NAC transcription factor SlNOR-like1 plays a dual regulatory role in tomato fruit cuticle formation.

The plant cuticle is an important protective barrier on the plant surface, constructed mainly by polymerized cutin matrix and a complex wax mixture. Although the pathway of plant cuticle biosynthesis has been clarified, knowledge of the transcriptional regulation network underlying fruit cuticle formation remains limited. In the present work, we discovered that tomato fruits of the NAC transcription factor SlNOR-like1 knockout mutants (nor-like1) produced by CRISPR/Cas9 [clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein 9] displayed reduced cutin deposition and cuticle thickness, with a microcracking phenotype, while wax accumulation was promoted. Further research revealed that SlNOR-like1 promotes cutin deposition by binding to the promoters of glycerol-3-phosphate acyltransferase6 (SlGPAT6; a key gene for cutin monomer formation) and CUTIN DEFICIENT2 (SlCD2; a positive regulator of cutin production) to activate their expression. Meanwhile, SlNOR-like1 inhibits wax accumulation, acting as a transcriptional repressor by targeting wax biosynthesis, and transport-related genes 3-ketoacyl-CoA synthase1 (SlKCS1), ECERIFERUM 1-2 (SlCER1-2), SlWAX2, and glycosylphosphatidylinositol-anchored lipid transfer protein 1-like (SlLTPG1-like). In conclusion, SlNOR-like1 executes a dual regulatory effect on tomato fruit cuticle development. Our results provide a new model for the transcriptional regulation of fruit cuticle formation.

Transcription factor SlBEL2 interferes with GOLDEN2-LIKE and influences green shoulder formation in tomato fruits.

Chloroplasts play a crucial role in plant growth and fruit quality. However, the molecular mechanisms of chloroplast development are still poorly understood in fruits. In this study, we investigated the role of the transcription factor SlBEL2 (BEL1-LIKE HOMEODOMAIN 2) in fruit of Solanum lycopersicum (tomato). Phenotypic analysis of SlBEL2 overexpression (OE-SlBEL2) and SlBEL2 knockout (KO-SlBEL2) plants revealed that SlBEL2 has the function of inhibiting green shoulder formation in tomato fruits by affecting the development of fruit chloroplasts. Transcriptome profiling revealed that the expression of chloroplast-related genes such as SlGLK2 and SlLHCB1 changed significantly in the fruit of OE-SlBEL2 and KO-SlBEL2 plants. Further analysis showed that SlBEL2 could not only bind to the promoter of SlGLK2 to inhibit its transcription, but also interacted with the SlGLK2 protein to inhibit the transcriptional activity of SlGLK2 and its downstream target genes. SlGLK2 knockout (KO-SlGLK2) plants exhibited a complete absence of the green shoulder, which was consistent with the fruit phenotype of OE-SlBEL2 plants. SlBEL2 showed an expression gradient in fruits, in contrast with that reported for SlGLK2. In conclusion, our study reveals that SlBEL2 affects the formation of green shoulder in tomato fruits by negatively regulating the gradient expression of SlGLK2, thus providing new insights into the molecular mechanism of fruit green shoulder formation.

[The establishment and identification of GPx-1(P198L) gene systemic expression transgenic mice].

OBJECTIVE: To generate systemic expression human cellular glutathione peroxidase-1 (GPx-1) (198Leu) transgenic mice model in order to investigate the functional variants in GPx-1 gene in oxidative stress-related diseases. METHODS: After linearization with BamnH I and Acc I, the transgenic construct GPx-1 (198Leu) was microinjected into the zygotes of C57BL/6J mice to generate transgenic mice, whose genotype was detected by PCR with specific primers. The GPx-1 gene expression profile was determined by Western blotting. RESULTS: 13 transgenic founder mice were successfully generated. Western blotting result showed that the protein expression level of 4 transgenic mice in hearts were higher than that of wild type mice. CONCLUSION: Human GPx-1PSL transgenic mice was successfully established. This kind of animal model is of significance for making further researches on oxidative stress-related diseases.

An irregular approach of right atrial lead placement in a patient with persistent left superior vena cava and concomitant agenesis of the right-sided superior vena cava.

