Abstract 252: Is Zbp1 An Atherosclerosis Modifier Gene?

We have previously mapped and fine mapped a mouse atherosclerosis susceptibility locus on chromosome 2 using an intercross between AKR/J and DBA/2J strains on the apoE-deficient background. The fine mapped locus includes only 3 protein coding genes, and the Zbp1 gene, encoding the Z-DNA binding protein 1, is our top candidate. Prior single cell RNAseq from the mouse aorta shows Zbp1 expression in monocytes and macrophages > endothelial cells and fibroblasts. The ZBP1 protein plays a role in non-canonical necroptosis and inflammatory signaling. There are 2 mouse Zbp1 mRNA splice isoforms, long and short, which respectively generate a full length protein and a C-terminal truncated isoform that is missing the RHIM domains required for necroptosis activity. RNAseq from bone marrow derived macrophages reveals ~2-fold higher Zbp1 expression in DBA/2 vs. AKR macrophages (p=0.002), with a short to long isoform ratio of about 2.5. After treatment with LPS, Zbp1 expression is induced ~30-fold (p<0.0001), with a short to long isoform ratio of about 0.9. These results were confirmed by qPCR. To determine if Zbp1 is an atherosclerosis modifier gene, we treated wildtype (WT) and Zbp1 knockout (KO) female mice, both on the C57BL/6J background, with LDLr antisense oligos (ASO) for 8 weeks while feeding a western-type diet. Upon sacrifice at 16 weeks of age, body weights and total cholesterol levels (~800 mg/dl) were similar in the WT and KO mice. Median aortic root lesion area was decreased by 30% in the KO vs. WT mice (Figure). The median necrotic lesion area and % necrotic lesion area were decreased by 44% and 33%, respectively in the KO vs. WT mice (Figure). Although these results were not statistically significant, these trends encouraged us to look at more advanced lesions and follow up study is underway with a 16-week exposure to LDLr ASO and western-type diet. Thus, Zpb1 appears to be an atherosclerosis modifier gene that may function by increasing lesion necrosis.