The limited regenerative capacity of neuronal cells requires tight orchestration of cell death and survival regulation in the context of longevity, age-associated diseases as well as during the development of the nerv...The limited regenerative capacity of neuronal cells requires tight orchestration of cell death and survival regulation in the context of longevity, age-associated diseases as well as during the development of the nervous system. Subordinate to genetic networks epigenetic mechanisms like DNA methylation and histone modifications are involved in the regulation of neuronal development, function and aging. DNA methylation by DNA methyltransferases （DNMTs）, mostly correlated with gene silencing, is a dynamic and reversible process. In addition to their canonical actions performing cytosine methylation, DNMTs influence gene expression by interactions with histone modifying enzymes or complexes increasing the complexity of epigenetic transcriptional networks. DNMTs are expressed in neuronal progenitors, post-mi- totic as well as adult neurons. In this review, we discuss the role and mode of actions of DNMTs including downstream networks in the regulation of neuronal survival in the developing and aging nervous system and its relevance for associated disorders.展开更多
Recent studies regarding neuronal differentiation of mesenchymal stem cells （MSCs） have primarily focused on induction methods and transplantation in vivo. However, knowledge about the intrinsic regulatory mechanism...Recent studies regarding neuronal differentiation of mesenchymal stem cells （MSCs） have primarily focused on induction methods and transplantation in vivo. However, knowledge about the intrinsic regulatory mechanisms underlying neuronal induction of MSCs remains limited and unclear. OBJECTIVE： To elucidate the role of JAK-STAT3 signaling pathway during neuronal differentiation of MSCs using a combination of the JAK-STAT3 signaling inhibitor AG490 and growth factors. DESIGN, TIME AND SETTING： Neural, molecular, biomedical, in vitro experiment was performed at the Laboratory of Pharmacology, School of Pharmacy, Nanjing Medical University between March and December 2008 MATERIALS： An inhibitor of the JAK-STAT3 signaling pathway was purchased from Calbiochem, USA. Antibody kit for total and phosphorylated STAT3 was purchased from Cell Signaling, USA. METHODS： MSCs from passage 3 were assigned to non-induced, growth factor, and AG490 groups. MAIN OUTCOME MEASURE： The number of cells expressing neuron-specific enolase, microtubule-associated protein, and glial fibrillary acidic protein were determined by immunocytochemistry. Total and phosphorylated （Tyr705） expression levels of STAT3 protein were measured by Western blot analysis. RESULTS： MSCs were transdifferentiated into neuronal- and astrocyte-like phenotypes through the induction of epidermal growth factor, basic fibroblast growth factor, and brain-derived neurotrophic factor. In addition, the JAK-STAT3 signaling pathway was significantly activated during neural differentiation. Expression of phosphorylated （Tyr705） STAT3 was inhibited with AG490 （5 pmol/L） prior to neural induction with epidermal growth factor, basic fibroblast growth factor, and brain-derived neurotrophic factor; proportion of astrocyte-like cells was significantly reduced （P 〈 0.01）, and the proportion of neuronal-like phenotypes was significantly increased （P〈 0.01）. CONCLUSION： JAK-STAT3 signaling pathway was shown to regulate neuronal induction of bone marrow MSCs. The proportion of MSC-induced neuronal-like cells was increased following treatment with the JAK-STAT3 signaling inhibitor AG490.展开更多
Aging has been considered a natural process of any living being.The rate of aging depends on many factors,including genetic and environmental factors.For this reason,many researchers in this field suggest that aging i...Aging has been considered a natural process of any living being.The rate of aging depends on many factors,including genetic and environmental factors.For this reason,many researchers in this field suggest that aging is an epigenetic process.Nowadays,the age groups have undergone a change.展开更多
文摘The limited regenerative capacity of neuronal cells requires tight orchestration of cell death and survival regulation in the context of longevity, age-associated diseases as well as during the development of the nervous system. Subordinate to genetic networks epigenetic mechanisms like DNA methylation and histone modifications are involved in the regulation of neuronal development, function and aging. DNA methylation by DNA methyltransferases （DNMTs）, mostly correlated with gene silencing, is a dynamic and reversible process. In addition to their canonical actions performing cytosine methylation, DNMTs influence gene expression by interactions with histone modifying enzymes or complexes increasing the complexity of epigenetic transcriptional networks. DNMTs are expressed in neuronal progenitors, post-mi- totic as well as adult neurons. In this review, we discuss the role and mode of actions of DNMTs including downstream networks in the regulation of neuronal survival in the developing and aging nervous system and its relevance for associated disorders.
基金the National Nature Science Foundation of China, No. 30973092"Xingwei" Project Medical Emphasis Grant from Jiangsu Province, No. RC2007062
文摘Recent studies regarding neuronal differentiation of mesenchymal stem cells （MSCs） have primarily focused on induction methods and transplantation in vivo. However, knowledge about the intrinsic regulatory mechanisms underlying neuronal induction of MSCs remains limited and unclear. OBJECTIVE： To elucidate the role of JAK-STAT3 signaling pathway during neuronal differentiation of MSCs using a combination of the JAK-STAT3 signaling inhibitor AG490 and growth factors. DESIGN, TIME AND SETTING： Neural, molecular, biomedical, in vitro experiment was performed at the Laboratory of Pharmacology, School of Pharmacy, Nanjing Medical University between March and December 2008 MATERIALS： An inhibitor of the JAK-STAT3 signaling pathway was purchased from Calbiochem, USA. Antibody kit for total and phosphorylated STAT3 was purchased from Cell Signaling, USA. METHODS： MSCs from passage 3 were assigned to non-induced, growth factor, and AG490 groups. MAIN OUTCOME MEASURE： The number of cells expressing neuron-specific enolase, microtubule-associated protein, and glial fibrillary acidic protein were determined by immunocytochemistry. Total and phosphorylated （Tyr705） expression levels of STAT3 protein were measured by Western blot analysis. RESULTS： MSCs were transdifferentiated into neuronal- and astrocyte-like phenotypes through the induction of epidermal growth factor, basic fibroblast growth factor, and brain-derived neurotrophic factor. In addition, the JAK-STAT3 signaling pathway was significantly activated during neural differentiation. Expression of phosphorylated （Tyr705） STAT3 was inhibited with AG490 （5 pmol/L） prior to neural induction with epidermal growth factor, basic fibroblast growth factor, and brain-derived neurotrophic factor; proportion of astrocyte-like cells was significantly reduced （P 〈 0.01）, and the proportion of neuronal-like phenotypes was significantly increased （P〈 0.01）. CONCLUSION： JAK-STAT3 signaling pathway was shown to regulate neuronal induction of bone marrow MSCs. The proportion of MSC-induced neuronal-like cells was increased following treatment with the JAK-STAT3 signaling inhibitor AG490.
文摘Aging has been considered a natural process of any living being.The rate of aging depends on many factors,including genetic and environmental factors.For this reason,many researchers in this field suggest that aging is an epigenetic process.Nowadays,the age groups have undergone a change.
