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The insulin and dopaminergic systems in the brain are associated with schizophrenia and Parkinson's disease with respect to etiology and treatment. The present study investigated the crosstalk between the insulin receptor (IR) and dopamine receptor and found that insulin stimulation selectively inhibits signaling of D3R in a PKCβII‐dependent manner. Upon insulin stimulation, E3 ligase enzyme Mdm2 moves out of the nucleus to ubiquitinate PKCβII. Subsequently, ubiquitinated PKCβII translocates to the cell membrane and interacts with D3R in a phosphorylation‐dependent manner at S229/257, resulting in the attenuation of D3R signaling and initiating clathrin‐mediated endocytosis and downregulation. Considering that both IR and D3R are closely related to some neuropsychosis, this study could provide new molecular insight into the etiology of the disorder. [ABSTRACT FROM AUTHOR]

Dopamine D2 receptor (D2R) has been shown to activate extracellular signal‐regulated kinases (ERKs) via distinct pathways dependent on either G‐protein or β‐arrestin. However, there has not been a systematic study of the regulatory process of D2R‐mediated ERKs activation by G protein‐ versus β‐arrestin‐dependent signaling since D2R stimulation of ERKs reflects the simultaneous action of both pathways. Here, we investigated that differential regulation of D2R‐mediated ERKs activation via these two pathways. Our results showed that G protein‐dependent ERKs activation was transient, rapid, reached maximum level at around 2 min, and importantly, the activated ERKs were entirely confined to the cytoplasm. In contrast, β‐arrestin‐dependent ERKs activation was more sustained, slower, reached maximum level at around 10 min, and phosphorylated ERKs translocated into the nucleus. Src was found to be commonly involved in both the G protein‐ and β‐arrestin‐dependent pathway‐mediated ERKs activation. Pertussis toxin Gi/o inhibitor, GRK2‐CT, AG1478 epidermal growth factor receptor inhibitor, and wortmannin phosphoinositide 3‐kinase inhibitor all blocked G protein‐dependent ERKs activation. In contrast, GRK2 and β‐Arr2 played a main role in β‐arrestin‐dependent ERKs activation. Receptor endocytosis showed minimal effect on the activation of ERKs mediated by both pathways. Furthermore, we found that the formation of a complex composed of phospho‐ERKs, β‐Arr2, and importinβ1 promoted the nuclear translocation of activated ERKs. The differential regulation of various cellular components, as well as temporal and spatial patterns of ERKs activation via these two pathways, suggest the existence of distinct physiological outcomes. [ABSTRACT FROM AUTHOR]

Objectives: To explore the effect of recombinant LZ‐8 (rLZ‐8) on streptozocin (STZ)‐induced diabetic rats and further illustrate its underlying mechanism. Methods: Rats were intraperitoneally injected with single‐dose STZ 50 mg/kg for induction of type 1 diabetes (T1D), and then, the diabetic rats were treated with rLZ‐8 for 3 months. The clinical symptoms, fasting blood glucose, insulin, cytokines, histopathology, flow cytometry and immunofluorescence were used to evaluate the therapeutic effect and underlying mechanism of rLZ‐8 on alleviating diabetes mellitus (DM). Key findings: Treatment with rLZ‐8 obviously alleviated the clinical symptoms of T1D and dose‐dependently reduced the levels of blood glucose, blood lipid and haemoglobin A1c (HbA1c) in diabetic rat model. Meanwhile, rLZ‐8 markedly increased insulin secretion and protected against STZ‐induced pancreatic tissue injury. Additionally, rLZ‐8 dramatically inhibited the levels of TNF‐α and IL‐1β, and obviously increased the level of IL‐10 in serum and pancreas. Further investigation indicated that rLZ‐8 treatment significantly increased the number of regulatory T cells (Tregs) and up‐regulated the expression of Foxp3 to restore balance between anti‐inflammatory and inflammatory cytokines. Conclusions: These data suggest that rLZ‐8 can antagonize STZ‐induced T1D, and its mechanism may be related to inhibit inflammation and enhance Tregs generation. [ABSTRACT FROM AUTHOR]

