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You-Yi Zhang

Publications and source records attributed to You-Yi Zhang.

At least 19 recordsLinked to original sources
PubMed2006

The transport of alpha(1A)-adrenergic receptor with 33-nm step size in live cells.

We used the technique of single particle tracking (SPT) with high tempo-spatial resolution to efficiently explore the route and mechanism for the transport of alpha(1A)-adrenergic receptor (alpha(1A)-AR) in real time in living cells. We found that the initial transport of alpha(1A)-AR in cells depended on actin filaments with the velocity of 0.2 microm/s and exhibited discrete 33-nm steps. It was noted that the step size, the rate constant, and the velocities were in accordance with the character of single myosin in vitro, implying that while transporting each endosome myosins did not work in the "tug-of-war" mode and that they did not adopt the strategy to boost up transporting speed by working coordinately. These results provided insight into the mechanism of GPCR transport in vivo.

Actins↗
PubMed2006

Phenylarsine oxide inhibited beta-adrenergic receptor-mediated IL-6 secretion: inhibition of cAMP accumulation and CREB activation in cardiac fibroblasts.

As we previously reported, cAMP and p38 MAPK instead of protein kinase A were involved in beta-adrenergic receptor (beta-AR)-mediated interleukin-6 (IL-6) production in mouse cardiac fibroblasts. Besides kinases, phosphatases may also be involved in IL-6 gene regulation. To study the role of protein tyrosine phosphatases (PTPs) in beta-AR-mediated IL-6 production, we selected the most widely used PTP inhibitor, phenylarsine oxide (PAO). We found that PAO dose-dependently inhibited the IL-6 release in response to beta-AR agonist isoproterenol (ISO) in mouse cardiac fibroblasts. This effect was probably due to the inhibition of PTPs, resulting in increased tyrosine phosphorylation, since genistein, an inhibitor of protein tyrosine kinases further potentiated ISO-induced IL-6 production and could partially reverse the inhibitory effect of PAO. PAO also significantly inhibited the IL-6 production by forskolin, an adenylyl cyclase (AC) activator. Furthermore, PAO dose-dependently inhibited the increased cAMP accumulation by either ISO or forskolin and suppressed the phosphorylation of CREB, an important transcriptional factor for IL-6 gene expression. But PAO did not affect the activation of p38 MAPK by ISO. Although PAO was also reported to inhibit NADPH oxidase, the inhibition of NADPH oxidase by its specific inhibitor, diphenylene iodonium (DPI) could not suppress beta-AR-mediated IL-6 production, suggesting that NADPH oxidase may not contribute to the inhibitory effect of PAO on IL-6 production. To our knowledge, this is the first report that PAO can inhibit ISO-induced IL-6 expression and CREB phosphorylation, demonstrating that PTPs may negatively regulate beta-AR-mediated IL-6 production. This study may also further our understanding of beta-AR signaling and provide potential therapeutic targets for the treatment of heart diseases.

Animals↗
PubMed2006

Expression and functional analysis of beta-adrenoceptor subtypes in rabbit submandibular gland.

beta-Adrenoceptors (beta-ARs) mediate important physiological functions in salivary glands. Here we investigated the expression and function of beta-AR subtypes in rabbit submandibular gland (SMG). Both beta(1)- and beta(2)-ARs, but not beta(3)-AR, were strongly expressed in rabbit SMG. beta(1)-AR proteins were widely expressed in acinar and ductal cells whereas beta(2)-AR proteins were mainly detected in ductal cells. A [(3)H]-dihydroalprenolol binding assay revealed that beta-AR B(max) was 186+/-11.9 fmol/mg protein and K(d) was 2.71+/-0.23 nM. A competitive binding assay with CGP 20712A, a beta(1)-AR antagonist, indicated that the proportion of beta(1)-AR and beta(2)-AR was 71.9% and 28.1%, respectively. Gland perfusion with the beta-AR agonist isoproterenol induced a significant increase in saliva secretion which was abolished by pretreatment with the non-selective beta-AR antagonist propranolol. Pretreatment with beta(1)- or beta(2)-AR selective antagonists, CGP 20712A or ICI 118551, diminished isoproterenol-induced increase in saliva secretion by 71.2% and 28.8%, respectively. The expression of alpha-amylase mRNA was significantly stimulated by isoproterenol, which was eliminated by propranolol and CGP 20712A. Perfusion with isoproterenol decreased alpha-amylase protein storage in SMG and increased alpha-amylase activity in saliva. These alterations became less significant after pretreatment with propranolol and CGP 20712A. Our results suggest that both beta(1)- and beta(2)-ARs are expressed in rabbit SMG. beta(1)-AR is the predominant subtype and may play an important role in regulating saliva and alpha-amylase secretion.

