1Department of Biochemistry, Faculty of Medical Sciences, Tarbiat Modares University, POB 14115-111, Tehran, Iran
2Institute of Molecular Medicine and Max-Plank Research group on stem cell aging. University of Ulm, Ulm, Germany
Background and aims: The E2F family of transcription factors is encoded by at least eight genes, E2F1-8. These proteins are important targets of the retinoblastoma protein (RB) contributed in regulation of transcription, cell cycle and apoptosis. The aim of this study was to investigate the expression levels of E2F protein family including E2F1, E2F2, E2F7, E2F8 and RB1 in the lineage negative (Lin-) hematopoietic stem cells (HSCs) of young and aged black mice using Real Time RT-PCR and western blot techniques. Methods: Lin- HSCs of 4 young (7-10 weeks old) and 3 aged (76 weeks old ) mice have been isolated from their bone marrow cells using MACS column and after RNA extraction of culturing cells and cDNA preparation, samples were then analyzed by Real Time RT- PCR and western blot techniques. Results: The E2F7 and E2F8 expression levels of the Lin- HSCs of old mice were only the transcriptional factors significantly decreased when compared with young mice. In conclusion: It seems the functional roles of important E2F7 and E2F8 transcription factors in moderating potentially destructive activity of E2F1 and regulation of cell cycle have been diminished in Lin- HSCs of aged mice. Hence, the apoptotic activity of the E2F1 would affect to the most HSCs, reinforcing bone marrow to proliferate the HSCs in old mice. However, Real Time RT-PCR data showed that the expression level of the E2F1 in those cells was not increased significantly as expected. This is the first report in this regard and further investigation with more samples need to reconfirm these data.