eralsosos
sosos 时间:2021-03-02 阅读:()
Autophagy6:8,1224-1226;November16,2010;2010LandesBioscienceAutophagicPunctum1224AutophagyVolume6Issue8Punctumto:RajawatYS,HiliotiZ,BossisI.
RetinoicAcidinducesautophagosomematurationthroughredistributionofthecation-independentmannose-6-phosphatereceptor.
AntioxidRedoxSignal2010;Inpress;PMID:20812861;DOI:10.
1089/ars.
2010.
3491.
Keywords:vitaminA,autophagosomematuration,amphisomes,autophagicefficiency,cation-independentmannose-6-phosphatereceptor,Beclin1,phospho-mTOR,phospho-Akt1Submitted:09/22/10Revised:09/28/10Accepted:09/29/10Previouslypublishedonline:www.
landesbioscience.
com/journals/autophagy/article/13793DOI:10.
4161/auto.
6.
8.
13793*Correspondenceto:IoannisBossis;Email:bossisi@umd.
eduAutophagyisanintracellularcata-bolicprocessthatrespondswithgreatsensitivitytonutrientavailability,implyingthatcertainmacro-ormicro-nutrientsareinvolved.
Wefoundthatretinoicacidpromotesautophagosomematurationthroughapathwayindepen-dentfromtheclassicnuclearretinoidreceptors.
Retinoicacidredistributesthecation-independentmannose-6-phop-shatereceptorfromthetrans-Golgiregiontomaturingautophagosomalstructuresinducingtheiracidification.
Manipulationoftheautophagicactivitybyretinoidscouldhaveenormoushealthimplications,sincetheyareessentialdietarycomponentsandfrequentlyusedpharmaceuticals.
VitaminAisanessentialdietarycom-ponentthatisinvolvedinseveralphysi-ologicalprocesses,suchasreproduction,embryonicdevelopment,tissueremodel-ing,visionandimmunefunction.
VitaminAdeficiencyhasbeenextensivelylinkedtoincreasedoxidativestress,inflammationandneurodegenerationandhistoricallyisconsideredasanutritionallyacquiredimmunodeficiencydisease.
Naturalandsyntheticretinoidsplayamajorroleinregulatingcellulargrowthanddifferentia-tion,andcaninduceapoptosisinawidevarietyofmalignantcells.
Themecha-nismhoweverbywhichretinoidsprotectagainstviralandbacterialinfectionsandsuppresstumorigenesisisstillunknown.
Regulationofautophagybymacro-nutrient(proteins,carbohydrates,lipids)availabilityiswellrecognized.
Ingen-eral,aminoaciddeprivationdirectlytrig-gerstheautophagicresponse,whereasAutophagyAtargetforretinoicacidsYogendraRajawat,ZoeHiliotiandIoannisBossis*DepartmentofVeterinaryMedicine;UniversityofMaryland;MDUSAcarbohydratesandlipidsaffectautophagyindirectlythroughtheinsulin/glucagonsignalingpathway.
WiththeexceptionofafewreportsonvitaminD3andsele-nium,theeffectofmicronutrientsandparticularlyvitaminAonautophagyhasnotbeenstudied.
Itisnoteworthy,how-ever,tomentionthateithervitaminAorautophagicdeficiencycanpotentiallyleadtosimilarpathophysiologicalconditions.
Toinvestigatetheroleofretinoicacidinautophagy,weinitiallysubjectedtran-sientlyandstablyCFP-LC3transfectedHeLacellstolowmicromolardosesofATRA(all-transretinoicacid)andnoticedadecreaseinthesteadystatelevelsofCFP-LC3-labeledautophagosomesbyconfocalmicroscopy.
However,wedidnotobserveanychangesintheratioofCFP-LC3-ItoCFP-LC3-IIbywesternblotting.
Bothprocedures,though,gavesimilarresultswhenthecellsweretreatedwithrapamycin,whichinducesautophagosomebiogenesis.
