Liver is one of the largest internal organs in the body and its importance for metabolism, detoxification and homeostasis has been well established. In this review, we summarized recent progresses in studying liver in...Liver is one of the largest internal organs in the body and its importance for metabolism, detoxification and homeostasis has been well established. In this review, we summarized recent progresses in studying liver initiation and development during embryogenesis using zebrafish as a model system. We mainly focused on topics related to the specification of hepatoblasts from endoderm, the formation and growth of liver bud, the differentiation of hepatocytes and bile duct cells from hepatoblasts, and finally the role of mesodermal signals in controlling liver development in zebrafish.展开更多
Ribosome biogenesis in the nucleolus requires numerous nucleolar proteins and small non-coding RNAs.Among them is ribosome biogenesis factor Bmsl,which is highly conserved from yeast to human.In yeast,Bmsl initiates r...Ribosome biogenesis in the nucleolus requires numerous nucleolar proteins and small non-coding RNAs.Among them is ribosome biogenesis factor Bmsl,which is highly conserved from yeast to human.In yeast,Bmsl initiates ribosome biogenesis through recruiting Rcll to pre-ribosomes.However,little is known about the biological function of Bmsl in vertebrates.Here we report that Bmsl plays an essential role in zebrafish liver development.We identified a zebrafish bms1l^（sq163） mutant which carries a T to A mutation in the gene bmsl-like（bms1l）.This mutation results in L^（152） to Q^（152） substitution in a GTPase motif in Bmsll.Surprisingly,bmsll^（sq163） mutation confers hypoplasia specifically in the liver,exocrine pancreas and intestine after 3 days post-fertilization（dpf）.Consistent with the bmsll^（sq163） mutant phenotypes,whole-mount in situ hybridization（WISH） on wild type embryos showed that bmsll transcripts are abundant in the entire digestive tract and its accessory organs.Immunostaining for phospho-Histone 3（P-H3） and TUNEL assay revealed that impairment of hepatoblast proliferation rather than cell apoptosis is one of the consequences of bms1l（sq163） giving rise to an under-developed liver.Therefore,our findings demonstrate that Bmsll is necessary for zebrafish liver development.展开更多
Human stem cells are scalable cell populations capable of cellular differentiation.This makes them a very attractive in vitro cellular resource and in theory provides unlimited amounts of primary cells.Such an approac...Human stem cells are scalable cell populations capable of cellular differentiation.This makes them a very attractive in vitro cellular resource and in theory provides unlimited amounts of primary cells.Such an approach has the potential to improve our understanding of human biology and treating disease.In the future it may be possible to deploy novel stem cell-based approaches to treat human liver diseases.In recent years,eff icient hepatic differentiation from human stem cells has been achieved by several research groups including our own.In this review we provide an overview of the f ield and discuss the future potential and limitations of stem cell technology.展开更多
CYP2D6 expression in liver is age-dependent.Because epigenetic mechanisms,such as DNA methylation and histone modifications,modulate age-related gene expression during development,and are highly conserved among specie...CYP2D6 expression in liver is age-dependent.Because epigenetic mechanisms,such as DNA methylation and histone modifications,modulate age-related gene expression during development,and are highly conserved among species,the current study examined the epigenetic regulation of age-related expression of the Cyp2d genes in mouse liver.DNA methylation(DNAme),histone 3 lysine 4 dimethylation(H3K4me2),and histone 3 lysine 27 trimethylation(H3K27me3)was established by ChIP-on-chip tiling microarrays from mouse livers at prenatal,neonatal,and adult stages.Levels of DNAme,H3K4me2,and H3K27me3 were analyzed in a genomic region containing the Cyp2d clustering genes and their surrounding genes.Gradually increased expression levels of the Cyp2d9,Cyp2d10,Cyp2d22,and Cyp2d26 genes from prenatal,through neonatal,to adult are associated with gradually increased levels of H3K4me2 in the nucleosomes associated with these genes.Gene expression patterns during liver development in several Cyp2d surrounding genes,such as Srebf2,Sept3,Ndufa6,Tcf2,Nfam1,and Cyb5r3,could be also explained by changes of DNA methylation,H3K4me2,or H3K27me3 in those genes.In conclusion,the current study demonstrates that the changes of DNA methylation and histone modifications are associated with age-related expression patterns of the Cyp2d genes and their surrounding genes in liver cells during development.展开更多
