Project description:As an evolutionarily conserved master regulator of metabolism, mechanistic target of rapamycin complex 1 (mTORC1) regulates cell states and fates in development, cancer and aging. mTORC1 activity regulation was critical for pluripotent stem cells maintenance and cell fate transitions. Inhibition of mTORC1 induces embryonic stem cells (ESCs) entry into a paused state which reversibly arrests self-renewal leaving pluripotency intact. Hyperactivation of mTORC1 impedes both pluripotency re-establishment and exit of PSCs. As shown that mTORC1 mediates TFE3 nuclear translocation block pluripotency exit, whether similar mechanisms through transcription factor TFE3 are involved in these processes, and the detailed mechanism by which mTORC1-TFE3 regulates critical transcriptional processes for these transitions, remain unclear. In this study, we demonstrate that the nuclear translocation of TFE3, induced by hyperactivation of mTORC1, results in its binding to the nucleosome remodeling and deacetylation (NuRD) complex in both re-establishment and exit of pluripotency. This interaction inhibits the expression of various crucial genes during different fate transitions of PSCs. Our findings uncover a common and key role of TFE3-NuRD association as mediator of mTORC1 to block pluripotent cell fate transitions, with implications for various fields including physiological and pathological diseases.
Project description:As an evolutionarily conserved master regulator of metabolism, mechanistic target of rapamycin complex 1 (mTORC1) regulates cell states and fates in development, cancer and aging. mTORC1 activity regulation was critical for pluripotent stem cells maintenance and cell fate transitions. Inhibition of mTORC1 induces embryonic stem cells (ESCs) entry into a paused state which reversibly arrests self-renewal leaving pluripotency intact. Hyperactivation of mTORC1 impedes both pluripotency re-establishment and exit of PSCs. As shown that mTORC1 mediates TFE3 nuclear translocation block pluripotency exit, whether similar mechanisms through transcription factor TFE3 are involved in these processes, and the detailed mechanism by which mTORC1-TFE3 regulates critical transcriptional processes for these transitions, remain unclear. In this study, we demonstrate that the nuclear translocation of TFE3, induced by hyperactivation of mTORC1, results in its binding to the nucleosome remodeling and deacetylation (NuRD) complex in both re-establishment and exit of pluripotency. This interaction inhibits the expression of various crucial genes during different fate transitions of PSCs. Our findings uncover a common and key role of TFE3-NuRD association as mediator of mTORC1 to block pluripotent cell fate transitions, with implications for various fields including physiological and pathological diseases.
Project description:Differentiation of mammalian pluripotent cells involves large-scale changes in transcription and, among the molecules that orchestrate these changes, chromatin remodellers are essential to initiate, establish and maintain a new gene regulatory network. The NuRD complex is a highly conserved chromatin remodeller which fine-tunes gene expression in embryonic stem cells. While the function of NuRD in mouse pluripotent cells has been well defined, no study yet has defined NuRD function in human pluripotent cells. We investigated the structure and function of NuRD in human induced pluripotent stem cells (hiPSCs). Using immunoprecipitation followed by mass-spectrometry in hiPSCs and in naive or primed mouse pluripotent stem cells, we find that NuRD structure and biochemical interactors are generally conserved. Using RNA sequencing, we find that, whereas in mouse primed stem cells and in mouse naive ES cells, NuRD is required for an appropriate level of transcriptional response to differentiation signals, hiPSCs require NuRD to initiate these responses. This difference indicates that mouse and human cells interpret and respond to induction of differentiation differently.
Project description:The exit from pluripotency or pluripotent-somatic transition (PST) landmarks an event of mammalian development, and is also a representative cell-fate transition model, but remains largely unresolved. Recently, we reported construction of robust JUN-induced PST completed in one cell cycle and whose dominant regulator SS18/BAFs (Brg1/Brahma-associated factors). However, the transition process in the chromatin architecture and the roles played by BAF are still unknown. Here we report the dynamic changes of chromatin accessibility during JUN-induced PST. Meanwhile, SS18/BAFs mediates PST process by relocating from pluripotent loci to AP-1 associated ones and once compromised, JUN fails to open chromatin and PST will be delayed. Furthermore, we show that the relocation of SS18/BAF partially relays on histone modification H3K27ac, instead of JUN-centric protein-protein interaction. These results reveal the orchestration of master transcription factor, epigenetic machine, and histone modification in the cell fate transition.
