Serotonin receptor subtype 6 (5-HT(6)) is a neurotransmitter receptor, which is involved in various brain functions such as memory and mood. It mediates signaling via the interaction with a stimulatory G-protein. Especially, the third intracellular loop (iL3) of 5-HT(6) and the alpha subunit of stimulatory G protein (Galpha(s)) are responsible for the signaling process of 5-HT(6). Chemical compounds that could inhibit the interaction between the iL3 region of 5-HT(6) and Galpha(s) were screened from a chemical library consisted of 5,600 synthetic compounds. One of the identified compounds bound to Galpha(s) and effectively blocked the interaction between Galpha(s) and the iL3 region of 5-HT(6). The identified compound was further shown to reduce the serotonin-induced accumulation of cAMP in 293T cells transformed with 5-HT(6) cDNA. It also lowered the Ca2+ efflux induced by serotonin in cells expressing 5-HT(6) and chimeric Galpha(s5/q). These results indicate that the interaction between the iL3 of 5-HT(6) and Galpha(s) can be exploited for screening of regulatory compounds against the signaling pathway of 5-HT(6).
Animals ; Calcium/metabolism ; Cell Line ; Cephalosporins/*pharmacology ; Cricetinae ; Cricetulus ; Cyclic AMP/biosynthesis ; GTP-Binding Protein alpha Subunits, Gs/antagonists & inhibitors/*metabolism ; Humans ; Receptors, Serotonin/*drug effects/metabolism/*physiology ; Serotonin/pharmacology ; Serotonin Antagonists/pharmacology ; Signal Transduction

OBJECTIVETo observe anti-arrhythmic effect of acupuncture pretreatment in the rat of myocardial ischemia and reperfusion (MIR) and to explore the role of cAMP and Gsa protein in beta-adrenergic receptor signaling.

METHODSMIR was produced by ligation and reperfusion of the left anterior descending coronary artery in the rat. Arrhythmic score, content of cAMP and Gsalpha protein in ischemic myocardium were compared among the normal control (NC), ischemia and reperfusion (IR), electroacupuncture (EA) and EA plus propranolol (EAP) groups.

RESULTSThe arrhythmic score in the IR group at 10 min after reperfusion was higher than the NC group (P < 0.01); in the EA group the score was decreased (P < 0.01 vs the IR group); the score in the EAP group was similar to the IR group, much higher than the EA group (P < 0.01). The similar results for the contents of cAMP and Gsalpha protein were found in the ischemic myocardium. It is suggested that EA pretreatment significantly attenuates the arrhythmic incidence rate and the enhancement of the contents of myocardial cAMP and Gsalpha protein induced by MIR, and the attenuating effect is significantly inhibited by the intraperitoneal pretreatment of propranolol, a specific beta-adrenoceptor antagonist.

CONCLUSIONPretreatment of EA can produce anti-arrhythmic effect in the rat of MIR, which is mediated by the post-receptor signaling pathway of beta-adrenergic receptor.

Acupuncture Therapy ; Animals ; Arrhythmias, Cardiac ; prevention & control ; Calcium ; metabolism ; Cyclic AMP ; analysis ; GTP-Binding Protein alpha Subunits, Gs ; analysis ; Male ; Myocardial Ischemia ; metabolism ; therapy ; Rats ; Rats, Wistar ; Receptors, Adrenergic, beta ; physiology ; Signal Transduction ; physiology

The aim of the present study is to explore the mechanism of estrogen on regulating cardiac function disorder by adjusting the stimulating adenylate cyclase G &alpha; protein (G&alpha;s)-cycle adenosine monophosphate (cAMP) signal pathway. Adult female rats were randomly divided into five groups: sham group, ovariectomized group (OVX), OVX and 17β-estradiol given group (OVX+E₂), OVX and isoprenaline injected group (OVX+ISO), OVX and 17β-estradiol, isoprenaline injected group (OVX+E₂+ISO). Rats were ovariectomized, and two weeks later, OVX+E₂group was injected with E₂, OVX+ISO group was injected with ISO, OVX+E₂+ISO group was injected with E₂and ISO. Another four weeks later, the hemodynamic parameters were monitored by carotid artery intubation: left ventricular systolic pressure (LVSP), left ventricular end-diastolic pressure (LVEDP), maximal differentials of left ventricular developed pressure (+dp/dt(max)), and minimal differentials of left ventricular developed pressure (-dp/dt(max)). Brain natriuretic peptide (BNP) and cAMP concentration in plasma were determined; G&alpha;(s) protein expression in myocardium was determined. The results showed that the hemodynamic parameters, the concentration of BNP and cAMP in plasma had no significant changes after ovariectomy compared with sham group. But after isoprenaline injection in ovariectomized rats, LVSP and +dp/dt(max) declined (P < 0.01), LVEDP and -dp/dt(max) elevated (P < 0.01); plasma BNP concentration increased (P < 0.01); plasma cAMP concentration decreased (P < 0.01), compared with OVX group. Further estrogen supplements improved the heart function treated by isoprenaline: LVSP and +dp/dt(max) elevated (P < 0.01), LVEDP and -dp/dtmax declined (P < 0.05, P < 0.01); the plasma BNP concentration decreased (P < 0.01); the plasma cAMP concentration increased (P < 0.01). Estrogen had no significant influence on G&alpha;s protein expression. The results suggest that estrogen can alleviate myocardial injury and regulate cardiac function disorder by increasing cAMP level, finally improved the excessive suppression of myocardium.
Animals ; Cyclic AMP ; blood ; Estradiol ; pharmacology ; Estrogens ; pharmacology ; Female ; GTP-Binding Protein alpha Subunits, Gs ; metabolism ; Hemodynamics ; Isoproterenol ; adverse effects ; Myocardium ; pathology ; Natriuretic Peptide, Brain ; blood ; Ovariectomy ; Rats ; Signal Transduction

