1.Effects of Glucocorticoid-Induced Transcript 1 Gene Deficiency on Glucocorticoid Activation in Asthmatic Mice.
Cheng-Ping HU ; Qiu-Fen XUN ; Xiao-Zhao LI ; Xin-Yue HU ; Ling QIN ; Ruo-Xi HE ; Jun-Tao FENG
Chinese Medical Journal 2018;131(23):2817-2826
		                        		
		                        			Background:
		                        			Glucocorticoid (GC) is the first-line therapy for asthma, but some asthmatics are insensitive to it. Glucocorticoid-induced transcript 1 gene (GLCCI1) is reported to be associated with GCs efficiency in asthmatics, while its exact mechanism remains unknown.
		                        		
		                        			Methods:
		                        			A total of 30 asthmatic patients received fluticasone propionate for 12 weeks. Forced expiratory volume in 1 s (FEV) and GLCCI1 expression were detected. Asthma model was constructed in wild-type and GLCCI1 knockout (GLCCI1) mice. Glucocorticoid receptor (GR) and mitogen-activated protein kinase phosphatase 1 (MKP-1) expression were detected by polymerase chain reaction and Western blotting (WB). The phosphorylation of p38 mitogen-activated protein kinase (MAPK) was also detected by WB.
		                        		
		                        			Results:
		                        			In asthmatic patients, the change of FEV was well positively correlated with change of GLCCI1 expression (r = 0.430, P = 0.022). In animal experiment, GR and MKP-1 mRNA levels were significantly decreased in asthmatic mice than in control mice (wild-type: GR: 0.769 vs. 1.000, P = 0.022; MKP-1: 0.493 vs. 1.000, P < 0.001. GLCCI1: GR: 0.629 vs. 1.645, P < 0.001; MKP-1: 0.377 vs. 2.146, P < 0.001). Hydroprednisone treatment significantly increased GR and MKP-1 mRNA expression levels than in asthmatic groups; however, GLCCI1 asthmatic mice had less improvement (wild-type: GR: 1.517 vs. 0.769, P = 0.023; MKP-1: 1.036 vs. 0.493, P = 0.003. GLCCI1: GR: 0.846 vs. 0.629, P = 0.116; MKP-1: 0.475 vs. 0.377, P = 0.388). GLCCI1 asthmatic mice had more obvious phosphorylation of p38 MAPK than wild-type asthmatic mice (9.060 vs. 3.484, P < 0.001). It was still higher even though after hydroprednisone treatment (6.440 vs. 2.630, P < 0.001).
		                        		
		                        			Conclusions:
		                        			GLCCI1 deficiency in asthmatic mice inhibits the activation of GR and MKP-1 and leads to more obvious phosphorylation of p38 MAPK, leading to a decremental sensitivity to GCs.
		                        		
		                        			Trial Registration
		                        			ChiCTR.org.cn, ChiCTR-RCC-13003634; http://www.chictr.org.cn/showproj.aspx?proj=5926.
		                        		
		                        		
		                        		
		                        			Animals
		                        			;
		                        		
		                        			Asthma
		                        			;
		                        		
		                        			drug therapy
		                        			;
		                        		
		                        			metabolism
		                        			;
		                        		
		                        			Dual Specificity Phosphatase 1
		                        			;
		                        		
		                        			genetics
		                        			;
		                        		
		                        			metabolism
		                        			;
		                        		
		                        			Forced Expiratory Volume
		                        			;
		                        		
		                        			genetics
		                        			;
		                        		
		                        			physiology
		                        			;
		                        		
		                        			Glucocorticoids
		                        			;
		                        		
		                        			therapeutic use
		                        			;
		                        		
		                        			Mice
		                        			;
		                        		
		                        			Mice, Knockout
		                        			;
		                        		
		                        			Phosphorylation
		                        			;
		                        		
		                        			genetics
		                        			;
		                        		
		                        			physiology
		                        			;
		                        		
		                        			Receptors, Glucocorticoid
		                        			;
		                        		
		                        			deficiency
		                        			;
		                        		
		                        			genetics
		                        			;
		                        		
		                        			metabolism
		                        			;
		                        		
