genes and predict survival prognosis in NSCLC patients. The proliferation and migration of NSCLC cells were assessed by CCK-8, EdU, colony formation and wound-healing assay. Cholesterol depletion and rescue trials were used to evaluate the effect of SEC14L2 on cholesterol transport in NSCLC cells. IF and Co-IP were used to analyze the targeting relationship between SEC14L2 and scavenger receptor class B member 1 (SCARB1).ResultsSEC14L2 was a key gene related to prognosis in NSCLC patients and was highly expressed in A549 and Calu-1 cells. Subsequent studies demonstrated that knockdown of SEC14L2 significantly reduced the proliferation and migration of NSCLC cells, resulting in inhibited tumor growth. Furthermore, both in vitro and in vivo experiments indicated that SEC14L2 regulated cholesterol uptake. Silencing SEC14L2 partially counteracted the promotion of cholesterol content by MβCD-chol in A549 and Calu-1 cells. We then verified that there was a protein interaction between SEC14L2 and SCARB1.ConclusionSEC14L2 promoted cholesterol uptake in NSCLC cells by up-regulating SCARB1 expression, thereby promoting NSCLC development.

Encapsulation and Delivery of the Kinase Inhibitor PIK-75 by Organic Core High-Density Lipoprotein-Like Nanoparticles Targeting Scavenger Receptor Class B Type 1.

PIK-75 (F7) is a potent multikinase inhibitor that targets p110α, DNA-PK, and p38γ. PIK-75 has shown potential as a therapy in preclinical cancer models, but it has not been used in the clinic, at least in part, due to limited solubility. We therefore developed a nanoparticle to encapsulate PIK-75 and enable targeted cellular delivery. Scavenger receptor class B type 1 (SR-B1) is often overexpressed in cancer compared with normal cells, which enables targeting by synthetic lipid nanoparticles with some features of native high-density lipoprotein (HDL), the natural ligand of SR-B1. We investigated the use of organic core (oc) molecular platforms to synthesize HDL-like nanoparticles (oc-HDL NP). Employing an oc, we successfully formulated PIK-75 into oc-HDL NPs. The PIK-75 loaded oc-HDL NP (PIK-75 oc-HDL NP), comprising ∼20 PIK-75 molecules/NP, has similar size, surface charge, and surface composition as oc-HDL NP and natural human HDL. Using prostate cancer (PCa) and cutaneous T-cell lymphoma (CTCL) models known to be sensitive to inhibitors of p110α and p38γ, respectively, we found that PIK-75 oc-HDL NPs specifically targeted SR-B1 to deliver PIK-75 and potently induced cell death in vitro in PCa and CTCL and in vivo in a murine PCa model. Additionally, we found that PIK-75 oc-HDL NP, but not free PIK-75 or oc-HDL NP alone, reduced the IC50 in the NCI-60 cell line panel and additional pancreatic cancer cell lines. These data demonstrate the first example of drug-loaded oc-HDL NP that actively target SR-B1 and kill cancer cells in vitro and in vivo, encouraging further development and translation to human patients.

In silico studies of designed thiadiazole derivatives as retinoic acid receptor-alpha (RAR-α) inhibitors for potential contraceptive application.

Retinoic acid receptors (RARs) are a class of nuclear receptors that play an important role in spermatogenesis. Blocking RAR-α activity is an effective method of contraception. In this study, we used in silico methods to design and evaluate new thiadiazole-based RAR-α antagonists. We performed molecular docking, ADME studies, molecular dynamics, and Binding free energy calculations to determine binding affinities, oral bioavailability, and stability. From the twenty designed compounds, three compounds, BVSSS14, BVSSS09, and BVSSS10, exhibit promising interactions and docking scores of -12.3, -11.6, and -10.1 kcal/mol, respectively. Using molecular dynamics simulations, we elucidated the conformational stability of these three compounds within the RAR-α binding pocket. Furthermore, MMGBSA analysis provided insights into binding free energies, proving the efficacy of BVSSS14, BVSSS09, and BVSSS10. In silico approach highlights the potential of BVSSS14, BVSSS09, and BVSSS10 as promising compounds to inhibit RAR-α, and these compounds are effective candidates as contraceptive agents, laying the groundwork for future experimental validation.

Intracellular pocket conformations determine signaling efficacy through the opioid receptor.

