Antigen cross-presentation in dendritic cells is a complex intracellular membrane transport process, but the underlying molecular mechanisms remain to be thoroughly investigated.
Aberration of lipid storage in lipid droplets (LD) has been linked with the development and progression of several common metabolic diseases including obesity, type II diabetes,
Abnormal intracellular accumulation or transport of lipids contributes greatly to the pathogenesis of human diseases. In the liver, excess accumulation of triacylglycerol （TG） leads to fatty liver disease encompassi...Abnormal intracellular accumulation or transport of lipids contributes greatly to the pathogenesis of human diseases. In the liver, excess accumulation of triacylglycerol （TG） leads to fatty liver disease encompassing steatosis, steatohepatitis and fibrosis. This places individuals at risk of developing cirrhosis, hepatocellular carcinoma or hepatic decompensation and also contributes to the emergence of insulin resistance and dyslipidemias affecting many other organs. Excessive accumulation of TG in adipose tissue contributes to insulin resistance as well as to the release of cytokines attracting leucocytes leading to a pro-inflammatory state. Pathological accumulation of cholesteryl ester （CE） in macrophages in the arterial wall is the progenitor of atherosclerotic plaques and heart disease. Overconsumption of dietary fat, cholesterol and carbohydrates explains why these diseases are on the increase yet offers few clues for how to prevent or treat individuals. Dietary regimes have proven futile and barfing surgery, no realistic alternatives are at hand as effective drugs are few and not without side effects. Overweight and obesity-related diseases are no longer restricted to the developed world and as such, constitute a global problem. Development of new drugs and treatment strategies are a priority yet requires as a first step, elucidation of the molecular pathophysiology underlying each associated disease state. The lipid droplet （LD）, an up to now over- looked intracellular organelle, appears at the heart of each pathophysiology linking key regulatory and metabolic processes as well as constituting the site of storage of both TGs and CEs. As the molecular machinery and mechanisms of LDs of each cell type are being elucidated, regulatory proteins used to control various cellular processes are emerging. Of these and the subject of this review, small GTPases belonging to the Rab protein family appear as important molecular switches used in the regulation of the intracellular trafficking and storage of lipids.展开更多
Small GTPase is a kind of GTP-binding protein commonly found in eukaryotic cells.It plays an important role in cytoskeletal reorganization,cell polarity,cell cycle progression,gene expression and many other significan...Small GTPase is a kind of GTP-binding protein commonly found in eukaryotic cells.It plays an important role in cytoskeletal reorganization,cell polarity,cell cycle progression,gene expression and many other significant events in cells,such as the interaction with foreign particles.Therefore,it is of great scientific significance to understand the biological properties of small GTPases as well as the GTPase-nano interplay,since more and more nanomedicine are supposed to be used in biomedical field.However,there is no review in this aspect.This review summarizes the small GTPases in terms of the structure,biological function and its interaction with nanoparticles.We briefly introduced the various nanoparticles such as gold/silver nanoparticles,SWCNT,polymeric micelles and other nano delivery systems that interacted with different GTPases.These current nanoparticles exhibited different pharmacological effect modes and various target design concepts in the small GTPases study.This will help to elucidate the conclusion that the therapeutic strategy targeting small GTPases might be a new research direction.It is believed that the in-depth study on the functional mechanism of GTPases can provide insights for the design and study of nanomedicines.展开更多
