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Src homology phosphotyrosyl phosphatase 2 (SHP2) is a protein tyrosine phosphatase encoded by PTPN11, which catalyzes the dephosphorylation of protein tyrosine. As a convergence node, SHP2 mediates multiple signaling pathways such as rat sarcoma (RAS)-rapidly accelerated fibrosarcoma (RAF)-mitogen-activated extracellular signal-regulated kinase (MEK)-extracellular regulated protein kinases (ERK), phosphatidylinositol 3-kinase (PI3K)-serine/threonine kinase (AKT), janus kinase (JAK)-signal transducer and activator of transcription (STAT) and programmed death-1 (PD-1)/programmed cell death-ligand 1 (PD-L1). It can not only regulate the growth and proliferation of tumor cells, but also mediate the immune escape of tumor cells by influencing the tumor microenvironment. Given its dual biological functions in tumor immune regulation, SHP2 is a promising target for cancer immunotherapy. To date, several SHP2 allosteric inhibitors have been advanced into clinical trials for tumor immunotherapy with single or combination therapeutic strategies. Additionally, SHP2 activators also showed therapeutic potential in the field of tumor immune modulation. In this paper, we reviewed the dual function of SHP2 in both tumor and immune cells. Besides, the challenges and prospects of SHP2 modulators in cancer immunotherapy were also briefly discussed, aiming to explore new horizon of SHP2 modulators for tumor immunotherapy.
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ObjectiveTo explore the amelioration of cognitive dysfunction in diabetes mellitus （DM） by Jianpi Qinghua prescription （JPQH） based on type 2 diabetes （T2DM） model rats. MethodFifty healthy male Wistar rats of SPF grade were randomly divided into control group （n=10） and experimental group （n=40）. The rats in the control group were fed conventionally， while those in the experimental group were fed on a high-sugar， high-fat diet for six weeks and administered with streptozotocin （STZ） for the induction of the DM model. The model rats were randomly divided into model group， sitagliptin group （1.2 g·L-1）， pioglitazone group （0.8 g·L-1）， and JPQH group （1.3 g·mL-1）， with 10 rats in each group. After six weeks of drug intervention， the changes in body weight， blood glucose， and other related indexes of each group were recorded. Enzyme-linked immunosorbent assay （ELISA） was performed to detect the levels of tumor necrosis factor-α （TNF-α）， interleukin-1β （IL-1β）， and interleukin-6 （IL-6） in the peripheral blood and brain. The Morris water maze test was used to evaluate the cognitive function in rats. Hematoxylin-eosin （HE） staining was used to observe the pathological morphology of the hippocampal CA region. The amyloid β-protein 40 （Aβ40） level was detected by immunohistochemistry. The protein expression of t-tau and p-tau in hippocampal neurons of rats was detected by Western blot. ResultCompared with blank group， the body weight of model group was significantly decreased （P<0.05）， blood glucose level was significantly increased （P<0.01）， inflammatory cytokines TNF-α and IL-1β were increased （P<0.05）， learning and spatial ability were significantly decreased （P<0.01）， the arrangement of hippocampal cells was loose and disordered， and the intercellular space was significantly increased. The number of cells decreased significantly， and the expression of Aβ40 increased significantly. and increased t-tau and p-tau protein content in the hippocampus （P<0.01）. Compared with model group， the JPQH group showed reduced blood glucose （P<0.01）， decreased TNF-α and IL-1β levels in the peripheral blood and cerebrospinal fluid （P<0.05）， a downward trend of IL-6 without a statistical difference， improved learning and spatial memory ability （P<0.01）， densely arranged cells in the hippocampal CA1 area， increased cell number， reduced Aβ40 expression， and decreased p-tau protein expression （P<0.05）. ConclusionJPQH can prevent cognitive dysfunction in DM by reducing inflammatory factor levels， decreasing neurotoxicity caused by Aβ40 deposition， and inhibiting hyperphosphorylation of tau protein in DM rats.
