and Eleanor N. Fish
Olivia Chan, J. Daniel Burke, Darrin F. Gao
Activated T Cells to Facilitate Chemotaxis Uptake and AMP Kinase Signaling in The Chemokine CCL5 Regulates Glucose Metabolism:
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The Chemokine CCL5Regulates Glucose Uptake and AMP Kinase Signaling in Activated T Cells to Facilitate Chemotaxis *□
S
Received for publication,February 1,2012,and in revised form,July 6,2012Published,JBC Papers in Press,July 10,2012,DOI 10.1074/jbc.M112.348946
Olivia Chan,J.Daniel Burke,Darrin F.Gao,and Eleanor N.Fish 1
From the Toronto General Research Institute,University Health Network and Department of Immunology,University of Toronto,Toronto,Ontario M5G 2M1,Canada
Recruitment of effector T cells to sites of infection or inflam-mation is essential for an effective adaptive immune response.The chemokine CCL5(RANTES)activates its cognate receptor,CCR5,to initiate cellular functions,including chemotaxis.In earlier studies,we reported
that CCL5-induced CCR5signaling activates the mTOR/4E-BP1pathway to directly modulate mRNA translation.Specifically,CCL5-mediated mTOR activa-tion contributes to T cell chemotaxis by initiating the synthesis of chemotaxis-related proteins.Up-regulation of chemotaxis-related proteins may prime T cells for efficient migration.It is now clear that mTOR is also a central regulator of nutrient sens-ing and glycolysis.Herein we describe a role for CCL5-mediated glucose uptake and ATP accumulation to meet the energy demands of chemotaxis in activated T cells.We provide evi-dence that CCL5is able to induce glucose uptake in an mTOR-dependent https://www.doczj.com/doc/5610670117.html,L5treatment of ex vivo activated human CD3?T cells also induced the activation of the nutrient-sensing kinase AMPK and downstream substrates ACC-1,PFKFB-2,and GSK-3?.Using 2-deoxy-D -glucose,an inhibitor of glucose uptake,and compound C,an inhibitor of AMPK,experimental data are presented that demonstrate that CCL5-mediated T cell chemotaxis is dependent on glucose,as these inhibitors inhibit CCL5-mediated chemotaxis in a dose-dependent manner.Alto-gether,these findings suggest that both glycolysis and AMPK signaling are required for efficient T cell migration in response to CCL5.These studies extend the role of CCL5mediated CCR5signaling beyond lymphocyte chemotaxis and demonstrate a role for chemokines in promoting glucose uptake and ATP pro-duction to match energy demands of migration.
Chemokines are chemotactic cytokines responsible for orchestrating leukocyte migration.Chemokine binding to spe-
cific seven transmembrane-spanning G protein-coupled recep-tors initiates signaling cascades that promote directional migration through cytoskeletal rearrangement,cell polariza-tion,and integrin activation (1,2).Indeed,efficient T cell roll-ing,adhesion,and transmigration through blood vessels are imperative for an effective immune response (2–4).It is now clear that chemokines also regulate numerous migration-unre-lated responses,including survival,apoptosis,mRNA transla-tion,angiogenesis,and tumor growth (5–11).
CCL5(RANTES)is a proinflammatory chemokine that reg-ulates the trafficking of Th1T cells,macrophages,dendritic cells,and natural killer cells,mediated by activation of the receptors CCR1,CCR3,and/or CCR5(12–14).CCL5engage-ment with its cognate receptor,CCR5,results in the rapid up-regulation of mRNA translation of chemotaxis-related proteins in primary CD4?T cells,as well as prosurvival factors in MCF-7breast cancer cells (7,8).Inhibition studies with the PI3K inhibitor LY294002and the mTOR 2inhibitor rapamycin have underscored the importance of CCL5activation of PI3K/mTOR signaling to induce protein https://www.doczj.com/doc/5610670117.html,L5-mediated activation of CCR5leads to the phosphorylation and deactiva-tion of the translational repressor 4E-BP1in a PI3K/mTOR-de-pendent manner,which results in the subsequent release of eukaryotic initiation factor-4E (eIF4E)(8).eIF4E binds the mRNA 5?-cap structure together with other initiation factors to form the eIF4F complex,responsible for mRNA unwind-ing and ribosomal binding during mRNA translation (15).The evolutionarily conserved mTOR is a serine/threonine kinase that exists as two complexes:the mTOR complex 1(mTORC1),which is rapamycin-sensitive,and mTOR complex 2(mTORC2),which is rapamycin-insensitive.It is mTORC1that senses and integrates extrinsic signals to positively regulate cellular proliferation and metabolism in addition to lympho-cyte migration and cap-dependent mRNA translation (16–18).
*This work was supported by Natural Sciences and Engineering Research
Council of Canada Grant 278397.
□S
This article contains supplemental Fig.1.1
A Tier 1Canada Research Chair.To whom correspondence should be addressed:Toronto General Research Institute,67College Street,Rm.4-424,Toronto ON M5G 2M1,Canada.Tel.:416-340-5380;Fax:416-340-3453;E-mail:en.fish@utoronto.ca.
2
The abbreviations used are:mTOR,mammalian target of rapamycin;2-DG,
2-deoxy-D -glucose;ACC-1,acetyl-CoA carboxylase 1;AMPK,AMP-acti-vated protein kinase;GLUT,glucose transporter;GSK-3?,glycogen syn-thase kinase-3?;PB,peripheral blood;PFKFB-2,6-phosphofructo-2-ki-nase/fructose-2,6-biphosphatase 2.
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mTORC1directly regulates the surface expression of a num-ber of nutrient receptors,namely,the amino acid transporter CD98(4F2HC),the transferrin receptor,and the low-density
lipoprotein receptor in response to Akt activation (16).Cyto-kine-induced glucose uptake is Akt/mTOR-dependent,and rapamycin treatment decreases glycolytic rates in FL5.12pro-B cells (19).Akt signaling plays a pivotal role in increasing T cell metabolism in response to immune stimulation by increasing glucose and amino acid uptake (16,20–22).Another important sensor of cellular energy is the AMP-activated protein kinase (AMPK)(23–26).During nutrient deprivation or hypoxia,when intracellular levels of ATP decline and AMP levels rise,AMPK is activated.Active AMPK is responsible for initiating alternative energy-generating processes such as fatty acid oxi-dation,and inhibition of energy-consuming processes,includ-ing cell cycling and biosynthesis (23,27,28).
Given that CCL5-CCR5interactions induce mTOR/4E-BP1signaling associated with energy-consuming processes such as mRNA translation and chemotaxis (15),we undertook studies to examine whether CCL5/mTOR signaling may contribute to energy generation to support the high energy demands of acti-vated T cells.We provide evidence that at concentrations that support chemotaxis,CCL5enhances glucose uptake and ATP levels of activated T cells.Specifically,our data indicate that CCL5simultaneously activates AMPK and mTOR signaling cascades to regulate glucose uptake and chemotaxis in acti-vated T cells.This is the first report that provides evidence for a chemokine,CCL5,regulating metabolic intermediates,glucose and ATP,to facilitate efficient chemotaxis.
EXPERIMENTAL PROCEDURES
Cells and Reagents —Human peripheral blood (PB)-derived T lymphocytes were isolated from consenting healthy donors,as per a protocol approved by the University Health Network Research Ethics Board.Cells were maintained in RPMI 1640medium supplemented with 10%dialyzed fetal calf serum (Sigma),100units/ml penicillin,100mg/ml streptomycin and 2m M L -glutamine (Invitrogen).CD3?T cells were purified using the StemSep T cell enrichment mixture according to the man-ufacturer’s specifications (StemCell Technologies).T cells were subsequently activated in Microwell plates coated with 10?g/ml anti-CD3antibody (eBiosciences),5?g/ml anti-CD28antibody (eBiosciences),and 5ng/ml human recombinant IL-12(Bioshop)for 2days and further expanded in culture sup-plemented with 100units/ml human recombinant IL-2(Bio-shop)every other day for 3days.To avoid confounding data attributed to IL-2effects,PB T cells that were used for CCL5treatment experiments were stimulated with IL-2on days 2and 4,and then CCL5was treated on day 6without IL-2stimula-tion.Cultures that served as positive controls were stimulated with IL-2on days 2,4,and 6.T cell purity and CCR5expression were confirmed on day 6by flow cytometric analysis using anti-human CD3antibody,anti-human CD4,anti-human CD8(eBiosciences)and anti-human CCR5antibodies (2D7,BD Pharmingen;CD195,BD Bioscience)(supplemental Fig.1).Antibodies for phospho-AMPK-?(Thr-172),AMPK-?,phos-pho-GSK-3?(Ser-9),phospho-4E-BP1(Thr-37/46),and 4E-BP1,were purchased from Cell Signaling Technology.
Mouse monoclonal anti-?-tubulin antibody was purchased from R&D Systems.Purified mouse anti-human CD98(4F2HC)and GLUT-1antibodies were obtained from Santa Cruz Biotechnology and R&D Systems,respectively.Inhibitors rapamycin and compound C were obtained from Calbiochem.The ATP bioluminescent assay kit,2-deoxy-D -glucose,and oligomycin were purchased from https://www.doczj.com/doc/5610670117.html,L5was a generous gift from Dr.Amanda Proudfoot (Geneva Research Centre,Merck Serono Intl.).The CCR5antagonist,TAK-779,was kindly provided by Dr.Clifford Lingwood (University of Toronto,Sickkids Hospital).
