Ischemic stroke can cause blood-brain barrier(BBB)injury,which worsens brain damage induced by stroke.Abnormal expression of tight junction proteins in endothelial cells(ECs)can increase intracellular space and BBB le...Ischemic stroke can cause blood-brain barrier(BBB)injury,which worsens brain damage induced by stroke.Abnormal expression of tight junction proteins in endothelial cells(ECs)can increase intracellular space and BBB leakage.Selective inhibition of mitogen-activated protein kinase,the negative regulatory substrate of mitogen-activated protein kinase phosphatase(MKP)-1,improves tight junction protein function in ECs,and genetic deletion of MKP-1 aggravates ischemic brain injury.However,whether the latter affects BBB integrity,and the cell type-specific mechanism underlying this process,remain unclear.In this study,we established an adult male mouse model of ischemic stroke by occluding the middle cerebral artery for 60 minutes and overexpressed MKP-1 in ECs on the injured side via lentiviral transfection before stroke.We found that overexpression of MKP-1 in ECs reduced infarct volume,reduced the level of inflammatory factors interleukin-1β,interleukin-6,and chemokine C-C motif ligand-2,inhibited vascular injury,and promoted the recovery of sensorimotor and memory/cognitive function.Overexpression of MKP-1 in ECs also inhibited the activation of cerebral ischemia-induced extracellular signal-regulated kinase(ERK)1/2 and the downregulation of occludin expression.Finally,to investigate the mechanism by which MKP-1 exerted these functions in ECs,we established an ischemic stroke model in vitro by depriving the primary endothelial cell of oxygen and glucose,and pharmacologically inhibited the activity of MKP-1 and ERK1/2.Our findings suggest that MKP-1 inhibition aggravates oxygen and glucose deprivation-induced cell death,cell monolayer leakage,and downregulation of occludin expression,and that inhibiting ERK1/2 can reverse these effects.In addition,co-inhibition of MKP-1 and ERK1/2 exhibited similar effects to inhibition of ERK1/2.These findings suggest that overexpression of MKP-1 in ECs can prevent ischemia-induced occludin downregulation and cell death via deactivating ERK1/2,thereby protecting the integrity of BBB,alleviating brain injury,and improving post-stroke prognosis.展开更多
Studies have found that the phosphatase actin regulatory factor 1 expression can be related to stroke,but it remains unclear whether changes in phosphatase actin regulatory factor 1 expression also play a role in trau...Studies have found that the phosphatase actin regulatory factor 1 expression can be related to stroke,but it remains unclear whether changes in phosphatase actin regulatory factor 1 expression also play a role in traumatic brain injury.In this study we found that,in a mouse model of traumatic brain injury induced by controlled cortical impact,phosphatase actin regulatory factor 1 expression is increased in endothelial cells,neurons,astrocytes,and microglia.When we overexpressed phosphatase actin regulatory factor 1 by injection an adeno-associated virus vector into the contused area in the traumatic brain injury mice,the water content of the brain tissue increased.However,when phosphatase actin regulatory factor 1 was knocked down,the water content decreased.We also found that inhibiting phosphatase actin regulatory factor 1 expression regulated the nuclear factor kappa B signaling pathway,decreased blood-brain barrier permeability,reduced aquaporin 4 and intercellular adhesion molecule 1 expression,inhibited neuroinflammation,and neuronal apoptosis,thereby improving neurological function.The findings from this study indicate that phosphatase actin regulatory factor 1 may be a potential therapeutic target for traumatic brain injury.展开更多
This study is focused on the expression of an SH2 domain-truncated form of protein tyrosine phosphatase SHP-1(designated ΔSHP-1) and the preparation of its polyclonal antibodies. A cDNA fragment encoding ΔSHP-1 wa...This study is focused on the expression of an SH2 domain-truncated form of protein tyrosine phosphatase SHP-1(designated ΔSHP-1) and the preparation of its polyclonal antibodies. A cDNA fragment encoding ΔSHP-1 was amplified by PCR and then cloned into the pT7 expression vector. The recombinant pT7-ΔSHP-1 plasmid was used to transform Rosetta(DE3) E. coli cells. ΔSHP-1 was distributed in the exclusion body of E. coli cell extracts and was purified through a two-column chromatographic procedure. The purified enzyme exhibited an expected molecular weight on SDS-gels and HPLC gel filtration columns. It possesses robust tyrosine phosphatase activity and shows typical enzymatic characteristics of classic tyrosine phosphatases. To generate polyclonal anti-ΔSHP-1 antibodies, purified recombinant ΔSHP-1 was used to immunize a rabbit. The resultant anti-serum was subjected to purification on ΔSHP-1 antigen affinity chromatography. The purified polyclonal antibody displayed a high sensitivity and specificity toward ΔSHP-1. This study thus provides the essential materials for further investigating the biological function and pathological implication of SHP-1 and screening the inhibitors and activators of the enzyme for therapeutic drug development.展开更多
