Protein degradation through the ubiquitin-proteasome system is the major pathway of non-lysosomal proteolysis of intracellular proteins. It plays important roles in a variety of fundamental cellular processes such as ...Protein degradation through the ubiquitin-proteasome system is the major pathway of non-lysosomal proteolysis of intracellular proteins. It plays important roles in a variety of fundamental cellular processes such as regulation of cell cycle progression, division, development and differentiation, apoptosis, cell trafficking, and modulation of the immune and inflammatory responses. The central element of this system is the covalent linkage of ubiquitin to targeted proteins, which are then recognized by the 26S proteasome, an adenosine triphosphate-dependent, multi-catalytic protease. Damaged, oxidized, or misfolded proteins as well as regulatory proteins that control many critical cellular functions are among the targets of this degradation process. Aberration of this system leads to the dysregulation of cellular homeostasis and the development of multiple diseases. In this review, we described the basic biochemistry and molecular biology of the ubiquitin-proteasome system, and its complex role in the development of inflammatory and autoimmune diseases. In addition, therapies and potential therapeutic targets related to the ubiquitin-proteasome system are discussed as well.展开更多
Transforming growth factor β （TGFβ） controls cellular behavior in embryonic and adult tissues. TGFβ binding to serine/threonine kinase receptors on the plasma membrane activates Smad molecules and additional sign...Transforming growth factor β （TGFβ） controls cellular behavior in embryonic and adult tissues. TGFβ binding to serine/threonine kinase receptors on the plasma membrane activates Smad molecules and additional signaling proteins that together regulate gene expression. In this review, mechanisms and models that aim at explaining the coordination between several components of the signaling network downstream of TGFβ are presented. We discuss how the activity and duration of TGFβ receptor/Smad signaling can be regulated by post-translational modifications that affect the stability of key proteins in the pathway. We highlight finks between these mechanisms and human diseases, such as tissue fibrosis and cancer.展开更多
The last 40 years have witnessed how p53 rose from a viral binding protein to a central factor in both stress responses and tumor suppression.The exquisite regulation of p53 functions is of vital importance for cell f...The last 40 years have witnessed how p53 rose from a viral binding protein to a central factor in both stress responses and tumor suppression.The exquisite regulation of p53 functions is of vital importance for cell fate decisions.Among the multiple layers of mechanisms controlling p53 function,posttranslational modifications (PTMs) represent an efficient and precise way.Major p53 PTMs include phosphorylation,ubiquitination,acetylation,and methylation.Meanwhile,other PTMs like sumoylation,neddylation,O-GlcNAcylation,adenosine diphosphate (ADP)-ribosylation,hydroxylation,and p-hydroxybutyrylation are also shown to play various roles in p53 regulation.By independent action or interaction,PTMs affect p53 stability,conformation,localization,and binding partners.Deregulation of the PTM-related pathway is among the major causes of p53-associated developmental disorders or diseases,especially in cancers.This review focuses on the roles of different p53 modification types and shows how these modifications are orchestrated to produce various outcomes by modulating p53 activities or targeted to treat different diseases caused by p53 dysregulation.展开更多
Transforming growth factor-β （TGF-β） members are key cytokines that control embryogenesis and tissue homeostasis via transmembrane TGF-β type II （TβR II） and type I （TβRI） and serine/threonine kinases recep...Transforming growth factor-β （TGF-β） members are key cytokines that control embryogenesis and tissue homeostasis via transmembrane TGF-β type II （TβR II） and type I （TβRI） and serine/threonine kinases receptors. Aberrant activation of TGF-β signaling leads to diseases, including cancer. In advanced cancer, the TGF-β/SMAD pathway can act as an oncogenic factor driving tumor cell invasion and metastasis, and thus is considered to be a therapeutic target. The activity of TGF-β/SMAD pathway is known to be regulated by ubiquitination at multiple levels. As ubiquitination is reversible, emerging studies have uncovered key roles for ubiquitin-removals on TGF-β signaling components by deubiquitinating enzymes （DUBs）. In this paper, we summarize the latest findings on the DUBs that control the activity of the TGF-β signaling pathway. The regula- tory roles of these DUBs as a driving force for cancer progression as well as their underlying working mech- anisms are also discussed.展开更多