Immunoblotting —Cells were incubated with 10n M CCL5for the times indicated,washed twice with ice-cold PBS and lysed in 100?l of lysis buffer (1%Triton X-100,0.5%Nonidet P-40,150m M NaCl,10m M Tris-HCl,pH 7.4,1m M EDTA,1m M EGTA,0.2m M PMSF,10?g/ml aprotinin,2?g/ml leupeptin,2?g/ml pepstatin A).For all experiments using inhibitors or acti-vators,cells were pretreated for 1h with the indicated com-pound prior to CCL5treatment.Protein concentration was determined using the Bio-Rad DC protein assay kit (Bio-Rad).50?g of each protein lysate was denatured in Laemmli sample reducing buffer,and proteins were resolved by SDS-PAGE.The separated proteins were transferred to a nitrocellulose mem-brane followed by blocking with 5%BSA (w/v)in 1?TBST (0.1%Tween 20)for 1h at room temperature.Membranes were probed with the specified antibodies overnight in 5%BSA (w/v)in TBST at 4°C and the respective proteins visualized using the ECL detection system (Pierce).
Flow Cytometric Analysis —1?106cells were incubated with mouse anti-human CCR5antibody for 30min on ice and washed twice with ice-cold FACS buffer (PBS/2%FCS).Cells were then incubated with Alexa Fluor 488-conjugated anti-mouse IgG antibody (eBiosciences).As a control,cells were incubated with Alexa Fluor 488-conjugated antibody alone.T cell purity was determined by incubating cells with a phyco-erythrin-conjugated anti-human CD3antibody.As an isotype control,cells were incubated with phycoerythrin-labeled iso-type control IgG antibody (eBiosciences).For GLUT-1and CD98(4F2HC)surface expression,cells were washed twice with ice-cold FACS buffer and fixed with 2%paraformaldehyde at room temperature for 20min.Cells were then washed twice with FACS buffer and incubated with mouse anti-human GLUT-1antibody or mouse anti-human CD98antibody for 30min on ice.Cells were then washed twice and incubated with Alexa Fluor 488-conjugated anti-mouse IgG antibody.Cells were analyzed using the FACSCalibur and FlowJo software (BD Biosciences).
Chemotaxis Assay —T cell chemotaxis was assayed using 24-well Transwell chambers with 5-?m pores (Corning).1?105cells in 100?l of chemotaxis buffer (RPMI 1640/0.5%BSA)were placed in the upper https://www.doczj.com/doc/5610670117.html,L5,diluted in 600?l of chemotaxis buffer,was placed in the lower wells,and the cham-bers were incubated for 2h at 37°C.Cells that migrated to the bottom wells were collected and counted with a hemocytome-ter.For experiments involving inhibitors,cells were pretreated for 1h with the indicated inhibitor and then placed in the upper chambers.Cell viability,as measured by propidium iodide
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staining,was not affected by any of the doses of inhibitors used in this study (data not shown).
Glucose Uptake Assay —3–5?106cells were washed with PBS and resuspended in 500?l of Krebs-Ringer-HEPES (KRH)(at pH 7.4,136m M NaCl,4.7m M KCl,1.25m M CaCl 2,1.25m M MgSO 4,and 10m M HEPES).2-Deoxy-D -[H 3]glucose (2?Ci/reaction;PerkinElmer Life Sciences)was added in the presence of CCL5,and the reaction mixture was incubated at 37°C.Reactions were quenched by the addition of ice-cold KRH con-taining 200?M phloretin (Calbiochem),followed by immediate centrifugation through an oil layer (1:1phthalic acid and dibut-lylpthalate from Sigma-Aldrich).Cell pellets were washed and solubilized in 1M NaOH for 1h,and radioactivity was measured using a liquid scintillation counter.In experiments involving inhibitors,cells were pretreated for 1h before the addition of 2-deoxy-D -[3H]glucose and CCL5.
AMPK Signaling Antibody Array —Phosphorylation events in the AMPK signaling pathway were examined using the Full Moon BioSystems Antibody Microarray,according to the man-ufacturer’s specifications (Full Moon BioSystems,Inc.)Briefly,5?106cells were stimulated with CCL5for 10min,washed with ice-cold PBS,and lysed with 200?l of extraction buffer.Protein samples were biotinylated,then added to a microscope slide chamber with specific antibodies bound to its surface.Cy3-streptavidin was added,and fluorescence was detected using the Axon GenePix 400A Microarray Scanner at PMT voltages between 300–400(Molecular Devices).
ATP Bioluminescent Assay —Intracellular ATP levels were examined using the ATP bioluminescent assay kit,according to the manufacturer’s protocol (Sigma-Aldrich).2?105cells were either left untreated or pretreated with compound C,2-DG,or oligomycin prior to stimulation with CCL5.Cells were permeabilized using somatic cell ATP releasing agent and sub-sequently added to an ATP assay mix containing luciferin.Bio-luminescence was measured using a VICTOR TM X3Multilabel Plate Reader (PerkinElmer Life Sciences).
Statistical Analysis —Statistical significance was analyzed with repeated-measures analysis of variance.A level of p ?0.05was chosen to identify significant differences.All data are expressed as mean ?S.E.
RESULTS
CCL5Induces Phosphorylation of Proteins in the AMPK Sig-naling Pathway —To investigate potential metabolic changes induced by CCL5in activated T cells,we initially undertook a global screening approach for phosphorylation events examin-ing the energy-sensing,AMPK signaling pathway.We employed an antibody microarray platform that measures the phosphorylation of upstream and downstream substrates of AMPK.At the outset,we confirmed that ex vivo cytokine acti-vation of PB CD3?T cells induced cell surface expression of
CCR5in a predominant CD4?cell population (supplemental Fig.1).
Activated PB T cells were either left untreated or treated with 10n M CCL5for 10min,the cells lysed,and the proteins were biotinylated,as described under “Experimental Procedures.”Biotinylated proteins were then introduced into the microarray slide chambers conjugated with antibodies specific for the AMPK signaling cascade,and T cell-derived proteins were identified using a Cy3-streptavidin detection system.The microarray slide images generated are shown in Fig.1A and phosphorylation quantitation in Fig.1B .The data reveal that CCL5treatment of T cells resulted in the rapid phosphorylation of a number of signaling effectors in the AMPK signaling path-way,as well as effectors in the PI3K/Akt and mTOR/4E-BP1cascades.Notably,CCL5induced the phosphorylation of PFKFB-2(6-phosphofructo-2-kinase/fructose-2,6-biphospha-tase 2or PFK-2),a positive regulator of glycolysis,ACC-1(acetyl-CoA carboxylase 1),an enzyme important for fatty acid synthesis and inhibitor of fatty acid oxidation,and the master regulators of energy status:LKB1,AMPK1/AMPK2,and mTOR.
To validate the antibody array findings for AMPK,Western immunoblot time course studies were https://www.doczj.com/doc/5610670117.html,L5induced maximal phosphorylation of AMPK-?on Thr-172by 10min (Fig.2A ).Phosphorylation of Thr-172is absolutely required for AMPK activation (24,29).CCL5also induced the phosphorylation of GSK-3?(glycogen synthase kinase 3?),a downstream substrate of AMPK,on Ser-9,with peak phosphor-ylation detected at 10min post-CCL5treatment (Fig.2A ).GSK-3?is a constitutively active serine/threonine kinase that regulates glycogen synthesis,gene transcription,mRNA trans-lation,and cell proliferation.In its phosphorylated/inactive form,GSK-3?derepresses/releases downstream signaling mediated by glycogen synthase,eIF2B,NF-?B,and other down-stream substrates (30–32).Thus,the inhibitory effect of CCL5treatment on GSK-3?may regulate glycogen storage and other transcriptional events in activated T cells.During energetic stress,active AMPK is able to switch on catabolic processes that generate ATP (33–35).To confirm the effects of CCL5on AMPK activation and subsequent ATP generation,we evalu-ated intracellular ATP levels post-CCL5treatment.Consistent with a maximal activation of AMPK at 10min post-CCL5treat-ment,CCL5treatment induced maximal intracellular accumu-lation of ATP by 30min (Fig.2B ).As a negative control,the AMPK inhibitor,compound C,was used to pretreat PB T cells prior to CCL5stimulation.As predicted,compound C-treated cells exhibited significantly reduced intracellular ATP produc-tion at both 15and 30min following CCL5treatment.These data suggest a role for CCL5in positively regulating ATP levels in an AMPK-dependent manner.Additionally,to measure the relative CCL5-dependent contributions of oxidative phosphor-
FIGURE https://www.doczj.com/doc/5610670117.html,L5induces phosphorylation of proteins in the AMPK signaling pathway.A ,the Full Moon BioSystems AMPK signaling phospho-specific antibody array includes six replicates (vertical columns)of phospho-specific antibodies and their non-phospho pairs,targeted against proteins in the AMPK signaling pathway.Biotinylated protein lysates were added to microscope slide chambers and fluorescence from Cy3-streptavidin was measured with the Axon GenePix 400A microarray scanner.B ,the extent of protein phosphorylation (mean fluorescence intensity,MFI )was normalized within each slide and compared between untreated control and cells treated with 10n M CCL5for 10min.The data are represented as fold CCL5-induction relative to untreated controls.Phosphorylated signaling intermediates associated with metabolism are indicated (red arrows ).