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Pulmonary fibrosis (PF) is a chronic, progressive, fatal interstitial lung disease with limited available therapeutic strategies. We recently reported that the protein kinase glycogen synthase kinase-3
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A cascade of dramatic physiological events is linked to the sperm acrosome reaction and binding to the oocyte's zona pellucida during human sperm capacitation. However, structural and functional sperm changes during capacitation currently remain poorly defined. Here, we performed a multibiomarker approach based on the utilization of sperm concentration, motility, viability, morphology, acrosome reaction, tyrosine phosphorylation, DNA fragmentation, and lectin-binding sites to analyze the impact caused by swim-up selection times (uncapacitated, 1 h capacitated, and 4 h capacitated) on sperm function and structure in normozoospermic samples. We found that a 4 h swim-up capacitation increased sperm quality, because a large number of cells with normal morphology and lower DNA fragmentation rates were recovered. Furthermore, the long-term capacitation induced a higher percentage of cells with tyrosine phosphorylation of the principal piece as well as a redistribution of lectin-binding sites. Overall, the multivariate biomarkers analyzed showed a less variable distribution on spermatozoa recovered after 4 h capacitation than that with the shorter capacitation time. These findings stress the importance of capacitation time as a relevant factor in sperm quality with potential biological reproductive implications both for basic research and in assisted reproduction techniques.
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Protein phosphorylation is one of the main ways to activate protein bioactivity and make it participate in cell life activities. Researches have shown that approximately 30% of proteins in the human body are modified by phosphorylation at different levels and at different sites. If the protein phosphorylation modification level or site is abnormal, it will cause the occurrence and development of malignant tumors. Malignant tumors have always been a kind of diseases that endanger human life and health. According to statistics, as many as 18 million malignant tumors and more than 9.6 million deaths occur every year worldwide. With the continuous recognition on the abnormality of protein phosphorylation modification in tumorigenesis and development, the research and development of drugs for abnormality of protein phosphorylation modification has become a focus in the field of tumor therapy at present. Each traditional Chinese medicine(TCM) can be regarded as a natural molecular library, and it participates in the regulation of protein phosphorylation modification level with the advantages of multiple components and multiple targets, with slight side effect and low drug resistance, so TCM is one of the main sources of drug development for regulating protein phosphorylation modification levels. Through the search of multiple databases at home and abroad, it was found that certain monomers, parts extracted from TCM, single-TCM and TCM compounds can affect the tumor progression by regulating the level of protein phosphorylation and exert better anti-tumor effect. Based on the current research status of protein phosphorylation regulation by TCM at home and abroad, we found that TCM can inhibit tumor cell proliferation, invasion and metastasis, angiogenesis, and maintenance of stem cell stemness by regulating protein phosphorylation levels, and exert antitumor effects by promoting apoptosis. In order to clarify the molecular mechanism of TCM in regulating protein phosphorylation level and exerting antitumor effect, and provide evidences for the development and clinical application of antitumor TCM, the authors reviewed the mechanism of TCM in regulating protein phosphorylation level and exerting their antitumor effect from different ways in this paper.
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Objective To investigate the influence of blood glucose fluctuation on ser202 phosphorylation sites of tau protein( p-Tau) in hippocampus of diabetic rats; to explore the possible mechanism of blood glucose fluctuation impacting on tau protein hyperphosphorylation. Methods Healthy male Sprague Dawley rats were randomly divided into normal control group ( NC group ) and diabetes group. After diabetic rats model was established, all the diabetic rats were randomly divided into diabetic continuous hyperglycemia group (DC group) and diabetic blood glucose fluctuant group ( DF group). Rats in DF group were given glucose solution intraperitoneal injection twice at regular time everyday. 30 minutes after each intraperitoneal injection, insulin subcutaneously injections were given. Rats in the NC group and DC groups were given the same volume of saline subcutaneous injection. Specimens were collected in 8 weeks, the levels of p-Tau and total tau in rat hippocampus were detected by immunohistochemical staining and Western blotting. The immunoreactive positive products were analyzed by image analysis system. Glycogen synthase kinase-3β(GSK-3β) mRNA was detected by realtime PCR. Results (1) Blood glucose fluctuation of rats in DC and DF group were greater than NC group. And the mean blood glucose, standard deviation of mean blood glucose (SDBG), and large amplitude of glycemic excursion (LAGE) levels were increased significantly compared to NC group, the difference has statistical significance ( all P < 0. 05). Compared with DC group, SDBG and LAGE levels of DF group were higher (both P<0. 05). HbA1C and insulin levels were no difference (P>0. 05). (2) Compared with NC group, the hippocampal p-Tau level of DC group and DF group were increased (P < 0. 05 ); Compared with DC group, the hippocampal p-Tau expression of DF group was increased ( P <0. 05). Compared with DC group, a higher hippocampal GSK-3β mRNA level was found in DF group ( P <0. 05). Conclusions On the basis of diabetes animal model, giving glucose solution intraperitoneal injection and insulin subcutaneously injection 30 minutes later twice at regular time everyday could establish experimental model of diabetic blood glucose fluctuation. Blood glucose fluctuation may aggravate the diabetic rats hippocampal p-Tau. The possible mechanism seems to be an up regulation of the GSK-3β.
