Autophagy is essential for the maintenance of cellular homeostasis and its dysfunction has been linked to various diseases.Autophagy is a membrane driven process and tightly regulated by membrane-associated proteins.H...Autophagy is essential for the maintenance of cellular homeostasis and its dysfunction has been linked to various diseases.Autophagy is a membrane driven process and tightly regulated by membrane-associated proteins.Here,we summarized membrane lipid composition,and membrane-associated proteins relevant to autophagy from a spatiotemporal perspective.In particular,we focused on three important membrane remodeling processes in autophagy,lipid transfer for phagophore elongation,membrane scission for phago-phore closure,and autophagosome-lysosome membrane fusion.We discussed the significance of the discoveries in this field and possible avenues to follow for future studies.Finally,we summarized the membrane-associated biochemical techniques and assays used to study membrane properties,with a discussion of their applications in autophagy.展开更多
Many sources of stress cause accumulation of unfolded or misfolded proteins in endoplasmic reticulum(ER), which elicits the unfolded protein response(UPR) to either promote cell survival or programmed cell death depen...Many sources of stress cause accumulation of unfolded or misfolded proteins in endoplasmic reticulum(ER), which elicits the unfolded protein response(UPR) to either promote cell survival or programmed cell death depending on different developmental context or stress severity. The Arabidopsis membrane-associated transcription factor, b ZIP28, is the functional equivalent of mammalian ATF6, which relocates from the ER to the Golgi where it is proteolytically processed and released from the membrane to the nucleus to mediate the UPR. Although the canonical site-1 protease(S1P) cleavage site on the ER lumen-facing domain is well conserved between b ZIP28 and ATF6, the importance of S1 P cleavage on b ZIP28 has not been experimentally demonstrated. Here we provide genetic evidence that the RRIL573 site, but not the RVLM373 site, on the lumen-facing domain of bZ IP28 is critical for the biological function of b ZIP28 under ER stress condition. Further biochemistry and cell biology studies demonstrated that the RRIL573 site, but not the RVLM373 site, is required for proteolytic processing and nuclear relocation of b ZIP28 in response to ER stress. Our results reveal that S1 P cleavage site plays a pivotal role in activation and function of b ZIP28 during UPR in plants.展开更多
The seeds of barley Hordeum vulgare L. cv. Jian 4) were soaked with 0.1 mmol/L putrescine (Put) and 0.5 mmol/L spermidine (Spd), and then the seedlings were treated with 200 mmol/L NaCl. The growth rate (GR), dry matt...The seeds of barley Hordeum vulgare L. cv. Jian 4) were soaked with 0.1 mmol/L putrescine (Put) and 0.5 mmol/L spermidine (Spd), and then the seedlings were treated with 200 mmol/L NaCl. The growth rate (GR), dry matter accumulation, distribution of ions, the amount of polyamines (PAs) bound to tonoplast proteins as well as lipid composition and the activity of tonoplast vesicles isolated from roots were investigated. The results showed that soaking with Put or Spd could retard salt injury, promote GR and dry matter accumulation, and increase K+/Na+ in the roots. Compared with NaCl_treated plants, phospholipid content in root tonoplast rose by soaking with Put and Spd, while the level of galactose in lipids was decreased. Moreover, the ratio in noncovalently conjugated PA contents of (Spd+PAx (an unknown PA)) to (Put+Dap (diaminopropane)), and the total contents of covalently and noncovalently conjugated PAs were all increased. Statistical analysis indicated that the ratio of (Spd+PAx) to (Put+Dap) was significantly and positively correlated with the activities of membrane associated enzymes H+_ATPase and H+_PPase.展开更多
A variety of glycosylphosphatidylinositol （GPI）-linked proteins are acquired on spermatozoa from epididymal luminal fluids （ELF） during sperm maturation. These proteins serve roles in immunoprotection and in key s...A variety of glycosylphosphatidylinositol （GPI）-linked proteins are acquired on spermatozoa from epididymal luminal fluids （ELF） during sperm maturation. These proteins serve roles in immunoprotection and in key steps of fertilization such as capacitation, acrosomal exocytosis and sperm-egg interactions. Their acquisition on sperm cells is mediated both by membrane vesicles （epididymosomes, EP） which were first reported to dock on the sperm surface, and by lipid carriers which facilitate the transfer of proteins associated with the membrane-free fraction of ELF. While the nonvesicular fraction is more efficient, both pathways are dependent on hydrophobic interactions between the GPI-anchor and the external lipid layer of the sperm surface. More recently proteomic and hypothesis-driven studies have shown that EP from several mammals