TodeterminewhetherATRAcouldaffectthesteadystatelevelsofautophagosomesbyinhibitingtheirfor-mation,weexaminedtheproteinlev-elsofBeclin1,phosphorylatedmTORandphosphorylatedAkt1underretinoidstimulation.
Ourstudiessuggestedthatretinoidsdonotaffecttheearlystagesofautophagosomeformation.
However,itiswellacceptedinthefieldthat,uponbio-genesis,autophagosomesprogressthroughaseriesofmaturationeventsbeforefusionwithlysosomesandformationofautoly-sosomes.
Therefore,changesinthepHoftheautophagosomallumenorfusionwiththeacidiclysosomescouldinducefluorescentquenchingofCFP/GFP/EYFPfusionproteins.
Indeed,treatmentofwww.
landesbioscience.
comAutophagy1225AutophagicPunctumAutophagicPunctum(acidified)autophagosomesdonotexist.
Inaddition,themechanismbywhichautophagosomesbecomeacidifiedisnotfullyunderstood;however,fusionwithlateacidicendosomeshasbeensuggested.
Inoureffortstodeterminethemech-anismofretinoicacid-inducedauto-phagosomematuration,weperformedseveralstudiesusingspecificantagonistsandagonistsoftheclassicretinoicacidreceptors(RARsandRXRs).
Ourobser-vationsstronglysuggestedthattheclas-sicRARsandRXRsreceptorsdonotmediatetheeffectsofretinoidsonauto-phagosomematuration.
Recentevidence,mCherry-LC3transfectedcells(mCherryisacidresistant)withATRAdidnotresultinsignificantchangeinthenumberofautophagosomes/auto-lysosomes.
Tofurtherverifythisobservation,wesub-jectedGFP-mCherry-LC3(pHsensitivereporter)transfectedcellstoATRAandobservedasignificantreductionintheratioofyellow/redpuncta.
Theseobser-vationssuggestedthatATRAeitherpro-motesautophagosome/lysosomefusionorinducesautophagosomeacidification(e.
g.
,bythegenerationofamphisomes).
ItisworthmentioningthatreliablemarkerstodistinguishbetweenearlyandmaturingFigure1.
Inductionofautophagosome(AP)maturationbyretinoidsthroughredistributionofthecation-independentmannose-6phosphaterecep-tor(CIMPR).
InitialformationofAPstakesplacebyengulfingofcargowithinthephagophore(PG).
ThePGelongatesandclosestoformavesiclethroughaprocessmediatedbytheLC3conjugationsystem.
APsthenundergomaturationbeforefusionwithlysosomesandformationofautolyso-somes.
Thismaturationprocesspotentiallyreliesonacquisitionofthevacuolar-typeprotonATPasepumpthatmediatesacidification.
Thisacidifica-tioncanbeaccomplishedbyeitherfusionofAPswithasubsetoflateendosomesandmultivesicularbodiesenrichedinprotonpumpstoformamphisomes,orbydirecttranslocationoftheprotonpumpfromtheTGNtoAPs.
TranslocationoftheprotonpumpandotherhydrolyticenzymesreliesonCIMPR.
BindingofretinoicacidtoCIMPR-enzymecomplexesintheTGNinducestheirtranslocationtolateendosomes(A)orAPs(B)andpromotesacidification.
thoughhassuggestedthatotherretinoidresponsepathwaysthatareindependentofthenuclearreceptorsmayexist.
Althoughthebiologicalsignificanceofretinoicacidbindingtoalternativeintracellularsitesisnotunderstood,itwasofinteresttousthatphotoaffinitylabelingstudieshaveshowndirectbindingofATRAtothecat-ion-independentmannose-6-phosphate/IGFIIreceptor(CIMPR)withhighaffin-ity.