Objective: To investigate the relation between Shp-2 (a cytoplasmic tyrosine phosphotase) and matrix metalloproteinase-1 (MMP-1) in the migration of mouse embryo fibroblast cell. Methods: Shp-2 -/-embryo fibroblast wa...Objective: To investigate the relation between Shp-2 (a cytoplasmic tyrosine phosphotase) and matrix metalloproteinase-1 (MMP-1) in the migration of mouse embryo fibroblast cell. Methods: Shp-2 -/-embryo fibroblast was separated from Shp-2 knockout mouse on E10. 5, and Shp-2 cDNA was transfected into Shp-2 -/- cell. The cell migration was observed with the wound healing, the MMP-1 expression and secretion was analyzed by immunoblotting and immunoprecipitation. The activation of MMP-1 in the supernatant was detected with type I collagenase activity assay after the stimulation of IL-1α compared with E10. 5 mouse embryo fibroblast cell(Shp-2 +/+). Results: There was obvious migration in Shp-2 +/+ cells and Shp-2 -/-R cells, but not in Shp-2 -/- cells. The shape of Shp-2 -/- cell was epithelial-like. The expression and secretion was increased in Shp-2 +/+ cells and Shp-2 -/-R cells, and it had not changed in Shp-2 -/- cell. The activation of MMP-1 was lower in Shp-2 -/- cells compared to the other cells. Conclusion: IL-1 induces the expression and secretion of MMP-1α at the physical dose, and the cell migration is involved in MMP-1 by way of Shp-2 signal transduction.展开更多
Cellular biological activities are tightly controlled by intracellular signaling processes initiated by extracellular signals. Protein tyrosine phosphatases, which remove phosphate groups from phosphorylated signaling...Cellular biological activities are tightly controlled by intracellular signaling processes initiated by extracellular signals. Protein tyrosine phosphatases, which remove phosphate groups from phosphorylated signaling molecules, play equally important tyrosine roles as protein tyrosine kinases in signal transduction. SHP-2, a cytoplajsmic SH2 domain containing protein tyrosine phosphatase, is involved in the signaling pathways of a variety of growth factors and cytokines. Recent studies have clearly demonstrated that this phosphatase plays an important role in transducing signal relay from the cell surface to the nucleus, and is a critical intracellular regulator in mediating cell proliferation and differentiation.展开更多
AIM:To investigate whether silencing Fas-associated phosphatase 1(FAP-1)expression enhances the efficiency of chemotherapy for colon carcinoma with oxaliplatin.METHODS:Expression of FAP-1 in mRNA and protein was detec...AIM:To investigate whether silencing Fas-associated phosphatase 1(FAP-1)expression enhances the efficiency of chemotherapy for colon carcinoma with oxaliplatin.METHODS:Expression of FAP-1 in mRNA and protein was detected by reverse transcription polymerase chain reaction(RT-PCR)and flow cytometry.Small interfering RNA(siRNA)was designed according to the FAP-1 mRNA sequence.Cell proliferation was evaluated by methyl thiazolyl tetrazolium(MTT)assay.Anenxin V-and propidine iodine(PI)were assayed by flow cytometry for the detection of apoptosis. RESULTS:The expression of FAP-1 was increased in SW480 cells after chemotherapy with oxaliplatin. Transfection of FAP-1 siRNA into SW480 cells silenced the expression of FAP-1 and consequently abolished the inhibitory function of Fas/FasL-mediated apoptosis pathway,thus increasing the efficacy of chemotherapy for colon carcinoma with oxaliplatin. CONCLUSION:RNA interference combined with conventional chemotherapy is more effective against colon cancer.展开更多
Cementum is critical for anchoring the insertion of periodontal ligament fibers to the tooth root. Several aspects of cementogenesis remain unclear, including differences between acellular cementum and cellular cement...Cementum is critical for anchoring the insertion of periodontal ligament fibers to the tooth root. Several aspects of cementogenesis remain unclear, including differences between acellular cementum and cellular cementum, and between cementum and bone. Biomineralization is regulated by the ratio of inorganic phosphate (Pi) to mineral inhibitor pyrophosphate (PPi), where local Pi and PPi concentrations are controlled by phosphatases including tissue-nonspecific alkaline phosphatase (TNAP) and ectonucleotide pyrophosphatase/phosphodiesterase 1 (NPP1). The focus of this study was to define the roles of these phosphatases in cementogenesis. TNAP was associated with earliest cementoblasts near forming acellular and cellular cementum. With loss of TNAP in the Alpl null mouse, acellular cementum was inhibited, while cellular cementum production