Graphical abstract Abstract We describe herein the design, synthesis, and biological evaluation of a series of novel protein tyrosine phosphatase 1B (PTP1B) inhibitor retrochalcones having an allyl chain at the C-5 position of their B ring. Biological screening results showed that the majority of these compounds exhibited an inhibitory activity against PTP1B. Thus, preliminary structure-activity relationship (SAR) and quantitative SAR analyses were conducted. Among the compounds, 23 was the most potent inhibitor, exhibiting the highest in vitro inhibitory activity against PTP1B with an IC 50 of 0.57 µM. Moreover, it displayed a significant hepatoprotective property via activation of the IR pathway in type 2 diabetic db/db mice. In addition, the results of our docking study showed that 23, as a specific inhibitor of PTP1B, effectively transformed the WPD loop from "close" to "open" in the active site. These results may reveal suitable compounds for the development of PTP1B inhibitors. [ABSTRACT FROM AUTHOR]

In this study, we aimed to demonstrate the antidiabetic potential of (E)-N-(4-(3-(5-bromo-4-hydroxy-2-methoxyphenyl)acryloyl) phenyl)-4- tert -butylbenzamide (SN158) through peroxisome proliferator-activated receptor (PPAR)-α/γ dual activation. SN158 interacted with both PPARα and PPARγ, and increased their transcriptional activities. Simultaneously, SN158 treatment led to an increase in adipogenic differentiation of 3T3-L1 preadipocytes and fatty acid oxidation in hepatocytes. In addition, glucose uptake in myotubes was significantly increased by SN158 treatment. Finally, SN158 significantly lowered the plasma levels of glucose, triglycerides, and free fatty acids in ob/ob mice without severe weight gain and hepatomegaly. These results suggest that SN158 can be useful as a potential therapeutic agent against type 2 diabetes and related metabolic disorders by alleviating glucose and lipid abnormalities. [ABSTRACT FROM AUTHOR]

We here demonstrate that ( E)-1-(3-aminophenyl)-3-(5-bromo-4-hydroxy-2-methoxyphenyl)prop-2-en-1-one ( SN159) is a novel peroxisome proliferator-activated receptor ( PPAR) partial agonist that improves insulin sensitivity. SN159 interacted directly with PPARα and PPARγ, which were confirmed by LanthaScreen ligand binding assay and molecular docking study. SN159 treatment leads to a significant improvement of insulin sensitivity, resulting in enhancing glucose uptake in muscle cells. SN159 stimulated adipogenic differentiation of 3T3-L1 preadipocytes, however, the effects were much weaker than those of PPARγ agonist troglitazone. In parallel, SN159 increased weakly the transcriptional activities of PPARα/γ, compared to the positive control. Furthermore, PPARγ activation and adipogenic differentiation by troglitazone were significantly reduced by treatment with SN159, indicating that SN159 is a partial agonist of PPARs. SN159 was able to enhance fatty acid oxidation and glucose utilization through the dual activation of PPARα/γ. Taken together, these results suggest that SN159 is a novel PPAR partial agonist, which can be used as potential therapeutic agents against type 2 diabetes and related metabolic disorders by enhancing glucose and lipid metabolism. [ABSTRACT FROM AUTHOR]