Persistent left superior vena cava (PLSVC) is the most common venous anomaly of the thorax. It could lead to catheter malplacement and even vascular injuries. We describe an unusual way to deliver a right atrial (RA) endocardial pacing lead in a 61-year-old female with a PLSVC concomitant agenesis of the right-sided SVC. After failed attempts with the standard procedure, we placed the RA lead tip in the PLSVC near the right auricle. The pacemaker worked well after one and 17 months of follow-up. We conclude that when placement of the RA lead fails, the PLSVC near the right auricle could be a next choice in the RA lead placement in patients with PLSVC concomitant agenesis of the right-sided SVC.

Oxidized low-density lipoprotein induces inflammatory responses in cultured human mast cells via Toll-like receptor 4.

BACKGROUND/AIMS: Oxidized low-density lipoprotein (ox-LDL) is a powerful atherogen. Toll-like receptor 4 (TLR4) has a pathophysiological role in regulating inflammatory responses and atherosclerosis. Mast cells can infiltrate into the atheromatous plaque and secrete various pro-inflammatory cytokines, which significantly amplify the atherogenic processes and promote plaque vulnerability. Small interfering RNA (siRNA) is an effective method to silence the target genes. We evaluated whether ox-LDL-induced inflammation depended in part on the activation of TLR4-dependent signaling pathways in a cultured human mast cell line (HMC-1). METHOD: HMC-1 cells were cultured, and treated with ox-LDL, TLR4-specific siRNA, or inhibitors of phosphorylation of mitogen-activated protein kinase (MAPKs), and nuclear factor-κB (NF-κB), a critical mediator of inflammation. The expression of monocyte chemoattractant protein-1 (MCP-1), tumor necrosis factor-α (TNF-α) and interleukin 6 (IL-6) was measured subsequently. RESULTS: Ox-LDL increased the expression of TLR4 and secretion of MCP-1, TNF-α and IL-6. Moreover, ox-LDL stimulated the translocation of NF-κB, from the cytoplasm to nucleus. Additionally, phosphorylation of MAPK was greatly increased. These ox-LDL-induced alterations were significantly attenuated by pretreatment with TLR4-specific siRNA. CONCLUSION: Ox-LDL induced inflammatory responses in cultured HMC-1 cells including NF-κB nuclear translocation and phosphorylation of MAPKs, a process mediated in part by TLR4.

Curcumin inhibits LPS-induced inflammation in rat vascular smooth muscle cells in vitro via ROS-relative TLR4-MAPK/NF-κB pathways.

AIM: To investigate whether curcumin (Cur) suppressed lipopolysaccharide (LPS)-induced inflammation in vascular smooth muscle cells (VSMCs) of rats, and to determine its molecular mechanisms. METHODS: Primary rat VSMCs were treated with LPS (1 µg/L) and Cur (5, 10, or 30 µmol/L) for 24 h. The levels of MCP-1, TNF-α, and iNOS were measured using ELISA and real-time RT-PCR. NO level was analyzed with the Griess reaction. Western-blotting was used to detect the activation of TLR4, MAPKs, IκBα, NF-κB p65, and the p47(phox) subunit of NADPH oxidase in the cells. RESULTS: Treatment of VSMCs with LPS dramatically increased expression of inflammatory cytokines MCP-1 and TNF-α, expression of TLR4 and iNOS, and NO production. LPS also significantly increased phosphorylation of IκBα, nuclear translocation of NF-κB (p65) and phosphorylation of MAPKs in VSMCs. Furthermore, LPS significantly increased production of intracellular ROS, and decreased expression of p47(phox) subunit of NADPH oxidase. Pretreatment with Cur concentration-dependently attenuated all the aberrant changes in LPS-treated VSMCs. The LPS-induced overexpression of MCP-1 and TNF-α, and NO production were attenuated by pretreatment with the ERK inhibitor PD98059, the p38 MAPK inhibitor SB203580, the NF-κB inhibitor PDTC or anti-TLR4 antibody, but not with the JNK inhibitor SP600125. CONCLUSION: Cur suppresses LPS-induced overexpression of inflammatory mediators in VSMCs in vitro via inhibiting the TLR4-MAPK/NF-κB pathways, partly due to block of NADPH-mediated intracellular ROS production.

[Two-dimensional gel electrophoresis map of serum proteins in patients with chronic Keshan disease].

