The LDL receptor-related protein (LRP1/A2MR) and coronary atherosclerosis--novel genomic variants and functional consequences.

The LDL receptor-related protein/alpha 2-macroglobulin receptor (LRP1/A2MR) is a multifunctional cell-surface glycoprotein that endocytoses several structurally and functionally distinct ligands. In clinical studies different genomic variants of the LRP1/A2MR and its role in the development of degenerative diseases like atherosclerosis or Alzheimer's disease were studied. We screened for novel genomic variants of LRP1/A2MR and investigated the importance of these variants in 214 coronary patients suffering from myocardial infarction as well as in 224 healthy controls. We detected a novel C>G polymorphism at position -25 in the functionally important promoter region of LRP1/A2MR. This polymorphism (c.1-25C>G) leads to the creation of a new GC-box, recognized by the constitutively expressed SP 1 transcription factor. Investigating the LRP1/A2MR gene expression with respect to this polymorphism, carriers of the mutant G-allele were found to have a higher mRNA expression level. A novel polymorphism in exon 22 (c.4012C>T), and two novel polymorphisms in intron 24 (IVS24+123C>A and IVS24+690G>A) associated with a previously described polymorphism in exon 61 (c.10249G>A), were related to the development of myocardial infarction. Two novel rare genetic variants of exon 88 (c.13933C>T) and intron 88 (IVS88+15G>A) were identified in four patients with severe coronary symptoms. However, the LRP1/A2MR gene expression was found to be independent of all identified novel genomic variants as well as other previously described changes (A217V, A775P, D2080N, D2632E, G4379S) except the promoter polymorphism.