Gene Regulatory Mechanisms that Repress BMP2 in Pathological Calcification

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Abstract The goal of this project is to understand how aging and chronic kidney disease (CKD) promote bone morphogenetic protein 2 (BMP2) synthesis that furthers pathological calcification of the heart valves and vasculature. Post-transcriptional regulatory mechanisms repress BMP2 in aorta and aortic valve. We hypothesize that (1) this repression is essential for controlling BMP2 levels in the adult and that (2) conditions such as aging and CKD impair the function of factors that mediate this repression in healthy heart valves and aorta. We are testing these hypotheses in aged normal mice (24 months) and in the Klotho mutant mouse which models age-related disorders, including extensive calcification of the heart valves and vasculature. AIM 1 is to test the influence of conditionally deleting a strong repressive element in the 3’untranslated region (UTR) of Bmp2 on calcification in normal aged mice and in Klotho mice with premature aging and aging associated renal dysfunction. Recently developed Bmp2 alleles are used to assess how the deletion of this potent post-transcriptional repressor influences the course of calcification associated with aging and renal dysfunction. Preliminary results indicate that the UCS inhibits calcification. AIM 2 is to identify and compare miRNA signatures unique to young, healthy aorta and aortic valve to the signatures of these tissues from normal aged mice and in Klotho null mice with premature aging and severe vascular calcification. Within these profiles, we will focus on post- transcriptional repressive factors (miRNAs) that target the Bmp2 UCS and contribute to 3’UTR mediated repression in healthy tissues. AIM 3 is to test how selected and validated miRNAs influence the expression Bmp2 and downstream osteogenic events that lead to calcification in Klotho null mice bearing our unique transgenes. The outcomes of the proposed research will be (1) increased understanding of how BMP2 influences pathological calcification, (2) the identification and analyses of potential miRNA biomarkers, and (3) new therapeutic leads for controlling pathological calcification. The purpose of this revision is to request supplemental funds to support Ms. Lindsey Hernandez, a Hispanic woman, under the auspices of the Research Supplement to Promote Diversity in Health- Related Research (Announcement Number PA-18-906). Ms. Hernandez goal is to enter a doctoral program in genetics. The proposed research experience will directly improve the competitiveness of Ms. Hernandez applications to graduate school. As described in the Research Plan, Ms. Hernandez will be directly involved in the goals of the parent grant, with specific experiments delineated for her training.