GFI1B

This gene encodes a zinc-finger containing transcriptional regulator that is primarily expressed in cells of hematopoietic lineage. The encoded protein complexes with numerous other transcriptional regulatory proteins including GATA-1, runt-related transcription factor 1 and histone deacetylases to control expression of genes involved in the development and maturation of erythrocytes and megakaryocytes. Mutations in this gene are the cause of the autosomal dominant platelet disorder, platelet-type bleeding disorder-17. Alternate splicing results in multiple transcript variants. [provided by RefSeq, Aug 2014]

Growth Factor Independent 1B Transcriptional Repressor

Essential proto-oncogenic transcriptional regulator necessary for development and differentiation of erythroid and megakaryocytic lineages. Component of a RCOR-GFI-KDM1A-HDAC complex that suppresses, via histone deacetylase (HDAC) recruitment, a number of genes implicated in multilineage blood cell development and controls hematopoietic differentiation. Transcriptional repressor or activator depending on both promoter and cell type context; represses promoter activity of SOCS1 and SOCS3 and thus, may regulate cytokine signaling pathways. Cooperates with GATA1 to repress target gene transcription, such as the apoptosis regulator BCL2L1; GFI1B silencing in leukemic cell lines markedly increase apoptosis rate. Inhibits down-regulation of MYC and MYB as well as the cyclin-dependent kinase inhibitor CDKN1A/P21WAF1 in IL6-treated myelomonocytic cells. Represses expression of GATA3 in T-cell lymphomas and inhibits GATA1-mediated transcription; as GATA1 also mediates erythroid GFI1B transcription, both GATA1 and GFI1B participate in a feedback regulatory pathway controlling the expression of GFI1B gene in erythroid cells. Suppresses GATA1-mediated stimulation of GFI1B promoter through protein interaction. Binds to gamma-satellite DNA and to its own promoter, auto-repressing its own expression. Alters histone methylation by recruiting histone methyltransferase to target genes promoters. Plays a role in heterochromatin formation.

Chromatin organization Source: UniProtKB-KW
Negative regulation of G1/S transition of mitotic cell cycle Source: GO_Central
Negative regulation of transcription by RNA polymerase II Source: GO_Central
Regulation of hemopoiesis Source: GO_Central
Regulation of transcription by RNA polymerase II Source: GO_Central

Nucleus

Bleeding disorder, platelet-type, 17 (BDPLT17):
An autosomal dominant disorder characterized by increased bleeding tendency due to platelet dysfunction, and associated with macrothrombocytopenia and red cell anisopoikilocytosis. Platelets appear abnormal on light microscopy, while electron microscopy shows a heterogeneous decrease of alpha granules within platelets. Bone marrow biopsy shows increased numbers of abnormal megakaryocytes, suggesting a defect in megakaryopoiesis and platelet production. The severity of bleeding is variable with some affected individuals experiencing spontaneous bleeding while other exhibit only abnormal bleeding with surgery.

Methylation at Lys-8 in the SNAG domain seems required for the recruitment of the corepressor complex.