N^(6)-methyladenosine(m^(6)A)modification,which is achieved by the METTL3/METTL14/WTAP methyltransferase complex,is the most abundant internal mRNA modification.Although recent evidence indicates that m^(6)A can regul...N^(6)-methyladenosine(m^(6)A)modification,which is achieved by the METTL3/METTL14/WTAP methyltransferase complex,is the most abundant internal mRNA modification.Although recent evidence indicates that m^(6)A can regulate neurodevelopment as well as synaptic function,the roles of m^(6)A modification in the cerebellum and related synaptic connections are not well established.Here,we report that Purkinje cell(PC)-specific WTAP knockout mice display early-onset ataxia concomitant with cerebellar atrophy due to extensive PC degeneration and apoptotic cell death.Loss of Wtap also causes the aberrant degradation of multiple PC synapses.WTAP depletion leads to decreased expression levels of METTL3/14 and reduced m^(6)A methylation in PCs.Moreover,the expression of GFAP and NF-L in the degenerating cerebellum is increased,suggesting severe neuronal injuries.In conclusion,this study demonstrates the critical role of WTAP-mediated m^(6)A modification in cerebellar PCs,thus providing unique insights related to neurodegenerative disorders.展开更多
Inherited retinal dystrophies (IRDs) are major causes of visual impairment and irreversible blindness worldwide, while the precise molecular and genetic mechanisms are still elusive. N6-methyladenosine (m^(6)A) modifi...Inherited retinal dystrophies (IRDs) are major causes of visual impairment and irreversible blindness worldwide, while the precise molecular and genetic mechanisms are still elusive. N6-methyladenosine (m^(6)A) modification is the most prevalent internal modification in eukaryotic mRNA. YTH domain containing 2 (YTHDC2), an m^(6)A reader protein, has recently been identified as a key player in germline development and human cancer. However, its contribution to retinal function remains unknown. Here, we explore the role of YTHDC2 in the visual function of retinal rod photoreceptors by generating rod-specific Ythdc2 knockout mice. Results show that Ythdc2 deficiency in rods causes diminished scotopic ERG responses and progressive retinal degeneration. Multi-omics analysis further identifies Ppef2 and Pde6b as the potential targets of YTHDC2 in the retina. Specifically, via its YTH domain, YTHDC2 recognizes and binds m^(6)A-modified Ppef2 mRNA at the coding sequence and Pde6b mRNA at the 5′-UTR, resulting in enhanced translation efficiency without affecting mRNA levels. Compromised translation efficiency of Ppef2 and Pde6b after YTHDC2 depletion ultimately leads to decreased protein levels in the retina, impaired retinal function, and progressive rod death. Collectively, our finding highlights the importance of YTHDC2 in visual function and photoreceptor survival, which provides an unreported elucidation of IRD pathogenesis via epitranscriptomics.展开更多
The endoplasmic reticulum(ER) membrane protein complex(EMC) regulates the synthesis and quality control of membrane proteins with multiple transmembrane domains. One of the membrane spanning subunits, EMC3, is a core ...The endoplasmic reticulum(ER) membrane protein complex(EMC) regulates the synthesis and quality control of membrane proteins with multiple transmembrane domains. One of the membrane spanning subunits, EMC3, is a core member of the EMC complex that provides essential hydrophilic vestibule for substrate insertion. Here, we show that the EMC subunit Emc3 plays critical roles in the retinal vascular angiogenesis by regulating Norrin/Wnt signaling. Postnatal endothelial cell(EC)-specific deletion of Emc3 led to retarded retinal vascular development with a hyperpruned vascular network, the appearance of bluntended, aneurysm-like tip endothelial cells(ECs) with reduced numbers of filopodia and leakage of erythrocytes at the vascular front. Diminished tube formation and cell proliferation were also observed in EMC3 depleted human retinal endothelial cells(HRECs). We then discovered a critical role for EMC3 in expression of FZD4 receptor of β-catenin signaling using RNA sequencing, real-time quantitative PCR(RT-q PCR) and luciferase reporter assay. Moreover, augmentation of Wnt activity via lithium chloride(Li Cl) treatment remarkably enhanced β-catenin signaling and cell proliferation of HRECs. Additionally, Li Cl partially reversed the angiogenesis defects in Emc3-c KO mice. Our data reveal that Emc3 plays essential roles in angiogenesis through direct control of FZD4 expression and Norrin/β-catenin signaling.展开更多