Animals↗
PubMed2006

Noncanonical cAMP pathway and p38 MAPK mediate beta2-adrenergic receptor-induced IL-6 production in neonatal mouse cardiac fibroblasts.

We previously reported that cardiac fibroblasts, but not cardiomyocytes, are served as the predominant source of IL-6 after isoproterenol stimulation in mouse myocardium. The present study investigated the molecular mechanism of isoproterenol-mediated secretion of IL-6 in mouse cardiac fibroblasts. Treatment of cells with isoproterenol-induced a time-dependent accumulation of IL-6, which was mediated by beta(2)-adrenergic receptor (AR), the preponderant beta-AR subtype in cardiac fibroblasts. Isoproterenol-induced secretion of IL-6 was mainly mediated by Gs-AC-cAMP signaling cascade and could be negatively regulated by Gi and PI3K. Surprisingly, the effect of cAMP was independent of protein kinase A and the exchange protein directly activated by cAMP (Epac)-Rap1 pathway and suggests the existence of a novel cAMP-dependent mechanism. p38 MAPK inhibitor SB203580, but not extracellular regulated protein kinase inhibitor, abrogated isoproterenol-induced IL-6 release in cardiac fibroblasts and mouse myocardium. Interestingly, p38 MAPK could also be positively regulated by Gs-AC-cAMP but negatively regulated by Gi-PI3K pathway. Finally, multiple transcription factors (AP-1, C/EBP, NF-kappaB and CREB) regulating the IL-6 gene are activated in response to isoproterenol stimulation, which may provide essential linkage between upstream cAMP-p38 MAPK signaling cascade and downstream IL-6 gene transcription. The present results suggest that beta(2)-AR mediates IL-6 production through a noncanonical cAMP responsible pathway and p38 MAPK.

Adrenergic beta-Agonists↗
PubMed2005

AICAR stimulates IL-6 production via p38 MAPK in cardiac fibroblasts in adult mice: a possible role for AMPK.

Though known as a sensor of energy balance, AMP-activated protein kinase (AMPK) was recently shown to limit damage and apoptotic activity and contribute to the late preconditioning in heart. Interleukin-6 was also reported to involve in anti-apoptosis and cardio-protection in myocardium. Interestingly, both AMPK activity and IL-6 level were increased in response to ischemia, hypertrophy and oxidative stress. To determine whether AMPK activation will promote IL-6 production, cardiac fibroblasts (CFs) from mice were incubated with AMPK activator, 5-aminoimidazole-4-carboxamide-1-4-ribofuranoside (AICAR). The results demonstrated that AICAR time and dose-dependently stimulated IL-6 production by ELISA and immunofluorescence. Pretreatment with p38 mitogen-activated protein kinase (MAPK) inhibitor blocked AICAR-induced IL-6 production; furthermore, AICAR-activated p38 MAPK phosphorylation by Western blot. To confirm that the increase in IL-6 production is ascribed to AMPK activation, we used another known AMPK activator, metformin. It also dose-dependently potentiated IL-6 production in CFs, and this potentiation could be reversed by p38 MAPK inhibitor. In conclusion, AMPK activation promoted IL-6 production in CFs via p38 MAPK-dependent pathway.

AMP-Activated Protein Kinases↗
PubMed2005

[Redistribution of three alpha1-adrenergic receptor subtypes in the stably transfected HEK 293A cells upon agonist stimulation.].