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ylation and glycolysis on ATP production,activated PB T cells were pretreated with the inhibitors oligomycin or2-DG prior to CCL5.A marked reduction in ATP generation induced by 2-DG and not oligomycin suggests that CCL5inducible ATP generation is predominantly mediated by glycolysis(Fig.2C). CCL5Induces Glucose Uptake That Is mTOR-dependent—AMPK not only functions to initiate ATP regeneration but also induces glucose uptake during energy stress(36).The nutrient-sensitive mTOR likewise responds to nutrient signals to regu-late glycolysis(15,18,24,25).As shown in Fig.3A,CCL5treat-ment of activated T cells resulted in a modest increase in glucose uptake in a dose-dependent manner,with maximal uptake at10n M of CCL5(1.2–1.4-fold increase).As anticipated, IL-2treatment of these activated T cells also resulted in a1.5–1.9-fold increase in glucose uptake(22).The specific contribu-tion of mTOR signaling to the CCL5-mediated increase in glu-cose uptake was examined using rapamycin.Inhibition of mTOR by rapamycin effectively reduced CCL5-mediated glu-cose uptake(Fig.3B).Finally,to confirm that CCL5specifically induces glucose uptake through CCR5activation,the CCR5 antagonist TAK-779was employed.A marked reduction in glu-cose uptake was observed in T cells pretreated with TAK-779 (Fig.3C).These data indicate that CCL5binding to CCR5,and not CCR1or CCR3,is required for glucose uptake.
CCL5Prolongs Cell Surface Expression of GLUT-1and CD98 on Activated T Cells—The ability of CCL5to stimulate glucose uptake may be facilitated through enhanced surface expression of nutrient receptors.Glucose uptake is mediated by a family of facilitative,integral membrane glucose transporters(GLUTs) that are expressed on the cell surface.In lymphocytes,facili-tated diffusion is primarily mediated by GLUT-1,a ubiqui-tously expressed glucose transporter that is up-regulated upon CD3/CD28ligation(37,38).Activated lymphocytes also increase expression of the insulin-sensitive GLUT-3and GLUT-4receptors,albeit to a lesser degree.Numerous growth signals mediate cell-surface trafficking of GLUT-1through the PI3K/Akt pathway,thereby increasing glucose uptake and gly-colytic flux(22,37–39).Another key nutrient receptor that is regulated by this pathway is CD98,the heavy chain component of the amino acid-transporter complex(40).Accordingly,we examined the ability of CCL5to regulate the surface expression of GLUT-1and CD98.
Whereas na?ve T cells express low levels of GLUT-1and CD98(Fig.4,A and B),their cell surface expression is strongly induced upon T cell activation.In time course studies,we observe that CCL5treatment did not further increase GLUT-1 or CD98expression at2,4,6,and8h post CCL5treatment(data not shown),with evidence of modest enhanced expression only by24h post-treatment(Fig.4,C and D).
Glucose Uptake and AMPK Signaling Are Required for Effi-cient CCL5-mediated Chemotaxis—Lymphocyte chemotaxis is an energy-taxing process that requires extensive cytoskeletal rearrangements in response to a migration-promoting agent. To investigate the importance of CCL5-mediated glucose uptake in T cell chemotaxis,inhibition studies were performed using the glucose analog,2-DG,which effectively inhibits gly-colysis.As shown in Fig.5A,2-DG pretreatment reduced T cell chemotaxis invoked by CCL5treatment.These data suggest that efficient chemotaxis requires a steady supply of glucose, which may contribute to CCL5-mediated migration of T lym-phocytes.Next,the role of AMPK signaling was evaluated in chemokine-induced chemotaxis.We examined the effects of the AMPK inhibitor,compound C,on CCL5-mediated T cell migration.The data reveal that AMPK inhibition reduced CCL5-inducible T cell chemotaxis(Fig.5B).The reduction in CCL5-mediated chemotaxis by the inhibitors,2-DG and com-pound C,at the doses employed,was not due to any cytotoxic effects(data not shown).
DISCUSSION
T cell migration to sites of infection or inflammation is crit-ical for an effective immune response and is a highly organized process coordinated by chemokines.Inflammatory chemo-kines bind to the glycosaminoglycans on the surface of endo-thelial cells and guide recently activated T cells toward the site of infection/inflammation by triggering adhesion and subse-quent diapedesis(41–43).In addition to promoting lympho-cyte trafficking,chemokine activation of their cognate recep-tors invokes a variety of signaling cascades in target cells that can result in diverse biological outcomes.Herein,we report on CCL5inducible signaling events in activated T cells that influ-ence the metabolic intermediates glucose and ATP.
Initial studies investigated the activation of AMPK,the het-erotrimeric energy-sensing kinase that is activated under con-ditions of energy https://www.doczj.com/doc/5610670117.html,L5induced the rapid phosphoryla-tion/activation of Thr-172in the AMPK activation loop,in addition to the phosphorylation of a number of downstream substrates including ACC-1,PFKFB-2,and GSK-3?.CCL5may simultaneously stimulate processes that increase intracellular nutrient and energy levels,while suppressing cell growth and biosynthetic processes through AMPK activation.Certainly, active AMPK acutely inhibits fatty acid and cholesterol synthe-sis by phosphorylating and inactivating metabolic enzymes ACC-1,SREBP-1,and HMG-CoA reductase in various tissues (28,44,45).Active AMPK is also able to stimulate glycolysis through GLUT trafficking and phosphorylation/activation of the glycolytic enzyme,PFKFB-2(23,28).Here,CCL5-mediated phosphorylation of ACC-1may prevent lipid synthesis as a
https://www.doczj.com/doc/5610670117.html,L5activates the energy-sensing kinase AMPK and the downstream substrate GSK-3?resulting in an increased intracellular ATP levels. A,activated PB T cells were either left untreated or treated with10n M CCL5for the indicated times.Cells were harvested and protein lysates resolved by SDS-PAGE and immunoblotted with anti-phospho-AMPK?(Thr-172)or anti-phospho-GSK-3?(Ser-9)antibodies.Membranes were stripped and reprobed for loading.Relative phosphorylation is shown as signal intensity over loading control.Data are representative of two independent experiments.B,activated PB T cells were either treated with dimethyl sulfoxide or10?M compound C for1h before treatment with10n M CCL5for the indicated times.Intracellular ATP was measured using a bioluminescent assay.Data are representative of two independent experiments.*,p?0.01;**,p?0.05.C,activated PB T-cells were pretreated with dimethyl sulfoxide(DMSO;carrier control),oligomycin(1?M),or2-deoxy-glucose(10m M)for30min and then stimulated with IL-2(20ng/ml) or CCL5(10n M)for30min.Intracellular ATP levels were then measured using a bioluminescent assay.Data are representative of two independent experiments. *,p?0.01.
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https://www.doczj.com/doc/5610670117.html,L5-mediated glucose uptake is mTOR-dependent.A,activated PB T cells were either left untreated,treated with20ng/ml IL-2,or the indicated doses of CCL5for2h.In parallel,cells were pretreated with10m M of2-DG for1h prior to treatment with10n M CCL5.At time0,2?Ci/rxn of2-deoxy-D-[3H] glucose was added to the cultures.Reactions were quenched and radioactivity measured with a liquid scintillation counter.Data are representative of three independent studies.B,cells were pretreated with either dimethyl sulfoxide(DMSO;carrier)or50n M of rapamycin for1h prior to treatment with10n M CCL5. Tritiated glucose uptake was measured as in A.Data are representative of two independent studies.C,cells were pretreated with CCR5antagonist,TAK-779for 1h prior to treatment with10n M CCL5.Tritiated glucose uptake was measured as in A.
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means to conserve energy.In addition,CCL5-mediated increases in intracellular ATP may,in part,be a consequence of increasing Fru-2,6-BP activity and thus glycolysis.
We observed that CCL5was able to promote ATP accumu-lation in an AMPK-dependent manner.Consistent with the published literature,changes in intracellular ATP are generally modest.For example,Plas and colleagues (46)report an ?4%increase in ATP in cells overexpressing Akt compared with cells expressing Bcl-x L ,and this small change was attributed to the Akt cells being more metabolically active.Importantly,small changes in metabolic parameters are sufficient to lead to signif-icant physiological changes.
Our studies show that CCL5is able to promote glucose uptake in an mTOR-dependent manner,although this increase is not accompanied by changes in surface levels of GLUT-1or CD98.Glucose transport across the plasma membrane of lym-phocytes is mediated by specific GLUT proteins:GLUT-1is responsible for basal glucose transport,whereas GLUT-3and GLUT-4regulate glucose uptake in response to insulin stimu-lation (47).Upon activation,lymphocytes make an important metabolic switch from oxidative phosphorylation to aerobic glycolysis for ATP generation (37,48,49).Consistent with this,our data also suggest ATP production to be more dependent upon glycolysis,as indicated by a greater sensitivity to treat-ment with 2-DG than oligomycin,an inhibitor of oxidative phosphorylation.CD3/CD28ligation is able to stimulate glu-cose transport,increase GLUT-1surface expression,and pro-mote glycolysis via PI3K/Akt signaling.Intriguingly,increased glucose transport can be detected well before increased GLUT-1expression,suggesting that enhanced nutrient uptake is not necessarily accompanied by a concomitant increase in transporter expression (49).Several studies in muscle cells,adi-FIGURE https://www.doczj.com/doc/5610670117.html,L5prolongs cell surface expression of GLUT-1and CD98.Activated PB T cells were either left untreated or treated with 10n M CCL5or 20ng/ml IL-2for 24h.Cells were fixed with 2%paraformaldehyde and stained for cell surface GLUT-1(A and C )or CD98(B and D )expression and analyzed by FACS.
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pose tissues,and diabetic models have also demonstrated that hormone-induced changes in glucose uptake can occur without affecting glucose transporter expression and translocation (50–52).The CCL5-stimulated glucose uptake in the absence of enhanced GLUT-1expression that we observe suggests that CCL5may promote GLUT-1intrinsic activity to facilitate glu-cose uptake.
