Changes of the myocardium energy metabolism and adenine nucleotide translocase activity in rats after hypoxic exposure

］AIM: To explore the changes of myocardial energy metabolism and adenine nucleotide translocase (ANT) activity in mitochondria in rats exposed to hypoxia. METHODS: Adult male Wistar rats were exposed to simulated high altitude at 5 000 m for control (0 d), 1 d, 5 d, 15 d, 30 d in hypobaric chamber. Myocardial mitochondria were isolated by centrifugation. Mitochondria respiratory function was measured by Clark oxygen electrode. The size of adenine nucleotides pool (ATP, ADP, AMP) in mitochondria were separated and measured by HPLC. ANT activity was measured by ［3H］-ADP incorporation. RESULTS: Compared to control, mitochondria state Ⅲ respiratory (ST3) and RCR decreased and ST4 increased sharply at 1 d, 5 d and 15 d, ST3 still lower than that in control at 30 d, while RCR level restored. ATP contents and ANT activity decreased at 1 d and 5 d, then restored to control level at 15 d, then decreased again at 30 d. CONCLUSION: The inhibition of mitochondria respiratory function is the main reason that makes ATP contents decrease during hypoxic exposure. ANT activity and ATP content change cooperatively.     

中国园艺学会2012年学术年会暨庆祝《园艺学报》创刊50周年—园艺学进展论坛征文通知

"中国园艺学会2012年学术年会暨庆祝《园艺学报》创刊50周年—园艺学进展论坛"将于2012年10月在西安举行,即日起征集:①研究论文摘要,②有关园艺学进展的综述文章。经审查合格的摘要和综述将分别收入"中国园艺学会2012年学术年会论文摘要集"和"庆祝《园艺学报》创刊50周年—园艺学进展论坛专辑",并于会前以     

Calcineurin signal transduction pathway involves in cardiomyocyte hypertrophy induced by prostaglandin F2α

AIM: To study the role of prostaglandin F₂α (PGF₂α) in cardiac hypertrophy and its relation with calcineurin (CaN) signal transduction pathway in vitro. METHODS: The cultured neonatal rat cardiomyocyte was used to observe the hypertrophic effect of PGF2α, and the hypertrophic response was assayed by measuring the cell diameter, protein content and atrial natriuretic factor (ANF) mRNA expression. For mechanism studies, the intracellular free calcium concentration (［Ca²⁺］_i) in cultured cardiomyocytes was measured by using Fura-2/AM as a fluorescent indicator. ANF and CaN mRNA expressions, and the expressions of CaN and its downstream effectors, NFAT₃ and GATA₄ proteins were assayed by RT-PCR and Western blotting, respectively.RESULTS: In cultured cardiomyocytes, PGF₂α induced profound hypertrophic morphology change, the significant increase in cell diameter and protein content in a concentration-dependent manner compared with those in vehicle control (P<0.01). The same result was found in measuring the ［Ca²⁺］_i in cardiomyocytes (P<0.01). PGF₂α at concentration of 10-7 mol/L significantly promoted ANF and CaN mRNA expressions and the protein expressions of CaN/NFAT₃/GATA₄ compared with those in the vehicle control (P<0.05). Cyclosporin A, a CaN inhibitor, markedly inhibited the myocyte hypertrophy (P<0.01), reduced the increased ［Ca²⁺］_i(P<0.01) and decreased the expressions of CaN mRNA and CaN/NFAT₃/GATA₄ proteins (P<0.05) compared with those of only PGF₂α　10^-7 mol/L treatment. CONCLUSION: Cardiomyocyte hypertrophy induced by PGF2α may be, at least in part, mediated by CaN signal transduction pathway activated by increasing ［Ca²⁺］_i.     

Activation of Akt signal pathway cascades in kidney tissue in murine chronic graft-versus-host disease lupus nephritis and its regulation by prednisone

AIM:To examine whether Akt signal pathway proteins, including Akt, NF-κB and IκBα, are activated in kidney tissue of murine chronic graft-versus-host disease (GvHD) lupus nephritis in vivo, and whether prednisone suppresses activation of them.METHODS:Akt activity and phosphorylated IκBα were detected by Western-blot. Activation of NF-κB was detected by electropheretic mobility shift assay (EMSA). RESULTS:Activity of Akt, NF-κB and phosphorylated IκBα were significantly increased in kidney tissue of murine chronic graft-versus-host disease (GvHD) in 8th week and 12th week after monocell injection, respectively. However, they were no significant elevation in 16th week, when compared with controls. Prednisone treatment significantly prevented the increase in serum anti-dsDNA antibody level, urinary protein excretion and glomerular cell proliferation in GvHD mice, indicating the beneficial effects of prednisone on this model. Prednisone also significantly suppressed the increase in the activities of glomerular Akt, NF-κB and phosphorylated IκBα. CONCLUSION:This study provides the first evidence of marked increase in glomerular Akt-NF-κB signal pathway activities in murine chronic graft-versus-host disease lupus nephritis. The beneficial effect of prednisone on this lupus nephritis model may be partially mediated by the suppression of abnormal Akt- NF-κB activation.     