		                        			p38 Mitogen-Activated Protein Kinases
		                        			;
		                        		
		                        			genetics
		                        			;
		                        		
		                        			metabolism
		                        			
		                        		
		                        	
2.Nr2e1 Downregulation Is Involved in Excess Retinoic Acid-induced Developmental Abnormality in the Mouse Brain.
Juan YU ; Qian GUO ; Jian Bing MU ; Ting ZHANG ; Ren Ke LI ; Jun XIE
Biomedical and Environmental Sciences 2017;30(3):185-193
OBJECTIVEThis study aimed to investigate the expression pattern and function of Nuclear receptor subfamily 2 group E member 1 (Nr2e1) in retinoic acid (RA)-induced brain abnormality.
METHODSThe mouse model of brain abnormality was established by administering 28 mg/kg RA, and neural stem cells (NSCs) were isolated from the mouse embryo and cultured in vitro. Nr2e1 expression was detected by whole mount in situ hybridization, RT-PCR, and Western blotting. Nr2e1 function was determined by transducing Nr2e1 shRNA into NSCs, and the effect on the sonic hedgehog (Shh) signaling pathway was assessed in the cells. In addition, the regulation of Nr2e1 expression by RA was also determined in vitro.
RESULTSNr2e1 expression was significantly downregulated in the brain and NSCs of RA-treated mouse embryos, and knockdown of Nr2e1 affected the proliferation of NSCs in vitro. In addition, a similar expression pattern of Nr2e1 and RA receptor (RAR) α was observed after treatment of NSCs with different concentrations of RA.
CONCLUSIONOur study demonstrated that Nr2e1 could be regulated by RA, which would aid a better understanding of the mechanism underlying RA-induced brain abnormality.
Animals ; Brain ; cytology ; embryology ; Cell Proliferation ; Down-Regulation ; Gene Expression Regulation ; Gene Expression Regulation, Developmental ; drug effects ; Mice ; Mice, Inbred C57BL ; Neural Stem Cells ; drug effects ; physiology ; Receptors, Cytoplasmic and Nuclear ; genetics ; metabolism ; Tretinoin ; pharmacology
3.Effects of apigenin on self-renewal and uPAR expression in NCI-H446 cell line.
Ling SHU ; Qing YUAN ; Yinghong CUI ; Shuwen SUN ; A CHEN ; Dan CHEN ; Jianguo CAO ; Jiansong ZHANG
Journal of Central South University(Medical Sciences) 2016;41(11):1124-1127
		                        		
		                        			
		                        			To investigate the effect of apigenin on self-renewal for sphere-forming cells in human small cell lung cancer cell line NCI-H446 and the underlying mechanisms.
 Methods: Sphere-forming cells from NCI-H446 cell line were cultured in stem cell-conditioned culture medium with ultra-low attachment surface plates. The rate of sphere-forming cells in the second passage sphere-forming cells was used to evaluate the inhibitory effects of apigenin on the self-renewal for sphere-forming cells. The protein level of urokinase-type plasminogen activator receptor (uPAR) in spheroids was analyzed by Western blot.
 Results: Apigenin signifcantly inhibited the self-renewal of the second passage sphere-forming cells [0, 5.0, 10.0, 20.0 μmol/L apigenin: (18.2±1.9)%, (13.6±1.7)%, (10.6±1.6)%, (6.9±1.3)%, respectively] and down-regulated uPAR expression in a concentration-dependent manner (P<0.05).
 Conclusion: Apigenin inhibits the self-renewal capacity of sphere-forming cells in NCI-H446 cells, which may be associated with down-regulation of uPAR expression.
		                        		
