金颖：Fox3 suppresses NFAT-mediaTED differentiation to maintain self-renewal of embryonic stem cells
金颖教授为分子发育生物学研究室主任，健康科学中心研究员。金教授介绍了Fox3通过抑制NFAT介导的分化维持了胚胎干细胞的自我更新的机制等前沿发现。Pluripotency-associaTED transcription factor Foxd3 is required for maintaining pluripotent cells. However, molecular mechanisms underlying its function are largely unknown. Here, we report that Foxd3 suppresses differentiation induced by Calcineurin-NFAT signaling to maintain the ESC identity. Mechanistically, Foxd3 interacts with NFAT proteins and recruits co-repressor Tle4, a member of the Tle suppressor family highly expressed in undifferentiaTED ESCs, to repress NFATc3’s transcriptional activities. Furthermore, global transcriptome analysis shows that Foxd3 and NFATc3 co-regulate a set of differentiation-associaTED genes in ESCs. Collectively, our study establishes a molecular and functional link between a pluripotency-associaTED factor and an important ESC differentiation-inducing pathway.
秦正红：DRAM1 regulates autophagy flux and Bid-mediaTED cell death via lysosomes
秦正红，博士，教授，神经药理专业博士生导师。1994年在美国宾州医学院研究生院获博士学位，先后在美国国家卫生研究院(NIH)及麻省总医院和哈佛大学医学院从事研究工作。2003年从哈佛大学引进，现为苏州大学医学部基础医学与生物科学学院科研中心实验室主任，中国药理学会生化药理学专业委员会委员，中国药理学会神经药理学专业委员会委员，美国神经科学学会会员。Damage-regulaTED autophagy modulator1 (DRAM1), a novel TP53 target gene, is an evolutionarily conserved lysosomal protein and plays an essential role in TP53-dependent autophagy activation and apoptosis (Crighton et al, 2006). However, the mechanisms by which DRAM1 promotes autophagy and apoptosis are not clear. 3-Nitropropionic acid (3-NP) is an inhibitor of mitochondrial respiratory complex II. Intrastriatal administration of 3-NP produces neuropathology resemble to Huntington disease. 3-NP-induced neuronal death was involved in autophagy and apoptosis. In vitro studies with 3-NP in TP53 wt and null cells, 3-NP or CCCP increased the protein levels of DRAM1 in a TP53-dependent or independent manner. DRAM1 induction contribuTED to 3-NP-induced autophagy activation. Knock-down of DRAM1 with siRNA inhibiTED the activity of V-ATPase, acidification of lysosomes and activation of lysosomal proteases. Knock-down of DRAM1 reduced the clearance of autophagososmes. 3-NP also induced a transcription independent upregulation of BAX protein levels. Knock-down of DRAM1 suppressed the increase in BAX levels. Co-immunoprecipitation and pull-down studies revealed an interaction of DRAM1 and BAX protein. Stably expression of exogenous DRAM1 increased the half-life of BAX. Upregulation of DRAM1 recruiTED BAX to lysosomes and induced cathepsin B-dependent cleavage of Bid and cytochrome c release. Knockdown of DRAM1, BAX or inhibition of lysosomal enzymes reduced 3-NP-induced cytochrome c release and cell death. These data suggest that DRAM1 plays important roles in regulating autophagy flux and apoptosis. DRAM1 promotes autophagy flux through a mechanism involves activation of V-ATPase and enhances the acidification of lysosomes. DRAM1 promotes apoptosis via a mechanism involving recruitment of BAX to lysosomes to trigger cathepsin B-mediaTED Bid cleavage.
Chaperone-assisTED protein folding
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