Hydrogen sulfide suppresses the increase in reactive oxygen species in neurons induced by angiotensin II via ERK1/2 signal pathway

AIM: To investigate the effect of hydrogen sulfide (H₂S) on the reactive oxygen species (ROS) level in medullary neurons induced by angiotensin II (Ang II). METHODS: Primarily cultured rat medullary neurons were divided into 5 groups as follows: control group, Ang II group, sodium hydrosulfide(NaHS) group, NaHS with Ang II group, and PD98059 (an inhibitor of p-ERK1/2) with Ang II group. ROS production was measured with dihydroethidium (DHE) staining. The expression of p-ERK1/2 and ERK1/2 was determined by Western blotting. The activity of neurons was detected by CCK-8 assay. RESULTS: Ang II at concentration of 100 nmol/L significantly increased ROS level in the neurons, but the effect was inhibited by NaHS at concentrations of 50~200 μmol/L, while NaHS alone had no influence on the ROS level in neurons. Additionally, PD98059 also depressed the ROS level in neurons induced by Ang II. Furthermore, the enhanced expression of p-ERK1/2 in the neurons induced by Ang II was significantly reduced by NaHS. CONCLUSION: H₂S remarkably inhibits the ROS level in the neurons induced by Ang II via activation of MAPK signal pathways, especially p-ERK1/2, indicating that H₂S rescues neurons from oxidative stress through declining the enhanced expression of p-ERK1/2.     

Inhibition of tyrosinase gene expression by antisense nucleotide in murine B16 melanoma cells

AIM: To inhibit the expression of tyrosinase gene in murine B16 melanoma cells by antisense nucleotide. METHODS: The antisense recombinant pcDNA3.1(-)-tyr was constructed and was used to infect murine B16 melanoma cells for expression of tyr antisense nucleotide. The effect of antisense nucleotide of tyr on the expression of tyr gene was detected by determination of the activity of tyrosinase and of the production of melanin, Dopa staining and electronic microscope. RESULTS: The tyr antisense recombinant was successfully constructed and injected into murine B16 melanoma cell. The activity of tyrosinase in B16 cells infected with pcDNA3.1 (-)-tyr decreased to 0.0498±0.0036, compared to the tyrosinase activity of 0.0916±0.0132 in the control cells without treatment (P<0.01). The results of Dopa staining and electronic microscopy showed that the production of melanin also decreased significantly compared with control B16 cells. CONCLUSION: tyr antisense nucleotide significantly inhibits the expression of tyr gene in murine B16 melanoma cells.     

Role of G-protein-coupled receptor kinases in cell migration and signal transduction

G-protein-coupled receptor kinases (GRKs) are a family of serine/threonine protein kinases. The investigators pay much attention to the roles of GRKs in the signal transduction through G-protein-coupled receptors (GPCRs) with arrestin ever since a long time ago. Due to the physiological and pathological observations with the methods of deletion or overexpression, GRKs are considered as new drug targets. The kinases play a role in the pathogenesis of hypertension and cell migration through GPCRs and Hedgehog signaling pathways. As the development of research techniques, especially bioluminescence resonance energy transfer (BRET) and fluorescence resonance energy transfer (FRET), the special mechanism of GRKs for GPCRs is more evident. In this review, we discuss the recent achievement in the roles of GRKs signaling and the related newest research techniques.     

Effect of SAPK/JNK signal pathway on neuronal apoptosis in cerebral infarction rats

AIM: To investigate the molecular mechanism of neuronal apoptosis by observing the changes of key proteins in SAPK/JNK and Bcl-2/Bax signal pathways after brain infarction. METHODS: The cortical infarction was induced by photochemistry, namely photothrombotic cortical injury (PCI). Thirty-six Sprague-Dawley rats were randomly divided into 2 groups: PCI group and sham-operated group. The ipsilesional cortex was harvested for histomorphometry and transmission electron microscopy 7 days after PCI. Some key proteins including p-JNK1, p-JNK2, p-c-Jun, p-ATF-2, total JNK1, total JNK2, Bcl-2 and Bax were detected by Western blotting analysis.RESULTS: The cortical infarction in rats was successfully induced by photochemistry. The apoptosis of neurons in cortex was more obvious in PCI group than that in sham-operated group 7 days after PCI. The levels of p-JNK1, p-JNK2, p-c-Jun and p-ATF-2 in PCI group were significantly higher than those in sham-operated group, whereas the ratio of Bcl-2/Bax was significantly lower(P<0.05). CONCLUSION: Apoptosis is a major contributor to neuronal loss induced by cerebral hypoxia-ischemia for a long period after cortical infarction. The process is related to some apoptotic proteins such as Bcl-2/Bax and the SAPK/JNK signal pathways activated by ischemic injury.     

