Background The cellular repressor of ElA-stimulated genes(CREG)is a secreted glycoprotein that inhibits cell proliferation and/or enhances differentiation.CREG is widely expressed in adult tissues such as the brain,he...Background The cellular repressor of ElA-stimulated genes(CREG)is a secreted glycoprotein that inhibits cell proliferation and/or enhances differentiation.CREG is widely expressed in adult tissues such as the brain,heart,lungs,liver,intestines and kidneys in mice.We investigated the level of CREG expression during mouse embryogenesis and its distribution at 18.5 days post coitus(dpc).Methods Immunohistochemical staining with diaminobenzidine,western blotting and reverse transcription-polymerase chain reaction were used.Results CREG expression was rst detected in mouse embryos at 4.5 dpc.It was expressed at almost all stages up to 18.5 dpc.The level of CREG was found to increase gradually and was highest at 18.5 dpc.Western blotting showed that the CREG protein was expressed at higher levels in the brain,heart,intestines and kidneys than in the lungs and liver at 18.5 dpc.In 9.5 dpc embryos,CREG was expressed only in the endothelial cells of blood vessels,after the vascular lumen had formed.With advanced differentiation,vascular smooth muscle cells developed in the embryonic vascular structures;the expression of smooth muscle a-actin protein and CREG were positive and increased gradually in 10.5 dpc embryonic vessels.CREG expression in the embryonic blood vessels peaked at 15.5 dpc and was reduced slightly at 18.5 dpc.Conclusions These results indicate that CREG is expressed during mouse embryogenesis and might participate in the differentiation of these organs during embryogenesis.展开更多
目的:建立心肌特异性Creg基因敲除小鼠并初步分析其表型。方法:利用订购的Creg两端插入lox P位点(Cregflox/flox)的小鼠与肌型肌酸激酶特异性启动子驱动的Cre重组酶转基因(Ckmm-cre)小鼠交配,获得Cregflox/+/Ckmm-cre小鼠。再利用Cregfl...目的:建立心肌特异性Creg基因敲除小鼠并初步分析其表型。方法:利用订购的Creg两端插入lox P位点(Cregflox/flox)的小鼠与肌型肌酸激酶特异性启动子驱动的Cre重组酶转基因(Ckmm-cre)小鼠交配,获得Cregflox/+/Ckmm-cre小鼠。再利用Cregflox/+/Ckmm-cre小鼠互相交配,获得基因型为Cregflox/flox/Ckmm-cre的心肌特异性Creg基因条件敲除(Creg conditional knockout,Creg c KO)小鼠。用PCR法进行基因型鉴定。用定量PCR及Western Blot检测心肌组织中Creg表达水平。HE染色观察敲除小鼠与同窝野生型对照小鼠心脏大小及形态。检测两组小鼠心电图。用小动物超声评价两组小鼠左心室收缩功能。结果:1经基因型鉴定,成功获得Creg c KO小鼠。2与野生型对照相比,Creg c KO小鼠心脏中CREG在转录及翻译水平表达降低90%以上。3与野生型对照相比,Cre c KO小鼠的心脏大小、形态、心电图及左心室射血分数均无显著差别。结论:成功建立心肌特异性CREG基因条件敲除小鼠,为进一步研究Creg在心脏疾病中的作用和机制提供了有力的工具。展开更多
Background The present study aimed to investigate the detailed mode and specific sites for their binding as well as the functional relevance of this binding in the phenotypic proliferation of vascular smooth muscle ce...Background The present study aimed to investigate the detailed mode and specific sites for their binding as well as the functional relevance of this binding in the phenotypic proliferation of vascular smooth muscle cells(SMCs). Methods CREG knocked-down SMCs were employed to evaluate the biological activity of wtCREG and mCREG.Expressions of SMC differentiation markers SM myosin heavy chain(SM-MHC),SM-actin,heavy caldesmon and myocardin were determined by Western blotting using specific antibodies. Cellular growth of SMCs was assessed by bromide dewuridine (BrdU) incorporation and cell cycle analysis on fluorescence-activated cell sorting(FACS).A solid-phase binding assay was used to study the binding of CREG to extracellular domains of M6P/IGF2R.The cellular co-localization of the two recombinant CREGs with M6P/IGF2R was detected on SMC surface by immunoprecipitation and immunofluorescence analysis.Results The molecular weight of wtCREG was around 30 kD while that of the mCREG was～25 kD.Treatment of wtCREG with PNGase F reduced its molecular weight from～30 kD to～25 kD,whereas PNGase F treatment had no effect on the molecular weight of mCREG.Both wtCREG and mCREG proteins enhanced SMC differentiation,inhibited BrdU incorporation,and arrested cell cycle progression when added to the culture medium.In CREG knocked-down SMCs,the amount of CREG detected by immunoblotting in M6P/IGF2R immunoprecipitates was significantly reduced when compared to normal cells.Both recombinant CREGs co-immunoprecipitated with M6P/IGF2R, although slightly reduced amount of the mutant CREG was detected in M6P/IGF2R immunoprecipitates.Immunostaining revealed that His-tagged CREGs co-localized with IGF2R on the cell surface in a glycosylation-independent manner.In