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Aim Bupivacaine is a kind of long-acting amide local anesthetics.This paper aims to explore the effects of bupivacaine on the short-circuit currents in human alveolar epithelial monolayers and study the possible mechanisms.Methods Short-circuit currents were recorded by ussing-chamber setup.Amiloride-sensitive currents were defined as the difference be-tween the total current and the amiloride-resistant cur-rent.ERK1 /2 phosphorylation protein levels were ana-lyzed by Western blot at 0,1 5,30 and 60 min after administration of 1 00 μmol·L -1 bupivacaine.Results Bupivacaine could inhibit the short-circuit currents in H441 monolayers dose-dependently,which could be inhibited by amiloride.Western blot analysis showed that bupivacaine increased the level of ERK1 /2 phos-phorylation.Conclusion These data demonstrate that bupivacaine can reduce the alveolar ion transport by in-hibiting the amiloride-sensitive currents,possibly by the enhancement of ERK1 /2 phosphorylation. The effects of alveolar fluid clearance following application of bupivacaine should be considered clinically when the patient is complicated with lung injury.
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Objective To investigate the influence of blood glucose fluctuation on ser202 phosphorylation sites of tau protein( p-Tau) in hippocampus of diabetic rats; to explore the possible mechanism of blood glucose fluctuation impacting on tau protein hyperphosphorylation. Methods Healthy male Sprague Dawley rats were randomly divided into normal control group ( NC group ) and diabetes group. After diabetic rats model was established, all the diabetic rats were randomly divided into diabetic continuous hyperglycemia group (DC group) and diabetic blood glucose fluctuant group ( DF group). Rats in DF group were given glucose solution intraperitoneal injection twice at regular time everyday. 30 minutes after each intraperitoneal injection, insulin subcutaneously injections were given. Rats in the NC group and DC groups were given the same volume of saline subcutaneous injection. Specimens were collected in 8 weeks, the levels of p-Tau and total tau in rat hippocampus were detected by immunohistochemical staining and Western blotting. The immunoreactive positive products were analyzed by image analysis system. Glycogen synthase kinase-3β(GSK-3β) mRNA was detected by realtime PCR. Results (1) Blood glucose fluctuation of rats in DC and DF group were greater than NC group. And the mean blood glucose, standard deviation of mean blood glucose (SDBG), and large amplitude of glycemic excursion (LAGE) levels were increased significantly compared to NC group, the difference has statistical significance ( all P < 0. 05). Compared with DC group, SDBG and LAGE levels of DF group were higher (both P<0. 05). HbA1C and insulin levels were no difference (P>0. 05). (2) Compared with NC group, the hippocampal p-Tau level of DC group and DF group were increased (P < 0. 05 ); Compared with DC group, the hippocampal p-Tau expression of DF group was increased ( P <0. 05). Compared with DC group, a higher hippocampal GSK-3β mRNA level was found in DF group ( P <0. 05). Conclusions On the basis of diabetes animal model, giving glucose solution intraperitoneal injection and insulin subcutaneously injection 30 minutes later twice at regular time everyday could establish experimental model of diabetic blood glucose fluctuation. Blood glucose fluctuation may aggravate the diabetic rats hippocampal p-Tau. The possible mechanism seems to be an up regulation of the GSK-3β.
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Alzheimer ’ s disease ( AD ) is characterized by pro-gressive loss of memory and other cognitive functions .With re-cent discoveries , activation of silent mating-type information reg-ulator 2 homolog 1 ( SIRT1 ) could attenuate the cognitive dys-function of AD via reducing amyloid-βaggregation and tau pro-tein phosphorylation , inhibiting inflammatory reaction , and regu-lating synaptic plasticity .This review aims to highlight the in-volvement of these new discoveries of SIRT 1, and Akt/protein kinase B(PKB) signaling pathways, for their potential therapeu-tic effect against AD .
