Alkylation of diethyl 3 oxoglutarate monoanion by 4 bromobutene to produce enone diester 3, subsequent alkylation of 3 with 4 bromo 1 butene using K 2CO 3 and a catalytic amount of NaI in the mixed solvent afforded di...Alkylation of diethyl 3 oxoglutarate monoanion by 4 bromobutene to produce enone diester 3, subsequent alkylation of 3 with 4 bromo 1 butene using K 2CO 3 and a catalytic amount of NaI in the mixed solvent afforded dienone diester 4, which underwent decarboxylative hydrolysis when treated with 15% KOH in methanol under refluxing to provide dienone 5. The dienone afforded 2,8 dimethyl 1,7 dioxaspiroundecane 1 in good yield and high purity via an oxymercuration cyclisation reduction sequence.展开更多
End-stage liver diseases,such as cirrhosis and liver cancer caused by hepatitis B,are often combined with hepatic encephalopathy(HE);ammonia poisoning is posited as one of its main pathogenesis mechanisms.Ammonia is c...End-stage liver diseases,such as cirrhosis and liver cancer caused by hepatitis B,are often combined with hepatic encephalopathy(HE);ammonia poisoning is posited as one of its main pathogenesis mechanisms.Ammonia is closely related to autophagy,but the molecular mechanism of ammonia’s regulatory effect on autophagy in HE remains unclear.Sialylation is an essential form of glycosylation.In the nervous system,abnormal sialylation affects various physiological processes,such as neural development and synapse formation.ST3 β-galactoside α2,3-sialyltransferase 6(ST3GAL6)is one of the significant glycosyltransferases responsible for addingα2,3-linked sialic acid to substrates and generating glycan structures.We found that the expression of ST3GAL6 was upregulated in the brains of mice with HE and in astrocytes after ammonia induction,and the expression levels of α2,3-sialylated glycans and autophagy-related proteins microtubule-associated protein light chain 3(LC3)and Beclin-1 were upregulated in ammonia-induced astrocytes.These findings suggest that ST3GAL6 is related to autophagy in HE.Therefore,we aimed to determine the regulatory relationship between ST3GAL6 and autophagy.We found that silencing ST3GAL6 and blocking or degrading α2,3-sialylated glycans by way of Maackia amurensis lectin-II(MAL-II)and neuraminidase can inhibit autophagy.In addition,silencing the expression of ST3GAL6 can downregulate the expression of heat shock proteinβ8(HSPB8)and Bcl2-associated athanogene 3(BAG3).Notably,the overexpression of HSPB8 partially restored the reduced autophagy levels caused by silencing ST3GAL6 expression.Our results indicate that ST3GAL6 regulates autophagy through the HSPB8-BAG3 complex.展开更多
文摘Alkylation of diethyl 3 oxoglutarate monoanion by 4 bromobutene to produce enone diester 3, subsequent alkylation of 3 with 4 bromo 1 butene using K 2CO 3 and a catalytic amount of NaI in the mixed solvent afforded dienone diester 4, which underwent decarboxylative hydrolysis when treated with 15% KOH in methanol under refluxing to provide dienone 5. The dienone afforded 2,8 dimethyl 1,7 dioxaspiroundecane 1 in good yield and high purity via an oxymercuration cyclisation reduction sequence.
基金supported by the National Natural Science Foundation of China(No.82370592)the Discipline Construction Project of the Health System in Pudong New Area(No.PWZbr2022-15)the Pudong New Area Special Fund for Livelihood Research Project of Science and Technology Development Fund(No.PKJ2021-Y12),China.
文摘End-stage liver diseases,such as cirrhosis and liver cancer caused by hepatitis B,are often combined with hepatic encephalopathy(HE);ammonia poisoning is posited as one of its main pathogenesis mechanisms.Ammonia is closely related to autophagy,but the molecular mechanism of ammonia’s regulatory effect on autophagy in HE remains unclear.Sialylation is an essential form of glycosylation.In the nervous system,abnormal sialylation affects various physiological processes,such as neural development and synapse formation.ST3 β-galactoside α2,3-sialyltransferase 6(ST3GAL6)is one of the significant glycosyltransferases responsible for addingα2,3-linked sialic acid to substrates and generating glycan structures.We found that the expression of ST3GAL6 was upregulated in the brains of mice with HE and in astrocytes after ammonia induction,and the expression levels of α2,3-sialylated glycans and autophagy-related proteins microtubule-associated protein light chain 3(LC3)and Beclin-1 were upregulated in ammonia-induced astrocytes.These findings suggest that ST3GAL6 is related to autophagy in HE.Therefore,we aimed to determine the regulatory relationship between ST3GAL6 and autophagy.We found that silencing ST3GAL6 and blocking or degrading α2,3-sialylated glycans by way of Maackia amurensis lectin-II(MAL-II)and neuraminidase can inhibit autophagy.In addition,silencing the expression of ST3GAL6 can downregulate the expression of heat shock proteinβ8(HSPB8)and Bcl2-associated athanogene 3(BAG3).Notably,the overexpression of HSPB8 partially restored the reduced autophagy levels caused by silencing ST3GAL6 expression.Our results indicate that ST3GAL6 regulates autophagy through the HSPB8-BAG3 complex.
