Developmental Regulation of Aortic Elastin Gene Expression Involves Disruption of an IGF-I Sensitive Repressor Complex

Nuclear proteins were isolated from different aged chick embryonic aorta and examined by gel mobility shift and footprint analyses using the -195 to +2 bp region of the human elastin gene. A major developmental change in DNA/protein complexes involved the loss of binding complexes present initially in the 8- to 11-day nuclear extracts. Both chemical and enzymatic footprinting demonstrated that the deprotected binding complexes corresponded to positions -167 to -137 bp within the elastin promoter fragment. Gel shift competition assays confirmed the identity of the specific DNA sequences affected. These results demonstrate that increased elastogenesis during aortic embryogenesis involves the derepression of a negative element functionality previously shown to be affected by IGF-I in vitro.