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@#Objective To explore the effects of electroacupuncture at Shenting (DU24) and Baihui (DU20) on cognitive dysfunction after stroke. Methods Forty-five Sprague-Dawley rats were randomly divided into control group (n=15), model group (n=15) and electroacupuncture group (n=15). The latter two groups were occluded their middle cerebral artery for two hours and reperfused. The electroacupuncture group accepted electroacupuncture at Shenting and Baihui 24 hours after modeling for seven days. They were assessed with Morris water maze once a day since the second day of intervention. Their brains were stained with TTC staining to measure cerebral infarction volume after treatment, while the expression of cyclic AMP response element binding protein (CREB) and phosphorylation (p-CREB) in hippocampal CA1 area were detected with immunohistochemistry. Results The escape latency and swimming distance of place navigation shortened in the electroacupuncture group compared with those in the model group (P<0.05) from the fourth day of intervention. The number of cross platform of spatial probe increased (P<0.05). The infarction volume was less in the electroacupuncture group than in the model group (P< 0.05), with increased expression of CREB and p-CREB in hippocampal CA1 area (P<0.05). Conclusion Electroacupuncture at Shenting and Baihui can increase the expression of CREB and phosphorylation in hippocampal CA1 area in rats after cerebral ischemia-reperfusion, to protect the neurons from ischemia and improve the learning and memory function.
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Background Collapsin response mediator protein-2 (CRMP-2) can promote the growth of axons,but CRMP-2 occurs hyperphosphorylation under the induction of cyclin-dependent kinase-5 (CDK5) after central nervous system injury,which leads to the collapse of the growth cone and hinders the repair of nervous system.Being a central nervous system tissue,whether the expressions of CRMP-2 and its phosphorylated protein (p-CRMP-2) change after optic nerve injury are rarely studied.Objective This study was to investigate the dynamic changes of CRMP-2 and p-CRMP-2 expressions in injured optic nerve tissue.Methods Forty-eight 8-or 9-week-old BALB/c mice were randomly divided into the sham operation group and postoperative 3-,7-and 14-day group.Optic nerves were exposed and clamped at retrobulbar 2 mm for 10 seconds in the right eyes during the surgery in the postoperative 3-,7-and 14-day groups,and the same operation was performed except the clamp of optic nerve in the sham operation group.The optic nerve tissue was obtained from the eyes 3,7 and 14 days after surgery.The relative expression levels of CRMP-2 mRNA and CRMP-2,p-CRMP-2 and CDK5 proteins in the tissue were detected by real-time fluorescence quantitative PCR and Western blot,respectively.The use and care of the experimental animals complied with the Regulation for the Administration of Affair Concerning Experimental Animals of Third Military Medical University.Results No significant differences were found in the expression levels of CRMP-2 mRNA and CRMP-2 protein among the sham operation group and postoperative 3-,7-and 14-day groups (CRMP-2 mRNA:F =2.971,P =0.097;C RMP-2 protein:F=1.202,P =0.370).The relative expression levels of p-CRMP-2 protein in the optical nerve were 0.001±0.000,0.064±0.003,0.136±0.005 and 0.346±0.012,and those of CDK5 protein were 0.440±0.009,0.723±0.011,0.874±0.015 and 0.952±0.019 in the sham operation group and postoperative 3-,7-and 14-day groups respectively,showing statistically significant differences among them (p-CRMP-2:F=445.600,P ＜ 0.001;CDK5:F=186.600,P＜0.001),and the relative expression levels of p-CRMP-2 and CDK5 protein were evidently higher in the optical nerve tissue in the postoperative 3-,7-and 14-day groups than those in the sham operation group (all at P＜0.01).Conclusions There are not significant changes in the expression level of CRMP-2 in the BALB/c mice after optic nerve injury.However,the expression levels of p-CRMP-2 and CDK5 proteins are gradually upregulated as the extending of injured time.
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Objective To investigate the role of protein phosphorylation in Pseudomonas aeruginosa (P.aeruginosa) strains in response to stress triggered by mouse macrophages.Methods The strong cation exchange-immobilized metal affinity chromatography (SCX-IMAC) was performed to enrich phosphopeptides.The nanoscale liquid chromatography coupled to tandem mass spectrometry (nano LC-MS/MS) was carried out to identify and analyze phosphoproteome.Results Fourteen phosphopeptides from twelve proteins were identified within thirty-one phosphorylation sites on serine,threonine and tyrosine residues.Fifty percent of these phosphorylated proteins were membrane proteins,indicating that their phosphorylation modification was more critical for bacteria in response to the stress.In terms of biological process of Gene Ontology,these identified proteins were involved in stress response,iron transport,anaerobic respiration,response to hydrogen peroxide and signal transduction by phosphorylation,etc.Conclusion These phosphorylated proteins in P.aeruginosa strains are necessary for signal transduction and their response to harsh environment within the macrophages,such as iron limitation,hypoxia and oxidative stress.This study provides evidence for further investigation on virulence and pathogenesis of P.aeruginosa.