It has been challenging to determine how a ligand that binds to a receptor activates downstream signaling pathways and to predict the strength of signaling. The challenge is compounded by functional selectivity, in which a single ligand binding to a single receptor can activate multiple signaling pathways at different levels. Spectroscopic studies show that in the largest class of cell surface receptors, 7 transmembrane receptors (7TMRs), activation is associated with ligand-induced shifts in the equilibria of intracellular pocket conformations in the absence of transducer proteins. We hypothesized that signaling through the opioid receptor, a prototypical 7TMR, is linearly proportional to the equilibrium probability of observing intracellular pocket conformations in the receptor-ligand complex. Here we show that a machine learning model based on this hypothesis accurately calculates the efficacy of both G protein and -arrestin-2 signaling. Structural features that the model associates with activation are intracellular pocket expansion, toggle switch rotation, and sodium binding pocket collapse. Distinct pathways are activated by different arrangements of the ligand and sodium binding pockets and the intracellular pocket. While recent work has categorized ligands as active or inactive (or partially active) based on binding affinities to two conformations, our approach accurately computes signaling efficacy along multiple pathways.

Supportive care in myeloma-when treating the clone alone is not enough.

The overall survival in patients with multiple myeloma has increased over recent decades. This trend is anticipated to further advance with the emergence of T-cell-redirecting therapies, including chimeric antigen receptor T-cell (CAR T) therapy and T-cell-engaging bispecific antibodies. Despite these therapeutic improvements, treatment-related adverse events impede quality of life. This underscores the imperative of optimizing supportive care strategies to maximize treatment outcomes. Such optimization is crucial not only for patient well-being but also for treatment adherence, which may translate into long-term disease control. We here describe a) how to prevent bone disease, b) a risk-adapted thrombosis prophylaxis approach, c) the management of on-target, off-tumor toxicity of G-protein-coupled receptor class C group 5 member D-targeting T-cell-redirecting therapies, and d) infectious prophylaxis, with a focus on infections during T-cell-redirecting therapies.

Phase I Trial of MCARH109, a G Protein-Coupled Receptor Class C Group 5 Member D (GPRC5D)-Targeted Chimeric Antigen Receptor T-Cell Therapy for Multiple Myeloma: An Updated Analysis.

MCARH109 is a first-in-class G protein-coupled receptor, class C, group 5, member D (GPRC5D)-targeted chimeric antigen receptor (CAR) T-cell therapy for patients with relapsed/refractory multiple myeloma. This phase I clinical trial included 17 patients and determined that MCARH109 is safe at a maximum tolerated dose of 150 × 106 CAR T cells. In this updated analysis, no new serious adverse events were reported at a median follow-up of 37 months. Overall, 12 (71%) of 17 patients responded, including seven (70%) of 10 patients previously treated with B-cell maturation antigen-targeted therapy. The median duration of response was 8.6 months (95% CI, 5.7 to not reached [NR]) with two patients sustaining a stringent complete response at the time of last follow-up, 32 months and 41 months, respectively. The median overall survival (OS) was NR and the 3-year OS estimate was 59% (95% CI, 40 to 88). Possible GPRC5D loss via immunohistochemistry was observed in 6 (60%) of 10 patients at relapse. High-dimensional spectral cytometry-based immune profiling associated an activated T-cell phenotype at apheresis with a response to MCARH109.

CAR T-cell therapy to treat multiple myeloma: current state and future directions.

Chimeric antigen receptor (CAR) T-cell therapy represents a transformative advancement in treating relapsed or refractory multiple myeloma (MM) in both early- and late-line settings. MM, a plasma cell malignancy, traditionally requires ongoing complex drug regimens, posing significant burdens on patients. In contrast, CAR T-cell therapy offers a one-time treatment option without the need for continuous maintenance therapy. CAR T-cell therapy leverages engineered T-cells to target specific antigens on tumor cells, leading to their elimination. Current approved therapies target B-cell maturation antigen (BCMA); new targets are under investigation, such as G-protein-coupled receptor class C group 5 member D (GPRC5D). Despite its efficacy, CAR T-cell therapy is associated with serious toxicities such as cytokine release syndrome (CRS) and immune-effector cell-associated neurotoxicity syndrome (ICANS), necessitating careful management. The review will provide an overview of the design and manufacturing of CAR T-cells and current FDA indications, as well as challenges and future directions of CAR-T therapy for MM treatment.

Exploring TAS2R46 biomechanics through molecular dynamics and network analysis.

