Animals ; Arrestins ; metabolism ; Hypoxia ; metabolism ; Male ; Prefrontal Cortex ; metabolism ; Rats ; Rats, Sprague-Dawley ; Receptors, G-Protein-Coupled ; metabolism ; beta-Arrestin 1 ; beta-Arrestins

Besides its role in desensitization and internalization of receptors, β-arrestin2 facilitates G protein-independent signaling through its ability to scaffold various signaling molecules. β-arrestin2 is widely distributed in the central nervous system, and mediates signal transduction of brain circuit. The aim of the present study was to investigate the role of β-arrestin2 in reward behaviors induced by cocaine. We assessed the conditioned place preference (CPP) induced by low (10 mg/kg), moderate (20 mg/kg) and high (30 mg/kg) doses of cocaine in Arrb2(-/-) mice and Arrb2(+/+) controls. In the Arrb2(-/-) mice, moderate and high, but not low, dose of cocaine induced pronounced increases of CPP scores, which were higher than those in the Arrb2(+/+) mice. Moreover, cocaine-induced locomotor activity was significantly lower in Arrb2(-/-) mice than that of Arrb2(+/+) littermate controls. Taken together, our results suggest a potential role of β-arrestin2 in the cocaine-induced rewarding behaviors.
Animals ; Arrestins ; physiology ; Behavior, Animal ; drug effects ; Cocaine ; pharmacology ; Mice ; Mice, Knockout ; Motor Activity ; drug effects ; Reward ; beta-Arrestin 2 ; beta-Arrestins

Parkinson's disease is the second most common neurodegenerative disease in the world. Beta-arrestin-2 has been reported to be an important protein involved in D(2) dopamine receptor desensitization, which is essential to Parkinson's disease. Moreover, the potential value of pharmacological inactivation of G protein-coupled receptor kinase or arrestin in the treatment of patients with Parkinson's disease has recently been shown. We studied the interaction between D(2) dopamine receptor and beta-arrestin-2 and the pharmacological regulation of chemical compounds on such interaction using capillary zone electrophoresis. The results from screening more than 40 compounds revealed three compounds that remarkably inhibit the beta-arrestin-2/D(2) dopamine receptor interaction among them. These compounds are promising therapies for Parkinson's disease, and the method used in this study has great potential for application in large-scale drug screening and evaluation.
Arrestins ; antagonists & inhibitors ; metabolism ; Dopamine ; metabolism ; Dopamine Antagonists ; therapeutic use ; Dopamine D2 Receptor Antagonists ; Drug Evaluation, Preclinical ; Electrophoresis, Capillary ; Humans ; Parkinson Disease ; drug therapy ; metabolism ; pathology ; Receptors, Dopamine D2 ; metabolism ; Signal Transduction ; beta-Arrestin 2 ; beta-Arrestins

G protein-coupled receptors (GPCRs) are membrane receptors whose agonist-induced dynamic conformational changes trigger heterotrimeric G protein activation, followed by GRK-mediated phosphorylation and arrestin-mediated desensitization. Cytosolic regions of GPCRs have been studied extensively because they are direct contact sites with G proteins, GRKs, and arrestins. Among various cytosolic regions, the role of helix 8 is least understood, although a few studies have suggested that it is involved in G protein activation, receptor localization, and/or internalization. In the present study, we investigated the role of helix 8 in dopamine receptor signaling focusing on dopamine D1 receptor (D1R) and dopamine D2 receptor (D2R). D1R couples exclusively to Gs, whereas D2R couples exclusively to Gi. Bioinformatic analysis implied that the sequences of helix 8 may affect GPCR-G protein coupling selectivity; therefore, we evaluated if swapping helix 8 between D1R and D2R changed G protein selectivity. Our results suggest that helix 8 is not involved in D1R-Gs or D2R-Gi coupling selectivity. Instead, we observed that D1R with D2R helix 8 or D1R with an increased number of hydrophobic residues in helix 8 relative to wild-type showed diminished β-arrestin-mediated desensitization, resulting in increased Gs signaling.
Arrestin ; Arrestins ; Computational Biology ; Cytosol ; Dopamine ; Family Characteristics ; GTP-Binding Proteins ; Membranes ; Phosphorylation ; Receptors, Dopamine D1 ; Receptors, Dopamine D2 ; Receptors, Dopamine