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Objective To investigate the genotypes of extended spectrum β-lactamases (ESBLs) and their carrying modes in Escherichia coli (E.coli) isolates,and to analyze the mechanism of protein phosphorylation and ESBLs gene expression induced by β-lactam antibiotics or inhibited by histidine kinase inhibitors.Methods The predominant genotypes of ESBLs (KPC,TEM,SHV and CTX-M) and their carrying modes were identified by PCR and sequencing analysis.E-test and micro-tube dilution method were applied to measure minimal inhibitory concentrations (MICs) and minimum bactericidal concentrations (MBCs).Immobilized metal ion affinity chromatography,bacterial protein phosphorylation detection kit and real-time fluorescent quantitation RT-PCR were performed to analyze the enhancing effects of 1/4 MIC penicillin or cefotaxime or the inhibitory effects of histidine kinase inhibitors (closantel,bromized or iodized methylimidazol) on protein phosphorylation and the expression of ESBLs at mRNA level in E.coli isolates.Results In 183 β-lactam antibiotics-resistant E.coli isolates,TEM and CTX-M genes (83.1％ and 77.1％) were highly expressed than other two ESBLs genes with a prevalent carrying mode of coexisting (65.0％) (P＜0.05).Penicillin or cefotaxime at 1/4 MIC induced the protein phosphorylation and promoted the expression of TEM,SHV and CTX-M at mRNA level (P＜0.05).Closantel (200 μmol),bromized methylimidazol (2 or 10 μmol) or iodized methylimidazol (20 or 50 μmol) could neither kill E.coli isolates nor inhibit their growth,but could inhibit the protein phosphorylation induced by above mentioned antibiotics and enhance the expression of ESBLs at mRNA level (P＜0.05).Moreover,the susceptibility of antibioticresistant E.coli strains to penicillin and cefotaxime were increased (P＜0.05).Conclusion TEM and CTX-M were the predominant genotypes of ESBLs carried by β-lactam antibiotics-resistant E.coli strains isolated from Zhejiang province,which were mostly found in a TEM plus CTX-M carrying mode.Sublethal dose of β-lactam antibiotics could up-regulate the expression of ESBLs genes in E.coli isolates via TCSS,but it could be inhibited by histidine kinase inhibitors.
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The present study was undertaken to examine calmodulin-dependent effect of thyroid hormones (THs) on synaptosomal protein phosphorylation in mature rat brain. Effect of L-triiodothyronine (L-T3) on in vitro protein phosphorylation was measured in a hypotonic lysate of synaptosomes prepared from adult male rat cerebral cortex, incubated in presence and absence of calcium ion (Ca2+) and calmodulin. L-T3 significantly enhanced incorporation of 32P into synaptosomal proteins as compared to basal level of phosphorylation in the presence of Ca2+ and calmodulin. Under these conditions, increase in protein phosphorylation was 47, 74 and 52% for 10 nM, 100 nM and 1 M L-T3, respectively. Chelation of Ca2+ using ethylene glycol-bis (2‑aminoethylether)-N, N, N’, N’-tetraacetic acid (EGTA) inhibited the effects of Ca2+/calmodulin on TH-stimulated protein phosphorylation levels. This study suggests that a high proportion of L-T3-stimulated protein phosphorylation involves Ca2+/calmodulin-dependent pathways in adult rat cerebrocortical synaptosomes.
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Protein phosphorylation is one of the most common post-translational modification processes that play an essential role in regulating protein functionality.The Helicoverpa armigera single nucleopolyhedrovirus (HearNPv) orf2-encoded nucleocapsid protein HA2 participates in orchestration of virus-induced actin polymerization through its WCA domain,in which phosphorylation status are supposed to be critical in respect to actin polymerization.In the present study,two putative phosphorylation sites (232Thr and 250Ser) and a highly conserved Serine (245Ser) on the WCA domain of HA2 were mutated,and their phenotypes were characterized by reintroducing the mutated HA2 into the HearNPV genome.Viral infectivity assays demonstrated that only the recombinant HearNPV bearing HA2 mutation at 245Ser can produce infectious virions,both 232Tbr and 250Ser mutations were lethal to the virus.However,actin polymerization assay demonstrated that all the three viruses bearing HA2 mutations were still capable of initiating actin polymerization in the host nucleus,which indicated the putative phosphorylation sites on HA2 may contribute to HearNPV replication through another unidentified pathway.