OBJECTIVE: To identify the different serum proteins expressed in patients with Keshan disease (KD). METHODS: Two-dimensional gel electrophoresis (2-DE) was performed with serum samples from the patients with chronic KD and healthy controls to separate serum proteins. The gels were stained by sliver and scanned by Umax scanner. The data were analyzed by ImageMaster 2D software. KD related proteins were identified through searching the ExPASy SWISS-2DPAGE database. RESULTS: Stable two-dimensional gel electrophoresis maps were established for serum samples of KD patients and healthy controls. A total of 808 and 814 protein spots were observed in KD patients and healthy controls, respectively. The two maps had 96.5475% identical protein spots and 44 differentially expressed protein spots. Eleven protein spots were expressed exclusively in KD patients and 12 protein spots only appeared in healthy controls. About 21 proteins were expressed in both groups but varied in quantities (14 proteins were over-expressed by more than 3 times and 7 proteins were under-expressed by more than 3 times in KD patients, P < 0.01). Among the 353 protein spots matched with the ExPASy-SWISS-2DPAGE databank, No. 1177 protein appeared in the KD patient was found to have the closest match with P02774 2-D0004T6 known as vitamin D binding protein (VDBP). CONCLUSION: There is a significant difference in serum protein expression between KD patients and normal people. VDBP might play a role in cardiac muscle damage via inflammatory immune reactions.

Effect of peroxisome proliferator activated receptor γ agonist on angiotensin converting enzyme 2 mRNA expression in monocyte-derived macrophages of essential hypertensive patients.

OBJECTIVE: To study the effect of peroxisome proliferator activated receptor γ (PPAR-γ) agonist on the angiotensin converting enzyme 2 (ACE2) mRNA expression in monocyte-derived macrophages of essential hypertensive patients. METHODS: Totally 57 essential hypertensive patients were randomly divided into three groups: conventional treatment group (n=18), telmisartan group (n=19), and benazepril group (n=20); 20 patients with normal blood pressure were also selected as the control group. Monocyte-derived macrophages were isolated from blood samples of patients in all four groups. The expression of ACE2 mRNA in monocyte-derived macrophages was detected by RT-PCR before treatment and 4 and 12 weeks after treatment. RESULTS: Four and 12 weeks after treatment, the systolic pressure and diastolic pressure of telmisartan group and benazepril group were significantly lower than that of the conventional treatment group (all P<0.01), and the systolic pressure and diastolic pressure of telmisartan group were significantly lower than that of the benazepril group(both P<0.01) .The expression of ACE2 mRNA in monocyte-derived macrophages were significantly lower in essential hypertensive patients than that in control group (P<0.01). After having been treated for 4 weeks and 12 weeks, the expression of ACE2 mRNA in monocyte-derived macrophages of hypertensive patients in telmisartan and benazepril groups were significantly higher than that in conventional treatment group (all P<0.01), and the expression of ACE2 mRNA in telmisartan group was significantly higher than that in benazepril group (both P<0.01). CONCLUSION: PPAR-γ agonist could increase the ACE2 mRNA expression in monocyte-derived macrophages of essential hypertensive patients.

Generation and application of anti-ouabain IgY antibodies.

Ouabain is a bioactive hapten and is very difficult to be accurately quantified because of the lack of useful reagents. Furthermore, where ouabain is produced in the adrenal glands has not been identified. In this study, ouabain-BSA was generated for immunizing the laying hens to generate ouabain-specific IgY antibodies in chicken eggs. The anti-ouabain IgY antibodies were detected in eggs 1 week after the last immunization and their concentrations increased with time. The highest concentrations of anti-ouabain IgY antibodies reached at 1:10,240 for ELISA 5 weeks after immunization and maintained for 4 weeks in chicken eggs. Following PEG precipitation, an average of 8.5 mg of anti-ouabain IgY antibodies with a purity of 87.6% was achieved from a single egg. Further analysis revealed that the anti-ouabain IgY antibodies had little immunoreactivity to hydrocortisone, dexamethasone, cedilanid, and digoxin, indicating their high specificity, and the purified IgY antibodies effectively detected endogenous ouabain in the cytoplasm of cells predominately in the zona reticularis of rat and human adrenal glands, indicating their high immunoreactivity. Given that IgY has an unique structure and bioactive features, the generated anti-ouabain IgY antibodies may be used as a new reagent for accurately quantifying ouabain in biological studies.