As the most abundant liver-specific microRNA,mi-croRNA-122(miR-122)is involved in various physio-logical processes in hepatic function as well as in liver pathology.There is now compelling evidence that miR-122,as a r...As the most abundant liver-specific microRNA,mi-croRNA-122(miR-122)is involved in various physio-logical processes in hepatic function as well as in liver pathology.There is now compelling evidence that miR-122,as a regulator of gene networks and pathways in hepatocytes,plays a central role in diverse aspects of hepatic function and in the progress of liver diseases.This liver-enriched transcription factors-regulated miRNA promotes differentiation of hepatocytes and regulates lipid metabolism.With regard to liver diseases,miR-122 was shown to stimulate hepatitis C virus(HCV)replication through a unique and unusual interaction with two binding sites in the 5′-UTR of HCV genome to mediate the stability of the viral RNA,whereas inhibit the expression and replication of hepatitis B virus(HBV)by a miR-122-cylin G1/p53-HBV enhancer regulatory pathway.In addition,miR-122 acts as a suppressor of cell prolif-eration and malignant transformation of hepatocytes with remarkable tumor inhibition activity.Notably,a clinical trial targeting miR-122 with the anti-miR-122 oli-gonucleotides miravirsen,the first miRNA targeted drug,has been initiated for treatment of HCV infection.With further understanding of the comprehensive roles of miR-122 in hepatic functions and the mechanisms in-volved in miR-122 down-regulation in chronic hepatitis or hepatocellular carcinoma,miR-122 appears to be a promising candidate for effective therapeutic ap-proaches against tumor and infectious diseases.展开更多
In mammals,the expression of the homeobox family member Cdx2/CDX2 is restricted within the intestine.Conditional ablation of the mouse Cdx2 in the endodermal cells causes a homeotic transformation of the intestine tow...In mammals,the expression of the homeobox family member Cdx2/CDX2 is restricted within the intestine.Conditional ablation of the mouse Cdx2 in the endodermal cells causes a homeotic transformation of the intestine towards the esophagus or gastric fate.In this report,we show that null mutants of zebrafish cdx1b,encoding the counterpart of mammalian CDX2,could survive more than 10 days post fertilization,a stage when the zebrafish digestive system has been well developed.Through RNA sequencing(RNA-seq)and single-cell sequencing(sc RNA-seq)of the dissected intestine from the mutant embryos,we demonstrate that the loss-of-function of the zebrafish cdx1b yields hepatocyte-like intestinal cells,a phenotype never observed in the mouse model.Further RNA-seq data analysis,and genetic double mutants and signaling inhibitor studies reveal that Cdx1b functions to guard the intestinal fate by repressing,directly or indirectly,a range of transcriptional factors and signaling pathways for liver specification.Finally,we demonstrate that heat shock-induced overexpression of cdx1b in a transgenic fish abolishes the liver formation.Therefore,we demonstrate that Cdx1b is a key repressor of hepatic fate during the intestine specification in zebrafish.展开更多
Spatial transcriptomics,which combine gene expression data with spatial information,has quickly expanded in recent years.With application of this method in liver research,our knowledge about liver development,regenera...Spatial transcriptomics,which combine gene expression data with spatial information,has quickly expanded in recent years.With application of this method in liver research,our knowledge about liver development,regeneration,and diseases have been greatly improved.While this field is moving forward,a variety of problems still need to be addressed,including sensitivity,limited capacity to obtain exact single-cell information,data processing methods,as well as others.Methods like single-cell RNA sequencing(scRNA-seq)are usually used together with spatial transcriptome sequencing(ST-seq)to clarify cell-specific gene expression.In this review,we explore how advances of scRNA-seq and ST-seq,especially ST-seq,will pave the way to new opportunities to investigate fundamental questions in liver research.Finally,we will discuss the strengths,limitations,and future perspectives of ST-seq in liver research.展开更多
