In this study, we investigated the role of the TYRO3/Akt signaling pathway in hypoxic injury to hippocampal neurons. 3-（4,5-Dimethylthiazol-2-yl）-2,5-diphenyltetrazolium bromide assay showed that hypoxia inhibited t...In this study, we investigated the role of the TYRO3/Akt signaling pathway in hypoxic injury to hippocampal neurons. 3-（4,5-Dimethylthiazol-2-yl）-2,5-diphenyltetrazolium bromide assay showed that hypoxia inhibited the proliferation and viability of hippocampal neurons. Terminal deoxynucleotidyl transferase-mediated d UTP nick end labeling assay demonstrated that hypoxia induced neuronal apoptosis in a time-dependent manner, with a greater number of apoptotic cells with longer hypoxic exposure. Immunofluorescence labeling revealed that hypoxia suppressed TYRO3 expression. Western blot assay showed that hypoxia decreased Akt phosphorylation levels in a time-dependent manner. Taken together, these findings suggest that hypoxia inhibits the proliferation of hippocampal neurons and promotes apoptosis, and that the inhibition of the TYRO3/Akt signaling pathway plays an important role in hypoxia-induced neuronal injury.展开更多
The Tyro3, Axl and Mer (TAM) receptor tyrosine kinases are activated by endogenous ligands, protein S1 (PROS1) and growth arrest-specific gene 6 (Gas6), and those have important effects on cell biology. These receptor...The Tyro3, Axl and Mer (TAM) receptor tyrosine kinases are activated by endogenous ligands, protein S1 (PROS1) and growth arrest-specific gene 6 (Gas6), and those have important effects on cell biology. These receptors (Rs) can be shad from the cell membrane and their soluble(s) forms can be found in plasma. We investigated the fluctuation and interactive role of sTAMRs and its ligands in patients with hepatocellular carcinoma (HCC), hepatitis groups, and healthy normal adult controls (NC). The measurement cases were 45 patients with HCC group (stage 1 in 4, stage 2 in 8, stage 3 in 16, and stage 4 in 17), 4 patients with fulminant hepatitis (FH), 14 patients with acute hepatitis (AH), 10 patients with chronic hepatitis (CH), 16 patients with liver cirrhosis (LC), and 20 NCs matched by age. Plasma levels of three sTAMRs and their ligands were measured by ELISA. In comparison with NCs, Gas6, des-γ-carboxy Gas6, and sTAMRs levels were significantly higher in HCC patients, but free PROS1 levels were significantly lower. The sTyro3 and sAxl levels peaked HCC stages 2 and 3 respectively, and gradually decreased afterwards while maintaining high levels. sMer levels increased with the progression of HCC. Gas6 and des-γ-carboxy Gas6 levels gradually increased, and PROS1 levels decreased with the progression of HCC. Gas6 levels were positively correlated with sAxl levels, whereas sMer levels were negatively correlated with free PROS1 levels. sTAMRs and Gas6 levels increased in parallel to the progression of HCC fibrosis. Through the progression of HCC, Axl played the major role in TAMRs activation. However, sTYro3 continued increasing rapidly from the early stage, and that of Mer increased throughout the progression. Roles of Axl may be changed in Mer, because des-γ-carboxy Gas6 levels increasing with Gas6 in the advanced stage of HCC cannot send a signal to Axl.展开更多
Objective Tyro-3 and Axl receptors are expressed in brain in a region-specific manner and their bioactivities in the central nervous system remain still elusive.The aim of the present study was to investigate their fu...Objective Tyro-3 and Axl receptors are expressed in brain in a region-specific manner and their bioactivities in the central nervous system remain still elusive.The aim of the present study was to investigate their functions in neuronal differentiation.Methods PC12 cells overexpressing Tyro-3 or Axl were established by transfection with full-length CMV-Tyro3-eCFP or CMV-Axl-eGFP plasmid,respectively.CMV-eGFP plasmid served as a control vector.After that,the fluorescence intensity and distributions of green fluorescent protein （GFP） and cyan fluorescent protein （CFP） in the cells with or without nerve growth factor （NGF） treatment were real-time monitored.Results Expressions of Tyro-3 and Axl receptors were under the regulation of NGF and associated with neuronal differentiation.This was not observed in CMV-eGFP-transfected PC12 cells.Besides,confocal microscopy revealed that NGF affected intracellular localization of full-length Axl-eGFP and Tyro-3eCFP in PC12 cells.Moreover,the development of outgrowth of differentiated PC12 cells under stimulation of NGF was promoted by overexpression of Tyro-3 or Axl.Conclusion Expressions of Tyro-3 and Axl receptors are under the regulation of NGF and are involved in NGF-induced neuronal differentiation of PC12 cells.展开更多