To investigate the subcellular distribution of three alpha(1)-adrenergic receptor subtypes and their internalization and trafficking upon agonist stimulation in human embryonic kidney (HEK) 293A cell line, saturation radioligand binding assay, laser confocal imaging, and Western blot were applied to examine the distribution and changes in localization of three alpha(1)-AR subtypes in transfected HEK 293A cells prior to and after treatment with phenylephrine. The results are as follows: (1) The transfection efficiency was over 90%and was equal among three alpha(1)-AR subtypes. alpha(1B ) -AR expression in cell membrane was the highest, and alpha(1D ) -AR was the lowest, as determined by (125)I-BE2254 binding assay, however, K(d)s were not significantly different among the three receptor subtypes. (2) Without agonist stimulation, alpha(1A ) -AR was detected not only on the cell surface but also in the cytosol, alpha(1B ) -AR was predominantly located on the cell surface, whereas alpha(1D ) -AR was mostly detected in the cytosol. (3) After 1 h of stimulation with phenylephrine, as observed using confocal microscope, less alpha(1A)- and alpha(1B ) -AR were detected on the cell surface but more in the cytosol. The change was more remarkable in alpha(1B)-AR than that in alpha(1A)-AR, whereas no change of distribution was detected in alpha(1D)-AR in response to phenylephrine. However, when examined by Western blot, no change in distribution was detected in alpha(1A)- and alpha(1D)-AR, only alpha(1B)-AR showed the same change as that shown in confocal imaging. It is suggested that the characteristics of localization and changes of distribution are different among three alpha(1)-AR subtypes in HEK293A cells upon phenylephrine stimulation.

English Abstract↗
PubMed2005

Optical detection of single molecules in living cells.

Single molecule detection is a technology of studying biomolecules with high spatial and temporal resolution. By exploiting recent technical advances, we are able to observe, detect, even manipulate individual molecules and study their conformational changes and dynamic behaviors. New information can be obtained from the single molecule research, which is otherwise hidden or averaged out. In recent years, the development of single molecule detection techniques has opened up a new era of life science. In this review, we introduce the advances of the techniques for detecting single molecules in cell biology and review the development of single molecule detection in living cells.

Animals↗
PubMed2004

[Comparison of changes in left ventricular gene expression profiles from different cardiac hypertrophy models in rats].

To get insights into the principles of gene expression changes during cardiac hypertrophy, three rat cardiac hypertrophy models were prepared, i.e., suprarenal abdominal aortic stenosis (SRS), arterial-vein fistula (AVF) and continuous jugular vein infusion of norepinephrine (NEi). The cardiac function and structure were analyzed by echocardiograph as well as histological examination. Total RNA of left ventricles was extracted and gene expression profiles were analyzed by cDNA microarray. SRS and NEi induced concentric cardiac hypertrophy and AVF induced eccentric hypertrophy in rats, among which NEi caused obvious cardiac fibrosis. The changes of gene expression profiles were compared comprehensively across different pathologic cardiac hypertrophy models. While gene expression profiles of different cardiac hypertrophy models compared with pairs, parts of the genes involved were found overlapped, and mostly the gene expression changed in the same direction between two models, but some of them changed in the opposite directions. Expression levels of 19 genes were found changed across all cardiac hypertrophy models, and genes relatively regulated in a specific model was also found when comparison of all the three models was carried out. Novel clues for further study might derive from the results mentioned above, and some genes might be the marker genes of cardiac hypertrophy or the targets of therapy.

Animals↗
PubMed2004

[Effects of beta-adrenoceptor activation on metabolism in neonatal rat cardiomyocytes].

The aim of the present study was to investigate the effects of beta-adrenergic receptor (beta-AR) activation on metabolism in cultured neonatal rat cardiomyocytes. The protein synthesis and total protein content of cardiomyocytes were determined by [(3)H]-leucine incorporation and BCA protein content assay. Cardiomyocyte glucose uptake was measured by [(3)H]-2-deoxy-D-glucose uptake analysis. Adenosine monophosphate activated protein kinase (AMPK) phosphorylation was detected by Western blot. The results showed that sustained stimulation with isoproterenol (ISO), a beta-adrenoceptor agonist, had no effect on [(3)H]-leucine incorporation and total protein content in cardiomyocytes. With beta-AR activation by ISO or NE (pretreated with a selective blocker of the alpha(1)-adrenoceptor prazosin) for 48 h, both the glucose uptake and AMPK phosphorylation increased significantly compared with unstimulated cardiomyocytes. These results suggest that although sustained beta-AR activation has no effect on cardiomyocyte protein metabolism, glucose uptake and AMPK activity are increased significantly. The role of these beta-AR activation-induced changes in cardiac hypertrophy remains to be further investigated.