During ribosome biogenesis,the small subunit(SSU)processome is responsible for 40S assembly.The BMS1/RCL1 complex is a core component of the SSU processome that plays an important role in 18S rRNA processing and matur...During ribosome biogenesis,the small subunit(SSU)processome is responsible for 40S assembly.The BMS1/RCL1 complex is a core component of the SSU processome that plays an important role in 18S rRNA processing and maturation.Genetic studies using zebrafish mutants indicate that both Bms1-like(Bms1l)and Rcl1 are essential for digestive organ development.In spite of vital functions of this complex,the mutual dependence of these two nucleolar proteins for the stability and function remains elusive.In this study,we identified an RCL1-interacting domain in BMS1,which is conserved in zebrafish and humans.Moreover,both the protein stability and nucleolar entry of RCL1 depend on its interaction with BMS1,otherwise RCL1 degraded through the ubiquitination-proteasome pathway.Functional studies revealed that overexpression of RCL1 in BMS1-knockdown cells can partially rescue the defects in 18S rRNA processing and cell proliferation,and hepatocyte-specific overexpression of Rcl1 can resume zebrafish liver development in the bms1l substitution mutant bms1l^(sq163/sq163)but not in the knockout mutant bms1l^(zju1/zju1),which is attributed to the nucleolar entry of Rcl1 in the former mutant.Our data demonstrate that BMS1 and RCL1 interaction is essential for not only pre-rRNA processing but also the communication between ribosome biogenesis and cell cycle regulation.展开更多
The liver is the largest internal organ in mammals,and is important for the maintenance of normal physiological functions of other tissues and organs.Hepatitis,cirrhosis,liver cancer and other chronic liver diseases a...The liver is the largest internal organ in mammals,and is important for the maintenance of normal physiological functions of other tissues and organs.Hepatitis,cirrhosis,liver cancer and other chronic liver diseases are serious threats to human health,and these problems are compounded by a scarcity of liver donors for transplantation therapies.Directed differentiation of embryonic stem cells to liver cells is a promising strategy for obtaining hepatocytes that can be used for cell transplantation.In vitro hepatocyte differentiation of embryonic stem cells requires a profound understanding of normal development during embryonic hepatogenesis.Here we provide a simple description of hepatogenesis in vivo and discuss directed differentiation of embryonic stem cells into hepatocytes in vitro.展开更多
基金supported by the National Natural Science Foundation of China (No. 30825025)
文摘Liver is one of the largest internal organs in the body and its importance for metabolism, detoxification and homeostasis has been well established. In this review, we summarized recent progresses in studying liver initiation and development during embryogenesis using zebrafish as a model system. We mainly focused on topics related to the specification of hepatoblasts from endoderm, the formation and growth of liver bud, the differentiation of hepatocytes and bile duct cells from hepatoblasts, and finally the role of mesodermal signals in controlling liver development in zebrafish.
基金supported by the grants from the National Natural Science Foundation of China(NSFC)(No.31171391) to LJLan NSFC grant(No. 30825025) to JRP and a grant from the National Research Foundation of Singapore(R-154-000-529-281) to YHH
文摘Ribosome biogenesis in the nucleolus requires numerous nucleolar proteins and small non-coding RNAs.Among them is ribosome biogenesis factor Bmsl,which is highly conserved from yeast to human.In yeast,Bmsl initiates ribosome biogenesis through recruiting Rcll to pre-ribosomes.However,little is known about the biological function of Bmsl in vertebrates.Here we report that Bmsl plays an essential role in zebrafish liver development.We identified a zebrafish bms1l^（sq163） mutant which carries a T to A mutation in the gene bmsl-like（bms1l）.This mutation results in L^（152） to Q^（152） substitution in a GTPase motif in Bmsll.Surprisingly,bmsll^（sq163） mutation confers hypoplasia specifically in the liver,exocrine pancreas and intestine after 3 days post-fertilization（dpf）.Consistent with the bmsll^（sq163） mutant phenotypes,whole-mount in situ hybridization（WISH） on wild type embryos showed that bmsll transcripts are abundant in the entire digestive tract and its accessory organs.Immunostaining for phospho-Histone 3（P-H3） and TUNEL assay revealed that impairment of hepatoblast proliferation rather than cell apoptosis is one of the consequences of bms1l（sq163） giving rise to an under-developed liver.Therefore,our findings demonstrate that Bmsll is necessary for zebrafish liver development.
