Study Of The Distal Regulatory Action On α-globin Gene Cluster

Distal regulation elements are widely dispersed in genome of higher eukaryotes. They occur so frequecntly and play critical roles in the process of cellular diffierentication and organic development. Many types of distal regulatory elements have been identified, including enhancers, locusl contral regions (LCRs), global control regions (GCRs) and insulators/bunderys. Amony them, distal enhancing elements, the enhancers, LCRs and GCRs, regulate their target genes by activating their transcription. They can exert their effects from several hundred bp to several hundred kb far away from the promoters of their targets.How such distal regulatory elements work is one of the basic and pivotal problems in the field of molecular biology. In the past years two types of models, contact model and non-contact model, have been pruposed to explain the action of distal enhancing elements. The contact model place emphasis on the phsical contact between distal enhancing elements and their target promoters. Looping model is a deputy of contact model. It suggests that distal enhancing elements can form holocomplex with promoters they regulated by loop out the interval DNA fragments. While non-contact model stresses that rather then phasical contact the distal enhance elements can transfer protein factors such as enhancer facilitator along DNA strand to the target promoters to regulate their expression.