Mammalian and plant Rabl and Rab2 are small GTPases that regulate vesicle trafficking in the endoplasmic reticulum （ER） to Golgi compartments. Little is known about their functional diversification or potential inte...Mammalian and plant Rabl and Rab2 are small GTPases that regulate vesicle trafficking in the endoplasmic reticulum （ER） to Golgi compartments. Little is known about their functional diversification or potential interaction. We cloned sugarcane （Saccharum officinarum L.） Rab1A and Rab2A genes and studied their functional differences by expression and complementation experiments. We found differential expression of the two genes during sugarcane leaf development： SoRab2A expression declined from the dividing base to the maturing tip of the growing leaves, whereas SoRab1A was constitutively expressed, suggesting that SoRab2A is required for cell division and expansion and SoRablA is required for cells at all developmental stages. We used a yeast temperature sensitive ypt1-A 136D mutant strain to further investigate these shared and unique functions. Yptl is a small GTPase that regulates vesicle transport in the same cellular location as Rabl and Rab2. Neither SoRab1A nor SoRab2A alone could restore the growth of the mutant at restrictive temperatures when SoRab1A and SoRab2A were transformed separately. However, SoRab1A transformants maintained normal morphology and viability at non-permissive temperature, and resumed growth when returned to permissive temperature, whereas SoRab2A transformants died at non-permissive temperature, suggesting that SoRablA function is required for a cell＇s viability. Mutant growth was fully restored when SoRab1A and SoRab2A were co-transformed, indicating that SoRablA and SoRab2A complement each other and they both are needed to restore the function of ypt1-A136D. These results demonstrate that SoRab1A and SoRab2A serve distinct but overlapping functions, mostly by regulating the transportation of different sets of proteins.展开更多
The retromer complex,composed of the cargo-selective complex(CSC)Vps35-Vps29-Vps26 in complex with the sorting nexin dimer Vps5-Vps17,mediates the sorting and retrograde transport of cargo proteins from the endosomes ...The retromer complex,composed of the cargo-selective complex(CSC)Vps35-Vps29-Vps26 in complex with the sorting nexin dimer Vps5-Vps17,mediates the sorting and retrograde transport of cargo proteins from the endosomes to the trans-Golgi network in eukaryotic cells.Rab proteins belong to the Ras superfamily of small GTPases and regulate many trafficking events including vesicle formation,budding,transport,tethering,docking and fusion with target membranes.Herein,we investigated the potential functional relationship between the retromer complex and the 11 Rab proteins that exist in Fusarium graminearum using genetic and high-resolution laser confocal microscopic approaches.We found that only FgRab5(FgRab5A and FgRab5B)and FgRab7 associate with the retromer complex.Both FgVps35-GFP and FgVps17-GFP are mis-localized and appear diffused in the cytoplasm ofΔFgrab5A,ΔFgrab5B andΔFgrab7 mutants as compared to their punctate localization within the endosomes of the wild-type.FgRab7 and FgRab5B were found to co-localize with the retromer on endosomal membranes.Most strikingly,we found that these three Rab GTPases are indispensable for endosome biogenesis as both early and late endosomes could not be detected in the cells of the mutants after FM4-64 staining of the cells,while they were very clearly seen in the wild-type PH-1.Furthermore,FgRab7 was found to recruit FgVps35 but not FgVps17 to the endosomal membranes,whereas FgRab5B recruits both FgVps35 and FgVps17 to the membranes.Thus,we conclude that the Rab proteins FgRab5A,FgRab5B and FgRab7 play critical roles in the biogenesis of endosomes and in regulating retromer-mediated trafficking in F.graminearum.展开更多
Collagens are large secreted trimeric proteins making up most of the animal extracellular matrix.Secretion of collagen has been a focus of interest for cell biologists in recent years because collagen trimers are too ...Collagens are large secreted trimeric proteins making up most of the animal extracellular matrix.Secretion of collagen has been a focus of interest for cell biologists in recent years because collagen trimers are too large and rigid to fit into the COPII vesicles mediating transport from the endoplasmic reticulum（ER） to the Golgi. Collagen-specific mechanisms to create enlarged ER-to-Golgi transport carriers have been postulated, including cargo loading by conserved ER exit site（ERES） protein Tango1.Here, we report an RNAi screening for genes involved in collagen secretion in Drosophila. In this screening, we examined distribution of GFP-tagged Collagen IV in live animals and found 88 gene hits for which the knockdown produced intracellular accumulation of Collagen IV in the fat body, the main source of matrix proteins in the larva. Among these hits, only two affected collagen