3-Hydroxy-3-methylglutaryl coenzyme A （HMG CoA） reductase produces mevalonate, an important intermediate in the synthesis of cholesterol and essential nonsterol isoprenoids. The reductase is subject to an exorbitant...3-Hydroxy-3-methylglutaryl coenzyme A （HMG CoA） reductase produces mevalonate, an important intermediate in the synthesis of cholesterol and essential nonsterol isoprenoids. The reductase is subject to an exorbitant amount of feedback control through multiple mechanisms that are mediated by sterol and nonsterol end-products of mevalonate metabolism. Here, I will discuss recent advances that shed light on one mechanism for control of reductase, which involves rapid degradation of the enzyme. Accumulation of certain sterols triggers binding of reductase to endoplasmic reticulum （ER） membrane proteins called Insig-1 and Insig-2. Reductase-Insig binding results in recruitment of a membrane-associated ubiquitin ligase called gp78, which initiates ubiquitination of reductase. This ubiquitination is an obligatory reaction for recognition and degradation of reductase from ER membranes by cytosolic 26S proteasomes. Thus, sterol-accelerated degradation of reductase represents an example of how a general cellular process （ER-associated degradation） is used to control an important metabolic pathway （cholesterol synthesis）.展开更多
Post-translational modification is central to protein stability and to the modulation of protein activity. Various types of protein modification, such as phosphorylation, methylation, acetylation, myristoylation, glyc...Post-translational modification is central to protein stability and to the modulation of protein activity. Various types of protein modification, such as phosphorylation, methylation, acetylation, myristoylation, glycosylation, and ubiquitination, have been reported. Among them, ubiquitination distinguishes itself from others in that most of the ubiquitinated proteins are targeted to the 26S proteasome for degradation. The ubiquitin/26S proteasome system constitutes the major protein degradation pathway in the cell. In recent years, the importance of the ubiquitination machinery in the control of numerous eukaryotic cellular functions has been increasingly appreciated. Increasing number of E3 ubiquitin ligases and their substrates, including a variety of essential cellular regulators have been identified. Studies in the past several years have revealed that the ubiquitination system is important for a broad range of plant developmental processes and responses to abiotic and biotic stresses. This review discusses recent advances in the functional analysis of ubiquitination-associated proteins from plants and pathogens that play important roles in plant-microbe interactions.展开更多
Ubiquitination,an important type of protein posttranslational modification(PTM),plays a crucial role in controlling substrate degradation and subsequently mediates the“quantity”and“quality”of various proteins,serv...Ubiquitination,an important type of protein posttranslational modification(PTM),plays a crucial role in controlling substrate degradation and subsequently mediates the“quantity”and“quality”of various proteins,serving to ensure cell homeostasis and guarantee life activities.The regulation of ubiquitination is multifaceted and works not only at the transcriptional and posttranslational levels(phosphorylation,acetylation,methylation,etc.)but also at the protein level(activators or repressors).When regulatory mechanisms are aberrant,the altered biological processes may subsequently induce serious human diseases,especially various types of cancer.In tumorigenesis,the altered biological processes involve tumor metabolism,the immunological tumor microenvironment(TME),cancer stem cell(CSC)stemness and so on.With regard to tumor metabolism,the ubiquitination of some key proteins such as RagA,mTOR,PTEN,AKT,c-Myc and P53 significantly regulates the activity of the mTORC1,AMPK and PTEN-AKT signaling pathways.In addition,ubiquitination in the TLR,RLR and STING-dependent signaling pathways also modulates the TME.Moreover,the ubiquitination of core stem cell regulator triplets(Nanog,Oct4 and Sox2)and members of the Wnt and Hippo-YAP signaling pathways participates in the maintenance of CSC stemness.Based on the altered components,including the proteasome,E3 ligases,E1,E2 and deubiquitinases(DUBs),many molecular targeted drugs have been developed to combat cancer.Among them,small molecule inhibitors targeting the proteasome,such as bortezomib,carfilzomib,oprozomib and ixazomib,have achieved tangible success.In addition,MLN7243 and MLN4924(targeting the E1 enzyme),Leucettamol A and CC0651(targeting the E2 enzyme),nutlin and MI‐219(targeting the E3 enzyme),and compounds G5 and F6(targeting DUB activity)have also shown potential in preclinical cancer treatment.In this review,we summarize the latest progress in understanding the substrates for ubiquitination and their special functions in tumor metabolism regulation,TME mo展开更多