		                        		
		                        		
		                        			Apigenin
		                        			;
		                        		
		                        			pharmacology
		                        			;
		                        		
		                        			Cell Line, Tumor
		                        			;
		                        		
		                        			Down-Regulation
		                        			;
		                        		
		                        			drug effects
		                        			;
		                        		
		                        			genetics
		                        			;
		                        		
		                        			Humans
		                        			;
		                        		
		                        			Lung Neoplasms
		                        			;
		                        		
		                        			Neoplastic Stem Cells
		                        			;
		                        		
		                        			drug effects
		                        			;
		                        		
		                        			pathology
		                        			;
		                        		
		                        			physiology
		                        			;
		                        		
		                        			Receptors, Cell Surface
		                        			;
		                        		
		                        			Receptors, Urokinase Plasminogen Activator
		                        			;
		                        		
		                        			drug effects
		                        			;
		                        		
		                        			genetics
		                        			;
		                        		
		                        			metabolism
		                        			;
		                        		
		                        			Signal Transduction
		                        			;
		                        		
		                        			Small Cell Lung Carcinoma
		                        			;
		                        		
		                        			drug therapy
		                        			;
		                        		
		                        			pathology
		                        			;
		                        		
		                        			Spheroids, Cellular
		                        			;
		                        		
		                        			drug effects
		                        			;
		                        		
		                        			physiology
		                        			;
		                        		
		                        			Stem Cells
		                        			
		                        		
		                        	
4.Research on hepatitis C virus entry inhibitor.
Zeng WENTING ; Xuemei LU ; Jie WANG ; Xiaobao JIN ; Jiayong ZHU
Chinese Journal of Virology 2015;31(1):97-105
		                        		
		                        			
		                        			Hepatitis c virus (HCV) infection has become one of the global public health problem,while there is no vaccine to prevent HCV infection, the so-called "cocktail" therapy that use a combination of drugs targeting multiple steps in the HCV infection cycle could achieve better curative effect. the process of HCV entering into host cell is the important step of drug intervention, in which HCV envelope protein El and E2, Host cell factors including Heparan sulfate(HS), CD81, scavenger receptor class B type I (SR-BI), Occludin (OCLD), Claudin (CLDN), low densitity lipoprotein receptor (LDLR), dendritic cell-specific ICAM-3-grabbing nonintegrin (DC-SIGN), Liver/lymph node specific ICAM-3-grabbing integrin(L-SIGN), trans- ferrin receptor 1 (TfR1) and so on play a important role. The virus and the host factors can be used as targets of hcv entry inhibitors many studies have shown that as novel and promising compounds, HCV entry inhibitors combinating with other drugs can be more effective in the treatment of HCV, this paper have re- viewed targets and inhibitors of HCV enterring into host cell since 1990s.
		                        		
		                        		
		                        		
		                        			Animals
		                        			;
		                        		
		                        			Antiviral Agents
		                        			;
		                        		
		                        			pharmacology
		                        			;
		                        		
		                        			Hepacivirus
		                        			;
		                        		
		                        			drug effects
		                        			;
		                        		
		                        			physiology
		                        			;
		                        		
		                        			Hepatitis C
		                        			;
		                        		
		                        			genetics
		                        			;
		                        		
		                        			metabolism
		                        			;
		                        		
		                        			virology
		                        			;
		                        		
		                        			Humans
		                        			;
		                        		
		                        			Receptors, Virus
		                        			;
		                        		
		                        			genetics
		                        			;
		                        		
		                        			metabolism
		                        			;
		                        		
		                        			Viral Envelope Proteins
		                        			;
		                        		
		                        			genetics
		                        			;
		                        		
		                        			metabolism
		                        			;
		                        		
		                        			Virus Internalization
		                        			;
		                        		
		                        			drug effects
		                        			
		                        		
		                        	
5.Effect of Zhuangyao Jianshen Wan (ZYJCW) on P2X1 and P2X3 mRNA expressions in rats with diuresis caused by kidney deficiency.
Jia-yi CHEN ; Wei-wen JIANG ; Feng-lei HE ; Guo-qiang MO ; Zhong-hui GUO ; Xiao-dan WANG ; Qing-he WU ; Hong-yin CAO
China Journal of Chinese Materia Medica 2015;40(15):3059-3062
		                        		