Activation of peroxisome proliferator-activated receptor-γ downregulates soluble epoxide hydrolase in cardiomyocytes.

1. The antidiabetic agents, thiazolidinediones (TZD), ligands for peroxisome proliferator-activated receptor-γ (PPARγ), have been reported to reduce cardiac hypertrophy. However, the underlying mechanism is still elusive. 2. We previously reported that soluble epoxide hydrolase (sEH) was specifically upregulated by angiotensin-II (AngII), which directly mediated AngII-induced cardiac hypertrophy. In the present study, we examined the role of sEH in PPARγ inhibiting AngII-induced cardiac hypertrophy. 3. The protein level of sEH was elevated in the left ventricle of AngII-infused Sprague-Dawley rats. Administration of the TZD rosiglitazone decreased this induction. In vitro, AngII upregulated the expression of sEH and hypertrophy markers, including atrial natriuretic factor and ß-myosin heavy chain, in rat neonatal cardiomyocytes and H9c2 cells, which was attenuated by rosiglitazone and pioglitazone. An elevated level of sEH was also found in the left ventricle of heterozygous PPARγ-deficient mice. The effect of TZD on sEH level could be reversed by treatment with the PPARγ antagonists, GW9662 and BADGE, which suggests PPARγ activation. In elucidating the mechanisms by which PPARγ inhibited AngII-induced sEH expression, we found that rosiglitazone inhibited AngII-induced sEH promoter activity in H9c2 cells. In contrast, the activity of the human sEH 3'UTR was not affected by AngII and TZD. 4. Our results suggest that the protective role of PPARγ activation in AngII-induced cardiac hypertrophy is, at least in part, through downregulating sEH.

Tannic acid alleviates lipopolysaccharide­induced H9C2 cell apoptosis by suppressing reactive oxygen species­mediated endoplasmic reticulum stress.

Sepsis­induced myocardial dysfunction is one of the features of multiple organ dysfunction in sepsis, which is associated with extremely high mortality and is characterized by impaired myocardial compliance. To date, there are few effective treatment options available to cure sepsis. Tannic acid (TA) is reportedly protective during sepsis; however, the underlying mechanisms by which TA protects against septic heart injury remain elusive. The present study investigated the potential effects and underlying mechanisms of TA in alleviating lipopolysaccharide (LPS)­induced H9C2 cardiomyocyte cell apoptosis. H9C2 cells were treated with LPS (15 µg/ml), TA (10 µM) and TA + LPS; control cells were treated with medium only. Apoptosis was measured using flow cytometry, reverse transcription­quantitative PCR (RT­qPCR) and western blot analysis. Additionally, the levels of cellular reactive oxygen species (ROS), malondialdehyde and nicotinamide adenine dinucleotide phosphate were evaluated. Western blotting and RT­qPCR were also employed to detect the expression levels of endoplasmic reticulum (ER) stress­associated functional proteins. The present findings demonstrated that TA reduced the degree of LPS­induced H9C2 cell injury, including inhibition of ROS production and ER stress (ERS)­associated apoptosis. ERS­associated functional proteins, including activating transcription factor 6, protein kinase­like ER kinase, inositol­requiring enzyme 1, spliced X box­binding protein 1 and C/EBP­homologous protein were suppressed in response to TA treatment. Furthermore, the expression levels of ERS­associated apoptotic proteins, including c­Jun N­terminal kinase, Bax, cytochrome c, caspase­3, caspase­12 and caspase­9 were reduced following treatment with TA. Additionally, the protective effects of TA on LPS­induced H9C2 cells were partially inhibited following treatment with the ROS inhibitor N­acetylcysteine, which demonstrated that ROS mediated ERS­associated apoptosis and TA was able to decrease ROS­mediated ERS­associated apoptosis. Collectively, the present findings demonstrated that the protective effects of TA against LPS­induced H9C2 cell apoptosis may be associated with the amelioration of ROS­mediated ERS. These findings may assist the development of potential novel therapeutic methods to inhibit the progression of myocardial cell injury.

Expression of key ion channels in the rat cardiac conduction system by laser capture microdissection and quantitative real-time PCR.