IAPs (inhibitors of apoptosis) are a family of proteins containing one or more characteristic BIR domains. These proteins have multiple biological activities that include binding and inhibiting caspases, regulating ce...IAPs (inhibitors of apoptosis) are a family of proteins containing one or more characteristic BIR domains. These proteins have multiple biological activities that include binding and inhibiting caspases, regulating cell cycle progression, and modulating receptor-mediated signal transduction. Our recent studies found the IAP family members XIAP and c-IAP1 are ubiquitinated and degraded in proteasomes in response to apoptotic stimuli in T cells, and their degradation appears to be important for T cells to commit to death. In addition to three BIR domains, each of these IAPs also contains a RING finger domain.We found this region confers ubiquitin protease ligase (E3) activity to IAPs, and is responsible for the auto-ubiquitination and degradation of IAPs after an apoptotic stimulus. Given the factthat IAPs can bind a variety of proteins, such as caspases and TRAFs, it will be of interest to characterize potential substrates of the E3 activity of IAPs and the effects of ubiquitination byIAPs on signal transduction, cell cycle, and apoptosis.展开更多
The NF-κB transcription factor is a central mediator of inflammatory and innate immune signaling pathways. Activation of NF-KB is achieved by K63-1inked polyubiquitination of key signaling molecules which recruit kin...The NF-κB transcription factor is a central mediator of inflammatory and innate immune signaling pathways. Activation of NF-KB is achieved by K63-1inked polyubiquitination of key signaling molecules which recruit kinase complexes that in turn activate the IKB kinase （IKK）. Ubiquitination is a highly dynamic process and is balanced by deubiquitinases that cleave polyubiquitin chains and terminate downstream signaling events. The A20 deubiquitinase is a critical negative regulator of NF-κB and inflammation, since A20-deficient mice develop uncontrolled and spontaneous multi-organ inflammation. Furthermore, specific polymorphisms in the A20 genomic locus predispose humans to autoimmune disease. Recent studies also indicate that A20 is an important tumor suppressor that is inactivated in B-cell lymphomas. Therefore, targeting A20 may form the basis of novel therapies for autoimmune disease and lymphomas.展开更多
Green plants on the earth have evolved intricate mechanisms to acclimatize to and utilize sunlight.In Arabidopsis,light signals are perceived by photoreceptors and transmitted through divergent but overlapping signali...Green plants on the earth have evolved intricate mechanisms to acclimatize to and utilize sunlight.In Arabidopsis,light signals are perceived by photoreceptors and transmitted through divergent but overlapping signaling networks to modulate plant photomorphogenic development.COP1(CONSTITUTIVE PHOTOMORPHOGENIC 1)was first cloned as a central repressor of photomorphogenesis in higher plants and has been extensively studied for over 30 years.It acts as a RING E3 ubiquitin ligase downstream of multiple photoreceptors to target key light-signaling regulators for degradation,primarily as part of large protein complexes.The mammalian counterpart of COP1 is a pluripotent regulator of tumorigenesis and metabolism.A great deal of information on COP1 has been derived from whole-genome sequencing and functional studies in lower green plants,which enables us to illustrate its evolutionary history.Here,we reviewthe current understanding about COP1,with a focus on the conservation and functional diversification of COP1 and its signaling partners in different taxonomic clades.展开更多
Protein post-translational modification （PTM） by ubiquitination has been observed during many aspects of plant growth, development, and stress responses. The ubiquitin-proteasome system precisely regulates phytohorm...Protein post-translational modification （PTM） by ubiquitination has been observed during many aspects of plant growth, development, and stress responses. The ubiquitin-proteasome system precisely regulates phytohormone signaling by affecting protein activity, localization, assembly, and interaction ability. Absci- sic acid （ABA） is a major phytohormone, and plays important roles in plants under normal or stressed growth conditions. The ABA signaling pathway is composed of phosphatases, kinases, transcription fac- tors, and membrane ion channels. It has been reported that multiple ABA signaling transducers are sub- jected to the regulations by ubiquitination. In particular, recent studies