Significance of somatostatin receptor 2 expression in the murine liver tissue during carcinogenesis

AIM：To study the expression and distribution of somatostatin receptor 2 (SSTR2) during carcinogenesis of hepatocellular carcinoma (HCC) and to evaluate the role of SSTR2 in the carcinogenesis of HCC.METHODS：Experimental HCC model was induced in SD rats using EDNA.SSTR2 mRNA and protein expression were detected by RT-PCR and immunohistochemistry.SSTR2 expression in different tissues at different periods of carcinogenesis were compared.RESULTS：HCC nodule developed after 8 weeks of administration of EDNA.Semi-quantitative analysis showed that SSTR2-mRNA expression in cirrhotic liver tissue at 8 weeks of induction was significantly higher than that in normal liver tissue (1.794±0.212 vs 0.950±0.138,P<0.05).As induction prolonged,SSTR2-mRNA expression increased,and reached its peak level of 2.053±0.169.Then,it decreased gradually.At 22 weeks,SSTR2-mRNA expression decreased to 1.468±0.107,which was significantly lower than the values at 8 weeks and 16 weeks (P<0.05).SSTR2-mRNA in HCC tissue was at low expression level with an average of 1.219±0.249.SSTR2 protein expression was mainly at cytosol and membrane.The change of SSTR2 protein expression in different tissue was consistent with the change of mRNA expression.CONCLUSION：SSTR2 expression was increased at early stage of cirrhosis.At the late stage of cirrhosis and occurrence of HCC,SSTR2 expression was significantly decreased.Down-regulation of SSTR2 may contribute to the carcinogenesis and progression of HCC.     

PERK signal pathway is involved in hypoxia-induced endoplasmic reti-culum stress and apoptosis in cultured cardiac myocytes

AIM:To investigate the role of endoplasmic reticulum(ER) stress in the process of hypoxia-induced neonatal rat myocardial injury through PERK signal pathway. METHODS:Neonatal rat cardiac myocytes were randomly divided into control group and hypoxia 1 h, 4 h, 8 h, 12 h and 24 h groups. Cell viability was evaluated by determining the intracellular content of ATP. Apoptosis was measured by high-content analysis(HCA) cell imaging system. The protein levels of GRP78, calreticulin, p-PERK, p-eIF2α, ATF4 and CHOP were detected by Western blotting at different time points. The primary cultured neonatal rat cardiac myocytes were treated with an agonist of PERK pathway salubrinal and the cell apoptosis was observed under hypoxia. RESULTS:In the early phase, hypoxia induced an increase in the expression of calreticulin and GPR78. In the middle phase of hypoxia, the levels of p-PERK, p-eIF2α and ATF4 were increased. In the later phase of hypoxia, increased CHOP level was also observed. Salubrinal effectively protected the cardiac myocytes from hypoxic injury. CONCLUSION:Hypoxia activates ER stress in cardiac myocytes and also activates PERK signal pathway. PERK signaling protects cardiac myocytes from hypoxic damage in the early stage and triggers apoptosis of the cells in the later phase.     

Role of Akt signal pathway in inhibition of neuronal apoptosis by Chinese medicine Zuogui pill in adult rats treated with monosodium glutamate

AIM: To explore the role of Akt signal pathway in apoptosis of neural cells in adult rats treated with Zuogui Pill, a Chinese medicine. METHODS: Flowcytometry and Western blotting methods were used to investigate the changes of cellular apoptosis rate and Akt signal pathway. RESULTS: Monosodium glutamate (MSG) could increase cellular apoptosis rate and significantly restrained the phosphorylation of Akt (Ser473) and Akt (Thr308), and markedly increased the levels of phospho-FKHR (ser256), GSK-3β (Ser9) and PTEN. Zuogui Pill partly inhibited the above effects of MSG. CONCLUSION: Zuogui pill effectively inhibits the neural apoptosis induced by MSG, and Akt pathway is involved in the neuronal protection of Zuogui pill.     

