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.
易探云月付18元起，香港/美国/深圳/北京VPS，CN2、BGP等多线路
易探云怎么样?易探云是国内一家云计算服务商家，致力香港服务器、国内外服务器租用及托管等互联网业务，目前主要地区为运作香港BGP、香港CN2、广东、北京、深圳等地区。易探云服务器均选择当下热门线路，比如CN2 GIA、BGP线路、CN2线路等，所有云主机支持月付，并且首月优惠，年付优惠，优惠后香港沙田云服务器/独立ip/香港CN2线路,每月仅18元,188元/年。点击进入：易探云官方网站地址1、香港...
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...
Friendhosting（月1.35欧元），不限流量，9机房可选
今天9月10日是教师节，我们今天有没有让孩子带礼物和花送给老师？我们这边不允许带礼物进学校，直接有校长在门口遇到有带礼物的直接拦截下来。今天有看到Friendhosting最近推出了教师节优惠，VPS全场45折，全球多机房可选，有需要的可以看看。Friendhosting是一家成立于2009年的保加利亚主机商，主要提供销售VPS和独立服务器出租业务，数据中心分布在：荷兰、保加利亚、立陶宛、捷克、乌...
sosos为你推荐
-
cornerradius如何给TextView加个圆角？易pc易PC价格多少天府热线天府热线怎么老是进不去？天天酷跑刷积分教程天天酷跑积分怎么获得 天天酷跑刷积分方法显卡温度多少正常显卡温度是多少才算正常的？ps抠图技巧ps中怎么抠图？网易公开课怎么下载如何将网易公开课下载到电脑上？ios7固件下载ios 7及以上固件请在设备上点信任在哪点数据库损坏数据库坏了,怎么修复?xp系统停止服务XP系统停止服务后电脑怎么办？