BACKGROUND Gfi-1 (growth factor independence-1) encodes a nuclear zinc-finger transcription factor and was first identified as an integration site of Moloney murine leukemia virus in a screen for T cell IL-2-independent growth. Subsequently, Gfi-1 was found to be a frequent target of proviral insertion in T and B cell lymphomas. Overexpression of Gfi-1 abolishes G1 cell cycle arrest and apoptosis induced by growth factor withdrawal. Transgenic mice that express high levels of Gfi-1 in T cells are predisposed to T cell lymphoma. Gfi-1 has further been shown to cooperate with c-Myc and Pim1 in lymphomagenesis.1 In addition Gfi-1 may play a role in lung and prostate cancers. Targeted disruption of Gfi-1 in mice has revealed an important role of Gfi-1 in normal hematopoiesis. Gfi-1−/− mice are defective in T and B cell development. Gfi-1−/− mice also lack mature granulocytes because of a block in granulocytic differentiation. Consistent with its role in granulopoiesis, mutations in Gfi-1, albeit rare, have been reported in a small group of patients with severe congenital neutropenia (SCN), a disease characterized by an early block in granulocytic differentiation. Gfi-1 also acts to restrict the proliferation of hematopoietic stem cell (HSC) and thereby preserve their functional integrity.2 Additionally Gfi-1 has been shown to regulate the development of nonhematopoietic cells including inner ear hair cells, lung neuroendocrine cells and intestinal epithelial cells.
Gfi-1 functions mainly as a repressor of transcription. It represses its target genes by binding to consensus DNA elements containing the AATC core sequence. The Gfi-1 protein consists of an N-terminal SNAG domain required for nuclear localization, a central region and 6 C-terminal zinc fingers (ZFs) involved in DNA binding. The SNAG domain is important for transcriptional repression; however, Gfi-1 may repress transcription through both SNAG domain-dependent and independent mechanisms. The different domains of Gfi-1 have been implicated in recruiting corepressors and histone modifying enzymes, including eight-twenty-one (ETO), CoREST, histone demethylase LSD1, histone deacetylases (HDACs) 1 and 2, and the histone lysine methyltransferase G9a. The mechanisms by which Gfi-1 controls cell proliferation and survival are still poorly understood. It has been shown that Gfi-1 binds to and represses CDKN1A encoding the cyclin-dependent kinase inhibitor (CDKI) p21Cip, and the proapoptotic Bcl2 family member Bax. Myc-interacting zinc finger protein-1 (Miz-1) is a POZ-ZF transcription factor originally identified as a binding partner of c-Myc. Miz-1 possesses a potent anti-growth activity and has been shown to activate transcription by directly binding to the initiator (Inr) elements in its target genes, including Mad4, CDKN1A, and CDKN2B encoding the CDKI p15INK4B. It was shown that Gfi-1 interacts with Miz-1 and is recruited to the core promoter of CDKN2B via Miz-1, leading to transcriptional repression.3 In addition, Gfi1 functions as an antagonist of NF-kappaB activity at the level of promoter binding. This suggested a new function of Gfi1 as a general negative regulator of the endotoxin-initiated innate immune responses, including septic shock and possibly other severe inflammatory diseases.4
1. Wallis, D. et al: Development 130, 221-32, 2003
2. Hock, H. et al: Nature 431:1002-7, 2004
3. Basu, S. et al: Proc. Natl. Acad. Sci. USA 106:1433-8, 2009
4. Sharif-Askari,E. et al: Mol. Cell. Biol. 30:3929-42, 2010
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Raised against recombinant human Gfi-1 fragments expressed in E. coli.
Species & predicted
reactivity ( ):
Weight of protein:
Detects endogenous Gfi-1 proteins without cross-reactivity with other family members.
Store at -20°C, 4°C for frequent use. Avoid repeated freeze-thaw cycles.
*Optimal working dilutions must be determined by end user.