基金Supported by A RCUK fellowship,EP/E500145/1,to Hay DCA grant from the Edinburgh Bioquarter,to Medine CNChina Scholarship Council,No.2010658022,to Zhou WL
文摘Human stem cells are scalable cell populations capable of cellular differentiation.This makes them a very attractive in vitro cellular resource and in theory provides unlimited amounts of primary cells.Such an approach has the potential to improve our understanding of human biology and treating disease.In the future it may be possible to deploy novel stem cell-based approaches to treat human liver diseases.In recent years,eff icient hepatic differentiation from human stem cells has been achieved by several research groups including our own.In this review we provide an overview of the f ield and discuss the future potential and limitations of stem cell technology.
基金supported by the National Institute of Health(1R01GM087376 and COBRE 5P20 RR021940).
文摘CYP2D6 expression in liver is age-dependent.Because epigenetic mechanisms,such as DNA methylation and histone modifications,modulate age-related gene expression during development,and are highly conserved among species,the current study examined the epigenetic regulation of age-related expression of the Cyp2d genes in mouse liver.DNA methylation(DNAme),histone 3 lysine 4 dimethylation(H3K4me2),and histone 3 lysine 27 trimethylation(H3K27me3)was established by ChIP-on-chip tiling microarrays from mouse livers at prenatal,neonatal,and adult stages.Levels of DNAme,H3K4me2,and H3K27me3 were analyzed in a genomic region containing the Cyp2d clustering genes and their surrounding genes.Gradually increased expression levels of the Cyp2d9,Cyp2d10,Cyp2d22,and Cyp2d26 genes from prenatal,through neonatal,to adult are associated with gradually increased levels of H3K4me2 in the nucleosomes associated with these genes.Gene expression patterns during liver development in several Cyp2d surrounding genes,such as Srebf2,Sept3,Ndufa6,Tcf2,Nfam1,and Cyb5r3,could be also explained by changes of DNA methylation,H3K4me2,or H3K27me3 in those genes.In conclusion,the current study demonstrates that the changes of DNA methylation and histone modifications are associated with age-related expression patterns of the Cyp2d genes and their surrounding genes in liver cells during development.
基金supported by grants from the National Natural Science Foundation of China(Grant Nos.30970146,91029724,and 81021003).
文摘As the most abundant liver-specific microRNA,mi-croRNA-122(miR-122)is involved in various physio-logical processes in hepatic function as well as in liver pathology.There is now compelling evidence that miR-122,as a regulator of gene networks and pathways in hepatocytes,plays a central role in diverse aspects of hepatic function and in the progress of liver diseases.This liver-enriched transcription factors-regulated miRNA promotes differentiation of hepatocytes and regulates lipid metabolism.With regard to liver diseases,miR-122 was shown to stimulate hepatitis C virus(HCV)replication through a unique and unusual interaction with two binding sites in the 5′-UTR of HCV genome to mediate the stability of the viral RNA,whereas inhibit the expression and replication of hepatitis B virus(HBV)by a miR-122-cylin G1/p53-HBV enhancer regulatory pathway.In addition,miR-122 acts as a suppressor of cell prolif-eration and malignant transformation of hepatocytes with remarkable tumor inhibition activity.Notably,a clinical trial targeting miR-122 with the anti-miR-122 oli-gonucleotides miravirsen,the first miRNA targeted drug,has been initiated for treatment of HCV infection.With further understanding of the comprehensive roles of miR-122 in hepatic functions and the mechanisms in-volved in miR-122 down-regulation in chronic hepatitis or hepatocellular carcinoma,miR-122 appears to be a promising candidate for effective therapeutic ap-proaches against tumor and infectious diseases.