Project description:Lysosomal degradation of the endoplasmic reticulum (ER) via autophagy (ER-phagy) is emerging as a critical regulator of cell homeostasis and function1. The recent identification of ER-phagy receptors has shed light on the molecular mechanism underlining this process; however, the signaling pathways regulating ER-phagy in response to cellular needs are still largely unknown. We found that the nutrient responsive transcription factors TFEB and TFE3 - master regulators of lysosomal biogenesis and autophagy2- control ER-phagy by inducing the expression of the ER-phagy receptor FAM134B. The TFEB/TFE3-FAM134B axis promotes ER-phagy activation upon prolonged starvation. In addition, we discovered that this pathway is activated in chondrocytes by FGF signaling, a critical regulator of cell differentiation 3. FGF signaling induces a JNK-dependent proteasomal degradation of the insulin receptor substrate 1, which inhibits the insulin-PI3K-PKB/Akt-mTORC1 pathway and promotes TFEB/TFE3 nuclear translocation and FAM134B induction. Consistent with a role of the TFEB/TFE3-FAM134B axis in chondrocytes, FAM134B knock-down impairs cartilage growth and mineralization in medaka fish. This study identifies a new signaling pathway that allows ER-phagy to respond to both metabolic and developmental cues.
Project description:Tbx3, a member of the T-box family, plays important roles in development, stem cells, nuclear reprogramming and cancer. Loss of Tbx3 induces differentiation in mouse embryonic stem cells (mESCs). However, we show that mESCs exist in an alternate stable pluripotent state in the absence of Tbx3. In-depth transcriptome analysis of this mESC state reveals Dppa3 as a direct downstream target of Tbx3. Also Tbx3 facilitates the cell fate transition from pluripotent cells to mesoderm progenitors by directly repressing Wnt pathway members required for differentiation. Wnt signaling regulates differentiation of mESCs into mesoderm progenitors and helps maintain a naïve pluripotent state. We show that Tbx3, a downstream target of Wnt signaling, fine-tunes these divergent roles of Wnt signaling in mESCs. In conclusion, we identify a signaling-TF axis that controls the exit of mESCs from a self-renewing pluripotent state towards mesoderm differentiation. ChIPSeq and RNASeq (population and single cell) was performed on the indicated cell lines. Replicates are indicated as needed. The mm9 genome assembly was used. For single cell mRNA-Seq preparation, SSEA1+DAPI- mESCs were sorted and collected.
Project description:Translocation renal cell carcinoma (tRCC) most commonly involves an ASPSCR1-TFE3 fusion, but molecular mechanisms remain elusive and animal models are lacking. Here, we show that human ASPSCR1-TFE3 driven by Pax8-Cre (a credentialed clear cell RCC driver) disrupted nephrogenesis and glomerular development, causing neonatal death, while the clear cell RCC failed driver, Sglt2-Cre, induced aggressive tRCC (as well as alveolar soft part sarcoma) with complete penetrance and short latency. However, in both contexts, ASPSCR1-TFE3 led to characteristic morphological cellular changes, loss of epithelial markers, and an epithelial-mesenchymal transition. Electron microscopy of tRCC tumors showed lysosome expansion, and functional studies revealed simultaneous activation of autophagy and mTORC1 pathways. Comparative genomic analyses encompassing an institutional human tRCC cohort (including a hitherto unreported SFPQ-TFEB fusion) and a variety of tumorgraft models (ASPSCR1-TFE3, PRCC-TFE3, SFPQ-TFE3, RBM10-TFE3, and MALAT1-TFEB) disclosed significant convergence in canonical pathways (cell cycle, lysosome, and mTORC1) and less established pathways such as Myc, E2F, and inflammation (IL-6/JAK/STAT3, interferon-γ, TLR signaling, systemic lupus, etc.). Therapeutic trials (adjusted for human drug exposures) showed antitumor activity of cabozantinib. Overall, this study provides insight into MiT/TFE-driven tumorigenesis, including the cell of origin, and characterizes diverse mouse models available for research
Project description:Cell fate decision involves rewiring of the genome, but remains poorly understood at the chromatin level. We report a system to reprogramming somatic cells to pluripotency by four factor combination (Sall4, Esrrb, Jdp2, Glis1). Mechanism study demonstrate that the Sall4-NuRD axis plays a critical role in the early phase of reprogramming. These results identify a previously unrecognized role of NuRD in reprogramming, may help establish early chromatin closing as a pre-requisite step in cell fate control.