Tyro3,Axl,and Mertk(TAM)receptors play multiple roles in a myriad of physiological and pathological processes,varying from promoting the phagocytic clearance of apoptotic cells,sustaining the immune and inflammatory h...Tyro3,Axl,and Mertk(TAM)receptors play multiple roles in a myriad of physiological and pathological processes,varying from promoting the phagocytic clearance of apoptotic cells,sustaining the immune and inflammatory homeostasis,maintaining the blood-brain barrier(BBB)integrity and central nervous system(CNS)homeostasis,to mediating cancer malignancy and chemoresistance.Growth arrest-specific protein 6(Gas6)and protein S(Pros1)are the two ligands that activate TAM receptors.Recently,TAM receptors have been reported to mediate cell entry and infection of multitudinous enveloped viruses in a manner called apoptotic mimicry.Moreover,TAM receptors are revitalized during viral entry and infection,which sequesters innate immune and inflammatory responses,facilitating viral replication and immune evasion.However,accumulating evidence have now proposed that TAM receptors are not required for the infection of these viruses in vivo.In addition,TAM receptors protect mice against the CNS infection of neuroinvasive viruses and relieve the brain lesions during encephalitis.These protective effects are achieved through maintaining BBB integrity,attenuating proinflammatory cytokine production,and promoting neural cell survival.TAM receptors also regulate the programmed cell death modes of virus-infected cells,which have profound impacts on the pathogenesis and outcome of infection.Here,we systematically review the functionalities and underlying mechanisms of TAM receptors and propose the potential application of TAM agonists to prevent severe viral encephalitis.展开更多
The TAM family of receptors is preferentially expressed by professional and non-professional phagocytes,including macrophages,dendritic cells and natural killer cells in the immune system,osteoclasts in bone,Sertoli c...The TAM family of receptors is preferentially expressed by professional and non-professional phagocytes,including macrophages,dendritic cells and natural killer cells in the immune system,osteoclasts in bone,Sertoli cells in testis,and retinal pigmental epithelium cells in the retina.Mutations in the Mertk single gene or in different combinations of the double or triple gene mutations in the same cell cause complete or partial impairment in phagocytosis of their preys;and as a result,either the normal apoptotic cells cannot be efficiently removed or the tissue neighbor cells die by apoptosis.This scenario of TAM regulation represents a widely adapted model system used by phagocytes in all different tissues.The present review will summarize current known functional roles of TAM receptors and their ligands,Gas 6 and protein S,in the regulation of phagocytosis.展开更多
基金supported by the National Natural Science Foundation of China,No.81001541the Natural Science Foundation of Fujian Province of China,No.2013J01331
文摘In this study, we investigated the role of the TYRO3/Akt signaling pathway in hypoxic injury to hippocampal neurons. 3-（4,5-Dimethylthiazol-2-yl）-2,5-diphenyltetrazolium bromide assay showed that hypoxia inhibited the proliferation and viability of hippocampal neurons. Terminal deoxynucleotidyl transferase-mediated d UTP nick end labeling assay demonstrated that hypoxia induced neuronal apoptosis in a time-dependent manner, with a greater number of apoptotic cells with longer hypoxic exposure. Immunofluorescence labeling revealed that hypoxia suppressed TYRO3 expression. Western blot assay showed that hypoxia decreased Akt phosphorylation levels in a time-dependent manner. Taken together, these findings suggest that hypoxia inhibits the proliferation of hippocampal neurons and promotes apoptosis, and that the inhibition of the TYRO3/Akt signaling pathway plays an important role in hypoxia-induced neuronal injury.
文摘The Tyro3, Axl and Mer (TAM) receptor tyrosine kinases are activated by endogenous ligands, protein S1 (PROS1) and growth arrest-specific gene 6 (Gas6), and those have important effects on cell biology. These receptors (Rs) can be shad from the cell membrane and their soluble(s) forms can be found in plasma. We investigated the fluctuation and interactive role of sTAMRs and its ligands in patients with hepatocellular carcinoma (HCC), hepatitis groups, and healthy normal adult controls (NC). The measurement cases were 45 patients with HCC group (stage 1 in 4, stage 2 in 8, stage 3 in 16, and stage 4 in 17), 4 patients with fulminant hepatitis (FH), 14 patients with acute hepatitis (AH), 10 patients with chronic hepatitis (CH), 16 patients with liver cirrhosis (LC), and 20 NCs matched by age. Plasma levels of three sTAMRs and their ligands were measured by ELISA. In comparison with NCs, Gas6, des-γ-carboxy Gas6, and sTAMRs levels were significantly higher in HCC patients, but free PROS1 levels were significantly lower. The sTyro3 and sAxl levels peaked HCC stages 2 and 3 respectively, and gradually decreased afterwards while maintaining high levels. sMer levels increased with the progression of HCC. Gas6 and des-γ-carboxy Gas6 levels gradually increased, and PROS1 levels decreased with the progression of HCC. Gas6 levels were positively correlated with sAxl levels, whereas sMer levels were negatively correlated with free PROS1 levels. sTAMRs and Gas6 levels increased in parallel to the progression of HCC fibrosis. Through the progression of HCC, Axl played the major role in TAMRs activation. However, sTYro3 continued increasing rapidly from the early stage, and that of Mer increased throughout the progression. Roles of Axl may be changed in Mer, because des-γ-carboxy Gas6 levels increasing with Gas6 in the advanced stage of HCC cannot send a signal to Axl.
