LIN28 is an RNA binding protein with important roles in early embryo development,stem cell differentiation/re-programming,tumorigenesis and metabolism.Previous studies have focused mainly on its role in the cytosol wh...LIN28 is an RNA binding protein with important roles in early embryo development,stem cell differentiation/re-programming,tumorigenesis and metabolism.Previous studies have focused mainly on its role in the cytosol where it interacts with Let-7 microRNA precursors or mRNAs,and few have addressed LIN28's role within the nucleus.Here,we show that LIN28 displays dynamic temporal and spatial expression during murine embryo development.Maternal LIN28 expression drops upon exit from the 2-cell stage,and zygotic LIN28 protein is induced at the forming nucleolus during 4-cell to blas-tocyst stage development,to become dominantly expressed in the cytosol after implantation.In cultured pluripotent stem cells(PSCs),loss of LIN28 led to nucleolar stress and activation of a 2-cell/4-cell-like transcriptional program characterized by the expression of endogenous retrovirus genes.Mechanistically,LIN28 binds to small nucleolar RNAs and rRNA to maintain nucleolar integrity,and its loss leads to nucleolar phase separation defects,ribosomal stress and activation of P53 which in turn binds to and activates 2C transcription factor Dux.LIN28 also resides in a complex containing the nucleolar factor Nucleolin(NCL)and the transcrip-tional repressor TRIM28,and LIN28 loss leads to reduced occupancy of the NCL/TRIM28 complex on the Dux and rDNA loci,and thus de-repressed Dux and reduced rRNA expression.Lin28 knockout cells with nucleolar stress are more likely to assume a slowly cycling,translationally inert and anabolically inactive state,which is a part of previously unappreciated 2C-like transcriptional program.These findings elucidate novel roles for nucleolar LIN28 in PSCs,and a new mechanism linking 2C program and nucleolar functions in PSCs and early embryo development.展开更多
AIM:To evaluate the effects of LIN28A(human)on high glucose-induced retinal pigmented epithelium(RPE)cell injury and its possible mechanism.METHODS:Diabetic retinopathy model was generated following 48h of exposure to...AIM:To evaluate the effects of LIN28A(human)on high glucose-induced retinal pigmented epithelium(RPE)cell injury and its possible mechanism.METHODS:Diabetic retinopathy model was generated following 48h of exposure to 30 mmol/L high glucose(HG)in ARPE-19 cells.Quantitative real-time polymerase chain reaction(qRT-PCR)and Western blot tested the expression of the corresponding genes and proteins.Cell viability as well as apoptosis was determined through cell counting kit-8(CCK-8)and flow cytometry assays.Immunofluorescence assay was adopted to evaluate autophagy activity.Caspase 3 activity,oxidative stress markers,and cytokines were appraised adopting their commercial kits,respectively.Finally,ARPE-19 cells were preincubated with EX527,a Sirtuin 1(SIRT1)inhibitor,prior to HG stimulation to validate the regulatory mechanism.RESULTS:LIN28A was downregulated in HG-challenged ARPE-19 cells.LIN28A overexpression greatly inhibited HGinduced ARPE-19 cell viability loss,apoptosis,oxidative damage as well as inflammatory response.Meanwhile,the repressed autophagy and SIRT1 in ARPE-19 cells challenged with HG were elevated after LIN28A overexpression.In addition,treatment of EX527 greatly inhibited the activated autophagy following LIN28A overexpression and partly abolished the protective role of LIN28A against HG-elicited apoptosis,oxidative damage as well as inflammation in ARPE-19 cells.CONCLUSION:LIN28A exerts a protective role against HG-elicited RPE oxidative damage,inflammation,as well as apoptosis via regulating SIRT1/autophagy.展开更多
LIN28A,an RNA-binding protein,plays an important role in porcine induced pluripotent stem cells(piPSCs).However,the molecular mechanism underlying the function of LIN28A in the maintenance of pluripotency in piPSCs re...LIN28A,an RNA-binding protein,plays an important role in porcine induced pluripotent stem cells(piPSCs).However,the molecular mechanism underlying the function of LIN28A in the maintenance of pluripotency in piPSCs remains unclear.Here,we explored the function of LIN28A in piPSCs based on its overexpression and knockdown.We performed total RNA sequencing(RNA-seq)of piPSCs and detected the expression levels of relevant genes by quantitative real-time polymerase chain reaction(qRT-PCR),western blot analysis,and immunofluorescence staining.Results indicated that piPSC proliferation ability decreased following LIN28A knockdown.Furthermore,when LIN28A expression in the shLIN28A2 group was lower(by 20%)than that in the negative control knockdown group(shNC),the pluripotency of piPSCs disappeared and they differentiated into neuroectoderm cells.Results also showed that LIN28A overexpression inhibited the expression of DUSP(dual-specificity phosphatases)family phosphatases and activated the mitogen-activated protein kinase(MAPK)signaling pathway.Thus,LIN28A appears to activate the MAPK signaling pathway to maintain the pluripotency and proliferation ability of piPSCs.Our study provides a new resource for exploring the functions of LIN28A in piPSCs.展开更多
基金We thank Hengyu Fan,Dan Zhang,Jianzhong Sheng,Pengfei Xu and Hua Lu for discussing and sharing facilities.J.Z.is supported by the National Key Research and Development Program of China(2018YFA0107100,2018YFA0107103,2018YFC1005002)the National Natural Science Foundation projects of China(31871453,91857116)+3 种基金the Zhejiang Natural Science Foundation projects of China(LR19C120001)High-Performance Computing Platform in Center of Cryo-Electron Microscopy of Zhejiang University and core facilities,Zhejiang University School of Medicine.H.Y.is supported by the Zhejiang Natural Science Foundation Projects of China(Grant No.LQ21C120002)J.W.is supported by National Institutes of Health(HD097268)New York State Stem Cell Science(C32569GG).
