Upregulation of RIN3 induces endosomal dysfunction in Alzheimer’s disease  

作　　者：Ruinan Shen Xiaobei Zhao Lu He Yongbo Ding Wei Xu Suzhen Lin Savannah Fang Wanlin Yang Kijung Sung Brian Spencer Robert A.Rissman Ming Lei Jianqing Ding Chengbiao Wu 

机构地区：[1]Institute of Neurology,Ruijing Hospital,Shanghai JiaoTong University School of Medicine,197 Ruijin Er Rd.,Shanghai,200025,China [2]Department of Neurosciences,University of California San Diego School of Medicine,Room 312 MC-0624,9500 Gilman Drive,La Jolla,CA,92093-0624,USA [3]Shanghai Institute of Precision Medicine,Shanghai,200125,China [4]Department of Neurology,Zhuijiang Hospital,Southern Medical University,Guangzhou,China [5]San Diego VA Health System,San Diego,CA,USA

出　　处：《Translational Neurodegeneration》2020年第2期290-308,共19页转化神经变性病（英文）

基　　金：The project was financially supported by the National Natural Science Foundation of China[#81630029 and#81871005 for JD];the National Key R&D Program of China[#2016YFC13060000 for JD].UCSD ADRC P50 Pilot Grant(Wu).

摘　　要：Background In Alzheimer’s Disease(AD),about one-third of the risk genes identified by GWAS encode proteins that function predominantly in the endocytic pathways.Among them,the Ras and Rab Interactor 3(RIN3)is a guanine nucleotide exchange factor(GEF)for the Rab5 small GTPase family and has been implicated to be a risk factor for both late onset AD(LOAD)and sporadic early onset AD(sEOAD).However,how RIN3 is linked to AD pathogenesis is currently undefined.Methods Quantitative PCR and immunoblotting were used to measure the RIN3 expression level in mouse brain tissues and cultured basal forebrain cholinergic neuron(BFCNs).Immunostaining was used to define subcellular localization of RIN3 and to visualize endosomal changes in cultured primary BFCNs and PC12 cells.Recombinant flag-tagged RIN3 protein was purified from HEK293T cells and was used to define RIN3-interactomes by mass spectrometry.RIN3-interacting partners were validated by co-immunoprecipitation,immunofluorescence and yeast two hybrid assays.Live imaging of primary neurons was used to examine axonal transport of amyloid precursor protein(APP)andβ-secretase 1(BACE1).Immunoblotting was used to detect protein expression,processing of APP and phosphorylated forms of Tau.Results We have shown that RIN3 mRNA level was significantly increased in the hippocampus and cortex of APP/PS1 mouse brain.Basal forebrain cholinergic neurons(BFCNs)cultured from E18 APP/PS1 mouse embryos also showed increased RIN3 expression accompanied by early endosome enlargement.In addition,via its proline rich domain,RIN3 recruited BIN1(bridging integrator 1)and CD2AP(CD2 associated protein),two other AD risk factors,to early endosomes.Interestingly,overexpression of RIN3 or CD2AP promoted APP cleavage to increase its carboxyl terminal fragments(CTFs)in PC12 cells.Upregulation of RIN3 or the neuronal isoform of BIN1 increased phosphorylated Tau level.Therefore,upregulation of RIN3 expression promoted accumulation of APP CTFs and increased phosphorylated Tau.These effects by RIN3 was

关 键 词：Alzheimer's disease(AD) AD risk factors ENDOSOMES TRAFFICKING RIN3 BIN1 CD2AP Tau 

分 类 号：R749.16[医药卫生—神经病学与精神病学]