AMP-Activated Protein Kinases↗
PubMed2004

beta-Adrenoceptors potentiate alpha1-adrenoceptor-mediated inotropic response in rat left atria.

AIM: To investigate whether stimulation of beta-adrenoceptor (AR) and its subtypes augment alpha1-AR-evoked positive inotropic response and inositol phosphate (InsP) accumulation in isolated rat left atria. METHODS: Inotropic response was determined by contractile function experiment in isolated electrically driven rat left atria. 3H-InsP accumulations were measured by 3H-inositol incorporation and column chromatography. RESULTS: (1) Stimulation of alpha1-AR by phenylephrine (PE) or norepinephrine (NE) in the presence of propranolol (Prop) evoked positive inotropic response and 3H-InsP accumulations, while stimulation of beta-AR by isoprenaline (ISO) or NE in the presence of phentolamine (Phen) only evoked positive inotropic response, but not 3H-InsP accumulations. (2) Simultaneous stimulation of alpha1- and beta-AR by NE or ISO plus PE significantly shifted the concentration-dependent inotropic response curves and 3H-InsP accumulation curves to the left and upward compared with individual alpha1-AR stimulation by PE or NE in the presence of Prop. (3) In the presence of ICI118551 (selective beta2-AR antagonist) or CGP12177 (selective beta1-AR antagonist), stimulation of either beta1- or beta2-AR did not change alpha1-AR-evoked inotropic response and 3H-InsP accumulations. CONCLUSION: Stimulation of beta1-AR and beta2-AR potentiates alpha1-AR-mediated positive inotropic response and InsP accumulation in isolated rat left atria.

Adrenergic alpha-1 Receptor Agonists↗
PubMed2003

[Binding between alpha 1A-adrenergic receptor and segment of bone morphogenetic protein-1 in human embryonic cell 293].

Using matchmaker yeast two-hybrid system, it has been demonstrated that there exists an interaction between the cellular C terminal of alpha(1A)-adrenergic receptor (alpha(1A)-AR) and a segment of bone morphogenetic protein-1 (BMP-1). In the present study binding between the two proteins was further determined in human embryonic cell 293 (HEK293), a mammalian expression system. Mammalian expression vector PCP3HA was constructed by PCR and consisted of segments of BMP-1 cDNA, and vector PDT-alpha(1A) consisted of the full-length cDNA of human alpha(1A)-AR. They were transfected to HEK293 cells and examined by Western blot. alpha(1A)-AR and the segment of BMP-1 could be detected in the lysis of transfected cells. Then binding between alpha(1A)-AR and the segment of BMP-1 in HEK293 cell was determined by enzyme-linked immunosorbent assays (ELISA) and co-immunoprecipitation. In ELISA experiment, the ELISA microwell plate was first coated with anti-FLAG M2 antibody, which recognizes the FLAG-tagged alpha(1A)-AR, then the cell lysis, anti-HA rabbit polyclonal antibody and HRP conjugated anti-rabbit antibody were added in turn. The OD(490) values among the control group, PDT-alpha(1A) transfection group and PCP3HA transfection group, exhibited no significant difference (0.034+/-0.027, 0.042+/-0.019, 0.030+/-0.0096), but the OD(490) values of PDT-alpha(1A) and PCP3HA co-transfection group (0.57+/-0.12) were significantly higher than those of the other groups (P<0.001, respectively). In co-immunoprecipitation experiments, HEK293 cells expressing alpha(1A)-AR or/and segment of BMP-1 were lysed and incubated with anti-FLAG M2 antibody, then the immunoprecipitation pellet was immunoblotted with either the HRP conjugated anti-FLAG antibody or the anti-HA antibody, which recognizes the HA-tagged segment of BMP-1. Segment of BMP-1 was present in the pellet immunoprecipitation of PDT-alpha(1A) and PCP3HA co-transfected group. In conclusion, the results indicate that alpha(1A)-AR and the segment of BMP-1 are present in the same complex in HEK293 cells.