As mentioned,mTORC1integrates numerous nutrient sig-nals to regulate metabolism,growth,migration,and protein synthesis(19,53).Wieman and colleagues(19)demonstrated that IL-3-dependent hematopoietic FL5.12cells activate the PI3K/Akt/mTOR pathway following IL-3treatment to stimu-late glucose uptake and GLUT-1trafficking.Interestingly, mTORC1activity was not required to maintain GLUT-1sur-face expression,although inhibition of mTORC1greatly dimin-ished IL-3-mediated glucose uptake.These data suggest that mTOR signaling may only be required to promote GLUT-1 functionality to enhance glucose uptake.In agreement,we observe that CCL5is also able to induce glucose uptake in an mTOR-dependent manner.Although rapamycin reduced CCL5-mediated glucose uptake,this reduction was less than that observed for2-DG.This may be attributed to other mTORC1-independent mechanisms,including the MAP kinases p38,ERK1/2,and other AMPK-signaling effector mol-ecules(51,54,55).
To investigate whether glucose uptake was required for CCL5-mediated chemotaxis,the non-metabolized glucose ana-log,2-DG,was employed.2-DG is a potent inhibitor of glycol-ysis and ATP production and has been examined as a chemo-therapeutic agent(56).Prolonged2-DG treatment in various cancer cell lines interferes with glycolysis,contributing to decreased cell growth,decreased clonogenictiy,and enhanced apoptosis through caspase-3release.Notably,our chemotactic studies using2-DG avoided prolonged drug exposure and avoided cell toxicity(data not shown).We provide evidence that glucose uptake inhibition by2-DG pretreatment reduces CCL5-inducible ATP production and reduced the ability of T cells to migrate toward a CCL5gradient in a dose-dependent manner.Proliferating lymphocytes depend on growth factor signals to promote glucose uptake to maintain survival.Even in the presence of alternative energy sources,such as glutamine,T cells maintained in glucose-free medium fail to proliferate, underscoring the non-redundant role of glucose in supporting T cell viability(57).In the present study,the inability of effector T cells to take up glucose affected migration as well.Indeed, tumor cell metastasis to secondary sites in response to a che-moattractant is also dependent on active glycolysis(58,59). For optimal T cell migration orchestrated by CCL5,we hypothesized that AMPK stimulation of ATP-generating pro-cesses may be https://www.doczj.com/doc/5610670117.html,L5-mediated T cell chemotaxis was examined following AMPK inhibition by compound C.Herein, compound C pretreatment reduced CCL5-mediated che-motaxis in a dose-dependent manner,suggesting that T cell migration in response to CCL5is partially dependent on AMPK signaling.Importantly,although AMPK is most well known for its role as an energy sensor,AMPK signaling also regulates cell polarity,actin polymerization,and directional cell migration (60–62).AMPK inhibition by compound C may prevent pro-cesses that directly promote CCL5-mediated chemotaxis and indirectly affect ATP generation.Together,these data suggest that both glucose uptake and AMPK signaling have roles in efficient T cell migration.
The present study has identified AMPK as a novel down-stream substrate of CCL5signaling in activated T cells.In addi-tion,we have identified a role for CCL5-mediated mTOR sig-naling in promoting glucose uptake and for CCL5in generating ATP production.Collectively,CCL5may simultaneously induce signaling in both the mTORC1and AMPK pathways. Intriguingly,the current literature indicates that AMPK activa-tion during energy deprivation indirectly suppresses mTOR activity by phosphorylating/activating TSC2or directly inacti-vates mTOR by targeting its Raptor subunit(24).Data gener-ated herein suggest that CCL5is able to activate both pathways simultaneously in T cells;we infer that mTOR-dependent pro-cesses such as mRNA translation and chemotaxis are energy
FIGURE5.Glucose uptake and AMPK signaling are required for efficient
CCL5-mediated chemotaxis.A,activated PB T cells were either left
untreated or pretreated with2-DG at the doses indicated for1h.A total of1?
105cells in100?l of chemotaxis buffer were then placed in the upper cham-
ber of Transwell https://www.doczj.com/doc/5610670117.html,L5-mediated chemotaxis was measured using
10n M CCL5.Data are presented as%migration,with the number of migrated
cells at10n M CCL5taken as100%.Data are representative of three independ-
ent experiments.B,activated PB T cells were pre-treated with either dimethyl
sulfoxide(DMSO;carrier)or different doses of compound C https://www.doczj.com/doc/5610670117.html,L5-