文摘LIN28 is an RNA binding protein with important roles in early embryo development,stem cell differentiation/re-programming,tumorigenesis and metabolism.Previous studies have focused mainly on its role in the cytosol where it interacts with Let-7 microRNA precursors or mRNAs,and few have addressed LIN28's role within the nucleus.Here,we show that LIN28 displays dynamic temporal and spatial expression during murine embryo development.Maternal LIN28 expression drops upon exit from the 2-cell stage,and zygotic LIN28 protein is induced at the forming nucleolus during 4-cell to blas-tocyst stage development,to become dominantly expressed in the cytosol after implantation.In cultured pluripotent stem cells(PSCs),loss of LIN28 led to nucleolar stress and activation of a 2-cell/4-cell-like transcriptional program characterized by the expression of endogenous retrovirus genes.Mechanistically,LIN28 binds to small nucleolar RNAs and rRNA to maintain nucleolar integrity,and its loss leads to nucleolar phase separation defects,ribosomal stress and activation of P53 which in turn binds to and activates 2C transcription factor Dux.LIN28 also resides in a complex containing the nucleolar factor Nucleolin(NCL)and the transcrip-tional repressor TRIM28,and LIN28 loss leads to reduced occupancy of the NCL/TRIM28 complex on the Dux and rDNA loci,and thus de-repressed Dux and reduced rRNA expression.Lin28 knockout cells with nucleolar stress are more likely to assume a slowly cycling,translationally inert and anabolically inactive state,which is a part of previously unappreciated 2C-like transcriptional program.These findings elucidate novel roles for nucleolar LIN28 in PSCs,and a new mechanism linking 2C program and nucleolar functions in PSCs and early embryo development.
基金Supported by Medical and Health Science and Technology Project of Zhejiang Province(No.2023KY1356).
文摘AIM:To evaluate the effects of LIN28A(human)on high glucose-induced retinal pigmented epithelium(RPE)cell injury and its possible mechanism.METHODS:Diabetic retinopathy model was generated following 48h of exposure to 30 mmol/L high glucose(HG)in ARPE-19 cells.Quantitative real-time polymerase chain reaction(qRT-PCR)and Western blot tested the expression of the corresponding genes and proteins.Cell viability as well as apoptosis was determined through cell counting kit-8(CCK-8)and flow cytometry assays.Immunofluorescence assay was adopted to evaluate autophagy activity.Caspase 3 activity,oxidative stress markers,and cytokines were appraised adopting their commercial kits,respectively.Finally,ARPE-19 cells were preincubated with EX527,a Sirtuin 1(SIRT1)inhibitor,prior to HG stimulation to validate the regulatory mechanism.RESULTS:LIN28A was downregulated in HG-challenged ARPE-19 cells.LIN28A overexpression greatly inhibited HGinduced ARPE-19 cell viability loss,apoptosis,oxidative damage as well as inflammatory response.Meanwhile,the repressed autophagy and SIRT1 in ARPE-19 cells challenged with HG were elevated after LIN28A overexpression.In addition,treatment of EX527 greatly inhibited the activated autophagy following LIN28A overexpression and partly abolished the protective role of LIN28A against HG-elicited apoptosis,oxidative damage as well as inflammation in ARPE-19 cells.CONCLUSION:LIN28A exerts a protective role against HG-elicited RPE oxidative damage,inflammation,as well as apoptosis via regulating SIRT1/autophagy.
基金This work was supported by the National Key Research,Development Program of China-Stem Cell and Translational Research(2016YFA0100200)National Natural Science Foundation of China(32072806,31572399,61772431,62072377)+1 种基金Program of Shaanxi Province Science and Technology Innovation Team(2019TD-036)Fundamental Research Funds for the Central Universities,Northwest A&F University(Z1090219146,Z102022004)。
文摘LIN28A,an RNA-binding protein,plays an important role in porcine induced pluripotent stem cells(piPSCs).However,the molecular mechanism underlying the function of LIN28A in the maintenance of pluripotency in piPSCs remains unclear.Here,we explored the function of LIN28A in piPSCs based on its overexpression and knockdown.We performed total RNA sequencing(RNA-seq)of piPSCs and detected the expression levels of relevant genes by quantitative real-time polymerase chain reaction(qRT-PCR),western blot analysis,and immunofluorescence staining.Results indicated that piPSC proliferation ability decreased following LIN28A knockdown.Furthermore,when LIN28A expression in the shLIN28A2 group was lower(by 20%)than that in the negative control knockdown group(shNC),the pluripotency of piPSCs disappeared and they differentiated into neuroectoderm cells.Results also showed that LIN28A overexpression inhibited the expression of DUSP(dual-specificity phosphatases)family phosphatases and activated the mitogen-activated protein kinase(MAPK)signaling pathway.Thus,LIN28A appears to activate the MAPK signaling pathway to maintain the pluripotency and proliferation ability of piPSCs.Our study provides a new resource for exploring the functions of LIN28A in piPSCs.