secretion specifically：PH4 a EFB and Plod, encoding enzymes known to mediate posttranslational modification of collagen in the ER. Every other intracellular accumulation hit affected general secretion, consistent with the notion that secretion of collagen does not use a specific mode of vesicular transport, but the general secretory pathway. Included in our hits are many known players in the eukaryotic secretory machinery, like COPII and COPI components, SNAREs and Rab-GTPase regulators. Our further analysis of the involvement of Rab-GTPases in secretion shows that Rab1, Rab2 and Rab X3, are all required at ERES, each of them differentially affecting ERES morphology. Abolishing activity of all three by Rep knockdown, in contrast,led to uncoupling of ERES and Golgi. We additionally present a characterization of a screening hit we named trabuco（tbc）, encoding an ERES-localized TBC domain-containing Rab-GAP. Finally, we discuss the success of our screening in identifying secretory pathway genes in comparison to two previous secretion screenings in Drosophila S2 cells.展开更多
A root hair is a polarly elongated single-celled structure that derives from a root epidermal cell and func-tions in uptake of water and nutrients from the surrounding environment.Previous reports have demon-strated t...A root hair is a polarly elongated single-celled structure that derives from a root epidermal cell and func-tions in uptake of water and nutrients from the surrounding environment.Previous reports have demon-strated that short periods of high pH inhibit root hair extension;but the effects of long-term high-pH treat-ment on root hair growth are still unclear.Here,we report that the duration of root hair elongation is signicantly prolonged with increasing external pH,which counteracts the effect of decreasing root hair elongation rate and ultimately produces longer root hairs,whereas loss of actin-depolymerizing factor 8 and 11(ADF8/11)function causes shortening of root hair length at high pH(pH 7.4).Accumulation of ADF8/11 at the tips of root hairs is inhibited by high pH,and increasing environmental pH affects the actinlament(F-actin)meshwork at the root hair tip.At high pH,the tip-focused F-actin meshwork is absent in root hairs of the adf8/11 mutant,actinlaments are disordered at the adf8/11 root hair tips,and actin turn-over is attenuated.Secretory and recycling vesicles do not aggregate in the apical region of adf8/11 root hairs at high pH.Together,our results suggest that,under long-term exposure to high extracellular pH,ADF8/11 may establish and maintain the tip-focused F-actin meshwork to regulate polar trafcking of secretory/recycling vesicles at the root hair tips,thereby promoting root hair elongation.展开更多
Exosomes carry and transmit signaling molecules used for intercellular communication.The generation and secretion of exosomes is a multistep interlocking process that allows simultaneous control of multiple regulatory...Exosomes carry and transmit signaling molecules used for intercellular communication.The generation and secretion of exosomes is a multistep interlocking process that allows simultaneous control of multiple regulatory sites.Protein molecules,mainly RAB GTPases,cytoskeletal proteins and soluble N-ethylmaleimide-sensitive fusion attachment protein receptor(SNARE),are specifically regulated in response to pathological conditions such as altered cellular microenvironment,stimulation by pathogenic factors,or gene mutation.This interferes with the smooth functioning of endocytosis,translocation,degradation,docking and fusion processes,leading to changes in the secretion of exosomes.Large numbers of secreted exosomes are disseminated by the flow of body fluids and absorbed by the recipient cells.By transmitting characteristic functional proteins and genetic information produced under disease conditions,exosomes can change the physiological state of the recipient cells and their microenvironment.The microenvironment,in turn,affects the occurrence and development of disease.Therefore,this review will discuss the mechanism by which exosome secretion is regulated in cells following the formation of mature secretory multivesicular bodies(MVBs).The overall aim is to find ways to eliminate disease-derived exosomes at their source,thereby providing an important new basis for the clinical treatment of disease.展开更多
文摘Antigen cross-presentation in dendritic cells is a complex intracellular membrane transport process, but the underlying molecular mechanisms remain to be thoroughly investigated.
