Project description:We identify a previously uncharacterized human nucleoli-enriched protein FuHsi. FuHsi is an essential nucleolar molecule that regulates nucleolar biogenesis and mouse development.
Project description:Nucleolus is the organelle for ribosome biogenesis and sensing various types of stress. Its role in regulating stem cell fate is unclear. Here, we present multiple lines of evidence that nucleolar stress induced by interfering rRNA biogenesis can drive two-cell stage embryo-like (2C-like) transcriptional program and induce an expanded 2C-like cell population in mouse embryonic stem (mES) cells. Mechanistically, the liquid-liquid phase separation (LLPS) mediated by rRNA and nucleolar proteins maintains the formation of peri-nucleolar heterochromatin (PNH). When mES cells undergo rRNA biogenesis defect, the normal LLPS of nucleolus is disrupted, causing deconjugation of NCL/TRIM28 complex on PNH and changes of epigenetic state and 3D structure of PNH, which leads to Dux, a conserved multicopy retrogene defining the cleavage-specific transcriptional program in placental mammals, to be released from the PNH region, activation of 2C-like program and transition of mES cells to 2C-like cells. Embryos with rRNA biogenesis defect are incompatible to develop from 2-cell (2C) to blastocyte (BC) and appear to skew from the blastocyst to earlier cleavage embryo signatures. Our results highlight that nucleolar LLPS-mediated 3D chromatin structure reshaping of PNH compartment regulates the fate transition of mES cells to 2C-like cells. Our findings for the first time elucidate the novel roles of rRNA biogenesis in regulating the 2C-like and ES state homeostasis in cultured cells and suggest that rRNA biogenesis is a new molecular switch from nucleolus-unmatured 2C stage to nucleolus-matured BC stage during murine pre-implantation embryo development.
Project description:Nucleolus is the organelle for ribosome biogenesis and sensing various types of stress. Its role in regulating stem cell fate is unclear. Here, we present multiple lines of evidence that nucleolar stress induced by interfering rRNA biogenesis can drive two-cell stage embryo-like (2C-like) transcriptional program and induce an expanded 2C-like cell population in mouse embryonic stem (mES) cells. Mechanistically, the liquid-liquid phase separation (LLPS) mediated by rRNA and nucleolar proteins maintains the formation of peri-nucleolar heterochromatin (PNH). When mES cells undergo rRNA biogenesis defect, the normal LLPS of nucleolus is disrupted, causing deconjugation of NCL/TRIM28 complex on PNH and changes of epigenetic state and 3D structure of PNH, which leads to Dux, a conserved multicopy retrogene defining the cleavage-specific transcriptional program in placental mammals, to be released from the PNH region, activation of 2C-like program and transition of mES cells to 2C-like cells. Embryos with rRNA biogenesis defect are incompatible to develop from 2-cell (2C) to blastocyte (BC) and appear to skew from the blastocyst to earlier cleavage embryo signatures. Our results highlight that nucleolar LLPS-mediated 3D chromatin structure reshaping of PNH compartment regulates the fate transition of mES cells to 2C-like cells. Our findings for the first time elucidate the novel roles of rRNA biogenesis in regulating the 2C-like and ES state homeostasis in cultured cells and suggest that rRNA biogenesis is a new molecular switch from nucleolus-unmatured 2C stage to nucleolus-matured BC stage during murine pre-implantation embryo development.
Project description:Nucleolus is the organelle for ribosome biogenesis and sensing various types of stress. Its role in regulating stem cell fate is unclear. Here, we present multiple lines of evidence that nucleolar stress induced by interfering rRNA biogenesis can drive two-cell stage embryo-like (2C-like) transcriptional program and induce an expanded 2C-like cell population in mouse embryonic stem (mES) cells. Mechanistically, the liquid-liquid phase separation (LLPS) mediated by rRNA and nucleolar proteins maintains the formation of peri-nucleolar heterochromatin (PNH). When mES cells undergo rRNA biogenesis defect, the normal LLPS of nucleolus is disrupted, causing deconjugation of NCL/TRIM28 complex on PNH and changes of epigenetic state and 3D structure of PNH, which leads to Dux, a conserved multicopy retrogene defining the cleavage-specific transcriptional program in placental mammals, to be released from the PNH region, activation of 2C-like program and transition of mES cells to 2C-like cells. Embryos with rRNA biogenesis defect are incompatible to develop from 2-cell (2C) to blastocyte (BC) and appear to skew from the blastocyst to earlier cleavage embryo signatures. Our results highlight that nucleolar LLPS-mediated 3D chromatin structure reshaping of PNH compartment regulates the fate transition of mES cells to 2C-like cells. Our findings for the first time elucidate the novel roles of rRNA biogenesis in regulating the 2C-like and ES state homeostasis in cultured cells and suggest that rRNA biogenesis is a new molecular switch from nucleolus-unmatured 2C stage to nucleolus-matured BC stage during murine pre-implantation embryo development.