have identified different types of E3 ligases that mediate ubiquitination of ABA receptors in different cell compartments. This review focuses on modulation of these components by monoubiquitination or polyubiquitination that occurs in the plasma membrane, endomembranes, and from the cytosol to the nucleus; this implies the existence of retrograde and trafficking processes that are regulated by ubiquitination in ABA signaling. A number of single-unit E3 ligases, components of multi-subunit E3 ligases, E2s, and specific subunits of the 26S proteasome involved in ABA signal regulation are discussed. Dissecting the precise functions of ubiquitination in the ABA pathway may help us understand key factors in the signaling of other phytohormones regulated by ubiqui- tination and other types of PTMs.展开更多
文摘Protein degradation through the ubiquitin-proteasome system is the major pathway of non-lysosomal proteolysis of intracellular proteins. It plays important roles in a variety of fundamental cellular processes such as regulation of cell cycle progression, division, development and differentiation, apoptosis, cell trafficking, and modulation of the immune and inflammatory responses. The central element of this system is the covalent linkage of ubiquitin to targeted proteins, which are then recognized by the 26S proteasome, an adenosine triphosphate-dependent, multi-catalytic protease. Damaged, oxidized, or misfolded proteins as well as regulatory proteins that control many critical cellular functions are among the targets of this degradation process. Aberration of this system leads to the dysregulation of cellular homeostasis and the development of multiple diseases. In this review, we described the basic biochemistry and molecular biology of the ubiquitin-proteasome system, and its complex role in the development of inflammatory and autoimmune diseases. In addition, therapies and potential therapeutic targets related to the ubiquitin-proteasome system are discussed as well.
文摘Transforming growth factor β （TGFβ） controls cellular behavior in embryonic and adult tissues. TGFβ binding to serine/threonine kinase receptors on the plasma membrane activates Smad molecules and additional signaling proteins that together regulate gene expression. In this review, mechanisms and models that aim at explaining the coordination between several components of the signaling network downstream of TGFβ are presented. We discuss how the activity and duration of TGFβ receptor/Smad signaling can be regulated by post-translational modifications that affect the stability of key proteins in the pathway. We highlight finks between these mechanisms and human diseases, such as tissue fibrosis and cancer.
文摘The last 40 years have witnessed how p53 rose from a viral binding protein to a central factor in both stress responses and tumor suppression.The exquisite regulation of p53 functions is of vital importance for cell fate decisions.Among the multiple layers of mechanisms controlling p53 function,posttranslational modifications (PTMs) represent an efficient and precise way.Major p53 PTMs include phosphorylation,ubiquitination,acetylation,and methylation.Meanwhile,other PTMs like sumoylation,neddylation,O-GlcNAcylation,adenosine diphosphate (ADP)-ribosylation,hydroxylation,and p-hydroxybutyrylation are also shown to play various roles in p53 regulation.By independent action or interaction,PTMs affect p53 stability,conformation,localization,and binding partners.Deregulation of the PTM-related pathway is among the major causes of p53-associated developmental disorders or diseases,especially in cancers.This review focuses on the roles of different p53 modification types and shows how these modifications are orchestrated to produce various outcomes by modulating p53 activities or targeted to treat different diseases caused by p53 dysregulation.
文摘Transforming growth factor-β （TGF-β） members are key cytokines that control embryogenesis and tissue homeostasis via transmembrane TGF-β type II （TβR II） and type I （TβRI） and serine/threonine kinases receptors. Aberrant activation of TGF-β signaling leads to diseases, including cancer. In advanced cancer, the TGF-β/SMAD pathway can act as an oncogenic factor driving tumor cell invasion and metastasis, and thus is considered to be a therapeutic target. The activity of TGF-β/SMAD pathway is known to be regulated by ubiquitination at multiple levels. As ubiquitination is reversible, emerging studies have uncovered key roles for ubiquitin-removals on TGF-β signaling components by deubiquitinating enzymes （DUBs）. In this paper, we summarize the latest findings on the DUBs that control the activity of the TGF-β signaling pathway. The regula- tory roles of these DUBs as a driving force for cancer progression as well as their underlying working mech- anisms are also discussed.