CIMPRisaubiquitouslyandconstitu-tivelyexpressedlargeglycoprotein(~300kDa)thatplaysafundamentalroleinendocytosisanddegradationofextracel-lularligands(IGF-II,uPAR),andsorting1226AutophagyVolume6Issue8andtransportingmannose-6-phosphatebearingglycoproteins(suchashydrolases)fromthetrans-Golginetwork(TGN)toendosomes.
Toinvestigatepotentialeffectsofretinoidsontheintracellulartraffick-ingofCIMPR,wepreparedmGFP-andmRFP-taggedfull-lengthCIMPRcon-structs.
Underbasalconditions,thefluo-rescentCIMPRfusionproteinsaremostlylocalizedintheperinuclearTGN,somevesicularcompartmentsandtheplasmamembrane.
TreatmentwithretinoidsinparallelexperimentsinducessignificantredistributionofCIMPRfusionproteinstoperipheralvesicularstructuresthatarenotlabeledwithCFP-LC3orLAMP-1-RFP(lysosomalmarker)butarepositiveformCherry-LC3.
ThesedatasuggestedthatretinoicacidinducesredistributionofCIMPRintoacidifiedautophagosomes(oramphisomes).
TofurtherunderstandtheroleofCIMPRinautophagosomematuration,weutilizedsiRNA-mediatedsilencingofendogenousCIMPRlevels.
KnockdownofCIMPRleadstoremarkableaccu-mulationofnonacidifiedimmatureautophagosomesandRab9-labeledlateendosomes,buthasnoeffectontheabundanceoflysosomes.
Inadditionthiseffectcannotbereversedbyretinoicacidtreatment,furtherdemonstratingthattheeffectsofthesecompoundsonautophagosomematurationaremedi-atedthroughCIMPR.
AccumulationofearlynonacidifiedautophagosomesintheabsenceofCIMPRindicatestheimportanceofthisglycoproteininauto-phagosomematuration,butalsosuggeststhatautophagosomeacidificationmightberequiredbeforefusionwithlyso-somes.
ItcanbespeculatedthatCIMPRisrequiredforacidificationofasubsetoflateendosomes,whichinturnmedi-ateautophagosomematurationthroughfusion.
Alternatively,directtranslocationofCIMPRtoautophagosomesmaybemediatingtheiracidification(Fig.
1).
Pharmacologicalmodulationofdis-ruptedautophagicactivityhasbeensug-gestedasastrategyfortherapieswithinawidespectrumofpathologicalsituationsincludingcancer,neurologicaldiseases,prematureagingandinfectiousdiseases.
Althoughretinoidsareamultitargetingclassofcompoundsthatcanmodulateseveralphysiologicalandcellularpro-cesses,weidentifiedanovelmechanisminvolvingtheCIMPRbywhichretinoidsaffectautophagy.
Thisfindingcanlaythefoundationforthedevelopmentofnewandspecificretinoidanaloguesthatcouldenhanceorreduceautophagicactivity.
RetinoicAcidinducesautophagosomematurationthroughredistributionofthecation-independentmannose-6-phosphatereceptor.
AntioxidRedoxSignal2010;Inpress;PMID:20812861;DOI:10.
1089/ars.
2010.
3491.
Keywords:vitaminA,autophagosomematuration,amphisomes,autophagicefficiency,cation-independentmannose-6-phosphatereceptor,Beclin1,phospho-mTOR,phospho-Akt1Submitted:09/22/10Revised:09/28/10Accepted:09/29/10Previouslypublishedonline:www.
landesbioscience.
com/journals/autophagy/article/13793DOI:10.
4161/auto.
6.
8.
13793*Correspondenceto:IoannisBossis;Email:bossisi@umd.
eduAutophagyisanintracellularcata-bolicprocessthatrespondswithgreatsensitivitytonutrientavailability,implyingthatcertainmacro-ormicro-nutrientsareinvolved.
Wefoundthatretinoicacidpromotesautophagosomematurationthroughapathwayindepen-dentfromtheclassicnuclearretinoidreceptors.
