APOLIPOPROTEIN(A) GENE ENHANCER RESIDES WITHIN A LINE ELEMENT

Apolipoprotein(a), (apo(a)), is the distinguishing protein portion of the lipoprotein(a) particle, elevated plasma levels of which are a maj or risk factor for cardiovascular disease. A search for enhancer eleme nts that control the transcription of the apo(a) gene led to the ident ification of an upstream element that contains target binding sites fo r members of the Ets and Sp1 nuclear protein families. The enhancer el ement functions in either orientation to confer a greater than 10-fold increase in the activity of the apo(a) minimal promoter in cultured h epatocyte cells. Unexpectedly, the enhancer element is located within a LINE retrotransposon element, suggesting that LINE elements may func tion as mobile regulatory elements to control the expression of nearby genes.