mediated chemotaxis was measured as described in A.Data are representa-
tive of three independent experiments.*,p?0.01.
CCL5Regulates Glucose Uptake and AMPK Signaling in T Cells
29414JOURNAL OF BIOLOGICAL CHEMISTRY VOLUME287?NUMBER35?AUGUST24,2012
taxing,which may require AMPK signaling to initiate ATP-generating processes.
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B/S测试与C/S测试之区别 我们在日常功能测试工作中，常常依据测试对象和测试目标的不同分为四个级别的测试，单元测试、集成测试、系统测试和验收测试，但是往往忽略了被测应用系统架构。在测试过程中针对不同的系统架构，测试的侧重点也不同。下面以B/S结构和C/S结构的特殊应用系统为例，分析在功能测试中的区别。 我们谈到的web系统是指以Brower/Server的访问方式为主，包含客户端浏览器、web应用服务器、数据库服务器的软件系统。一般的B/S结构，都是多层架构的，有界面层、业务逻辑层、数据层。由于这种结构不需要客户端的安装，客户端主要通过浏览器来访问，因此客户端测试的重点是：客户端操作系统（不同类型和版本）、客户端浏览器（不同类型和版本）以及客户端配置（cookie设置和分辨率设置）等测试。除客户端测试外，根据WEB系统常用技术还需要关注以下几个方面的测试： （1）链接测试 （2）表单测试 （3）脚本测试 （4）ActiveX控件测试 C/S（Client/Server）结构，即大家熟知的客户机和服务器结构。它是软件系统体系结构，通过它可以充分利用两端硬件环境的优势，将任务合理分配到Client端和Server端来实现，降低了系统的通讯开销。这种结构与B/S最显著的区别是需要安装客户端，通过客户端程序来访问应用系统，因此C/S客户端测试是重点，并且与B/S结构有所不同。 C/S客户端测试的重点有： （1）客户端安装测试 安装手册的评估 安装的自动化程度 安装选项和设置得测试 安装过程的中断测试 安装顺序测试 多环境安装测试
安装的正确性测试 修复安装测试 卸载安装测试 （2）客户端升级测试 与变更相关的测试 变更内容的测试 与变更相关的测试 （3）客户端与服务器链接测试 （4）服务器端数据验证 （5）客户端可维护性测试 以上内容总结了B/S与C/S系统测试的不同点，唯实践使理论之树常青，我们可以在实际工作中积累总结出更多的不同的测试关注点。 一、软件测试包括哪些内容? 以下是一些需要考虑的步骤： ü 1. 得到需求、功能设计、内部设计说书和其他必要的文档 ü 2. 得到预算和进度要求 ü 3. 确定与项目有关的人员和他们的责任、对报告的要求、所需的标准和过程(例如发行过程、变更过程、等等) ü 4. 确定应用软件的高风险范围，建立优先级、确定测试所涉及的范围和限制 ü 5. 确定测试的步骤和方法──部件、集成、功能、系统、负载、可用性等各种测试 ü 6. 确定对测试环境的要求(硬件、软件、通信等) ü7. 确定所需的测试用具(testware)，包括记录/回放工具、覆盖分析、测试跟踪、问题/错误跟踪、等等 ü8. 确定对测试的输入数据的要求 ü9. 分配任务和任务负责人，以及所需的劳动力 ü10.设立大致的时间表、期限、和里程碑 ü11.确定输入环境的类别、边界值分析、错误类别 ü12.准备测试计划文件和对计划进行必要的回顾 ü13.准备白盒测试案例 ü14.对测试案例进行必要的回顾/调查/计划 ü15.准备测试环境和测试用具，得到必需的用户手册/参考文件/结构指南/安装指南，
B/S与C/S的区别： C/S是Client/Server的缩写。服务器通常采用高性能的PC、工作站或小型机，并采用大型数据库系统，如Oracle、Sybase、Informix或 SQL Server。客户端需要安装专用的客户端软件。 B/Ｓ是Brower/Server的缩写，客户机上只要安装一个浏览器（Browser），如Netscape Navigator或Internet Explorer，服务器安装Oracle、Sybase、Informix或 SQL Server等数据库。用户界面完全通过WWW浏览器实现，主要事务逻辑在服务器端实现。浏览器通过Ｗeb Server 同数据库进行数据交互。 具体区别有： １．硬件环境不同: C/S 一般建立在专用的网络上，小范围里的网络环境，局域网之间再通过专门服务器提供连接和数据交换服务。 B/S 建立在广域网之上的，不必是专门的网络硬件环境，例与电话上网，租用设备。信息自己管理。有比C/S更强的适应范围，一般只要有操作系统和浏览器就行。 ２．对安全要求不同 C/S 一般面向相对固定的用户群，对信息安全的控制能力很强。一般高度机密的信息系统采用C/S 结构适宜。可以通过B/S发布部分可公开信息。 B/S 建立在广域网之上，对安全的控制能力相对弱，可能面向不可知的用户。 ３．对程序架构不同 C/S 程序可以更加注重流程，可以对权限多层次校验，对系统运行速度可以较少考虑。 B/S 对安全以及访问速度的多重的考虑，建立在需要更加优化的基础之上。比C/S有更高的要求 B/S结构的程序架构是发展的趋势，从MS的。Net系列的BizTalk 2000 Exchange 2000等，全面支持网络的构件搭建的系统。 SUN 和IBM推的JavaBean 构件技术等，使 B/S更加成熟。 ４．软件重用不同 C/S 程序可以不可避免的整体性考虑，构件的重用性不如在B/S要求下的构件的重用性好。 B/S 对的多重结构，要求构件相对独立的功能。能够相对较好的重用。就入买来的餐桌可以再利用，而不是做在墙上的石头桌子 ５．系统维护不同 C/S 程序由于整体性，必须整体考察，处理出现的问题以及系统升级。升级难。可能是再做一个全新的系统 B/S 构件组成，方面构件个别的更换，实现系统的无缝升级。系统维护开销减到最小。用户从网上自己下载安装就可以实现升级。 ６．处理问题不同 C/S 程序可以处理用户面固定，并且在相同区域，安全要求高需求，与操作系统相关。应该都是相同的系统 B/S 建立在广域网上，面向不同的用户群，分散地域，这是C/S无法作到的。与操作系统平台关系最小。
C/S 与B/S 区别： Client/Server是建立在局域网的基础上的.Browser/Server是建立在广域网的基础上的. 1．硬件环境不同: C/S 一般建立在专用的网络上, 小范围里的网络环境, 局域网之间再通过专门服务器提供连接和数据交换服务. B/S 建立在广域网之上的, 不必是专门的网络硬件环境,例与电话上网, 租用设备. 信息自己管理. 有比C/S更强的适应范围, 一般只要有操作系统和浏览器就行 2．对安全要求不同 C/S 一般面向相对固定的用户群, 对信息安全的控制能力很强. 一般高度机密的信息系统采用C/S 结构适宜. 可以通过B/S发布部分可公开信息. B/S 建立在广域网之上, 对安全的控制能力相对弱, 面向是不可知的用户群. 3．对程序架构不同 C/S 程序可以更加注重流程, 可以对权限多层次校验, 对系统运行速度可以较少考虑. B/S 对安全以及访问速度的多重的考虑, 建立在需要更加优化的基础之上. 比C/S有更高的要求B/S结构的程序架构是发展的趋势, 从MS的.Net系列的BizTalk 2000 Exchange 2000等, 全面支持网络的构件搭建的系统. SUN 和IBM推的JavaBean 构件技术等,使B/S更加成熟. 4．软件重用不同 C/S 程序可以不可避免的整体性考虑, 构件的重用性不如在B/S要求下的构件的重用性好. B/S 对的多重结构,要求构件相对独立的功能. 能够相对较好的重用.就入买来的餐桌可以再利用,而不是做在墙上的石头桌子 5．系统维护不同 系统维护是软件生存周期中,开销大, -------重要 C/S 程序由于整体性, 必须整体考察, 处理出现的问题以及系统升级. 升级难. 可能是再做一个全新的系统 B/S 构件组成,方面构件个别的更换,实现系统的无缝升级. 系统维护开销减到最小.用户从网上自己下载安装就可以实现升级. 6．处理问题不同 C/S 程序可以处理用户面固定, 并且在相同区域, 安全要求高需求, 与操作系统相关. 应该都是相同的系统 B/S 建立在广域网上, 面向不同的用户群, 分散地域, 这是C/S无法作到的. 与操作系统平台关系最小. 7．用户接口不同 C/S 多是建立的Window平台上,表现方法有限,对程序员普遍要求较高 B/S 建立在浏览器上, 有更加丰富和生动的表现方式与用户交流. 并且大部分难度减低,减低开发成本. 8．信息流不同 C/S 程序一般是典型的中央集权的机械式处理, 交互性相对低 B/S 信息流向可变化, B-B B-C B-G等信息、流向的变化, 更象交易中心
B/S与C/S区别 C/S结构，即Client/Server(客户机/服务器)结构，是大家熟知的软件系统体系结构，通过将任务合理分配到Client端和Server端，降低了系统的通讯开销，可以充分利用两端硬件环境的优势。早期的软 件系统多以此作为首选设计标准。 B/S结构，即Browser/Server(浏览器/服务器)结构，是随着Internet技术的兴起，对C/S 结构的一种变化或者改进的结构。在这种结构下，用户界面完全通过WWW浏览器实现，一部分事务逻辑在前端实现 ，但是主要事务逻辑在服务器端实现，形成所谓3-tier结构。B/S结构，主要是利用了不断成熟的WWW浏览器技术，结合浏览器的多种Script语言(VBScript、JavaScript…)和ActiveX 技术，用通用浏览器 就实现了原来需要复杂专用软件才能实现的强大功能，并节约了开发成本，是一种全新的软件系统构造技术。随着Windows 98/Windows 2000将浏览器技术植入操作系统内部，这种结构更成为当今应用软 件的首选体系结构。 C/S 与 B/S 区别： Client/Server是建立在局域网的基础上的.Browser/Server是建立在广域网的基础上的,但并不是说B/S结构不能在局域网上使用,如智赢IPOWER,在单机,局限网,广域网均能使用。1．硬件环境不同: C/S 一般建立在专用的网络上, 小范围里的网络环境, 局域网之间再通过专门服务器提供连接和数据交换服务. B/S 建立在广域网之上的, 不必是专门的网络硬件环境,例与电话上网, 租用设备. 信息自己管理. 有比C/S更强的适应范围, 一般只要有操作系统和浏览器就行 2．对安全要求不同 C/S 对服务端、客户端都安全都要考虑。 B/S 因没有客户端，所以只注重服务端安全即可。 3．对程序架构不同 C/S 程序可以更加注重流程, 可以对权限多层次校验, 对系统运行速度可以较少考虑. B/S 对安全以及访问速度的多重的考虑, 建立在需要更加优化的基础之上. 比C/S有更高的要求 B/S结构的程序架构是发展的趋势, 从MS的.Net系列的BizTalk 2000 Exchange 2000等, 全面支持网络的构 件搭建的系统. SUN 和IBM推的JavaBean 构件技术等,使 B/S更加成熟. 例如智赢IPOWER，采用AJAX和数据存储优化技术，相比一般B/S架构软件速度提高30%至99%。 4．软件重用不同 C/S 程序可以不可避免的整体性考虑, 构件的重用性不如在B/S要求下的构件的重用性好. B/S 对的多重结构,要求构件相对独立的功能. 能够相对较好的重用.就入买来的餐桌可以再利用,而不是做在墙上的石头桌子 5．系统维护不同