vitro binding assay showed that CREGs bound to M6P/ IGF2R extracellular domains 7-10 and 11-13 in a glycosylation -dependent and -independent manner,respectively.Further blocking experiments using soluble M6P/IGF2R fragments and M6P/IGF2R neutralizing antibody indicated that the biological activities of recombinant CREGs in SMC growth and the up-regulation of SMC differentiation markers were all abolished by treatment with the M6P/IGF2R neutralizing antibody. However,although the growth inhibitory effect of wtCREG was nearly abolished by D7-10 or D11-13,the effect of mCREG was only reversed by Dll-13,indicating that the binding to domains 11-13 is required for CREG to modulate the proliferation of SMCs.Conclusions These data suggest that solubleCREG proteins can exert their biological function via binding to the extracellular domains 7-10 and 11-13 of cell surface M6P/IGF2R in both a glycosylation-dependent and -independent manner.展开更多
Background To investigate the effects and mechanisms of cellular repressor of ElA stimulated genes(CREG)on endothelial cell(EC)migration.Methods vascular endothelial cells(VE),CREG overexpression VEs,CREG suppression ...Background To investigate the effects and mechanisms of cellular repressor of ElA stimulated genes(CREG)on endothelial cell(EC)migration.Methods vascular endothelial cells(VE),CREG overexpression VEs,CREG suppression VEs and VEs transfected with CREG gene modified adenovirus(Ad-CREG)were cultured with dulbecco’s modified eagle’s medium contained 10%fetal calf serum.Western blot was used to detect the protein level of CREG and integrin-linked kinase(ILK)in the four kind ECs.Tran-swell migration model was applied to compare the migration cell number of the four kind ECs.Two kinds of ILK mutant plasmids;PCXN2-flag-ILK wt-IRES-GFP(wild-type ILK)and PCXN2-flag-ILK p-parvin-IRES-GFP(P-parvin-binding mutant)were used to transfect VS and VE respectively,then the two kind transfection ECs were named as VS-wtILK and VE-P-parvin which were selected by G418(600ng/ml)for 2 weeks;Transwell migration model was applied to compare migration capability before and after ILK plasmids transfecting VE and VS.Results Western blot analysis showed that CREG overexpression promoted ILK expression in ECs,on the contrary,ILK expression was down-regulated in CREG silent ECs(P【0.05).Further more,ILK expression was up-regulated obviously in VE transfected with Ad-CREG(P【0.05);Transwell migration model showed that EC’s migration capability was positively correlated with the expression level of CREG in EC,that is,CREG overexpression induced VE migration and CREG silent suppressed VE migration,moreover,Ad-CREG transfecting VE showed better migration capability accompanied with CREG expression increase by transwell migration model(P【0.05).In order to know the relationship between ILK expression and cell migration,we obtained stable transfection cell strains of VS-wtILK and VE-Pparvin,transwell migration model demonstrated that VS-wtILK remarkably corrected the poor migration capability of VS(P【0.01),butβ-parvin combining site mutation in ILK genes inhibited VE migration markedly(P【0.01).Conclusions ILKp-parvin signal pathway mediated vascular endothelial cell migration induced by CREG.展开更多
Background The CREG is an important lysosomal protein involved in a variety of cellular functions including promoting cell differentiation,sustaining mature homeostasis,and antagonizing apoptosis.Deficiency of CREG in...Background The CREG is an important lysosomal protein involved in a variety of cellular functions including promoting cell differentiation,sustaining mature homeostasis,and antagonizing apoptosis.Deficiency of CREG in cell and tissue results in a pathologic apoptosis.The present study aimed to elucidate the mechanism of CREG regulation apoptosis.Methods We firstly generated stable NIH3T3 fibroblasts by transfection of pDS_shCREGs vectors.Furthermore,PI-Annexin V and TUNEL staining were used to identify that CREG knockdown promoted the cell apoptosis in NIH3T3 fibroblasts.Western blotting and immunofluorescence staining was used to identify the expression and localization of M6P/IGF2R and cathepsin L in cytoplasm.Results pDS_shCREGs vector transfection produced an approximately 80%decrease in CREG levels both in the lysate and in the media.The expression and localization of M6P/IGF2R and cathepsin L in cytoplasma changed obviously associated with down-regulated of CREG.In addition,the retention and secretion of cathepsin L enhanced significantly.Using the specific inhibitor or siRNA to block cathepsin L activation attenuated the apoptosis mediated by CREG downregulation.Conclusions Our findings indicated that inhibition of CREG expression in NIH3T3 fibroblasts leads to impaired cathepsin L sorting function mediated by M6P/IGF2R and subsequently promotes pathological cell apoptosis.展开更多