Retinoicacidredistributesthecation-independentmannose-6-phop-shatereceptorfromthetrans-Golgiregiontomaturingautophagosomalstructuresinducingtheiracidification.
Manipulationoftheautophagicactivitybyretinoidscouldhaveenormoushealthimplications,sincetheyareessentialdietarycomponentsandfrequentlyusedpharmaceuticals.
VitaminAisanessentialdietarycom-ponentthatisinvolvedinseveralphysi-ologicalprocesses,suchasreproduction,embryonicdevelopment,tissueremodel-ing,visionandimmunefunction.
VitaminAdeficiencyhasbeenextensivelylinkedtoincreasedoxidativestress,inflammationandneurodegenerationandhistoricallyisconsideredasanutritionallyacquiredimmunodeficiencydisease.
Naturalandsyntheticretinoidsplayamajorroleinregulatingcellulargrowthanddifferentia-tion,andcaninduceapoptosisinawidevarietyofmalignantcells.
Themecha-nismhoweverbywhichretinoidsprotectagainstviralandbacterialinfectionsandsuppresstumorigenesisisstillunknown.
Regulationofautophagybymacro-nutrient(proteins,carbohydrates,lipids)availabilityiswellrecognized.
Ingen-eral,aminoaciddeprivationdirectlytrig-gerstheautophagicresponse,whereasAutophagyAtargetforretinoicacidsYogendraRajawat,ZoeHiliotiandIoannisBossis*DepartmentofVeterinaryMedicine;UniversityofMaryland;MDUSAcarbohydratesandlipidsaffectautophagyindirectlythroughtheinsulin/glucagonsignalingpathway.
WiththeexceptionofafewreportsonvitaminD3andsele-nium,theeffectofmicronutrientsandparticularlyvitaminAonautophagyhasnotbeenstudied.
Itisnoteworthy,how-ever,tomentionthateithervitaminAorautophagicdeficiencycanpotentiallyleadtosimilarpathophysiologicalconditions.
Toinvestigatetheroleofretinoicacidinautophagy,weinitiallysubjectedtran-sientlyandstablyCFP-LC3transfectedHeLacellstolowmicromolardosesofATRA(all-transretinoicacid)andnoticedadecreaseinthesteadystatelevelsofCFP-LC3-labeledautophagosomesbyconfocalmicroscopy.
However,wedidnotobserveanychangesintheratioofCFP-LC3-ItoCFP-LC3-IIbywesternblotting.
Bothprocedures,though,gavesimilarresultswhenthecellsweretreatedwithrapamycin,whichinducesautophagosomebiogenesis.
TodeterminewhetherATRAcouldaffectthesteadystatelevelsofautophagosomesbyinhibitingtheirfor-mation,weexaminedtheproteinlev-elsofBeclin1,phosphorylatedmTORandphosphorylatedAkt1underretinoidstimulation.
Ourstudiessuggestedthatretinoidsdonotaffecttheearlystagesofautophagosomeformation.
However,itiswellacceptedinthefieldthat,uponbio-genesis,autophagosomesprogressthroughaseriesofmaturationeventsbeforefusionwithlysosomesandformationofautoly-sosomes.
Therefore,changesinthepHoftheautophagosomallumenorfusionwiththeacidiclysosomescouldinducefluorescentquenchingofCFP/GFP/EYFPfusionproteins.
Indeed,treatmentofwww.
landesbioscience.
comAutophagy1225AutophagicPunctumAutophagicPunctum(acidified)autophagosomesdonotexist.
Inaddition,themechanismbywhichautophagosomesbecomeacidifiedisnotfullyunderstood;however,fusionwithlateacidicendosomeshasbeensuggested.
Inoureffortstodeterminethemech-anismofretinoicacid-inducedauto-phagosomematuration,weperformedseveralstudiesusingspecificantagonistsandagonistsoftheclassicretinoicacidreceptors(RARsandRXRs).