文摘3-Hydroxy-3-methylglutaryl coenzyme A （HMG CoA） reductase produces mevalonate, an important intermediate in the synthesis of cholesterol and essential nonsterol isoprenoids. The reductase is subject to an exorbitant amount of feedback control through multiple mechanisms that are mediated by sterol and nonsterol end-products of mevalonate metabolism. Here, I will discuss recent advances that shed light on one mechanism for control of reductase, which involves rapid degradation of the enzyme. Accumulation of certain sterols triggers binding of reductase to endoplasmic reticulum （ER） membrane proteins called Insig-1 and Insig-2. Reductase-Insig binding results in recruitment of a membrane-associated ubiquitin ligase called gp78, which initiates ubiquitination of reductase. This ubiquitination is an obligatory reaction for recognition and degradation of reductase from ER membranes by cytosolic 26S proteasomes. Thus, sterol-accelerated degradation of reductase represents an example of how a general cellular process （ER-associated degradation） is used to control an important metabolic pathway （cholesterol synthesis）.
文摘Post-translational modification is central to protein stability and to the modulation of protein activity. Various types of protein modification, such as phosphorylation, methylation, acetylation, myristoylation, glycosylation, and ubiquitination, have been reported. Among them, ubiquitination distinguishes itself from others in that most of the ubiquitinated proteins are targeted to the 26S proteasome for degradation. The ubiquitin/26S proteasome system constitutes the major protein degradation pathway in the cell. In recent years, the importance of the ubiquitination machinery in the control of numerous eukaryotic cellular functions has been increasingly appreciated. Increasing number of E3 ubiquitin ligases and their substrates, including a variety of essential cellular regulators have been identified. Studies in the past several years have revealed that the ubiquitination system is important for a broad range of plant developmental processes and responses to abiotic and biotic stresses. This review discusses recent advances in the functional analysis of ubiquitination-associated proteins from plants and pathogens that play important roles in plant-microbe interactions.
基金supported by grants from the National Natural Science Foundation of China(Nos.31801177,81702659,31830053,31920103007,81625019)the Science Technology Commission of Shanghai Municipality(No.18410722000)+1 种基金the Shanghai Sailing Program(No.18YF1419500)the Fundamental Research Funds for the Central Universities(No.22120180043).
文摘Ubiquitination,an important type of protein posttranslational modification(PTM),plays a crucial role in controlling substrate degradation and subsequently mediates the“quantity”and“quality”of various proteins,serving to ensure cell homeostasis and guarantee life activities.The regulation of ubiquitination is multifaceted and works not only at the transcriptional and posttranslational levels(phosphorylation,acetylation,methylation,etc.)but also at the protein level(activators or repressors).When regulatory mechanisms are aberrant,the altered biological processes may subsequently induce serious human diseases,especially various types of cancer.In tumorigenesis,the altered biological processes involve tumor metabolism,the immunological tumor microenvironment(TME),cancer stem cell(CSC)stemness and so on.With regard to tumor metabolism,the ubiquitination of some key proteins such as RagA,mTOR,PTEN,AKT,c-Myc and P53 significantly regulates the activity of the mTORC1,AMPK and PTEN-AKT signaling pathways.In addition,ubiquitination in the TLR,RLR and STING-dependent signaling pathways also modulates the TME.Moreover,the ubiquitination of core stem cell regulator triplets(Nanog,Oct4 and Sox2)and members of the Wnt and Hippo-YAP signaling pathways participates in the maintenance of CSC stemness.Based on the altered components,including the proteasome,E3 ligases,E1,E2 and deubiquitinases(DUBs),many molecular targeted drugs have been developed to combat cancer.Among them,small molecule inhibitors targeting the proteasome,such as bortezomib,carfilzomib,oprozomib and ixazomib,have achieved tangible success.In addition,MLN7243 and MLN4924(targeting the E1 enzyme),Leucettamol A and CC0651(targeting the E2 enzyme),nutlin and MI‐219(targeting the E3 enzyme),and compounds G5 and F6(targeting DUB activity)have also shown potential in preclinical cancer treatment.In this review,we summarize the latest progress in understanding the substrates for ubiquitination and their special functions in tumor metabolism regulation,TME mo
基金supported by the National Natural Science Foundation of China(No.30771140)the Scientific Research Project of Educational Department of Henan ProvinceChina(No.13A310070)
文摘IAPs (inhibitors of apoptosis) are a family of proteins containing one or more characteristic BIR domains. These proteins have multiple biological activities that include binding and inhibiting caspases, regulating cell cycle progression, and modulating receptor-mediated signal transduction. Our recent studies found the IAP family members XIAP and c-IAP1 are ubiquitinated and degraded in proteasomes in response to apoptotic stimuli in T cells, and their degradation appears to be important for T cells to commit to death. In addition to three BIR domains, each of these IAPs also contains a RING finger domain.We found this region confers ubiquitin protease ligase (E3) activity to IAPs, and is responsible for the auto-ubiquitination and degradation of IAPs after an apoptotic stimulus. Given the factthat IAPs can bind a variety of proteins, such as caspases and TRAFs, it will be of interest to characterize potential substrates of the E3 activity of IAPs and the effects of ubiquitination byIAPs on signal transduction, cell cycle, and apoptosis.