The objective of this study was to investigate the molecular basis of the inferior nodal extension (INE) in the atrioventricular junctional area that accounts for arrhythmias. The INE was separated from the adult rat heart by laser capture microdissection. The mRNA expression of ion channels was detected by quantitative real-time PCR. Hierarchical clustering was used to demonstrate clustering of expression of genes in sections. The mRNA expression of HCN4, Ca(v)3.1 and Ca(v)3.2 was high in the INE, atrioventricular node and sino-atrial node, and that of Ca(v)3.2 high in Purkinje fibres. Although the expression of HCN1 and Ca(v)1.3 was low in the rat heart, it was relatively higher in the INE, atrioventricular node and sino-atrial node than in right atrial and right ventricular (working) myocytes. Both HCN2 and Ca(v)1.2 were expressed at higher levels in working myocytes than in nodal tissues and in the INE. Hierarchical clustering analysis demonstrated that the expression of the HCN and calcium channels in INE was similar to that in the slow-response automatic cells and different from that in working myocytes and Purkinje fibres. The expression of HCN and calcium channels in the INE of the adult rat heart is similar to that of slow-response automatic cells and provides a substrate for automatic phase 4 depolarization in cells.

[Polymorphisms in the glutathione peroxidase-1 gene associated with increased risk of Keshan disease].

OBJECTIVE: To assess the association of blood selenium and polymorphism of glutathione peroxidase-1 (GPx-1) genes in patients with Keshan Disease (KD) and provide genetic evidence for KD susceptibility. METHODS: The levels of whole blood selenium and the activity of GPx-1 were measured with spectrophotometric and enzymatic method among 71 KD patients and 290 controls (including 78 internal controls and 212 external controls). The genotype of GPx-1 at 198 site was analyzed by sequencing and PCR-RFLP. The functions of two GPx-1 variants were studied by rat neonatal cardiomyocytes transfection and expression plasmid. RESULTS: Blood level of selenium in KD patients was (0.8 ± 0.2) µmol/L, the internal controls' was (0.9 ± 0.2) µmol/L, and the external controls' was (1.2 ± 0.2) µmol/L (F = 4.888, P < 0.001).GPx-1 activity of KD patients was (73.0 ± 12.6) × 10(-10)U/RBC, internal controls' was (80.9 ± 9.2) × 10(-10)U/RBC, and external controls' was (115.8 ± 21.1) × 10(-10)U/RBC (F = 5.324, P < 0.001). Those of KD patients were significantly lower than controls. The polymorphism (Pro198Leu) of GPx-1 were identified; the frequency of Pro198Leu of KD patients was 21.1%, the frequency of controls was 10.7% (χ(2) = 5.588, P = 0.018). The level of blood selenium in variant subgroup (Pro198Leu or Leu198Leu) was (0.9 ± 0.2) µmol/L, and its in non-variant subgroup was (1.1 ± 0.3) µmol/L (t = 3.183, P < 0.01); The GPx-1 activity in variant subgroup was (86.1 ± 23.0) × 10(-10)U/RBC, and its in non-variant subgroup was (101.8 ± 25.9) × 10(-10)U/RBC (t = 5.784, P < 0.01). Further analysis revealed a synergistic-multiplicative interaction between presence of GPx-1 codon198 alleles and low blood selenium level. Over-expression of GPx-1 (198Leu) in rat cardiomyocytes caused 30% lower enzyme activity and less response to increasing concentrations of selenium than with over-expression of GPx-1 (198Pro). CONCLUSION: Low blood selenium in carriers with the 198Leu-susceptible genotype of GPx-1 is associated with low GPx-1 activity, synergistic-multiplicative interaction was found between these two factors. And these two factors may increase the risk of KD.

Puerarin protects against myocardial ischemia/reperfusion injury by inhibiting inflammation and the NLRP3 inflammasome: The role of the SIRT1/NF-κB pathway.

