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.
旅途云（￥48 / 月），雅安高防4核4G、洛阳BGP 2核2G
公司成立于2007年，是国内领先的互联网业务平台服务提供商。公司专注为用户提供低价高性能云计算产品，致力于云计算应用的易用性开发，并引导云计算在国内普及。目前，旅途云公司研发以及运营云服务基础设施服务平台（IaaS），面向全球客户提供基于云计算的IT解决方案与客户服务，拥有丰富的国内BGP、双线高防、香港等优质的IDC资源。点击进入：旅途云官方网商家LOGO优惠方案：CPU内存硬盘带宽/流量/防御...
ATCLOUD.NET-OVH海外高防云主机，采用KVM架构，稳定安全且便宜好用，仅3刀起
官方网站：点击访问ATCLOUD.NET官网优惠码：目前提供Cloud VPS与Storage VPS两款产品的六折优惠活动(续费同价,截止至2021年5月31日)优惠码：UMMBPBR20Z活动方案：一、型号CPU内存磁盘流量优惠价格购买链接VPS-1GB0.5×2.6+GHz1GB20GB1TB$3立即购买VPS-2GB1×2.6+GHz2GB50GB2TB$6立即购买VPS-4GB2×2.6...
Digital-VM暑期全场六折优惠,8个机房
Digital-VM商家目前也在凑热闹的发布六月份的活动，他们家的机房蛮多的有提供8个数据中心，包括日本、洛杉矶、新加坡等。这次六月份的促销活动全场VPS主机六折优惠。Digital-VM商家还是有一点点特点的，有提供1Gbps和10Gbps带宽的VPS主机，如果有需要大带宽的VPS主机可以看看。第一、商家优惠码优惠码：June40全场主机六折优惠，不过仅可以月付、季付。第二、商家VPS主机套餐1...
sosos为你推荐
-
可以发外链的论坛有直接能带链接的论坛？行业关键词企业应如何做关键词排名google竞价排名谷歌竞价排名现在是显示在什么位置？yy频道中心YY怎么进入频道中心站长故事科学家的故事200字最新qq空间代码QQ空间代码渗透测试web渗透测试有前途吗自助建站自助建站可信吗？苹果5怎么越狱苹果5怎么越狱qq怎么发邮件怎么发送QQ邮件