CS与BS的优劣比较 简介：CS即Client/Server(客户机/服务器)结构，C/S结构在技术上很成熟，它的主要特点是交互性强、具有安全的存取模式、网络通信量低、响应速度快、利于处理大量数据。但是该结构的程序是针对性开发，变更不够灵活，维护和管理的难度较大。通常只局限于小型局域网，不利于扩展。并且，由于该结构的每台客户机都需要安装相应的客户端程序，分布功能弱且兼容性差，不能实现快速部署安装和配置，因此缺少通用性，具有较大的局限性。要求具有一定专业水准的技术人员去完成。 BS即Browser/Server(浏览器/服务器)结构，BS是伴随着Internet技术的兴起，对C/S 架构的改进，为了区别于传统的C/S 模式，特意称为B/S模式。在这种结构下，通过W3C 浏览器来进入工作界面，极少部分事务逻辑在前端（Browser）实现，主要事务逻辑在服务器端（Web Server）实现，与数据库服务器形成三层（3-tier）结构。就是只安装维护一个服务器(Server)，而客户端采用浏览器(Browse)运行软件。B/S结构应用程序相对于传统的C/S结构应用程序是一个非常大的进步，是目前应用系统的发展方向。 B/S结构的主要特点是分布性强、维护方便、开发简单且共享性强、总体拥有成本低。但数据安全性问题、对服务器要求过高、数据传输速度慢、软件的个性化特点明显降低，这些缺点是有目共睹的，难以实现传统模式下的特殊功能要求。对大量的数据输入以及报表的应答等都需要通过浏览器与服务器进行交互，通信开销大，而且对于实现复杂的应用构造有较大的困难。例如通过浏览器进行大量的数据输入或进行报表的应答、专用性打印输出都比较困难和不便。此外，实现复杂的应用构造有较大的困难。 一、硬件环境 C/S客户端的计算机电脑配置要求较高。用户固定，并且处于相同区域，要求用兼容的操作系统。 B/S客户端的计算机电脑配置要求较低。要有操作系统和浏览器就行。与操作系统平台无关，但是需要兼容的浏览器。 三、系统的开发 C/S结构是建立在中间件产品基础之上的，要求应用开发者自己去处理事务管理、消息队列、数据的复制和同步、通信安全等系统级的问题。这对应用开发者提出了较高的要求，而且迫使应用开发者投入很多精力来解决应用程序以外的问题。 这使得应用程序的维护、移植和互操作变得复杂。如果客户端是在不同的操作系统上，C/S 结构的软件需要开发不同版本的客户端软件。但是，与B/S结构相比，C/S技术发展历史更为“悠久”。从技术成熟度及软件设计、开发人员的掌握水平来看，C/S技术应是更成熟、更可靠的。 四、软件安装 C/S每一个客户端都必须安装和配置软件,客户端不必安装，使用浏览器访问，易推广。 B/S最大的优点就是可以在任何地方进行操作而不用安装任何专门的软件。 五、软件升级和维护 C/S系统的各部分模块中有一部分改变，就要关联到其它模块的变动，重新编写程序，每个
C/S与B/S的区别与优缺点 C/S又称Client/Server或客户/服务器模式。服务器通常采用高性能的PC、工作站或小型机，并采用大型数据库系统，如Oracle、Sybase、Informix或 SQL Server。客户端需要安装专用的客户端软件。 B/Ｓ是Brower/Server的缩写，客户机上只要安装一个浏览器（Browser），如Netscape Navigator或Internet Explorer，服务器安装Oracle、Sybase、Informix或 SQL Server等数据库。浏览器通过Ｗeb Server 同数据库进行数据交互。 C/S的优点是能充分发挥客户端ＰＣ的处理能力，很多工作可以在客户端处理后再提交给服务器。对应的优点就是客户端响应速度快。缺点主要有以下几个： 只适用于局域网。而随着互联网的飞速发展，移动办公和分布式办公越来越普及，这需要我们的系统具有扩展性。这种方式远程访问需要专门的技术，同时要对系统进行专门的设计来处理分布式的数据。 客户端需要安装专用的客户端软件。首先涉及到安装的工作量，其次任何一台电脑出问题，如病毒、硬件损坏，都需要进行安装或维护。特别是有很多分部或专卖店的情况，不是工作量的问题，而是路程的问题。还有，系统软件升级时，每一台客户机需要重新安装，其维护和升级成本非常高。
对客户端的操作系统一般也会有限制。可能适应于Win98, 但不能用于win2000或Windows XP。或者不适用于微软新的操作系统等等，更不用说Linux、Ｕnix 等。 B/S最大的优点就是可以在任何地方进行操作而不用安装任何专门的软件。只要有一台能上网的电脑就能使用，客户端零维护。系统的扩展非常容易，只要能上网，再由系统管理员分配一个用户名和密码，就可以使用了。甚至可以在线申请，通过公司内部的安全认证（如ＣＡ证书）后，不需要人的参与，系统可以自动分配给用户一个账号进入系统。
SaaS、B/S、C/S三种不同模式软件的区别 作者：北森 Gartner调研结果显示，从2013年至2015年，美国企业的SaaS软件预算将增加78%。Saugatuck Technology预测到2016年，全球大于75%的新IT支出将用于云计算或混合云系统。到底何为SaaS软件，它与企业内部B/S架构部署的系统有什么不同，SaaS软件为什么那么有魅力？ 知识小普及 SaaS是Software-as-a-service（软件即服务），是一种随着互联网技术的发展和应用软件的成熟，提供基于互联网的全新的软件服务模式。SaaS提供商为企业搭建信息化所需要的所有网络基础设施及软件、硬件运作平台，并负责所有前期的实施、后期的维护等一系列服务，企业无需购买软硬件、建设机房、招聘IT人员，即可通过互联网使用信息系统。就像打开自来水龙头就能用水一样，企业根据实际需要，向SaaS提供商租赁软件服务。 SaaS软件是继C/S架构软件（Client/Server即客户/服务器，用户端需要安装专用的客户端软件，企业需要部署服务器），和传统B/S架构软件（Brower/Server即浏览器/服务器，用户端上只要安装一个浏览器，企业内部部署服务器）之后，为企业在线提供按需服务的软件应用服务模式（用户端也是采用浏览器，但企业无需部署服务器）。SaaS软件目前已成为软件产业的一个重要力量，是软件科技发展的趋势。 用户感知的SaaS 从最终用户感知的角度，SaaS模式软件和B/S架构软件没有差异，都是通过浏览器访问某个地址进行软件操作来完成业务流程化管理的过程。 但从企业感知和技术的角度，SaaS模式和B/S架构完全是两个维度的概念，前者是在B/S架构技术的基础上，在线为企业提供按需获取软件服务的全新商务服务模式。SaaS软件一定是B/S架构的，而B/S架构的软件却不一定是SaaS软件。 SAAS的真正魅力 1、省心省力省钱 企业无需在硬件方面和IT人员方面进行任何投资，即可获得软件服务。一个优秀的平台化SaaS软件还可以通过强大的配置能力，实现企业的个性化需求（比如，北森SaaS人才管理软件基于beisen cloud云平台搭建，支持企业灵活配置信息项、操作界面、流程、功能菜单、系统集成等）。 2、规避建设风险 ERP或eHR这样的企业应用软件，软件的部署和实施比软件本身的功能、性能更为重要，万一部署失败，那所有的投入几乎全部白费，这样的风险是每个企业用户都希望避免的。通常的ERP或eHR项目的部署周期至少需要半年以上甚至一两年或更久的时间，而SaaS 模式的软件项目部署最多也不会超过90天。 3、自动升级持续获得优秀服务 在传统安装软件模式下，企业想获取新特性一般要做升级实施，甚至要全部重新实施，这个过程往往需要支付昂贵的升级服务费。而SaaS软件却可以让企业永远随时获取到最新特性，而不用支付任何费用。企业甚至可以获得大数据挖掘所带来的价值和行业对标的服务价值。 4、数据安全更有保障 SaaS软件因为有厂商集中统一的存储、备份、防火墙和运营监控管理和专业强大的运
一、C/S结构的缺点 再提交给服务器。对应的优点就是客户端响应速度快。缺点主要有以下几个：而随着互联网的飞速发展，移动办公和分布式办公越来越普及，这需要我们的系统具有扩展性。这种方式远程访问需要专门的技术，同时要对系统进行专门的设计来处理分布式的数据。 客户端需要安装专用的客户端软件。首先涉及到安装的工作量，其次任何一台电脑出问题，如病毒、硬件损坏，都需要进行安装或维护。还有，系统软件升级时，每一台客户机需要重新安装，其维护和升级成本非常高。(大多数没法自动升级而需要人工升级）对客户端的操作系统一般也会有限制。可能适应于Windows 98，但不能用于Windows 2000或Windows XP。或者不适用于微软新的操作系统等等，更不用说Linux、Unix等。(中国绝大多数用户都使用Windows操作系统) （1）、应用服务器运行数据负荷较轻。最简单的C/S体系结构的数据库应用由两部 运行数据库服务器程序的机器，也称为应用服务器。一旦服务器程序被启动，就随时等待响应客户程序发来的请求；客户应用程序运行在用户自己的电脑上，对应于数据库服务器，可称为客户电脑，当需要对数据库中的数据进行任何操作时，客户程序就自动地寻找服务器程序，并向其发出请求，服务器程序根据预定的规则作出应答，送回结果，应用服务器运行数据负荷较轻。 （2）、数据的储存管理功能较为透明。在数据库应用中，数据的储存管理功能，是由服务器程序和客户应用程序分别独立进行的，前台应用可以违反的规则，并且通常把那些不同的（不管是已知还是未知的）运行数据，在服务器程序中不集中实现，例如访问者的权限，编号可以重复、必须有客户才能建立定单这样的规则。所有这些，对于工作在前台程序上的最终用户，是“透明”的，他们无须过问（通常也无法干涉）背后的过程，就可以完成自己的一切工作。在客户服务器架构的应用中，前台程序不是非常“瘦小”，麻烦的事情都交给了服务器和网络。在C/S体系的下，数据库不能真正成为公共、专业化的仓库，它受到独立的专门管理。