Background Restenosis and atherosclerosis are two disorders characterized by abundant proliferation and migration of vascular smooth muscle cells(VSMCs).Previous studies have demonstrated a protective effect of the ce...Background Restenosis and atherosclerosis are two disorders characterized by abundant proliferation and migration of vascular smooth muscle cells(VSMCs).Previous studies have demonstrated a protective effect of the cellular repressor of E1A-stimulated genes(CREG)against restenosis.However,the role of CREG in atherosclerosis is undetermined.The aim of the present study is to examine the impact of CREG on the atherosclerosis.Methods Both immunofluorescence and western blotting were used in this experiment.Results The expression of CREG was decreased markedly in atherosclerotic lesions compared with normal areas of the vessels from both humans and mice species.We furthermore demonstrated that compared with the adenovirus-mediated-GFP control,intravenous administration of adenovirus-mediated CREG to apolipoprotein E deficient mice with six-week high-fat diet significantly reduced the relative area of atherosclerotic lesions in the mice aorta,accompanied by a decreased levels of Tumor necrosis factor(TNF)-αand Interleukin(IL)-1βmeasured by ELISA.Meanwhile,Western analysis revealed that NF-κB activation was also markedly reduced.Studies of cultured human VSMCs identified that overexpression of CREG abrogated the proliferation of human VSMCs stimulated by ox-LDL,along with a significantly decreased releasing of TNF-αand IL-1β.Conversely,down-regulation CREG expression contributed to cells proliferation stimulated by ox-LDL in cultured human VSMCs.Furthermore,overexpression of CREG suppressed the activations of NF-kB and ERK1/2 in cultured cells,while Furthermore,treatment with ERK inhibitor PD98059 reversed the CREG-mediated inhibition of human VSMCs proliferation.Conclusions CREG has a protective effect against atherosclerosis,which is related to inhibiting proliferation and inflammatory response of VSMCs.展开更多
Background Cellular repressor of ElA-stimulated genes(CREG) is homeostatic modulated gene,which regulate a number of cellular processes,including cell differentiation, motility and survival.Previous studies have demon...Background Cellular repressor of ElA-stimulated genes(CREG) is homeostatic modulated gene,which regulate a number of cellular processes,including cell differentiation, motility and survival.Previous studies have demonstrated that CREG was expressed in all three germ layers,suggesting that it might act as a vital regulator during embryonic developing.The aim of the present study was to investigate the role of CREG in an embryonic stem cell(ESC) differentiation model that recapitulates the developmental steps of vasculogenesis.Methods The ES cells were stably transfected either pCXN2-FLAG-CREG-IRES-EGFP plasmid or pDS1- shRNA-CREG plasmid to produce the CREG+/ES cells and CREG-siRNA/ES cells,respectively.Vasculogenesis was detected by whole mount immunostainings for CD31.Dil labeled acLDL staining assay was used to detect branching pseudopods in cultures in Matrigel.Real-time PCR and Western blot analysis were employed to determine expressions of VEGF and Flk-1.Results CREG +/ES-derived embryoid bodies(EBs) were found to form spontaneously a primitive vascular network after 6 days of differentiation.In contrast, wildtype EBs exhibit theirs vasculogenesis until 13 days of differentiation by whole mount immunostainings for CD31. CREG +/EBs developed more rapidly branching pseudopods at 9 days compared with that of wildtype EBs by Dil labeled acLDL staining assay.In contrast,CREG-siRNA/ES exhibits an undifferentiated morphogenesis associated with an increase in apoptotic cells in spite of being derived from LIF and feeder layers.Administration of CREG-siRNA/ES cells with recombinant CREG protein rescued the phenomena that CREG boosted vasculogenesis in a dose-dependent fasion. Mechanically,Real-time PCR and Western blot analysis revealed the expressions both VEGF and Flk-1 significantly in- creased in CREG+/EBs.Moreover,after treatment of CREG+ /EBs with neurtralizing antibody against VEGF,the rapid vasculogenesis was significantly repressed.Conclusions Our data strongely demonstrate that CREG play a pivotal role in accelerating vasculogenesis in development of ES cells. VEGF,as its important downstream effector,mediated this bio-function.展开更多