Project description:Nucleolus is the organelle for ribosome biogenesis and sensing various types of stress. Its role in regulating stem cell fate is unclear. Here, we present multiple lines of evidence that nucleolar stress induced by interfering rRNA biogenesis can drive two-cell stage embryo-like (2C-like) transcriptional program and induce an expanded 2C-like cell population in mouse embryonic stem (mES) cells. Mechanistically, the liquid-liquid phase separation (LLPS) mediated by rRNA and nucleolar proteins maintains the formation of peri-nucleolar heterochromatin (PNH). When mES cells undergo rRNA biogenesis defect, the normal LLPS of nucleolus is disrupted, causing deconjugation of NCL/TRIM28 complex on PNH and changes of epigenetic state and 3D structure of PNH, which leads to Dux, a conserved multicopy retrogene defining the cleavage-specific transcriptional program in placental mammals, to be released from the PNH region, activation of 2C-like program and transition of mES cells to 2C-like cells. Embryos with rRNA biogenesis defect are incompatible to develop from 2-cell (2C) to blastocyte (BC) and appear to skew from the blastocyst to earlier cleavage embryo signatures. Our results highlight that nucleolar LLPS-mediated 3D chromatin structure reshaping of PNH compartment regulates the fate transition of mES cells to 2C-like cells. Our findings for the first time elucidate the novel roles of rRNA biogenesis in regulating the 2C-like and ES state homeostasis in cultured cells and suggest that rRNA biogenesis is a new molecular switch from nucleolus-unmatured 2C stage to nucleolus-matured BC stage during murine pre-implantation embryo development.
Project description:Nucleolus is the organelle for ribosome biogenesis and sensing various types of stress. Its role in regulating stem cell fate is unclear. Here, we present multiple lines of evidence that nucleolar stress induced by interfering rRNA biogenesis can drive two-cell stage embryo-like (2C-like) transcriptional program and induce an expanded 2C-like cell population in mouse embryonic stem (mES) cells. Mechanistically, the liquid-liquid phase separation (LLPS) mediated by rRNA and nucleolar proteins maintains the formation of peri-nucleolar heterochromatin (PNH). When mES cells undergo rRNA biogenesis defect, the normal LLPS of nucleolus is disrupted, causing deconjugation of NCL/TRIM28 complex on PNH and changes of epigenetic state and 3D structure of PNH, which leads to Dux, a conserved multicopy retrogene defining the cleavage-specific transcriptional program in placental mammals, to be released from the PNH region, activation of 2C-like program and transition of mES cells to 2C-like cells. Embryos with rRNA biogenesis defect are incompatible to develop from 2-cell (2C) to blastocyte (BC) and appear to skew from the blastocyst to earlier cleavage embryo signatures. Our results highlight that nucleolar LLPS-mediated 3D chromatin structure reshaping of PNH compartment regulates the fate transition of mES cells to 2C-like cells. Our findings for the first time elucidate the novel roles of rRNA biogenesis in regulating the 2C-like and ES state homeostasis in cultured cells and suggest that rRNA biogenesis is a new molecular switch from nucleolus-unmatured 2C stage to nucleolus-matured BC stage during murine pre-implantation embryo development.
Project description:Nucleolar ribosomal DNA (rDNA) repeats control ribosome manufacturing. rDNA harbors a ribosomal RNA (rRNA) gene and an intergenic spacer (IGS). RNA polymerase (Pol) I transcribes rRNA genes yielding the rRNA components of ribosomes. Pol II at the IGS induces rRNA production by preventing Pol I from excessively synthesizing IGS non-coding RNAs (ncRNAs) that can disrupt nucleoli. At the IGS, Pol II regulatory processes and whether Pol I function can be beneficial remain unknown. Here, we identify IGS Pol II regulators, uncovering nucleolar optimization via IGS Pol I. Compartment-enriched proximity-dependent biotin identification (compBioID) showed enrichment of the TATA-less promoter-binding TBPL1 and transcription regulator PAF1 with IGS Pol II. TBPL1 localizes to TCT motifs, driving Pol II and Pol I and maintaining its baseline ncRNA levels. PAF1 promotes Pol II elongation, preventing unscheduled R-loops that hyper-restrain IGS Pol I and its ncRNAs. PAF1 or TBPL1 deficiency disrupts nucleolar organization and rRNA biogenesis. In PAF1-deficient cells, repressing unscheduled IGS R-loops rescues nucleolar organization and rRNA production. Depleting IGS Pol I-dependent ncRNAs is sufficient to compromise nucleoli. We present the interactome of nucleolar Pol II and show its control by TBPL1 and PAF1 ensures IGS Pol I ncRNAs maintaining nucleolar structure and operation.