AIM To clarify the mechanisms involved in the critical endoplasmic reticulum(ER) stress initiating unfolded protein response pathway modified by melatonin.METHODS Hepatoma cells, Hep G2, were cultured in vitro. Flow c...AIM To clarify the mechanisms involved in the critical endoplasmic reticulum(ER) stress initiating unfolded protein response pathway modified by melatonin.METHODS Hepatoma cells, Hep G2, were cultured in vitro. Flow cytometry and TUNEL assay were used to measure Hep G2 cell apoptosis. Western blotting and quantitative reverse transcription-polymerase chain reaction methods were used to determine the protein and messenger RNA levels of ER stress and apoptosis related genes' expression, respectively. Tissue microarray construction from patients was verified by immunohistochemical analysis.RESULTS In the present study, we first identified that melatoninselectively blocked activating transcription factor 6(ATF-6) and then inhibited cyclooxygenase-2 (COX-2) expression, leading to enhanced liver cancer cell apoptosis under ER stress condition. Dramatically increased CCAAT-enhancer-binding protein homologous protein level, suppressed COX-2 and decreased Bcl-2/Bax ratio by melatonin or ATF-6 si RNA contributed the enhanced Hep G2 cell apoptosis under tunicamycin (an ER stress inducer) stimulation. In clinical hepatocellular carcinoma patients, the close relationship between ATF-6 and COX-2 was further confirmed.CONCLUSION These findings indicate that melatonin as a novel selective ATF-6 inhibitor can sensitize human hepatoma cells to ER stress inducing apoptosis.展开更多
Sperm of sea cucumber Apostichopus japonicus (Selenka) were quiescent in electrolyte NaCl solution and artificial seawater (ASW) and nonelectrolyte glucose and mannitol solutions when the osmolality was less than 200 ...Sperm of sea cucumber Apostichopus japonicus (Selenka) were quiescent in electrolyte NaCl solution and artificial seawater (ASW) and nonelectrolyte glucose and mannitol solutions when the osmolality was less than 200 mOsm kg-1. The sperm started to be motile as a result of increased osmolality, indicating an osmolality-dependent initiation of sperm motility in sea cucumber. After a brief incubation in hypotonic NaCl and glucose solutions with osmolalities of 200 and 400 mOsm kg-1, sperm lost partial motile ability. Sperm became immobilized when pH was 6.0 in NaCl, glucose and mannitol solutions, suggesting that an H+ release is involved in sperm activation. The decreased pH had no effect on the percentage of motile sperm in ASW, whereas it delayed the time period to reach the maximum motility (motilitymax). Extracellular Ca2+ in electrolyte solutions was not essential for motility stimulation but shortened the time of reaching motilitymax. When Ca2+ was mixed in nonelectrolyte solutions the sperm motility was completely suppressed. The K+ channel blocker, quinine, suppressed the sperm motility in electrolyte solution, showing a possible involvement of K+ transport in the process. High K+ concentration did not affect the sperm motility in NaCl solution, but decreased it in ASW and almost entirely suppressed it in nonelectrolyte solutions. The different effects of pH and K+ in ASW and NaCl solution indicate that external ions may also regulate sperm motility.展开更多
The paper summarizes the research progresses of electrical capacitance and electrical resistance assessing tree vigor and points out the development direction of the study. Researches show that electrical capacitance ...The paper summarizes the research progresses of electrical capacitance and electrical resistance assessing tree vigor and points out the development direction of the study. Researches show that electrical capacitance is related to the indexes of periodic growth rate of trees, foliar biomass and diameter of breast height, while electrical resistance has inverse relationships with the above indexes. Eiectrical capacitance and electrical resistance change when trees suffer environmental stress, insect pests or diseases. Especially, changes of electrical resistance are observed before symptom expression of some tree diseases, which can help to establish a certain disease potential hazard rating system. Mechanisms of electrical capacitance and resistance assessing tree vigor, especially in molecule level, still need to be studied and the application criteria of electrical resistance and capacitance need to be established.展开更多
基金grants from the National Natural Science Foundation of China,No.81572430 and No.81272739
文摘AIM To clarify the mechanisms involved in the critical endoplasmic reticulum(ER) stress initiating unfolded protein response pathway modified by melatonin.METHODS Hepatoma cells, Hep G2, were cultured in vitro. Flow cytometry and TUNEL assay were used to measure Hep G2 cell apoptosis. Western blotting and quantitative reverse transcription-polymerase chain reaction methods were used to determine the protein and messenger RNA levels of ER stress and apoptosis related genes' expression, respectively. Tissue microarray construction from patients was verified by immunohistochemical analysis.RESULTS In the present study, we first identified that melatoninselectively blocked activating transcription factor 6(ATF-6) and then inhibited cyclooxygenase-2 (COX-2) expression, leading to enhanced liver cancer cell apoptosis under ER stress condition. Dramatically increased CCAAT-enhancer-binding protein homologous protein level, suppressed COX-2 and decreased Bcl-2/Bax ratio by melatonin or ATF-6 si RNA contributed the enhanced Hep G2 cell apoptosis under tunicamycin (an ER stress inducer) stimulation. In clinical hepatocellular carcinoma patients, the close relationship between ATF-6 and COX-2 was further confirmed.CONCLUSION These findings indicate that melatonin as a novel selective ATF-6 inhibitor can sensitize human hepatoma cells to ER stress inducing apoptosis.
基金supported by an 863 High Technology Project (No. 2006AA10A411) from the Chinese Ministry of Science and Technologyan NSFC grant (No. 30571417)
文摘Sperm of sea cucumber Apostichopus japonicus (Selenka) were quiescent in electrolyte NaCl solution and artificial seawater (ASW) and nonelectrolyte glucose and mannitol solutions when the osmolality was less than 200 mOsm kg-1. The sperm started to be motile as a result of increased osmolality, indicating an osmolality-dependent initiation of sperm motility in sea cucumber. After a brief incubation in hypotonic NaCl and glucose solutions with osmolalities of 200 and 400 mOsm kg-1, sperm lost partial motile ability. Sperm became immobilized when pH was 6.0 in NaCl, glucose and mannitol solutions, suggesting that an H+ release is involved in sperm activation. The decreased pH had no effect on the percentage of motile sperm in ASW, whereas it delayed the time period to reach the maximum motility (motilitymax). Extracellular Ca2+ in electrolyte solutions was not essential for motility stimulation but shortened the time of reaching motilitymax. When Ca2+ was mixed in nonelectrolyte solutions the sperm motility was completely suppressed. The K+ channel blocker, quinine, suppressed the sperm motility in electrolyte solution, showing a possible involvement of K+ transport in the process. High K+ concentration did not affect the sperm motility in NaCl solution, but decreased it in ASW and almost entirely suppressed it in nonelectrolyte solutions. The different effects of pH and K+ in ASW and NaCl solution indicate that external ions may also regulate sperm motility.
基金Supported by the National Nature Science Foundation of China (grant No. 30471384 )
文摘The paper summarizes the research progresses of electrical capacitance and electrical resistance assessing tree vigor and points out the development direction of the study. Researches show that electrical capacitance is related to the indexes of periodic growth rate of trees, foliar biomass and diameter of breast height, while electrical resistance has inverse relationships with the above indexes. Eiectrical capacitance and electrical resistance change when trees suffer environmental stress, insect pests or diseases. Especially, changes of electrical resistance are observed before symptom expression of some tree diseases, which can help to establish a certain disease potential hazard rating system. Mechanisms of electrical capacitance and resistance assessing tree vigor, especially in molecule level, still need to be studied and the application criteria of electrical resistance and capacitance need to be established.