文摘Background The cellular repressor of ElA-stimulated genes(CREG)is a secreted glycoprotein that inhibits cell proliferation and/or enhances differentiation.CREG is widely expressed in adult tissues such as the brain,heart,lungs,liver,intestines and kidneys in mice.We investigated the level of CREG expression during mouse embryogenesis and its distribution at 18.5 days post coitus(dpc).Methods Immunohistochemical staining with diaminobenzidine,western blotting and reverse transcription-polymerase chain reaction were used.Results CREG expression was rst detected in mouse embryos at 4.5 dpc.It was expressed at almost all stages up to 18.5 dpc.The level of CREG was found to increase gradually and was highest at 18.5 dpc.Western blotting showed that the CREG protein was expressed at higher levels in the brain,heart,intestines and kidneys than in the lungs and liver at 18.5 dpc.In 9.5 dpc embryos,CREG was expressed only in the endothelial cells of blood vessels,after the vascular lumen had formed.With advanced differentiation,vascular smooth muscle cells developed in the embryonic vascular structures;the expression of smooth muscle a-actin protein and CREG were positive and increased gradually in 10.5 dpc embryonic vessels.CREG expression in the embryonic blood vessels peaked at 15.5 dpc and was reduced slightly at 18.5 dpc.Conclusions These results indicate that CREG is expressed during mouse embryogenesis and might participate in the differentiation of these organs during embryogenesis.
文摘目的:建立心肌特异性Creg基因敲除小鼠并初步分析其表型。方法:利用订购的Creg两端插入lox P位点(Cregflox/flox)的小鼠与肌型肌酸激酶特异性启动子驱动的Cre重组酶转基因(Ckmm-cre)小鼠交配,获得Cregflox/+/Ckmm-cre小鼠。再利用Cregflox/+/Ckmm-cre小鼠互相交配,获得基因型为Cregflox/flox/Ckmm-cre的心肌特异性Creg基因条件敲除(Creg conditional knockout,Creg c KO)小鼠。用PCR法进行基因型鉴定。用定量PCR及Western Blot检测心肌组织中Creg表达水平。HE染色观察敲除小鼠与同窝野生型对照小鼠心脏大小及形态。检测两组小鼠心电图。用小动物超声评价两组小鼠左心室收缩功能。结果:1经基因型鉴定,成功获得Creg c KO小鼠。2与野生型对照相比,Creg c KO小鼠心脏中CREG在转录及翻译水平表达降低90%以上。3与野生型对照相比,Cre c KO小鼠的心脏大小、形态、心电图及左心室射血分数均无显著差别。结论:成功建立心肌特异性CREG基因条件敲除小鼠,为进一步研究Creg在心脏疾病中的作用和机制提供了有力的工具。
文摘Background The present study aimed to investigate the detailed mode and specific sites for their binding as well as the functional relevance of this binding in the phenotypic proliferation of vascular smooth muscle cells(SMCs). Methods CREG knocked-down SMCs were employed to evaluate the biological activity of wtCREG and mCREG.Expressions of SMC differentiation markers SM myosin heavy chain(SM-MHC),SM-actin,heavy caldesmon and myocardin were determined by Western blotting using specific antibodies. Cellular growth of SMCs was assessed by bromide dewuridine (BrdU) incorporation and cell cycle analysis on fluorescence-activated cell sorting(FACS).A solid-phase binding assay was used to study the binding of CREG to extracellular domains of M6P/IGF2R.The cellular co-localization of the two recombinant CREGs with M6P/IGF2R was detected on SMC surface by immunoprecipitation and immunofluorescence analysis.Results The molecular weight of wtCREG was around 30 kD while that of the mCREG was～25 kD.Treatment of wtCREG with PNGase F reduced its molecular weight from～30 kD to～25 kD,whereas PNGase F treatment had no effect on the molecular weight of mCREG.Both wtCREG and mCREG proteins enhanced SMC differentiation,inhibited BrdU incorporation,and arrested cell cycle progression when added to the culture medium.In CREG knocked-down SMCs,the amount of CREG detected by immunoblotting in M6P/IGF2R immunoprecipitates was significantly reduced when compared to normal cells.Both recombinant CREGs co-immunoprecipitated with M6P/IGF2R, although slightly reduced amount of the mutant CREG was detected in M6P/IGF2R immunoprecipitates.Immunostaining revealed that His-tagged CREGs co-localized with IGF2R on the cell surface in a glycosylation-independent manner.In vitro binding assay showed that CREGs bound