AIMS: The purpose of this study was to investigate the protective effects of puerarin and elucidate the underlying mechanisms of puerarin in myocardial ischemia/reperfusion (MI/R) injury. MAIN METHODS: C57BL/6 mice were exposed to puerarin (100 mg/kg) with or without the SIRT1 inhibitor nicotinamide (500 mg/kg) and then subjected to MI/R operation. Myocardial infarct size, serum creatine kinase-MB (CK-MB) activity, apoptotic cell death, and cardiac structure and function were examined to evaluate MI/R injury. RT-PCR and western blotting were used to determine the inflammatory response and inflammasome activation, as well as activation of SIRT1/NF-κB pathway. RESULTS: Puerarin significantly reduced myocardial infarct size, serum CK-MB activity, and apoptotic cell death, and improved cardiac structural damage and dysfunction. Moreover, puerarin notably decreased the mRNA and protein levels of TNF-α, IL-6, and IL-1ß, indicating that puerarin attenuated MI/R-induced inflammation. Furthermore, puerarin markedly decreased the protein levels of Ac-NF-κB, NLRP3, cleaved caspase-1, cleaved IL-1ß, and cleaved IL-18 and increased the protein level of SIRT1. More importantly, the SIRT1 inhibitor nicotinamide prevented these puerarin-induced cardioprotective effects and regulation of the SIRT1/NF-κB pathway, as well as the NLRP3 inflammasome activation. CONCLUSION: Puerarin protected against MI/R injury by inhibiting inflammatory responses probably via the SIRT1/NF-κB pathway, and inhibition of the NLRP3 inflammasome was also involved in puerarin-induced cardioprotective effects. These results suggest that puerarin may be a novel candidate for the treatment of ischemic heart disease.

[Electrophysiologic characteristics of Ito in myocytes from cardiac Koch triangle].

OBJECTIVE: To explore the electrophysiologic characteristics of Ito in myocytes from cardiac Koch triangle. METHODS: Patch clamp technique was employed to investigate the I-V and D-V relation, steady-state activation and inactivation kinetics of Ito from myocytes in Koch triangle of rabbit hearts. RESULTS: (1) The maximum peak current (pA) and peak current density (pA/pF) at +20 mV in PC (pacing cell), TC (transitonal cell) alpha,beta, AC (atrial cell) and PL (purkinje-like cell) cells were different from each other (P < 0. 05); The cells also had different current density (P < 0.05) except between TCalpha, TCbeta and PL cells (P > 0.05). (2) The half activation potential (V(mIto1/2), mV) of steady state activation among PC, TCalpha, TCbeta, AC and PL were significantly different (P < 0.05); The paired comparison between TCalpha and TCbeta, AC and PL, and TCbeta and PC showed significant difference (P < 0.05); but the differences between TCa and PC, TCbeta and AC, and TCbeta and PL were not significant (P > 0.05). (3) The half inactivation potential (V5(hIto1/2), mV) of steady state inactivation between TCalpha and PC, TCa and PL, TCbeta and PC, and TCbeta and PL demonstrated significant differences(P < 0.05). The differences of K(hIto) between TCalpha and TCbeta, PC and PL, TCbeta and PC, and AC and PL were significant (P < 0.05). CONCLUSIONS: Ito of cardiac cells from Koch triangle in rabbit hearts are heterogeneous, but relatively specified and distributed in different groups.

[Expression and purification of truncated fragment of extracellular segment of sodium pump alpha3 subunit in Escherichia coli by in-fusion technology].

OBJECTIVE: To construct prokaryotic expression system for expressing, purifying and identifying truncated fragment of extra-cellular segment of sodium pump alpha3 subunit with pGEX-6P-1 GST gene fusion system in Escherichia coli by in-fusion technology. METHODS: According to the conservative sequence of M1-M2 and M3-M4 extra-cellular gene fragments of sodium pump a3 subunit, which published in GenBank, a serial of primers and gene fragments was designed, and directly synthesized to fuse the above two gene fragments. The fusion gene was fused with gene-specific primers by PCR, and then fusion gene fragment was fused into the single stranded homology regions of vector pGEX-6P-1 by in-fusion cloning to construct recombinant vector pGEX-Trf-alpha3 (Truncated fragment of extracellular segment of sodium pump alpha3 subunit, Trf-alpha3). After DH10bac was transferred with it, the pGEX-Trf-alpha3 plasmid was purified and identified by PCR and sequenced. Then the recombinant plasmid pGEX-Trf-alpha3 was expressed in E. coli BL21 cells, inducted by IPTG. GST-Trf-alpha3 fusion protein was purified with Glutathione Sepharose 4B purifying system and analyzed by SDS-PAGE. RESULTS: The results of PCR and sequencing demonstrated that the M1-M2 and M3-M4 extra-cellular gene was inserted in plasmid pGEX-6P-1 vector successfully. And the sequence was correct. Protein sequence analysis showed that the GST-Trf-alpha3 fusion protein was consisted of 262 amino-acid residues. Relative molecular mass in theory was 33.22 X 10(3). The amount of recombinant protein was 10% of the total bacteria protein. The soluble fusion protein was about 80.8%. After affinity purification, the purity of GST-Trf-alpha3 fusion protein was over 95%. There was some extent binding activity between GST-Trf-alpha3 fusion protein and ouabain, but the activity was very low. CONCLUSION: Prokaryotic expression system for expressing truncated fragment of extra-cellular segment of sodium pump alpha3 subunit with pGEX-6P-1 GST gene fusion system in Escherichia coli by in-fusion technology had been constructed. The purified method had also established. High purified GST-Trf-alpha3 fusion protein was obtained. These have found the foundation of further study on its biological function and potential pharmacology function.