• Lico E improved insulin sensitivity by suppressing NLPR3 in IR HepG2. • Lico E suppressed ROS generation, TNF-α, IL-1β & IL-18 production in IR HepG2. • Lico E suppressed G6pase and PEPCK gene expression and increased Glut4 level in IR HepG2. Our previous research demonstrated that compound licochalcone E can reduce glucose tolerance and lipid metabolism in diabetic rats, although its mechanism remains unknown. Here, we used palmitic acid (PA) to establish a PA-treated HepG2 model, and then examined glucose uptake, glucose consumption, and blood lipids to evaluate the effects of licochalcone E within the safe dose range in the model. Polymerase chain reaction (PCR) was used to detect the expression levels of key genes associated with liver gluconeogenesis; enzyme-linked immunosorbent assay (ELISA) was deployed to evaluate the concentration of inflammatory factors; and laser confocal microscopy and western blot were used to determine the levels of reactive oxygen species (ROS) and NLRP3 inflammasome signaling pathway-related proteins, respectively. Finally, molecular simulations were exploited to validate the interaction between licochalcone E and the NLRP3 inflammasome. The results demonstrated that licochalcone E showed no toxicity in the dose range of 2.5–40 μM. In this dose range, licochalcone E substantially increased the uptake and consumption of glucose in the insulin resistance model and dose-dependently reduced the concentration of total cholesterol. The PCR results indicated that licochalcone E dose-dependently reduced the expression of Glucose-6-phosphatase (G6Pase) and Phosphoenolpyruvate carboxykinase (PEPCK) genes and increased the expression of Glucose Transporter 4 (Glut4) in PA-treated HepG2. Moreover, the ELISA results revealed that licochalcone E significantly reduced the expression of TNF-α, IL-1β, and IL-18. Confocal microscopy results showed that licochalcone E dramatically reduced the generation of ROS and the expressions of NLRP3 and its downstream caspase-1 in PA-treated HepG2 model. Western blot results further indicated that licochalcone E significantly reduced the expression of NLRP3, caspase-1 and IL-1β in the model. Additionally, molecular simulations demonstrated that licochalcone E has good binding affinity for the NLPR3 inflammasome. We concluded that licochalcone E has the potential to be used as an insulin sensitizer by reducing the release of ROS and inflammatory factors following inhibition of the NLPR3 signaling pathway. [ABSTRACT FROM AUTHOR]

The insulin and dopaminergic systems in the brain are associated with schizophrenia and Parkinson's disease with respect to etiology and treatment. The present study investigated the crosstalk between the insulin receptor (IR) and dopamine receptor and found that insulin stimulation selectively inhibits signaling of D 3 R in a PKCβII-dependent manner. Upon insulin stimulation, E3 ligase enzyme Mdm2 moves out of the nucleus to ubiquitinate PKCβII. Subsequently, ubiquitinated PKCβII translocates to the cell membrane and interacts with D 3 R in a phosphorylation-dependent manner at S229/257, resulting in the attenuation of D 3 R signaling and initiating clathrin-mediated endocytosis and downregulation. Considering that both IR and D 3 R are closely related to some neuropsychosis, this study could provide new molecular insight into the etiology of the disorder., (© 2024 Federation of European Biochemical Societies.)

Dopamine D 2 receptor (D 2 R) has been shown to activate extracellular signal-regulated kinases (ERKs) via distinct pathways dependent on either G-protein or β-arrestin. However, there has not been a systematic study of the regulatory process of D 2 R-mediated ERKs activation by G protein- versus β-arrestin-dependent signaling since D 2 R stimulation of ERKs reflects the simultaneous action of both pathways. Here, we investigated that differential regulation of D 2 R-mediated ERKs activation via these two pathways. Our results showed that G protein-dependent ERKs activation was transient, rapid, reached maximum level at around 2 min, and importantly, the activated ERKs were entirely confined to the cytoplasm. In contrast, β-arrestin-dependent ERKs activation was more sustained, slower, reached maximum level at around 10 min, and phosphorylated ERKs translocated into the nucleus. Src was found to be commonly involved in both the G protein- and β-arrestin-dependent pathway-mediated ERKs activation. Pertussis toxin Gi/o inhibitor, GRK2-CT, AG1478 epidermal growth factor receptor inhibitor, and wortmannin phosphoinositide 3-kinase inhibitor all blocked G protein-dependent ERKs activation. In contrast, GRK2 and β-Arr2 played a main role in β-arrestin-dependent ERKs activation. Receptor endocytosis showed minimal effect on the activation of ERKs mediated by both pathways. Furthermore, we found that the formation of a complex composed of phospho-ERKs, β-Arr2, and importinβ1 promoted the nuclear translocation of activated ERKs. The differential regulation of various cellular components, as well as temporal and spatial patterns of ERKs activation via these two pathways, suggest the existence of distinct physiological outcomes., (© 2023 Federation of European Biochemical Societies.)