to M6P/ IGF2R extracellular domains 7-10 and 11-13 in a glycosylation -dependent and -independent manner,respectively.Further blocking experiments using soluble M6P/IGF2R fragments and M6P/IGF2R neutralizing antibody indicated that the biological activities of recombinant CREGs in SMC growth and the up-regulation of SMC differentiation markers were all abolished by treatment with the M6P/IGF2R neutralizing antibody. However,although the growth inhibitory effect of wtCREG was nearly abolished by D7-10 or D11-13,the effect of mCREG was only reversed by Dll-13,indicating that the binding to domains 11-13 is required for CREG to modulate the proliferation of SMCs.Conclusions These data suggest that solubleCREG proteins can exert their biological function via binding to the extracellular domains 7-10 and 11-13 of cell surface M6P/IGF2R in both a glycosylation-dependent and -independent manner.
文摘Background To investigate the effects and mechanisms of cellular repressor of ElA stimulated genes(CREG)on endothelial cell(EC)migration.Methods vascular endothelial cells(VE),CREG overexpression VEs,CREG suppression VEs and VEs transfected with CREG gene modified adenovirus(Ad-CREG)were cultured with dulbecco’s modified eagle’s medium contained 10%fetal calf serum.Western blot was used to detect the protein level of CREG and integrin-linked kinase(ILK)in the four kind ECs.Tran-swell migration model was applied to compare the migration cell number of the four kind ECs.Two kinds of ILK mutant plasmids;PCXN2-flag-ILK wt-IRES-GFP(wild-type ILK)and PCXN2-flag-ILK p-parvin-IRES-GFP(P-parvin-binding mutant)were used to transfect VS and VE respectively,then the two kind transfection ECs were named as VS-wtILK and VE-P-parvin which were selected by G418(600ng/ml)for 2 weeks;Transwell migration model was applied to compare migration capability before and after ILK plasmids transfecting VE and VS.Results Western blot analysis showed that CREG overexpression promoted ILK expression in ECs,on the contrary,ILK expression was down-regulated in CREG silent ECs(P【0.05).Further more,ILK expression was up-regulated obviously in VE transfected with Ad-CREG(P【0.05);Transwell migration model showed that EC’s migration capability was positively correlated with the expression level of CREG in EC,that is,CREG overexpression induced VE migration and CREG silent suppressed VE migration,moreover,Ad-CREG transfecting VE showed better migration capability accompanied with CREG expression increase by transwell migration model(P【0.05).In order to know the relationship between ILK expression and cell migration,we obtained stable transfection cell strains of VS-wtILK and VE-Pparvin,transwell migration model demonstrated that VS-wtILK remarkably corrected the poor migration capability of VS(P【0.01),butβ-parvin combining site mutation in ILK genes inhibited VE migration markedly(P【0.01).Conclusions ILKp-parvin signal pathway mediated vascular endothelial cell migration induced by CREG.
文摘Background The CREG is an important lysosomal protein involved in a variety of cellular functions including promoting cell differentiation,sustaining mature homeostasis,and antagonizing apoptosis.Deficiency of CREG in cell and tissue results in a pathologic apoptosis.The present study aimed to elucidate the mechanism of CREG regulation apoptosis.Methods We firstly generated stable NIH3T3 fibroblasts by transfection of pDS_shCREGs vectors.Furthermore,PI-Annexin V and TUNEL staining were used to identify that CREG knockdown promoted the cell apoptosis in NIH3T3 fibroblasts.Western blotting and immunofluorescence staining was used to identify the expression and localization of M6P/IGF2R and cathepsin L in cytoplasm.Results pDS_shCREGs vector transfection produced an approximately 80%decrease in CREG levels both in the lysate and in the media.The expression and localization of M6P/IGF2R and cathepsin L in cytoplasma changed obviously associated with down-regulated of CREG.In addition,the retention and secretion of cathepsin L enhanced significantly.Using the specific inhibitor or siRNA to block cathepsin L activation attenuated the apoptosis mediated by CREG downregulation.Conclusions Our findings indicated that inhibition of CREG expression in NIH3T3 fibroblasts leads to impaired cathepsin L sorting function mediated by M6P/IGF2R and subsequently promotes pathological cell apoptosis.