increased, albeit as hypomineralized cementoid. In contrast, NPP1 was detected in cementoblasts after acellular cementum formation, and at low levels around cellular cementum. Loss of NPP1 in the Enppl null mouse increased acellular cementum, with little effect on cellular cementum. Developmental patterns were recapitulated in a mouse model for acellular cementum regeneration, with early TNAP expression and later NPP1 expression. In vitro, cementoblasts expressed Alpl gene/protein early, whereas Enppl gene/protein expression was significantly induced only under mineralization conditions. These patterns were confirmed in human teeth, including widespread TNAP, and NPP1 restricted to cementoblasts lining acellular cementum. These studies suggest that early TNAP expression creates a low PPi environment promoting acellular cementum initiation, while later NPP1 expression increases PPi, restricting acellular cementum apposition. Alterations in PPi have little effect on cellular cementum formation, though matrix mineralization is affected.展开更多
The mitogen-activated protein kinase(MAPK) signaling pathway plays an important role in the regulation of cell growth, proliferation, differentiation, transformation and death. Mitogen-activated protein kinase phosp...The mitogen-activated protein kinase(MAPK) signaling pathway plays an important role in the regulation of cell growth, proliferation, differentiation, transformation and death. Mitogen-activated protein kinase phosphatase 1(MKP1) has an inhibitory effect on the p38 MAPK and JNK pathways, but it is unknown whether it plays a role in Aβ-induced oxidative stress and neuronal inflammation. In this study, PC12 cells were infected with MKP1 sh RNA, MKP1 lentivirus or control lentivirus for 12 hours, and then treated with 0.1, 1, 10 or 100 μM amyloid beta 42(Aβ42). The cell survival rate was measured using the cell counting kit-8 assay. MKP1, tumor necrosis factor-alpha(TNF-α) and interleukin-1β(IL-1β) m RNA expression levels were analyzed using quantitative real time-polymerase chain reaction. MKP1 and phospho-c-Jun N-terminal kinase(JNK) expression levels were assessed using western blot assay. Reactive oxygen species(ROS) levels were detected using 2′,7′-dichlorofluorescein diacetate. Mitochondrial membrane potential was measured using flow cytometry. Superoxide dismutase activity and malondialdehyde levels were evaluated using the colorimetric method. Lactate dehydrogenase activity was measured using a microplate reader. Caspase-3 expression levels were assessed by enzyme-linked immunosorbent assay. Apoptosis was evaluated using the terminal deoxynucleotidyl transferase d UTP nick end labeling method. MKP1 overexpression inhibited Aβ-induced JNK phosphorylation and the increase in ROS levels. It also suppressed the Aβ-induced increase in TNF-α and IL-1β levels as well as apoptosis in PC12 cells. In contrast, MKP1 knockdown by RNA interference aggravated Aβ-induced oxidative stress, inflammation and cell damage in PC12 cells. Furthermore, the JNK-specific inhibitor SP600125 abolished this effect of MKP1 knockdown on Aβ-induced neurotoxicity. Collectively, these results show that MKP1 mitigates Aβ-induced apoptosis, oxidative stress and neuroinflammation by inhibiting the JNK signaling pathway, thereby playing a neuroprotective role.展开更多
The expression of phosphatase and tensin homolog (PTEN ), a tumor suppressor gene, is frequently downregulated in gastric carcinomas due to mutation, loss of heterozygosity, and promoter hypermethylation. However, it ...The expression of phosphatase and tensin homolog (PTEN ), a tumor suppressor gene, is frequently downregulated in gastric carcinomas due to mutation, loss of heterozygosity, and promoter hypermethylation. However, it is unknown if additional mechanisms may account for the down-regulation of PTEN expression. While neuronal precursor cell-expressed developmentally down-regulated 4-1 (NEDD4-1) is believed to be a potential dual regulator of PTEN, there are conflicting reports regarding their interaction. To gain further insight into the role of NEDD4-1 and its association with PTEN in gastric carcinoma development, we measured the protein expression of NEDD4-1 and PTEN in gastric mucosae with various pathological lesions and found that NEDD4-1 increased from normal gastric mucosa to intestinal metaplasia and decreased from dysplasia to gastric carcinoma. These changes did not correlate with PTEN expression changes during gastric carcinogenesis. Moreover, we found similar results in protein levels in the primary tumors and adjacent non-tumorous tissues. These results differ from a previous report showing that expression of NEDD4-1 is up-regulated in gastric carcinomas, and show a more complex pattern of NEDD4-1 gene expression during gastric carcinogenesis.展开更多