carry transmembrane （TM） proteins, including plasma membrane Ca^2＋-ATPase 4 （PMCA4）. Synthesized in the testis, PMCA4 is an essential protein and the major Ca^2＋ efflux pump in murine spermatozoa. Delivery of PMCA4 to spermatozoa from bovine and mouse EP during epididymal maturation and in vitro suggests that the docking of EP on the sperm surface precedes fusion, and experimental evidence supports a fusogenic mechanism for TM proteins. Fusion is facilitated by CD9, which generates fusion-competent sites on membranes. On the basis of knowledge of PMCA4＇s interacting partners a number of TM and membrane-associated proteins have been identified or are predicted to be present, in the epididymosomal cargo deliverable to spermatozoa. These Ca^2＋-dependent proteins, undetected in proteomic studies, play essential roles in sperm motility and fertility, and their detection highlights the usefulness of the hypothesis-driven approach.展开更多
Streptococcus equi ssp. zooepidemicus （S. zooepidemicus） is a zoonotic pathogen with worldwide distribution. Lacking suitable vaccine and virulent maker is still bottleneck to control this infection. An immunoproteo...Streptococcus equi ssp. zooepidemicus （S. zooepidemicus） is a zoonotic pathogen with worldwide distribution. Lacking suitable vaccine and virulent maker is still bottleneck to control this infection. An immunoproteomic approach has been used to screen the membrane-associated and cell wall-associated proteins of S. zooepidemicus isolate in China CY to discover vaccine candidate antigens and therapeutic agents. Finally, 11 membrane-associated proteins, and 13 cell wall-associated proteins were successfully identified. BLAST （www.sanger.ac.uk） results also indicated that nucleotide sequences of majority identified proteins shared high homology （60%） with S. zooepidemicus, except for AC1-3, AC5, AC8, and AC13. Moreover, genes for 7 of the identified proteins were detected from CY; compared with ST171, 3 of them （AM1, AM8 and AC11） were only found in virulent strains （CY）. All of the proteins identified in this study remain not to be reported in S. zooepidemicus. Some of the proteins serve a vital role in the immune system and reproduction of host species according to available data, while the functions of the rest were seldom researched.展开更多
基金grants from NSFC(91754205,91957204,31771523,31870830 and 31801170)MOST(2019YFA0508602)+2 种基金Shanghai Municipal Science and Technology Project(20JC1411100)Program of Shanghai Academic/Technology Research Leader(19XD1402200)innovative research team of high-level local universities in Shanghai.
文摘Autophagy is essential for the maintenance of cellular homeostasis and its dysfunction has been linked to various diseases.Autophagy is a membrane driven process and tightly regulated by membrane-associated proteins.Here,we summarized membrane lipid composition,and membrane-associated proteins relevant to autophagy from a spatiotemporal perspective.In particular,we focused on three important membrane remodeling processes in autophagy,lipid transfer for phagophore elongation,membrane scission for phago-phore closure,and autophagosome-lysosome membrane fusion.We discussed the significance of the discoveries in this field and possible avenues to follow for future studies.Finally,we summarized the membrane-associated biochemical techniques and assays used to study membrane properties,with a discussion of their applications in autophagy.
基金supported by grants from the National Basic Research Program of China(973 Program,2012CB910500)the National Natural Science Foundation of China(31171157,31222008)the Specialized Research Fund for the Doctoral Program of Higher Education(20130071110011)
文摘Many sources of stress cause accumulation of unfolded or misfolded proteins in endoplasmic reticulum(ER), which elicits the unfolded protein response(UPR) to either promote cell survival or programmed cell death depending on different developmental context or stress severity. The Arabidopsis membrane-associated transcription factor, b ZIP28, is the functional equivalent of mammalian ATF6, which relocates from the ER to the Golgi where it is proteolytically processed and released from the membrane to the nucleus to mediate the UPR. Although the canonical site-1 protease(S1P) cleavage site on the ER lumen-facing domain is well conserved between b ZIP28 and ATF6, the importance of S1 P cleavage on b ZIP28 has not been experimentally demonstrated. Here we provide genetic evidence that the RRIL573 site, but not the RVLM373 site, on the lumen-facing domain of bZ IP28 is critical for the biological function of b ZIP28 under ER stress condition. Further biochemistry and cell biology studies demonstrated that the RRIL573 site, but not the RVLM373 site, is required for proteolytic processing and nuclear relocation of b ZIP28 in response to ER stress. Our results reveal that S1 P cleavage site plays a pivotal role in activation and function of b ZIP28 during UPR in plants.