文摘Background Restenosis and atherosclerosis are two disorders characterized by abundant proliferation and migration of vascular smooth muscle cells(VSMCs).Previous studies have demonstrated a protective effect of the cellular repressor of E1A-stimulated genes(CREG)against restenosis.However,the role of CREG in atherosclerosis is undetermined.The aim of the present study is to examine the impact of CREG on the atherosclerosis.Methods Both immunofluorescence and western blotting were used in this experiment.Results The expression of CREG was decreased markedly in atherosclerotic lesions compared with normal areas of the vessels from both humans and mice species.We furthermore demonstrated that compared with the adenovirus-mediated-GFP control,intravenous administration of adenovirus-mediated CREG to apolipoprotein E deficient mice with six-week high-fat diet significantly reduced the relative area of atherosclerotic lesions in the mice aorta,accompanied by a decreased levels of Tumor necrosis factor(TNF)-αand Interleukin(IL)-1βmeasured by ELISA.Meanwhile,Western analysis revealed that NF-κB activation was also markedly reduced.Studies of cultured human VSMCs identified that overexpression of CREG abrogated the proliferation of human VSMCs stimulated by ox-LDL,along with a significantly decreased releasing of TNF-αand IL-1β.Conversely,down-regulation CREG expression contributed to cells proliferation stimulated by ox-LDL in cultured human VSMCs.Furthermore,overexpression of CREG suppressed the activations of NF-kB and ERK1/2 in cultured cells,while Furthermore,treatment with ERK inhibitor PD98059 reversed the CREG-mediated inhibition of human VSMCs proliferation.Conclusions CREG has a protective effect against atherosclerosis,which is related to inhibiting proliferation and inflammatory response of VSMCs.
文摘Background Cellular repressor of ElA-stimulated genes(CREG) is homeostatic modulated gene,which regulate a number of cellular processes,including cell differentiation, motility and survival.Previous studies have demonstrated that CREG was expressed in all three germ layers,suggesting that it might act as a vital regulator during embryonic developing.The aim of the present study was to investigate the role of CREG in an embryonic stem cell(ESC) differentiation model that recapitulates the developmental steps of vasculogenesis.Methods The ES cells were stably transfected either pCXN2-FLAG-CREG-IRES-EGFP plasmid or pDS1- shRNA-CREG plasmid to produce the CREG+/ES cells and CREG-siRNA/ES cells,respectively.Vasculogenesis was detected by whole mount immunostainings for CD31.Dil labeled acLDL staining assay was used to detect branching pseudopods in cultures in Matrigel.Real-time PCR and Western blot analysis were employed to determine expressions of VEGF and Flk-1.Results CREG +/ES-derived embryoid bodies(EBs) were found to form spontaneously a primitive vascular network after 6 days of differentiation.In contrast, wildtype EBs exhibit theirs vasculogenesis until 13 days of differentiation by whole mount immunostainings for CD31. CREG +/EBs developed more rapidly branching pseudopods at 9 days compared with that of wildtype EBs by Dil labeled acLDL staining assay.In contrast,CREG-siRNA/ES exhibits an undifferentiated morphogenesis associated with an increase in apoptotic cells in spite of being derived from LIF and feeder layers.Administration of CREG-siRNA/ES cells with recombinant CREG protein rescued the phenomena that CREG boosted vasculogenesis in a dose-dependent fasion. Mechanically,Real-time PCR and Western blot analysis revealed the expressions both VEGF and Flk-1 significantly in- creased in CREG+/EBs.Moreover,after treatment of CREG+ /EBs with neurtralizing antibody against VEGF,the rapid vasculogenesis was significantly repressed.Conclusions Our data strongely demonstrate that CREG play a pivotal role in accelerating vasculogenesis in development of ES cells. VEGF,as its important downstream effector,mediated this bio-function.