CS模式与BS模式的比较分析 2009-3-17 C/S模式主要由客户应用程序(Client)、服务器管理程序(Server)和中间件(middleware)三个部件组成。客户应用程序是系统中用户与数据进行交互的部件。服务器程序负责有效地管理系统资源，如管理一个信息数据库，其主要工作是当多个客户并发地请求服务器上的相同资源时，对这些资源进行最优化管理。中间件负责联结客户应用程序与服务器管理程序，协同完成一个作业，以满足用户查询管理数据的要求。 B/S模式是一种以Web技术为基础的新型的MIS系统平台模式。把传统C/S模式中的服务器部分分解为一个数据服务器与一个或多个应用服务器(Web服务器)，从而构成一个三层结构的客户服务器体系。 第一层客户机是用户与整个系统的接口。客户的应用程序精简到一个通用的浏览器软件，如Netscape Navigator，微软公司的IE等。浏览器将HTML代码转化成图文并茂的网页。网页还具备一定的交互功能，允许用户在网页提供的申请表上输入信息提交给后台，并提出处理请求。这个后台就是第二层的Web服务器。 第二层Web服务器将启动相应的进程来响应这一请求，并动态生成一串HTML代码，其中嵌入处理的结果，返回给客户机的浏览器。如果客户机提交的请求包括数据的存取，Web服务器还需与数据库服务器协同完成这一处理工作。 第三层数据库服务器的任务类似于C/S模式，负责协调不同的Web服务器发出的SQ 请求，管理数据库。 1. B/S模式的优势 首先它简化了客户端。它无需象C/S模式那样在不同的客户机上安装不同的客户应用程序，而只需安装通用的浏览器软件。这样不但可以节省客户机的硬盘空间与内存，而且使安装过程更加简便、网络结构更加灵活。假设一个企业的决策层要开一个讨论库存问题的会议，他们只需从会议室的计算机上直接通过浏览器查询数据，然后显示给大家看就可以了。甚至与会者还可以把笔记本电脑联上会议室的网络插口，自己来查询相关的数据。 其次，它简化了系统的开发和维护。系统的开发者无须再为不同级别的用户设计开发不同的客户应用程序了，只需把所有的功能都实现在Web服务器上，并就不同的功能为各个组别的用户设置权限就可以了。各个用户通过HTTP请求在权限范围内调用Web服务器上不同处理程序，从而完成对数据的查询或修改。现代企业面临着日新月异的竞争环境，对企业内部运作机制的更新与调整也变得逐渐频繁。相对于C/S，B/S的维护具有更大的灵活性。当形势变化时，它无须再为每一个现有的客户应用程序升级，而只需对Web服务器上的服务处理程序进行修订。这样不但可以提高公司的运作效率，还省去了维护时协调工作的不少麻烦。如果一个公司有上千台客户机，并且分布在不同的地点，那么便于维护将会显得更加重要。 再次，它使用户的操作变得更简单。对于C/S模式，客户应用程序有自己特定的规格，使用者需要接受专门培训。而采用B/S模式时，客户端只是一个简单易用的浏览器软件。无论是决策层还是操作层的人员都无需培训，就可以直接使用。B/S模式的这种特性，还使MIS系统维护的限制因素更少。 最后，B/S特别适用于网上信息发布，使得传统的MIS的功能有所扩展。这是C/S 所无法实现的。而这种新增的网上信息发布功能恰是现代企业所需的。这使得企业的大部分书面文件可以被电子文件取代，从而提高了企业的工作效率，使企业行政手续简化，节省人力物力。
定义： CS(Client/Server)，即客户端/服务器模式。是服务器连接各个使用客户端，客户端需要安装专用的客户端软件。CS架构的优点是能充分发挥客户端ＰＣ的处理能力，很多工作可以在客户端处理后再提交给服务器，客户端响应速度快。BS是Browser/Server的缩写，服务器连接各个浏览器，浏览器通过Web Server 同数据库进行数据交互，不需要安装专用的客户端软件。其本质是三层结构CS模式。 硬件要求： C/S又称Client/Server或客户/服务器模式。服务器通常采用高性能的PC、工作站或小型机，并采用大型数据库系统，如Oracle、Sybase、Informix或SQL Server。客户端需要安装专用的客户端软件。B/S是Brower/Server的缩写，客户机上只要安装一个浏览器（Browser），如Netscape Navigator或Internet Explorer，服务器安装Oracle、Sybase、Informix或SQL Server 等数据库。浏览器通过Ｗeb Server 同数据库进行数据交互。 架构的层次结构： B/S模式是一种三层结构的系统。第一层客户机是用户与整个系统的接口。客户的应用程序精简到一个通用的浏览器软件，如Netscape Navigator，微软公司的IE等。浏览器将HTML 代码转化成图文并茂的网页。网页还具备一定的交互功能，允许用户在网页提供的申请表上输入信息提交给后台，并提出处理请求。这个后台就是第二层的Web服务器。第二层Web 服务器将启动相应的进程来响应这一请求，并动态生成一串HTML代码，其中嵌入处理的结果，返回给客户机的浏览器。如果客户机提交的请求包括数据的存取，Web服务器还需与数据库服务器协同完成这一处理工作。第三层数据库服务器的任务类似于C/S模式，负责协调不同的Web服务器发出的SQ请求，管理数据库。 所谓"C/S"是指Client/Server（客户机/服务器）。C/S模式是一种两层结构的系统：第一层是在客户机系统上结合了表示与业务逻辑；第二层是通过网络结合了数据库服务器。 B/S架构软件的优势与劣势 （1）、维护和升级方式简单 目前，软件系统的改进和升级越来越频繁，B/S架构的产品明显体现着更为方便的特性。对一个稍微大一点单位来说，系统管理人员如果需要在几百甚至上千部电脑之间来回奔跑，效率和工作量是可想而知的，但B/S架构的软件只需要管理服务器就行了，所有的客户端只是浏览器，根本不需要做任何的维护。无论用户的规模有多大，有多少分支机构都不会增加任何维护升级的工作量，所有的操作只需要针对服务器进行；如果是异地，只需要把服务器连接专网即可，实现远程维护、升级和共享。所以客户机越来越“瘦”，而服务器越来越“胖”是将来信息化发展的主流方向。今后，软件升级和维护会越来越容易，而使用起来会越来越简单，这对用户人力、物力、时间、费用的节省是显而易见的，惊人的。因此，维护和升级革命的方式是“瘦”客户机，“胖”服务器。 （2）、成本降低，选择更多 大家都知道windows在桌面电脑上几乎一统天下，浏览器成为了标准配置，但在服务器操作系统上windows并不是处于绝对的统治地位。现在的趋势是凡使用B/S架构的应用管理软件，只需安装在Linux服务器上即可，而且安全性高。所以服务器操作系统的选择是很多的，不管选用那种操作系统都可以让大部分人使用windows作为桌面操作系统电脑不受影响，这就使的最流行免费的Linux操作系统快速发展起来，Linux除了操作系统是免费
C/S 在网络连接模式中,除对等网外,还有另一种形式的网络，即客户机/服务器网，Client/Server。在客户机/服务器网络中，服务器是网络的核心，而客户机是网络的基础，客户机依靠服务器获得所需要的网络资源，而服务器为客户机提供网络必须的资源。 这里客户和服务器都是指通信中所涉及的两个应用进程（软件）。使用计算机的人是计算机的“用户”（user）而不是“客户”（client）。但在许多国外文献中，也经常把运行客户程序的机器称为client（这种情况下也可把client译为“客户机”），把运行服务器程序的机器称为server。所以有时要根据上下文判断client与server是指软件还是硬件。 它是软件系统体系结构，通过它可以充分利用两端硬件环境的优势，将任务合理分配到Client端和Server端来实现，降低了系统的通讯开销。目前大多数应用软件系统都是Client/Server形式的两层结构，由于现在的软件应用系统正在向分布式的Web应用发展，Web和Client/Server应用都可以进行同样的业务处理，应用不同的模块共享逻辑组件；因此，内部的和外部的用户都可以访问新的和现有的应用系统，通过现有应用系统中的逻辑可以扩展出新的应用系统。这也就是目前应用系统的发展方向。 一、C/S结构的优点 C/S结构的优点是能充分发挥客户端PC的处理能力，很多工作可以在客户端处理后再提交给服务器。对应的优点就是客户端响应速度快。缺点主要有以下几个：而随着互联网的飞速发展，移动办公和分布式办公越来越普及，这需要我们的系统具有扩展性。这种方式远程访问需要专门的技术，同时要对系统进行专门的设计来处理分布式的数据。 客户端需要安装专用的客户端软件。首先涉及到安装的工作量，其次任何一台电脑出问题，如病毒、硬件损坏，都需要进行安装或维护。还有，系统软件升级时，每一台客户机需要重新安装，其维护和升级成本非常高。(知不知道可以自动升级？)对客户端的操作系统一般也会有限制。可能适应于Windows98，但不能用于Windows2000或Windows XP。或者不适用于微软新的操作系统等等，更不用说Linux、Unix等。(中国绝大多数用户都使用Windows操作系统) 二、C/S架构软件的优势与劣势 （1）、应用服务器运行数据负荷较轻。最简单的C/S体系结构的数据库应用由两部分组成，即客户应用程序和数据库服务器程序。二者可分别称为前台程序与后台程序。运行数据库服务器程序的机器，也称为应用服务器。一旦服务器程序被启动，就随时等待响应客户程序发来的请求；客户应用程序运行在用户自己的电脑上，对应于数据库服务器，可称为客户电脑，当需要对数据库中的数据进行任何操作时，客户程序就自动地寻找服务器程序，并向其发出请求，服务器程序根据预定的规则作出应答，