Sodium current kinetics of transitional myocytes in Koch triangle of rabbit hearts.

BACKGROUND: Few studies have explored the inward sodium current (INa) kinetics of transitional cardiomyocytes. This study aimed to explore the kinetics of transitional cardiomyocytes types alpha and beta. METHODS: The whole-cell patch clamp technique was used to study the rapid INa of isolated transitional cardiomyocytes in the Koch triangle of rabbit hearts. RESULTS: Maximal amplitude and density of INa in type alpha and type beta was (-1627 +/- 288) pA (alpha), (-35.17 +/- 6.56) pA/pF (beta) and (-3845 +/- 467) pA (alpha), (-65.64 +/- 10.23) pA/pF (beta) (P < 0.05). Steady state activation curves of INa, fitted to a Boltzmann distribution for both types, were sigmoid in shape. Half activation voltage and slope factors did not significantly differ between types at (-43.46 +/- 0.85) mV (alpha), (-41.39 +/- 0.47) mV (beta) or (9.04 +/- 0.66) mV (alpha), (11.08 +/- 0.89) mV (beta). Steady state inactivation curves of INa, fitted to a Boltzmann distribution in both types were inverse "S" shape. Half inactivation voltage and slope factors were (-109.9 +/- 0.62) mV (alpha), (-107.5 +/- 0.49) mV (beta) and (11.78 +/- 0.36) mV (alpha), (11.57 +/- 0.27) mV(beta), (P > 0.05), but time constants of inactivation were significantly different at (1.10 +/- 0.19) mV (alpha) and (2.37 +/- 0.33) ms (beta), (P < 0.05). Time constants of recovery from inactivation of INa for both types were (122.16 +/- 27.43) mV (alpha) and (103.84 +/- 28.97) ms (beta) (P < 0.05). CONCLUSIONS: Transitional cardiomyocytes in rabbit hearts show a heterogeneous, voltage gated and time dependent fast inward sodium current. Types alpha and beta show the features of INa similar to those in slow- and fast-response myocytes, with probably better automaticity and conductivity, respectively.

[Activity identification of peptide containing rat sodium pump α2 subunit M1-M2 extramembrane fragment in vitro].

In order to explore the activity of a peptide containing rat sodium pump α2 subunit M1-M2 extramembrane fragment (RES2 derivative) in vitro, the peptide (Leu-Ala-Ala-Met-Glu-Asp-Glu-Pro-Ser-Asn-Asp-Asn-Gly-Gly-Gly-Ser) was synthesized by peptide synthesizer with Fmoc method and purified by high performance liquid chromatography (HPLC). Its binding activity was identified by radioligand-receptor binding assay (RRA) and its bioactivity was measured by erythrocyte (86)Rb uptake. The results of saturation binding experiment and competitive binding experiment showed that the synthesized RES2 derivative had the capability to bind to (3)H-ouabain. The dissociation constant (K(d)) was 38.46 nmol/L and IC(50) was 6.353 nmol/L. Erythrocyte (86)Rb uptake experiment showed that the RES2 derivative blocked the inhibitory effect of ouabain on the sodium pump on erythrocyte membrane in a dose-dependent manner. The results showed that the RES2 derivative is capable of binding to ouabain and improving the activity of sodium pump on erythrocyte membrane, suggesting that the RES2 derivative might become an effective antihypertensive drug in the future.

Arginine vasopressin stimulates proliferation of adult rat cardiac fibroblasts via protein kinase C-extracellular signal-regulated kinase 1/2 pathway.