		                        			
		                        			To investigate the urination-reducing effect and mechanism of Zhuangyao Jianshen Wan (ZYJCW). In this study, SI rats were subcutaneously injected with 150 mg · kg(-1) dose of D-galactose to prepare the sub-acute aging model and randomly divided into the model group, the Suoquan Wan group (1.17 g · kg(-1) · d(-1)), and ZYJCW high, medium and low dose groups (2.39, 1.20, 0.60 g · kg(-1) · d(-1)) , with normal rats in the blank group. They were continuously administered with drugs for eight weeks. The metabolic cage method was adopted to measure the 24 h urine volume and 5 h water load urine volume in rats. The automatic biochemistry analyzer was adopted to detect urine concentrations of Na+, Cl-, K+. The ELISA method was used to determine serum aldosterone (ALD) and antidiuretic hormone (ADH). The changes in P2X1 and P2X3 mRNA expressions in bladder tissues of rats were detected by RT-PCR. According to the results, both ZYJCW high and medium dose groups showed significant down-regulations in 24 h urine volume and 5 h water load urine volume in (P <0.05, P <0.01), declines in Na+ and Cl- concentrations in urine (P <0.01), notable rises in plasma ALD and ADH contents (P <0.05, P <0.01) and remarkable down-regulations in the P2X1 and P2X3 mRNA expressions in bladder tissues (P <0.01). The ZYJCW low dose group revealed obvious reductions in Na+ and Cl- concentrations in urine (P <0.01). The results indicated that ZYJCW may show the urination-reducing effect by down-regulating the P2X1 and P2X3 mRNA expressions in bladder tissues of rats with diuresis caused by kidney deficiency.
		                        		
		                        		
		                        		
		                        			Aging
		                        			;
		                        		
		                        			physiology
		                        			;
		                        		
		                        			Animals
		                        			;
		                        		
		                        			Diuresis
		                        			;
		                        		
		                        			drug effects
		                        			;
		                        		
		                        			Drugs, Chinese Herbal
		                        			;
		                        		
		                        			pharmacology
		                        			;
		                        		
		                        			Female
		                        			;
		                        		
		                        			Gene Expression Regulation
		                        			;
		                        		
		                        			Kidney Diseases
		                        			;
		                        		
		                        			drug therapy
		                        			;
		                        		
		                        			metabolism
		                        			;
		                        		
		                        			RNA, Messenger
		                        			;
		                        		
		                        			analysis
		                        			;
		                        		
		                        			Rats
		                        			;
		                        		
		                        			Rats, Sprague-Dawley
		                        			;
		                        		
		                        			Receptors, Purinergic P2X1
		                        			;
		                        		
		                        			genetics
		                        			;
		                        		
		                        			Receptors, Purinergic P2X3
		                        			;
		                        		
		                        			genetics
		                        			;
		                        		
		                        			Urinary Bladder
		                        			;
		                        		
		                        			metabolism
		                        			
		                        		
		                        	