文摘The seeds of barley Hordeum vulgare L. cv. Jian 4) were soaked with 0.1 mmol/L putrescine (Put) and 0.5 mmol/L spermidine (Spd), and then the seedlings were treated with 200 mmol/L NaCl. The growth rate (GR), dry matter accumulation, distribution of ions, the amount of polyamines (PAs) bound to tonoplast proteins as well as lipid composition and the activity of tonoplast vesicles isolated from roots were investigated. The results showed that soaking with Put or Spd could retard salt injury, promote GR and dry matter accumulation, and increase K+/Na+ in the roots. Compared with NaCl_treated plants, phospholipid content in root tonoplast rose by soaking with Put and Spd, while the level of galactose in lipids was decreased. Moreover, the ratio in noncovalently conjugated PA contents of (Spd+PAx (an unknown PA)) to (Put+Dap (diaminopropane)), and the total contents of covalently and noncovalently conjugated PAs were all increased. Statistical analysis indicated that the ratio of (Spd+PAx) to (Put+Dap) was significantly and positively correlated with the activities of membrane associated enzymes H+_ATPase and H+_PPase.
文摘A variety of glycosylphosphatidylinositol （GPI）-linked proteins are acquired on spermatozoa from epididymal luminal fluids （ELF） during sperm maturation. These proteins serve roles in immunoprotection and in key steps of fertilization such as capacitation, acrosomal exocytosis and sperm-egg interactions. Their acquisition on sperm cells is mediated both by membrane vesicles （epididymosomes, EP） which were first reported to dock on the sperm surface, and by lipid carriers which facilitate the transfer of proteins associated with the membrane-free fraction of ELF. While the nonvesicular fraction is more efficient, both pathways are dependent on hydrophobic interactions between the GPI-anchor and the external lipid layer of the sperm surface. More recently proteomic and hypothesis-driven studies have shown that EP from several mammals carry transmembrane （TM） proteins, including plasma membrane Ca^2＋-ATPase 4 （PMCA4）. Synthesized in the testis, PMCA4 is an essential protein and the major Ca^2＋ efflux pump in murine spermatozoa. Delivery of PMCA4 to spermatozoa from bovine and mouse EP during epididymal maturation and in vitro suggests that the docking of EP on the sperm surface precedes fusion, and experimental evidence supports a fusogenic mechanism for TM proteins. Fusion is facilitated by CD9, which generates fusion-competent sites on membranes. On the basis of knowledge of PMCA4＇s interacting partners a number of TM and membrane-associated proteins have been identified or are predicted to be present, in the epididymosomal cargo deliverable to spermatozoa. These Ca^2＋-dependent proteins, undetected in proteomic studies, play essential roles in sperm motility and fertility, and their detection highlights the usefulness of the hypothesis-driven approach.
基金supported by the Program for New Century Excellent Talents (NCET) at the University of China (NCET-08-0794)the Key Technology R&D Program of Jiansu Province, China (BE2009388)+1 种基金the Fundamental Research Funds for the Central Universities, China (KYT 201003)the Project Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions, China
文摘Streptococcus equi ssp. zooepidemicus （S. zooepidemicus） is a zoonotic pathogen with worldwide distribution. Lacking suitable vaccine and virulent maker is still bottleneck to control this infection. An immunoproteomic approach has been used to screen the membrane-associated and cell wall-associated proteins of S. zooepidemicus isolate in China CY to discover vaccine candidate antigens and therapeutic agents. Finally, 11 membrane-associated proteins, and 13 cell wall-associated proteins were successfully identified. BLAST （www.sanger.ac.uk） results also indicated that nucleotide sequences of majority identified proteins shared high homology （60%） with S. zooepidemicus, except for AC1-3, AC5, AC8, and AC13. Moreover, genes for 7 of the identified proteins were detected from CY; compared with ST171, 3 of them （AM1, AM8 and AC11） were only found in virulent strains （CY）. All of the proteins identified in this study remain not to be reported in S. zooepidemicus. Some of the proteins serve a vital role in the immune system and reproduction of host species according to available data, while the functions of the rest were seldom researched.