Adrenergic alpha-Agonists↗
PubMed2003

[Isoproterenol-induced activation of MAPK, NFkappaB and JAK/STAT pathway in mouse myocardium].

This study was aimed to determine the in vivo signal transduction pathway responsible for isoproterenol (ISO)-induced cardiac hypertrophy or remodeling. Mice were treated with ISO (15 mg/kg body weight) or vehicle by intraperitoneal injection (i.p.). Activation of mitogen-activted protein kinase (MAPK), NF-kappaB and JAK/STAT pathway in the left ventricular myocardium was measured by Western blot analysis. ISO significantly activated MAPK (ERK1/2 and p38) at early phase (5 min); biphasic activation of NF-kappaB was observed in our in vivo study; and ISO caused a delayed STAT3 activation (at 60 to 240 min) in mouse myocardium. Taken together, these results indicate that ISO activates these signal transduction pathways in different time course.

Animals↗
PubMed2003

[Expression of beta2-adrenergic receptor and its effect on the proliferation of neonatal rat cardiac fibroblasts].

The expression of beta-adrenergic receptor subtypes and its effect on neonatal rat cardiac fibroblast proliferation were investigated by radioligand binding assay and [(3)H]-thymidine incorporation analysis, respectively. The results indicated that there was no significant difference in the beta-adrenergic receptor density (B(max)) and affinity (K(D)) between cardiomyocytes and cardiac fibroblasts. The [(125)I]-pindolol competitive inhibition curves (ICI 118551 and CGP 20712A) were significantly better fit in a one-site model in membrane preparation of cardiac fibroblasts. In cultured cardiac fibroblasts, 0.1 micromol/L isoproterenol-induced [(3)H]-thymidine incorporation was completely inhibited by a selective beta (2)-AR antagonist ICI 118551, or a non-selective beta-AR antagonist propranolol, but not by CGP 20712A, a selective beta(1)-AR antagonist. These results suggest that isoproterenol-induced cardiac fibroblast proliferation is mediated by beta(2)-AR, the preponderant beta-AR subtype in cardiac fibroblasts.

Animals↗
PubMed2003

[Alterations of Axin protein expression during cardiac remodeling in rats].

The purpose of the present study was to observe the expression of Axin protein during cardiac remodeling in rats. Cardiac remodeling animal models were prepared with the methods of jugular venous norepinephrine (NE)-infusion or arterial-vein fistula (AVF). The ultrasonic parameters of rat hearts were recorded before sacrifice. The expressions of Axin protein were determined by Western blot in rat hearts from different remodeling models as well as cultured cardiac fibroblasts from adult rats. Cardiac concentric hypertrophy and fibrosis was induced by 3-day jugular vein infusion of NE in rats. The expression of Axin in the left ventricles increased significantly compared with that of the control group. Cardiac eccentric hypertrophy without fibrosis was induced by A-V fistula for one week in rats, and no change in Axin protein expression in the left ventricles was observed. In cultured adult rat cardiac fibroblasts, NE treatment for 24 h increased significantly the Axin protein level. It is therefore concluded that Axin protein was expressed in rat heart and increased significantly in left ventricles during NE-induced rat cardiac remodeling, which may be relevant to cardiac fibrosis.

Animals↗
PubMed2003

[Changes in the gene expression profile of the left heart ventricle during growth in the rat].