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A low-protein diet leads to functional and structural pancreatic islet alterations, including islet hypotrophy. Insulin-signaling pathways are involved in several adaptive responses by pancreatic islets. We determined the levels of some insulin-signaling proteins related to pancreatic islet function and growth in malnourished rats. Adult male Wistar rats (N = 20 per group) were fed a 17 percent protein (normal-protein diet; NP) or 6 percent protein (low-protein diet; LP), for 8 weeks. At the end of this period, blood glucose and serum insulin and albumin levels were measured. The morphometric parameters of the endocrine pancreas and the content of some proteins in islet lysates were determined. The β-cell mass was significantly reduced (≅65 percent) in normoglycemic but hypoinsulinemic LP rats compared to NP rats. Associated with these alterations, a significant 30 percent reduction in insulin receptor substrate-1 and a 70 percent increase in insulin receptor substrate-2 protein content were observed in LP islets compared to NP islets. The phosphorylated serine-threonine protein kinase (pAkt)/Akt protein ratio was similar in LP and NP islets. The phosphorylated forkhead-O1 (pFoxO1)/FoxO1 protein ratio was decreased by 43 percent in LP islets compared to NP islets (P < 0.05). Finally, the ratio of phosphorylated-extracellular signal-related kinase 1/2 (pErk1/2) to total Erk1/2 protein levels was decreased by 71 percent in LP islets compared to NP islets (P < 0.05). Therefore, the reduced β-cell mass observed in LP rats is associated with the reduction of phosphorylation in mitogenic-related signals, FoxO1 and Erk proteins. The cause/effect basis of this association remains to be determined.
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Animals , Male , Rats , Forkhead Transcription Factors/metabolism , Insulin-Secreting Cells/pathology , /metabolism , Nerve Tissue Proteins/metabolism , Protein-Energy Malnutrition , Diet, Protein-Restricted , Phosphorylation , Protein-Energy Malnutrition/metabolism , Protein-Energy Malnutrition/pathology , Rats, WistarABSTRACT
Long-Evans Cinnamon (LEC) mutant rat, which spontaneously develops a necrotizing hepatic injury at 4 ~5 months of age, reveals an excess hepatic copper accumulation and is a good model for studying the detail mechanism of cellular copper toxicity. We have observed the effects of copper toxicity on DNA synthesis upon growth stimulation by treating primary-cultured hepatocytes of LEC rat with epidermal growth factor (EGF) and insulin. DNA synthesis measured by [ 3 H]-thymidine incorporation and DNA synthesis S-phase cells in LEC rat significantly decreased when compared to those of normal F344 rat. Since DNA synthesis was impaired in LEC rat, we examined the detail mechanism by determining the histone content, which are involved in DNA stability, and the phosphorylation of nuclear protein. However, the histone contents and phosphorylated nuclear protein upon growth stimulation was intact in LEC rat. These results suggest that a cellular event other than protein phosphorylation required for the initiation of DNA synthesis upon growth stimulation is impaired by copper cytotoxicity in LEC rat.
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Animals , Rats , Cinnamomum zeylanicum , Copper , DNA , Epidermal Growth Factor , Hepatocytes , Histones , Insulin , Nuclear Proteins , Phosphorylation , Rats, Inbred F344ABSTRACT
PURPOSE: The purpose: of this study was to know the effect of inhibition of protein dephosphorylation on the synthesis of collagen and fibronectin (FN), alkaline phosphatase (ALP) activity, and the formation of bone nodule in MC3T3-E1 osteoblasts using orthovanadate (OVA) which is a potent protein tyrosine phosphatase (PTPases) inhibitor. MATERIALS AND METHODS: The synthesis of collagen, noncollagenous protein (NCP), and percent collagen in MC3T3-E1osteoblasts with or without OVA treatment according to concentration and time sequence was determined by incorporation of [3 H]-proline, synthesis of FN by [35 S] methionine incorproated immunoprecipitation after treatment with 100 M OVA for 24 hours, mRNA expression of collagen and FN by Northern blotting, activity of ALP by spectrophotometric method, and formation of bone nodule by staining method. RESULTS: OVA increased collagen and NCP synthesis concentration dependently, until 12 hours in short-time culture, and time dependently through the differentiation until 29 days, however, there was no significant effect on the percent collagen production. OVA increased percent collagen synthesis significantly at 6 hours, and decreased in a long time culture. Total FN synthesis and FN synthesis in cell layer were increased by OVA, however, FN synthesis in medium was not changed. OVA decreased collagen mRNA level dose-dependently and increased the steady-state level of FN mRNA. OVA inhibited activity of ALP in both short and long-time culture. OVA inhibited bone nodule formation in MC3T3-E1 osteoblasts. CONCLUSION: These results indicate that the inhibition of PTPase by OVA increased the synthesis of collagen, FN, and decreased ALP activity and it resulted in the inhibition of bone formation in MC3T3-E1 osteoblast cells.