Stimulatory heterotrimeric GTP-binding proteins (Gs protein) stimulate cAMP generation in response to various signals, and modulate various cellular phenomena such as proliferation and apoptosis. This study aimed to investigate the effect of Gs proteins on gamma ray-induced apoptosis of lung cancer cells and its molecular mechanism, as an attempt to develop a new strategy to improve the therapeutic efficacy of gamma radiation. Expression of constitutively active mutant of the alpha subunit of Gs (GalphasQL) augmented gamma ray-induced apoptosis via mitochondrial dependent pathway when assessed by clonogenic assay, FACS analysis of PI stained cells, and western blot analysis of the cytoplasmic translocation of cytochrome C and the cleavage of caspase-3 and ploy(ADP-ribose) polymerase (PARP) in H1299 human lung cancer cells. GalphasQL up-regulated the Bak expression at the levels of protein and mRNA. Treatment with inhibitors of PKA (H89), SP600125 (JNK inhibitor), and a CRE-decoy blocked GalphasQL-stimulated Bak reporter luciferase activity. Expression of GalphasQL increased basal and gamma ray-induced luciferase activity of cAMP response element binding protein (CREB) and AP-1, and the binding of CREB and AP-1 to Bak promoter. Furthermore, prostaglandin E2, a Galphas activating signal, was found to augment gamma ray-induced apoptosis, which was abolished by treatment with a prostanoid receptor antagonist. These results indicate that Galphas augments gamma ray-induced apoptosis by up-regulation of Bak expression via CREB and AP-1 in H1299 lung cancer cells, suggesting that the efficacy of radiotherapy of lung cancer may be improved by modulating Gs signaling pathway.
Apoptosis/*radiation effects ; Cell Line, Tumor ; Cyclic AMP Response Element-Binding Protein/metabolism ; GTP-Binding Protein alpha Subunits, Gs/*metabolism ; *Gamma Rays ; Heterotrimeric GTP-Binding Proteins/metabolism ; Humans ; Lung/*cytology/physiology/radiation effects ; Lung Neoplasms ; Transcription Factor AP-1/metabolism ; *Up-Regulation ; bcl-2 Homologous Antagonist-Killer Protein/*metabolism

OBJECTIVETo study the significance of c-myc, p53 and p16 protein expression in fibrous dysplasia, to detect the GNAS1 gene mutation in fibrous dysplasia, and to explore the property of fibrous dysplasia.

METHODSThe expression of c-myc, p53 and p16 protein was evaluated by immunohistochemistry SP method in 35 cases of fibrous dysplasia including 1 FD with malignancy, 1 Mazabraud syndrome and 20 control cases (10 cases of bony callus, 10 cases of osteosarcoma). Genomic DNA extraction, PCR amplification and gene sequencing were used to detect GNAS1 gene mutation in 35 cases of fibrous dysplasia.

RESULTSC-myc protein immunoreactivity was detected in 91 percentage of FD (P = 0.001). Compared with the negative control group, the difference was significant. P16 positive was detected in 34 FD cases (P = 0.001). The difference was significant as compared with the positive control group. Positive p53 protein expression was detected in the only 1 case of fibrous dysplasia with malignant transformation. PCR amplification was successful in 12 of 35 FD cases. Two of the 12 FD cases were detected to have GNAS1 gene mutation, in which 1 case was FD of Mazabraud syndrome, 1 case was a monostotic lesion.

CONCLUSIONSC-myc could be another protooncogene in addition to c-fos in the fibrous dysplasia disease. P53 protein overexpression could be useful in the diagnosis of FD malignancy and in the prediction of the prognosis of FD. The abnormal expression of the gene p16 might play an important role in the formation of FD. The GNAS1 mutation exist in FD. All of the results indicate that FD could be a neoplasia disease, caused by multiple factors leading to a dysfunction of bone development.