Arrestins are soluble relatively small 44-46 kDa proteins that specifically bind hundreds of active phosphorylated GPCRs and dozens of non-receptor partners. There are binding partners that demonstrate preference for each of the known arrestin conformations: free, receptor-bound, and microtubule-bound. Recent evidence suggests that conformational flexibility in every functional state is the defining characteristic of arrestins. Flexibility, or plasticity, of proteins is often described as structural disorder, in contrast to the fixed conformational order observed in high-resolution crystal structures. However, protein-protein interactions often involve highly flexible elements that can assume many distinct conformations upon binding to different partners. Existing evidence suggests that arrestins are no exception to this rule: their flexibility is necessary for functional versatility. The data on arrestins and many other multi-functional proteins indicate that in many cases, "order" might be artificially imposed by highly non-physiological crystallization conditions and/or crystal packing forces. In contrast, conformational flexibility (and its extreme case, intrinsic disorder) is a more natural state of proteins, representing true biological order that underlies their physiologically relevant functions.
Animals ; Arrestins ; chemistry ; metabolism ; Humans ; Protein Conformation

The effect of Fructus Mume formula and its separated prescription extract on insulin resistance in type 2 diabetic rats was investigated. The rat model of type 2 diabetes was established by feeding on a high-fat diet for 8 weeks and by subsequently intravenous injection of small doses of streptozotocin. Rats in treatment groups, including the Fructus Mume formula treatment group (FM), the cold property herbs of Fructus Mume formula treatment group (CFM), the warm property herbs of Fructus Mume formula treatment group (WFM), were administrated with Fructus Mume formula and its separated prescription extract by gavage, while the rats in diabetic model group (DM) and metformin group (MET) were given by gavage with normal saline and metformin correspondingly. The body weight before and after treatment was measured, and the oral glucose tolerance test (OGTT) and the insulin release test (IRT) were performed. The homeostasis model assessment-insulin resistance index (HOMA-IR) was calculated. The protein and mRNA expression levels of Insr, β-arrestin-2, Irs-1 and Glut-4 in the liver, skeletal muscle and fat tissues were detected by using Western blotting and RT-PCR respectively. The results demonstrated that, as compared with DM group, OGTT, IRT (0 h, 1 h) levels and HOMR-IR in treatment groups were all reduced, meanwhile their protein and mRNA expression levels of Insr, Irs-1 and Glut-4 in the liver, skeletal muscle and fat tissues were obviously increased, and their protein and mRNA expression levels of β-arrestin-2 in the liver and skeletal muscle tissues were also markedly increased. It was suggested that the Fructus Mume formula and its separated prescription extracts could effectively improve insulin resistance in type 2 diabetic rats, which might be related to the up-regulated expression of Insr, Irs-1 and Glut-4 in the liver, skeletal muscle and fat tissues, and β-arrestin-2 in the liver and skeletal muscle tissues.
Adipose Tissue ; drug effects ; metabolism ; Animals ; Arrestins ; genetics ; metabolism ; Diabetes Mellitus, Experimental ; drug therapy ; metabolism ; Drugs, Chinese Herbal ; pharmacology ; therapeutic use ; Glucose Intolerance ; drug therapy ; Glucose Transporter Type 4 ; genetics ; metabolism ; Hypoglycemic Agents ; pharmacology ; therapeutic use ; Insulin Receptor Substrate Proteins ; genetics ; metabolism ; Insulin Resistance ; Liver ; drug effects ; metabolism ; Male ; Muscle, Skeletal ; drug effects ; metabolism ; RNA, Messenger ; genetics ; metabolism ; Rats ; Rats, Wistar ; Receptor, Insulin ; genetics ; metabolism ; beta-Arrestin 2 ; beta-Arrestins

Animals ; Arrestins ; metabolism ; Liver ; pathology ; Liver Cirrhosis, Experimental ; metabolism ; pathology ; Male ; Mice ; Mice, Inbred ICR ; beta-Arrestins

OBJECTIVETo investigate the signaling pathways involved in β-arrestin1-induced proliferation of K562 cells.

METHODSWe established stable cell lines K562-siβ1 and K562-β1 by lentivirus-mediated β-arrestin1 knock-down or overexpression in K562 cells, with cells transfected with non-specific siRNA as the control (K562-Ctrl). The proliferation of these cells were evaluated by cell counting and CCK-8 assays. Western blotting was used to detect the expression of JNK and p-JNK in the cells, and co-immunoprecipitation (Co-IP) assay was employed to investigate the interaction between β-arrestin1 and Src.

RESULTSK562-β1 cells showed significantly greater but K562-siβ1 cells had significantly lower proliferation ability and cell survival rate than K562-Ctrl cells. Western blotting showed that β-arrestin1 specifically enhanced the expression of p-JNK, and the JNK inhibitor SP600125 obviously suppressed p-JNK and cell proliferation of K562 cells. Co-IP assay revealed the binding of β-arrestin1 to Src.

CONCLUSIONSIn K562 cells, β-arrestin1 activates JNK signaling pathway by binding to Src to promote the cell proliferation.