文摘Aberration of lipid storage in lipid droplets (LD) has been linked with the development and progression of several common metabolic diseases including obesity, type II diabetes,
文摘Abnormal intracellular accumulation or transport of lipids contributes greatly to the pathogenesis of human diseases. In the liver, excess accumulation of triacylglycerol （TG） leads to fatty liver disease encompassing steatosis, steatohepatitis and fibrosis. This places individuals at risk of developing cirrhosis, hepatocellular carcinoma or hepatic decompensation and also contributes to the emergence of insulin resistance and dyslipidemias affecting many other organs. Excessive accumulation of TG in adipose tissue contributes to insulin resistance as well as to the release of cytokines attracting leucocytes leading to a pro-inflammatory state. Pathological accumulation of cholesteryl ester （CE） in macrophages in the arterial wall is the progenitor of atherosclerotic plaques and heart disease. Overconsumption of dietary fat, cholesterol and carbohydrates explains why these diseases are on the increase yet offers few clues for how to prevent or treat individuals. Dietary regimes have proven futile and barfing surgery, no realistic alternatives are at hand as effective drugs are few and not without side effects. Overweight and obesity-related diseases are no longer restricted to the developed world and as such, constitute a global problem. Development of new drugs and treatment strategies are a priority yet requires as a first step, elucidation of the molecular pathophysiology underlying each associated disease state. The lipid droplet （LD）, an up to now over- looked intracellular organelle, appears at the heart of each pathophysiology linking key regulatory and metabolic processes as well as constituting the site of storage of both TGs and CEs. As the molecular machinery and mechanisms of LDs of each cell type are being elucidated, regulatory proteins used to control various cellular processes are emerging. Of these and the subject of this review, small GTPases belonging to the Rab protein family appear as important molecular switches used in the regulation of the intracellular trafficking and storage of lipids.
基金supported by the National Natural Science Foundation of China[81690264]the National Basic Research Program of China[2015CB932100,2017YFA0205600]the Innovation Team of the Ministry of Education[BMU20110263]。
文摘Small GTPase is a kind of GTP-binding protein commonly found in eukaryotic cells.It plays an important role in cytoskeletal reorganization,cell polarity,cell cycle progression,gene expression and many other significant events in cells,such as the interaction with foreign particles.Therefore,it is of great scientific significance to understand the biological properties of small GTPases as well as the GTPase-nano interplay,since more and more nanomedicine are supposed to be used in biomedical field.However,there is no review in this aspect.This review summarizes the small GTPases in terms of the structure,biological function and its interaction with nanoparticles.We briefly introduced the various nanoparticles such as gold/silver nanoparticles,SWCNT,polymeric micelles and other nano delivery systems that interacted with different GTPases.These current nanoparticles exhibited different pharmacological effect modes and various target design concepts in the small GTPases study.This will help to elucidate the conclusion that the therapeutic strategy targeting small GTPases might be a new research direction.It is believed that the in-depth study on the functional mechanism of GTPases can provide insights for the design and study of nanomedicines.
文摘Mammalian and plant Rabl and Rab2 are small GTPases that regulate vesicle trafficking in the endoplasmic reticulum （ER） to Golgi compartments. Little is known about their functional diversification or potential interaction. We cloned sugarcane （Saccharum officinarum L.） Rab1A and Rab2A genes and studied their functional differences by expression and complementation experiments. We found differential expression of the two genes during sugarcane leaf development： SoRab2A expression declined from the dividing base to the maturing tip of the growing leaves, whereas SoRab1A was constitutively expressed, suggesting that SoRab2A is required for cell division and expansion and SoRablA is required for cells at all developmental stages. We used a yeast temperature sensitive ypt1-A 136D mutant strain to further investigate these shared and unique functions. Yptl is a small GTPase that regulates vesicle transport in the same cellular location as Rabl and Rab2. Neither SoRab1A nor SoRab2A alone could restore the growth of the mutant at restrictive temperatures when SoRab1A and SoRab2A were transformed separately. However, SoRab1A transformants maintained normal morphology and viability at non-permissive temperature, and resumed growth when returned to permissive temperature, whereas SoRab2A transformants died at non-permissive temperature, suggesting that SoRablA function is required for a cell＇s viability. Mutant growth was fully restored when SoRab1A and SoRab2A were co-transformed, indicating that SoRablA and SoRab2A complement each other and they both are needed to restore the function of ypt1-A136D. These results demonstrate that SoRab1A and SoRab2A serve distinct but overlapping functions, mostly by regulating the transportation of different sets of proteins.