Acute lung injury (ALI) is an inflammatory condition and there are no effective treatments. A novel new compound----colchicine-myricetin hybrid (CMyrH) was herein designed and synthesized. To evaluate the activity of CMyrH in ALI, we used a bleomycin (BLM) induced BEAS-2B injury model in vitro and established a well-recognized rat model of BLM-induced lung injury in vivo . The results demonstrated that colchicine-myricetin hybrid protected BEAS-2B cells against BLM-induced cell injury in an increased dose manner, and reduced wet/dry weight ratio, histological scoring, and inflammation cytokines IL-1β, IL-6, IL-18, and TNF-α levels of lung tissue of the rats. Furthermore, we found colchicine-myricetin hybrid inhibited caspase-1, ASC, GSDMD, and NLRP-3 expression in vivo . Meanwhile, we used molecular docking to analyze the binding mode of colchicine-myricetin hybrid and human neutrophil elastase (HNE), it revealed that colchicine-myricetin hybrid showed strong binding affinity toward human neutrophil elastase when compared to its parent molecules. In conclusion, It is suggested that colchicine-myricetin hybrid antagonized acute lung injury by focusing on multi-targets via multi-mechanisms, and might be served as a potential therapeutic agent for acute lung injury., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 Li, Yan, Wei, Pu, Zhu, Cao, Liu, Liu, Li, Li, Li and Wu.)

Colchicine is a bioactive alkaloid originally from Colchicum autumnale and possesses excellent antiproliferative activity. However, colchicine-associated severe toxicity, gastrointestinal side effects in particular, limits its further therapeutic use. In the current study, we thus designed and synthesized a novel hybrid (CMH) by splicing colchicine and magnolol, a multifunctional polyphenol showing favorable gastrointestinal protection. The antitumor activity of CMH in Lewis lung carcinoma (LLC) was then evaluated in vitro and in vivo . Biologically, CMH inhibited the growth of LLC cells with an IC 50 of 0.26 μM, 100 times more potently than cisplatin (26.05 μM) did. Meanwhile, the cytotoxicity of CMH was 10-fold lower than that of colchicine in normal human lung cells (BEAS-2B). In C57BL/6 mice xenograft model, CMH (0.5 mg/kg) worked as efficacious as colchicine (0.5 mg/kg) to inhibit tumor growth and 2 times more potently than cisplatin (1 mg/kg). In terms of mortality, 7 out of 10 mice died in colchicine group (0.75 mg/kg), while no death was observed in groups receiving CMH or cisplatin at 0.75 mg/kg. Mechanistic studies using Western blot revealed that CMH dose-dependently suppressed the protein expression of phosphorylated ERK. Molecular docking analysis further indicated that CMH was well fitted in the colchicine binding site of tubulin and formed several hydrogen bonds with tubulin protein. These results enable our novel hybrid CMH as a potential antineoplastic agent with lower toxicity, and provide perquisites for further investigation to confirm the therapeutic potentiality of this novel hybrid., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. The handling editor FH declared a shared affiliation with the author KC at the time of review., (Copyright © 2022 Li, Hu, Pu, Li, Zhu, Cao, Li, Ma, Liu, Li, Liu, Chen and Wu.)

[This corrects the article DOI: 10.1039/C8MD00237A.].

The dopamine D 3 receptor (D 3 R) is a proven therapeutic target for the treatment of neurological and neuropsychiatric disorders. In particular, D 3 R-selective ligands that can eliminate side effects associated with dopamine D 2 receptor (D 2 R) therapeutics have been validated. However, the high homology in signaling pathways and the sequence similarity between D 2 R and D 3 R have rendered the development of D 3 R-selective ligands challenging. Herein, we designed and synthesized a series of piperazine-phthalimide bitopic ligands based on a fragment-based and molecular docking inspired design. Compound 9i was identified as the most selective D 3 R ligand among these bitopic ligands. Its selectivity was improved compared to reference compounds 1 and 2 by 9- and 2-fold, respectively, and it was 21-fold more potent than compound 2 . Molecular docking demonstrated that the orientation of Leu 2.64 and Phe 7.39 and the packing at the junction of helices may affect the specificity for D 3 R over D 2 R. Functional evaluation revealed that D 3 R-selective ligand 9i displayed a subpicomolar agonist activity at D 3 R with a 199-fold increase in potency compared to quinpirole. These results may be useful for the fragment-based design of bitopic compounds as selective D 3 R ligands.