Arrestins ; metabolism ; Cell Proliferation ; Cell Survival ; Humans ; K562 Cells ; Leukemia, Myelogenous, Chronic, BCR-ABL Positive ; metabolism ; MAP Kinase Signaling System ; RNA, Small Interfering ; beta-Arrestins

This study was aimed to investigate the role of the delta-opioid receptor (DOR)-β-arrestin1-Bcl-2 signal transduction pathway in the pathogenesis of ulcerative colitis (UC) and the intervention effects of oxymatrine on UC. Forty Sprague-Dawley rats were divided into normal group, model group, oxymatrine-treated group and mesalazine-treated group (n=10 each) at random. The rat UC model was established by intra-colonic injection of trinitrobenzene sulfonic acid in the model group and two treatment groups. The rats in oxymatrine-treated group were subjected to intramuscular injection of oxymatrine [63 mg/(kg·day)] for 15 days, and those in mesalazine-treated group given mesalazine solution [0.5 g/(kg·day)] by gastric lavage for the same days. Animals in normal group and model group were administered 3 mL water by gastric lavage for 15 days. On the 16th day, after fasting for 24 h, the rats were sacrificed for the removal of colon tissues. The expression levels of DOR, β-arrestin1 and Bcl-2 were determined in colon tissues by immunohistochemistry and real-time quantitative polymerase chain reaction (RT-PCR), respectively. It was found that the expression levels of DOR, β-arrestin1 and Bcl-2 protein and mRNA were significantly increased in the model group as compared with the other groups (P<0.05). They were conspicuously decreased in both mesalazine-treated and oxymatrine-treated groups in contrast to the model group (P<0.05). No statistically significant difference was noted in these indices between mesalazine- and oxymatrinetreated groups (P>0.05). This study indicated that the DOR-β-arrestin1-Bcl-2 signal transduction pathway may participate in the pathogenesis of UC. Moreover, oxymatrine can attenuate the development of UC by regulating the DOR-β-arrestin1-Bcl-2 signal transduction pathway.
Alkaloids ; pharmacology ; Animals ; Anti-Arrhythmia Agents ; pharmacology ; Arrestins ; metabolism ; Colitis, Ulcerative ; metabolism ; pathology ; prevention & control ; Male ; Proto-Oncogene Proteins c-bcl-2 ; metabolism ; Quinolizines ; pharmacology ; Rats ; Rats, Sprague-Dawley ; Receptors, Opioid, delta ; metabolism ; Signal Transduction ; drug effects ; beta-Arrestins

OBJECTIVETo explore the regulatory mechanism of immune response of guinea pigs sensitized by trichloroethylene (TCE), and the expression level of 3-arrestin, and the activity of NF-kappaB and AP-1 in peripheral blood mononuclear cells (PBMC) of guinea pigs sensitized by TCE.

METHODSGuinea pigs were treated with TCE based on the guinea pig maximum response test (GPMT); Blank control group and DNCB positive control group were established. Scores of skin reaction were evaluated and used to determine whether or not allergy in guinea pig. Then TCE treated group was divided into sensitized group or un-sensitized group. The expression levels of beta-arrestin protein, activity of NF-kappaB and AP-1 in PBMC were detected by Western Blotting and EMSA, respectively. TNF-alpha level in serum was detected by ELISA kits.

RESULTSNo erythema or edema was found in the control group; part of guinea pigs treated with TCE developed erythema and edema, while obvious erythema and edema could be found in DNCB group. The sensitization rates were 71.4% and 100% in TCE and DNCB group, respectively. Compared with TCE un-sensitized group, expression of beta-arrestin and AP-1 activity were not significantly different in TCE sensitized group (P > 0.05). While the NF-kappaB activity was elevated obviously (P < 0.05). Compared with blank control groups [(32.118 +/- 12.550) pg/ml], serum TNF-alpha levels in TCE sensitized groups [(55.485 +/- 8.732) pg/ml] significantly elevated (P < 0.05);

CONCLUSIONIn guinea pigs, beta-arrestin and AP-1 may not be activated, while the NF-kappaB activation is significant, and plays a immune regulatory role in the immune reaction of allergy induced by TCE.

Animals ; Arrestins ; blood ; Edema ; chemically induced ; Erythema ; chemically induced ; Female ; Guinea Pigs ; Hypersensitivity ; blood ; Leukocytes, Mononuclear ; drug effects ; immunology ; metabolism ; NF-kappa B ; blood ; Transcription Factor AP-1 ; blood ; Trichloroethylene ; toxicity ; Tumor Necrosis Factor-alpha ; blood ; beta-Arrestins