基金supported by Centre for Computational Science and Engineering(CCSE)at Southern University of Science and Technologysupported by the National Key R&D Program of China(2018YFA0800502)the National Natural Science Foundation of China(31900579,31830113)。
文摘In mammals,the expression of the homeobox family member Cdx2/CDX2 is restricted within the intestine.Conditional ablation of the mouse Cdx2 in the endodermal cells causes a homeotic transformation of the intestine towards the esophagus or gastric fate.In this report,we show that null mutants of zebrafish cdx1b,encoding the counterpart of mammalian CDX2,could survive more than 10 days post fertilization,a stage when the zebrafish digestive system has been well developed.Through RNA sequencing(RNA-seq)and single-cell sequencing(sc RNA-seq)of the dissected intestine from the mutant embryos,we demonstrate that the loss-of-function of the zebrafish cdx1b yields hepatocyte-like intestinal cells,a phenotype never observed in the mouse model.Further RNA-seq data analysis,and genetic double mutants and signaling inhibitor studies reveal that Cdx1b functions to guard the intestinal fate by repressing,directly or indirectly,a range of transcriptional factors and signaling pathways for liver specification.Finally,we demonstrate that heat shock-induced overexpression of cdx1b in a transgenic fish abolishes the liver formation.Therefore,we demonstrate that Cdx1b is a key repressor of hepatic fate during the intestine specification in zebrafish.
基金funding from NSFC(32071129)Yunnan fundamental research program(202101AT070022,202001AW070006)Double First-Class University Plan(C1762201000142).
文摘Spatial transcriptomics,which combine gene expression data with spatial information,has quickly expanded in recent years.With application of this method in liver research,our knowledge about liver development,regeneration,and diseases have been greatly improved.While this field is moving forward,a variety of problems still need to be addressed,including sensitivity,limited capacity to obtain exact single-cell information,data processing methods,as well as others.Methods like single-cell RNA sequencing(scRNA-seq)are usually used together with spatial transcriptome sequencing(ST-seq)to clarify cell-specific gene expression.In this review,we explore how advances of scRNA-seq and ST-seq,especially ST-seq,will pave the way to new opportunities to investigate fundamental questions in liver research.Finally,we will discuss the strengths,limitations,and future perspectives of ST-seq in liver research.
基金This work was supported by grants fromthe National Natural Science Foundation of China(31771596 and 32000565)。
文摘During ribosome biogenesis,the small subunit(SSU)processome is responsible for 40S assembly.The BMS1/RCL1 complex is a core component of the SSU processome that plays an important role in 18S rRNA processing and maturation.Genetic studies using zebrafish mutants indicate that both Bms1-like(Bms1l)and Rcl1 are essential for digestive organ development.In spite of vital functions of this complex,the mutual dependence of these two nucleolar proteins for the stability and function remains elusive.In this study,we identified an RCL1-interacting domain in BMS1,which is conserved in zebrafish and humans.Moreover,both the protein stability and nucleolar entry of RCL1 depend on its interaction with BMS1,otherwise RCL1 degraded through the ubiquitination-proteasome pathway.Functional studies revealed that overexpression of RCL1 in BMS1-knockdown cells can partially rescue the defects in 18S rRNA processing and cell proliferation,and hepatocyte-specific overexpression of Rcl1 can resume zebrafish liver development in the bms1l substitution mutant bms1l^(sq163/sq163)but not in the knockout mutant bms1l^(zju1/zju1),which is attributed to the nucleolar entry of Rcl1 in the former mutant.Our data demonstrate that BMS1 and RCL1 interaction is essential for not only pre-rRNA processing but also the communication between ribosome biogenesis and cell cycle regulation.
基金Grant support includes China National Basic Research Program(Grant No.2007CB947800)the Shanghai Leading Academic Discipline Project(S30201)STCSM Project(08dj1400502 and 10140900200).
文摘The liver is the largest internal organ in mammals,and is important for the maintenance of normal physiological functions of other tissues and organs.Hepatitis,cirrhosis,liver cancer and other chronic liver diseases are serious threats to human health,and these problems are compounded by a scarcity of liver donors for transplantation therapies.Directed differentiation of embryonic stem cells to liver cells is a promising strategy for obtaining hepatocytes that can be used for cell transplantation.In vitro hepatocyte differentiation of embryonic stem cells requires a profound understanding of normal development during embryonic hepatogenesis.Here we provide a simple description of hepatogenesis in vivo and discuss directed differentiation of embryonic stem cells into hepatocytes in vitro.