Wistar rats of 8, 10 and 12-week-old were chosen for study of the relationship between cardiac growth and its gene expression profile changes during maturation. The ultrasonic parameters of rat hearts were recorded before sacrifice, then total RNA of left ventricle were extracted and gene expression profiles were analyzed by cDNA microarray. During growth from 8 weeks to 12 weeks, the body weight increased by 45.5% (287+/-13 g vs 197+/-10 g), and the increment in the first two-week period was equal to that of the second two-week period. The mass of left ventricle and the posterior wall thickness increased by 27.7% (0.60+/-0.03 g vs 0.47+/-0.02 g) and 23.6% (2.04+/-0.04 mm vs 1.65+/-0.13 mm), respectively, and their increment in the first two-week period was much more than that in the second one. Meanwhile, the gene expression profile of the left ventricle changed significantly, which involved cellular structure, metabolism, oxidative stress, signal transduction, etc. Compared with the 8-week-old rats, these genes were mostly up-regulated in 10-week-old rats, while for 12-week-old rats, the gene expression profile of the left ventricle recovered to the pattern of 8-week-old rats again on the whole. These results suggest that the relationship between the changes in cardiac function and gene expression profile can be analyzed comprehensively with the technique of microarray, and that the changes in gene expression profile of the left ventricle during rat maturation adapt to the physiological growth of heart, which is of benefit for keeping the metabolism balance between materials and energy.

Animals↗
PubMed2003

Functional alpha1-adrenergic receptor subtypes in human right gastroepiploic artery.

AIM: To study the functional alpha1-adrenergic receptor (alpha1-AR) subtypes in human right gastroepiploic artery (RGA). METHODS: The effects of alpha2-AR, alpha1-AR, and alpha1-AR subtype selective antagonists on norepinephrine (NE)-induced vasoconstriction in isolated human RGA were observed by contractile function experiment. RESULTS: Cumulative concentration-response curves for NE were competitively antagonized in RGA by alpha2-AR selective antagonist yohimbine (pA2 6.82+/-0.28, slope 1.12+/-0.40),alpha1-AR selective antagonist prazosin (pA2 9.77+/-0.22, slope 0.90+/-0.22),alpha1A-AR selective antagonists RS17053 (pA2 8.42+/-0.20, slope 0.93+/-0.20) and 5-MU (pA2 8.42+/-0.22, slope 0.88+/-0.18),alpha1D-AR selective antagonist BMY7378 (pA2 6.84+/-0.32, slope 1.05+/-0.17), and alpha1A-,alpha1B-AR selective antagonist WB4101 (pA2 8.88+/-0.20, slope 1.15+/-0.16). The correlation coefficients between these pA2 values of alpha1-AR selective antagonists with pKi values of which obtained from alpha1A-, alpha1B- and alpha1D-AR cloned cells are 0.95, 0.82, and 0.42. After the vessels were pretreated by chlorethylclonidine (CEC), an alpha1B- and alpha1D-AR irreversible alkylating agent, the pD2 values were changed from 5.9+/-0.5 to 5.6+/-0.6 and the maximal contraction was changed from (8.9+/-3.2) g to (8.0+/-3.2) g, respectively. The difference was not significant. CONCLUSION: In human RGA, the contraction response is mainly mediated by alpha1-AR, of which alpha1A-AR plays an important role, whereas alpha1B- and alpha1D-AR are not involved in the contraction response.

Adrenergic alpha-1 Receptor Antagonists↗
PubMed2003

Characterization of cAMP accumulation mediated by three alpha1-adrenoceptor subtypes in HEK293 cells.

AIM: To investigate the characterization of cAMP response mediated by alpha1-adrenoceptor (alpha1-AR) subtypes in HEK293 cells. METHODS: (1) Full-length cDNA encoding three alpha1-AR subtypes were transfected into HEK293 cells by the calcium phosphate precipitation method, respectively. (2) The densities of alpha1-AR subtypes expressed in HEK293 cells were measured by radioligand binding assay. (3) cAMP accumulation was measured by [3H]adenine prelabeling method. RESULTS: (1) Activation of each of three subtypes resulted in an increase of cAMP accumulation in HEK293 cells in a dose-dependent manner, which was inhibited by selective alpha1-AR antagonist prazosin. (2) Comparing the pharmacological property, the maximal responses of alpha1A-AR to agonists were the most potent, while the sensitivity of alpha1-AR subtypes to norepinephrine (NE) was the highest. CONCLUSION: Each of three alpha1-AR subtypes can mediate cAMP accumulation in HEK293 cell line, and there are differences in pharmacological property.

Cell Line↗