6.Effects of Jisuikang on Nogo-NgR gene expression in spinal cord rats with injury.
Wu-Lin YOU ; Ya-Feng ZHANG ; Jian-Feng CHEN ; Heng YIN ; Jun-Feng YANG ; Jian-Wei WANG
China Journal of Orthopaedics and Traumatology 2015;28(3):235-239
OBJECTIVETo study the effects of Jisuikang (Chinese characters) on Nogo-NgR gene expression, and to explore the protective effects and mechanism of Jisuikang (Chinese characters) on spinal cord injury in rats.
METHODSOne hundred eighty female rats were randomly assigned to 6 groups(30 rats per group). Sham group: T10 lamina was resected only and spinal cord was untreated. Model group: spine cord injury (SCI) was created with a modified impinger of Allen's by impacting on the T10 spinal cord. Prednisolone group: Prednisolone (0.06 g/kg) was given by intragastric administration at a time interval of 24 hours after operation. The Jisuikang (Chinese characters) high, moderate and low dose groups: Jisuikang (Chinese characters) was supplied with different dose (50 g/kg, 25 g/kg, 12.5 g/kg) by intragastric administration in rats after operation,for the first time at 30 min after surgery. Animals were killed 3, 7, 14 days after surgery. The expression levels of Nogo-A and NgR were observed by Western Blot and Real-time PCR.
RESULTSThe expression of Nogo-A and NgR was at the basic level at all time points in sham group. Compared with model group, the protein expression levels of Nogo-A and NgR in sham, prednisolone, Jisuikang (Chinese characters) moderate dose groups were statistically significant at all time points (P < 0.05). No difference was found in Jisuikang (Chinese characters) high and low dose groups (P > 0.05). Three days after surgery, the mRNA levels of Nogo-A and NgR in treatment group were significantly lower than that in model group (P < 0.01); 7 days after surgery,Nogo-A and NgR mRNA expression were dramatically upregulated and peaked; 14 days after operation, the expression was decreased, but still significantly higher than that in other treatment groups (P < 0.01). Prednisolone and Jisuikang (Chinese characters) moderate dose groups showed the most significant effects among all groups,but there was no statistically significant difference between two groups (P > 0.05).
CONCLUSIONThe decoction Jisuikang (Chinese characters) can promote the nerve cell regeneration by regulating Nogo-A and NgR gene expression, activating Nogo- NgR signaling pathways after acute spinal cord injury.
Animals ; Female ; GPI-Linked Proteins ; analysis ; genetics ; physiology ; Medicine, Chinese Traditional ; Myelin Proteins ; analysis ; genetics ; physiology ; Nerve Regeneration ; drug effects ; Nogo Proteins ; Nogo Receptor 1 ; Rats ; Rats, Sprague-Dawley ; Receptors, Cell Surface ; analysis ; genetics ; physiology ; Signal Transduction ; drug effects ; Spinal Cord Injuries ; drug therapy ; metabolism
7.Effects of exposure to aluminum on long-term potentiation and AMPA receptor subunits in rats in vivo.
Jing SONG ; Ying LIU ; Hui Fang ZHANG ; Qin Li ZHANG ; Qiao NIU
Biomedical and Environmental Sciences 2014;27(2):77-84
OBJECTIVETo explore the effects of exposure to aluminum (Al) on long-term potentiation (LTP) and AMPA receptor subunits in rats in vivo.
METHODSDifferent dosages of aluminum-maltolate complex [Al(mal)3] were given to rats via acute intracerebroventricular (i.c.v.) injection and subchronic intraperitoneal (i.p.) injection. Following Al exposure, the hippocampal LTP were recorded by field potentiation technique in vivo and the expression of AMPAR subunit proteins (GluR1 and GluR2) in both total and membrane-enriched extracts from the CA1 area of rat hippocampus were detected by Western blot assay.
RESULTSAcute Al treatment produced dose-dependent suppression of LTP in the rat hippocampus and dose-dependent decreases of GluR1 and GluR2 in membrane extracts; however, no similar changes were found in the total cell extracts, which suggests decreased trafficking of AMPA receptor subunits from intracellular pools to synaptic sites in the hippocampus. The dose-dependent suppressive effects on LTP and the expression of AMPA receptor subunits both in the membrane and in total extracts were found after subchronic Al treatment, indicating a decrease in AMPA receptor subunit trafficking from intracellular pools to synaptic sites and an additional reduction in the expression of the subunits.
CONCLUSIONAl(mal)3 obviously and dose-dependently suppressed LTP in the rat hippocampal CA1 region in vivo, and this suppression may be related to both trafficking and decreases in the expression of AMPA receptor subunit proteins. However, the mechanisms underlying these observations need further investigation.
Aluminum ; toxicity ; Animals ; Down-Regulation ; drug effects ; genetics ; physiology ; Hippocampus ; drug effects ; physiology ; Long-Term Potentiation ; drug effects ; genetics ; physiology ; Male ; Protein Transport ; drug effects ; genetics ; physiology ; Random Allocation ; Rats ; Receptors, AMPA ; antagonists & inhibitors ; genetics ; metabolism ; Toxicity Tests, Acute ; Toxicity Tests, Subchronic
8.Three cases of permanent neonatal diabetes mellitus: genotypes and management outcome.
Singapore medical journal 2012;53(7):e142-4
		                        		
		                        			
		                        			Neonatal diabetes mellitus (DM) is defined as insulin-requiring DM in the first six months of life. Unlike type 1 DM, it is a monogenic disorder resulting from a de novo mutation in the genes involved in the development of the pancreas, β-cell mass or secretory function. The majority of neonatal DM cases are caused by a heterozygous activating mutation in the KCNJ11 or ABCC8 genes that encode the Kir6.2 and SUR1 protein subunits, respectively, in the KATP channel. Sulphonylurea, a KATP channel inhibitor, can restore insulin secretion, hence offering an attractive alternative to insulin therapy. We report three cases of neonatal DM and their genetic mutations. Two patients were successfully switched over to sulphonylurea monotherapy with resultant improvement in the quality of life and a more stable blood glucose profile. Patients with neonatal DM should undergo genetic evaluation. For patients with KCNJ11 and ABCC8 gene mutation, oral sulphonylurea should be considered.
		                        		
