Alu Tandem Sequences Inhibit GFP Gene Expression by Triggering Chromatin Wrapping

摘要

Alu elements belonging to the short interspersed nuclear elements (SINE) of repetitive elements are present in more than one million copies which altogether represent 10% of the whole human genome. In this study, the roles of Alu tandem sequences in the process of GFP gene (GFP) expression and packing into chromatin of its DNA were studied. §b detect the effect of Alu repeats on gene expression, different copies of Alus were inserted GFP ddffristream respectively in pEGFP-Cl vector. We found that Alu sequences decreased the amount of GFP transcription, the percentage of GFP positive cells and the accessibility to DNase I in length-dependent manner. Inserting Alu caused the production of higher-molecular-mass RNA, indicating Alu sequence did not induce premature transcriptional termination. Tight packing chromatins keep silent and resist to DNase I digestion, which is a general phenomenon. We suggested that head and tail tandem Alu sequences suppressed GFP expression in length dependent manner by triggering chromatin packing.