Understanding the intricate interplay between structural features and signal-processing events is crucial for unravelling the mechanisms of biomolecular systems. G protein-coupled receptors (GPCRs), a pervasive protein family in humans, serve a wide spectrum of vital functions. TAS2Rs, a subfamily of GPCRs, play a primary role in recognizing bitter molecules and triggering events leading to the perception of bitterness, a crucial defence mechanism against spoiled or poisonous food. Beyond taste, TAS2Rs function is associated with many diseases as they are expressed in several extra-oral tissues. Given that the precise functioning mechanisms of TAS2R remain poorly understood, this study employed molecular dynamics simulations combined with network-based analysis to investigate local conformational changes and global structural correlations in different states of the receptor. The focus was on the human TAS2R46 bitter taste receptor, recently resolved experimentally, both in the presence and absence of strychnine, a known bitter agonist. The results showed that the ligand-bound state of the receptor exhibited more correlated dynamics compared to the apo state, and the presence of the agonist mediated the allosteric network between two helices (TM3 and TM6) which mainly convey the signal transferring from the extracellular to the intracellular region. By elucidating the hallmarks of the conformational changes and allosteric network of TAS2R46 under varying conditions, this study has enabled the identification of the unique structural and dynamics features of this receptor, thereby establishing a foundation for a more profound characterisation of this intriguing class of receptors.

Nanoparticle-Directed Antioxidant Therapy Can Ameliorate Disease Progression in a Novel, Diet-Inducible Model of Coronary Artery Disease.

Oxidative stress plays a crucial role in the pathogenesis of coronary artery disease. In cardiovascular research using murine models, the generation and maintenance of models with robust coronary arterial atherosclerosis has been challenging. We characterized a new mouse model in which the last 3 amino acids of the carboxyl terminus of the HDL (high-density lipoprotein) receptor (SR-B1 [scavenger receptor, class B, type 1]) were deleted in a low-density lipoprotein receptor knockout (LDLR-/-) mouse model (SR-B1ΔCT/LDLR-/-) fed an atherogenic diet. We also tested the therapeutic effects of an oxidative stress-targeted nanoparticle in atherogenic diet-fed SR-B1ΔCT/LDLR-/- mice. The SR-B1ΔCT/LDLR-/- mice fed an atherogenic diet had occlusive coronary artery atherosclerosis, impaired cardiac function, and a dramatically lower survival rate, compared with LDLR-/- mice fed the same diet. As SR-B1ΔCT/LDLR-/- mice do not exhibit female infertility or low pup yield, they are far easier and less costly to use than the previously described SR-B1-based models of coronary artery disease. We found that treatment with the targeted nanoparticles improved the cardiac functions and corrected hematologic abnormalities caused by the atherogenic diet in SR-B1ΔCT/LDLR-/- mice but did not alter the distinctive plasma lipid levels. The SR-B1ΔCT/LDLR-/- mice developed diet-inducible, fatal atherosclerotic coronary artery disease, which could be ameliorated by targeted nanoparticle therapy. Our study provides new tools for the development of cardiovascular therapies.

Mechanism of chrysophanol in inhibiting ox-LDL-induced macrophage foaminess through NF-κB/HMGB1-PI3K/Akt/mTOR pathway