		                        		
		                        		
		                        			ATP-Binding Cassette Transporters
		                        			;
		                        		
		                        			genetics
		                        			;
		                        		
		                        			Blood Glucose
		                        			;
		                        		
		                        			metabolism
		                        			;
		                        		
		                        			Diabetes Mellitus
		                        			;
		                        		
		                        			genetics
		                        			;
		                        		
		                        			therapy
		                        			;
		                        		
		                        			Female
		                        			;
		                        		
		                        			Genotype
		                        			;
		                        		
		                        			Heterozygote
		                        			;
		                        		
		                        			Humans
		                        			;
		                        		
		                        			Infant
		                        			;
		                        		
		                        			Infant, Newborn
		                        			;
		                        		
		                        			Male
		                        			;
		                        		
		                        			Models, Biological
		                        			;
		                        		
		                        			Models, Genetic
		                        			;
		                        		
		                        			Molecular Biology
		                        			;
		                        		
		                        			Mutation
		                        			;
		                        		
		                        			Pancreas
		                        			;
		                        		
		                        			physiology
		                        			;
		                        		
		                        			Potassium Channels, Inwardly Rectifying
		                        			;
		                        		
		                        			genetics
		                        			;
		                        		
		                        			Quality of Life
		                        			;
		                        		
		                        			Receptors, Drug
		                        			;
		                        		
		                        			genetics
		                        			;
		                        		
		                        			Sulfonylurea Compounds
		                        			;
		                        		
		                        			therapeutic use
		                        			;
		                        		
		                        			Sulfonylurea Receptors
		                        			
		                        		
		                        	
9.Role of ADAM10 and ADAM17 in CD16b shedding mediated by different stimulators.
Sha GUO ; Min PENG ; Qing ZHAO ; Wei ZHANG
Chinese Medical Sciences Journal 2012;27(2):73-79
OBJECTIVETo investigate the main proteinases responsible for CD16b shedding under different stimulators.
METHODSHEK293 cell line stably expressing CD16b was constructed by lentivirus system. The cell line was then overexpressed with a disintegrin and metalloproteinase 10 (ADAM10) or ADAM17, suppressed with short hairpin RNA of ADAM10 or ADAM17, and reconstituted with ADAM10 or ADAM17, respectively. After each treatment, the cell line was stimulated with ionomycin or phorbol 12-myristate- 13-acetate (PMA) for 12 hours. The soluble CD16b released from cell membrane was detected by immunoprecipition and immunoblot. Quantitation was then implemented to compare the amount of soluble CD16b in cell supernatant after stimulation.
RESULTSHEK293 cell line stably expressing CD16b was successfully established. When CD16b expressing cell line was overexpressed with ADAM10, shedding of CD16b was increased after stimulation with ionomycin but not PMA; when the cell line overexpressed with ADAM17, shedding of CD16b was increased after stimulation with PMA but not ionomycin. Similarly, when ADAM10 was suppressed by short hairpin RNA, CD16b shedding was decreased after stimulation with ionomycin; when ADAM17 was suppressed by short hairpin RNA, CD16b shedding was decreased after stimulation with PMA. The shedding of CD16b was increased again when CD16b expressing cell line was reconstituted with ADAM10 and stimulated by ionomycin or reconstituted with ADAM17 and stimulated by PMA.
CONCLUSIONSBoth ADAM10 and ADAM17 could shed CD16b, but they possess differed preferences. ADAM10 is the main sheddase under stimulation of ionomycin, while ADAM17 is the main sheddase under stimulation of PMA.
ADAM Proteins ; genetics ; metabolism ; physiology ; ADAM10 Protein ; ADAM17 Protein ; Amyloid Precursor Protein Secretases ; genetics ; metabolism ; physiology ; Calcium Ionophores ; pharmacology ; Carcinogens ; pharmacology ; Cells, Cultured ; Drug Evaluation, Preclinical ; GPI-Linked Proteins ; metabolism ; Gene Knockdown Techniques ; HEK293 Cells ; Humans ; Ionomycin ; pharmacology ; Membrane Proteins ; genetics ; metabolism ; physiology ; Protein Processing, Post-Translational ; drug effects ; Protein Transport ; drug effects ; Proteolysis ; drug effects ; Receptors, IgG ; metabolism ; Tetradecanoylphorbol Acetate ; pharmacology ; Transfection
10.Mg(2+) inhibits ATP-activated current mediated by rat P2X4 receptors expressed in Xenopus oocytes.
Fang PENG ; Yu-Qin ZHANG ; Yan ZENG ; Yan-Ling ZHOU
Acta Physiologica Sinica 2012;64(1):75-81
		                        		
