Pluto Bioinformatics

GSE58707: Sp1/Sp3 transcription factors regulate hallmarks of megakaryocyte maturation, and platelet formation and function

Bulk RNA sequencing

Sp1 and Sp3 belong to the Specificity proteins (Sp)/Krppel-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.; SOURCE: Harmen,Jan George,van de Werken (h.vandewerken@erasmusmc.nl) - Cell Biology Erasmus MC