The aim of this study was to investigate the underlying mechanism of chrysophanol(Chr) in reducing inflammation and foam cell formation induced by oxidized low-density lipoprotein(ox-LDL) and to investigate the targets and pathways related to effects of Chr on coronary atherosclerosis, providing a theoretical basis for the development of new clinical drugs. RAW264.7 macrophages were cultured in vitro, and after determining the appropriate concentrations of Chr and ox-LDL for treating RAW264.7 macrophages using a cell counting kit-8(CCK-8), the macrophages were treated with different concentrations of Chr(10, 15 μmol·L~(-1)) and ox-LDL(with or without 80 mg·mL~(-1)) for 24 h. RAW264.7 macrophages were divided into four groups: control group, model group(80 mg·mL~(-1) ox-LDL), treatment group(80 mg·mL~(-1) ox-LDL+10 μmol·L~(-1) Chr), and treatment group(80 mg·mL~(-1) ox-LDL+15 μmol·L~(-1) Chr). Lipid accumulation in each group was detected by oil red O staining. CD36 expression was analyzed by flow cytometry. Western blot was used to detect the expression of scavenger receptor class A1(SR-A1), scavenger receptor class B type Ⅰ(SR-B1), autophagy-related protein 5(Atg5), Beclin-1, autophagy adaptor protein p62(P62), the ratio of microtubule-associated protein light chain 3(LC3)Ⅱ to LC3Ⅰ(LC3Ⅱ/LC3Ⅰ), nuclear factor kappa B P65(NF-κB P65), inhibitor of κB kinase β(IKKβ), nuclear factor of κB inhibitor(IκB), high mobility group box protein 1(HMGB1), phosphatidylinositol 3-kinase(PI3K), protein kinase B(Akt), and phosphorylated mammalian target of rapamycin(mTOR). Real-time quantitative polymerase chain reaction(RT-qPCR) was used to detect the mRNA expression levels of ATP-binding cassette transporter A1(ABCA1), ATP-binding cassette transporter G1(ABCG1), interleukin-1β(IL-1β), tumor necrosis factor-α(TNF-α), HMGB1, inducible nitric oxide synthase(iNOS), arginase 1(Arg1), macrophage galactose-type lectin-1(Mgl-1), and NF-κB P65. Immunofluorescence analysis was performed to determine the localization of HMGB1 in RAW264.7 cells in each group. The autophagy inhibitor 3-methyladenine(3-MA) was added as a control for reverse validation, and the RAW264.7 macrophages were divided into four groups again: control group, model group(80 mg·mL~(-1) ox-LDL), treatment group(80 mg·mL~(-1) ox-LDL + 15 μmol·L~(-1) Chr), and inhibitor group(80 mg·mL~(-1) ox-LDL+15 μmol·L~(-1) Chr+3-MA). The results showed that Chr effectively reduced foam cell formation by regulating the expression levels of SR-A1, ABCA1, ABCG1, the LC3Ⅱ/LC3Ⅰ ratio, Atg5, Beclin-1, and p62, and inhibited the NF-κB/HMGB1-PI3K/Akt/mTOR signaling pathway. Moreover, the inhibitory effects of Chr on autophagy and the NF-κB/HMGB1-PI3K/Akt/mTOR pathway were reversed by the autophagy inhibitor 3-MA. In conclusion, Chr exhibits therapeutic potential for the treatment of atherosclerosis by inducing autophagy and modulating the NF-κB/HMGB1 and PI3K/Akt/mTOR pathways to inhibit the formation of macrophage inflammatory foam cells.

Cellular uptake of CPX-351 by scavenger receptor class B type 1-mediated nonendocytic pathway

The proper uptake of drugs in liposome formulations into target cells markedly impacts therapeutic efficacy. The protein corona (PC), formed by the adsorption of serum proteins onto the liposome surface, binds to specific surface receptors of target cells, influencing the uptake pathway. We investigated the uptake pathway into leukemia cells based on PC analysis of CPX-351, a liposome containing cytarabine and daunorubicin in a fixed 5:1 synergistic molar ratio. The PC of CPX-351 mixed with fetal bovine serum was analyzed by nanoflow liquid chromatography-tandem mass spectrometry. CPX-351 uptake in HL-60, K562, and THP-1 leukemia cell lines, was measured by flow cytometry using daunorubicin fluorescence. The major components of CPX-351 PC were apolipoproteins A-I and A-II, which bind to scavenger receptor class B type 1 (SR-BI), a nonendocytic pathway that takes up only liposome contents. SR-BI was expressed in each cell, and its expression correlated with CPX-351 uptake. The uptake was significantly decreased by the inhibition of clathrin-mediated endocytosis and macropinocytosis. Additionally, blocks lipid transport-1 (BLT-1), a selective inhibitor of SR-BI, decreased the uptake; however, high-dose BLT-1 addition significantly increased the uptake, which was more strongly inhibited by macropinocytosis suppression compared with clathrin-mediated endocytosis. BLT-1 enhances the binding of SR-BI to liposomes in a dose-dependent manner. These findings indicate that the enhancement of binding between SR-BI and CPX-351 activates different pathways, such as macropinocytosis, distinct from CPX-351 alone. SR-BI may be a biomarker for CPX-351 therapy, and the combination of CPX-351 with high-dose BLT-1 may augment therapeutic efficacy.

The membrane domains of mammalian adenylyl cyclases are lipid receptors.

The biosynthesis of cyclic 3',5'-adenosine monophosphate (cAMP) by mammalian membrane-bound adenylyl cyclases (mACs) is predominantly regulated by G-protein-coupled receptors (GPCRs). Up to now the two hexahelical transmembrane domains of mACs were considered to fix the enzyme to membranes. Here, we show that the transmembrane domains serve in addition as signal receptors and transmitters of lipid signals that control Gsα-stimulated mAC activities. We identify aliphatic fatty acids and anandamide as receptor ligands of mAC isoforms 1-7 and 9. The ligands enhance (mAC isoforms 2, 3, 7, and 9) or attenuate (isoforms 1, 4, 5, and 6) Gsα-stimulated mAC activities in vitro and in vivo. Substitution of the stimulatory membrane receptor of mAC3 by the inhibitory receptor of mAC5 results in a ligand inhibited mAC5-mAC3 chimera. Thus, we discovered a new class of membrane receptors in which two signaling modalities are at a crossing, direct tonic lipid and indirect phasic GPCR-Gsα signaling regulating the biosynthesis of cAMP.