		                        			
		                        			To investigate the modulation of Mg(2+) on rat P2X4 receptors and its underlying mechanism, we transcribed cDNA coding for wild-type and mutant P2X4 receptors to cRNA in vitro, injected the cRNA to oocytes of Xenopus laevis using the microinjection technique and revealed the effect of Mg(2+) on ATP-activated currents (I(ATP)) mediated by P2X4 receptors using the two-electrode whole-cell voltage clamp technique. The effects of extracellular Mg(2+) on I(ATP) were as follows: (1) In oocytes expressing P2X4 receptors, Mg(2+) with concentration ranging from 0.5-10 mmol/L inhibited the amplitude of I(ATP) in a concentration-dependent and reversible manner, with a 50% inhibitory concentration value (IC(50)) of (1.24 ± 0.07) mmol/L for current activated by 100 μmol/L ATP. (2) Mg(2+) (1 mmol/L) shifted the dose-response curve for I(ATP) right-downward without changing the EC(50), but reduced the maximal current (E(max)) by (42.0 ± 2.1)%. (3) After being preincubated with Mg(2+) for 80 s, the inhibitory effect of the Mg(2+) on I(ATP) reached the maximum. (4) The inhibition of Mg(2+) on I(ATP) was independent of membrane potential from -120 mV to +60 mV. (5) Compared with the current activated by 100 μmol/L ATP in the wild-type P2X4 receptors, mutant P2X4 D280Q responded to the application of 100 μmol/L ATP with a smaller current. The peak current was only (4.12 ± 0.15)% of that seen in wild-type receptors. Mutant P2X4 D280E responded to ATP stimulation with a current similar to that observed in cells expressing wild-type receptors. (6) When Asp280 was removed from P2X4, the current amplitude of I(ATP) was increased almost one-fold, and Mg(2+) with concentration ranging from 0.5-10 mmol/L did not affect the I(ATP) significantly. The results suggest that Mg(2+) inhibits I(ATP) mediated by P2X4 receptors non-competitively, reversibly, concentration-dependently, time-dependently and voltage-independently. The inhibitory effect of Mg(2+) might be realized by acting on the site Asp280 of the P2X4 receptors.
		                        		
		                        		
		                        		
		                        			Adenosine Triphosphate
		                        			;
		                        		
		                        			antagonists & inhibitors
		                        			;
		                        		
		                        			pharmacology
		                        			;
		                        		
		                        			Animals
		                        			;
		                        		
		                        			Female
		                        			;
		                        		
		                        			Magnesium
		                        			;
		                        		
		                        			pharmacology
		                        			;
		                        		
		                        			Membrane Potentials
		                        			;
		                        		
		                        			drug effects
		                        			;
		                        		
		                        			Oocytes
		                        			;
		                        		
		                        			metabolism
		                        			;
		                        		
		                        			physiology
		                        			;
		                        		
		                        			Patch-Clamp Techniques
		                        			;
		                        		
		                        			Rats
		                        			;
		                        		
		                        			Receptors, Purinergic P2X4
		                        			;
		                        		
		                        			genetics
		                        			;
		                        		
		                        			physiology
		                        			;
		                        		
		                        			Xenopus laevis
		                        			
		                        		
		                        	
            
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