Role of Toll-like receptor 4/MAPKs pathway on monocyte chemoattractant protein-1 secretion induced by oxidized low density lipoprotein in vascular smooth muscle cells

AIM: To investigate the role of Toll-like receptor 4/MAPKs pathway on the secretion of monocyte chemoattractant protein-1 (MCP-1) induced by oxidized low density lipoprotein (ox-LDL) in the vascular smooth muscle cells (VSMCs). METHODS: mRNA and protein expressions of MCP-1 in VSMCs stimulated with oxidized low density lipoprotein were determined by RT-PCR and ELISA, respectively. The phosphorylated forms of ERK1/2 and p38MAPK were determined by Western blotting. TLR4 neutralizing antibodies (a specific TLR4 inhibitor), PD98059 (ERK1/2 specific inhibitor), SB23015 (p38MAPK specific inhibitor) and SP600125 (JNK specific inhibitor) were used to investigate the underlying mechanisms. RESULTS: The mRNA and protein expressions of MCP-1 in VSMCs were up-regulated by ox-LDL (P<0.05), while those were inhibited by TLR4 neutralizing antibodies, PD98059 or SB23015 (P<0.05), but not by SP600125 (P>0.05). TLR4 had regulatory effect on the phosphorylation of ERK1/2 and p38MAPK. CONCLUSION: ox-LDL is an endogenous ligand of TLR4. The secretion of MCP-1 induced by ox-LDL in VSMCs is at least in part via TLR4/ERK1/2 and TLR4/p38MAPKs pathways.     

Effects of hypoxia-inducible factor-1 signal pathway on proliferation in hypoxic pulmonary artery smooth muscle cells

AIM: To investigate the effect of hypoxia on the proliferation and apoptosis of pulmonary artery smooth muscle cells (PASMC); and to evaluate the role of hypoxia-inducible factor-1α(HIF-1α), iNOS, P-ERK1/2 protein expression in hypoxic pulmonary hypertension (HPH) pathogenesis.METHODS: Cultured rat PASMC were divided into normoxic group; hypoxic group; hypoxia+ADM(adrenomedulin) group, hypoxia+L-NAME(iNOS inhibitor) group; hypoxia+PD98059 group. Proliferation was investigated by MTT and PCNA. Apoptosis was examined by flow-cytometry. Westen blotting was used to measure protein expression of HIF-1α, P-ERK1/2 and iNOS. RESULTS: (1) A value of 24 h-hypoxia was significantly higher than that in the normoxic group (P<0.01). In the hypoxia+PD98059 group, ADM was significantly lower than that in hypoxia group, whereas A value of the hypoxia+L-NAME was significantly higher than that in hypoxic group and normoxic group (P<0.01). (2) PCNA was positive in PASMC after 24 h hypoxia (P<0.01). PD98059, ADM inhibited the expression of PCNA significantly (P<0.01), whereas L-NAME increased the expression of PCNA significantly (P<0.01). (3) Apoptosis index was not significantly difference among the different groups (P>0.05). (4) HIF-1α, iNOS and P-ERK1/2 expression was poorly positive in normoxic group, positive after hypoxia for 4h (P<0.01), reaching its peak at 8 h hypoxia (P<0.01), HIF-1α, P-ERK1/2 expression declined after 24 h hypoxia. L-NAME promoted the expression of HIF-1α, PD98059 inhibited the expression of HIF-1α, iNOS and P-ERK1/2 partly. ADM inhibited the expression of HIF-1α partly, promoted the expression of iNOS. CONCLUSION: (1) Hypoxia stimulates the proliferation of PASMC, and has no obvious effects on the apoptosis of PASMC. (2) HIF-1 plays an importent role in the proliferation of hypoxic PASMC.     

Changes of canonical Wnt signaling pathway in brains of rats with autism induced by prenatal exposure to valproic acid

AIM：To investigate the roles of the canonical Wnt pathway in autism. METHODS：Using an autistic model induced by prenatal exposure to valproic acid (VPA), we detected the expression of the signaling molecules of the canonical Wnt pathway in the prefrontal cortex (PFC) and hippocampus formation (HF) of autistic rats. The expression levels of glycogen synthase kinase 3β (GSK-3β), phosphorylated GSK-3β, β-catenin and phosphorylated β-catenin were observed by Western blotting. The mRNA expression of GSK-3β, β-catenin, c-Myc and cyclin D1 was assessed by semi-quantitative RT-PCR. RESULTS：The results of Western blotting showed that inactivated GSK-3β (Ser9) phosphorylation was significantly increased, and inhibitory β-catenin (Ser33/37/Thr41) phosphorylation was obviously decreased compared with control group. The results of RT-PCR showed that the mRNA levels of β-catenin, c-Myc and cyclin D1 increased, and GSK-3β was significantly enhanced in VPA-exposed rats compared with the controls. CONCLUSION：Increased activity of canonical Wnt pathway in the PFC and HF of autistic rats may contribute to the susceptibility to autism.