AIMTo evaluate whether protein tyrosine phosphatase 1B (PTP1B) contributed to initiate human retinal pigment epithelium cells (A)-19 migration and investigate the signaling pathways involved in this process.METHODSARP...AIMTo evaluate whether protein tyrosine phosphatase 1B (PTP1B) contributed to initiate human retinal pigment epithelium cells (A)-19 migration and investigate the signaling pathways involved in this process.METHODSARPE-19 cells were cultured and treated with the siRNA-PTP1B. Expression of PTP1B was confirmed by quantitative reverse transcriptase-polymerase chain reaction (qRT-PCR). AG1478 [a selective inhibitor of epidermal growth factor receptor (EGFR)] and PD98059 (a specific inhibitor of the activation of mitogen-activated protein kinase) were used to help to determine the PTP1B signaling mechanism. Western blot analysis verified expression of EGFR and extracellular signal-regulated kinase (ERK) in ARPE-19 cells. The effect of siRNA-PTP1B on cell differentiation was confirmed by immunostaining for α-smooth muscle actin (α-SMA) and qRT-PCR. Cell migration ability was analyzed by transwell chamber assay.RESULTSThe mRNA levels of PTP1B were reduced by siRNA-PTP1B as determined by qRT-PCR assay. SiRNA-PTP1B activated EGFR and ERK phosphorylation. α-SMA staining and qRT-PCR assay demonstrated that siRNA-PTP1B induced retinal pigment epithelium (RPE) cells to differentiate toward better contractility and motility. Transwell chamber assay proved that PTP1B inhibition improved migration activity of RPE cells. Treatment with AG1478 and PD98059 abolished siRNA-PTP1B-induced activation of EGFR and ERK, α-SMA expression and cell migration.CONCLUSIONPTP1B inhibition promoted myofibroblast differentiation and migration of ARPE-19 cells, and EGFR/ERK signaling pathway played important role in migration process.展开更多
3-bromo-4,5-bis(2,3-dibromo-4,5-dihydroxybenzyl)-l,2-benzenediol (1) is a natural bromophenol isolated from the red algae Rhodomela confervoides that exhibits significant inhibition against protein tyrosine phosph...3-bromo-4,5-bis(2,3-dibromo-4,5-dihydroxybenzyl)-l,2-benzenediol (1) is a natural bromophenol isolated from the red algae Rhodomela confervoides that exhibits significant inhibition against protein tyrosine phosphatase 1B (PTP1B). Based on its activity, we synthesized two new synthetic bromophenols and their methoxy derivatives from vanillin using the structure of natural bromophenol 1 as a scaffold. The structures of these bromophenols were elucidated from H NMR, 13C NMR, and high resolution electron ionization mass spectrometry as 2,3-dibromo-1-(2'-bromo-6'-(3",4"-dimethoxybenzyl)- 3 ',4 '-dimethoxybenzyl)-4,5 -dimethoxybenzene (2), 2,3-dibromo- 1 -(2 '-bromo-6'-(2 "-bromo-4",5 "-dimethoxy- benzyl)-3',4'-dimethoxybenzyl)-4,5-dimethoxybenzene (3), 3,4-dibromo-5-(2'-bromo-6'-(2"-bromo-4",5"- dihydroxybenzyl)-3',4'-dihydroxybenzyl)pyrocatechol (4) and 3,4-dibromo-5-(2'-bromo-6'-(3",4"- dihydroxybenzyl)-3',4'-dihydroxybenzyl)pyrocatechol (5). PTP1B inhibition activities of these compounds were evaluated using a colorimetric assay, and compounds 3 and 4 demonstrated interesting activity against PTP1B.展开更多
Oleanolic acid derivatives act as newer protein tyrosine phosphatase 1B (PTP-1B) inhibitors for type 2 diabetes mellitus (T2DM). In order to understand the structural requirement of PTP-1B inhibitors, 52 oleanolic...Oleanolic acid derivatives act as newer protein tyrosine phosphatase 1B (PTP-1B) inhibitors for type 2 diabetes mellitus (T2DM). In order to understand the structural requirement of PTP-1B inhibitors, 52 oleanolic acid derivatives were divided into a training set (34 compounds) and a test set (18 compounds). The highly reliable and predictive 3D-QSAR models were constructed by CoMFA, CoMSIA and topomer CoMFA methods, respectively. The results showed that the cross validated coefficient (q2) and non-cross-validated coefficient (R2) were 0.554 and 0.999 in the CoMFA model, 0.675 and 0.971 in the CoMSIA model, and 0.628 and 0.939 in the topomer CoMFA model, which suggests that three models are robust and have good exterior predictive capabilities. Furthermore, ten novel inhibitors with much higher inhibitory potency were designed. Our design strategy was that (i) the electronegative substituents (Cl, -CH2OH, OH and -CH2Cl) were introduced into the double bond of ring C, (ii) the hydrogen bond acceptor groups (C≡N and N atom), electronegative groups (C≡N, N atom, -COOH and -COOCH3) and bulky substituents (C6H5N) were connected to the C-3 position, which would result in generating potent and selective PTP-1B inhibitors. We expect that the results in this paper have the potential to facilitate the process of design and to develop new potent PTP-1B inhibitors.展开更多
基金supported by Research Start-up Funding of Shenzhen Traditional Chinese Medicine Hospital,No.2021-07(to FB)Sanming Project of Medicine in Shenzhen,No.SZZYSM 202111011(to XDQ and FB)+1 种基金Key Discipline Established by Zhejiang Province,Jiaxing City Jointly-Pain Medicine,No.2019-ss-ttyx(to LSX)Jiaxing Key Laboratory of Neurology and Pain Medicine,No.[2014]81(to LSX)。