Ourobser-vationsstronglysuggestedthattheclas-sicRARsandRXRsreceptorsdonotmediatetheeffectsofretinoidsonauto-phagosomematuration.
Recentevidence,mCherry-LC3transfectedcells(mCherryisacidresistant)withATRAdidnotresultinsignificantchangeinthenumberofautophagosomes/auto-lysosomes.
Tofurtherverifythisobservation,wesub-jectedGFP-mCherry-LC3(pHsensitivereporter)transfectedcellstoATRAandobservedasignificantreductionintheratioofyellow/redpuncta.
Theseobser-vationssuggestedthatATRAeitherpro-motesautophagosome/lysosomefusionorinducesautophagosomeacidification(e.
g.
,bythegenerationofamphisomes).
ItisworthmentioningthatreliablemarkerstodistinguishbetweenearlyandmaturingFigure1.
Inductionofautophagosome(AP)maturationbyretinoidsthroughredistributionofthecation-independentmannose-6phosphaterecep-tor(CIMPR).
InitialformationofAPstakesplacebyengulfingofcargowithinthephagophore(PG).
ThePGelongatesandclosestoformavesiclethroughaprocessmediatedbytheLC3conjugationsystem.
APsthenundergomaturationbeforefusionwithlysosomesandformationofautolyso-somes.
Thismaturationprocesspotentiallyreliesonacquisitionofthevacuolar-typeprotonATPasepumpthatmediatesacidification.
Thisacidifica-tioncanbeaccomplishedbyeitherfusionofAPswithasubsetoflateendosomesandmultivesicularbodiesenrichedinprotonpumpstoformamphisomes,orbydirecttranslocationoftheprotonpumpfromtheTGNtoAPs.
TranslocationoftheprotonpumpandotherhydrolyticenzymesreliesonCIMPR.
BindingofretinoicacidtoCIMPR-enzymecomplexesintheTGNinducestheirtranslocationtolateendosomes(A)orAPs(B)andpromotesacidification.
thoughhassuggestedthatotherretinoidresponsepathwaysthatareindependentofthenuclearreceptorsmayexist.
Althoughthebiologicalsignificanceofretinoicacidbindingtoalternativeintracellularsitesisnotunderstood,itwasofinteresttousthatphotoaffinitylabelingstudieshaveshowndirectbindingofATRAtothecat-ion-independentmannose-6-phosphate/IGFIIreceptor(CIMPR)withhighaffin-ity.
CIMPRisaubiquitouslyandconstitu-tivelyexpressedlargeglycoprotein(~300kDa)thatplaysafundamentalroleinendocytosisanddegradationofextracel-lularligands(IGF-II,uPAR),andsorting1226AutophagyVolume6Issue8andtransportingmannose-6-phosphatebearingglycoproteins(suchashydrolases)fromthetrans-Golginetwork(TGN)toendosomes.
Toinvestigatepotentialeffectsofretinoidsontheintracellulartraffick-ingofCIMPR,wepreparedmGFP-andmRFP-taggedfull-lengthCIMPRcon-structs.
Underbasalconditions,thefluo-rescentCIMPRfusionproteinsaremostlylocalizedintheperinuclearTGN,somevesicularcompartmentsandtheplasmamembrane.
TreatmentwithretinoidsinparallelexperimentsinducessignificantredistributionofCIMPRfusionproteinstoperipheralvesicularstructuresthatarenotlabeledwithCFP-LC3orLAMP-1-RFP(lysosomalmarker)butarepositiveformCherry-LC3.
ThesedatasuggestedthatretinoicacidinducesredistributionofCIMPRintoacidifiedautophagosomes(oramphisomes).
TofurtherunderstandtheroleofCIMPRinautophagosomematuration,weutilizedsiRNA-mediatedsilencingofendogenousCIMPRlevels.