Endoplasmic reticulum(ER)membrane protein complex(EMC)is required for the co-translational insertion of newly synthesized multi-transmembrane proteins.Compromised EMC function in different cell types has been implicat...Endoplasmic reticulum(ER)membrane protein complex(EMC)is required for the co-translational insertion of newly synthesized multi-transmembrane proteins.Compromised EMC function in different cell types has been implicated in multiple diseases.Using inducible genetic mouse models,we revealed defects in retinal vascularization upon endothelial cell(EC)specific deletion of Emc1,the largest subunit of EMC.Loss of Emc1 in ECs led to reduced vascular progression and vascular density,diminished tip cell sprouts,and vascular leakage.We then performed an unbiased transcriptomic analysis on human retinal microvascular endothelial cells(HRECs)and revealed a pivotal role of EMC1 in theβ-catenin signaling pathway.Further in-vitro and in-vivo experiments proved that loss of EMC1 led to compromisedβ-catenin signaling activity through reduced expression of Wnt receptor FZD4,which could be restored by lithium chloride(LiCl)treatment.Driven by these findings,we screened genomic DNA samples from familial exudative vitreoretinopathy(FEVR)patients and identified one heterozygous variant in EMC1 that co-segregated with FEVR phenotype in the family.In-vitro expression experiments revealed that this variant allele failed to facilitate the expression of FZD4 on the plasma membrane and activate theβ-catenin signaling pathway,which might be a main cause of FEVR.In conclusion,our findings reveal that variants in EMC1 gene cause compromisedβ-catenin signaling activity,which may be associated with the pathogenesis of FEVR.展开更多
The endoplasmic reticulum(ER)membrane protein complex(EMC)is responsible for monitoring the biogenesis and synthetic quality of membrane proteins with tail-anchored or multiple transmembrane domains.The EMC subunit EM...The endoplasmic reticulum(ER)membrane protein complex(EMC)is responsible for monitoring the biogenesis and synthetic quality of membrane proteins with tail-anchored or multiple transmembrane domains.The EMC subunit EMC6 is one of the core members of EMC and forms an enclosed hydrophilic vestibule in cooperation with EMC3.Despite studies demonstrating that deletion of EMC3 led to rhodopsin mislocalization in rod photoreceptors of mice,the precise mechanism leading to the failure of rhodopsin trafficking remains unclear.Here,we generated the first rod photoreceptor-specific knockout of Emc6(RKO)and cone photoreceptor-specific knockout of Emc6(CKO)mouse models.Deficiency of Emc6 in rod photoreceptors led to progressive shortening of outer segments(OS),impaired visual function,mislocalization and reduced expression of rhodopsin,and increased gliosis in rod photoreceptors.In addition,CKO mice displayed the progressive death of cone photoreceptors and abnormal localization of cone opsin protein.Subsequently,proteomics analysis of the RKO mouse retina illustrated that several cilium-related proteins,particularly anoctamin-2(ANO2)and transmembrane protein 67(TMEM67),were significantly down-regulated prior to OS degeneration.Detrimental rod photoreceptor cilia and mislocalized membrane disc proteins were evident in RKO mice.Our data revealed that in addition to monitoring the synthesis of rhodopsin-dominated membrane disc proteins,EMC6 also impacted rod photoreceptors'ciliogenesis by regulating the synthesis of membrane proteins associated with cilia,contributing to the mislocalization of membrane disc proteins.展开更多
基金supported by the National Natural Science Foundation of China(82121003,81970841,and 81790643)the Department of Science and Technology of Sichuan Province(2021YFS0386,2021YFS0369,20ZYD038,20ZYD037,2020JDZH0026,2021JDZH0022)+2 种基金the CAMS Innovation Fund for Medical Sciences(2019-12M-5-032)Huanhua Distingished Scholar grantthe Department of Chengdu Science and Technology(2021-YF05-01316-SN)。
文摘N^(6)-methyladenosine(m^(6)A)modification,which is achieved by the METTL3/METTL14/WTAP methyltransferase complex,is the most abundant internal mRNA modification.Although recent evidence indicates that m^(6)A can regulate neurodevelopment as well as synaptic function,the roles of m^(6)A modification in the cerebellum and related synaptic connections are not well established.Here,we report that Purkinje cell(PC)-specific WTAP knockout mice display early-onset ataxia concomitant with cerebellar atrophy due to extensive PC degeneration and apoptotic cell death.Loss of Wtap also causes the aberrant degradation of multiple PC synapses.WTAP depletion leads to decreased expression levels of METTL3/14 and reduced m^(6)A methylation in PCs.Moreover,the expression of GFAP and NF-L in the degenerating cerebellum is increased,suggesting severe neuronal injuries.In conclusion,this study demonstrates the critical role of WTAP-mediated m^(6)A modification in cerebellar PCs,thus providing unique insights related to neurodegenerative disorders.