Adolescent ; Adult ; Child ; Chromogranins ; Cyclin-Dependent Kinase Inhibitor p16 ; metabolism ; Female ; Fibrous Dysplasia of Bone ; genetics ; metabolism ; pathology ; GTP-Binding Protein alpha Subunits, Gs ; genetics ; Humans ; Male ; Middle Aged ; Mutation ; Osteosarcoma ; genetics ; metabolism ; pathology ; Proto-Oncogene Proteins c-myc ; metabolism ; Tumor Suppressor Protein p53 ; metabolism ; Young Adult

Heterotrimeric GTP-binding proteins (G proteins) transduce extracellular signals into intracellular signals by activating effector molecules including adenylate cyclases that catalyze cAMP formation, and thus regulate various cellular responses such as metabolism, proliferation, and apoptosis. cAMP signaling pathways have been reported to protect cells from ionizing radiation-induced apoptosis, but however, the protective mechanism is not clear. Therefore, this study aimed to investigate the signaling molecules and the mechanism mediating the anti-apoptotic action of cAMP signaling system in radiation-induced apoptosis. Stable expression of a constitutively active mutant of G alpha s (G alpha sQL) protected gamma ray-induced apoptosis which was assessed by analysis of the cleavages of PARP, caspase-9, and caspase-3 and cytochrome C release in SH-SY5Y human neuroblastoma cells. G alpha sQL repressed the gamma ray-induced down-regulation of Bcl-xL protein, but transfection of Bcl-xL siRNA increased the gamma ray-induced apoptosis and abolished the anti-apoptotic effect of G alpha sQL. G alpha sQL decreased the degradation rate of Bcl-xL protein, and it also restrained the decrease in Bcl-xL mRNA by increasing the stability following ionizing irradiation. Furthermore, prostaglandin E2 that activates G alpha s was found to protect gamma ray-induced apoptosis, and the protective effect was abolished by treatment with prostanoid receptor antagonist specific to EP2/4R subtype. Moreover, specific agonists for adenosine A1 receptor that inhibits cAMP signaling pathway augmented gamma ray-induced apoptosis. From this study, it is concluded that Galphas-cAMP signaling system can protect SH-SY5Y cells from gamma ray-induced apoptosis partly by restraining down-regulation of Bcl-xL expression, suggesting that radiation-induced apoptosis can be modulated by GPCR ligands to improve the efficiency of radiation therapy.
Apoptosis/*physiology/*radiation effects ; Base Sequence ; Cell Line, Tumor ; Cyclic AMP/metabolism ; DNA Primers/genetics ; Down-Regulation/radiation effects ; GTP-Binding Protein alpha Subunits, Gs/*metabolism ; Gamma Rays ; Humans ; Neuroblastoma/genetics/metabolism/pathology ; RNA, Small Interfering/genetics ; Signal Transduction ; bcl-X Protein/genetics/*metabolism

BACKGROUNDThe addition of anti-human epidermal growth factor receptor 2 (HER2)-targeted drugs, such as trastuzumab, lapatinib, and trastuzumab emtansine (T-DM1), to chemotherapy significantly improved prognosis of HER2-positive breast cancer patients. However, it was confused that metastatic patients vary in the response of targeted drug. Therefore, methods of accurately predicting drug response were really needed. To overcome the spatial and temporal limitations of biopsies, we aimed to develop a more sensitive and less invasive method of detecting mutations associated with anti-HER2 therapeutic response through circulating-free DNA (cfDNA).

METHODSFrom March 6, 2014 to December 10, 2014, 24 plasma samples from 20 patients with HER2-positive metastatic breast cancer who received systemic therapy were eligible. We used a panel for detection of hot-spot mutations from 50 oncogenes and tumor suppressor genes, and then used targeted next-generation sequencing (NGS) to identify somatic mutation of these samples in those 50 genes. Samples taken before their first trastuzumab administration and subsequently proven with clinical benefit were grouped into sensitive group. The others were collected after disease progression of the trastuzumab-based therapy and were grouped into the resistant group.

RESULTSA total of 486 single-nucleotide variants from 46 genes were detected. Of these 46 genes, phosphatidylinositol 4,5-bisphosphate 3-kinase catalytic subunit alpha (PIK3CA), proto-oncogene c-Kit (KIT), and tumor protein p53 (TP53) were the most common mutated genes. Seven genes, including epidermal growth factor receptor (EGFR), G protein subunit alpha S (GNAS), HRas proto-oncogene (HRAS), mutL homolog 1 (MLH1), cadherin 1 (CDH1), neuroblastoma RAS viral oncogene homolog (NRAS), and NOTCH1, that only occurred m utations in the resistant group were associated with the resistance of targeted therapy. In addition, we detected a HER2 S855I mutation in two patients who had persistent benefits from anti-HER2 therapy.

