Project description:Development requires the cooperation of tissue-specifically and ubiquitously expressed transcription factors, such as Sp-family members. However, the molecular details of how ubiquitous factors participate in developmental processes are still unclear. We previously showed that during the differentiation of embryonic stem cells lacking Sp1 DNA binding activity (Sp1DDBD/DDBD cells), early blood progenitors are formed. However, gene expression during differentiation becomes progressively deregulated and terminal differentiation is blocked. Here we studied the cooperation of Sp1 and its homologue Sp3 in hematopoietic development and demonstrate that Sp1 and Sp3 binding sites largely overlap. Sp3 cooperates with Sp1DDBD/DDBD cells but is unable to support hematopoiesis in the complete absence of Sp1. Using single cell gene expression analysis, we show that the lack of Sp1 DNA binding leads to a distortion of cell fate decision timing, indicating that stable chromatin binding of Sp1 is required to maintain robust differentiation trajectories.
Project description:Development requires the cooperation of tissue-specific and ubiquitously expressed transcription factors, such as Sp-family members. However, the molecular details of how ubiquitous factors participate in developmental processes are still unclear. We previously showed that during the differentiation of embryonic stem cells lacking Sp1 DNA binding activity (Sp1deltaDBD/deltaDBD cells), early blood progenitors are formed. However, gene expression during differentiation becomes progressively deregulated and terminal differentiation is severely compromised. Here we studied the cooperation of Sp1 and its closest paralogue Sp3 in hematopoietic development and demonstrate that Sp1 and Sp3 binding sites largely overlap. Sp3 cooperates with Sp1deltaDBD/deltaDBD but is unable to support hematopoiesis in the complete absence of Sp1. Using single cell gene expression analysis, we show that the lack of Sp1 DNA binding leads to a distortion of cell fate decision timing, indicating that stable chromatin bi nding of Sp1 is required to maintain robust differentiation trajectories.
Project description:Development requires the cooperation of tissue-specific and ubiquitously expressed transcription factors, such as Sp-family members. However, the molecular details of how ubiquitous factors participate in developmental processes are still unclear. We previously showed that during the differentiation of embryonic stem cells lacking Sp1 DNA binding activity (Sp1deltaDBD/deltaDBD cells), early blood progenitors are formed. However, gene expression during differentiation becomes progressively deregulated and terminal differentiation is severely compromised. Here we studied the cooperation of Sp1 and its closest paralogue Sp3 in hematopoietic development and demonstrate that Sp1 and Sp3 binding sites largely overlap. Sp3 cooperates with Sp1deltaDBD/deltaDBD but is unable to support hematopoiesis in the complete absence of Sp1. Using single cell gene expression analysis, we show that the lack of Sp1 DNA binding leads to a distortion of cell fate decision timing, indicating that stable chromatin bi nding of Sp1 is required to maintain robust differentiation trajectories.
Project description:Development requires the cooperation of tissue-specific and ubiquitously expressed transcription factors, such as Sp-family members. However, the molecular details of how ubiquitous factors participate in developmental processes are still unclear. We previously showed that during the differentiation of embryonic stem cells lacking Sp1 DNA binding activity (Sp1deltaDBD/deltaDBD cells), early blood progenitors are formed. However, gene expression during differentiation becomes progressively deregulated and terminal differentiation is severely compromised. Here we studied the cooperation of Sp1 and its closest paralogue Sp3 in hematopoietic development and demonstrate that Sp1 and Sp3 binding sites largely overlap. Sp3 cooperates with Sp1deltaDBD/deltaDBD but is unable to support hematopoiesis in the complete absence of Sp1. Using single cell gene expression analysis, we show that the lack of Sp1 DNA binding leads to a distortion of cell fate decision timing, indicating that stable chromatin bi nding of Sp1 is required to maintain robust differentiation trajectories.
Project description:Sp1 and Sp3 belong to the Specificity proteins (Sp)/Krüppel-like transcription factor family. They are closely related, ubiquitously expressed and recognize G-rich DNA motifs. They are thought to regulate generic processes such as cell cycle and growth control, metabolic pathways and apoptosis. Ablation of Sp1 or Sp3 in mice is lethal, and combined haploinsufficiency results in hematopoietic defects during the fetal stages. Here, we show that in adult mice conditional ablation of either Sp1 or Sp3 has minimal impact on hematopoiesis, while the simultaneous loss of Sp1 and Sp3 results in severe macrothrombocytopenia and platelet dysfunction. We employed flow cytometry, cell culture and electron microscopy and show that although megakaryocyte numbers are normal in bone marrow and spleen, they display a less compact demarcation membrane system and a striking inability to form proplatelets. Through megakaryocyte transcriptomics and platelet proteomics we identified several cytoskeleton-related proteins and downstream effector kinases, including Mylk, that were downregulated upon Sp1/Sp3 depletion, providing an explanation for the observed defects in megakaryopoiesis. We show that Mylk is required for proplatelet formation and stabilization and for ITAM-receptor mediated platelet aggregation. Our data highlights the specific vs generic role of these ubiquitous transcription factors in the highly specialized megakaryocytic lineage. Megakaryocyte mRNA profiles of Sp1fl/fl::Sp3fl/fl (WTlox) and Pf4-Cre::Sp1fl/fl::Sp3fl/fl (dKO) mice were generated by deep sequencing, in triplicate.
Project description:Sp1 and Sp3 belong to the Specificity proteins (Sp)/Krüppel-like transcription factor family. They are closely related, ubiquitously expressed and recognize G-rich DNA motifs. They are thought to regulate generic processes such as cell cycle and growth control, metabolic pathways and apoptosis. Ablation of Sp1 or Sp3 in mice is lethal, and combined haploinsufficiency results in hematopoietic defects during the fetal stages. Here, we show that in adult mice conditional ablation of either Sp1 or Sp3 has minimal impact on hematopoiesis, while the simultaneous loss of Sp1 and Sp3 results in severe macrothrombocytopenia and platelet dysfunction. We employed flow cytometry, cell culture and electron microscopy and show that although megakaryocyte numbers are normal in bone marrow and spleen, they display a less compact demarcation membrane system and a striking inability to form proplatelets. Through megakaryocyte transcriptomics and platelet proteomics we identified several cytoskeleton-related proteins and downstream effector kinases, including Mylk, that were downregulated upon Sp1/Sp3 depletion, providing an explanation for the observed defects in megakaryopoiesis. We show that Mylk is required for proplatelet formation and stabilization and for ITAM-receptor mediated platelet aggregation. Our data highlights the specific vs generic role of these ubiquitous transcription factors in the highly specialized megakaryocytic lineage.