文摘Ischemic stroke can cause blood-brain barrier(BBB)injury,which worsens brain damage induced by stroke.Abnormal expression of tight junction proteins in endothelial cells(ECs)can increase intracellular space and BBB leakage.Selective inhibition of mitogen-activated protein kinase,the negative regulatory substrate of mitogen-activated protein kinase phosphatase(MKP)-1,improves tight junction protein function in ECs,and genetic deletion of MKP-1 aggravates ischemic brain injury.However,whether the latter affects BBB integrity,and the cell type-specific mechanism underlying this process,remain unclear.In this study,we established an adult male mouse model of ischemic stroke by occluding the middle cerebral artery for 60 minutes and overexpressed MKP-1 in ECs on the injured side via lentiviral transfection before stroke.We found that overexpression of MKP-1 in ECs reduced infarct volume,reduced the level of inflammatory factors interleukin-1β,interleukin-6,and chemokine C-C motif ligand-2,inhibited vascular injury,and promoted the recovery of sensorimotor and memory/cognitive function.Overexpression of MKP-1 in ECs also inhibited the activation of cerebral ischemia-induced extracellular signal-regulated kinase(ERK)1/2 and the downregulation of occludin expression.Finally,to investigate the mechanism by which MKP-1 exerted these functions in ECs,we established an ischemic stroke model in vitro by depriving the primary endothelial cell of oxygen and glucose,and pharmacologically inhibited the activity of MKP-1 and ERK1/2.Our findings suggest that MKP-1 inhibition aggravates oxygen and glucose deprivation-induced cell death,cell monolayer leakage,and downregulation of occludin expression,and that inhibiting ERK1/2 can reverse these effects.In addition,co-inhibition of MKP-1 and ERK1/2 exhibited similar effects to inhibition of ERK1/2.These findings suggest that overexpression of MKP-1 in ECs can prevent ischemia-induced occludin downregulation and cell death via deactivating ERK1/2,thereby protecting the integrity of BBB,alleviating brain injury,and improving post-stroke prognosis.
基金supported by the National Natural Science Foundation of China,Nos.81501048(to JD),81801236(to ZMX),81974189(to HLT)Shanghai 6th People’s Hospital Research Fund,No.ynlc201808(to JD).
文摘Studies have found that the phosphatase actin regulatory factor 1 expression can be related to stroke,but it remains unclear whether changes in phosphatase actin regulatory factor 1 expression also play a role in traumatic brain injury.In this study we found that,in a mouse model of traumatic brain injury induced by controlled cortical impact,phosphatase actin regulatory factor 1 expression is increased in endothelial cells,neurons,astrocytes,and microglia.When we overexpressed phosphatase actin regulatory factor 1 by injection an adeno-associated virus vector into the contused area in the traumatic brain injury mice,the water content of the brain tissue increased.However,when phosphatase actin regulatory factor 1 was knocked down,the water content decreased.We also found that inhibiting phosphatase actin regulatory factor 1 expression regulated the nuclear factor kappa B signaling pathway,decreased blood-brain barrier permeability,reduced aquaporin 4 and intercellular adhesion molecule 1 expression,inhibited neuroinflammation,and neuronal apoptosis,thereby improving neurological function.The findings from this study indicate that phosphatase actin regulatory factor 1 may be a potential therapeutic target for traumatic brain injury.
基金the Fund of Science & Technology Bureau of Jilin Province, China(Nos.20060563, 200705394 and 20080434).
文摘This study is focused on the expression of an SH2 domain-truncated form of protein tyrosine phosphatase SHP-1(designated ΔSHP-1) and the preparation of its polyclonal antibodies. A cDNA fragment encoding ΔSHP-1 was amplified by PCR and then cloned into the pT7 expression vector. The recombinant pT7-ΔSHP-1 plasmid was used to transform Rosetta(DE3) E. coli cells. ΔSHP-1 was distributed in the exclusion body of E. coli cell extracts and was purified through a two-column chromatographic procedure. The purified enzyme exhibited an expected molecular weight on SDS-gels and HPLC gel filtration columns. It possesses robust tyrosine phosphatase activity and shows typical enzymatic characteristics of classic tyrosine phosphatases. To generate polyclonal anti-ΔSHP-1 antibodies, purified recombinant ΔSHP-1 was used to immunize a rabbit. The resultant anti-serum was subjected to purification on ΔSHP-1 antigen affinity chromatography. The purified polyclonal antibody displayed a high sensitivity and specificity toward ΔSHP-1. This study thus provides the essential materials for further investigating the biological function and pathological implication of SHP-1 and screening the inhibitors and activators of the enzyme for therapeutic drug development.