Subject(s)
Alkaline Phosphatase , Blotting, Northern , Collagen , Fibronectins , Immunoprecipitation , Methionine , Osteoblasts , Osteogenesis , Ovum , Protein Tyrosine Phosphatases , RNA, Messenger , VanadatesABSTRACT
Aim To investigate the effects of ginsenoside(GS) on phosphorylation of tau protein,microtubule,cellular apoptosis and its related factors in cellular model of Alzheimer disease(AD) induced by the protein phosphatase 1 and 2A inhibitor okadaic acid(OA).Methods The human neuroblastoma cell line SK-N-SH cells were cultured with GS for 24 h,the culture medium was changed,and then incubated with OA 10 nmol?L-1 for 6 h.The changes of cell morphology were observed by inverted microscope.The laser confocal microscopy was used to observe the microtubule changes.Western blot was applied to determine the expression of phosphorylation of tau protein,and apoptosis-regulating factors Bcl-2,Bax and Caspase-3.The changes of apoptotic cells were observed by TUNEL method.Results The normal SK-N-SH cells spread well.OA-treated cells showed that the cell axons and the microtubules were broken and decreased under the inverted microscope and laser confocal microscope.Preincubation of GS demonstrated the significantly protective effects against the morphologic damage induced by OA.In OA-treated group,the phosphorylation of tau protein at Ser-199/202 and Ser-404 sites was higher than that in normal group,and the non-phosphorylation of tau protein at the same sites was lower;Incubation of GS at the dose of 50 mg?L-1 and 100 mg?L-1 with the cells decreased the phosphorylation of tau protein Ser-199/202 and Ser-404 sites.GS group at the dose of 50 mg?L-1 and 100 mg?L-1 decreased the expression of at non-phosphorylation of tau protein at the Ser202 site.The apoptotic cells were not found in normal group.The number of apoptotic cells were obviously increased.the expression of Bax and caspase-3 significantly enhanced,and Bcl-2 expression decreased in the OA-treated model group.GS significantly decreased the apoptotic cell number of nerve cells,inhibited the expression of Bax and caspase-3.Conclusion GS can protect the nerve cells from pathological change induced by OA.Maybe because it can inhibit the hyperphosphorylation of tau protein and protect the nerve cells from apoptosis,thus GS may have potential to treat Alzheimer disease.
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Objective:To investigate if chloride channel ClC-2 could be phosphorylated by mitogen activated protein kinase(MAPK) for further study of its regulation mechanism in proliferation and differentiation of cells.Methods:The coding sequence containing the cytosolic C-terminus of ClC-2 was amplified from pSPORT1/ClC-2 plasmid,including rabbit ClC-2 cDNA, by polymerase chain reaction(PCR),the fragment was cloned into pGEX-4T-1 plasmid for the construction of GST-tagged fusion protein expressing vector, pGEX-4T-1/ClC-2CT.After being identified by enzyme digestion and sequencing, the recombinant vector was transformed into a strain of E.coli BL21. The expression of GST-tagged fusion protein was induced with IPTG and purified with Gluthathion Sepharose 4B affinity chromatography. Then the phosphorylation of ClC-2 by MAPK was examined by using phosphorylation assays in vitro.Results:The construction of pGEX-4T-1/ClC-2CT recombinant vector was proved by enzyme digestion and sequencing. The purified fusion protein GST/ClC-2CT could be phosphorylated by MAPK, however the GST could not.Conclusion:Chloride channel ClC-2 can be phosphorylated by MAPK.