文摘The NF-κB transcription factor is a central mediator of inflammatory and innate immune signaling pathways. Activation of NF-KB is achieved by K63-1inked polyubiquitination of key signaling molecules which recruit kinase complexes that in turn activate the IKB kinase （IKK）. Ubiquitination is a highly dynamic process and is balanced by deubiquitinases that cleave polyubiquitin chains and terminate downstream signaling events. The A20 deubiquitinase is a critical negative regulator of NF-κB and inflammation, since A20-deficient mice develop uncontrolled and spontaneous multi-organ inflammation. Furthermore, specific polymorphisms in the A20 genomic locus predispose humans to autoimmune disease. Recent studies also indicate that A20 is an important tumor suppressor that is inactivated in B-cell lymphomas. Therefore, targeting A20 may form the basis of novel therapies for autoimmune disease and lymphomas.
基金supported by grants from National Key R&D Program of China(2017YFA0503800)National Natural Science Foundation of China(31330048,31621001)+3 种基金Peking-Tsinghua Center for Life SciencesPeking UniversitySouthern University of Science and TechnologyXiamen University.
文摘Green plants on the earth have evolved intricate mechanisms to acclimatize to and utilize sunlight.In Arabidopsis,light signals are perceived by photoreceptors and transmitted through divergent but overlapping signaling networks to modulate plant photomorphogenic development.COP1(CONSTITUTIVE PHOTOMORPHOGENIC 1)was first cloned as a central repressor of photomorphogenesis in higher plants and has been extensively studied for over 30 years.It acts as a RING E3 ubiquitin ligase downstream of multiple photoreceptors to target key light-signaling regulators for degradation,primarily as part of large protein complexes.The mammalian counterpart of COP1 is a pluripotent regulator of tumorigenesis and metabolism.A great deal of information on COP1 has been derived from whole-genome sequencing and functional studies in lower green plants,which enables us to illustrate its evolutionary history.Here,we reviewthe current understanding about COP1,with a focus on the conservation and functional diversification of COP1 and its signaling partners in different taxonomic clades.
文摘Protein post-translational modification （PTM） by ubiquitination has been observed during many aspects of plant growth, development, and stress responses. The ubiquitin-proteasome system precisely regulates phytohormone signaling by affecting protein activity, localization, assembly, and interaction ability. Absci- sic acid （ABA） is a major phytohormone, and plays important roles in plants under normal or stressed growth conditions. The ABA signaling pathway is composed of phosphatases, kinases, transcription fac- tors, and membrane ion channels. It has been reported that multiple ABA signaling transducers are sub- jected to the regulations by ubiquitination. In particular, recent studies have identified different types of E3 ligases that mediate ubiquitination of ABA receptors in different cell compartments. This review focuses on modulation of these components by monoubiquitination or polyubiquitination that occurs in the plasma membrane, endomembranes, and from the cytosol to the nucleus; this implies the existence of retrograde and trafficking processes that are regulated by ubiquitination in ABA signaling. A number of single-unit E3 ligases, components of multi-subunit E3 ligases, E2s, and specific subunits of the 26S proteasome involved in ABA signal regulation are discussed. Dissecting the precise functions of ubiquitination in the ABA pathway may help us understand key factors in the signaling of other phytohormones regulated by ubiqui- tination and other types of PTMs.