基金supported by the National Natural Science Foundation of China(81970841,82101160,82121003)the Department of Science and Technology of Sichuan Province(2023ZYD0172,2023YFS0161)+3 种基金the program of Science and Technology International Cooperation Project of Qinghai province(China)(No.2022-HZ-814)Sichuan Intellectual Property Office(China)(No.2022-ZS-0070)the CAMS Innovation Fund for Medical Sciences(2019-12M-5-032)Open Project of Henan Provincial Key Laboratory of Ophthalmology and Visual Science(20KFKT02).
文摘Inherited retinal dystrophies (IRDs) are major causes of visual impairment and irreversible blindness worldwide, while the precise molecular and genetic mechanisms are still elusive. N6-methyladenosine (m^(6)A) modification is the most prevalent internal modification in eukaryotic mRNA. YTH domain containing 2 (YTHDC2), an m^(6)A reader protein, has recently been identified as a key player in germline development and human cancer. However, its contribution to retinal function remains unknown. Here, we explore the role of YTHDC2 in the visual function of retinal rod photoreceptors by generating rod-specific Ythdc2 knockout mice. Results show that Ythdc2 deficiency in rods causes diminished scotopic ERG responses and progressive retinal degeneration. Multi-omics analysis further identifies Ppef2 and Pde6b as the potential targets of YTHDC2 in the retina. Specifically, via its YTH domain, YTHDC2 recognizes and binds m^(6)A-modified Ppef2 mRNA at the coding sequence and Pde6b mRNA at the 5′-UTR, resulting in enhanced translation efficiency without affecting mRNA levels. Compromised translation efficiency of Ppef2 and Pde6b after YTHDC2 depletion ultimately leads to decreased protein levels in the retina, impaired retinal function, and progressive rod death. Collectively, our finding highlights the importance of YTHDC2 in visual function and photoreceptor survival, which provides an unreported elucidation of IRD pathogenesis via epitranscriptomics.
基金supported by the National Natural Science Foundation of China(81970841 and 81770950 to X.Zhu,81790643 and 82121003 to Z.Yang,82000913 to S.Li,82101153 to M.Yang)the CAMS Innovation Fund for Medical Sciences(2019-12M-5-032 to Z.Yang)+3 种基金the Department of Science and Technology of Sichuan Province(2021YFS0386 to X.Zhu,2022YFS0598 to S.Li,2021YFS0369 and 2021JDGD0036 to Z.Yang)The Program of Science and Technology International Cooperation Project of Qinghai province(2022-HZ-814 to X.Zhu)the fund for Sichuan Provincial People’s Hospital(2021QN01 to M.Yang)the Department of Chengdu Science and Technology(2021-YF05-01316-SN to X.Zhu)。
文摘Familial exudative vitreoretinopathy(FEVR),an inherited eye disease,is characterized by abnormal retinal vascular development,such as neovascularization,vitreous hemorrhage,exudation,and retinal detachment(Criswick and Schepens,1969;Robitaille et al.,2002).FEVR is inherited as autosomal dominant,autosomal recessive,and X-linked patterns(de Crecchio et al.,1998).
基金This work was supported by the National Natural Science Foundation of China(81970841,81770950,81790643,82000913,and 82071009)the Department of Science and Technology of Sichuan Province(2020JDZH0027 and 2020ZYD037)+2 种基金the CAMS Innovation Fund for Medical Sciences(2019-12M-5-032)the fund for Sichuan Provincial People’s Hospital(2021QN01)the Chengdu Science and Technology Bureau(2019-YF05-00572-SN).
文摘The endoplasmic reticulum(ER) membrane protein complex(EMC) regulates the synthesis and quality control of membrane proteins with multiple transmembrane domains. One of the membrane spanning subunits, EMC3, is a core member of the EMC complex that provides essential hydrophilic vestibule for substrate insertion. Here, we show that the EMC subunit Emc3 plays critical roles in the retinal vascular angiogenesis by regulating Norrin/Wnt signaling. Postnatal endothelial cell(EC)-specific deletion of Emc3 led to retarded retinal vascular development with a hyperpruned vascular network, the appearance of bluntended, aneurysm-like tip endothelial cells(ECs) with reduced numbers of filopodia and leakage of erythrocytes at the vascular front. Diminished tube formation and cell proliferation were also observed in EMC3 depleted human retinal endothelial cells(HRECs). We then discovered a critical role for EMC3 in expression of FZD4 receptor of β-catenin signaling using RNA sequencing, real-time quantitative PCR(RT-q PCR) and luciferase reporter assay. Moreover, augmentation of Wnt activity via lithium chloride(Li Cl) treatment remarkably enhanced β-catenin signaling and cell proliferation of HRECs. Additionally, Li Cl partially reversed the angiogenesis defects in Emc3-c KO mice. Our data reveal that Emc3 plays essential roles in angiogenesis through direct control of FZD4 expression and Norrin/β-catenin signaling.