文摘Objective: To investigate the relation between Shp-2 (a cytoplasmic tyrosine phosphotase) and matrix metalloproteinase-1 (MMP-1) in the migration of mouse embryo fibroblast cell. Methods: Shp-2 -/-embryo fibroblast was separated from Shp-2 knockout mouse on E10. 5, and Shp-2 cDNA was transfected into Shp-2 -/- cell. The cell migration was observed with the wound healing, the MMP-1 expression and secretion was analyzed by immunoblotting and immunoprecipitation. The activation of MMP-1 in the supernatant was detected with type I collagenase activity assay after the stimulation of IL-1α compared with E10. 5 mouse embryo fibroblast cell(Shp-2 +/+). Results: There was obvious migration in Shp-2 +/+ cells and Shp-2 -/-R cells, but not in Shp-2 -/- cells. The shape of Shp-2 -/- cell was epithelial-like. The expression and secretion was increased in Shp-2 +/+ cells and Shp-2 -/-R cells, and it had not changed in Shp-2 -/- cell. The activation of MMP-1 was lower in Shp-2 -/- cells compared to the other cells. Conclusion: IL-1 induces the expression and secretion of MMP-1α at the physical dose, and the cell migration is involved in MMP-1 by way of Shp-2 signal transduction.
文摘Cellular biological activities are tightly controlled by intracellular signaling processes initiated by extracellular signals. Protein tyrosine phosphatases, which remove phosphate groups from phosphorylated signaling molecules, play equally important tyrosine roles as protein tyrosine kinases in signal transduction. SHP-2, a cytoplajsmic SH2 domain containing protein tyrosine phosphatase, is involved in the signaling pathways of a variety of growth factors and cytokines. Recent studies have clearly demonstrated that this phosphatase plays an important role in transducing signal relay from the cell surface to the nucleus, and is a critical intracellular regulator in mediating cell proliferation and differentiation.
基金Supported by Research grants from the Science and Technology Foundation of Guangdong Province,No.2006B36002010,2008B030301092,2009B030801005the Foundation of Health Department of Guangdong Province,No.A2005226+2 种基金the foundation of Guangzhou Science and Technology Bureau,No. 2009Y-C011-1the Natural Science Foundation of Guangdong Province,No.7001592the National Natural Science Foundation of China,No.30973505
文摘AIM:To investigate whether silencing Fas-associated phosphatase 1(FAP-1)expression enhances the efficiency of chemotherapy for colon carcinoma with oxaliplatin.METHODS:Expression of FAP-1 in mRNA and protein was detected by reverse transcription polymerase chain reaction(RT-PCR)and flow cytometry.Small interfering RNA(siRNA)was designed according to the FAP-1 mRNA sequence.Cell proliferation was evaluated by methyl thiazolyl tetrazolium(MTT)assay.Anenxin V-and propidine iodine(PI)were assayed by flow cytometry for the detection of apoptosis. RESULTS:The expression of FAP-1 was increased in SW480 cells after chemotherapy with oxaliplatin. Transfection of FAP-1 siRNA into SW480 cells silenced the expression of FAP-1 and consequently abolished the inhibitory function of Fas/FasL-mediated apoptosis pathway,thus increasing the efficacy of chemotherapy for colon carcinoma with oxaliplatin. CONCLUSION:RNA interference combined with conventional chemotherapy is more effective against colon cancer.
基金supported by the Intramural Research Program of the National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS) of the National Institutes of Health (NIH) and extramural NIH funding(JLM-DE12889 and AR53102)
文摘Cementum is critical for anchoring the insertion of periodontal ligament fibers to the tooth root. Several aspects of cementogenesis remain unclear, including differences between acellular cementum and cellular cementum, and between cementum and bone. Biomineralization is regulated by the ratio of inorganic phosphate (Pi) to mineral inhibitor pyrophosphate (PPi), where local Pi and PPi concentrations are controlled by phosphatases including tissue-nonspecific alkaline phosphatase (TNAP) and ectonucleotide pyrophosphatase/phosphodiesterase 1 (NPP1). The focus of this study was to define the roles of these phosphatases in cementogenesis. TNAP was associated with earliest cementoblasts near forming acellular and cellular cementum. With loss of TNAP in the Alpl null mouse, acellular cementum was inhibited, while cellular cementum production increased, albeit as hypomineralized cementoid. In contrast, NPP1 was detected in cementoblasts after acellular cementum formation, and at low levels around cellular cementum. Loss of NPP1 in the Enppl null mouse increased acellular cementum, with little effect on cellular cementum. Developmental patterns were recapitulated in a mouse model for acellular cementum regeneration, with early TNAP expression and later NPP1 expression. In vitro, cementoblasts expressed Alpl gene/protein early, whereas Enppl gene/protein expression was significantly induced only under mineralization conditions. These patterns were confirmed in human teeth, including widespread TNAP, and NPP1 restricted to cementoblasts lining acellular cementum. These studies suggest that early TNAP expression creates a low PPi environment promoting acellular cementum initiation, while later NPP1 expression increases PPi, restricting acellular cementum apposition. Alterations in PPi have little effect on cellular cementum formation, though matrix mineralization is affected.