基金supported by the National Basic Research Development Program of China(No.2006CB500700)the National Natural Science Foundation of China(No. 30900421/c090201)
文摘Objective Tyro-3 and Axl receptors are expressed in brain in a region-specific manner and their bioactivities in the central nervous system remain still elusive.The aim of the present study was to investigate their functions in neuronal differentiation.Methods PC12 cells overexpressing Tyro-3 or Axl were established by transfection with full-length CMV-Tyro3-eCFP or CMV-Axl-eGFP plasmid,respectively.CMV-eGFP plasmid served as a control vector.After that,the fluorescence intensity and distributions of green fluorescent protein （GFP） and cyan fluorescent protein （CFP） in the cells with or without nerve growth factor （NGF） treatment were real-time monitored.Results Expressions of Tyro-3 and Axl receptors were under the regulation of NGF and associated with neuronal differentiation.This was not observed in CMV-eGFP-transfected PC12 cells.Besides,confocal microscopy revealed that NGF affected intracellular localization of full-length Axl-eGFP and Tyro-3eCFP in PC12 cells.Moreover,the development of outgrowth of differentiated PC12 cells under stimulation of NGF was promoted by overexpression of Tyro-3 or Axl.Conclusion Expressions of Tyro-3 and Axl receptors are under the regulation of NGF and are involved in NGF-induced neuronal differentiation of PC12 cells.
基金supported by the National Natural Science Foundation of China(81671971,81871641,81972979,U1902210 and U1602223)the Scientific Research Plan of the Beijing Municipal Education Committee(KM201710025002)+1 种基金the Key Project of Beijing Natural Science Foundation B(KZ201810025035)the Support Project of High-level Teachers in Beijing Municipal Universities in the Period of 13th Five-year Plan(IDHT20190510)
文摘Tyro3,Axl,and Mertk(TAM)receptors play multiple roles in a myriad of physiological and pathological processes,varying from promoting the phagocytic clearance of apoptotic cells,sustaining the immune and inflammatory homeostasis,maintaining the blood-brain barrier(BBB)integrity and central nervous system(CNS)homeostasis,to mediating cancer malignancy and chemoresistance.Growth arrest-specific protein 6(Gas6)and protein S(Pros1)are the two ligands that activate TAM receptors.Recently,TAM receptors have been reported to mediate cell entry and infection of multitudinous enveloped viruses in a manner called apoptotic mimicry.Moreover,TAM receptors are revitalized during viral entry and infection,which sequesters innate immune and inflammatory responses,facilitating viral replication and immune evasion.However,accumulating evidence have now proposed that TAM receptors are not required for the infection of these viruses in vivo.In addition,TAM receptors protect mice against the CNS infection of neuroinvasive viruses and relieve the brain lesions during encephalitis.These protective effects are achieved through maintaining BBB integrity,attenuating proinflammatory cytokine production,and promoting neural cell survival.TAM receptors also regulate the programmed cell death modes of virus-infected cells,which have profound impacts on the pathogenesis and outcome of infection.Here,we systematically review the functionalities and underlying mechanisms of TAM receptors and propose the potential application of TAM agonists to prevent severe viral encephalitis.
基金This study was partially supported by NIH EY018830,RR017702,and RR018733Research to Prevent Blindnessand the National Natural Science Foundation of China(Grant Nos.30400229,30670643 and 30870788).
文摘The TAM family of receptors is preferentially expressed by professional and non-professional phagocytes,including macrophages,dendritic cells and natural killer cells in the immune system,osteoclasts in bone,Sertoli cells in testis,and retinal pigmental epithelium cells in the retina.Mutations in the Mertk single gene or in different combinations of the double or triple gene mutations in the same cell cause complete or partial impairment in phagocytosis of their preys;and as a result,either the normal apoptotic cells cannot be efficiently removed or the tissue neighbor cells die by apoptosis.This scenario of TAM regulation represents a widely adapted model system used by phagocytes in all different tissues.The present review will summarize current known functional roles of TAM receptors and their ligands,Gas 6 and protein S,in the regulation of phagocytosis.