C/S Client/Server B/S Browser/Server 区别其实还是挺大的。 找篇文章给你看看，写的不错－－ 当今世界科学技术飞速发展，尤其以通信、计算机、网络为代表的互联网技术更是日新月异，令人眼花燎乱，目不睱接。由于计算机互联网在政治、经济、生活等各个领域的发展、运用以及网络的迅速普及和全社会对网络的依赖程度，计算机网络已经成为国家的经济基础和命脉，成为社会和经济发展强大动力，其地位越来越重要。但是，由于主流技术研发企业和用户对“B/S”和“C/S”技术谁优谁劣、谁代表技术潮流发展等等问题的争论不休，已经给检察机关使用“OA（办公）”和“案件管理”软件工作开展带来困惑，本文就此两项技术发展变化和应用前景做些探讨，供同行参考。 一、什么是C/S和B/S 要想对“C/S”和“B/S”技术发展变化有所了解，首先必须搞清楚三个问题。 第一、什么是C/S结构。 C/S （Client/Server）结构，即大家熟知的客户机和服务器结构。它是软件系统体系结构，通过它可以充分利用两端硬件环境的优势，将任务合理分配到Client端和Server端来实现，降低了系统的通讯开销。目前大多数应用软件系统都是Client/Server形式的两层结构，由于现在的软件应用系统正在向分布式的Web应用发展，Web和Client/Server 应用都可以进行同样的业务处理，应用不同的模块共享逻辑组件；因此，内部的和外部的用户都可以访问新的和现有的应用系统，通过现有应用系统中的逻辑可以扩展出新的应用系统。这也就是目前应用系统的发展方向。 传统的C／S体系结构虽然采用的是开放模式，但这只是系统开发一级的开放性，在特定的应用中无论是Client端还是Server端都还需要特定的软件支持。由于没能提供用户真正期望的开放环境，C/S结构的软件需要针对不同的操作系统系统开发不同版本的软件，加之产品的更新换代十分快，已经很难适应百台电脑以上局域网用户同时使用。而且代价高，效率低。 第二、什么是B/S结构。 B/S（Browser/Server）结构即浏览器和服务器结构。它是随着Internet技术的兴起，对C/S 结构的一种变化或者改进的结构。在这种结构下，用户工作界面是通过WWW浏览器来实现，极少部分事务逻辑在前端（Browser）实现，但是主要事务逻辑在服务器端（Server）实现，形成所谓三层3-tier结构。这样就大大简化了客户端电脑载荷，减轻了系统维护与升级的成本和工作量，降低了用户的总体成本（TCO）。 以目前的技术看，局域网建立B/S结构的网络应用，并通过Internet/Intranet模式下数据库应用，相对易于把握、成本也是较低的。它是一次性到位的开发，能实现不同的人员，从不同的地点，以不同的接入方式（比如LAN, W AN, Internet/Intranet等）访问和操作共同的数据
C/S和B/S结构的优缺点 B/S结构，即Browser/Server(浏览器/服务器)结构，是随着Internet技术的兴起，对C/S结构的一种变化或者改进的结构。在这种结构下，用户界面完全通过WWW浏览器实现，一部分事务逻辑在前端实现，但是主要事务逻辑在服务器端实现，形成所谓3-tier结构。B/S 结构，主要是利用了不断成熟的WWW浏览器技术，结合浏览器的多种Script语言(VBScript、JavaScript…)和ActiveX技术，用通用浏览器就实现了原来需要复杂专用软件才能实现的强大功能，并节约了开发成本，是一种全新的软件系统构造技术。随着Windows 98/Windows 2000将浏览器技术植入操作系统内部，这种结构更成为当今应用软件的首选体系结构。显然B/S结构应用程序相对于传统的C/S结构应用程序将是巨大的进步。 B/S结构采用星形拓扑结构建立企业内部通信网络或利用Internet虚拟专网（VPN）。前者的特点是安全、快捷、准确。后者则具有节省投资、跨地域广的优点。须视企业规模和地理分布确定。企业内部通过防火墙接入Internet，再整个网络采用TCP/IP协议。 C/S 与B/S 区别： Client/Server是建立在局域网的基础上的.Browser/Server是建立在广域网的基础上的. １．硬件环境不同: C/S 一般建立在专用的网络上, 小范围里的网络环境, 局域网之间再通过专门服务器提供连接和数据交换服务. B/S 建立在广域网之上的, 不必是专门的网络硬件环境,例与电话上网, 租用设备. 信息自己管理. 有比C/S更强的适应范围, 一般只要有操作系统和浏览器就行 ２．对安全要求不同 C/S 一般面向相对固定的用户群, 对信息安全的控制能力很强. 一般高度机密的信息系统采用C/S 结构适宜. 可以通过B/S发布部分可公开信息. B/S 建立在广域网之上, 对安全的控制能力相对弱, 面向是不可知的用户群. ３．对程序架构不同 C/S 程序可以更加注重流程, 可以对权限多层次校验, 对系统运行速度可以较少考虑. B/S 对安全以及访问速度的多重的考虑, 建立在需要更加优化的基础之上. 比C/S有更高的要求B/S结构的程序架构是发展的趋势, 从MS的.Net系列的BizTalk 2000 Exchange 2000等, 全面支持网络的构件搭建的系统. SUN 和IBM推的JavaBean 构件技术等,使B/S更加成熟. ４．软件重用不同 C/S 程序可以不可避免的整体性考虑, 构件的重用性不如在B/S要求下的构件的重用性好. B/S 对的多重结构,要求构件相对独立的功能. 能够相对较好的重用.就入买来的餐桌可以再利用,而不是做在墙上的石头桌子 ５．系统维护不同 系统维护是软件生存周期中,开销大, -------重要 C/S 程序由于整体性, 必须整体考察, 处理出现的问题以及系统升级. 升级难. 可能是再做一个全新的系统 B/S 构件组成,方面构件个别的更换,实现系统的无缝升级. 系统维护开销减到最小.用
C/S与B/S比较 C/S结构，即Client/Server(客户机/服务器)结构，是大家熟知的软件系统体系结构，通过将任务合理分配到Client端和Server端，降低了系统的通讯开销，可以充分利用两端硬件环境的优势。早期的软件系统多以此作为首选设计标准。。 B/S结构，即Browser/Server(浏览器/服务器)结构，是随着Internet技术的兴起，对C /S结构的一种变化或者改进的结构。在这种结构下，用户界面完全通过WWW浏览器实现，一部分事务逻辑在前端实现，但是主要事务逻辑在服务器端实现，形成所谓3-tier结构。B /S结构，主要是利用了不断成熟的WWW浏览器技术，结合浏览器的多种Script语言(V BScript、JavaScript…)和ActiveX技术，用通用浏览器就实现了原来需要复杂专用软件才能实现的强大功能，并节约了开发成本，是一种全新的软件系统构造技术。随着Windo ws 98/Windows 2000将浏览器技术植入操作系统内部，这种结构更成为当今应用软件的首选体系结构。 C/S 与B/S 区别： Client/Server是建立在局域网的基础上的.Browser/Server是建立在广域网的基础上的. 1．硬件环境不同: C/S 一般建立在专用的网络上, 小范围里的网络环境, 局域网之间再通过专门服务器提供连接和数据交换服务. B/S 建立在广域网之上的, 不必是专门的网络硬件环境,例与电话上网, 租用设备. 信息自己管理. 有比C/S更强的适应范围, 一般只要有操作系统和浏览器就行 2．对安全要求不同 C/S 一般面向相对固定的用户群, 对信息安全的控制能力很强. 一般高度机密的信息系统采用C/S 结构适宜. 可以通过B/S发布部分可公开信息. B/S 建立在广域网之上, 对安全的控制能力相对弱, 面向是不可知的用户群. 3．对程序架构不同 C/S 程序可以更加注重流程, 可以对权限多层次校验, 对系统运行速度可以较少考虑. B/S 对安全以及访问速度的多重的考虑, 建立在需要更加优化的基础之上. 比C/S有更高的要求B/S结构的程序架构是发展的趋势, 从MS的.Net系列的BizTalk 2000 Exchan ge 2000等, 全面支持网络的构件搭建的系统. SUN 和IBM推的JavaBean 构件技术等,使B/S更加成熟. 4．软件重用不同 C/S 程序可以不可避免的整体性考虑, 构件的重用性不如在B/S要求下的构件的重用性好. B/S 对的多重结构,要求构件相对独立的功能. 能够相对较好的重用.就入买来的餐桌可以 再利用,而不是做在墙上的石头桌子 5．系统维护不同 系统维护是软件生存周期中,开销大, -------重要 C/S 程序由于整体性, 必须整体考察, 处理出现的问题以及系统升级. 升级难. 可能是再 做一个全新的系统 B/S 构件组成,方面构件个别的更换,实现系统的无缝升级. 系统维护开销减到最小.用户从网上自己下载安装就可以实现升级. 6．处理问题不同
为了区别于传统的C/S模式，才特意将其称为B/S模式。认识到这些结构的特征，对于系统的选型而言是很关键的。 1、系统的性能 在系统的性能方面，B/S占有优势的是其异地浏览和信息采集的灵活性。任何时间、任何地点、任何系统，只要可以使用浏览器上网，就可以使用B/S系统的终端。 不过，采用B/S结构，客户端只能完成浏览、查询、数据输入等简单功能，绝大部分工作由服务器承担，这使得服务器的负担很重。采用C/S结构时，客户端和服务器端都能够处理任务，这虽然对客户机的要求较高，但因此可以减轻服务器的压力。而且，由于客户端使用浏览器，使得网上发布的信息必须是以HTML格式为主，其它格式文件多半是以附件的形式存放。而HTML格式文件（也就是Web页面）不便于编辑修改，给文件管理带来了许多不便。 2、系统的开发 C/S结构是建立在中间件产品基础之上的，要求应用开发者自己去处理事务管理、消息队列、数据的复制和同步、通信安全等系统级的问题。这对应用开发者提出了较高的要求，而且迫使应用开发者投入很多精力来解决应用程序以外的问题。这使得应用程序的维护、移植和互操作变得复杂。如果客户端是在不同的操作系统上，C/S结构的软件需要开发不同版本的客户端软件。但是，与B/S结构相比，C/S技术发展历史更为“悠久”。从技术成熟度及软件设计、开发人员的掌握水平来看，C/S技术应是更成熟、更可靠的。 3、系统的升级维护 C/S系统的各部分模块中有一部分改变，就要关联到其它模块的变动，使系统升级成本比较大。B/S与C/S处理模式相比，则大大简化了客户端，只要客户端机器能上网就可以。对于B/S而言，开发、维护等几乎所有工作也都集中在服务器端，当企业对网络应用进行升级时，只需更新服务器端的软件就可以，这减轻了异地用户系统维护与升级的成本。如果客户端的软件系统升级比较频繁，那么B/S架构的产品优势明显——所有的升级操作只需要针对服务器进行，这对那些点多面广的应用是很有价值的，例如一些招聘网站就需要采用B/S 模式，客户端分散，且应用简单，只需要进行简单的浏览和少量信息的录入。 4、C/S 模式的优点和缺点 ★C/S 模式的优点 ● 由于客户端实现与服务器的直接相连，没有中间环节，因此响应速度快。 ● 操作界面漂亮、形式多样，可以充分满足客户自身的个性化要求。 ● C/S结构的管理信息系统具有较强的事务处理能力，能实现复杂的业务流程。 ★C/S 模式的缺点 ● 需要专门的客户端安装程序，分布功能弱，针对点多面广且不具备网络条件的用户群体，不能够实现快速部署安装和配置。 ● 兼容性差，对于不同的开发工具，具有较大的局限性。若采用不同工具，需要重新改写程序。 ● 开发成本较高，需要具有一定专业水准的技术人员才能完成。 5、B/S模式的优点和缺点 ★B/S 模式的优点 ● 具有分布性特点，可以随时随地进行查询、浏览等业务处理。 ● 业务扩展简单方便，通过增加网页即可增加服务器功能。 ● 维护简单方便，只需要改变网页，即可实现所有用户的同步更新。 ● 开发简单，共享性强。