KnockdownofCIMPRleadstoremarkableaccu-mulationofnonacidifiedimmatureautophagosomesandRab9-labeledlateendosomes,buthasnoeffectontheabundanceoflysosomes.
Inadditionthiseffectcannotbereversedbyretinoicacidtreatment,furtherdemonstratingthattheeffectsofthesecompoundsonautophagosomematurationaremedi-atedthroughCIMPR.
AccumulationofearlynonacidifiedautophagosomesintheabsenceofCIMPRindicatestheimportanceofthisglycoproteininauto-phagosomematuration,butalsosuggeststhatautophagosomeacidificationmightberequiredbeforefusionwithlyso-somes.
ItcanbespeculatedthatCIMPRisrequiredforacidificationofasubsetoflateendosomes,whichinturnmedi-ateautophagosomematurationthroughfusion.
Alternatively,directtranslocationofCIMPRtoautophagosomesmaybemediatingtheiracidification(Fig.
1).
Pharmacologicalmodulationofdis-ruptedautophagicactivityhasbeensug-gestedasastrategyfortherapieswithinawidespectrumofpathologicalsituationsincludingcancer,neurologicaldiseases,prematureagingandinfectiousdiseases.
Althoughretinoidsareamultitargetingclassofcompoundsthatcanmodulateseveralphysiologicalandcellularpro-cesses,weidentifiedanovelmechanisminvolvingtheCIMPRbywhichretinoidsaffectautophagy.
Thisfindingcanlaythefoundationforthedevelopmentofnewandspecificretinoidanaloguesthatcouldenhanceorreduceautophagicactivity.
Vultr VPS韩国首尔机房速度和综合性能参数测试
Vultr 商家有新增韩国首尔机房，这个是继日本、新加坡之后的第三个亚洲机房。不过可以大概率知道肯定不是直连中国机房的，因为早期的日本机房有过直连后来取消的。今天准备体验看看VULTR VPS主机商的韩国首尔机房的云服务器的速度和性能。1、全球节点PING速度测试这里先通过PING测试工具看看全球几十个节点的PING速度。看到好像移动速度还不错。2、路由去程测试测试看看VULTR韩国首尔机房的节点...
raksmart：全新cloud云服务器系列测评，告诉你raksmart新产品效果好不好
2021年6月底，raksmart开发出来的新产品“cloud-云服务器”正式上线对外售卖，当前只有美国硅谷机房（或许以后会有其他数据中心加入）可供选择。或许你会问raksmart云服务器怎么样啊、raksm云服务器好不好、网络速度快不好之类的废话（不实测的话），本着主机测评趟雷、大家受益的原则，先开一个给大家测评一下！官方网站：https://www.raksmart.com云服务器的说明：底层...
云俄罗斯VPSJusthost俄罗斯VPS云服务器justg：JustHost、RuVDS、JustG等俄罗斯vps主机
俄罗斯vps云服务器商家推荐!俄罗斯VPS，也叫毛子主机(毛子vps)，因为俄罗斯离中国大陆比较近，所以俄罗斯VPS的延迟会比较低，国内用户也不少，例如新西伯利亚机房和莫斯科机房都是比较热门的俄罗斯机房。这里为大家整理推荐一些好用的俄罗斯VPS云服务器，这里主要推荐这三家：justhost、ruvds、justg等俄罗斯vps主机，方便大家对比购买适合自己的俄罗斯VPS。一、俄罗斯VPS介绍俄罗斯...
sosos为你推荐
-
自助建站自助建站可信吗？网站运营网站运营的工作做什么显卡温度多少正常显卡温度多少正常保护气球抖音里面看的，这是什么游戏安装迅雷看看播放器怎样安装迅雷看看播放器免费免费建站最好的免费建站ejb开发EJB是什么?二层交换机二层交换机是什么意思，三层呢虚拟专用网虚拟专用网 有什么用处?如何快速收录如何让百度快速收录