基金supported by grants from the National Natural Science Foundation of China(31772106)and the Natural Science Foundation of Fujian Province(2021J06015).The funders had no role in the study design,data collection and analysis,decision to publish,or preparation of the manuscript.
文摘The retromer complex,composed of the cargo-selective complex(CSC)Vps35-Vps29-Vps26 in complex with the sorting nexin dimer Vps5-Vps17,mediates the sorting and retrograde transport of cargo proteins from the endosomes to the trans-Golgi network in eukaryotic cells.Rab proteins belong to the Ras superfamily of small GTPases and regulate many trafficking events including vesicle formation,budding,transport,tethering,docking and fusion with target membranes.Herein,we investigated the potential functional relationship between the retromer complex and the 11 Rab proteins that exist in Fusarium graminearum using genetic and high-resolution laser confocal microscopic approaches.We found that only FgRab5(FgRab5A and FgRab5B)and FgRab7 associate with the retromer complex.Both FgVps35-GFP and FgVps17-GFP are mis-localized and appear diffused in the cytoplasm ofΔFgrab5A,ΔFgrab5B andΔFgrab7 mutants as compared to their punctate localization within the endosomes of the wild-type.FgRab7 and FgRab5B were found to co-localize with the retromer on endosomal membranes.Most strikingly,we found that these three Rab GTPases are indispensable for endosome biogenesis as both early and late endosomes could not be detected in the cells of the mutants after FM4-64 staining of the cells,while they were very clearly seen in the wild-type PH-1.Furthermore,FgRab7 was found to recruit FgVps35 but not FgVps17 to the endosomal membranes,whereas FgRab5B recruits both FgVps35 and FgVps17 to the membranes.Thus,we conclude that the Rab proteins FgRab5A,FgRab5B and FgRab7 play critical roles in the biogenesis of endosomes and in regulating retromer-mediated trafficking in F.graminearum.
基金funded by grants from the Natural Science Foundation of China (Nos.31771600 and 31750410689)Tsinghua Initiative Program (No.20131089281)a 1000 Talents award,all to J.C.P.-P
文摘Collagens are large secreted trimeric proteins making up most of the animal extracellular matrix.Secretion of collagen has been a focus of interest for cell biologists in recent years because collagen trimers are too large and rigid to fit into the COPII vesicles mediating transport from the endoplasmic reticulum（ER） to the Golgi. Collagen-specific mechanisms to create enlarged ER-to-Golgi transport carriers have been postulated, including cargo loading by conserved ER exit site（ERES） protein Tango1.Here, we report an RNAi screening for genes involved in collagen secretion in Drosophila. In this screening, we examined distribution of GFP-tagged Collagen IV in live animals and found 88 gene hits for which the knockdown produced intracellular accumulation of Collagen IV in the fat body, the main source of matrix proteins in the larva. Among these hits, only two affected collagen secretion specifically：PH4 a EFB and Plod, encoding enzymes known to mediate posttranslational modification of collagen in the ER. Every other intracellular accumulation hit affected general secretion, consistent with the notion that secretion of collagen does not use a specific mode of vesicular transport, but the general secretory pathway. Included in our hits are many known players in the eukaryotic secretory machinery, like COPII and COPI components, SNAREs and Rab-GTPase regulators. Our further analysis of the involvement of Rab-GTPases in secretion shows that Rab1, Rab2 and Rab X3, are all required at ERES, each of them differentially affecting ERES morphology. Abolishing activity of all three by Rep knockdown, in contrast,led to uncoupling of ERES and Golgi. We additionally present a characterization of a screening hit we named trabuco（tbc）, encoding an ERES-localized TBC domain-containing Rab-GAP. Finally, we discuss the success of our screening in identifying secretory pathway genes in comparison to two previous secretion screenings in Drosophila S2 cells.