CONCLUSIONTargeted NGS of cfDNA has potential clinical utility to detect biomarkers from HER2-targeted therapies.

Adolescent ; Adult ; Aged ; Biomarkers, Tumor ; genetics ; Breast Neoplasms ; genetics ; metabolism ; Cadherins ; genetics ; Chromogranins ; genetics ; Class I Phosphatidylinositol 3-Kinases ; Drug Resistance, Neoplasm ; genetics ; Female ; GTP-Binding Protein alpha Subunits, Gs ; genetics ; Humans ; Male ; Middle Aged ; Mutation ; genetics ; Phosphatidylinositol 3-Kinases ; genetics ; Proto-Oncogene Proteins c-kit ; genetics ; Receptor, ErbB-2 ; metabolism ; Receptor, Notch1 ; genetics ; Tumor Suppressor Protein p53 ; genetics ; Young Adult

AIMTo explore the role of clonidine (Clo) on myocardial Gs alpha mRNA expression after scalds in rats.

METHODSA 30% skin-full-thickness scald was produced by immersing rats in 95 degrees C water for 10 s. The myocardial Gs alpha mRNA expression level, cyclic AMP content and adenylyl cyclase (AC) activity were determined with dot blotting hybridization, in situ hybridization, radioimmunoassay and indirect method.

RESULTSThree hours after scalds, the myocardial Gs alpha mRNA was significantly decreased to (61 +/- 20)% of the control group (P < 0.01). AC activity and cAMP content were also decreased. Clo (0.3, 1.0 and 3.0 mg.kg-1, i.p.) was shown to increase myocardial Gs alpha mRNA expression level (P < 0.01 or P < 0.05) after scalds to (131 +/- 28)%, (142 +/- 51)% and (139 +/- 48)% of the scald group, respectively, which were correlated with the Clo dose (gamma = 0.597, P < 0.05). Clo 1.0 mg.kg-1 and 3.0 mg.kg-1 (i.p.) promoted AC activity and increased cAMP content, but Clo 0.3 and 0.1 mg.kg-1 showed no significant effect (P > 0.05). Selective I1-imidazoline receptor antagonist efaroxan (Efa) (10, 5 mg.kg-1, i.p.) was found to partially reverse the effect of Clo, while Efa 2.5 mg.kg-1 showed no significantly influence. The reduced quantity of Gs alpha mRNA expression level correlated well with the Efa dose (gamma = 0.900, P < 0.05). The change of AC and cAMP was similar to Gs alpha mRNA.

CONCLUSIONClo increased the myocardial Gs alpha mRNA expression, AC activity and cAMP content after scalds in rats.

Adenylyl Cyclases ; metabolism ; Adrenergic beta-Agonists ; pharmacology ; Animals ; Burns ; metabolism ; Clonidine ; pharmacology ; Cyclic AMP ; metabolism ; Dose-Response Relationship, Drug ; GTP-Binding Protein alpha Subunits, Gs ; biosynthesis ; genetics ; Gene Expression ; drug effects ; Heart ; drug effects ; Male ; Myocardium ; metabolism ; RNA, Messenger ; biosynthesis ; drug effects ; Random Allocation ; Rats ; Rats, Wistar

OBJECTIVETo analyze the association between T393C single nucleotide polymorphism (SNP) of GNAS1 gene and non-valvular atrial fibrillation (AF) in Chinese Han patients.

METHODSNinety patients with non-valvular AF and 90 healthy subjects were examined for T393C SNP of GNAS1 gene using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). The allele genotypes and the distribution of allele frequencies were analyzed and compared between the two groups. The relationship between allele frequency distribution characteristics and the heart rate variability (HRV) were also studied for analysis of the association between T393C SNP of GNAS1 gene and the autonomic nervous activation in non-valvular AF.

RESULTSThe two groups showed a significant difference in the frequencies of genotypes of T393C SNP of GNAS1 gene and allele frequencies (P<0.01). CC genotype and T393C allele frequency were significantly increased in the case group. pNN50, LF, or LF/HF showed no significant difference between different genotypes (P<0.05).

CONCLUTIONSThe T393C SNP of GNAS1 gene is closely associated with non-valvular AF in Chinese Han patients.

Adult ; Aged ; Aged, 80 and over ; Alleles ; Asian Continental Ancestry Group ; genetics ; Atrial Fibrillation ; genetics ; metabolism ; physiopathology ; Chromogranins ; Female ; GTP-Binding Protein alpha Subunits, Gs ; genetics ; Gene Frequency ; Genotype ; Heart Rate ; Humans ; Male ; Middle Aged ; Polymerase Chain Reaction ; Polymorphism, Restriction Fragment Length ; Polymorphism, Single Nucleotide ; Risk Factors