| GFI1B belongs to the GFI1 family of transcriptional repressors essential for hematopoietic development, particularly in erythroid and megakaryocytic lineages. It contains an N-terminal SNAG domain that mediates repression through recruitment of chromatin modifiers like CoREST, LSD1, and HDAC1/2, alongside a C-terminal array of zinc fingers that bind specific DNA motifs in target gene regulatory regions. GFI1B drives transcriptional silencing by assembling these corepressor complexes at promoter and enhancer sites, thereby suppressing genes involved in progenitor proliferation and lineage commitment during hematopoiesis. In hematopoietic stem and progenitor cells, GFI1B integrates with GATA1 to autoregulate its own expression and coordinate differentiation programs, while also modulating TGF-β signaling to restrict bipotent erythroid-megakaryocytic progenitors toward mature cell fates. This repression extends to metabolic pathways, where GFI1B epigenetically controls fatty acid oxidation and oxidative phosphorylation genes, maintaining stem cell dormancy and preventing aberrant proliferation. Within megakaryocyte-erythroid progenitors, GFI1B enforces lineage fidelity by dampening self-renewal signals and promoting terminal maturation, with its absence disrupting red blood cell and platelet production. Dysregulation through mutations or low expression activates pathways like JAK-STAT, MAPK, and ROS signaling, contributing to leukemia progression by favoring blast cell survival and metabolic reprogramming. Tissue-specific expression peaks in hematopoietic compartments, where GFI1B levels decline from stem cells to differentiated progeny except in megakaryocyte precursors. |
Lane 1: HEL, Lane 2: TF-1
