ABSTRACT
Objective: Growth factor independence 1 (GFI1), a transcriptional repressor, is required for hematopoietic stem cell maintenance and self-renewal in addition to controlling differentiation and proliferation of myeloid cells. As murine studies have demonstrated that this transcription factor has a notable role in the initiation and progression of acute myeloid leukemia (AML) disease, the aim of the current study was to investigate and review the influence of GFI1 in human AML cells. Methods: GFI1 expression levels were measured by means of real-time polymerase chain reaction in 96 primary AML samples which were then compared to gene expression levels observed in 18 healthy subjects. Moreover, GFI1 expression patterns were analyzed based on specific AML subtypes including acute promyelocytic leukemia (APL). Finally, leukemic cells were stained to measure levels of myeloperoxidase (MPO) activity. Results: This study reports that AML patients have significantly higher GFI1 mRNA levels in comparison to healthy subjects and that, when considering AML subtypes, patients with APL have higher GFI1 expression than non-APL patients. Conclusion: It is also concluded that GFI1 overexpression in patients with high MPO levels, such as those of the APL subtype, is correlated with favorable disease prognosis as supported by other studies which demonstrate that increased peroxide activity and GFI1 are independently correlated with a favorable prognosis
ABSTRACT
Eukaryotic chromatin is organized as radial DNA loops with periodical attachments to an underlying nucleoskeleton known as nuclear matrix. This higher order chromatin organization is revealed upon high salt extraction of cells. To understand the sequential change in the functional organization of chromatin during spermatogenesis, we have analysed the higher order organization of chromatin in different testicular cell types and the epididymal sperm of laboratory mouse. The expansion and contraction of the nucleoid DNA following 2 M NaCl extraction was measured in a fluorescence microscope using ethidium bromide (2.5-200 mg/mL) as an intercalating dye to induce DNA positive supercoils. While the halo size varied among cell types (pachytene DNA most extended, round spermatid least), 5 mg/mL ethidium bromide (EtBr) removed maximum negative supercoils in all the cell types. At higher EtBr concentrations, maximum positive supercoiling occured in pachytene DNA loops. Consistent with this, the pachytene looped domains were maximally sensitive to DNase I, while the elongated spermatids and sperms were highly resistant. Our data suggest that pachytene DNA is in the most open chromatin conformation of all testicular cell types, while round spermatids show the most compact conformation in terms of EtBr intercalation.