Arginine vasopressin (AVP), a neurohormone and hemodynamic factor implicated in the pathophysiology of hypertension and congestive heart failure, can also act as a growth-stimulating factor. Our previous work demonstrated that AVP is a mitogen for neonatal rat cardiac fibroblasts (CFs). In the present study, we extended our investigations to adult rat CFs to explore whether AVP could induce adult rat CF proliferation and, if so, to identify the mechanism involved. Adult rat CFs were isolated, cultured and subjected to AVP treatment. DNA synthesis and cell cycle distribution were analyzed by [(3)H]-thymidine incorporation and flow cytometry. Cellular extracellular signal-regulated kinase 1/2 (ERK1/2) activity was measured by in vitro kinase assay using myelin basic protein (MBP) as a substrate. Protein expressions of total- and phospho-ERK1/2, p27(Kip1), cyclins D1, A, E were assessed by Western blot. The results showed that AVP stimulated DNA synthesis in adult rat CFs, and the effect was abolished by a V1 receptor antagonist, d(CH(2))(5)[Tyr(2)(Me), Arg(8)]-vasopressin (0.1 µmol/L), but not by a V2 receptor antagonist, desglycinamide-[d(CH(2))(5), D-Ile(2), Ile(4), Arg8]-vasopressin (0.1 µmol/L). AVP induced an activation of ERK1/2, which could be mimicked by the protein kinase C (PKC) activator, phorbol 12-myristate 13-acetate (PMA, 30 nmol/L, 5 min), but abolished by depletion of PKC via chronic PMA incubation (2.5 µmol/L, 24 h). In addition, AVP down-regulated protein expression of p27(Kip1), increased protein expressions of cyclins D1, A and E, and induced cell cycle progression from G(0)/G(1) into S stage. Inhibition of ERK1/2 activation by PD98059 (30 µmol/L) abolished the effect of AVP on DNA synthesis, protein expressions of p27(Kip1), cyclins D1, A and E as well as cell cycle progression. These results suggest that AVP is also a growth factor for adult rat CFs. The mitogenic effect of AVP is mediated via V1 receptors and PKC-ERK1/2 pathway. Moreover, AVP modulates the expressions of cell cycle regulatory proteins p27(Kip1) and cyclins D1, A and E, which lie downstream of ERK1/2 activation, and induces cell cycle progression in adult rat CFs.

Rosiglitazone inhibits angiotensin II-induced CTGF expression in vascular smooth muscle cells - role of PPAR-gamma in vascular fibrosis.

Angiotensin (Ang) II plays a pivotal role in vascular fibrosis, which leads to serious complications in hypertension and diabetes. Connective tissue growth factor (CTGF) is a potent profibrotic factor implicated in the Ang II-induced pathologic fibrosis process. PPAR-gamma activators thiazolidinediones have been recently reported to have beneficial vascular effects. However, their effects and related molecular mechanisms on extracellular matrix (ECM) turnover in vascular smooth muscle cells (VSMCs) are unknown. The present study evaluated the regulation of Ang II-induced CTGF, ECM production and cell growth by rosiglitazone in VSMCs. In aorta of Ang II-infused rats, CTGF expression was markedly increased, and type III collagen and fibronectin overexpression was observed. Cotreatment with rosiglitazone diminished these changes, whereas increased nuclear PPAR-gamma expression in VSMCs. In growth-arrested VSMCs, rosiglitazone attenuated the proliferation and apoptosis, increased PPAR-gamma production and activation, and reduced CTGF and ECM production in response to Ang II in a dose-dependent fashion. These inhibitory effects were attenuated by the pretreatment of cells with PPAR-gamma antagonist GW9662 or bisphenol A diglycidyl ether (BADGE). Furthermore, rosiglitazone inhibited Ang II-induced Smad2 production and phosphorylation but had no effect on transforming growth factor-beta(1) (TGF-beta(1)) expression. These results suggest that in Ang II-stimulated VSMCs, rosiglitazone caused an antiproliferative, antiapototic effect and reduces ECM production through mechanisms that include reducing CTGF expression, and a crosstalk between PPAR-gamma and Smad may be involved in the inhibitory effects of rosiglitazone. This novel finding suggests a role of PPAR-gamma activators in preventing Ang II-induced vascular fibrosis.