文摘The mitogen-activated protein kinase(MAPK) signaling pathway plays an important role in the regulation of cell growth, proliferation, differentiation, transformation and death. Mitogen-activated protein kinase phosphatase 1(MKP1) has an inhibitory effect on the p38 MAPK and JNK pathways, but it is unknown whether it plays a role in Aβ-induced oxidative stress and neuronal inflammation. In this study, PC12 cells were infected with MKP1 sh RNA, MKP1 lentivirus or control lentivirus for 12 hours, and then treated with 0.1, 1, 10 or 100 μM amyloid beta 42(Aβ42). The cell survival rate was measured using the cell counting kit-8 assay. MKP1, tumor necrosis factor-alpha(TNF-α) and interleukin-1β(IL-1β) m RNA expression levels were analyzed using quantitative real time-polymerase chain reaction. MKP1 and phospho-c-Jun N-terminal kinase(JNK) expression levels were assessed using western blot assay. Reactive oxygen species(ROS) levels were detected using 2′,7′-dichlorofluorescein diacetate. Mitochondrial membrane potential was measured using flow cytometry. Superoxide dismutase activity and malondialdehyde levels were evaluated using the colorimetric method. Lactate dehydrogenase activity was measured using a microplate reader. Caspase-3 expression levels were assessed by enzyme-linked immunosorbent assay. Apoptosis was evaluated using the terminal deoxynucleotidyl transferase d UTP nick end labeling method. MKP1 overexpression inhibited Aβ-induced JNK phosphorylation and the increase in ROS levels. It also suppressed the Aβ-induced increase in TNF-α and IL-1β levels as well as apoptosis in PC12 cells. In contrast, MKP1 knockdown by RNA interference aggravated Aβ-induced oxidative stress, inflammation and cell damage in PC12 cells. Furthermore, the JNK-specific inhibitor SP600125 abolished this effect of MKP1 knockdown on Aβ-induced neurotoxicity. Collectively, these results show that MKP1 mitigates Aβ-induced apoptosis, oxidative stress and neuroinflammation by inhibiting the JNK signaling pathway, thereby playing a neuroprotective role.
基金Supported by Grants from the National Natural Science Foundation of China, No. 81060038the Graduate Innovative Fund of Jiangxi Province, No. YC10A020
文摘The expression of phosphatase and tensin homolog (PTEN ), a tumor suppressor gene, is frequently downregulated in gastric carcinomas due to mutation, loss of heterozygosity, and promoter hypermethylation. However, it is unknown if additional mechanisms may account for the down-regulation of PTEN expression. While neuronal precursor cell-expressed developmentally down-regulated 4-1 (NEDD4-1) is believed to be a potential dual regulator of PTEN, there are conflicting reports regarding their interaction. To gain further insight into the role of NEDD4-1 and its association with PTEN in gastric carcinoma development, we measured the protein expression of NEDD4-1 and PTEN in gastric mucosae with various pathological lesions and found that NEDD4-1 increased from normal gastric mucosa to intestinal metaplasia and decreased from dysplasia to gastric carcinoma. These changes did not correlate with PTEN expression changes during gastric carcinogenesis. Moreover, we found similar results in protein levels in the primary tumors and adjacent non-tumorous tissues. These results differ from a previous report showing that expression of NEDD4-1 is up-regulated in gastric carcinomas, and show a more complex pattern of NEDD4-1 gene expression during gastric carcinogenesis.