基金supported by the National Natural Science Foundation of China(No.82101153,82000913,81970841,82121003,and 82071009)the Sichuan Science and Technology Program,China(No.2022YFS0598,2021YFS0386,2021YFS0369,and 2021JDGD0036)+4 种基金the CAMS Innovation Fund for Medical Sciences,China(No.2019-12M-5-032)the Department of Science and Technology of Qinghai Province,China(No.2022-HZ-814)the fund for Sichuan Provincial People's Hospital,China(No.2021QN01)the Department of Chengdu Science and Technology,China(No.2021-YF05-01316-SN)the Huanhua Outstanding Scholar Program for Sichuan Provincial People's Hospital(China)to Xianjun Zhu.The funders had no role in the study design,data collection,analysis,or preparation of the manuscript.
文摘Endoplasmic reticulum(ER)membrane protein complex(EMC)is required for the co-translational insertion of newly synthesized multi-transmembrane proteins.Compromised EMC function in different cell types has been implicated in multiple diseases.Using inducible genetic mouse models,we revealed defects in retinal vascularization upon endothelial cell(EC)specific deletion of Emc1,the largest subunit of EMC.Loss of Emc1 in ECs led to reduced vascular progression and vascular density,diminished tip cell sprouts,and vascular leakage.We then performed an unbiased transcriptomic analysis on human retinal microvascular endothelial cells(HRECs)and revealed a pivotal role of EMC1 in theβ-catenin signaling pathway.Further in-vitro and in-vivo experiments proved that loss of EMC1 led to compromisedβ-catenin signaling activity through reduced expression of Wnt receptor FZD4,which could be restored by lithium chloride(LiCl)treatment.Driven by these findings,we screened genomic DNA samples from familial exudative vitreoretinopathy(FEVR)patients and identified one heterozygous variant in EMC1 that co-segregated with FEVR phenotype in the family.In-vitro expression experiments revealed that this variant allele failed to facilitate the expression of FZD4 on the plasma membrane and activate theβ-catenin signaling pathway,which might be a main cause of FEVR.In conclusion,our findings reveal that variants in EMC1 gene cause compromisedβ-catenin signaling activity,which may be associated with the pathogenesis of FEVR.
基金supported by The National Natural Science Foundation of China(No.82121003,81970841,82101160)the program of Science and Technology International Cooperation Project of Qinghai province(China)(No.2022-HZ-814)+2 种基金the CAMS Innovation Fund for Medical Sciences(No.2019-12M-5-032)Sichuan Intellectual Property Office(China)(No.2022-ZS-0070)the Department of Chengdu Science and Technology(Sichuan,China)(No.2021-YF05-01316-SN).
文摘The endoplasmic reticulum(ER)membrane protein complex(EMC)is responsible for monitoring the biogenesis and synthetic quality of membrane proteins with tail-anchored or multiple transmembrane domains.The EMC subunit EMC6 is one of the core members of EMC and forms an enclosed hydrophilic vestibule in cooperation with EMC3.Despite studies demonstrating that deletion of EMC3 led to rhodopsin mislocalization in rod photoreceptors of mice,the precise mechanism leading to the failure of rhodopsin trafficking remains unclear.Here,we generated the first rod photoreceptor-specific knockout of Emc6(RKO)and cone photoreceptor-specific knockout of Emc6(CKO)mouse models.Deficiency of Emc6 in rod photoreceptors led to progressive shortening of outer segments(OS),impaired visual function,mislocalization and reduced expression of rhodopsin,and increased gliosis in rod photoreceptors.In addition,CKO mice displayed the progressive death of cone photoreceptors and abnormal localization of cone opsin protein.Subsequently,proteomics analysis of the RKO mouse retina illustrated that several cilium-related proteins,particularly anoctamin-2(ANO2)and transmembrane protein 67(TMEM67),were significantly down-regulated prior to OS degeneration.Detrimental rod photoreceptor cilia and mislocalized membrane disc proteins were evident in RKO mice.Our data revealed that in addition to monitoring the synthesis of rhodopsin-dominated membrane disc proteins,EMC6 also impacted rod photoreceptors'ciliogenesis by regulating the synthesis of membrane proteins associated with cilia,contributing to the mislocalization of membrane disc proteins.
