| Objective: Our previous study has shown that β-arrestin1was amultifunction protein that can regulate the lifespan of theCD34+CD38-CD19+subfractions of acute B-lymphoblastic leukemiainitiation cells. However, the molecular mechanism is unclear. In this study,we used Raji cells, the acute B lymphobcytic leukemia cell line, toinvestigation the function of β-arrstin1in Raji cell and uncover itsmechanism for lifespan.Methods: Raji cells knocked down β-arrestin1(Raji-siβ1) and Rajicells transfected with non-specific-siRNA (Raji-Ctrl) were used toinvestigation the function of β-arrestin1in regulating B-ALL lifespan. Theβ-gal and double population assays were performed to investigate theeffect of β-arrestin1in cell aging. RT-PCR and Western Blot were used todetect the expression of hTERT. TRAP, Southern Blot and FISH assaywere used to detect the telomerase activation and telomere length,respectively. The dual luciferase reporter gene assay, EMSA, confocal andCo-IP assays were performed to investigate the mechanism of β-arrestin1 in regulating cells lifespan. All the statistic analysis was performed onSPSS17.0.Results: The number of senescent cells was increased and doublepopulation time was prolonged when β-arrestin1was knocked down in Rajicells. In Raji-siβ1cells, the telomerase activity was lower and telomere waslonger compared with those in Raji-Ctrl cells. The transcription and proteinexpression levels of hTERT were decresed and the interaction of majortranscription factor sp1and coactivater p300was weaker in Raji-siβ1cellsthan thaose in Raji-Ctrl cells. The enrichment of sp1was decreased in thepromoter regions of hTERT and its transcriptional activity was decreasedwhen β-arrestin1was knocked down in Raji cells.Conclusion: β-arrestin1could prolonge the lifespan of B-ALL Rajicells through enhancing the interaction of sp1and p300, further increasedthe enrichment of sp1in the promoter regions of hTERT, thus resulted inactivation of hTERT transcription. |
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