基金supported by the National Natural Science Foundation of China (grants 31970195,31700161,32170331,32170330,and 6232300303)Hainan Yazhou Bay Seed Lab grant B23YQ1510,China Postdoctoral Science Foundation grant 2022M720058the Fundamental Research Funds for the Central Universities grants lzujbky-2022-ey06,lzujbky-2023-I02 and lzuibky-2023-pd10.
文摘A root hair is a polarly elongated single-celled structure that derives from a root epidermal cell and func-tions in uptake of water and nutrients from the surrounding environment.Previous reports have demon-strated that short periods of high pH inhibit root hair extension;but the effects of long-term high-pH treat-ment on root hair growth are still unclear.Here,we report that the duration of root hair elongation is signicantly prolonged with increasing external pH,which counteracts the effect of decreasing root hair elongation rate and ultimately produces longer root hairs,whereas loss of actin-depolymerizing factor 8 and 11(ADF8/11)function causes shortening of root hair length at high pH(pH 7.4).Accumulation of ADF8/11 at the tips of root hairs is inhibited by high pH,and increasing environmental pH affects the actinlament(F-actin)meshwork at the root hair tip.At high pH,the tip-focused F-actin meshwork is absent in root hairs of the adf8/11 mutant,actinlaments are disordered at the adf8/11 root hair tips,and actin turn-over is attenuated.Secretory and recycling vesicles do not aggregate in the apical region of adf8/11 root hairs at high pH.Together,our results suggest that,under long-term exposure to high extracellular pH,ADF8/11 may establish and maintain the tip-focused F-actin meshwork to regulate polar trafcking of secretory/recycling vesicles at the root hair tips,thereby promoting root hair elongation.
基金supported by grants from Natural Science Foundation of Jiangsu Province,China(No.BK20211105)the Key Research and Development Plan of Jiangsu Province,China(No.BE2019692)+2 种基金the Health Project of Jiangsu Province,China(No.H2019072)the Social Development Foundation of Nantong City,China(No.MS22020005,JCZ21061,MSZ20076 and JCZ20065)the Postgraduate Research&Practice Innovation Program of Jiangsu Province,China(No.KYCX20_2673,KYCX20_2681 and KYCX21_3112).
文摘Exosomes carry and transmit signaling molecules used for intercellular communication.The generation and secretion of exosomes is a multistep interlocking process that allows simultaneous control of multiple regulatory sites.Protein molecules,mainly RAB GTPases,cytoskeletal proteins and soluble N-ethylmaleimide-sensitive fusion attachment protein receptor(SNARE),are specifically regulated in response to pathological conditions such as altered cellular microenvironment,stimulation by pathogenic factors,or gene mutation.This interferes with the smooth functioning of endocytosis,translocation,degradation,docking and fusion processes,leading to changes in the secretion of exosomes.Large numbers of secreted exosomes are disseminated by the flow of body fluids and absorbed by the recipient cells.By transmitting characteristic functional proteins and genetic information produced under disease conditions,exosomes can change the physiological state of the recipient cells and their microenvironment.The microenvironment,in turn,affects the occurrence and development of disease.Therefore,this review will discuss the mechanism by which exosome secretion is regulated in cells following the formation of mature secretory multivesicular bodies(MVBs).The overall aim is to find ways to eliminate disease-derived exosomes at their source,thereby providing an important new basis for the clinical treatment of disease.