The novel ECM protein SNED1 mediates cell adhesion via the RGD-binding integrins α5β1 and αvβ3.

The extracellular matrix (ECM) is a complex meshwork comprising over 100 proteins. It serves as an adhesive substrate for cells and, hence, plays critical roles in health and disease. We have recently identified a novel ECM protein, SNED1, and have found that it is required for neural crest cell migration and craniofacial morphogenesis during development and in breast cancer, where it is necessary for the metastatic dissemination of tumor cells. Interestingly, both processes involve the dynamic remodeling of cell-ECM adhesions via cell surface receptors. Sequence analysis revealed that SNED1 contains two amino acid motifs, RGD and LDV, known to bind integrins, the largest class of ECM receptors. We thus sought to investigate the role of SNED1 in cell adhesion. Here, we report that SNED1 mediates breast cancer and neural crest cell adhesion via its RGD motif. We further demonstrate that cell adhesion to SNED1 is mediated by the RGD integrins α5β1 and αvβ3. These findings are a first step toward identifying the signaling pathways activated downstream of the SNED1-integrin interactions guiding craniofacial morphogenesis and breast cancer metastasis.

Tailored charge-neutral self-assembled L2Zn2 container for taming oxalate.

Dicarboxylic acids and their derivatives play crucial roles in various biological processes, necessitating the development of effective receptors for their detection. In particular, the smallest dicarboxylate, oxalate, presents a significant importance due to its widespread presence in nature and its association with various diseases. Yet, very little attention was devoted to the recognition of oxalate with metal-driven self-assemblies like cages or containers while numerous classic organic receptors for oxalate exist. This discrepancy is astonishing because metallocontainers or metallocages have advantages over classic macrocycles or organocages like a higher modularity and good preorganization paired with a ready receptor preparation by metal complexation. The reason for the underrepresentation is the competitive nature and excellent ligand properties of oxalate which not only is associated with the aforementioned diseases but also poses a serious hazard for metal-driven self-assemblies because the dianion can easily replace ligand strands leading to a partial or full receptor decomposition. Herein, we present a charge-neutral zinc(II)-based metallocontainer which was tuned to contest oxalate as most competitive dicarboxylate. The dianion is bound in a 1:1 fashion with a binding constant of log K = 4.39 selectively over other dicarboxylates by maintaining the receptor stability. This study highlights the importance of a highly modular receptor design so that tailored hosts can be designed to tackle the recognition of challenging competitive analytes.

Targeting CD36 With EP 80317 Reduces Remote Inflammatory Response to Hind Limb Ischemia-Reperfusion in Mice.

Reperfusion of ischemic skeletal muscle triggers oxidative stress and an immediate inflammatory reaction, leading to damage of distant organs such as the lungs. The inflammatory process implicates numerous mediators, including cytokines, chemokines, and arachidonic acid metabolites. In the orchestration of the inflammatory cascade, a critical role is played by the cluster of differentiation-36 receptor (CD36), a scavenger receptor class B protein (SR-B2) which is expressed on macrophages and functions as a Toll-like receptor coreceptor. A mouse model of hind limb ischemia-reperfusion has been used to investigate the interplay between CD36 signaling and remote inflammation: leukocyte recruitment, regulation of the nucleotide-binding domain leucin-rich repeat and pyrin-containing receptor 3 (NLRP3) inflammasome, and release of nuclear factor-kappa B (NF-ĸB) and arachidonic acid metabolites. Levels of reactive oxygen species, inflammatory mediators, and gene expression were measured in blood and lung tissue samples collected from anesthetized mice on which unilateral hind limb ischemia was induced by rubber band constriction for 30 min followed by reperfusion for 3 h. The CD36 modulator EP 80317, a member of the growth hormone releasing peptide 6 family, was employed as a pharmacological agent to mitigate distant lung injury following skeletal limb ischemia-reperfusion. Targeting CD36 on monocytes/macrophages, EP 80317 abated pro-inflammatory signaling and transcriptional activity encompassing lipid and cytokine mediators. Targeting CD36 was shown to offer promise for curtailing tissue injury following hind limb ischemia-reperfusion.