基金Supported by Shandong Provincial Natural Science Foundation,China(No.ZR2012HQ004)the Research Fund for Fundamental Research Project of Qingdao(No.13-1-4-180-jch)+1 种基金the Scientific Research Fund of Huangdao District of Qingdao City(No.2014-1-74)the Young People Scientific Research Fund of Affiliated Hospital,Qingdao University(No.QDFY134)
文摘AIMTo evaluate whether protein tyrosine phosphatase 1B (PTP1B) contributed to initiate human retinal pigment epithelium cells (A)-19 migration and investigate the signaling pathways involved in this process.METHODSARPE-19 cells were cultured and treated with the siRNA-PTP1B. Expression of PTP1B was confirmed by quantitative reverse transcriptase-polymerase chain reaction (qRT-PCR). AG1478 [a selective inhibitor of epidermal growth factor receptor (EGFR)] and PD98059 (a specific inhibitor of the activation of mitogen-activated protein kinase) were used to help to determine the PTP1B signaling mechanism. Western blot analysis verified expression of EGFR and extracellular signal-regulated kinase (ERK) in ARPE-19 cells. The effect of siRNA-PTP1B on cell differentiation was confirmed by immunostaining for α-smooth muscle actin (α-SMA) and qRT-PCR. Cell migration ability was analyzed by transwell chamber assay.RESULTSThe mRNA levels of PTP1B were reduced by siRNA-PTP1B as determined by qRT-PCR assay. SiRNA-PTP1B activated EGFR and ERK phosphorylation. α-SMA staining and qRT-PCR assay demonstrated that siRNA-PTP1B induced retinal pigment epithelium (RPE) cells to differentiate toward better contractility and motility. Transwell chamber assay proved that PTP1B inhibition improved migration activity of RPE cells. Treatment with AG1478 and PD98059 abolished siRNA-PTP1B-induced activation of EGFR and ERK, α-SMA expression and cell migration.CONCLUSIONPTP1B inhibition promoted myofibroblast differentiation and migration of ARPE-19 cells, and EGFR/ERK signaling pathway played important role in migration process.
基金Supported by the National Major Research Program of China"The Creation for Significant Innovative Drugs"(No.2009ZX09103-148)the Natural Science Foundation of Shandong(No.BS2009YY011)+1 种基金the Natural Science Foundation of Qingdao(No.10-3-4-8-2-JCH)the Program of Qingdao Shinan District(No.2009-HY-2-14)
文摘3-bromo-4,5-bis(2,3-dibromo-4,5-dihydroxybenzyl)-l,2-benzenediol (1) is a natural bromophenol isolated from the red algae Rhodomela confervoides that exhibits significant inhibition against protein tyrosine phosphatase 1B (PTP1B). Based on its activity, we synthesized two new synthetic bromophenols and their methoxy derivatives from vanillin using the structure of natural bromophenol 1 as a scaffold. The structures of these bromophenols were elucidated from H NMR, 13C NMR, and high resolution electron ionization mass spectrometry as 2,3-dibromo-1-(2'-bromo-6'-(3",4"-dimethoxybenzyl)- 3 ',4 '-dimethoxybenzyl)-4,5 -dimethoxybenzene (2), 2,3-dibromo- 1 -(2 '-bromo-6'-(2 "-bromo-4",5 "-dimethoxy- benzyl)-3',4'-dimethoxybenzyl)-4,5-dimethoxybenzene (3), 3,4-dibromo-5-(2'-bromo-6'-(2"-bromo-4",5"- dihydroxybenzyl)-3',4'-dihydroxybenzyl)pyrocatechol (4) and 3,4-dibromo-5-(2'-bromo-6'-(3",4"- dihydroxybenzyl)-3',4'-dihydroxybenzyl)pyrocatechol (5). PTP1B inhibition activities of these compounds were evaluated using a colorimetric assay, and compounds 3 and 4 demonstrated interesting activity against PTP1B.
基金Supported by the Natural Science Foundation of Guangxi Province(Nos.2013GXNSFAA019019 and 2013GXNSFAA019041)
文摘Oleanolic acid derivatives act as newer protein tyrosine phosphatase 1B (PTP-1B) inhibitors for type 2 diabetes mellitus (T2DM). In order to understand the structural requirement of PTP-1B inhibitors, 52 oleanolic acid derivatives were divided into a training set (34 compounds) and a test set (18 compounds). The highly reliable and predictive 3D-QSAR models were constructed by CoMFA, CoMSIA and topomer CoMFA methods, respectively. The results showed that the cross validated coefficient (q2) and non-cross-validated coefficient (R2) were 0.554 and 0.999 in the CoMFA model, 0.675 and 0.971 in the CoMSIA model, and 0.628 and 0.939 in the topomer CoMFA model, which suggests that three models are robust and have good exterior predictive capabilities. Furthermore, ten novel inhibitors with much higher inhibitory potency were designed. Our design strategy was that (i) the electronegative substituents (Cl, -CH2OH, OH and -CH2Cl) were introduced into the double bond of ring C, (ii) the hydrogen bond acceptor groups (C≡N and N atom), electronegative groups (C≡N, N atom, -COOH and -COOCH3) and bulky substituents (C6H5N) were connected to the C-3 position, which would result in generating potent and selective PTP-1B inhibitors. We expect that the results in this paper have the potential to facilitate the process of design and to develop new potent PTP-1B inhibitors.