Matrix metalloproteinases (MMPs) are a family of extracellular proteases capable of degrading various proteinaceous components of the extracellular matrix (ECM).They have been implicated to play important roles in a n...Matrix metalloproteinases (MMPs) are a family of extracellular proteases capable of degrading various proteinaceous components of the extracellular matrix (ECM).They have been implicated to play important roles in a number of developmental and pathological processes, such as tumor metastasis and inflammation. Relatively few studies have been carried out to investigate the function of MMPs during postembryonic organ-development. Using Xenopus laevis development as a model system, we demonstrate here that three MMPs, stromelysin-3 (ST3),collagenases-3 (Col3), and Col4, have distinct spatial and temporal expression profiles during metamorphosis as the tadpole transforms into a frog. In situ hybridizations reveal a tight, but distinct, association of individual MMPs with tissue remodeling in the tail and intestine during metamorphosis. In particular, ST3 expression is strongly correlated with apoptosis in both organs as demonstrated by analyses of serial sections with in situ hybridization for ST3 mRNA and TUNEL (terminal deoxyribonucleotidyl transferase-mediated dUTP-biotin nick end labeling) for apoptosis, respectively. On the other hand, Col3 and Col4 MMPs in Xenopus laevis development are present in regions where extensive connective tissue remodeling take place. These results indicate that ST3 is likely to play a role in ECM-remodeling that facilitateapoptotic tissue remodeling or resorption while Col3 and Col4 appear to participate in connective tissue degradation during development.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Matrix metalloproteinases (MMPs) are a family of extracellular proteases capable of degrading various proteinaceous components of the extracellular matrix (ECM).They have been implicated to play important roles in a number of developmental and pathological processes, such as tumor metastasis and inflammation. Relatively few studies have been carried out to investigate the function of MMPs during postembryonic organ-development. Using Xenopus laevis development as a model system, we demonstrate here that three MMPs, stromelysin-3 (ST3),collagenases-3 (Col3), and Col4, have distinct spatial and temporal expression profiles during metamorphosis as the tadpole transforms into a frog. In situ hybridizations reveal a tight, but distinct, association of individual MMPs with tissue remodeling in the tail and intestine during metamorphosis. In particular, ST3 expression is strongly correlated with apoptosis in both organs as demonstrated by analyses of serial sections with in situ hybridization for ST3 mRNA and TUNEL (terminal deoxyribonucleotidyl transferase-mediated dUTP-biotin nick end labeling) for apoptosis, respectively. On the other hand, Col3 and Col4 MMPs in Xenopus laevis development are present in regions where extensive connective tissue remodeling take place. These results indicate that ST3 is likely to play a role in ECM-remodeling that facilitateapoptotic tissue remodeling or resorption while Col3 and Col4 appear to participate in connective tissue degradation during development.
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.
